Journals >Spectroscopy and Spectral Analysis
Contents
2015
Volume: 35 Issue 11
59 Article(s)
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Research Article
Radiance Simulation of BUV Hyperspectral Sensor on Multi Angle Observation, and Improvement to Initial Total Ozone Estimating Model of TOMS V8 Total Ozone Algorithm
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
New hyperspectral sensor to detect total ozone is considered to be carried on geostationary orbit platform in the future, because local troposphere ozone pollution and diurnal variation of ozone receive more and more attention. Sensors carried on geostationary satellites frequently obtain images on the condition of larNew hyperspectral sensor to detect total ozone is considered to be carried on geostationary orbit platform in the future, because local troposphere ozone pollution and diurnal variation of ozone receive more and more attention. Sensors carried on geostationary satellites frequently obtain images on the condition of larger observation angles so that it has higher requirements of total ozone retrieval on these observation geometries. TOMS V8 algorithm is developing and widely used in low orbit ozone detecting sensors, but it still lack of accuracy on big observation geometry, therefore, how to improve the accuracy of total ozone retrieval is still an urgent problem that demands immediate solution. Using moderate resolution atmospheric transmission, MODTRAN, synthetic UV backscatter radiance in the spectra region from 305 to 360 nm is simulated, which refers to clear sky, multi angles (12 solar zenith angles and view zenith angles) and 26 standard profiles, moreover, the correlation and trends between atmospheric total ozone and backward scattering of the earth UV radiation are analyzed based on the result data. According to these result data, a new modified initial total ozone estimation model in TOMS V8 algorithm is considered to be constructed in order to improve the initial total ozone estimating accuracy on big observation geometries. The analysis results about total ozone and simulated UV backscatter radiance shows: Radiance in 317.5 nm (R317.5) decreased as the total ozone rise. Under the small solar zenith Angle (SZA) and the same total ozone, R317.5 decreased with the increase of view zenith Angle (VZA) but increased on the large SZA. Comparison of two fit models shows: without the condition that both SZA and VZA are large (>80°), exponential fitting model and logarithm fitting model all show high fitting precision (R2>0.90), and precision of the two decreased as the SZA and VZA rise. In most cases, the precision of logarithm fitting mode is about 0.9% higher than exponential fitting model. With the increasing of VZA or SZA, the fitting precision gradually lower, and the fall is more in the larger VZA or SZA. In addition, the precision of fitting mode exist a plateau in the small SZA range. The modified initial total ozone estimating model (ln(I) vs. Ω) is established based on logarithm fitting mode, and compared with traditional estimating model (I vs. ln(Ω)), that shows: the RMSE of ln(I) vs. Ω and I vs. ln(Ω) all have the down trend with the rise of total ozone. In the low region of total ozone (175～275 DU), the RMSE is obvious higher than high region(425～525 DU), moreover, a RMSE peak and a trough exist in 225 and 475 DU respectively. With the increase of VZA and SZA, the RMSE of two initial estimating models are overall rise, and the upraising degree is ln(I) vs. Ω obvious with the growing of SZA and VZA. The estimating result by modified model is better than traditional model on the whole total ozone range (RMSE is 0.087%~0.537% lower than traditional model), especially on lower total ozone region and large observation geometries. Traditional estimating model relies on the precision of exponential fitting model, and modified estimating model relies on the precision of logarithm fitting model. The improvement of the estimation accuracy by modified initial total ozone estimating model expand the application range of TOMS V8 algorithm. For sensor carried on geostationary orbit platform, there is no doubt that the modified estimating model can help improve the inversion accuracy on wide spatial and time range This modified model could give support and reference to TOMS algorithm update in the future..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 2979 (2015)
Detection of Atmospheric HONO and NO2 by Incoherent Broadband Cavity Enhanced Spectroscopy
WU Tao, CHEN Wei-dong, and HE Xing-dao
We report on the development of an optical instrument based on LED-IBBCEAS for simultaneous measurements of nitrous acid (HONO) and nitrogen dioxide (NO2) in ambient air. The light emitting from the LED centered at 365 nm was directly focused into the cavity formed with two high reflectivity mirrors, separated by a disWe report on the development of an optical instrument based on LED-IBBCEAS for simultaneous measurements of nitrous acid (HONO) and nitrogen dioxide (NO2) in ambient air. The light emitting from the LED centered at 365 nm was directly focused into the cavity formed with two high reflectivity mirrors, separated by a distance of 1.76 m. The light output of the cavity was received with a portable spectrometer. The mirror reflectivity was calibrated by absorption spectra of NO2 and O2-O2. In the spectral range of 353～376 nm, the maximum mirror reflectivity was found to be 0.999 17. Detection limits (1σ) of 0.6 ppbv for HONO and 1.8 ppbv for NO2 were achieved with an acquisition time of 120 s. In order to test the accuracy of measured results by present setup, concentrations of NO2 were recorded during continuous 56 hours and compared with data from a NOX analyzer equipped with a blue light converter. The least-square fit lines give gradients of 1.09 and respective intercepts of 3.45, with a linear correction factor of 0.89. The concentrations of HONO and NO2 in indoor air were monitored, the concentrations of HONO varied from near 0 to 5.3 ppbv in 24 hours, the averaged concentration was 1.8 ppbv, and the concentrations of NO2 varied from 5 to 51 ppbv at the same time, the averaged concentration was 21.9 ppbv..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 2985 (2015)
Quantitative Measurement of Equivalence Ratios of Methane/Air Mixture by Laser-Induced Breakdown Spectroscopy: the Effects of Detector Gated Mode and Laser Wavelength
ZUO Peng, LI Bo, YAN Bei-bei, LI Zhong-shan, and YAO Ming-fa
Laser-induced breakdown spectroscopy (LIBS) has been increasingly used in combustion diagnostics as a novel spectral analysis method in recent years. The quantitative local equivalence ratio of methane/air mixture is determined by LIBS using different emission intensity ratios of H/O and H/N. The comparison between calLaser-induced breakdown spectroscopy (LIBS) has been increasingly used in combustion diagnostics as a novel spectral analysis method in recent years. The quantitative local equivalence ratio of methane/air mixture is determined by LIBS using different emission intensity ratios of H/O and H/N. The comparison between calibration curves of H656/O777 and H656/N746 is performed in gated mode, which shows that H656/O777 can achieve better prediction accuracy and higher sensitivity. More spectral intensity ratios (H656/O777, H656/N+500, H656/N+567 and H656/N746) can be used to make calibration measurements in ungated mode and H656/O777 is also tested best among them. The comparison between gated and ungated detection modes shows that gated mode offers better accuracy and precision. In addition, the effects of different laser wavelengths (1 064, 532 and 355 nm) on LIBS spectra and calibration curves are investigated with laser focal point size and laser fluence kept constant. The results show that with longer laser wavelength, the peak intensity and SNR of H, O and N lines increase, as well as the slope of calibration curve of H656/O777. Among these three wavelengths, 1 064 nm laser is best suited to measure the equivalence ratio of CH4/air mixture by LIBS. The experimental results are explained in terms of plasma electron density and temperature, which have a significant impact on the emission intensity and the partition function of hydrogen and oxygen, respectively..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 2990 (2015)
Laser Raman Spectroscopy and Its Application in Gas Hydrate Studies
FU Juan, WU Neng-you, LU Hai-long, WU Dai-dai, and SU Qiu-cheng
Gas hydrates are important potential energy resources. Microstructural characterization of gas hydrate can provide information to study the mechanism of gas hydrate formation and to support the exploitation and application of gas hydrate technology. This article systemly introduces the basic principle of laser Raman spGas hydrates are important potential energy resources. Microstructural characterization of gas hydrate can provide information to study the mechanism of gas hydrate formation and to support the exploitation and application of gas hydrate technology. This article systemly introduces the basic principle of laser Raman spectroscopy and summarizes its application in gas hydrate studies. Based on Raman results, not only can the information about gas composition and structural type be deduced, but also the occupancies of large and small cages and even hydration number can be calculated from the relative intensities of Raman peaks. By using the in-situ analytical technology, laser Raman specstropy can be applied to characterize the formation and decomposition processes of gas hydrate at microscale, for example the enclathration and leaving of gas molecules into/from its cages, to monitor the changes in gas concentration and gas solubility during hydrate formation and decomposition, and to identify phase changes in the study system. Laser Raman in-situ analytical technology has also been used in determination of hydrate structure and understanding its changing process under the conditions of ultra high pressure. Deep-sea in-situ Raman spectrometer can be employed for the in-situ analysis of the structures of natural gas hydrate and their formation environment. Raman imaging technology can be applied to specify the characteristics of crystallization and gas distribution over hydrate surface. With the development of laser Raman technology and its combination with other instruments, it will become more powerful and play a more significant role in the microscopic study of gas hydrate..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 2996 (2015)
Research on Real-Time Trace Gas Detection System Based on QEPAS
MA Yu-fei, YU Guang, ZHANG Jing-bo, LUO Hao, YU Xin, YANG Chao-bo, YANG Zhen, SUN Rui, and CHEN De-ying
Quartz-enhanced photoacoustic spectroscopy (QEPAS) technology was invented lately. Therefore it’s an innovative method for trace gas detection compared with other existed technologies. In this paper, we studied the trace gas detection system based on QEPAS, and the atmospheric H2O was selected as the target analyte. InQuartz-enhanced photoacoustic spectroscopy (QEPAS) technology was invented lately. Therefore it’s an innovative method for trace gas detection compared with other existed technologies. In this paper, we studied the trace gas detection system based on QEPAS, and the atmospheric H2O was selected as the target analyte. In theory, the principles of laser wavelength modulation and signal harmonic detection were analyzed firstly, and the realizing solutions for the gas concentration retrieving and laser wavelength locking were obtained. Furthermore, the selection principle of absorption line for high sensitivity gas detection was discussed. In experiments, a continuous-wave distributed feedback(DFB) single mode diode laser emitting at 1.39 μm was used as the exciting source for the H2O vapor measurement. Using wavelength modulation spectroscopy and 2nd harmonic detection, the influence of laser wavelength modulation depth on QEPAS signal level was investigated, and the acoustic wave enhancement of the addition of micro-resonator in the acoustic detection module was analyzed as well. After optimization of the QEPAS system, a detection limit of 5.9 ppm for H2O vapor was obtained. We measured the H2O vapor with different concentrations, and the R-Square of 0.98 was achieved after the experimental data was linear fitted, indicated that the QEPAS system had an excellent linear response ability. Finally, continuous monitoring of atmospheric H2O concentration levels for a period of 12 hours was performed when the line locking mode was employed with the help of 3rd harmonic detection. The experimental results showed that this QEPAS scheme had a stable performance and outstanding continuous measuring capacity, and it can be widely used in high sensitivity on-line measurement for other trace gases detection fields..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3003 (2015)
Optical Spectroscopy for High-Pressure Microwave Plasma Chemical Vapor Deposition of Diamond Films
CAO Wei, and MA Zhi-bin
Polycrystalline diamond growth by microwave plasma chemical vapor deposition (MPCVD) at high-pressure (34.5 kPa) was investigated. The CH4/H2/O2 plasma was detected online by optical emission spectroscopy (OES), and the spatial distribution of radicals in the CH4/H2/O2 plasma was studied. Raman spectroscopy was employePolycrystalline diamond growth by microwave plasma chemical vapor deposition (MPCVD) at high-pressure (34.5 kPa) was investigated. The CH4/H2/O2 plasma was detected online by optical emission spectroscopy (OES), and the spatial distribution of radicals in the CH4/H2/O2 plasma was studied. Raman spectroscopy was employed to analyze the properties of the diamond films deposited in different oxygen volume fraction. The uniformity of diamond films quality was researched. The results indicate that the spectrum intensities of C2, CH and Hα decrease with the oxygen volume fraction increasing. While the intensity ratios of C2, CH to Hα also reduced as a function of increasing oxygen volume fraction. It is shown that the decrease of the absolute concentration of carbon radicals is attributed to the rise volume fraction of oxygen, while the relative concentration of carbon radicals to hydrogen atom is also reducing, which depressing the growth rate but improving the quality of diamond film. Furthermore, the OH radicals, role of etching, its intensities increase with the increase of oxygen volume fraction. Indicated that the improvement of OH concentration is also beneficial to reduce the content of amorphous carbon in diamond films. The spectrum space diagnosis results show that under high deposition pressure the distribution of the radicals in the CH4/H2/O2 plasma is inhomogeneous, especially, that of radical C2 gathered in the central region. And causing a rapid increase of non-diamond components in the central area, eventually enable the uneven distribution of diamond films quality..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3007 (2015)
The Effect of Hydrogen Bonding on the Spectrum of HPAM in Various Systems
ZHAI Zheng
IR and UV-Vis was employed to analyzed the spectrum effect of hydrogen bonding on the partially hydrolyzed polyacrylamide polymer(HPAM). The study reveals that, the characteristic absorption peak of free amino group moves to the low frequency due to the formation of intramolecular hydrogen bonding between amide group aIR and UV-Vis was employed to analyzed the spectrum effect of hydrogen bonding on the partially hydrolyzed polyacrylamide polymer(HPAM). The study reveals that, the characteristic absorption peak of free amino group moves to the low frequency due to the formation of intramolecular hydrogen bonding between amide group and carboxyl group. In the water solution, intramolecular hydrogen bonding is the main factor that shifted maximal absorption towards long wavelength. Intramolecular hydrogen bonding and intermolecular hydrogen bonds exist at the same time in the water solution contains intermediate sodium and calcium ions. While in the high concentration solution, the main form between amide group and carboxyl group is intermolecular hydrogen bonding. The effect of hydrogen bonding on the spectrum of HPAM demonstrates different extent in various systems. In the water solution, the maximum absorption wavelength red shifts 8 nm. In the system contains sodium ions, this shift is 4 nm. And this shift is only 2 nm in the solution contains both sodium ions and calcium ions..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3012 (2015)
