Journals >Spectroscopy and Spectral Analysis
Contents
2015
Volume: 35 Issue 2
57 Article(s)
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Research Article
Research on Symmetrical Optical Waveguide Based Surface Plasmon Resonance Sensing with Spectral Interrogation
ZHANG Yi-long, LIU Le, GUO Jun, ZHANG Peng-fei, GUO Ji-hua, MA Hui, and HE Yong-hong
Surface plasmon resonance (SPR) sensors with spectral interrogation can adopt fiber to transmit light signals, thus leaving the sensing part separated, which is very convenient for miniaturization, remote-sensing and on-site analysis. Symmetrical optical waveguide (SOW) SPR has the same refractive index of the two buffSurface plasmon resonance (SPR) sensors with spectral interrogation can adopt fiber to transmit light signals, thus leaving the sensing part separated, which is very convenient for miniaturization, remote-sensing and on-site analysis. Symmetrical optical waveguide (SOW) SPR has the same refractive index of the two buffer media layers adjacent to the metal film, resulting in longer propagation distance, deeper penetration depth and better performance compared to conventional SPR. In the present paper, we developed a symmetrical optical waveguide (SOW) SPR sensor with wavelength interrogation. In the system, MgF2-Au-MgF2 film was used as SOW module for glucose sensing, and a fiber based light source and detection was used in the spectral interrogation. In the experiment, a refractive index resolution of 2.8×10－7 RIU in fluid protocol was acquired. This technique provides advantages of high resolution and could have potential use in compact design, on-site analysis and remote sensing..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 289 (2015)
Strong and Tunable Field Enhancement Obtained by Periodic Rectangular Pit Structure
WANG Meng, WANG Bin, FU Su-yang, SUN Xi-peng, HUANG Sen-peng, GUO Ting-ke, LI Hao-yu, XU Xiao-xuan, and WANG Yu-fang
The authors have designed a novel type of periodic rectangular pit nanostructure substrate based on the surface plasmon principle. Finite element method was employed to simulate the optical near-field distribution. Strongly enhanced field whose electric intensity Emax/E0 can be as high as 20 at resonance frequency appeThe authors have designed a novel type of periodic rectangular pit nanostructure substrate based on the surface plasmon principle. Finite element method was employed to simulate the optical near-field distribution. Strongly enhanced field whose electric intensity Emax/E0 can be as high as 20 at resonance frequency appears around pithead of the periodic structure. As the period of structure, pit length l, width w and environment change, the authors observe the regular shifting of plasmon resonant wavelength which can cover the range from 500 to 1 000 nm. The red shifts of SPR resonance peaks are increased with the increment of period Px when incident light is polarized along x axis. An abrupt decrease in localized electric field in the pit is observed as incident wavelength approaches Px. This is due to the satisfaction of wave vector matching condition and the excitation of propagating SPP. SPR resonance peaks also red shifts with the increment on pit length l and environment dielectric refractive index, presenting a linear dependence with pit length l. While the resonance peaks are blue shifted with the increment of pit width w. The results presented in this paper will provide a way to tune the plasmon resonant wavelength. Inspired by Jain’s report, SPR resonance peaks’ shifting with the changing of structure parameters can be explained by viewing the rectangular pit nanostructure as combination of two pairs of dipole-dipole coupling models along x and y axis respectively..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 293 (2015)
Research on Ground Scenery Spectral Radiation Source with Tunable Spectra
XIANG Jin-rong, REN Jian-wei, LI Bao-yong, WAN Zhi, LIU Ze-xun, LIU Hong-xing, LI Xian-sheng, and SUN Jing-xu
A spectrum-tunable ground scenery spectrum radiation source, using LEDs and bromine tungsten lamp as luminescence media, was introduced. System structure and control of the spectrum radiation source was expounded in detail. In order to simulate various ground scenery spectrum distribution with different shapes, a grounA spectrum-tunable ground scenery spectrum radiation source, using LEDs and bromine tungsten lamp as luminescence media, was introduced. System structure and control of the spectrum radiation source was expounded in detail. In order to simulate various ground scenery spectrum distribution with different shapes, a ground scenery spectral database was established in the control system. An improved genetic algorithm was proposed, and a large number of ground scenery spectra were produced by the simulator. Spectral similarity and the average spectral matching error of several typical ground scenery spectra were further analyzed. Spectral similarity of red bands, green bands, blue bands and near-infrared spectral band also was discussed. When the radiance of the target was 50 W·(m2·sr)-1, the average spectral matching error was less than 10% and spectral similarity was greater than 0.9, up to 0.983. Spectral similarity of red band, green band, blue band and near-infrared band (especially green band and near-infrared band) was less than that of full-band.Compared with blue band and red band, spectral similarity of green band and near-infrared band low-amplitude maximum can rearch50%. Ground scenery spectrum radiation source can be used as radiometric calibration source for optical remote sensor, and calibration error, which is caused by objectives and calibration sources spectral mismatch, can be effectively reduced..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 298 (2015)
The Auto-Focusing Remote Laser-Induced Breakdown Spectroscopy System
HAN Zhen-yu, PAN Cong-yuan, AN Ning, DU Xue-wei, YU Yun-si, DU Liang-liang, WANG Sheng-bo, and WANG Qiu-ping
The present paper presents an auto-focus laser-induced breakdown spectroscopy (LIBS) remote measuring system. This system contains a Schwarzschild telescope, which consists of a convex mirror and a concave mirror. The two spherical mirrors are coaxially placed. The convex mirror is mounted on a motorized linear translaThe present paper presents an auto-focus laser-induced breakdown spectroscopy (LIBS) remote measuring system. This system contains a Schwarzschild telescope, which consists of a convex mirror and a concave mirror. The two spherical mirrors are coaxially placed. The convex mirror is mounted on a motorized linear translation stage. With this motorized linear translation stage, the convex mirror can move along the optical axis to change the spacing between the convex mirror and the concave mirror. Therefore the focal length can be adjusted to focus the laser on samples at different distances and collect the plasma spectra. The advantages of the telescope system include, firstly, the light path of laser focusing and spectra signal collection is the same, which make it easier for mounting and collimation;secondly, the light path of the telescope uses total reflection type, which is fit for the detection in ultra-violate region;finally, the telescope consists of only two spherical mirrors which are relatively easier to manufacture. Within the translation range of the motorized linear translation stage, the focal length of the telescope in this paper can be adjusted from 1.5 to 3.6 m. The diameter of the focusing spot varies from 0.5 to 1.0 mm. Utilizing this telescope system, LIBS experiments were conducted using copper sample. And the characteristic lines of Cu element (Cu Ⅰ 223.01 nm, Cu Ⅰ 224.43 nm) obtained are used for the auto focusing. By investigating the relation of the area of spectral lines covered and the spacing between the mirrors, the optimal laser focusing location was obtained .The LIBS experiment results show that the system functions well, fulfilling the demand of remote ablation of sample and LIBS spectral measuring, and the telescope is able to auto-focus the laser on samples at different position to perform remote LIBS experiment..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 304 (2015)
The Research on Separating and Extracting Overlapping Spectral Feature Lines in LIBS Using Damped Least Squares Method
WANG Yin, ZHAO Nan-jing, LIU Wen-qing, YU Yang, FANG Li, MENG De-shuo, HU Li, ZHANG Da-hai, MA Ming-jun, XIAO Xue, WANG Yu, and LIU Jian-guo
In recent years, the technology of laser induced breakdown spectroscopy has been developed rapidly. As one kind of new material composition detection technology, laser induced breakdown spectroscopy can simultaneously detect multi elements fast and simply without any complex sample preparation and realize field, in-sitIn recent years, the technology of laser induced breakdown spectroscopy has been developed rapidly. As one kind of new material composition detection technology, laser induced breakdown spectroscopy can simultaneously detect multi elements fast and simply without any complex sample preparation and realize field, in-situ material composition detection of the sample to be tested. This kind of technology is very promising in many fields. It is very important to separate, fit and extract spectral feature lines in laser induced breakdown spectroscopy, which is the cornerstone of spectral feature recognition and subsequent elements concentrations inversion research. In order to realize effective separation, fitting and extraction of spectral feature lines in laser induced breakdown spectroscopy, the original parameters for spectral lines fitting before iteration were analyzed and determined. The spectral feature line of chromium (CrⅠ: 427.480 nm) in fly ash gathered from a coal-fired power station, which was overlapped with another line(FeⅠ: 427.176 nm), was separated from the other one and extracted by using damped least squares method. Based on Gauss-Newton iteration, damped least squares method adds damping factor to step and adjust step length dynamically according to the feedback information after each iteration, in order to prevent the iteration from diverging and make sure that the iteration could converge fast. Damped least squares method helps to obtain better results of separating, fitting and extracting spectral feature lines and give more accurate intensity values of these spectral feature lines. The spectral feature lines of chromium in samples which contain different concentrations of chromium were separated and extracted. And then, the intensity values of corresponding spectral lines were given by using damped least squares method and least squares method separately. The calibration curves were plotted, which showed the relationship between spectral line intensity values and chromium concentrations in different samples. And then their respective linear correlations were compared. The experimental results showed that the linear correlation of the intensity values of spectral feature lines and the concentrations of chromium in different samples, which was obtained by damped least squares method, was better than that one obtained by least squares method. And therefore, damped least squares method was stable, reliable and suitable for separating, fitting and extracting spectral feature lines in laser induced breakdown spectroscopy..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 309 (2015)
Near-Infrared Quantum Cutting Downconversion Luminescence of Yb3+ Ion Cooperative Energy Transferred from YVO4 Matrix Donor
CHEN Xiao-bo, ZHOU Gu, ZHOU Yong-fen, WU Zheng-long, GUO Yu-ying, WANG Shui-feng, ZOU Qiu-yan, ZHUANG Jian, CHEN Xiao-duan, LI Chun-mi, YAO Wen-ting, and CHENG Huan-li
The present manuscript researches the near infrared quantum cutting luminescence phenomena of Yb3+ ion in YVO4 crystal matrix. The luminescence spectra, excitation spectra and fluorescence lifetimes were measured. It was found that the excitation of YVO4 crystal matrix energy band by 322.0 nm light can result in the efThe present manuscript researches the near infrared quantum cutting luminescence phenomena of Yb3+ ion in YVO4 crystal matrix. The luminescence spectra, excitation spectra and fluorescence lifetimes were measured. It was found that the excitation of YVO4 crystal matrix energy band by 322.0 nm light can result in the effective secondary cooperative energy transfer of Yb3+ ion from the YVO4 crystal matrix. It results in the intense 985.5 nm 2F5/2→2F7/2 near infrared quantum cutting luminescence of Yb3+ ion. Meanwhile, the 430.0 nm luminescence intensity of YVO4 crystal matrix decreases greatly. From the experimental measurements, it was found that the lifetime of 430.0 nm fluorescence of (A) Yb(1.5)∶YVO4 crystal is τA=3.785 s and that of (B) YVO4 crystal is τB=22.72 s. It was found also that the theoretical efficiency up limit of quantum cutting of (A) Yb(1.5)∶YVO4 crystal is aboutη1.5%Yb=183.3%..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 315 (2015)
The Impact of ZnS/CdS Composite Window Layer on the Quantun Efficiency of CdTe Solar Cell in Short Wavelength
ZHANG Li-xiang, FENG Liang-huan, WANG Wen-wu*, XU Hang, WU Li-li, ZHANG Jing-quan, LI Wei, and ZENG Guang-gen
ZnS/CdS composite window layer was prepared by magnetron sputtering method and then applied to CdTe solar cell. The morphology and structure of films were measured. The data of Ⅰ-Ⅴ in light and the quantum efficiency of CdTe solar cells with different window layers were also measured. The effect of ZnS films prepared iZnS/CdS composite window layer was prepared by magnetron sputtering method and then applied to CdTe solar cell. The morphology and structure of films were measured. The data of Ⅰ-Ⅴ in light and the quantum efficiency of CdTe solar cells with different window layers were also measured. The effect of ZnS films prepared in different conditions on the performance of CdTe solar cells was researched. The effects of both CdS thickness and ZnS/CdS composite layer on the transmission in short wavelength were studied. Particularly, the quantum efficiency of CdTe solar cells with ZnS/CdS window layer was measured. The results show as follows. With the thickness of CdS window layer reducing from 100 to 50 nm, the transmission increase 18.3% averagely in short wavelength and the quantum efficiency of CdTe solar cells increase 27.6% averagely. The grain size of ZnS prepared in 250 ℃ is smaller than prepared at room temperature. The performance of CdTe solar cells with ZnS/CdS window layer is much better if ZnS deposited at 250 ℃. This indicates grain size has some effect on the electron transportation. When the CdS holds the same thickness, the transmission of ZnS/CdS window layer was improved about 2% in short wavelength compared with CdS window layer. The quantum efficiency of CdTe solar cells with ZnS/CdS window layer was also improved about 2% in short wavelength compared with that based on CdS window layer. These indicate ZnS/CdS composite window layer can increase the photon transmission in short wavelength so that more photons can be absorbed by the absorbent layer of CdTe solar cells..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 320 (2015)
Three Photons Quantum-Cutting System on the Rear Surface of Cells to Improve the Efficiencies of Solar Cells
YAO Wen-ting, CHEN Xiao-bo, CHENG Huan-li, ZHOU Gu, DENG Zhi-wei, LI Yong-liang, YAN Da-dong, and PENG Fang-lin