Comparative Study on the Molecular Structures and Spectral Properties of Ponceau 4R and Amaranth
ZHANG Yong, CHEN Guo-qing, ZHU Chun, and HU Yang-jun
The Edinburgh FLS920P steady-instantaneous fluorescence spectrometer was applied on the detection of the absorption and the emission spectra of ponceau 4R and amaranth, which are isomers to each other. After that, the spectral parameters of them were compared. Then, the density functional theory (DFT) and time-dependenThe Edinburgh FLS920P steady-instantaneous fluorescence spectrometer was applied on the detection of the absorption and the emission spectra of ponceau 4R and amaranth, which are isomers to each other. After that, the spectral parameters of them were compared. Then, the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used on the optimization of ponceau 4R and amaranth under the ground and excited state, respectively, in order to compare the differences in configurations of them under different states. On the base of the results above, the absorption and emission spectra of the two isomers were calculated with TD-DFT, and the polarized continuum model (PCM) was applied on the base of 6-311++G (d, p). The fluorescence mechanism, the relationships between the properties of fluorescence spectra and the molecular geometry were all analyzed. The results shows that, the structures of the two molecules are non-planar, these two naphthalene rings are not co-planar, respectively, and there’s hydrogen bond in amaranth. When the two isomers were on the ground state, the planarity of the naphthalene ring which exists the hydrogen bond mentioned above in amaranth is better than the corresponding part of ponceau 4R. The two isomers are nearly co-planar when they’re on the excited state. The molecular structures of ponceau 4R and amaranth optimized above are basically reasonable, for the quantum chemistry calculation spectral results are agree with the experiments. The planarity of the naphthalene rings on the right side in ponceau 4R is worse than that in amaranth, the ponceau 4R molecule experienced more vibration and rotation from the excited to the ground state, lost more energy, which lead to the reduction of energy for emitting fluorescent photons. So ponceau 4R has longer fluorescence emission wavelength than amaranth. In this paper, the molecular structure information of ponceau 4R and amaranth were obtained, and the differences of the spectral characteristics between them were found out. The results can provide references for the study of the relationship between the spectral properties and the configuration of isomers..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3017 (2015)
Endpoint Temperature Prediction of the Basic Oxygen Furnace Based on the Flame Temperature Measurement at the Converter Mouth
SHAO Yan-ming, CHEN Yan-ru, ZHAO Qi, ZHOU Mu-chun, and DOU Xiao-yu
In the basic oxygen steelmaking process, the endpoint temperature of the molten steel is one of the key factors whether the molten steel is qualified for tapping. Currently, it mainly relies on the experienced operators to control the endpoint temperature of the molten steel, and the prediction precision may vary amongIn the basic oxygen steelmaking process, the endpoint temperature of the molten steel is one of the key factors whether the molten steel is qualified for tapping. Currently, it mainly relies on the experienced operators to control the endpoint temperature of the molten steel, and the prediction precision may vary among different operators. In order to realize the effectively endpoint steel temperature prediction of the basic oxygen furnace as well as to meet the requirement of different sizes of the converter mouth, a new method based on the flame temperature measurement at the converter mouth was proposed in this paper. Firstly, a fiber-optic spectrometer system in the visible and near infrared spectral range was designed which can real-timely and effectively realize the collection of the flame radiation information at the converter mouth. Secondly, in consideration of the actual temperature of the flame and the distance between the converter and the designed system, an improved calibration method instead of the halogen lamp was adopted, and the two-color method was employed for the flame temperature measurement. Then a regression model based on the support vector machine was built with the flame temperature and several other parameters of the steel-making process as the input variables of the model. Verification experiment was carried out on 68 industrial data collected in the steelmaking workshop. The results show that the prediction accuracy of this method is superior to the experienced operators, and close to the sub-lance based method. As a result, the proposed method can provide a feasible and effective solution to the endpoint steel temperature prediction for those small-sized and medium-sized converters..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3023 (2015)
Preparation and Luminescent Properties of Blue Emitting Phosphor of Sr3(PO4)2∶Eu2+ for White LED
WEI Jian, SHEN Chang-yu, SUN Yu-huan, ZHANG Hong, WANG Le, and LI Chen-xia
A series of Sr3(PO4)2∶Eu2+ blue phosphors were synthesized by high temperature solid state method under N2-H2 reducing atmosphere. The crystal structures, excitation and emission spectra were characterized by X-ray diffraction (XRD) and Photoluminescence (PL), respectively. The results show that the Sr3(PO4)2∶Eu2+ phosA series of Sr3(PO4)2∶Eu2+ blue phosphors were synthesized by high temperature solid state method under N2-H2 reducing atmosphere. The crystal structures, excitation and emission spectra were characterized by X-ray diffraction (XRD) and Photoluminescence (PL), respectively. The results show that the Sr3(PO4)2∶Eu2+ phosphor can be efficiently excited by the wavelengths ranging from 310 to 390 nm, and the excitation peak wavelength locates at 359 nm. A wide emission spectrum (～150 nm, originating from the 4f65d1→4f7 of the Eu2+) with a peaking wavelength of 438 nm was obtained. Through the Gaussian fitting, we found that the emission band formed by two luminescence centers（430 and 459 nm）, which indicated that the Eu2+ occupied two different Sr2+ sites in the substrate of Sr3(PO4)2. As the Eu2+ doping concentration is 7%, the maximum luminous intensity was obtained. With the increasing of the doping concentration of the Eu2+, the concentration quenching effect occurred, and the emission peak wavelength has a red shift. The PL intensity of the Sr3(PO4)2∶Eu2+ phosphor is about 1.3 times than that of the blue emitting phosphor BaMgAl10O17∶Eu2+(BAM) which means that it is a promising candidate for the blue phosphor material for white LED..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3028 (2015)
Spectroscopic Properties of CeO2∶Eu3+ for White LEDs
FU Yue, CONG Yan, YANG Yang, XIAO Yu, HE Yang-yang, WANG Li-mei, and DONG Bin
Under different Eu3+ concentration, Eu3+ doped CeO2 was prepared by co-precipitation method, and the structure and luminescent properties were studied through XRD, excitation and emission spectra. The PLE spectrum shows a broad charge-transfer band from 300～400 nm, and a week excitation line at 467 arise from 7F0—5D2 tUnder different Eu3+ concentration, Eu3+ doped CeO2 was prepared by co-precipitation method, and the structure and luminescent properties were studied through XRD, excitation and emission spectra. The PLE spectrum shows a broad charge-transfer band from 300～400 nm, and a week excitation line at 467 arise from 7F0—5D2 transition in Eu3+. The red emission arise from 5D0—7F1 (592 nm)and 5D0—7F2 transitions of Eu3+ has a great increase by high concentration doping under 467 nm excitation. The wavelength at 467 nm is nicely fitting in with the widely applied emission wavelengths of blue LED chips. It is indicated that the CeO2∶Eu3+ phosphor emits efficiently red emission under the blue light which makes it possible to create white light from a combination of a blue LED chip..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3032 (2015)
Preparation and Photoluminescent Properties of Ce3+-Activated LaPO4 Nanocrystals and Core/Shell Structure
LI Zhen-ya, HUANG Shi-ming, GU Mu, and LIU Xiao-lin
Hydrophobic, monodisperse LaPO4∶Ce3+ nanoparticles, LaPO4∶Ce3+/LaPO4 and LaPO4∶Ce3+/LaPO4∶Ce3+/LaPO4 core/shell structure nanocrystals were synthesized via a high-temperature organic solution approach. The as-synthesized samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), FourHydrophobic, monodisperse LaPO4∶Ce3+ nanoparticles, LaPO4∶Ce3+/LaPO4 and LaPO4∶Ce3+/LaPO4∶Ce3+/LaPO4 core/shell structure nanocrystals were synthesized via a high-temperature organic solution approach. The as-synthesized samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and photoluminescence spectroscopy (PL). The results show that: all the samples are a monoclinic phase, Because of the size small nanoparticles, the diffraction peaks of the sample occurs width phenomenon. The LaPO4∶Ce3+ nanocrystals exhibits the characteristic emission of Ce3+ ions, the photoluminescence intensity increases first and then decreases with the increasing doping concentration of Ce3+ ions , and the best doping amount is 6 at%, with the increasing doping amount, the photoluminescence intensity decreases which may caused by the concentration quenching. Compared to LaPO4∶Ce3+ nanoparticles, the photoluminescence intensity of LaPO4∶Ce3+/LaPO4 and LaPO4∶Ce3+/LaPO4∶Ce3+/LaPO4 core/shell structure nanocrystals improves about 41% and 95% respectively, this may be a synergy of larger particle size of nanocrystals and surface passivation effect. FTIR spectra data shows that the absorption peak at 1 545 and 1 461 cm-1 corresponded to the asymmetric and symmetric stretching vibration of —COO－, the separation, Δ, between the two peaks is 84 cm-1, The mechanism of the sample surface modification by the organics might be that the oxygen atoms of the carboxyl are coordinated with the lanthunum ions by a bidentate mode..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3036 (2015)
Identification of Six Isomers of Dimethylbenzoic Acid by Using Terahertz Time-Domain Spectroscopy Technique
LIU Jian-wei, SHEN Jing-ling, and ZHANG Bo
In this paper, the absorption spectra of 6 isomers of dimethylbenzoic acid, which were widely used in chemical and pharmaceutical production as intermediate substance, were measured by using the terahertz time-domain spectroscopy (THz-TDS) system in the range 0.2～2.2 THz at room temperature. The experimental results shIn this paper, the absorption spectra of 6 isomers of dimethylbenzoic acid, which were widely used in chemical and pharmaceutical production as intermediate substance, were measured by using the terahertz time-domain spectroscopy (THz-TDS) system in the range 0.2～2.2 THz at room temperature. The experimental results show that the six measured isomers present apparent different spectral response. However, the results of using infrared spectroscopy indicates that different isomers show high similarity in absorption spectra in the range 1 450～1 700 cm-1. The vibrational frequencies are calculated by using the density functional theory (DFT), and identification of vibrational modes are given. It is clear that the absorption peaks of the 6 isomers in the range 1 450～1 700 cm-1 come from the stretching vibration of benzene ring and CO, while the absorption peaks in the terahertz range are caused by the relative wagging of benzene ring and all the chains out of plane, which lead to the different absorption characteristics of the 6 isomers in the range 0.2～2.2 THz. The results suggest that the difference and similarity of the absorption spectra observed in the two different frequency range are resulted from the difference and similarity of the molecular structures of the six isomers. By using the different absorption characteristics, we can identify the six isomers of dimethylbenzoic acid effectively. Our study indicates that it is feasible to distinguish the isomers by using terahertz and infrared spectroscopy technique. It provides an effective way to identify different isomers and test the purity of the intermediate substance in the process of production quickly and accurately..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3041 (2015)
Reseach on THz Time Domain Spectrum of Photo-Induced Insulator-Metal Phase Transition of VO2 Films
WANG Chang-lei, WU Shuai, LI Yan-feng, LIU Bo-wen, HU Ming-lie, CHAI Lu, XING Qi-rong, and WANG Qing-yue
Vanadium dioxide(VO2) film will be phase-transitioned from insulator into metal, accompanied with dramatic change on conductivity, which is named as photo-induced insulator-metal phase transition. Such phase transition of VO2 film has important application potentials in modulators or other functional devices for teraheVanadium dioxide(VO2) film will be phase-transitioned from insulator into metal, accompanied with dramatic change on conductivity, which is named as photo-induced insulator-metal phase transition. Such phase transition of VO2 film has important application potentials in modulators or other functional devices for terahertz waves. In this paper, the transmission spectrum variations before and after the photo-induced insulator-metal phase transition of vanadium dioxide film are investigated, and the phase transition properties in terahertz(THz) region are analyzed. In the experiment, the phase transition of the VO2 film was induced by a continuous wave(CW) laser source and a femtosecond(fs) laser source, respectively. Obvious changes on the THz waveforms were observed for the both mentioned means of excitation, and the amplitude attenuation, as well as the signal distortion, was intensified with the increase of the impinging optical power. The fast Fourier transform(FFT) spectra of the transmitted THz time-domain signals were analyzed and it was found that the amplitude of the transmitted spectrum decreased synchronously with the increase of the optical power, accompanied with deformation of the spectrum line shape at the same time. The reason was that the macroscopic dielectric properties of the VO2 film approached gradually to that of a metal as laser power was increased. A parameter, transmission modulation function, was defined in the paper as the amplitude difference between the transmission spectra of the VO2 film before and after the laser excitation, to describe the dispersivity of the photo-induced phase transition more clearly. From the curve of the transmission modulation function, strong frequency-dependent properties at THz frequencies were found to vary regularly with the incident light power. After furthermore comparison, it was found that, though the insulator-metal phase transition could be trigged by both CW laser source and fs laser source, the corresponding impinging optical power values were obviously alternative for the equivalent transmission modulation function. At the end of the paper, the difference of the phase transition efficiency between the two excitation methods was analyzed and discussed..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3046 (2015)
A Double Split Ring Terahertz Filter on Ploymide Substrate
HE Jun, ZHANG Tie-jun, XIONG Wei, ZHANG Bo, HE Ting, and SHEN Jing-ling
Metamaterials are artificial composites that acquire their electromagnetic properties from embeded subwavelength metalic structure. With proper design of metamaterials, numerrous intriguing phenomena that not exhibited naturally can be realized, such as invisible cloaking, perfect absorption, negative refractive index Metamaterials are artificial composites that acquire their electromagnetic properties from embeded subwavelength metalic structure. With proper design of metamaterials, numerrous intriguing phenomena that not exhibited naturally can be realized, such as invisible cloaking, perfect absorption, negative refractive index and so on. In recent years, With the development of THz technology, the extensive research onTHz metamaterials devices areattracting more and more attentions. Since silicon(Si) has a higher transmittance for THz wave, it is usually selected as substrate in metamaterials structure. However, Si has the shortcomings of hardness, not easy to bend, and fragile, which limit the application of THz metamaterials.In this work, we use polyimide as the substrate to overcome the shortcomings of the Si substrate. Polyimide isflexible, smooth, suitable for conventional lithography process and the THz transmittance can compete with that of the Si. Frist, we test the THz optical properties of polymide, and get the refractive index of 1.9, and the transmittance of 80%. Second, we design a double splits ring resonators (DSRRs), and study the properties of transmission by changing the THz incidence angle and curvature of the sample. We find the resonant amplitude and resonant frequencies are unchanged.Fabricating metamaterials structures on a thin plastic substrate is a possible way to extend plane surface filtering to curved surface filtering. Third, we try to make a broadband filter by stacking two samples, and the 181GHz bandwidth at 50% has been achieved. By stacking several plane plastic metamaterial layers with different resonance responses into a multi-layer structure, a broadband THz filter can be built. The broadband filter has the advantages of simple manufacture, obvious filtering effect, which provides a new idea for the production of terahertz band filter..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3050 (2015)
The Study on the Far-FTIR and THz Spectra of Azitromycin Drugs with Different Physical Forms
YANG Yu-ping, FAN Li-jie, CUI Bin, CHEN Gen-xiang, ZHANG Zhen-wei, and ZHANG Cun-lin
Far Fourier transform infrared spectroscopy (Far-FTIR) and terahertz time-domain spectroscopy (THz-TDS) were used to measure the fingerprint spectra of Azitromycin suspension, capsule, tablet and dispersible tablet under vacuum and nitrogen conditions, respectively. In the frequency range of 0.2～15 THz, highly resolvedFar Fourier transform infrared spectroscopy (Far-FTIR) and terahertz time-domain spectroscopy (THz-TDS) were used to measure the fingerprint spectra of Azitromycin suspension, capsule, tablet and dispersible tablet under vacuum and nitrogen conditions, respectively. In the frequency range of 0.2～15 THz, highly resolved spectral features for Azitromycin suspension were measured and some minor differences were observed between domestic and exotic Azitromycin Suspension, such as linewidth broadening and additional peaks. As same time, for the domestic Azitromycin capsule, tablet and dispersible tablet, the absorption baselines in the range of 0.2～2.7 THz rise with the increase of frequency while absorption peaks become weaker due to the scattering of bigger particles and smaller amount of Azitromycin. Also, the additional peaks are caused by the absorption of filling materials. In parallel with the qualitative measurement, the THz absorption spectra for mixtures of polyethylene (PE) powders and exotic Azithomycin suspension with different concentrations were also measured. According to the linear correlation between the concentration and the absorption intensity, the concentration of effective component can be evaluated accurately. This means that THz-TDS method is suitable for the quality inspection and evaluation of the mixed Azithromycin system..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3054 (2015)
Infrared Spectrum Analysis of Propolis and Tree Gum Collected from Different Areas
LUO Huo-lin, LIU Xing-xing, GONG Shang-ji, GUO Xia-li, and LUO Li-ping
Propolis possesses functions of antibacterial, antiviral, anticancer, and liver protection, and is known as the “purple gold”, however, the phenomenon which making and selling of counterfeit are growing in intensity. In order to establish a authenticity and quality of propolis evaluation model, in this paper, forty-onePropolis possesses functions of antibacterial, antiviral, anticancer, and liver protection, and is known as the “purple gold”, however, the phenomenon which making and selling of counterfeit are growing in intensity. In order to establish a authenticity and quality of propolis evaluation model, in this paper, forty-one Chinese propolis, one proplis from United States and two tree gums were used for experimental materials. The infrared spectrum collection was performed by Fourier transform infrared spectrometer, and principal component analysis (PCA) was used for data analysis. The result showed that, the infrared spectrum of propolis and tree gum were significantly different. The propolis characteristic peak only appeared in 2 500～3 500 and 400～1 800 cm-1. All propolis had two frequency region of characteristic peaks, 2 849.08～2 848.53 and 2 917.74～2 916.76 cm-1, but tree gum did not have characteristic peak in this region. The characteristic peaks of gum were in 1 150～1 300 and 1 550～1 650 cm-1. Differences in these aspects can be used to distinguish propolis and gum, and can be used to identify true and false propolis. We use Qinghai propolis as a standard sample, in 42 samples, the matching degree of other propolis is >80%. In addition, the result of PCA shows that tree gum and the propolis from different climate zone, or with different colors could be distinguished well. This paper firstly performed analysis on different propolis and gum by infrared spectrum, and a new method, for authenticity and quality of propolis identification, could be developed..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3058 (2015)
A Study of FTIR Spectrometry Based on a Long Optical Path on the Emission Rules of Nitrous Oxide from Soil
XIAO Guang-dong, ZHENG Ling, DONG Da-ming, ZHANG Dong-yan, ZHANG Bao-hua, and LIAO Tong-qing
The excessive emission of N2O (Nitrous oxide) will destroy the ozone layer, reasonable fertilization and adopting measures of emission reduction of N2O are of great significance to slowing down the greenhouse effect. The article studied the impact of fertilization and water on the emission of N2O from the cabbage farmlThe excessive emission of N2O (Nitrous oxide) will destroy the ozone layer, reasonable fertilization and adopting measures of emission reduction of N2O are of great significance to slowing down the greenhouse effect. The article studied the impact of fertilization and water on the emission of N2O from the cabbage farmland using FTIR spectrometry. To enhance the sensitivity of the measuring system, we used multi-reflecting mirrors to increase the optical pathlength. By comparing the infrared spectra between the before and after fertilizer application and the NIST spectral library, finally, the band at 2 160～2 225 cm-1 was chosen as the spectral characteristics band of quantitative calculation of N2O through analyzing. The research found that fertilization and water could promote the emission of N2O from the cabbage farmland soil, which could supply theory bases for emission reduction of N2O and slowing down the greenhouse effect. Finally, we also studied the diurnal emission rules of N2O from the fertilized soil; the results showed that the emission of N2O was lower at night and the results were compared with that of previous’ studies, which verifies the feasibility of this method. The results proved that FTIR with long optical path was a rapid and effective method to measure the emission rules of N2O from the cabbage farmland soil, which can measure the gas emissions of N2O from the fertilized cabbage farmland soil and compared with other traditional measuring methods, it had the advantages such as rapidness and convenience..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3063 (2015)
A Novel Method of Infrared Radiative Parameters Calculation in High Temperature Flow Field
CHEN Xiao-tian, ZHOU Jin-wei, and LI Ji-cheng
Infrared radiative parameters under high temperature was calculated using RJMCMC method under Bayesian framework presumed Smeared Rotational Band model (SRB), in order to solve the problem of radiation calculation for high speed vehicle infrared signature research. The process of calculation does not need any database Infrared radiative parameters under high temperature was calculated using RJMCMC method under Bayesian framework presumed Smeared Rotational Band model (SRB), in order to solve the problem of radiation calculation for high speed vehicle infrared signature research. The process of calculation does not need any database of parameter or priors about transition. The experiment from simulation and measured data demonstrates that the position of vibrational transition have been estimated precisely. Simultaneously, the change law of parameter estimation was consistent with theoretic SRB model, from which the integration of radiative parameters under different temperature approximated the line by line calculation (LBL) result very well..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3068 (2015)
Differentiation and Identification of Alicyclobacillus Strains by Fourier Transform Near-Infrared Spectroscopy
WANG Ruo-nan, YUE Tian-li*, YUAN Ya-hong, WANG Hu-xuan, SONG Ya-di, and WANG Jun
Fourier transform near-infrared spectroscopy(FT-NIR) can reflect the overall molecular composition of microbial cells to identify different types of microorganisms. To establish an accurate, effective method about the differentiation and identification of Alicyclobacillus strains between different species, the present Fourier transform near-infrared spectroscopy(FT-NIR) can reflect the overall molecular composition of microbial cells to identify different types of microorganisms. To establish an accurate, effective method about the differentiation and identification of Alicyclobacillus strains between different species, the present research performed the following studies by FT-NIR:（1）The FT-NIR spectra about seven type stains was clustered for data analysis. After preprocessing, reduction of data was performed by Principal Component Analysis (PCA) and Linear Discriminant Analysis(LDA), exploring the feasibility of differentiation and identification between different species, the result suggested that the PCA model can cluster the seven species of Alicyclobacillus strains correctly and the LDA model Ⅰcan predict the unknown species with 100% accuracy. It evidenced that the method could identify different species of Alicyclobacillus strains preliminary. （2）In order to improve the robustness and practicability of the model, a total of 41 Alicyclobacillus strains including type and isolated strains were prepared for LDA modelⅡ, using the same methods as mentioned before. The result indicated that the LDA model validated by fifteen sample with 86.67% accuracy. It was more perfect and more comprehensive.As a result, the FT-NIR technology combined with chemometrics method can accurately and effectively identify Alicyclobacillus strains between different microbial species..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3073 (2015)
Evaluation of Sugar Content of Huanghua Pear on Trees by Visible/Near Infrared Spectroscopy
LIU Hui-jun, and YING Yi-bin
A method of ambient light correction was proposed to evaluate the sugar content of Huanghua pears on tree by visible /near infrared diffuse reflectance spectroscopy (Vis/NIRS). Due to strong interference of ambient light, it was difficult to collect the efficient spectral of pears on tree. In the field, covering the frA method of ambient light correction was proposed to evaluate the sugar content of Huanghua pears on tree by visible /near infrared diffuse reflectance spectroscopy (Vis/NIRS). Due to strong interference of ambient light, it was difficult to collect the efficient spectral of pears on tree. In the field, covering the fruits with a bag blocking ambient light can get better results, but the efficiency is fairly low, the instrument corrections of dark and reference spectra may help to reduce the error of the model, however, the interference of the ambient light cannot be eliminated effectively. In order to reduce the effect of ambient light, a shutter was attached to the front of probe. When opening shutter, the spot spectrum were obtained, on which instrument light and ambient light acted at the same time. While closing shutter, background spectra were obtained, on which only ambient light acted, then the ambient light spectra was subtracted from spot spectra. Prediction models were built using data on tree (before and after ambient light correction) and after harvesting by partial least square (PLS). The results of the correlation coefficient(R) are 0.1, 0.69, 0.924; the root mean square error of prediction(SEP) are 0.89°Brix, 0.42°Brix, 0.27°Brix; ratio of standard deviation(SD) to SEP(RPD) are 0.79, 1.69, 2.58, respectively. The results indicate that, method of background correction used in the experimentcan reduce the effect of ambient lighting on spectral acquisition of Huanghua pears in field, efficiently. This method can be used to collect the visible/near infrared spectrum of fruits in field, and may give full play to visible/near-infrared spectroscopy in preharvest management and maturity testing of fruits in the field..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3078 (2015)
Study of Surface Enhanced Raman Spectroscopy on Copper Films Modified by Ion Beam
DING Liang-liang, HONG Rui-jin, TAO Chun-xian, and ZHANG Da-wei
Surface-enhanced Raman Spectroscopy (SERS) was a rapid non-destructive testing.It was based on detecting molecule vibrational spectrum which was adsorbed on the metallic surface. Now it was widely used in surface adsorption, electrochemical catalysis, sensors, bio-medical testing, trace amount analysis and other fieldsSurface-enhanced Raman Spectroscopy (SERS) was a rapid non-destructive testing.It was based on detecting molecule vibrational spectrum which was adsorbed on the metallic surface. Now it was widely used in surface adsorption, electrochemical catalysis, sensors, bio-medical testing, trace amount analysis and other fields. In our experiment, copper metallic films were deposited 50nm on BK7 glass substrates by direct current magnetron sputtering. And then the films were employed for the Ar ion beam etching modification.The structure, morphology and optical properties was characterized by X-ray diffraction (XRD), Atomic Force Microscope (AFM), spectrophotometer and Raman spectroscopy.In the XRD graph, the peak value of modify copper film were the same with the untreated film. So the structure of copper film was not change.With increasing the power of Ar ion, the surface roughness was changed, and scattered spectrum intensity was increased by surface roughness added. With Rhodamine B(Rh B) as a probe molecule, Raman scattered spectrum was detected on modify copper film.Compared with the different samples, we can find the Raman signal was enhanced by surface roughness added. It will have some value on study the principles of SERS..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3082 (2015)
Raman Enhancement of a Dipolar Molecule on CVD Graphene
LENG Yan-dan, ZHOU Jun-qi, ZHANG Hong-chao, and HUANG Chang-shui