The authors present a solar cell model with a three photons quantum-cutting system on the rear surface, then the method of calculation of limiting efficiencies was used to get the maximum efficiency 58.58% at the band gap Eg=0.931 5 eV, and in contrast with two-photons quantum-cutting system, it is greatly improved. ThThe authors present a solar cell model with a three photons quantum-cutting system on the rear surface, then the method of calculation of limiting efficiencies was used to get the maximum efficiency 58.58% at the band gap Eg=0.931 5 eV, and in contrast with two-photons quantum-cutting system, it is greatly improved. The result can prove that the three-photons quantum-cutting has a great sense to improve the efficiencies of solar cells. It is the exciting development for us to find out the useful luminescence materials to get the high efficiency..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 325 (2015)
Er3+∶Yb3+ Co-Doped Nanocrystals BaGd2ZnO5 of Up-Conversion Optical Temperature Sensing
LIU Yan-zhou, YANG Yan-min, GUO Yan-ming, ZHANG Lian-shui, MI Chao, and LIU Lin-lin
By far, the most efficient up-conversion nanocrystals luminescence materials BaGd2ZnO5∶4%Yb3+,1%Er3+, with stable chemical performance, were prepared by using Sol-gel method. XRD pattern shows that the sample is pure phase, belongs to the orthogonal crystals, and space group is Pbnm;SEM micrograph shows that the preparBy far, the most efficient up-conversion nanocrystals luminescence materials BaGd2ZnO5∶4%Yb3+,1%Er3+, with stable chemical performance, were prepared by using Sol-gel method. XRD pattern shows that the sample is pure phase, belongs to the orthogonal crystals, and space group is Pbnm;SEM micrograph shows that the prepared sample of the morphology sized around 150 nm is evenly distributed. Samples with 971 nm semiconductor laser excitation produce a strong green emission, visible to the naked eye, and up-conversion strength and pump energy relation n=1.22 is two-photon for the realization of the up-conversion emission. They originated from Er3+ ions 2H11/2→4I15/2 and 4S3/2→4I15/2 transition emission, Er3+ ions main excited state absorption (ESA) process is: 4I15/2→4I11/2→2F7/2→2H11/2, 4S3/2, Yb3+ was added because of its large absorption cross section (104 cm-1) so that it is easy to transfer excitation energy to the Er3+ ions which enhance the layout particles number and the energy state of the 2F7/2, thereby enhancing the intensity of the peaks of the spectrum. Fluorescence intensity ratio (FIR) technique based on the green up-conversion emission of the sample has been studied because the Er3+ ions 2H11/2 and 4S3/2 energy level spacing is small. The electrons at the two levels conform to the Boltzmann distribution which is a function of temperature, and thus the fluorescence intensity ratio of two levels can be used to measure the temperature of the substrate material. This method does not interfere with temperature field of the measured object, and can eliminate the uncertainty of the accuracy;the test has a wide temperature range and reasonable temperature resolution, the pump source used is simple, convenient and inexpensive, and has more commercial values. The temperature range of the samples is from 350 to 800 K, and the highest temperature measuring sensitivity can reach 0.003 1 K-1. At the same time, under low excitation density, it can produce higher conversion transmission power, making it become ideal material for distance non-contact temperature measurement..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 329 (2015)
Synthesis and Spectroscopy of Silica Nanoparticles as Scatter Centers in Random Gain Porous Media
Firas J. Kadhim, Baha T. Chiad, Nathera A. Ali, and Jafer F. Odah
This work was carried out to synthesis a silica matrix by sol-gel technique, which used as host to Kiton Red laser dye doped with silica nanoparticles, which also prepared by sol-gel technique, to obtain KR-SiO2 nanoparticles confined in silica xerogel matrix. The rods at different pH values were successfully synthesizThis work was carried out to synthesis a silica matrix by sol-gel technique, which used as host to Kiton Red laser dye doped with silica nanoparticles, which also prepared by sol-gel technique, to obtain KR-SiO2 nanoparticles confined in silica xerogel matrix. The rods at different pH values were successfully synthesized. The different values of pH cause different size of obtained nanoparticles, these nanoparticles act as scatter centers in the matrix. Amplified spontaneous emission (ASE), threshold pumping energy (Eth), and mean free path (lt) for photons in the rods have been reported. the results show that the values of bandwidth at full width half-maximum (FWHM) and the threshold energy are about 8.7 nm and 12 mJ respectively..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 334 (2015)
Determination of Minimum Enzymatic Decolorization Time of Reactive Dye Solution by Spectroscopic & Mathematical Approach
Mithat Celebi, Zafer Omer Ozdemir, Emre Eroglu, Melda Altikatoglu, and Ibrahim Guney
Synthetic dyes are very important for textile dyeing, paper printing, color photography and petroleum products. Traditional methods of dye removal include biodegradation, precipitation, adsorption, chemical degradation, photo degradation, and chemical coagulation. Dye decolorization with enzymatic reaction is an importSynthetic dyes are very important for textile dyeing, paper printing, color photography and petroleum products. Traditional methods of dye removal include biodegradation, precipitation, adsorption, chemical degradation, photo degradation, and chemical coagulation. Dye decolorization with enzymatic reaction is an important issue for several research field (chemistry, environment) In this study, minimum decolorization time of Remazol Brilliant Blue R dye with Horseradish peroxidase enzyme was calculated using with mathematical equation depending on experimental data. Dye decolorization was determined by monitoring the absorbance decrease at the specific maximum wavelength for dye. All experiments were carried out with different initial dye concentrations of Remazol Brilliant Blue R at 25 ℃ constant temperature for 30 minutes. The development of the least squares estimators for a nonlinear model brings about complications not encountered in the case of the linear model. Decolorization times for completely removal of dye were calculated according to equation. It was shown that mathematical equation was conformed exponential curve for dye degradation..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 340 (2015)
Advances of NIR Spectroscopy Technology Applied in Seed Quality Detection
ZHU Li-wei, MA Wen-guang, HU Jin, ZHENG Yun-ye, TIAN Yi-xin, GUAN Ya-jing, and HU Wei-min
Near infrared spectroscopy (NIRS) technology developed fast in recent years, due to its rapid speed, less pollution, high-efficiency and other advantages. It has been widely used in many fields such as food, chemical industry, pharmacy, agriculture and so on. The seed is the most basic and important agricultural capitaNear infrared spectroscopy (NIRS) technology developed fast in recent years, due to its rapid speed, less pollution, high-efficiency and other advantages. It has been widely used in many fields such as food, chemical industry, pharmacy, agriculture and so on. The seed is the most basic and important agricultural capital goods, and seed quality is important for agricultural production. Most methods presently used for seed quality detecting were destructive, slow and needed pretreatment, therefore, developing one kind of method that is simple and rapid has great significance for seed quality testing. This article reviewed the application and trends of NIRS technology in testing of seed constituents, vigor, disease and insect pests etc. For moisture, starch, protein, fatty acid and carotene content, the model identification rates were high as their relative contents were high;for trace organic, the identification rates were low as their relative content were low. The heat-damaged seeds with low vigor were discriminated by NIRS, the seeds stored for different time could also been identified. The discrimination of frost-damaged seeds was impossible. The NIRS could be used to identify health and infected disease seeds, and did the classification for the health degree;it could identify parts of the fungal pathogens. The NIRS could identify worm-eaten and health seeds, and further distinguished the insect species, however the identification effects for small larval and low injury level of insect pests was not good enough. Finally, in present paper existing problems and development trends for NIRS in seed quality detection was discussed, especially the single seed detecting technology which was characteristic of the seed industry, the standardization of its spectral acquisition accessories will greatly improve its applicability..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 346 (2015)
Study on Estimation of Deserts Soil Total Phosphorus Content from Thermal-Infrared Emissivity
HOU Yan-jun, Tashpolat·Tiyip, ZHANG Fei, Mamat·Sawut, and Ilyas·Nurmemet
Soil phosphorus provides nutrient elements for plants, is one of important parameters for evaluating soil quality. The traditional method for soil total phosphorus content (STPC) measurement is not effective and time-consuming. However, remote sensing (RS) enables us to determine STPC in a fast and efficient way. StudiSoil phosphorus provides nutrient elements for plants, is one of important parameters for evaluating soil quality. The traditional method for soil total phosphorus content (STPC) measurement is not effective and time-consuming. However, remote sensing (RS) enables us to determine STPC in a fast and efficient way. Studies on the estimation of STPC in near-infrared spectroscopy have been developed by scholars, but model accuracy is still poor due to the low absorption coefficient and unclear absorption peak of soil phosphorus in near-infrared. In order to solve the deficiency which thermal-infrared emissivity estimate desert soil total phosphorus content, and could improve precision of estimation deserts soil total phosphorus. In this paper, characteristics of soil thermal-infrared emissivity are analyzed on the basis of laboratory processing and spectral measurement of deserts soil samples from the eastern Junggar Basin. Furthermore, thermal-infrared emissivity based RS models for STPC estimation are established and accuracy assessed. Results show that: when STPC is higher than 0.200 g·kg-1, the thermal-infrared emissivity increases with the increase of STPC on the wavelength between 8.00 μm and 13 μm, and the emissivity is more sensitive to STPC on the wavelength between 9.00 and 9.6 μm;the estimate mode based on multiple stepwise regression was could not to estimate deserts soil total phosphorus content from thermal-infrared emissivity because the estimation effects of them were poor. The estimation accuracy of model based on partial least squares regression is higher than the model based on multiple stepwise regression. However, the accuracy of second-order differential estimation model based on partial least square regression is higher than based on multiple stepwise regression;The first differential of continuous remove estimation model based on partial least squares regression is the best model with R2 of correction and verification are up to 0.97 and 0.82 respectively, and RMSE of correction and verification are only 0.010 6 and 0.015 7 respectively, RPD is 2.62. Research results provide optimized models for remotely sensed analysis on deserts soil total phosphorus content and could realize timeliness and effective monitoring on the space-time dynamic of deserts soil total phosphorus content for future regional ecological restoration..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 350 (2015)
Determining the Zn Content of Cherry in Field Using VNIR Spectroscopy
Mert Dedeolu, and Levent Basayiit
Visible and near-infrared (VNIR) spectroscopy is an eco-friendly method used for estimating plant nutrient deficiencies. The aim of this study was to investigate the possibility of using VNIR method for estimating Zn content in cherry orchard leaves under field conditions. The study was conducted in 3 different locatioVisible and near-infrared (VNIR) spectroscopy is an eco-friendly method used for estimating plant nutrient deficiencies. The aim of this study was to investigate the possibility of using VNIR method for estimating Zn content in cherry orchard leaves under field conditions. The study was conducted in 3 different locations in Isparta region of Turkey. Fifteen cherry orchards containing normal and Zn deficient plants were chosen, and 60 leaf samples were collected from each location. The reflectance spectra of the leaves were measured with an ASD FieldSpec HandHeld spectroradiometer and a plant probe. The Zn contents of leaf samples were predicted through laboratory analysis. The spectral reflectance measurements were used to estimate the Zn levels using stepwise multiple linear regression analysis method. Prediction models were created using the highest coefficient of determination value. The results show that Zn content of cherry trees can be estimated using the VNIR spectroscopic method (87.5
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 355 (2015)
Apply Fourier Transform Infrared Spectra Coupled with Two-Dimensional Correlation Analysis to Study the Evolution of Humic Acids During Composting
BU Gui-jun, YU Jing, DI Hui-hui, LUO Shi-jia, ZHOU Da-zhai, and XIAO Qiang
The composition and structure of humic acids formed during composting play an important influence on the quality and mature of compost. In order to explore the composition and evolution mechanism, municipal solid wastes were collected to compost and humic and fulvic acids were obtained from these composted municipal soThe composition and structure of humic acids formed during composting play an important influence on the quality and mature of compost. In order to explore the composition and evolution mechanism, municipal solid wastes were collected to compost and humic and fulvic acids were obtained from these composted municipal solid wastes. Furthermore, fourier transform infrared spectra and two-dimensional correlation analysis were applied to study the composition and transformation of humic and fulvic acids during composting. The results from fourier transform infrared spectra showed that, the composition of humic acids was complex, and several absorbance peaks were observed at 2 917～2 924, 2 844～2 852, 2 549, 1 662, 1 622, 1 566, 1 454, 1 398, 1 351, 990～1 063, 839 and 711 cm-1. Compared to humic acids, the composition of fulvci acids was simple, and only three peaks were detected at 1 725, 1 637 and 990 cm-1. The appearance of these peaks showed that both humic and fulvic acids comprised the benzene originated from lignin and the polysaccharide. In addition, humic acids comprised a large number of aliphatic and protein which were hardly detected in fulvic acids. Aliphatic, polysaccharide, protein and lignin all were degraded during composting, however, the order of degradation was different between humic and fulvci acids. The result from two-dimensional correlation analysis showed that, organic compounds in humic acids were degraded in the following sequence: aliphatic>protein> polysaccharide and lignin, while that in fulvic acids was as following: protein> polysaccharide and aliphatic. A large number of carboxyl, alcohols and ethers were formed during the degradation process, and the carboxyl was transformed into carbonates. It can be concluded that, fourier transform infrared spectra coupled with two-dimensional correlation analysis not only can analyze the function group composition of humic substances, but also can characterize effectively the degradation sequence of these groups and identified the formation mechanism and dynamics of humic substances during composting..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 362 (2015)