The CVD graphene was chosen as the Raman enhancement substrate, graphene-enhanced Raman scattering(GERS) of dipolar molecule DREP were explored with a laser wavelength λ=532 nm of micro-Raman spectroscopy. Upon comparison of the raman signal of DREP molecular latched to a graphene /SiO2 substrate and to a bare SiO2 subThe CVD graphene was chosen as the Raman enhancement substrate, graphene-enhanced Raman scattering(GERS) of dipolar molecule DREP were explored with a laser wavelength λ=532 nm of micro-Raman spectroscopy. Upon comparison of the raman signal of DREP molecular latched to a graphene /SiO2 substrate and to a bare SiO2 substrate, we found that the Raman signal of pure DREP molecule basically does not exist at low concentrations, until it reaches a certain concentration of 1×10－5mol·L-1, its Raman signal emerging and as the increasing of the concentration, Raman signal and fluorescence signal all increase. However, the raman signal of DREP molecular on the grapheme occur at the concentration of 1×10－7mol·L-1 and as the increasing of concentration, the raman signal increasing quickly but the fluorescence signal is not obvious. The studies were shown that graphene can achieve the Raman signal of DREP molecule enhancement, and can quench fluorescent backing off, increase the ratio of Raman signal and fluorescence signals. Comparing the GERS of DREP and DR1P molecules with different molecular dipole moment, indicating that the greater the dipole moment, the greater the enhancement factor, the degree of enhancement is stronger. Finally, we analyze the mechanism of Raman enhancement about DREP molecule on the grapheme. The dipole molecular is a pyrene terminal tethered a azobenzene molecular that was modified. There will happen the electron transfer of the pyrene terminal on the graphene interface through π—π interactions, changing the energy level of grapheme and leading to a p-doping. The mechanism of Raman enhancement are chemical mechanisms. The study of GERS of DREP molecular can help the comprehension of grapheme and the mechanism of grapheme enhanced raman scattering, for example the transfer of grapheme electron, the theory of chemical enhancement mechanism and how to separate the chemical enhancement mechanism from electromagnetic enhancement mechanism..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3087 (2015)
Preparation of Gold Nano-Particles as Surface-Enhanced Raman Scattering Sensors for Analysis of Banned Food Dye Chrysoidin in Yuba
XU Xue-qin, LIU Qiong-hua, YANG Fang, QIAN Jiang, CHEN Jian, LIN Zhen-yu, and QIU Bin
Chrysoidin is a kind of banned food dye, and it has been illegally used for coloring food. A rapid detection and quantification method is developed and applied in analysis chrysoidin in yuba. Gold nanoparticles are synthesized by using hexadecyl trimethyl ammonium bromide (CTAB) as the bifunctional ligand to link the sChrysoidin is a kind of banned food dye, and it has been illegally used for coloring food. A rapid detection and quantification method is developed and applied in analysis chrysoidin in yuba. Gold nanoparticles are synthesized by using hexadecyl trimethyl ammonium bromide (CTAB) as the bifunctional ligand to link the solid substrate and the AuNPs. The laser wavelength used for quantitative is 1 594 cm-1. Significant differences between different concentrations of chrysoidin are verified by multiple variable analysis. A relationship between the logarithm of the concentrations and the intensity of laser is proved using univariate analysis method. The calibration curves showed good linearity in the range of 0.001～0.5 mmol·L-1 with correlation coefficients r=0.995. The method is successfully applied to the determination of chrysoidin in yuba. The average recoveries of the drugs spiked at 50 and 500 μg·g-1 levels are 82.4% and 116.9%, and the relative standard deviations (RSD) are 3.8% and 4.0%. The method is simple, rapid, sensitive and accurate in the determination of chrysoidin..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3092 (2015)
Development of Fluorescence Resonance Energy Transfer Sensor for Determination of Adenosine Monophosphate in Biological Drug
DONG Ling-yu, DU Hong-ming, WANG Peng, WANG Li-yun, LI Yi-ke, ZHAI Hong, FENG Ting, WANG Xiang-feng, ZHU Qiao-you, and XIE Meng-xia
The biological drug of the calf-blood dialysate has various pharmacological effects. It can promote the oxygen and glucose uptake for the hypoxia cells, and has beneficial effects on the malfunction of the blood circulation and trophic disturbances in the brain, and the impairment of peripheral blood circulation. FurthThe biological drug of the calf-blood dialysate has various pharmacological effects. It can promote the oxygen and glucose uptake for the hypoxia cells, and has beneficial effects on the malfunction of the blood circulation and trophic disturbances in the brain, and the impairment of peripheral blood circulation. Furthermore, it is favorable to wound healing and can regulate the central nervous system. Adenosine monophosphate (AMP) is a main active ingredient of the biological drug. In this report, a fluorescence resonance energy transfer (FRET) sensor has been developed with β-CD-capped ZnS QDs as energy donor and 3-hydroxyflavone (3-HF) as energy acceptor. The results showed that AMP can lead to the fluorescence quenching of the FRET sensor at 526 nm, and the Stern-Volmer curve between the fluorescence quenching and the concentrations of AMP present a satisfactory linearity with the correlation coefficient of 0.996. The developed sensor has successfully applied for determination of the AMP in the biological drug..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3096 (2015)
Fluoroimmunoassay and Magnetic Lateral Flow Immunoassay for the Detection of Ractopamine
WANG Song-bai, ZHANG Yan, WEI Yan-li, AN Wen-ting, WANG Yu, and SHUANG Shao-min
A fluoroimmunoassay based on quantum dots（QDs） and a lateral flow immunoassay system based on the magnetic beads (MB) were constructed to detect ractopamine (RAC) in urine samples. The monoclonal antibody (Ab1) against RAC was conjugated with QDs or MB as detector reagent, respectively. They apply a competitive format A fluoroimmunoassay based on quantum dots（QDs） and a lateral flow immunoassay system based on the magnetic beads (MB) were constructed to detect ractopamine (RAC) in urine samples. The monoclonal antibody (Ab1) against RAC was conjugated with QDs or MB as detector reagent, respectively. They apply a competitive format using an immobilized RAC conjugate and free RAC present in samples. That is to say, the concentration of RAC in the sample was negative related to the fluorescense intensity of QDs or the color density of MB. Results showed that the limit of detection (LOD) of fluorescence immunoassay method is 1 ng·mL-1 and analysis time is 4 h, while the visual LOD was 10 ng·mL-1 and analysis time was 15 min in magnetic lateral flow immunoassay system (MFLIS). Taken into consideration of the advantages and disadvantages of the two methods, it was suitable for the trace detection of RAC using fluoroimmunoassay while it was appropriate for point-of-care tesing of RAC by MFLIS..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3100 (2015)
Fluorescent and Magnetic Relaxation Switch Immunosensor for the Detecting Foodborne Pathogen Salmonella enterica in Water Samples
WANG Song-bai, ZHANG Yan, AN Wen-ting, WEI Yan-li, WANG Yu, and SHUANG Shao-min
Fluoroimmunoassay based on quantum dots（QDs） and magnetic relaxation switch (MRS) immunoassay based on superparamagnetic nanoparticles（SMN） were constructed to detect Salmonella enterica（S. enterica） in water samples. In fluoroimmunoassay, magnetic beads was conjugated with S. enterica capture antibody （MB-Ab2） to enriFluoroimmunoassay based on quantum dots（QDs） and magnetic relaxation switch (MRS) immunoassay based on superparamagnetic nanoparticles（SMN） were constructed to detect Salmonella enterica（S. enterica） in water samples. In fluoroimmunoassay, magnetic beads was conjugated with S. enterica capture antibody （MB-Ab2） to enrich S. enterica from sample solution, then the QDs was conjugated with the S. enterica detection antibody (QDs-Ab1) to detect S. enterica based on sandwich immunoassay format. And the fluorescence intensity is positive related to the bacteria concentration of the sample. Results showed that the limit of detection (LOD) of this method was 102 cfu·mL-1 and analysis time was 2 h. In MRS assay, magnetic nanoparticle-antibody conjugate (MN-Ab1) can switch their dispersed and aggregated state in the presence of the target. This state of change can modulate the spin-spin relaxation time (T2) of the neighboring water molecule. The change in T2 (ΔT2) positively correlates with the amount of the target in the sample. Thus, ΔT2 can be used as a detection signal in MRS immunosensors. Results showed that LOD of MRS sensor for S. enterica was 103 cfu·mL-1 and analysis time was 0.5 h. Two methods were compared in terms of advantages and disadvantages in detecting S. enterica..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3105 (2015)
The Thiacalix［4］arene-Coumarin Fluorescence Probe Recognition for Fe3+ and Bovine Hemoglobin
LI Yan-qin, MU Lan, ZENG Xi, LI Jun, and Takehiko Yamato
1,3-alternate coumarin substituted thiacalix［4］arene fluorescent probe 1 was synthesised from 1,3-alternate diethyl thiacalix［4］arene and 7-hydroxycoumarin by-step reactions. In DMSO/H2O (φ, 3/7, pH 7) solution, the strong fluorescence emission and UV absorption of probe 1 can be selectively quenched or significantly e1,3-alternate coumarin substituted thiacalix［4］arene fluorescent probe 1 was synthesised from 1,3-alternate diethyl thiacalix［4］arene and 7-hydroxycoumarin by-step reactions. In DMSO/H2O (φ, 3/7, pH 7) solution, the strong fluorescence emission and UV absorption of probe 1 can be selectively quenched or significantly enhanced by Fe3+ ion. The probe 1 showed high Fe3+ selective fluorescence quenching or absorption enhancement over commonly coexistent metal ions in neutral aqueous media, and the limit of detections were obtained as low as 10－8 mol·L-1 of Fe3+ by fluorescence and absorption spectrometry. Spectral titration, isothermal titration calorimetry and mass spectrometry were showed that probe and Fe3+ form 1∶1 complexes, the constant up to 105 L·mol-1 and coordinate process was spontaneous by the mole binding free energy and entropy of probe with Fe3+. In addition, the probe can identification bovine hemoglobin (BHb) over other proteins through quenched its fluorescence in DMSO/H2O (φ, 1/9, Tris-HCl, pH 7, 0.1 mol·L-1 NaCl) media. The limit of detection was obtained as 0.12 μg·mL-1 of BHb, as well as a linearity of 0.2～3.0 μg·mL-1, indicating the probe of high sensitivity and quantitation range. It can be used as a selective recognition Fe3+ and BHb of thiacalix<参考文献原文>arene fluorescent probe..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3111 (2015)
Effect of Temperatures and Lead Ions on 3D-EEMs of Dissolved Organic Matter (DOM) Derived from Straw Humification
FAN Chun-hui, ZHANG Ying-chao, and WANG Jia-hong
Straw incorporation is significant for straw reduction and reutilization, and is clearly required in the twelfth five-year-plan for national economic and social development of the People’s Republic of China. The incorporated straw will naturally decompose and release the component of dissolved organic matter (DOM). At Straw incorporation is significant for straw reduction and reutilization, and is clearly required in the twelfth five-year-plan for national economic and social development of the People’s Republic of China. The incorporated straw will naturally decompose and release the component of dissolved organic matter (DOM). At present, it lacks the research on straw humification behavior controlled by environmental factors and complexation effect between humification component and metal ions with fluorescence spectrometry in the representative region of loess. The fluorescence spectrometry was used to reveal the 3D-EEMs characteristics of DOM affected by temperatures and lead ions in the straw humification process, and the modified Stern-Volmer equation and Van’t Hoff equation were applied to indicate the complexation parameters and thermodynamic constants between lead ions and DOM. The results showed: the humification temperatures affected little on fluorescence peaks of DOM and no peaks were obviously found to appear or disappear from the 3D-EEMs results. The fluorescence intensity decreased gradually at higher temperatures and in the presence of lead ions, the quenching effect might work in the process. The binding ability was more significant between lead ions and visible fulvic-like component shown from modified Stern-Volmer equation, and the values of f revealed the complexation effect of lead ions and functional groups in DOM. Static quenching was the primary mechanism during the reaction process. The constants in Van’t Hoff equation suggested the reaction was spontaneous and endothermic, and the disordered degree and the complexity were relatively low in the reaction system. The 3D-EEMs were acceptable to illustrate the variation of DOM characteristics under different temperatures and in the presence of lead ions in the straw humification process..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3117 (2015)
Study of Retrieving the Sandy Surface Roughness Land Based on the Bidirectional Reflectance Model
L Yun-feng, and ZHAO Yun-sheng
In the semiarid area, the structural nature of sandy land is changed due to wind erosion. Furthermore, assessing the changes in the composition and surface roughness in several spatial and temporal scales is significant for the wind erosion model calculations. As a noninvasive approach, remote sensing can be used to imIn the semiarid area, the structural nature of sandy land is changed due to wind erosion. Furthermore, assessing the changes in the composition and surface roughness in several spatial and temporal scales is significant for the wind erosion model calculations. As a noninvasive approach, remote sensing can be used to improve the study of sandy surface in time and space. In order to characterize the surface structure using the reflectance of sandy land, we analysis the effects of the changes of sandy surface structure on the bidirectional reflectance distribution basing on the multi-angular and hyperspectral measurements in the field; the measured sandy land samples are taken from nature, but the surface structures are artificial: one type is the direction of sand furrows is parallel to the incident direction, the other is the direction of sand furrows is perpendicular to the incident direction. At the same time, we analyzed the effects of surface structure on the bidirectional reflectance factor of sand land and we also retrieve the sandy surface roughness using the reflectance model parameter. The results suggest that both types of sand furrows will influence the distribution of reflectance of sandy land surface, for example, the backward scattering of sandy land increased when the direction of sand furrows is perpendicular to the incident direction, and the range of backward scattering of sandy land expended when the direction of sand furrows is parallel to the incident direction. When we compared the measured reflectance with the modeled results basing on the reflectance model, it is found that the reflectance model can be used to simulate the reflectance property of sandy land surface and prove that the parameter of model is useful for retrieving the surface roughness. This research not only presents the sample for quantifying the structural information of sandy land by the reflectance measurements, but also shows valuable reference for the research of intrinsic optical property of sandy land and the reversion of the texture of sandy land. In other words, this paper can also help the scientists understand the effect of the structural information on the optical properties of sandy land..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3123 (2015)
A Novel Method of Soil Moisture Content Monitoring by Land Surface Temperature and LAI
GAO Zhong-ling, ZHENG Xiao-po, SUN Yue-jun, and WANG Jian-hua