Identification and Classification of Disease Severity of Wheat Stripe Rust Using Near Infrared Spectroscopy Technology
LI Xiao-long, QIN Feng, ZHAO Long-lian, LI Jun-hui, MA Zhan-hong, and WANG Hai-guang
Wheat stripe rust caused by Puccinia striiformis f. sp. tritici, is an economically important disease in the world. It is of great significance to assess disease severity of wheat stripe rust quickly and accurately for monitoring and controlling the disease. In this study, wheat leaves infected with stripe rust pathogeWheat stripe rust caused by Puccinia striiformis f. sp. tritici, is an economically important disease in the world. It is of great significance to assess disease severity of wheat stripe rust quickly and accurately for monitoring and controlling the disease. In this study, wheat leaves infected with stripe rust pathogen under different severity levels were acquired through artificial inoculation in artificial climate chamber. Thirty wheat leaves with disease severity equal to 1%, 5%, 10%, 20%, 40%, 60%, 80% or 100% were picked out, respectively, and 30 healthy leaves were chosen as controls. A total of 270 wheat leaves were obtained and then their near infrared spectra were measured using MPA spectrometer. According to disease severity levels, 270 near infrared spectra were divided into 9 categories and each category included 30 spectra. From each category, 7 or 8 spectra were randomly chosen to make up the testing set that included 67 spectra. The remaining spectra were treated as the training set. A qualitative model for identification and classification of disease severity of wheat stripe rust was built using near infrared reflectance spectroscopy (NIRS) technology combined with discriminant partial least squares (DPLS). The effects of different preprocessing methods of obtained spectra, ratios between training sets and testing sets, and spectral ranges on qualitative recognition results of the model were investigated. The optimal model based on DPLS was built using cross verification method in the spectral region of 4 000～9 000 cm-1 when “centralization” was used as the preprocessing method of spectra and the spectra were divided into the training set and the testing set with the ratio equal to 3∶1. Accuracy rate of the training set was 95.57% and accuracy rate of the testing set was 97.01%. The results showed that good recognition performance could be acquired using the model based on DPLS. The results indicated that the method using near infrared reflectance spectroscopy technology proposed in this study is feasible for identification and classification of disease severity of wheat stripe rust. A new method was provided for monitoring and assessment of wheat stripe rust..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 367 (2015)
Near-Infrared Spectra Combining with CARS and SPA Algorithms to Screen the Variables and Samples for Quantitatively Determining the Soluble Solids Content in Strawberry
LI Jiang-bo, GUO Zhi-ming, HUANG Wen-qian, ZHANG Bao-hua, and ZHAO Chun-jiang
In using spectroscopy to quantitatively or qualitatively analyze the quality of fruit, how to obtain a simple and effective correction model is very critical for the application and maintenance of the developed model. Strawberry as the research object, this research mainly focused on selecting the key variables and chaIn using spectroscopy to quantitatively or qualitatively analyze the quality of fruit, how to obtain a simple and effective correction model is very critical for the application and maintenance of the developed model. Strawberry as the research object, this research mainly focused on selecting the key variables and characteristic samples for quantitatively determining the soluble solids content. Competitive adaptive reweighted sampling (CARS) algorithm was firstly proposed to select the spectra variables. Then, Samples of correction set were selected by successive projections algorithm (SPA), and 98 characteristic samples were obtained. Next, based on the selected variables and characteristic samples, the second variable selection was performed by using SPA method. 25 key variables were obtained. In order to verify the performance of the proposed CARS algorithm, variable selection algorithms including Monte Carlo-uninformative variable elimination (MC-UVE) and SPA were used as the comparison algorithms. Results showed that CARS algorithm could eliminate uninformative variables and remove the collinearity information at the same time. Similarly, in order to assess the performance of the proposed SPA algorithm for selecting the characteristic samples, SPA algorithm was compared with classical Kennard-Stone algorithm. Results showed that SPA algorithm could be used for selection of the characteristic samples in the calibration set. Finally, PLS and MLR model for quantitatively predicting the SSC (soluble solids content) in the strawberry were proposed based on the variables/samples subset (25/98), respectively. Results show that models built by using the 0.59% and 65.33% information of original variables and samples could obtain better performance than using the ones obtained by using all information of the original variables and samples. MLR model was the best with R2pre=0.909 7, RMSEP=0.348 4 and RPD=3.327 8..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 372 (2015)
Attenuated Total Reflection-Fourier Transform Infrared Spectroscopic Study of Dried Shark Fin Products
HAN Wan-qing, LUO Hai-ying, XIAN Yan-ping, LUO Dong-hui, MU Tong-na, and GUO Xin-dong
Sixty-four pieces of shark fin dried products (including real, fake and artificial shark fin products) and real products coated with gelatin were rapidly and nondestructively analyzed by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). The characteristic of IR spectrograms among the aboveSixty-four pieces of shark fin dried products (including real, fake and artificial shark fin products) and real products coated with gelatin were rapidly and nondestructively analyzed by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). The characteristic of IR spectrograms among the above four kinds of samples were systematically studied and comparied, the results showed that the spectrograms of the same kind of samples were repeatable, and different kinds of shark fin products presented significant differences in the spectrograms, which mainly manifested as the specific absorption peaks of amido bonds in protein (1 650, 1 544 cm-1) and skeletal vibration in polysaccharide (1 050 cm-1). The spectrograms of real shark fins were characterized by the strong absorption peaks of protein characteristic amide Ⅰ and Ⅱ absorbent (1 650, 1 544 cm-1) and relatively weak C—O—C vibration absorbent (1 050 cm-1) owing to the high content of protein and relatively low level of polysaccharide. For fake shark fin products that were molded form by mixing together with the offcut of shark, collagen and other substances, the introduction of non-protein materials leaded to the weaker amido bonds absorbent than real products along with a 30 cm-1 blue shift of amide Ⅰ absorbent. Opposite to the real sample, the relatively strong absorption peak of polysaccharide (～1 047 cm-1) and barely existed amide absorbent were the key features of the spectrogram of artificial samples, which was synthersized by polysaccharide like sodium alginate. Real samples coated with gelatin, the peak strength of protein and polysaccharide were decreased simultaneously when the data collection was taken at the surface of sample, while the spectrogram presented no significant difference to real samples when the data was collected in the section. The results above indicated that by analyzing the characteristic of IR spectrograms and the value range of Apro/Apol collected by ATR-FTIR method could perform the undamaged and rapid identification for shark fins..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 379 (2015)
Effect of pH on Circular Dichroism and Raman Spectroscopy of Secondary Structure of β-Casein from Chinese Human Milk
REN Hao-wei, ZHANG Wan-shu, LI Xiang-yi, and LIU Ning
To obtain a structural basis for the β-casein in Chinese human milk, structural transitions of the β-casein in response to variation of pH were investigated using Raman and circular dichroism (CD) spectroscopy. Both methods indicated that the secondary structures of β-casein in the solution were induced by the pH. SecoTo obtain a structural basis for the β-casein in Chinese human milk, structural transitions of the β-casein in response to variation of pH were investigated using Raman and circular dichroism (CD) spectroscopy. Both methods indicated that the secondary structures of β-casein in the solution were induced by the pH. Secondary structural analysis of β-casein by CD spectroscopy yielded 0.5%~2% α-helical, 16%~18% β-sheet, 30%~34% β-turn and 49%~51% random coil contents. Another result was that as pH increases, these structures change. Several distinct transitions were observed by circular dichroism in α-helix at pH 8 and pH 10. Raman spectrum also showed random coil as the major secondary structure in native β-casein, for the characteristic band of the β-casein amide I was at 1 662 cm-1. Calculations from I850/I830 suggested that the tyrosine residues of β-casein tended to “exposure”. CD and Raman spectra both showed that at neutral and alkaline pH the β-casein existed predominantly in random coil conformation, and the proportion of α-helix was higher at pH 8 than under other pH conditions. Over the range of pH studied, the sheet and turn areas remained relatively constant, and in the condition of pH 8, the content of α-helical was higher than in the other pH conditions..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 384 (2015)
Quantitative Analysis of Thiram by Surface-Enhanced Raman Spectroscopy Combined with Feature Extraction Algorithms
ZHANG Bao-hua, JIANG Yong-cheng, SHA Wen, ZHANG Xian-yi, and CUI Zhi-feng
Three feature extraction algorithms, such as the principal component analysis (PCA), the discrete cosine transform (DCT) and the non-negative factorization (NMF), were used to extract the main information of the spectral data in order to weaken the influence of the spectral fluctuation on the subsequent quantitative anThree feature extraction algorithms, such as the principal component analysis (PCA), the discrete cosine transform (DCT) and the non-negative factorization (NMF), were used to extract the main information of the spectral data in order to weaken the influence of the spectral fluctuation on the subsequent quantitative analysis results based on the SERS spectra of the pesticide thiram. Then the extracted components were respectively combined with the linear regression algorithm—the partial least square regression (PLSR) and the non-linear regression algorithm—the support vector machine regression (SVR) to develop the quantitative analysis models. Finally, the effect of the different feature extraction algorithms on the different kinds of the regression algorithms was evaluated by using 5-fold cross-validation method. The experiments demonstrate that the analysis results of SVR are better than PLSR for the non-linear relationship between the intensity of the SERS spectrum and the concentration of the analyte. Further, the feature extraction algorithms can significantly improve the analysis results regardless of the regression algorithms which mainly due to extracting the main information of the source spectral data and eliminating the fluctuation. Additionally, PCA performs best on the linear regression model and NMF is best on the non-linear model, and the predictive error can be reduced nearly three times in the best case. The root mean square error of cross-validation of the best regression model (NMF+SVR) is 0.045 5 μmol·L-1 (10-6 mol·L-1), and it attains the national detection limit of thiram, so the method in this study provides a novel method for the fast detection of thiram. In conclusion, the study provides the experimental references the selecting the feature extraction algorithms on the analysis of the SERS spectrum, and some common findings of feature extraction can also help processing of other kinds of spectroscopy..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 390 (2015)
Research on Volatiles of Rakkyo (Allium Chinense G. Don) and Chinese Chive (Allium Tuberosum Rottl. ex Sprengel) Based on Headspace and the Molecular Recognition of SERS
ZHANG Chuan-yun, SI Min-zhen, LI Lun, and ZHANG De-qing
The headspace and the molecular recognition of surface enhanced Raman scattering (SERS) were used to research volatiles of rakkyo and Chinese chive. Their volatiles SERS spectra were obtained using nano-silver colloid as the substrate$ Then, volatiles SERS spectra of rakkyo and Chinese Chive were compared respectively The headspace and the molecular recognition of surface enhanced Raman scattering (SERS) were used to research volatiles of rakkyo and Chinese chive. Their volatiles SERS spectra were obtained using nano-silver colloid as the substrate$ Then, volatiles SERS spectra of rakkyo and Chinese Chive were compared respectively with the volatiles SERS spectra of liquid allyl methyl sulfide, 1-propanethiol, diallyl disulfide and all possible pairings of the three compounds. The results showed that the repeatability of volatiles SERS spectra of rakkyo and Chinese Chive were all good. The volatiles SERS spectrum of rakkyo was basically consistent with the volatiles SERS spectrum of the mixture of liquid allyl methyl sulfide and 1-propanethiol. The volatiles SERS spectrum of rakkyo included both characteristic peaks at 626 and 674 cm-1 in volatiles SERS spectrum of allyl methyl sulfide and characteristic peaks at 702, 893, 1 024, 1 085, 1 215 and 1 320 cm-1 in volatiles SERS spectrum of 1-Propanethiol. The volatiles SERS spectrum of Chinese chive was basically consistent with the volatiles SERS spectrum of the mixture of liquid allyl methyl sulfide and diallyl disulfide. The volatiles SERS spectrum of Chinese chive included both characteristic peak at 674 cm-1 in volatiles SERS spectrum of allyl methyl sulfide and characteristic peaks at 407, 577, 716, 1 189, 1 291 and 1 401 cm-1 in volatiles SERS spectrum of diallyl disulfide. These illustrated that volatiles of rakkyo contained allyl methyl sulfide and 1-Propanethiol and volatiles of Chinese chive contained allyl methyl sulfide and diallyl disulfide. The volatiles of rakkyo and Chinese chive were different, but they all contained allyl methyl sulfide. All of the above have revealed that the headspace combined with molecular recognition of SERS can be directly used to study volatiles of rakkyo and Chinese chive. The technology under room temperature, can guarantee the volatiles obtained were the primitive constituents in plant volatiles. By comparison with the standard sample, the constituents in plant volatiles can be determined..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 394 (2015)
Component Analysis of the Circulating Fluid in an Adsorption Tower in a P-Xylene Unit Based on Raman Spectral Decomposition
WANG Bin, and DAI Lian-kui
In order to achieve fast and accurate online analysis of the circulating fluid in an adsorption tower in a p-xylene unit, the Raman spectral analysis method is adopted. However, the Raman spectra of the pure components included in the circulating fluid overlap together, and the concentration of each component varies obIn order to achieve fast and accurate online analysis of the circulating fluid in an adsorption tower in a p-xylene unit, the Raman spectral analysis method is adopted. However, the Raman spectra of the pure components included in the circulating fluid overlap together, and the concentration of each component varies obviously, the present Raman analysis technology needs a large amount of training samples. Therefore, this paper applies Raman spectral decomposition method in component analysis of the circulating fluid. First of all, the Raman spectra of the pure components and the spectra of a few training samples must be measured, and baseline subtraction and mean normalization are applied to obtain pretreated Raman spectra. Then the characteristic wave number range, 680～880cm-1, is chosen, and the Raman spectral decomposition method is adopted, to get decomposition coefficients of each component for each training sample. Next, the mathematical model between coefficients and concentrations of each component are built based on all training samples. For a testing sample, the above spectral pretreatment and the spectral decomposition for the same wave number range is adopted, then the decomposition coefficients of each component can be obtained. Based on the built mathematical model, the concentrations of all components can be predicted. Experimental results show that the standard prediction errors for the concentration of toluene, ethylbenzene, p-xylene, m-xylene, o-xylene and p-diethylbenzene are 0.301%, 0.088%, 0.563%, 0.384%, 0.366% and 0.536% respectively. The above method provides a methodological basis for the online analysis of the circulating fluid in adsorption towers..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 399 (2015)
Surface-Enhanced Raman Spectroscopy Analysis of Thiabendazole Pesticide
LIN Lei, WU Rui-mei, LIU Mu-hua, WANG Xiao-bin, and YAN Lin-yuan
Surface-enhanced Raman spectroscopy (SERS) technique was used to analyze the Raman peaks of thiabendazole pesticides in the present paper. Surface enhanced substrates of silver nanoparticle were made based on microwave technology. Raman signals of thiabendazole were collected by laser Micro-Raman spectrometer with 514.Surface-enhanced Raman spectroscopy (SERS) technique was used to analyze the Raman peaks of thiabendazole pesticides in the present paper. Surface enhanced substrates of silver nanoparticle were made based on microwave technology. Raman signals of thiabendazole were collected by laser Micro-Raman spectrometer with 514.5 and 785 nm excitation wavelengths, respectively. The Raman peaks at different excitation wavelengths were analyzed and compared. The Raman peaks 782 and 1 012 at 785 nm excitation wavelength were stronger, which were C—H out-of-plane vibrations. While 1 284, 1 450 and 1 592 cm-1 at 514.5 nm excitation wavelength were stronger, which were νring and CN stretching. The study results showed that the intensity of Raman peak and Raman shift at different excitation wavelengths were different. And strong Raman signals were observed at 782, 1 012, 1 284, 1 450 and 1 592 cm-1 at 514.5 and 785 nm excitation wavelengths. These characteristic vibrational modes are characteristic Raman peaks of carbendazim pesticide. The results can provide basis for the rapid screening of pesticide residue in agricultural products and food based on Raman spectrum..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 404 (2015)
Effect of Temperature on the Aggregation Behavior of Collagen Solution by Two-Dimensional Synchronous Fluorescence Correlation Spectroscopy
WU Wan-ye, WU Kun, and LI Guo-ying
The synchronous fluorescence spectroscopy and two dimensional correlation analysis method were applied to study the aggregation behavior of acid-soluble collagen solutions (0.2, 0.4 and 1.6 mg·mL-1) during the heating process of 10～70 ℃. It was found that the fluorescence excited at 292 and 282 nm (Δλ=9 nm) belongThe synchronous fluorescence spectroscopy and two dimensional correlation analysis method were applied to study the aggregation behavior of acid-soluble collagen solutions (0.2, 0.4 and 1.6 mg·mL-1) during the heating process of 10～70 ℃. It was found that the fluorescence excited at 292 and 282 nm (Δλ=9 nm) belongs to the tyrosine (Tyr) residues which participate in forming hydrogen bonds or not, respectively. The two dimensional correlation analysis with the temperature varying showed that with the temperature increased (10～30 ℃) hydrogen bonds among collagen molecular with Tyr residues formed in the 0.2 mg·mL-1 collagen solution, while the higher aggregations of collagen molecular and hydrophobic micro-domains appeared in the 0.4 and 1.6 mg·mL-1 collagen solutions. With approaching the denatured temperature of collagen (36～38 ℃), the hydrophobic micro-domain and aggregates seemed to be broken in the 0.4 and 1.6 mg·mL-1 collagen solutions, however the hydrogen bonds in the 0.2 mg·mL-1 were stable. Above the denaturation temperature of collagen, the triple-helix structure of collagen molecular in solution of each concentration tended to be loose. In the heating process of 45～70 ℃, this trend was more obvious..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 409 (2015)
Study on Fluorescence Spectra of Chlorothalonil Residues and the Interaction between Chlorothalonil and Chinese Herbal Medicines
JI Ren-dong, ZHAO Zhi-min, CHEN Meng-lan, WANG Le-xin, and ZHU Xing-yue
The fluorescence spectrum was studied for the chlorothalonil(0.292 8 mg·mL-1) using spectrofluorophotometer. The experiment results showed that the characteristic peaks (352 and 366 nm) are found in the spectrum of chlorothalonil standard solution when the excitation wavelength is 320 nm. And it was found that theThe fluorescence spectrum was studied for the chlorothalonil(0.292 8 mg·mL-1) using spectrofluorophotometer. The experiment results showed that the characteristic peaks (352 and 366 nm) are found in the spectrum of chlorothalonil standard solution when the excitation wavelength is 320 nm. And it was found that the shoulder peak gradually disappeared at 366 nm, while the fluorescence peak is stable at 352 nm with the decline of the solution concentration. The exponential functional relationship between the concentration of chlorothalonil and fluorescence intensity at 352 nm was obtained, and its correlation coefficient is 0.999. The experimental results are consistent with the theoretical formula about fluorescence intensity and concentration. The prediction model functions were also obtained through the liner fitting to the chlorothalonil solution of low concentration, and the correlation coefficient is 0.995. The limit of detection (LOD) is 0.018 8 μg·mL-1, the limit of quantification (LOQ) is 0.062 7 μg·mL-1, and the linear range is 0.062 7～28.45 μg·mL-1. And fluorescence spectra were studied for the mixed system of astragalus, medlar and chlorothalonil. It was found that the fluorescence intensity of chlorothalonil solution is all declined with the addition of two kinds of Chinese Herbal Medicines, which indicates that there is an interaction between them. The decay rate of fluorescence intensity was obtained which is 88.5% and 99.7%, respectively. Then the model functions were established between fluorescence intensity and the volume of addition, and the correlation coefficient is 0.994 and 0.997, respectively. This study provides the experimental foundation for the detection of chlorothalonil residues using fluorescence spectrum. It is shown that it is possible to detect pesticide residues of chlorothalonil using fluorescence spectra directly, and the relevant parameter value satisfied the requirement of testing standard. Therefore there is an important value for further detecting the pesticide residues in fruit juice using fluorescence spectrum. It was also found that the fluorescence intensity of chlorothalonil is decreased with the addition of astragalus or medlar, which provides the new research approach to studying the pesticide degradation using medicinal and edible Chinese Herbal Medicines..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 415 (2015)
Effect of Quantum Dots CdSe/ZnS’s Concentration on Its Fluorescence
JIN Min, HUANG Yu-hua, and LUO Ji-xiang
The authors measured the absorption and the fluorescence spectra of the quantum dots CdSe/ZnS with 4 nm in size at different concentration with the use of the UV-Vis absorption spectroscopy and fluorescence spectrometer. The effect of quantum dots CdSe/ZnS’s concentration on its fluorescence was especially studied and The authors measured the absorption and the fluorescence spectra of the quantum dots CdSe/ZnS with 4 nm in size at different concentration with the use of the UV-Vis absorption spectroscopy and fluorescence spectrometer. The effect of quantum dots CdSe/ZnS’s concentration on its fluorescence was especially studied and its physical mechanism was analyzed. It was observed that the optimal concentration of the quantum dots CdSe/ZnS for fluorescence is 2 μmol·L-1. When the quantum dot’s concentration is over 2 μmol·L-1, the fluorescence is decreased with the increase in the concentration. While the quantum dot’s concentration is less than 2 μmol·L-1, the fluorescence is decreased with the decrease in the concentration. There are two main reasons: 1) fluorescence quenching and 2) the competition between absorption and fluorescence. When the quantum dot’s concentration is over 2 μmol·L-1, the distance between quantum dots is so close that the fluorescence quenching is induced. The closer the distance between quantum dots is, the more serious the fluorescence quenching is induced. Also, in this case, the absorption is so large that some of the quantum dots can not be excited because the incident light can not pass through the whole sample. As a result, the fluorescence is decreased with the increase in the quantum dot’s concentration. As the quantum dot’s concentration is below 2 μmol·L-1, the distance between quantum dots is far enough that no more fluorescence quenching is induced. In this case, the fluorescence is determined by the particle number per unit volume. More particle number per unit volume produces more fluorescence. Therefore, the fluorescence is decreased with the decrease in the quantum dot’s concentration..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 420 (2015)
Study on the Concentration of Mineral Oil in Water by Online Intelligent Detection Based on Fluorescence Spectrum
Tang Yuanhe, Liu Qingsong, Meng Lei, Liu Hanchen, Liu Qian, and Li Cunxia
In order to monitor the oil pollution of water real time and accurately for the environmental protection, an intelligent online detection system for the mineral oil in water is put forward in the present paper, based on the technology of ultraviolet fluorescence and internet of things (IOT). For this system, the resoluIn order to monitor the oil pollution of water real time and accurately for the environmental protection, an intelligent online detection system for the mineral oil in water is put forward in the present paper, based on the technology of ultraviolet fluorescence and internet of things (IOT). For this system, the resolution can be improved by using the higher precision asymmetric Czemy-Turner monochromator;the impact of light fluctuations on the results of exploration can be corrected by a bunch reference light;the optical system deviation caused by the instrument vibration can be reduced by optical fiber transmission;the coupling efficiency of fiber and output signal can be increased by a special fiber beam;the real-time measurement, data processing and remote control can be achieved by the control module and wireless communication module. This system has characteristics of high integration, high precision and good stability etc. The concentration of the unknown sample can be accurately calculated by the methods of parallel algorithms of chemometric metrology and the calculation errors caused by different components can be reduced by the theory of chemical correction factor analysis. The fluorescence spectra of three kinds of sample solution, diesel, engine and crude oil in preparative concentration of 10, 25, 50 and 100 mg·L-1 were measured by this system respectively. The absorption wavelengths of the above-mentioned three oils were measured to be 256, 365 and 397 nm by a grating spectrometer;their absorbances were measured to be 0.028, 0.036 and 0.041 by fluorescence spectrophotometer, respectively. Their fluorescence emission wavelengths are 355, 419 and 457 nm respectively. Finally the concentration detection limits of the mineral oil in water of diesel, engine and crude oil were obtained, i.e. 0.03, 0.04 and 0.06 mg·L-1 respectively. Their relative errors are 2.1%, 1.0% and 2.8% respectively..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 424 (2015)
STR Fluorescence Spectral Analysis Based on Matrix Analysis
LI Bin, ZHANG Tao, and JIA Er-hui
In a detection system of STR labeled by multiple fluorescence, the overlaps do occur between the different colored fluorophores owing to the band broadening characteristic of the employed fluorescence spectrum. It is crucial to obtain effective energy distribution specific for different wavelengths so as to improve theIn a detection system of STR labeled by multiple fluorescence, the overlaps do occur between the different colored fluorophores owing to the band broadening characteristic of the employed fluorescence spectrum. It is crucial to obtain effective energy distribution specific for different wavelengths so as to improve the utilization efficiency of fluorescence intensity. To reach this goal in practice, we propose a data processing method based on matrix analysis. Firstly,a spectral calibration must be done for STR fluorescence spectral analysis, and then a emission spectral distribution of each colored fluorophore excitated by laser is created from the detection signal. And then, the matrix normalization is computed from the above fixed spectrum distribution. And lastly, the inversion of the correct matrix is used to get the resolved and desirable STR spectrogram. In addition, performance evaluation shows that this method based on matrix analysis can make use of the fluorescence spectrum energy of each wavelength and resolve the overlapping spectrum effectively..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 429 (2015)
Derivative Fluorescence Probe Recognition Results of the Light Physical Mechanism of Metal Ions
DAI Yu-mei, HU Xiao-jun, LI Fu-jun, XIE Yu-meng, ZHAO Yang-yang, and ZHOU Qiao
As people deeply study the electronic spectra of fluorescent compounds and photophysical behavior, enormous progress has been made in the aspect of changes and states of different systems in the use of fluorescent molecules as probes. PTCDA is a kind of typical fluorescent molecular probe that is highly sensitive and sAs people deeply study the electronic spectra of fluorescent compounds and photophysical behavior, enormous progress has been made in the aspect of changes and states of different systems in the use of fluorescent molecules as probes. PTCDA is a kind of typical fluorescent molecular probe that is highly sensitive and selective in water environment. This paper makes a research on the physical mechanism of light of PTCDA by TDF (Density Functional Theory), calculates the optimal configuration the charge population and excitation spectra of PTCDA molecules under ideal condition and acquires PTCDA fluorescence emission spectra then analyses that PTCDA is a kind of quenching and dual colorimetric signal probe response. Its optical signal response mechanism belongs to ICT( Intramolecular Charge Transfer) mechanism. According to the results, this perylene derivatives is fitted with Cu2+ excited state absorption spectra. Before and after the combination with Cu2+, the peak shape of absorption spectrum is similar. When copper is added, the overall absorption peak position occurred redshift, quenching discoloration happens. By comparing with experimental values, the calculated molecular configuration is reasonable and effective and the peak of excitation spectra is realistic. Analysis shows that: PTCDA molecules divalent copper ions have better fluorescence detection activity, the optical signal response mechanisms are intramolecular charge transfer (ICT) mechanisms. When a molecule receives divalent copper ions, the absorption spectrum peak position redshifts, intramolecular charge transfer direction and intensity changes. There occur both quenching signal and discoloration signal. It is a kind of fluorescent probe material with double quenching and discoloration fluorescent signal, which has great potential for development. This paper makes an early-stage exploration of the physical mechanism of light response mechanism analysis in molecular fluorescent probe field and can be a systematically valuable theoretical reference for this field..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 433 (2015)