Land surface temperature (Ts) is influenced by soil background and vegetation growing conditions, and the combination of Ts and vegetation indices (Vis) can indicate the status of surface soil moisture content (SMC). In this study, Advanced Temperature Vegetation Dryness Index (ATVDI) used for monitoring SMC was proposLand surface temperature (Ts) is influenced by soil background and vegetation growing conditions, and the combination of Ts and vegetation indices (Vis) can indicate the status of surface soil moisture content (SMC). In this study, Advanced Temperature Vegetation Dryness Index (ATVDI) used for monitoring SMC was proposed on the basis of the simulation results with agricultural climate model CUPID. Previous studies have concluded that Normalized Difference Vegetation Index (NDVI) easily reaches the saturation point, andLeaf Area Index (LAI) was then used instead of NDVI to estimate soil moisture content in the paper. With LAI-Ts scatter diagram established by the simulation results of CUPID model, how Ts varied with LAI and SMC was found. In the case of the identical soil background, the logarithmic relations between Ts and LAI were more accurate than the linear relations included in Temperature Vegetation Dryness Index (TVDI), based on which ATVDI was then developed. LAI-Ts scatter diagram with satellite imagery were necessary for determining the expression of the upper and lower logarithmic curves while ATVDI was used for monitoring SMC. Ts derived from satellite imagery were then transformed to the Tsvalue which has the same SMC and the minimum LAI in study area with look–up table. The measured SMC from the field sites in Weihe Plain, Shanxi Province, China, and the products of LAI and Ts (MOD15A2 and MOD11A2, respectively) produced by the image derived from Moderate Resolution Imaging Spectrometer (MODIS) were collected to validate the new method proposed in this study. The validation results shown that ATVDI (R2=0.62) was accurate enough to monitor SMC, and it achieved better result than TVDI.Moreover, ATVDI-derived result were Ts values with some physical meanings, which made it comparative in different periods. Therefore, ATVDI is a promising method for monitoring SMC in different time-spatial scales in agricultural fields..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3129 (2015)
Interaction of Cucurbit［8］uril with β-Indoleacetic Acid and Methylviologen
SONG Gui-xian, TANG Qing, HUANG Ying, ZHANG Jian-xin, TAO Zhu, XUE Sai-feng, ZHU Qian-jiang, and WEI Gang
The interaction between Qwith β-indoleacetic acid and the methylviologen was studied in aqueous solution with electronic absorption spectroscopy (UV-Vis), fluorescence spectroscopy, 1H NMR spectroscopy and isothermal titration calorimetry (ITC) in details. The authors explored the mode of action, action site and thermoThe interaction between Q<参考文献原文>with β-indoleacetic acid and the methylviologen was studied in aqueous solution with electronic absorption spectroscopy (UV-Vis), fluorescence spectroscopy, 1H NMR spectroscopy and isothermal titration calorimetry (ITC) in details. The authors explored the mode of action, action site and thermodynamic properties of the host-guest system. The electronic absorption and fluorescence spectroscopy data showed that the Q［8］/IAA system and Q［8］/MV2+ system informed 1∶1 inclusion complexes in aqueous solution. ITC results showed that the changes of Gibbs free energy and enthalpy are all negative, it suggested that complex formation was spontaneous and exothermic reaction. Moreover, ITC results for the Q<参考文献原文>and IAA with MV2+ indicate that the association constants of the Q［8］-IAA and Q［8］-MV2+ complexes were (3.22±0.96)×105 L·mol-1 and (3.90±0.91)×106 L·mol-1, respectively. Therefore, the interaction between Q<参考文献原文>and IAA with the MV2+ was a competitive process. This likely occurs because the MV2+ and IAA molecules attempt to occupy the Q<参考文献原文>cavity, which reduces the fluorescence and absorption spectra intensity of Q［8］-IAA because of the formation of a new inclusion complex between Q<参考文献原文>and IAA with MV2+. In addition, with the addition of MV2+ to a Q［8］/IAA complex, 1H NMR results showed that the indole moieties of β-indoleacetic acid and bipyridyl group of methylviologen can be incorporated into Q<参考文献原文>cavities because of electronic transfer MV2+ with PQ in a Q<参考文献原文>cavity with ternary complexes. These results provides the potential applications for the supramolecular self-assembly in cucurbit［n］urils field..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3134 (2015)
Prediction of Cadmium Content in the Leaves of Navel Orange in Heavy Metal Contaminated Soil Using VIS-NIR Reflectance Spectroscopy
SHI Rong-jie, PAN Xian-zhang, WANG Chang-kun, LIU Ya, LI Yan-li, and LI Zhi-ting
Visual and Near-infrared (VIS-NIR) reflectance spectroscopy had been used widely in monitoring agricultural pollution in recent years, however, it was rarely applied in monitoring the contamination of heavy metal in orchards. In the present paper, Newhall navel orange (Citrus sinensis ［L.］ Osbeck cv. Newhall) were cultVisual and Near-infrared (VIS-NIR) reflectance spectroscopy had been used widely in monitoring agricultural pollution in recent years, however, it was rarely applied in monitoring the contamination of heavy metal in orchards. In the present paper, Newhall navel orange (Citrus sinensis ［L.］ Osbeck cv. Newhall) were cultivated in the potted soil contaminated with cadmium(Cd) at different levels, and the spectral reflectance and Cd content in the leaves were measured simultaneously at different growing seasons, which then were used to establish the prediction model by partial least squares regression (PLSR) based on spectral reflectance and by linear regression based on spectral index. The results showed that Cd was more easily transferred to and cumulated in the new leaves, and this phenomenon was more obvious in heavily contaminated soils with Cd. Blue shift in red edge was found in the band of 700～730 nm in the new leaves, however, no such phenomenon was found in the old leaves. The coefficient of determination (R2) of linear regression model based on spectral index was nearly 0.8, while the PLSR model had a better result in predicting Cd content in the new leaves than the linear regression with R2CV of approximately 0.9. Furthermore, the standard normal variate transformation（SNV）in spectral preprocessing can improve the precision significantly in PLSR model. These results suggest that the VIS-NIR method has a great potential in monitoring heavy metal pollution in the navel orange..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3140 (2015)
Influence Mechanism of Dissolved Organic Matter (DOM) from Straw Humification on Chemical Speciation of Lead in Loess Region
FAN Chun-hui, ZHANG Ying-chao, and WANG Jia-hong
Heavy metal is regarded as one of the most representative contaminants in soil, and the chemical speciation is greatly related to the toxicity and transformation behavior, which attracts the attention of researchers for years. The environmental factors could change the speciation of heavy metals, plus to the complexityHeavy metal is regarded as one of the most representative contaminants in soil, and the chemical speciation is greatly related to the toxicity and transformation behavior, which attracts the attention of researchers for years. The environmental factors could change the speciation of heavy metals, plus to the complexity of soil system, and the transformation variation of speciation might occasional existed under similar conditions. At present, the different viewpoints of related issues are urgent to be investigated. The characteristics of DOM from straw humification were revealed with UV spectra, 3D-EEMs spectra and FTIR spectra, and the Tessier Sequential Extraction Procedure was used to study the speciation transformation behavior of lead affected by DOM. The linear relationship of the contents between DOC and lead bound to organic matter was indicated to further discuss the influence mechanism of lead speciation using FTIR. The results showed: the absorbance peak of DOM located in 229 nm in UV spectra, and the fluorescence peaks appeared around the regions of λex/em=250/350 nm, λex/em=250/450 nm and λex/em=330/450 nm, referred as UV fulvic-like fluorescence, and visible humic-like fluorescence, respectively. The dominant functional groups of DOM included —OH, CO and N—H. The three fractions contents of lead (exchangeable, bound to iron and manganese oxides, residual) decreased, while that of lead bound to carbonates varied little. The contents of DOC and lead bound to organic matter appeared positive correlation (r=0.691 8), indicating the effective complexation between DOM and lead ions. The functional groups of —OH, CO and —COOH played an important role for the speciation transformation of lead, suggested from the FTIR spectra..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3146 (2015)
Sensing of Cu2+ Based on Fenton Reaction and Unmodified Gold Nanoparticles
XING Yun-peng, LIU Chun, ZHOU Xiao-hong, ZHANG Li-pei, and SHI Han-chang
Heavy metal pollution has received great attentions in recent years. The traditional methods for heavy metal detection rely on the expensive laboratory instruments and need time-consuming preparation steps; therefore, it is urgent to develop quick and highly sensitive new technologies for heavy metal detection. The colHeavy metal pollution has received great attentions in recent years. The traditional methods for heavy metal detection rely on the expensive laboratory instruments and need time-consuming preparation steps; therefore, it is urgent to develop quick and highly sensitive new technologies for heavy metal detection. The colorimetric method based on the gold nanoparticles (AuNPs) features with simple operation, high sensitivity and low cost, therefore, enabling it widely concerned and used in the environmental monitoring, food safety and chemical and biological sensing fields. This work developed a simple, rapid and highly sensitive strategy based on the Fenton reaction and unmodified AuNPs for the detection of Cu2+ in water samples. The hydroxyl radical (·OH) generated by the Fenton reaction between the Cu2+ and sodium ascorbate (SA) oxidized the single stranded DNA (ssDNA) attached on the AuNPs surface into variable sequence fragments. The cleavage of ssDNA induced the aggregation of AuNPs in a certain salt solution, therefore, resulting in the changes on the absorbance of solution. The assay conditions were optimized to be pH value of 7.9, 11 mg·L-1 ssDNA, 8 mmol·L-1 SA and 70 mmol·L-1 NaCl. Results showed that the absorbance ratio values at the wavelengths of 700 and 525 nm (A700/A525) were linearly correlated with the Cu2+ concentrations. The linear detection range was 0.1～10.0 μmol·L-1 with a detection limit of 24 nmol·L-1 (3σ). Spiked recoveries ranged from 87%～120% in three sorts of water, including drinking water, tap water and lake water, which confirmed that the potentials of the proposed assay for Cu2+ detection in reality..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3151 (2015)
Optimized Spectral Indices Based Estimation of Forage Grass Biomass
AN Hai-bo, LI Fei, ZHAO Meng-li, and LIU Ya-jun
As an important indicator of forage production, aboveground biomass will directly illustrate the growth of forage grass. Therefore, Real-time monitoring biomass of forage grass play a crucial role in performing suitable grazing and management in artificial and natural grassland. However, traditional sampling and measurAs an important indicator of forage production, aboveground biomass will directly illustrate the growth of forage grass. Therefore, Real-time monitoring biomass of forage grass play a crucial role in performing suitable grazing and management in artificial and natural grassland. However, traditional sampling and measuring are time-consuming and labor-intensive. Recently, development of hyperspectral remote sensing provides the feasibility in timely and nondestructive deriving biomass of forage grass. In the present study, the main objectives were to explore the robustness of published and optimized spectral indices in estimating biomass of forage grass in natural and artificial pasture. The natural pasture with four grazing density (control, light grazing, moderate grazing and high grazing) was designed in desert steppe, and different forage cultivars with different N rate were conducted in artificial forage fields in Inner Mongolia. The canopy reflectance and biomass in each plot were measured during critical stages. The result showed that, due to the influence in canopy structure and biomass, the canopy reflectance have a great difference in different type of forage grass. The best performing spectral index varied in different species of forage grass with different treatments (R2=0.00~0.69). The predictive ability of spectral indices decreased under low biomass of desert steppe, while red band based spectral indices lost sensitivity under moderate-high biomass of forage maize. When band combinations of simple ratio and normalized difference spectral indices were optimized in combined datasets of natural and artificial grassland, optimized spectral indices significant increased predictive ability and the model between biomass and optimized spectral indices had the highest R2 (R2=0.72) compared to published spectral indices. Sensitive analysis further confirmed that the optimized index had the lowest noise equivalent and were the best performing index in estimating biomass. In conclusion, optimizing wavebands combination was a promising algorithm for improving prediction abilities of biomass for forage grass..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3155 (2015)
Spectral Analysis of CdZnSe Ternary Quantum Dots Sensitized TiO2 Tubes and Its Application in Visible-Light Photocatalysis
HAN Zhi-zhong, REN Li-li, PAN Hai-bo, LI Chun-yan, CHEN Jing-hua, and CHEN Jian-zhong
In this work, cadmium nitrate hexahydrate ［Cd(NO3)2·6H2O］ is as a source of cadmium, zinc nitrate ［Zn(NO3)2］ as a source of zinc source, and NaHSe as a source of selenium which was prepared through reducing the elemental selenium with sodium borohydride (NaBH4). Then water-soluble Cd1-xZnxSe ternary quantum dots wIn this work, cadmium nitrate hexahydrate ［Cd(NO3)2·6H2O］ is as a source of cadmium, zinc nitrate ［Zn(NO3)2］ as a source of zinc source, and NaHSe as a source of selenium which was prepared through reducing the elemental selenium with sodium borohydride (NaBH4). Then water-soluble Cd1-xZnxSe ternary quantum dots with different component were prepared by colloid chemistry. The as-prepared Cd1-xZnxSe ternary quantum dots exhibit stable fluorescent property in aqueous solution, and can still maintain good dispersivity at room temperature for four months. Powder X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM) were used to analyze crystal structure and morphology of the prepared Cd1-xZnxSe. It is found that the as-prepared ternary quantum dots are cubic phase, show as sphere, and the average of particle size is approximate 4 nm. The spectral properties and energy band structure of the as-prepared ternary quantum dots were modulated through changing the atom ratio of elements Zn and Cd. Compared with binary quantum dots CdSe and ZnSe, the ultraviolet-visible (UV-Visible) absorption spectrum and fluorescence (FL) emission spectrum of ternary quantum dots are both red-shift. The composites (Cd0.5Zn0.5Se@TNTs) of Cd0.5Zn0.5Se ternary quantum dots and TiO2 nanotubes (TNTs) were prepared by directly immerging TNTs into quantum dots dispersive solution for 5 hours. TEM image shows that the Cd0.5Zn0.5Se ternary quantum dots were closely combined to nanotube surface. The infrared spectra show that the Ti-Se bond was formed between Cd0.5Zn0.5Se ternary quantum dots and TiO2 nanotubes, which improve the stability of the composite. Compared to pristine TNTs, UV-Visible absorption spectrum of the composites is significantly enhanced in the visible region of light. And the absorption band edge of Cd0.5Zn0.5Se@TNTs red-shift from 400 to 700 nm. The recombination of the photogenerated electron-hole pairs was restrained with the as-prepared ternary quantum dots. Therefore, the visible-light photocatalytic efficiency was greatly improved. After visible-light irradiation for 60 min, the degradation of Cd0.5Zn0.5Se@TNTs photocatalysts for RhB is nearly 100%, which is about 3.3 times of that of pristine TNTs and 2.5 times of that of pure Cd0.5Zn0.5Se ternary quantum dots, respectively..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3161 (2015)