Early Warning for Various Internal Faults of GIS Based on Ultraviolet Spectroscopy
ZHAO Yu, WANG Xian-pei, HU Hong-hong, DAI Dang-dang, LONG Jia-chuan, TIAN Meng, ZHU Guo-wei, and HUANG Yun-guang
As the basis of accurate diagnosis, fault early-warning of gas insulation switchgear (GIS) focuses on the time-effectiveness and the applicability. It would be significant to research the method of unified early-warning for partial discharge (PD) and overheated faults in GIS. In the present paper, SO2 is proposed as thAs the basis of accurate diagnosis, fault early-warning of gas insulation switchgear (GIS) focuses on the time-effectiveness and the applicability. It would be significant to research the method of unified early-warning for partial discharge (PD) and overheated faults in GIS. In the present paper, SO2 is proposed as the common and typical by-product. The unified monitoring could be achieved through ultraviolet spectroscopy (UV) detection of SO2. The derivative method and Savitzky-Golay filtering are employed for baseline correction and smoothing. The wavelength range of 290～310 nm is selected for quantitative detection of SO2. Through UV method, the spectral interference of SF6 and other complex by-products, e.g. SOF2 and SOF2, can be avoided and the features of trace SO2 in GIS can be extracted. The detection system is featured by compacted structure, low maintenance and satisfactory suitability in filed surveillance. By conducting SF6 decomposition experiments, including two types of PD faults and the overheated faults between 200～400 ℃, the feasibility of proposed UV method has been verified. Fourier transform infrared spectroscopy and gas chromatography methods can be used for subsequent fault diagnosis. The different decomposition features in two kinds of faults are confirmed and the diagnosis strategy has been briefly analyzed. The main by-products under PD are SOF2 and SO2F2. The generated SO2 is significantly less than SOF2. More carbonous by-products will be generated when PD involves epoxy. By contrast, when the material of heater is stainless steel, SF6 decomposes at about 300 ℃ and the main by-products in overheated faults are SO2 and SO2F2. When heated over 350 ℃, SO2 is generated much faster. SO2 content stably increases when the GIS fault lasts. The faults types could be preliminarily identified based on the generation features of SO2..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 438 (2015)
Pattern Recognition of Decorative Papers with Different Visual Characteristics Using Visible Spectroscopy Coupled with Principal Component Analysis(PCA)
ZHANG Mao-mao, YANG Zhong, LV Bin, LIU Ya-na, and SUN Xue-dong
As one of the most important decorative materials for the modern household products, decorative papers impregnated with melamine not only have better decorative performance, but also could greatly improve the surface properties of materials. However, the appearance quality (such as color-difference evaluation and contrAs one of the most important decorative materials for the modern household products, decorative papers impregnated with melamine not only have better decorative performance, but also could greatly improve the surface properties of materials. However, the appearance quality (such as color-difference evaluation and control) of decorative papers, as an important index for the surface quality of decorative paper, has been a puzzle for manufacturers and consumers. Nowadays, human eye is used to discriminate whether there exist color difference in the factory, which is not only of low efficiency but also prone to bring subjective error. Thus, it is of great significance to find an effective method in order to realize the fast recognition and classification of the decorative papers. In the present study, the visible spectroscopy coupled with principal component analysis (PCA) was used for the pattern recognition of decorative papers with different visual characteristics to investigate the feasibility of visible spectroscopy to rapidly recognize the types of decorative papers. The results showed that the correlation between visible spectroscopy and visual characteristics (L*, a* and b*) was significant, and the correlation coefficients were up to 0.85 and some was even more than 0.99, which might suggest that the visible spectroscopy reflected some information about visual characteristics on the surface of decorative papers. When using the visible spectroscopy coupled with PCA to recognize the types of decorative papers, the accuracy reached 94%～100%, which might suggest that the visible spectroscopy was a very potential new method for the rapid, objective and accurate recognition of decorative papers with different visual characteristics..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 443 (2015)
Spectrum Characteristics of Leaching Components from Co-Contaminated Loess in Ex-Situ Column Washing Reaction
FAN Chun-hui, ZHANG Ying-chao, DU Bo, HE Lei, and WANG Jia-hong
Soil contamination is regarded as one of the most serious issues to humanity all over the world. It is statistically believed that over one-fifth of the farmland, that is 20 million ha, is found to be contaminated by heavy metals in China. And the related issues, caused by soil contamination, of food safety, human healSoil contamination is regarded as one of the most serious issues to humanity all over the world. It is statistically believed that over one-fifth of the farmland, that is 20 million ha, is found to be contaminated by heavy metals in China. And the related issues, caused by soil contamination, of food safety, human health and eco-environmental quality attract much attention by public with more serious contamination than before. The technological approach for soil remediation is widely investigated. The technology of soil washing is effective for contaminants removal, while the treatment procedure might lead to component leaching from soil system, harmful for soil fertility, physicochemical properties and ecological functions. The study of spectral characteristics on leaching component is significant for decision-making of contaminated sites remediation and ecological function recovery, while the related investigation seems weaker nowadays. The paper mainly revealed the leaching characteristics of component from Pb/Cd contaminated loess in the washing process with Ethylene Diamine Tetraacetic Acid (EDTA) in reaction column, and the research objectives included base cations, loess nutrients, clay minerals and organic matter. The variation of clay minerals was analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM), and 3D-EEM fluorescence spectrum was used for the identification of dissolved organic matter (DOM). The experimental results showed: the leaching component from loess is detected in the washing reaction. The final removal efficiency (240 min) of Pb and Cd from loess are 49.86% and 62.25%, respectively. The sodium ions and nitrate nitrogen are the most easily leaching component, and little difference of clay minerals is identified before and after washing reaction. The fulvic acid-like (FA-like) material was firstly (10 min) detected around Eex/em=240~250/320~340 and Eex/em=260~290/450~470 in 3D-EEM fluorescence spectrum, and the humin acid-like (HA-like, Eex/em=290~320/430~490) appeared at 60 min with weaker fluorescence intensity of FA-like (Eex/em=240/320). The decreased fluorescence intensity of FA-like and HA-like, shown after 120 min and 240 min, indicated the component variation of DOM in the leaching solution. The spectroscopy approach is appropriate for characteristics identification of leaching component from co-contaminated loess..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 447 (2015)
Spectroscopic Study on Film Formation Mechanism and Structure of Composite Silanes-V-Zr Passive Film
WANG Lei, LIU Chang-sheng, SHI Lei, and AN Cheng-qiang
A composite silanes-V-Zr passive film was overlayed on hot-dip galvanized steel. Attenuated total reflection Fourier transformed infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectrometer (XPS) and radio frequency glow discharge optical emission spectrometry (rf-GD-OES) were used to characterize the molecular sA composite silanes-V-Zr passive film was overlayed on hot-dip galvanized steel. Attenuated total reflection Fourier transformed infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectrometer (XPS) and radio frequency glow discharge optical emission spectrometry (rf-GD-OES) were used to characterize the molecular structure of the silanes-V-Zr passive film. The mechanism of film formation was discussed. The results show that the silane molecules are crosslinked as the main film former and inorganic inhibitor is even distributed in the film. The fitting peak of 100.7 eV in XPS single Si2p energy range spectra of the composite silanes-V-Zr passive film and the widening and strengthening of the Si—O infrared absorption peak at 1 100 cm-1 indicate that the silanes were adsorbed on the surface of zinc with chemical bond of Si—O—Zn, and the silane molecules were connected with each other by bond of Si—O—Si. Two characteristic absorption peaks of amide at 1 650 and 1 560 cm-1 appear in the infrared spectroscopy of the composite silanes-V-Zr passive film, and a characteristic absorption peak of epoxy groups at 910 cm-1 disappears in the infrared spectroscopy of the passive film. The results indicate that γ-APT can be prepared through nucleophilic ring-opening of ethylene oxide in γ-GPT molecule to form C—N covalent bonds. The rf-GD-OES results indicate that there is a oxygen enriched layer in 0.3 μm depth of the composite silanes-V-Zr passive film. Moreover, ZrF4, ZrO2 and some inorganic matter obtained by the reaction during the forming process of the composite silanes-V-Zr passive film are distributed evenly throughout the film. According to the film composition, the physical processes and chemical reactions during the film forming process were studied by using ATR-FTIR. Based on this, the film forming mechanism was proposed..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 453 (2015)
Non-Covalent Albumin Conjugates of Silicon(Ⅳ) Phthalocyanines Axially Substituted with Nucleoside: Preparation and in vitro Photodynamic Activities
YANG Xiao-mei, ZHENG Bi-yuan, CAI Yue, LIN Ai-lan, SHEN Xiao-min, ZHANG Han-hui, and HUANG Jian-dong
The interactions of bovine serum albumin (BSA) with five novel silicon (Ⅳ) phthalocyanines(SiPc1-5) axially modified by nucleosides (cytidine, 5-N-cytidine, methyl cytidine, uridine and methyl uridine) derivatives were studied by fluorescence spectroscopy. The results show that there are strong interactions between theThe interactions of bovine serum albumin (BSA) with five novel silicon (Ⅳ) phthalocyanines(SiPc1-5) axially modified by nucleosides (cytidine, 5-N-cytidine, methyl cytidine, uridine and methyl uridine) derivatives were studied by fluorescence spectroscopy. The results show that there are strong interactions between these silicon phthalocyanines and BSA with a binding constant of(4.90~83.18)×105 mol-1·L. Therefore, the non-covalent BSA conjugate of bis(2’,3’-O-isopropyl-cytidine-oxy) phthalocyaninatosilicon(Ⅳ) (SiPc1) was further been prepared. The molar ratio of phthalocyanine to albumin was found to be 1∶1 for the obtained SiPc1-BSA conjugate. The absorption spectra of SiPc1 and SiPc1-BSA in the visible region have no significant difference, both showing an Q-band maximum at about 686 nm. It indicates that the spectroscopic characteristics of SiPc1 are not affected by binding to albumin. The SiPc1-BSA conjugate exhibits high photodynamic activity against human hepatoma cell line HepG2 with an IC50 value of 3.0×10-7 mol·L-1. By comparsion, SiPc1-BSA has a higher photodynamic activity than SiPc1 (in PBS formation, IC50=7.0×10-7 mol·L-1), which can be attributed to its higher cellular uptake..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 457 (2015)
Preparation and Characterization of Kaolinite-Potassium Dihydrogen Phosphate Intercalation Composite
TANG Wu-fei, GU Xiao-yu, ZHANG Sheng, YUAN Hong-fu, JIANG Yu, and ZHAO Jing-ran
Thepotassium dihydrogenphospiate (KDP) intercalated kaolinite (K-KDP) was prepared by a three-step reaction. Firstly, polar dimethyl sulphoxide (DMSO) was introduced into the layers of kaolinite by ultrasonic method and the product K-DMSO was obtained as precursor;secondly DMSO was replaced by potassium acetate (KAc) aThepotassium dihydrogenphospiate (KDP) intercalated kaolinite (K-KDP) was prepared by a three-step reaction. Firstly, polar dimethyl sulphoxide (DMSO) was introduced into the layers of kaolinite by ultrasonic method and the product K-DMSO was obtained as precursor;secondly DMSO was replaced by potassium acetate (KAc) and the product K-KAc was gotten as intermediate;finally KAc was replaced by KDP. The intercalation ratio of the final product K-KDP reached 81.3%. The structure of products at differentreaction process was characterized by Fourier-transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM) in detail. FTIR results showed the existence of PO in the final product but moved from 1 300 to 1 201 cm-1. XRD results documented that the interlayer spacing of kaolinite was enlarged during the whole intercalation reaction. SEM indicated that the agglomeration of kaolinite was destroyed and the particle size distribution became more uniform..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 462 (2015)
Measurements of IR Absorption Across Section and Spectrum Simulation of Lewisite
ZHANG Yuan-peng, WANG Hai-tao, ZHANG Lin, YANG Liu, GUO Xiao-di, BAI Yun, and SUN Hao
The vapor infrared transmission spectra of varied concentration of lewisite-1 were measured by a long-path FT-IR spectrometer, and its characteristic frequencies are 814, 930, 1 563 cm-1;their infrared absorption cross section (σ) were determined using Beer-Lambert law. The corresponding σ values are 3.89±0.01, 1.The vapor infrared transmission spectra of varied concentration of lewisite-1 were measured by a long-path FT-IR spectrometer, and its characteristic frequencies are 814, 930, 1 563 cm-1;their infrared absorption cross section (σ) were determined using Beer-Lambert law. The corresponding σ values are 3.89±0.01, 1.43±0.06, 4.47±0.05(×10-20 cm2·molecule-1). Two little teeny peaks, 1 158, 1 288 cm-1 were found in the measured spectra. Density Functional Theory (DFT) was applied to calculated the infrared spectra of lewisite-1, -2, -3 on a b3lyp/6-311+g(d,p) level by Gauss09 package. The vibration modes were assigned by Gaussview5.08. The calculated spectra and experimental spectra are in good agreement with each other in 600～1 600 cm-1 range, for the Person’s r is 0.999 1. The calculated spectra also showed three characteristic frequencies (293, 360, 374 cm-1) related to As atom. 0.977 was a scaling factor we determined for lewisite-1 through least-square error and its performance to scale lewisite-1, -2, -3 was acceptable. The results of this work are useful for monitoring environmental atmospheric concentrations of lewisite..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 466 (2015)
Synthesis of Naphthalimide Derivatives and Its Recognition of Fe3+
DU Bin, DING Zhi-jun, GUO Lei, WANG Pu-hong, LI Zhi-jun, and YU Jian-hua
A novel naphthalimide derivatives N-hexyl-4-benzylamino-naphthalimide(HBN) was synthesized from 4-bromo-1,8-naphthalic anhydride, and the structure was characterized by NMR and MS. Spectral properties of HBN for recognition of Fe3+ were investigated by fluorescence spectrum. In a certain range of Fe3+ from 4×10-7 A novel naphthalimide derivatives N-hexyl-4-benzylamino-naphthalimide(HBN) was synthesized from 4-bromo-1,8-naphthalic anhydride, and the structure was characterized by NMR and MS. Spectral properties of HBN for recognition of Fe3+ were investigated by fluorescence spectrum. In a certain range of Fe3+ from 4×10-7 to 1×10-2 mol·L-1, the fluorescence intensity of HBN significantly reduced with increasing concentration of Fe3+ in ethanol/water(1∶1, volume ratio). The equation of linear regression was F0/F=623.253 2cFe3++0.964 2 (R2=0.996 3). Moreover, no obvious interference with the detection of the Fe3+ ion was observed in the presence of the common metal ions such as Ca2+, Na+, Cu2+, Zn2+, Pb2+, Co2+, Ni2+, Mn2+ and Fe2+, which indicated that HBN displayed excellent selectivity and high sensitivity for the detection of Fe3+..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 470 (2015)
Piezoresistivity of Ultra-Thin Poly-Silicon Layer by Aluminum-Induced Layer Exchange
WANG Cheng-long, MA Jun, FAN Duo-wang, XING Da, and LIU Song-hao
Poly-Si film, due to its favorable piezoresistive properties, has been widely used in piezoresistive sensors. The previous researches have shown that the ultra-thin poly-Si film have better piezoresistive properties than common poly-silicon film, and have promising future of application. A promising method to obtain laPoly-Si film, due to its favorable piezoresistive properties, has been widely used in piezoresistive sensors. The previous researches have shown that the ultra-thin poly-Si film have better piezoresistive properties than common poly-silicon film, and have promising future of application. A promising method to obtain large grained high quality poly-silicon films by low-temperature crystallization of an amorphous precursor material is the aluminum-induced layer exchange (ALILE). In this paper, ultra-thin poly-Si films were prepared by aluminum induced layer exchange (ALILE). Experimental results of Raman spectroscopy show that a narrow and symmetrical Raman peak at the wave number of about 518 cm-1 was observed for all samples, indicating that the films were fully crystallized. XRD results show that the crystallites of ultra-thin poly-silicon layer were preferably (111) and (220) oriented. Hall affect measurements show that hole concentration of the films (p-type) were between 9×1018 and 6×1019 cm-3. Restorative properties show that the piezoresistors exhibit gauge factors (GFs) up to 60, with temperature coefficients of GF (TCGF) between -0.17～0%℃ and temperature coefficients of resistance (TCR) between -0.2 and -0.1%℃. The study of the ultra-thin poly-Si films by ALILE is completed, and the study results lay a foundation for application of the film to piezoresistive sensor..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 474 (2015)
Research on Identification of Cabbages and Weeds Combining Spectral Imaging Technology and SAM Taxonomy
ZU Qin, ZHANG Shui-fa, CAO Yang, ZHAO Hui-yi, and DANG Chang-qing
Weeds automatic identification is the key technique and also the bottleneck for implementation of variable spraying and precision pesticide. Therefore, accurate, rapid and non-destructive automatic identification of weeds has become a very important research direction for precision agriculture. Hyperspectral imaging syWeeds automatic identification is the key technique and also the bottleneck for implementation of variable spraying and precision pesticide. Therefore, accurate, rapid and non-destructive automatic identification of weeds has become a very important research direction for precision agriculture. Hyperspectral imaging system was used to capture the hyperspectral images of cabbage seedlings and five kinds of weeds such as pigweed, barnyard grass, goosegrass, crabgrass and setaria with the wavelength ranging from 1 000 to 2 500 nm. In ENVI, by utilizing the MNF rotation to implement the noise reduction and de-correlation of hyperspectral data and reduce the band dimensions from 256 to 11, and extracting the region of interest to get the spectral library as standard spectra, finally, using the SAM taxonomy to identify cabbages and weeds, the classification effect was good when the spectral angle threshold was set as 0.1 radians. In HSI Analyzer, after selecting the training pixels to obtain the standard spectrum, the SAM taxonomy was used to distinguish weeds from cabbages. Furthermore, in order to measure the recognition accuracy of weeds quantificationally, the statistical data of the weeds and non-weeds were obtained by comparing the SAM classification image with the best classification effects to the manual classification image. The experimental results demonstrated that, when the parameters were set as 5-point smoothing, 0-order derivative and 7-degree spectral angle, the best classification result was acquired and the recognition rate of weeds, non-weeds and overall samples was 80%, 97.3% and 96.8% respectively. The method that combined the spectral imaging technology and the SAM taxonomy together took full advantage of fusion information of spectrum and image. By applying the spatial classification algorithms to establishing training sets for spectral identification, checking the similarity among spectral vectors in the pixel level, integrating the advantages of spectra and images meanwhile considering their accuracy and rapidity and improving weeds detection range in the full range that could detect weeds between and within crop rows, the above method contributes relevant analysis tools and means to the application field requiring the accurate information of plants in agricultural precision management..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 479 (2015)
Prediction of SPAD Value in Oilseed Rape Leaves Using Hyperspectral Imaging Technique
DING Xi-bin, LIU Fei, ZHANG Chu, and HE Yong
In the present work, prediction models of SPAD value (Soil and Plant Analyzer Development, often used as a parameter to indicate chlorophyll content) in oilseed rape leaves were successfully built using hyperspectral imaging technique. The hyperspectral images of 160 oilseed rape leaf samples in the spectral range of 3In the present work, prediction models of SPAD value (Soil and Plant Analyzer Development, often used as a parameter to indicate chlorophyll content) in oilseed rape leaves were successfully built using hyperspectral imaging technique. The hyperspectral images of 160 oilseed rape leaf samples in the spectral range of 380～1030 nm were acquired.Average spectrum was extracted from the region of interest(ROI) of each sample.We chose spectral data in the spectral range of 500～900 nm for analysis. Using Monte Carlo partial least squares(MC-PLS) algorithm, 13 samples were identified as outliers and eliminated. Based on the spectral information and measured SPAD values of the rest 147 samples, several estimation models have been built based on different parameters using different algorithms for comparison, including: (1) a SPAD value estimation model based on partial least squares(PLS) in the whole wavelength region of 500～900 nm;(2) a SPAD value estimation model based on successive projections algorithmcombined with PLS(SPA-PLS);(3) 4 kind of simple experience SPAD value estimation models in which red edge position was used as an argument;(4) 4 kind of simple experience SPAD value estimation models in which three vegetation indexes R710/R760, (R750－R705)/(R750－R705) and R860/(R550×R708), which all have been proved to have a good relevance with chlorophyll content, were used as an argument respectively;(5) a SPAD value estimation model based on PLS using the 3 vegetation indexes mentioned above. The results indicate that the optimal prediction performance is achieved by PLS model in the whole wavelength region of 500～900 nm, which has a correlation coefficient(rp) of 0.833 9 and a root mean squares error of predicted(RMSEP) of 1.52. The SPA-PLS model can provide avery close prediction result while the calibration computation has been significantly reduced and the calibration speed has been accelerated sharply. For simple experience models based on red edge parameters and vegetation indexes, although there is a slight gap between theprediction performance and that of the PLS model in the whole wavelength region of 500～900 nm, they also have their own unique advantages which should be thought highly of: these models are much simpler and thus the calibration computation is reduced significantly, they can perform an important function under circumstances in which increasing modeling speed and reducing calibration computation operand are more important than improving the prediction accuracy, such as the development of portable devices..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 486 (2015)
Photometric Micro-Titration Model of DPPH Radicals Scavenging Activity and Its Application
GAO Yun-tao, WEI Wei, YE Li-qing, LI Xiao-fen, LIU Ping, ZHANG Hong-jiao, YANG Lu, YU Jiao-jiao, and CHA Jia-wei
In the present paper, the stoichiometric ratio (R) for the interreaction of DPPH radicals with the antoxidant was employed as a evaluation index for DPPH radicals scavenging activity of antioxidants. This evaluation index was related only with the stoichiometric relationship between DPPH radicals and the antioxidant, nIn the present paper, the stoichiometric ratio (R) for the interreaction of DPPH radicals with the antoxidant was employed as a evaluation index for DPPH radicals scavenging activity of antioxidants. This evaluation index was related only with the stoichiometric relationship between DPPH radicals and the antioxidant, not the relationship with the initial DPPH amount and the volume of sample, which could offer a solution for the problem of poor comparability of EC50 under different conditions. A novel photometric micro-titration method was proposed for the determination of the stoichiometric ratio (R) for the interreaction of DPPH radicals with the antoxidant. The titration equation was established based on the absorbance difference (ΔA) of DPPH radicals in the titration process and the added amount of antoxidant. The stoichiometric ratio (R) for the reaction of DPPH radicals with the addition amount of antoxidant was determined by the titration equation obtained, while, the DPPH median elimination concentration (EC50) of antoxidant can be calculated by the stoichiometric ratio (R). The above photometric micro-titration model was verified using rutin as DPPH radicals scavenger. As experiment results, the stoichiometric ratio (R) of DPPH radicals to rutin was determined to be in the range of 1.817～1.846. The calculated value of EC50 was 1.196×10-3, 2.392×10-3, 4.819×10-3 and 7.292×10-3 mg·mL-1 for 1.12×10-7, 2.24×10-7, 4.48×10-7 and 6.72×10-7 mol of the addition amount of DPPH radicals, respectively. The proposed method has better precision and reliability with smaller amount of sample than conventional method. While, the obtained stoichiometric ratio value (R) of rutin was employed to calculate the rutin median elimination concentration for DPPH (EC50) according to the conditions as reported in the literatures, and the calculated results were consistent with that reported in the literatures..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 492 (2015)
The New Applications of NMR Technology in the Field of Characterization of Surface Properties of the Material
LIANG Ni, ZHANG Di, and WEI Chao-xian
Nuclear magnetic resonance (NMR) technology has been developed continuely because of its rapid, accurate and high resolution advantages, The technology has become an important method to analyze the soil properties, and to identify the structure of matters, food analysis, medical imaging fields. This study summarized twNuclear magnetic resonance (NMR) technology has been developed continuely because of its rapid, accurate and high resolution advantages, The technology has become an important method to analyze the soil properties, and to identify the structure of matters, food analysis, medical imaging fields. This study summarized two aspects of the important applications of NMR in the characterization of the surface properties of materials. First, the use of NMR techniques for the adsorption, desorption and diffusion behaviors of polymer on solid particles (mainly SiO2 particles). Sencond, to investigate the wettability and water uptake progress of contaminated soils using NMR techniques. This study summarized the important applications of NMR techniques in the characterization of surface properties. It also showed the unique application in the field of polymer materials and environment. This study introduced the measured method for the relaxation time of substance using acorn surface area analyzer in the liquid environment. It reflect the surface properties and structural features of substance. It also provided data support for the explanation of environmental behaviors of contaminants and thus, it played an important role in the environmental field. Compared to the conventional BET method, acorn surface area analyzer showed the advantages in terms of conditions and time measurement. Especially, traditional BET method cannot get the information of the specific surface area of substances in the liquid directly, but acorn surface area analyzer solved the difficult problem. It is a new breakthrough in the field of characterization of the surface properties of materials by NMR in the liquid. We analyzed the application of acorn surface area analyzer in pharmaceuticals, cosmetic materials, electronic products because acorn surface area analyzer could reflects the important characteristics of the surface properties and structural features of substance. And we provide the prospective of the applications of NMR techniques in organic matter of soils, drug and natural products detecting..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 497 (2015)
Selective Determination of Itraconazole in the Presence of Its Oxidative Degradation Product by A New Spectrophotometric Method
Nesrine T. Lamie
A simple, specific, accurate and precise spectrophotometric stability indicating method is developed for determination of itraconazole in the presence of its oxidative degradation product and in pharmaceutical formulations. A newly developed spectrophotometric method called ratio difference method by measuring the diffA simple, specific, accurate and precise spectrophotometric stability indicating method is developed for determination of itraconazole in the presence of its oxidative degradation product and in pharmaceutical formulations. A newly developed spectrophotometric method called ratio difference method by measuring the difference in amplitudes between 230 and 265 nm of ratio spectra. The calibration curve is linear over the concentration range of 5～25 μg·mL-1 with mean percentage recovery of 99.81±1.002. Selective quantification of itraconazole, singly in bulk form, pharmaceutical formulations and in the presence of its oxidative degradation product is demonstrated. The results have been statistically compared with a pharmacopeial method..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 502 (2015)