Detection of Hawthorn Fruit Defects Using Hyperspectral Imaging
LIU De-hua, ZHANG Shu-juan, WANG Bin, YU Ke-qiang, ZHAO Yan-ru, and HE Yong
Hyperspectral imaging technology covered the range of 380～1 000 nm was employed to detect defects (bruise and insect damage) of hawthorn fruit. A total of 134 samples were collected, which included damage fruit of 46, pest fruit of 30, injure and pest fruit of 10 and intact fruit of 48. Because calyx·s-1tem-end anHyperspectral imaging technology covered the range of 380～1 000 nm was employed to detect defects (bruise and insect damage) of hawthorn fruit. A total of 134 samples were collected, which included damage fruit of 46, pest fruit of 30, injure and pest fruit of 10 and intact fruit of 48. Because calyx·s-1tem-end and bruise/insect damage regions offered a similar appearance characteristic in RGB images, which could produce easily confusion between them. Hence, five types of defects including bruise, insect damage, sound, calyx, and stem-end were collected from 230 hawthorn fruits. After acquiring hyperspectral images of hawthorn fruits, the spectral data were extracted from region of interest(ROI). Then, several pretreatment methods of standard normalized variate (SNV), savitzky golay (SG), median filter(MF) and multiplicative scatter correction (MSC) were used and partial least squares method(PLS) model was carried out to obtain the better performance. Accordingly to their results, SNV pretreatment methods assessed by PLS was viewed as best pretreatment method. Lastly, SNV was chosen as the pretreatment method. Spectral features of five different regions were combined with Regression coefficients(RCs) of partial least squares-discriminant analysis (PLS-DA) model was used to identify the important wavelengths and ten wavebands at 483, 563, 645, 671, 686, 722, 777, 819, 837 and 942 nm were selected from all of the wavebands. Using Kennard-Stone algorithm, all kinds of samples were randomly divided into training set (173) and test set (57) according to the proportion of 3∶1. And then, least squares-support vector machine (LS-SVM) discriminate model was established by using the selected wavebands. The results showed that the discriminate accuracy of the method was 91.23%. In the other hand, images at ten important wavebands were executed to Principal component analysis (PCA). Using “Sobel” operator and region growing algrorithm “Regiongrow”, the edge and defect feature of 86 Hawthorn could be recognized. Lastly, the detect precision of bruised, insect damage and two-defect samples is 95.65%, 86.67% and 100%, respectively. This investigation demonstrated that hyperspectral imaging technology could detect the defects of bruise, insect damage, calyx, and stem-end in hawthorn fruit in qualitative analysis and feature detection. which provided a theoretical reference for the defects nondestructive detection of hawthorn fruit..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3167 (2015)
Study on the Geochemical Anomalies Identification of REE Based on HJ-1A-HSI
CHEN Yong-gan, WANG Mei-juan, and LI Peng
The characteristic spectral bands of REE do not vary with the occurrence state, cannot be used to identify mineral species, but can prove the existence of its own. Here we report the spectrum characteristics of REE and their compounds by remote sensing wave bandfrom visible light-near infrared, with the quantitative reThe characteristic spectral bands of REE do not vary with the occurrence state, cannot be used to identify mineral species, but can prove the existence of its own. Here we report the spectrum characteristics of REE and their compounds by remote sensing wave bandfrom visible light-near infrared, with the quantitative relationship between the contents of REE and absorption index of characteristic spectral bands. The experimental study was carried out in Bayan Obo area, Inner Mongolia. Spectrums and Nd contents of typical rock and ore samples were gathered and analyzed. There is positive correlation between the Nd content, the absorption depth and absorption index of different spectrum characteristics (correlation coefficient >0.778). Moreover, the correlation between absorption index of 726~772 nm band and Nd content is the best, at 0.937. As mentioned above, the quantitative model and the inversion information remote sensing geochemical anomaly of Nd were built by the band of HJ-1A-HIS hyperspectral remote sensing data. Our results consistent with 1∶200 000 stream sediment geochemical anomalies of Nd. The model provides a new means for rapid extract regional geochemical anomalies of REE..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3172 (2015)
Retrieval of Copper Pollution Information from Hyperspectral Satellite Data in a Vegetation Cover Mining Area
QU Yong-hua, JIAO Si-hong, LIU Su-hong, and ZHU Ye-qing
Heavy metal mining activities have caused the complex influence on the ecological environment of the mining regions. For example, a large amount of acidic waste water containing heavy metal ions have be produced in the process of copper mining which can bring serious pollution to the ecological environment of the regioHeavy metal mining activities have caused the complex influence on the ecological environment of the mining regions. For example, a large amount of acidic waste water containing heavy metal ions have be produced in the process of copper mining which can bring serious pollution to the ecological environment of the region. In the previous research work, bare soil is mainly taken as the research target when monitoring environmental pollution, and thus the effects of land surface vegetation have been ignored. It is well known that vegetation condition is one of the most important indictors to reflect the ecological change in a certain region and there is a significant linkage between the vegetation spectral characteristics and the heavy metal when the vegetation is effected by the heavy metal pollution. It means the vegetation is sensitive to heavy metal pollution by their physiological behaviors in response to the physiological ecology change of their growing environment. The conventional methods, which often rely on large amounts of field survey data and laboratorial chemical analysis, are time consuming and costing a lot of material resources. The spectrum analysis method using remote sensing technology can acquire the information of the heavy mental content in the vegetation without touching it. However, the retrieval of that information from the hyperspectral data is not an easy job due to the difficulty in figuring out the specific band, which is sensitive to the specific heavy metal, from a huge number of hyperspectral bands. Thus the selection of the sensitive band is the key of the spectrum analysis method. This paper proposed a statistical analysis method to find the feature band sensitive to heavy metal ion from the hyperspectral data and to then retrieve the metal content using the field survey data and the hyperspectral images from China Environment Satellite HJ-1. This method selected copper ion content in the leaves as the indicator of copper pollution level, using stepwise multiple linear regression and cross validation on the dataset which is consisting of 44 groups of copper ion content information in the polluted vegetation leaves from Dexing Copper Mine in Jiangxi Province to build up a statistical model by also incorporating the HJ-1 satellite images. This model was then used to estimate the copper content distribution over the whole research area at Dexing Copper Mine. The result has shown that there is strong statistical significance of the model which revealed the most sensitive waveband to copper ion is located at 516 nm. The distribution map illustrated that the copper ion content is generally in the range of 0～130 mg·kg-1 in the vegetation covering area at Dexing Copper Mine and the most seriously polluted area is located at the South-east corner of Dexing City as well as the mining spots with a higher value between 80 and 100 mg·kg-1. This result is consistent with the ground observation experiment data. The distribution map can certainly provide some important basic data on the copper pollution monitoring and treatment..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3176 (2015)
Prediction of Encapsulation Temperatures of Copolymer Films in Photovoltaic Cells Using Hyperspectral Imaging Techniques and Chemometrics
LIN Ping, CHEN Yong-ming, and YAO Zhi-lei
A novel method of combination of the chemometrics and the hyperspectral imaging techniques was presented to detect the temperatures of Ethylene-Vinyl Acetate copolymer (EVA) films in photovoltaic cells during the thermal encapsulation process. Four varieties of the EVA films which had been heated at the temperatures ofA novel method of combination of the chemometrics and the hyperspectral imaging techniques was presented to detect the temperatures of Ethylene-Vinyl Acetate copolymer (EVA) films in photovoltaic cells during the thermal encapsulation process. Four varieties of the EVA films which had been heated at the temperatures of 128, 132, 142 and 148 ℃ during the photovoltaic cells production process were used for investigation in this paper. These copolymer encapsulation films were firstly scanned by the hyperspectral imaging equipment (Spectral Imaging Ltd. Oulu, Finland). The scanning band range of hyperspectral equipemnt was set between 904.58 and 1 700.01 nm. The hyperspectral dataset of copolymer films was randomly divided into two parts for the training and test purpose. Each type of the training set and test set contained 90 and 10 instances, respectively. The obtained hyperspectral images of EVA films were dealt with by using the ENVI (Exelis Visual Information Solutions, USA) software. The size of region of interest (ROI) of each obtained hyperspectral image of EVA film was set as 150×150 pixels. The average of reflectance hyper spectra of all the pixels in the ROI was used as the characteristic curve to represent the instance. There kinds of chemometrics methods including partial least squares regression (PLSR), multi-class support vector machine (SVM) and large margin nearest neighbor (LMNN) were used to correlate the characteristic hyper spectra with the encapsulation temperatures of of copolymer films. The plot of weighted regression coefficients illustrated that both bands of short- and long-wave near infrared hyperspectral data contributed to enhancing the prediction accuracy of the forecast model. Because the attained reflectance hyperspectral data of EVA materials displayed the strong nonlinearity, the prediction performance of linear modeling method of PLSR declined and the prediction precision only reached to 95%. The kernel-based forecast models were introduced to eliminate the impact of nonlinear hyperspectral data to some extent through mapping the original nonlinear hyperspectral data to the high dimensional linear feature space, so the relationship between the nonlinear hyperspectral data and the encapsulation temperatures of EVA films was fully disclosed finally. Compared with the prediction results of three proposed models, the prediction performance of LMNN was superior to the other two, whose final recognition accuracy achieved 100%. The results indicated that the methods of combination of LMNN model with the hyperspectral imaging techniques was the best one for accurately and rapidly determining the encapsulation temperatures of EVA films of photovoltaic cells. In addition, this paper had created the ideal conditions for automatically monitoring and effectively controlling the encapsulation temperatures of EVA films in the photovoltaic cells production process..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3182 (2015)
Analysis of X-Ray Fluorescence Spectroscopy and Plasma Mass Spectrometry of Pangxidong Composite Granitoid Pluton and Its Implications for Magmatic Differentiation
ZENG Chang-yu, DING Ru-xin, LI Hong-zhong, ZHOU Yong-zhang, NIU Jia, and ZHANG Jie-tang
Pangxidong composite granitoid pluton located in the southwestern margin of Yunkai massif. The metamorphic grade of this pluton increases from outside to inside, that is, banded-augen granitic gneisses, gneissoid granites and granites distribute in order from edge to core. X-Ray Fluorescence Spectroscopy and Plasma MasPangxidong composite granitoid pluton located in the southwestern margin of Yunkai massif. The metamorphic grade of this pluton increases from outside to inside, that is, banded-augen granitic gneisses, gneissoid granites and granites distribute in order from edge to core. X-Ray Fluorescence Spectroscopy and Plasma Mass Spectrometry are conducted to study the geochemical characteristics of the three types of rocks. The result shows that all the three types of rocks are peraluminous rocks and their contents of main elements and rare earth elements change gradually. From granitic gneisses to granites, the contents of Al2O3, CaO, MgO, TiO2, total rare earth elements and light rare earth elements increase, but the contents of SiO2 and heavy rare earth elements decrease. It is suggested that the phylogenetic relationship exists between granitic gneisses, gneissoid granites and granites during the multi-stage tectonic evolution process. Furthermore, the remelting of metamorphosed supracrustal rocks in Yunkai massif is probably an important cause of granitoid rocks forming. The evolutionary mechanism is probably that SiO2 and heavy rare earth elements were melt out from the protolith and gradually enriched upward, but Al2O3, CaO, MgO, TiO2 and light rare earth elements enriched downward..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3187 (2015)
Determination of Heavy Metal Elements in Diatomite Filter Aid by Inductively Coupled Plasma Mass Spectrometry
NIE Xi-du, and FU Liang
This study established a method for determining Be, Cr, Ni, As, Cd, Sb, Sn, Tl, Hg and Pb, total 10 heavy metals in diatomite filter aid. The diatomite filter aid was digested by using the mixture acid of HNO3+HF+H3PO4 in microwave system, 10 heavy metals elements were determined by inductively coupled plasma mass specThis study established a method for determining Be, Cr, Ni, As, Cd, Sb, Sn, Tl, Hg and Pb, total 10 heavy metals in diatomite filter aid. The diatomite filter aid was digested by using the mixture acid of HNO3+HF+H3PO4 in microwave system, 10 heavy metals elements were determined by inductively coupled plasma mass spectrometry (ICP-MS). The interferences of mass spectrometry caused by the high silicon substrate were optimized, first the equipment parameters and isotopes of test metals were selected to eliminate these interferences, the methane was selected as reactant gas, and the mass spectral interferences were eliminated by dynamic reaction cell (DRC). Li, Sc, Y, In and Bi were selected as the internal standard elements to correct the interferences caused by matrix and the drift of sensitivity. The results show that the detection limits for analyte is in the range of 3.29～15.68 ng·L-1, relative standard deviations (RSD) is less than 4.62%, and the recovery is in the range of 90.71%～107.22%. The current method has some advantages such as, high sensitivity, accurate, and precision, which can be used in diatomite filter aid quality control and safety estimations..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3192 (2015)