Measurement of Atomic Number of Alkali Vapor and Pressure of Buffer Gas Based on Atomic Absorption
ZHENG Hui-jie, QUAN Wei, LIU Xiang, CHEN Yao, and LU Ji-xi
High sensitivitymagnetic measurementscanbe achieved by utilizing atomic spinmanipulation in the spin-exchange-relaxation-free (SERF) regime, which uses an alkali cell as a sensing element. The atomic number density of the alkali vapor and the pressure of the buffer gasare among the most important parameters of the cellHigh sensitivitymagnetic measurementscanbe achieved by utilizing atomic spinmanipulation in the spin-exchange-relaxation-free (SERF) regime, which uses an alkali cell as a sensing element. The atomic number density of the alkali vapor and the pressure of the buffer gasare among the most important parameters of the cell andrequire accurate measurement. A method has been proposed and developedto measure the atomic number density and the pressure based on absorption spectroscopy, by sweeping the absorption line and fittingthe experiment data with a Lorentzian profile to obtainboth parameters. Due to Doppler broadening and pressure broadening, which is mainly dominated by the temperature of the cell and the pressure of buffer gas respectively, this work demonstrates a simulation of the errorbetween the peaks of the Lorentzian profile and the Voigt profile caused by bothfactors. The results indicates that the Doppler broadening contribution is insignificantwith an error less than 0.015% at 313～513 K for a 4He density of 2 amg, and an error of 0.1% in the presence of 0.6～5 amg at 393 K. We conclude that the Doppler broadening could be ignored under above conditions, and that the Lorentzianprofile is suitably applied to fit the absorption spectrumobtainingboth parameters simultaneously. In addition we discuss the resolution and the instability due to thelight source, wavelength and the temperature of the cell. We find that the cell temperature, whose uncertainty is two orders of magnitude larger than the instability of the light source and the wavelength, is one of the main factors which contributes to the error..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 507 (2015)
Characterization of Matrix Effects in Microanalysis of Sulfide Minerals by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry Based on An Element Pair Method
YUAN Ji-hai, ZHAN Xiu-chun, HU Ming-yue, ZHAO Ling-hao, and SUN Dong-yang
Matrix effect between reference materials and samples is one of the major factors affecting the accuracy of analytical results by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). However, there is no method or calculation formula to quantify matrix effect between standards and samples up to dateMatrix effect between reference materials and samples is one of the major factors affecting the accuracy of analytical results by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). However, there is no method or calculation formula to quantify matrix effect between standards and samples up to date. In this paper, the linear correlation coefficient r of the Ii/Iis-ci/cis graphs of element pairs were used to characterize the matrix effect, which took the ratios of concentrations(ci/cis) and intensities(Ii/Iis) of the analytical element and internal standard element as x-axis and y-axis, respectively. Matrix effects of 6 element pairs in 13 glass reference materials, 2 sulfide reference materials and 2 sulfide minerals using Fe as internal standard was studied, with the linear correlation coefficient r of Fe—Cu, Fe—Zn element pairs both less than 0.999 and trace Fe—Mn, Fe—Co, Fe—Ga, Fe—Pb element pairs all better than 0.999. Matrix effects of 3 major element pairs in 2 sulfide reference materials and 6 sulfide minerals using S as internal standard was also studied, with the linear correlation coefficient r of S—Fe, S—Cu, S—Zn all less than 0.999. The great majority of relative errors of EMPA analytical results for major elements in sulfide minerals were greater than 10%, whether analyzed using Fe as internal standard with glass reference materials as external standard, or S as internal standard with sulfide reference materials MASS-1, IMER-1 as external standard, respectively. But the most analytical results for trace elements calibrated by glass reference materials using Fe as internal standard were well agreed with sulfide standard MASS-1, with the relative errors less than 15%. The results showed that matrix effects existed in glass reference materials, sulfide reference materials and sulfide minerals, and it also proved a certain rationality and practicability for quantification of matrix effect using the linear correlation coefficient r of the Ii/Iis-ci/cis graphs by this element pair method. This study also indicated that trace elements in sulfide minerals could be calibrated using Fe as internal standard with non-matrix matched glass reference materials as external standard, especially for NIST610 contained nearly all the trace elements in sulfide minerals and with relative high concentrations of each element, which obtained analytical results agreed well with sulfide standard MASS-1..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 512 (2015)
Analysis of Inorganic Elements in Hydroponic Taraxacum Mongolicum Grown under Different Spectrum Combinations by ICP-AES
CHEN Xiao-li, Morewane M.B, XUE Xu-zhang, GUO Wen-zhong, and WANG Li-chun
Dandelion (Taraxacum mongolicum) was hydroponically cultured in a completely enclosed plant factory, in which fluorescence and LED emitting spectra of different bands were used as the sole light source for plant growth. Effects of spectral component on the growth of dandelion were studied and the contents of ten inorgaDandelion (Taraxacum mongolicum) was hydroponically cultured in a completely enclosed plant factory, in which fluorescence and LED emitting spectra of different bands were used as the sole light source for plant growth. Effects of spectral component on the growth of dandelion were studied and the contents of ten inorganic elements such as K, P, Ca, Mg, Na, Fe, Mn, Zn, Cu and B in dandelion were analyzed by ICP-AES technology. The results showed that: (1) Under the condition of similar photosynthetic active radiation (PAR), single R or combined spectrums of FLRB were beneficial for biomass accumulation, while single B was the contrary;(2) Macroelements content ratio in Taraxacum mongolicum grown under FL was K∶Ca∶P∶Mg∶Na=79.74∶32.39∶24.32∶10.55∶1.00, microelements content ratio was Fe∶Mn∶B∶Zn∶Cu=9.28∶9.71∶3.82∶2.08∶1.00;(3) Red light (peak at 660 nm) could promote the absorptions of Ca, Fe, Mn, Zn, while absorption of Cu was not closely related to spectral conditions;(4) The highest accumulation of Ca, Na, Mn and Zn were obtained in aerial parts of Taraxacum mongolicum plants grown under pure red spectrum R, while the accumulation of the rest six elements reached the highest level under the mixed spectrum FLRB..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 519 (2015)
Standard Addition Determination of Impurities in Na2CrO4 by ICP-AES
WANG Li-ping, FENG Hai-tao, DONG Ya-ping, PENG Jiao-yu, LI Wu, SHI Hai-qin, and WANG Yong
Coupled plasma atomic emission spectrometry (ICP-AES) was used to determine the trace impurities of Ca, Mg, Al, Fe and Si in industrial sodium chromate. Wavelengths of 167.079, 393.366, 259.940, 279.533 and 251.611 nm were selected as analytical lines for the determination of Al, Ca, Fe, Mg and Si, respectively. The anCoupled plasma atomic emission spectrometry (ICP-AES) was used to determine the trace impurities of Ca, Mg, Al, Fe and Si in industrial sodium chromate. Wavelengths of 167.079, 393.366, 259.940, 279.533 and 251.611 nm were selected as analytical lines for the determination of Al, Ca, Fe, Mg and Si, respectively. The analytical errors can be eliminated by adjusting the determined solution with high pure hydrochloric acid. Standard addition method was used to eliminate matrix effects. The linear correlation, detection limit, precision and recovery for the concerned trace impurities have been examined. The effect of standard addition method on the accuracy for the determination under the selected analytical lines has been studied in detail. The results show that the linear correlations of standard curves were very good (R2=0.998 8 to 0.999 6) under the determined conditions. Detection limits of these trace impurities were in the range of 0.013 4 to 0.028 0 mg·L-1. Sample recoveries were within 97.30% to 107.50%, and relative standard deviations were lower than 5.86% for eleven repeated determinations. The detection limits and accuracies established by the experiment can meet the analytical requirements and the analytic procedure was used to determine trace impurities in sodium chromate by ion membrane electrolysis technique successfully. Due to sodium chromate can be changed into sodium dichromate and chromic acid by adding acids, the established method can be further used to monitor trace impurities in these compounds or other hexavalent chromium compounds..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 523 (2015)
Study on the Method for the Determination of Trace Boron, Molybdenum, Silver, Tin and Lead in Geochemical Samples by Direct Current Arc Full Spectrum Direct Reading Atomic Emission Spectroscopy (DC-Arc-AES)
HAO Zhi-hong, YAO Jian-zhen, TANG Rui-ling, ZHANG Xue-mei, LI Wen-ge, and ZHANG Qin
The method for the determination of trace boron, molybdenum, silver, tin and lead in geochemical samples by direct current arc full spectrum direct reading atomic emission spectroscopy (DC-Arc-AES) was established. Direct current arc full spectrum direct reading atomic emission spectrometer with a large area of solid-sThe method for the determination of trace boron, molybdenum, silver, tin and lead in geochemical samples by direct current arc full spectrum direct reading atomic emission spectroscopy (DC-Arc-AES) was established. Direct current arc full spectrum direct reading atomic emission spectrometer with a large area of solid-state detectors has functions of full spectrum direct reading and real-time background correction. The new electrodes and new buffer recipe were proposed in this paper, and have applied for national patent. Suitable analytical line pairs, back ground correcting points of elements and the internal standard method were selected, and Ge was used as internal standard. Multistage currents were selected in the research on current program, and each current set different holding time to ensure that each element has a good signal to noise ratio. Continuous rising current mode selected can effectively eliminate the splash of the sample. Argon as shielding gas can eliminate CN band generating and reduce spectral background, also plays a role in stabilizing the arc, and argon flow 3.5 L·min-1 was selected. Evaporation curve of each element was made, and it was concluded that the evaporation behavior of each element is consistent, and combined with the effects of different spectrographic times on the intensity and background, the spectrographic time of 35s was selected. In this paper, national standards substances were selected as a standard series, and the standard series includes different nature and different content of standard substances which meet the determination of trace boron, molybdenum, silver, tin and lead in geochemical samples. In the optimum experimental conditions, the detection limits for B, Mo, Ag, Sn and Pb are 1.1, 0.09, 0.01, 0.41, and 0.56 μg·g-1 respectively, and the precisions (RSD, n=12) for B, Mo, Ag, Sn and Pb are 4.57%～7.63%, 5.14%～7.75%, 5.48%～12.30%, 3.97%～10.46%, and 4.26%～9.21% respectively. The analytical accuracy was validated by national standards and the results are in agreement with certified values. The method is simple, rapid, is an advanced analytical method for the determination of trace amounts of geochemical samples’ boron, molybdenum, silver, tin and lead, and has a certain practicality..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 527 (2015)
Application of Tessier-AAS to the Non-Biological Transformation Mechanism of Chemical Speciation of Lead in Red Soil in Agricultural Area of Central China
FAN Chun-hui, ZHANG Ying-chao, and WANG Jia-hong
The soil contamination of heavy metals, from the areas of mine, highway, industrial area, agricultural land and so on, is nowadays a serious issue all over the world. The contamination of heavy metals in large agricultural area might lead to the decrease of products quality and economic value. Actually, the accumulatioThe soil contamination of heavy metals, from the areas of mine, highway, industrial area, agricultural land and so on, is nowadays a serious issue all over the world. The contamination of heavy metals in large agricultural area might lead to the decrease of products quality and economic value. Actually, the accumulation amount of heavy metals by crops is much more related to the activated speciation, which is exchangeable and able to transform to the forms of carbonates, Fe-Mn oxides, organic matter and residual. Thus, the investigation to reveal the transformation mechanism of heavy metals caused by soil conditions might be appropriate to reduce the contaminated risk to crops. The vermicular red soil from the agricultural area of central China was used as sample in the paper, and the Tessier Sequential Extraction Procedure-atomic absorption spectroscopy (AAS) was applied to discuss the chemical speciation and non-biological transformation mechanism of Pb at different conditions. The results showed: the total amount of Pb is 32.56 mg·kg-1, lower than the first level of the State Environmental Quality Standard for Soils. The Pb content of different speciation, with decreased concentration, is residual (54.55% of total Pb content), bound to Fe-Mn oxides, bound to organic matter, bound to carbonates and exchangeable. The pH value of red soil is related to the charge amount on surface of inorganic colloids and organic matter, and the water content of red soil would change the redox potential, effective for the variation of chemical speciation of Pb. The environmental factors of straw dosage and aging time could change Pb speciation, with Pb concentration of residual form the highest. The Muller Index of Igeo is 0.302 5, indicating the contribution of human activities. The Tessier Sequential Extraction Procedure-AAS is effective for the non-biological transformation mechanism identification of Pb speciation in red soil..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 534 (2015)
Preparation of Polyacrylonitrile/Natural Sand Composite Materials and Analysis of Adsorption Properties of Pb(Ⅱ) on It by FAAS
Medine Abduwayit, Ismayil Nurulla, and Shawket Abliz