Application of ICP-MS to Detect Rare Earth Elements in Three Economic Macroalgaes in China
ZHAO Yan-fang, SHANG De-rong, ZHAI Yu-xiu, NING Jin-song, DING Hai-yan, and SHENG Xiao-feng
In order to investigate the content and distribution of rare earth elements (REE) in main economic macroalgaes in our country, fifteen rare earth elements in three economic macroalgaes (including 30 samples of kelp, 30 samples of laver and 15 samples of Enteromorpha) were detected using ICP-MS method. Results showed thIn order to investigate the content and distribution of rare earth elements (REE) in main economic macroalgaes in our country, fifteen rare earth elements in three economic macroalgaes (including 30 samples of kelp, 30 samples of laver and 15 samples of Enteromorpha) were detected using ICP-MS method. Results showed that the total content of REE in different species of macroalgaes was different. The highest total content of REE was in Enteromorpha (16 012.0 ng·g-1), while in kelp and laver, the total REE was similar for two macroalgaes (3 887.4 and 4 318.1 ng·g-1 respectively). The content of fifteen rare earth elements in kelp ranged from 7.9 to 1 496.4 ng·g-1; in laver, it ranged from 8.2 to 1 836.6 ng·g-1. For Enteromorpha, the concentration of 15 rare earth elements were between 19.2 and 6 014.5 ng·g-1. In addition, the content and distribution of different rare earth elements in different macroalgaes was also different. For kelp, the highest content of REE was Ce (1 496.4 ng·g-1), and the second was La (689.1 ng·g-1). For laver, the highest was Y (1 836.6 ng·g-1), and the second was Ce (682.2 ng·g-1). For Enteromorpha, the highest was Ce (6 014.5 ng·g-1), and the second was La (2 902.9 ng·g-1). Present results also showed that three macroalgaes accumulated the light rare earth elements much more than the high rare earth elements. The light rare earth elements occupied 90.9%, 87.3% and 91.1% for kelp, laver and Enteromorpha respectively. The result that the Enteromorpha had high content of rare earth elements could provide important support for opening new research directions for the utilization of Enteromorpha..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3196 (2015)
Study on Leaching Characteristic of Heavy Metal in the Manure-Amended Soil Using ICP-MASS
ZHAO Ying, MA Qiang, ZHOU Hua, JIANG Chun-ming, XU Yong-gang, JIANG Zi-shao, and YU Wan-tai
Based on an 11-year fertilizer field trial (located at the lower liaohe river plain), the effects of different organic manure application rates on the accumulations of heavy metals (Cu, Zn, Cd and Cr) in surface soil (0～20 cm), and the leaching characteristic and vertical migration pattern of heavy metal have been inveBased on an 11-year fertilizer field trial (located at the lower liaohe river plain), the effects of different organic manure application rates on the accumulations of heavy metals (Cu, Zn, Cd and Cr) in surface soil (0～20 cm), and the leaching characteristic and vertical migration pattern of heavy metal have been investigated in this rainfed agro-ecosystem using undisturbed soil columns. The result showed that the content of heavy metal in surface soil was elevated with the increase of manure application. The increasing magnitude was in the order of Cd>Cu>Zn>Cr. According to the Chinese soil quality standard (GB15618—1995), the application of manure (not exceeding 50 t·ha-1) did not result in serious heavy metal pollution in the surface soil. Chromium met the Grade Ⅰ, and Cu and Zn met the Grade Ⅱ; whereas, Cd was almost exceeded the threshold of Grade Ⅲ. The potential risk of Cd in soil should be paid more attentions in future research. According to the National water quality standard (GB/T14848—93), the Cu and Cd concentrations in leachate samples were up to the Grade Ⅱ except only a few samples that fell in Grade Ⅲ. Furthermore, Cr in the leachate all matched Grade Ⅰ water quality standard. These results indicated long-term application of manure (not exceeding 50 t·ha-1) in our site had not induced contaminant risks of heavy metals in underground water. In addition, the Cu, Zn and Cd (except Cr) in leachate all declined with the increase of soil depth, indicating the low capacity of vertical migration of heavy metal. Among the four heavy metals, Zn and Cr tended to be leached into deep soil, whereas Cu and Cd were more prone to be accumulated in surface soil..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3200 (2015)
Automatic Measurement of the Stellar Atmospheric Parameters Based Mass Estimation
TU Liang-ping, WEI Hui-ming, LUO A-li, and ZHAO Yong-heng
We have collected massive stellar spectral data in recent years, which leads to the research on the automatic measurement of stellar atmospheric physical parameters (effective temperature Teff, surface gravity log g and metallic abundance ［Fe/H］) become an important issue. To study the automatic measurement of these thWe have collected massive stellar spectral data in recent years, which leads to the research on the automatic measurement of stellar atmospheric physical parameters (effective temperature Teff, surface gravity log g and metallic abundance ［Fe/H］) become an important issue. To study the automatic measurement of these three parameters has important significance for some scientific problems, such as the evolution of the universe and so on. But the research of this problem is not very widely, some of the current methods are not able to estimate the values of the stellar atmospheric physical parameters completely and accurately. So in this paper, an automatic method to predict stellar atmospheric parameters based on mass estimation was presented, which can achieve the prediction of stellar effective temperature Teff, surface gravity log g and metallic abundance ［Fe/H］. This method has small amount of computation and fast training speed. The main idea of this method is that firstly it need us to build some mass distributions, secondly the original spectral data was mapped into the mass space and then to predict the stellar parameter with the support vector regression (SVR) in the mass space. we choose the stellar spectral data from the United States SDSS-DR8 for the training and testing. We also compared the predicted results of this method with the SSPP and achieve higher accuracy. The predicted results are more stable and the experimental results show that the method is feasible and can predict the stellar atmospheric physical parameters effectively..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3204 (2015)
Fourier Transform Spectrometer Based on Rotating Parallel-Mirror-Pair
ZHAO Bao-wei, XIANGLI Bin, CAI Qi-sheng, L Qun-bo, and ZHOU Jin-song
In the temporally-modulated Fourier transform spectroscopy, the translational moving mirror is difficult to drive accurately, causing tilt and shear problems. While, a rotational moving mirror can solve these problems. A rotary Fourier transform spectrometer is recommanded in this paper. Its principle is analyzed and tIn the temporally-modulated Fourier transform spectroscopy, the translational moving mirror is difficult to drive accurately, causing tilt and shear problems. While, a rotational moving mirror can solve these problems. A rotary Fourier transform spectrometer is recommanded in this paper. Its principle is analyzed and the optical path difference is deduced. Also, the constrains for engineering realization are presented. This spectrometer consists of one beamsplitter, two fixed mirrors, one rotating parallel mirror pair, a collimating lens, a collecting lens, and one detector. From it’s principle, this spectrometer show a simple structure, and it is assembled and adjustmented easily because the two split light are interfered with each other after reflected through the same plane mirror; By calculating the expression of it’s optical path difference, the spectrometer is easy to realize large optical path difference, meaning high spectral resolution; Through analyzing it’s engineering design constraints and computer simulation, it is known that the spectrometer should get the high resolution sample by high-speed spinning motor, so it is easy to achieve precise motion control, good stability, fast measurement speed..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3209 (2015)
Optical Path Difference Analysis and Simulation of Four Typical Rotary Type Interferometer
FENG Ming-chun, LIU Wen-qing, XU Liang*, GAO Min-guang, WEI Xiu-li, TONG Jing-jing, and LI Xiang-xian
The four kinds of the structure characteristics of rotary type interferometer are mainly analyzed from the classical Michelson interferometer structure in the paper. The Optical path difference between the interferometer and the rotation angle is also analyzed. By setting parameters, the four kinds of rotary type opticThe four kinds of the structure characteristics of rotary type interferometer are mainly analyzed from the classical Michelson interferometer structure in the paper. The Optical path difference between the interferometer and the rotation angle is also analyzed. By setting parameters, the four kinds of rotary type optical path difference of the interferometer are simulated based on the optical path difference formula. The rotation velcocity of the four kinds of interferometers is also simulated. By simulation and contrast of the optical path difference, the relationship is intuitively reflect by figure between the optical path difference and the rotation angle. The scope of the rotation angle is discussed within 3% of the velocity errors. It is the very good reference significance to study the structure and properties of the interferometer by analyzing and simulating the optical path difference discussed in the paper..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3214 (2015)
Dynamic Wavelength Characteristics of Semiconductor Laser in Electric Current Tuning Process
LIU Jing-wang, LI Zhong-yang, ZHANG Wei-zhong, WANG Qing-chuan, AN Ying, and LI Yong-hui
In order to measure the dynamic wavelength of semiconductor lasers under current tuning, an improved method of fiber delay self-heterodyne interferometer was proposed. The measurement principle, as well the beat frequency and dynamic wavelength of recursive relations are theoretically analyzed. The application of the eIn order to measure the dynamic wavelength of semiconductor lasers under current tuning, an improved method of fiber delay self-heterodyne interferometer was proposed. The measurement principle, as well the beat frequency and dynamic wavelength of recursive relations are theoretically analyzed. The application of the experimental system measured the dynamic wavelength characteristics of distributed feedback semiconductor laser and the static wavelength characteristics measurement by the spectrometer. The comparison between the two values indicates that both dynamic and static wavelength characteristic with the current tuning are the similar non-linear curve. In 20~100 mA current tuning range, the difference of them is less than 0.002 nm. At the same time, according to the absorption lines of CO2 gas, and HITRAN spectrum library, we can identify the dynamic wavelength of the laser. Comparing it with dynamic wavelength calculated by the beat signal, the difference is only 0.001 nm, which verifies the reliability of the experimental system to measure the dynamic wavelength..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3220 (2015)
A New Method for Eliminating Background Signal Drift to Improve the Detection Precision in Continuous Harmonic Detection
ZHAO Ying, ZHAO Xue-hong, WANG Zhe, ZHANG Rui, and WANG Yan
To overcome the second harmonic background signal drift in gas continuous detection based on tunable diode laser absorption spectroscopy(TDLAS), a new method of background elimination was proposed by changing center current of the laser. This method can eliminated the effects of background signal drifting on concentratTo overcome the second harmonic background signal drift in gas continuous detection based on tunable diode laser absorption spectroscopy(TDLAS), a new method of background elimination was proposed by changing center current of the laser. This method can eliminated the effects of background signal drifting on concentration inversion. Based on the wavelength modulation theory, the theoretical expression of the second harmonic of the background signal is derived. In addition, the second harmonic background signal components and the factors that affect it are described. In different working temperatures, the relationship curve between thelaser current and output light intensity. In the process of continuous detection, we analyzes the feasibility ofchangingthe laser center current extraction of background signal. Combined with the principle of the background signal searching, the LabView flow chart was designed to search background center current. Ammonia(NH3) was detected by the TDLAS experimental system, which demonstrated the feasibility of the new method. The range of experiment parameters and the range of background center current searches were determined, in the situation that there was only one absorption line in the full laser workspace. The experimental results showed that this method realizes background signal extraction, reduces the error of concentration inversion and the effects of concentration inversion bybackground signal. Thus it improved the detection accuracy of the concentration. In the continuous detection experiment, the standarddeviation of inversion concentration reduced from 2.688 3 to 1.856 1, which demonstrated that the degree of dispersion of detected concentration is reduced, even eliminate the effects of background signal drifting on concentration inversion and the accuracy of detection is improved. This method provides an effective background drifting elimination approach for improving the detection accuracy of the concentration..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3224 (2015)
The Study of Characteristics of Cladding-Reduced Coated Long-Period Fiber Grating Based on Mode Transition and Dual Peak Resonance
LAN Jin-long, and GU Zheng-tian
Based on coupled-mode theory, the mode transition of the high-order cladding modes in a coated long-period fiber grating (LPFG) has been studied firstly; the mode transition region and non-mode transition region of high-order cladding modes are divided. The response characteristic of cladding mode effective index with Based on coupled-mode theory, the mode transition of the high-order cladding modes in a coated long-period fiber grating (LPFG) has been studied firstly; the mode transition region and non-mode transition region of high-order cladding modes are divided. The response characteristic of cladding mode effective index with increasing the overlay thickness is analyzed; the shift of resonant wavelength in the mode transition region will be larger than that in the non-mode transition region. Further, the changes of the resonant wavelength of some high-order cladding modes with grating period are investigated when the cladding radius are different, the shift between two resonant wavelengths of dual peak in the mode transition region is bigger than that in non-mode transition region when the cladding radius are uniform. And the shift between two resonant wavelengths of dual peak will be increased by the decrease of the cladding radius in both mode transition and non-mode transition regions. Finally, the response characteristics of film refractive index of coated LPFG are investigated for a high-order cladding mode while the cladding radius are different and the overlay thickness is located in mode transition region and non-transition mode region, then the optimized design scheme is come up with. The higher sensitivity dual-peak sensor of coated LPFG than the traditional dual-peak sensor will be obtained when the overlay thickness and refractive index is located in the mode transition region and the grating period close to the phase matching turning points. Further, the resolution power of coated LPFG sensor will further be improved by the appropriate reducing of the cladding radius..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3230 (2015)