Surfaces of natural sand particles were modified with (3-chloropropyl) trichlorosilane, so that bridging groups were introduced on the surfaces of natural sand particles;By grafting polyacrylonitrile onto the modified surfaces of the natural sand particles, a novel polyacrylonitrile/natural sand composite material was Surfaces of natural sand particles were modified with (3-chloropropyl) trichlorosilane, so that bridging groups were introduced on the surfaces of natural sand particles;By grafting polyacrylonitrile onto the modified surfaces of the natural sand particles, a novel polyacrylonitrile/natural sand composite material was prepared from the acrylonitrile, the azobisisobutyronitrile, the divinylbenzene and the modified natural sand particles, which are as functional monomer, initiator, either skeleton monomer or cross-linking agent and carrier respectively;the composite materials were characterized by using infrared spectroscopy and scanning electron microscopy;On the FTIR spectrum, the main characteristic peaks of various functional groups including nitrile,benzene ring,and silicon hydroxyl, which were from functional monomer, cross-linking agent and carrier respectively, were observed. On the SEM, two different cross section morphologies having different density which were from acrylonitrile and modified sand particles were observed;This proved that the polyacrylonitrile was decorated on modified sand particles during our preparation process. After preparing the composite materials, micro-column of separation and preconcentration was prepared using the composite materials as filler;the adsorption of some toxic heavy metal ions onto the composite materials was observed by flame atomic absorption spectrometry (FAAS);The results show that the adsorption of Pb2+ onto the composite materials was more stronger than the absorption of other toxic heavy metal ions, therefore, in this paper, the adsorption of Pb2+ onto the composite materials was mainly studied,at room temperature, when pH and flow rate of solution were 5.4 and 4 mL·min-1 respectively, the trace Pb(Ⅱ) ions could be quantitatively adsorbed onto the composite materials;the maximum adsorption capacity of Pb(Ⅱ) on the composite materials can reach 62.9 mg·g-1. the column was eluted by 0.5 mol·L-1 HCl and recovery of Pb(Ⅱ) was more than 96%..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 539 (2015)
Analysis of XPS in the Removal of Se(Ⅳ) from Groundwater with Pyrite
LIU Hong-fang, QIAN Tian-wei, and ZHANG Min-gang
Selenium (Se) is an elementary trace nutrient element for human but there is a very narrow range between deficit and toxic levels. Furthermore, excessive intake of Selenium is harmful for human. The product species of selenite which was removal by pyrite particles was studied in the present research. In the experimentsSelenium (Se) is an elementary trace nutrient element for human but there is a very narrow range between deficit and toxic levels. Furthermore, excessive intake of Selenium is harmful for human. The product species of selenite which was removal by pyrite particles was studied in the present research. In the experiments, the pyrite particles were prepared by the wet ball mill method, and surface analyses of pyrite before and after contact with Se(IV) were conducted using X-ray photoelectron spectroscopy (XPS). Besides, the prepared pyrite samples were also characterized using both X-ray diffraction (XRD) and scanning electron microscope (SEM). X-ray diffraction analysis indicated that the purity of the prepared pyrite particles was above 97%, and the characteristic diffraction peaks of the particles well matched with that of FeS2 crystalline. Scanning electron microscope determination showed the shape of the particles was approximate ball and the size was range from 80 to 180 nm. And thus the pyrite particles prepared by the wet ball mill method had less particle size, larger specific surface area and higher reactive ability. The batch experiments exhibited the pyrite particles were able to remove 95% of Se(Ⅳ) (20 mg·L-1) from water within 12 hours. And the kinetic tests indicated reaction process between pyrite and Se(Ⅳ)fits a pseudo-first order kinetic model, which gives a pseudo-first order rate constant(kobs) of 0.26 h-1. XPS analyses were using the XPSPEAK program which has a Gaussian Lorentzian function. The results clearly displays that Se(Ⅳ) prefer to react with the surface-bound S2-2 rather than reacted with the surface-bound Fe2+ of pyrite particles. From XPS graph, it can be seen that the binding energy of sulfur element and iron element composed of pyrite shifted to the left a little, which means expensive state of sulfur element and iron element appeared on the pyrite surface. Analysis of the oxidation state of Se on the surface of pyrite particles by X-ray photoelectron spectra showed evidence for the reduction of Se(Ⅵ) to insoluble element Se(0) species. Besides, a spot of Se(Ⅳ)was existence on the surface of pyrite particles. The calculation results displayed that zero-valent selenium was dominant. At that, redox reaction was the main process when removal of Se(Ⅳ)in aqueous environment with pyrite, along with sorption reaction at the same time. The results of removal of Se (Ⅳ) in groundwater using pyrite offer important theoretical value and practical significance..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 543 (2015)
The Validation of the Effect of Correcting Spectral Background Changes Based on Floating Reference Method by Simulation
WANG Zhu-lou, ZHANG Wan-jie, LI Chen-xi, CHEN Wen-liang*, and XU Ke-xin
There are some challenges in near-infrared non-invasive blood glucose measurement, such as the low signal to noise ratio of instrument, the unstable measurement conditions, the unpredictable and irregular changes of the measured object, and etc. Therefore, it is difficult to extract the information of blood glucose conThere are some challenges in near-infrared non-invasive blood glucose measurement, such as the low signal to noise ratio of instrument, the unstable measurement conditions, the unpredictable and irregular changes of the measured object, and etc. Therefore, it is difficult to extract the information of blood glucose concentrations from the complicated signals accurately. Reference measurement method is usually considered to be used to eliminate the effect of background changes. But there is no reference substance which changes synchronously with the anylate. After many years of research, our research group has proposed the floating reference method, which is succeeded in eliminating the spectral effects induced by the instrument drifts and the measured object’s background variations. But our studies indicate that the reference-point will changes following the changing of measurement location and wavelength. Therefore, the effects of floating reference method should be verified comprehensively. In this paper, keeping things simple, the Monte Carlo simulation employing Intralipid solution with the concentrations of 5% and 10% is performed to verify the effect of floating reference method used into eliminating the consequences of the light source drift. And the light source drift is introduced through varying the incident photon number. The effectiveness of the floating reference method with corresponding reference-points at different wavelengths in eliminating the variations of the light source drift is estimated. The comparison of the prediction abilities of the calibration models with and without using this method shows that the RMSEPs of the method are decreased by about 98.57%(5%Intralipid)and 99.36%(10%Intralipid)for different Intralipid. The results indicate that the floating reference method has obvious effect in eliminating the background changes..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 547 (2015)
A Simple Design of Functional Near-Infrared Spectroscopy System
XU Gang, LI Xiao-li, and LIU Xiao-min
With the development in last twenty years, functional near-infrared spectroscopy (fNIRS) is a non-invasive brain imaging technique which widely used in cognitive neuroscience studies. Based on mechanism of neurovascular coupling, increased functional neural activities in brain induce higher regional cerebral blood flowWith the development in last twenty years, functional near-infrared spectroscopy (fNIRS) is a non-invasive brain imaging technique which widely used in cognitive neuroscience studies. Based on mechanism of neurovascular coupling, increased functional neural activities in brain induce higher regional cerebral blood flow, which will cause relative concentration change of oxygenated and deoxygenated hemoglobin. In this paper, a single channel continuous wave fNIRS system based on multi-function data acquisition board was proposed. With the benefits of narrow spectral peaks and low divergence, laser diodes provided a better accuracy for measurement with optimal dual-wavelength of 690 and 830 nm. Frequency multiplexing technique was used to distinguish light sources from different emitters, and remove environmental stable interference sources such as ambient light and line power noise as well. LabVIEW was used to design graphical user interface with functionalities including source sequence schedule, auto gain setting, digital in-phase and quadrature demodulation, data visualization and storage. The experimental results during holding breath and mental arithmetic task indicated that our system was capable of monitoring regional concentration change of hemoglobin in real time, and detecting activation associated with advanced brain functions..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 552 (2015)
The Linear Hyperspectral Camera Rotating Scan Imaging Geometric Correction Based on the Precise Spectral Sampling
WANG Shu-min, ZHANG Ai-wu, HU Shao-xing, WANG Jing-meng, MENG Xian-gang, DUAN Yi-hao, and SUN Wei-dong
As the rotation speed of ground based hyperspectral imaging system is too fast in the image collection process, which exceeds the speed limitation, there is data missed in the rectified image, it shows as the black lines. At the same time, there is serious distortion in the collected raw images, which effects the featuAs the rotation speed of ground based hyperspectral imaging system is too fast in the image collection process, which exceeds the speed limitation, there is data missed in the rectified image, it shows as the black lines. At the same time, there is serious distortion in the collected raw images, which effects the feature information classification and identification. To solve these problems, in this paper, we introduce the each component of the ground based hyperspectral imaging system at first, and give the general process of data collection. The rotation speed is controlled in data collection process, according to the image cover area of each frame and the image collection speed of the ground based hyperspectral imaging system, And then the spatial orientation model is deduced in detail combining with the star scanning angle, stop scanning angle and the minimum distance between the sensor and the scanned object etc. The oriented image is divided into grids and resampled with new spectral. The general flow of distortion image corrected is presented in this paper. Since the image spatial resolution is different between the adjacent frames, and in order to keep the highest image resolution of corrected image, the minimum ground sampling distance is employed as the grid unit to divide the geo-referenced image. Taking the spectral distortion into account caused by direct sampling method when the new uniform grids and the old uneven grids are superimposed to take the pixel value, the precise spectral sampling method based on the position distribution is proposed. The distortion image collected in Lao Si Cheng ruin which is in the Zhang Jiajie town Hunan province is corrected through the algorithm proposed on above. The features keep the original geometric characteristics. It verifies the validity of the algorithm. And we extract the spectral of different features to compute the correlation coefficient. The results show that the improved spectral sampling method is better than the direct sampling method. It provides the reference for the similar product used on the ground..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 557 (2015)
A High Sensitivity Micro-Ring Humidity Sensor Based on U-Shaped Waveguide Coupled Single Micro-Ring Structure
LI Zhi-quan, WANG Lu-na, LI Xin, and ZHANG Xin
The paper proposes a novel high sensitivity humidity sensor based on a U-shaped waveguide-coupled single micro-ring, Polyimide is used as the wet material, the refractive index of humidity-sensing part changes as relative humidity changes, thus leading to a obvious peak drift. The transfer function of the structure is The paper proposes a novel high sensitivity humidity sensor based on a U-shaped waveguide-coupled single micro-ring, Polyimide is used as the wet material, the refractive index of humidity-sensing part changes as relative humidity changes, thus leading to a obvious peak drift. The transfer function of the structure is derived basing on transfer matrix method and the paper mainly discusses the influence on the output spectrum with different humidity-sensing parts. Through the theoretical simulation of Matlab, the whole structure of U-shaped waveguide coupled single micro-ring is proved to be the best humidity-sensing part. The free spectral range (FSR) will be doubled compared to the traditional single micro ring structure while the length between the two coupling points of the U-shaped waveguide is an integer multiple of circumference of the micro-ring. When the relative humidity of external environment changes from 10%RH to 100%RH, the output spectrum appears a obvious drift from 0.027 to 0.191 μm and the sensitivity reaches up to 0.001 8 μm/%RH. Compared to FBG humidity sensor with high sensitivity, the sensitivity in this article is increased by 10 to 100 times, achieving a high sensitivity in the sense of humidity when the wide range of filter frequency selection is taken into account..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 563 (2015)
Design and Analysis of a Novel Light Visible Spectrum Imaging Spectrograph Optical System
SHEN Man-de, LI Fei, ZHOU Li-bing, LI Cheng, REN Huan-huan, and JIANG Qing-xiu
A novel visible spectrum imaging spectrograph optical system was proposed based on the negative dispersion, the arbitrary phase modulation characteristics of diffractive optical element and the aberration correction characteristics of freeform optical element. The double agglutination lens was substituted by a hybrid rA novel visible spectrum imaging spectrograph optical system was proposed based on the negative dispersion, the arbitrary phase modulation characteristics of diffractive optical element and the aberration correction characteristics of freeform optical element. The double agglutination lens was substituted by a hybrid refractive/ diffractive lens based on the negative dispersion of diffractive optical element. Two freeform optical elements were used in order to correct some aberration based on the aberration correction characteristics of freeform optical element. An example and frondose design process were presented. When the design parameters were uniform, compared with the traditional system, the novel visible spectrum imaging spectrograph optical system's weight was reduced by 22.9％, the total length was reduced by 26.6%, the maximal diameter was reduced by 30.6%, and the modulation transfer function (MTF) in 1.0 field-of-view was improved by 0.35 with field-of view improved maximally. The maximal distortion was reduced by 1.6%, the maximal longitudinal aberration was reduced by 56.4%, and the lateral color aberration was reduced by 59.3%. From these data, we know that the performance of the novel system was advanced quickly and it could be used to put forward a new idea for modern visible spectrum imaging spectrograph optical system design..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 568 (2015)
[in Chinese]
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 1 (2015)
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