A Quantum Dot Fluorescence Sensor System Design for Hg2+ Trace Detection
LUO Wei, ZENG Xin-hua, LI Miao, ZHENG Shou-guo, LI Hua-long, WENG Shi-zhuang, and WANG Shao-qi
The detection of Hg2+ ions usually requires large laboratory equipment, which encounters difficulties for rapid field test in most applications. In this paper, we design a reflective sensor for trace Hg2+ analysis based on the fluorescent quenching of Quantum dots, which contains two major modules, i.e. the fluorescentThe detection of Hg2+ ions usually requires large laboratory equipment, which encounters difficulties for rapid field test in most applications. In this paper, we design a reflective sensor for trace Hg2+ analysis based on the fluorescent quenching of Quantum dots, which contains two major modules, i.e. the fluorescent sensing module and the signal processing module. The fluorescence sensing module is composed of a laser source, a light collimated system and a photo-detector, which enables the realization of the fluorescence excitation as well as its detection. The signal processing module realized the further amplification of the detected signal and hereafter the filtering of noises. Furthermore, the Hg2+ concentration will displayed on the QT interface using a Linux embedded system. The sensor system is low cost and small, which makes it available for rapid field test or portable applications. Experimental results show that the sensor has a good linear relationship for the Hg2+ concentration range from 15.0×10-9 to 1.8×10-6 mol·L-1. The regression equation is V0/V=1.309 13+3.37ｃ, where c is Hg2+ concentration, and V0 is the voltage value for the blank case. In our work, the linearity is determined as 0.989 26. The experiments exhibit that Ca2+, Mn2+ and Pb2+ ions have small influence on the Hg2+ detection, and the interfere of other common ions can be neglected, which indicates a good selectivity of the sensor. Finally, it shows that our sensor has a rapid response time of 35 s and a good repeatability, thus it is potential for field test of trace Hg2+..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3236 (2015)
Photoluminescence of Sinthetic Scapolite Na4Ca4Al6Si9O24 Phosphors Activated with Ce3+ and Tb3+ and Energy Transfer from Ce3+ to Tb3+
MA Yuan-yuan, HE Jiu-yang, Aziguli·Reheman, Bahadeer·Rouzi, and Aierken·Sidike
Natural scapolite including the S-2 impurity is a typical silicate luminescent mineral. According to the formation conditions and chemical composition of natural scapolite, we synthesized Na4Ca4Al6Si9O24(scapolite) by the high temperature solid-phase reaction, and prepared the synthetic scapolite phosphors activated wiNatural scapolite including the S-2 impurity is a typical silicate luminescent mineral. According to the formation conditions and chemical composition of natural scapolite, we synthesized Na4Ca4Al6Si9O24(scapolite) by the high temperature solid-phase reaction, and prepared the synthetic scapolite phosphors activated with Ce3+ and Tb3+. The photoluminescence (PL) properties of the obtained phosphors were studied. The results indicated that the PL intensity of green (545 nm) emission corresponding to the 5D4 →7F5 transition within Tb3+in the Ce3+, Tb3+-codoped samples was much higher than that of the Tb3+-doped samples. The PL properties of the samples activated with various Ce3+ concentrations were measured, and their fluorescence lifetime and energy transfer mechanism were analyzed. We proved that there was energy transfer from Ce3+ to Tb3+, and the energy transfer efficiency was at its maximum when the Ce3+ to Tb3+ mass ratio was 0.02∶0.03. Upon measurement by chromaticity coordinates, we found that the luminescence of the samples could be adjusted in the green area with varying Ce3+ concentrations. We thus deem that scapolite phosphors Na4Ca4Al6Si9O24∶Ce3+, Tb3+ are promising to become the new white LED phosphors..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3241 (2015)
High-Frequency Observation of Water Spectrum and Its Application in Monitoring of Dynamic Variation of Suspended Materials in the Hangzhou Bay
DAI Qian, PAN De-lu, HE Xian-qiang, ZHU Qian-kun, GONG Fang, and HUANG Hai-qing
In situ measurement of water spectrum is the basis of the validation of the ocean color remote sensing. The traditional method to obtain the water spectrum is based on the shipboard measurement at limited stations, which is difficult to meet the requirement of validation of ocean color remote sensing in the highly dynaIn situ measurement of water spectrum is the basis of the validation of the ocean color remote sensing. The traditional method to obtain the water spectrum is based on the shipboard measurement at limited stations, which is difficult to meet the requirement of validation of ocean color remote sensing in the highly dynamic coastal waters. To overcome this shortage, continuously observing systems of water spectrum have been developed in the world. However, so far, there are still few high-frequency observation systems of the water spectrum in coastal waters, especially in the highly turbid and high-dynamic waters. Here, we established a high-frequency water-spectrum observing system based on tower in the Hangzhou Bay. The system measures the water spectrum at a step of 3 minutes, which can fully match the satellite observation. In this paper, we primarily developed a data processing method for the tower-based high-frequency water spectrum data, to realize automatic judgment of clear sky, sun glint, platform shadow, and weak illumination, etc., and verified the processing results. The results show that the normalized water-leaving radiance spectra obtained through tower observation have relatively high consistency with the shipboard measurement results, with correlation coefficient of more than 0.99, and average relative error of 9.96%. In addition, the long-term observation capability of the tower-based high-frequency water-spectrum observing system was evaluated, and the results show that although the system has run for one year, the normalized water-leaving radiance obtained by this system have good consistency with the synchronously measurement by Portable spectrometer ASD in respect of spectral shape and value, with correlation coefficient of more than 0.90 and average relative error of 6.48%. Moreover, the water spectra from high-frequency observation by the system can be used to effectively monitor the rapid dynamic variation in concentration of suspended materials with tide. The tower-based high-frequency water-spectrum observing system provided rich in situ spectral data for the validation of ocean color remote sensing in turbid waters, especially for validation of the high temporal-resolution geostationary satellite ocean color remote sensing..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3247 (2015)
The Extraction Model of Paddy Rice Information Based on GF-1 Satellite WFV Images
YANG Yan-jun, HUANG Yan, TIAN Qing-jiu, WANG Lei, GENG Jun, and YANG Ran-ran
In the present, using the characteristics of paddy rice at different phenophase to identify it by remote sensing images is an efficient way in the information extraction. According to the remarkably properties of paddy rice different from other vegetation, which the surface of paddy fields is with a large number of watIn the present, using the characteristics of paddy rice at different phenophase to identify it by remote sensing images is an efficient way in the information extraction. According to the remarkably properties of paddy rice different from other vegetation, which the surface of paddy fields is with a large number of water in the early stage, NDWI (normalized difference water index) which is used to extract water information can reasonably be applied in the extraction of paddy rice at the early stage of the growth. And using NDWI ratio of two phenophase can expand the difference between paddy rice and other surface features, which is an important part for the extraction of paddy rice with high accuracy. Then using the variation of NDVI (normalized differential vegetation index) in different phenophase can further enhance accuracy of paddy rice information extraction. This study finds that making full advantage of the particularity of paddy rice in different phenophase and combining two indices (NDWI and NDVI) associated with paddy rice can establish a reasonable, accurate and effective extraction model of paddy rice. This is also the main way to improve the accuracy of paddy rice extraction.The present paper takes Lai’an in Anhui Province as the research area, and rice as the research object. It constructs the extraction model of paddy rice information using NDVI and NDWI between tillering stage and heading stage. Then the model was applied to GF1-WFV remote sensing image on July 12, 2013 and August 30, 2013.And it effectively extracted out of paddy rice distribution in Lai’an and carried on the mapping. At last, the result of extraction was verified and evaluated combined with field investigation data in the study area. The result shows that using the extraction model can quickly and accurately obtain the distribution of rice information, and it has the very good universality..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3255 (2015)
Degradation Ability of Modified Polyvinyl Alcohol Film for Coating of Fertilizer
ZOU Hong-tao, LING Yao, YU Yang, ZHANG Yu-ling, YU Na, and ZHANG Yu-long
Using outdoor exposure and cinnamon soil incubation test, by quality changes, infrared spectroscopy and electron microscopic scanning technology, to research the degradation ability of self-developed coated fertilizer films. The results of outdoor exposure and cinnamon soil incubation test showed that all films had cerUsing outdoor exposure and cinnamon soil incubation test, by quality changes, infrared spectroscopy and electron microscopic scanning technology, to research the degradation ability of self-developed coated fertilizer films. The results of outdoor exposure and cinnamon soil incubation test showed that all films had certain degradation ability, and the degradation rate increased with the increase of time. Under two kinds of test conditions, the highest degradation rate could reach above 35%. The degradation ability of film citric acid/PVA was much stronger than epoxy resin/PVA. The degradation ability of citric acid/PVA/diatomite composite film materials was further enhanced because of the addition of diatomite. The epoxy resin/PVA composite film materials, although they had certain degradability, compared to the contrast, the difference was not significant, and adding diatomite can’t obviously increase the degradation rate. The results of IR spectroscopy showed that some major functional groups, such as CO, CC, CH would be reduced after degradation, and the transmission rate also increased, which showed that the degradation of composite film materials must be happened. Scanning electron microscopy showed that the surface becomes rough and uneven, and it also meant the films have some degradation. The results of IR spectroscopy and scanning electron microscopy were consistent with the results of quality change test, and could more objectively represent the degradability of film material. Modified film materials can effectively control nutrient release without causing harm to the soil environment, so it is suitable for the film materials of coated fertilizer..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3262 (2015)
Discrimination of Maize Haploid Seeds from Hybrid Seeds Using Vis Spectroscopy and Support Vector Machine Method
LIU Jin, GUO Ting-ting, LI Hao-chuan, JIA Shi-qiang, YAN Yan-lu, AN Dong, ZHANG Yao, and CHEN Shao-jiang
Doubled haploid (DH) lines are routinely applied in the hybrid maize breeding programs of many institutes and companies for their advantages of complete homozygosity and short breeding cycle length. A key issue in this approach is an efficient screening system to identify haploid kernels from the hybrid kernels crossedDoubled haploid (DH) lines are routinely applied in the hybrid maize breeding programs of many institutes and companies for their advantages of complete homozygosity and short breeding cycle length. A key issue in this approach is an efficient screening system to identify haploid kernels from the hybrid kernels crossed with the inducer. At present, haploid kernel selection is carried out manually using the“red-crown” kernel trait (the haploid kernel has a non-pigmented embryo and pigmented endosperm) controlled by the R1-nj gene. Manual selection is time-consuming and unreliable. Furthermore, the color of the kernel embryo is concealed by the pericarp. Here, we establish a novel approach for identifying maize haploid kernels based on visible (Vis) spectroscopy and support vector machine (SVM) pattern recognition technology. The diffuse transmittance spectra of individual kernels (141 haploid kernels and 141 hybrid kernels from 9 genotypes) were collected using a portable UV-Vis spectrometer and integrating sphere. The raw spectral data were preprocessed using smoothing and vector normalization methods. The desired feature wavelengths were selected based on the results of the Kolmogorov-Smirnov test. The wavelengths with p values above 0.05 were eliminated because the distributions of absorbance data in these wavelengths show no significant difference between haploid and hybrid kernels. Principal component analysis was then performed to reduce the number of variables. The SVM model was evaluated by 9-fold cross-validation. In each round, samples of one genotype were used as the testing set, while those of other genotypes were used as the training set. The mean rate of correct discrimination was 92.06%. This result demonstrates the feasibility of using Vis spectroscopy to identify haploid maize kernels. The method would help develop a rapid and accurate automated screening-system for haploid kernels..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3268 (2015)
Determination of Beryllium in Soil and Sediment by Graphite Furnace Atomic Absorption with a Microwave-Acid Digestion Method
LIN Hai-lan, GAN Jie, YU Lei, ZHU Ri-long, TIAN Yun, and LUO Yue-ping
A method for determination of beryllium in soils and sediments by microwave-acid digestion/graphite furnace atomic absorption (GFAA) is described. In this paper, the working conditions of the instrument are optimized, the drawing of calibration curve is expounded, the pretreatment process of soil and sediments (includiA method for determination of beryllium in soils and sediments by microwave-acid digestion/graphite furnace atomic absorption (GFAA) is described. In this paper, the working conditions of the instrument are optimized, the drawing of calibration curve is expounded, the pretreatment process of soil and sediments (including microwave heating process and the selection of digestion system) is discussed, and the interference of coexisting elements is examined. The sample was pretreated by microwave digestion parameters using HNO3/HCl/HF mixed acid system. The method is fast and simple without matrix modifier, and has no interference by coexisting ions, and has high repeatability and reproducibility. Under the optimal experimental conditions, the limit of detection (LOD) is 0.004 9 mg·kg-1 (sample quantity 0.200 0 g, sample volume 25 mL), and the limits of quantitation (LOQ) is 0.020 mg·kg-1. This method is used to measure the standard samples and actual samples, whether in the laboratory, or between laboratories, has good accuracy and precision..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 3275 (2015)
[in Chinese]
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 11, 1 (2015)
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