The process of the radiation temperature measurement data is to understand the relationship between the spectral emissivity and the true temperature. If the spectral emissivity model is not in conformity with the actual spectral emissivity model, the large temperature measurement error will be occured. Therefore, it is one of the main problems to be solved in this field in terms of how to reduce the dependence of the spectral emissivity and the true temperature on the measurement model. The paper puts forward an algorithm, which can find out the spectral emissivity and the true temperature without the assumption of the model relationship between the emissivity and wavelength. Through simulation and experiment, the results show that this algorithm can be used to solve a relatively reasonable spectral emissivity and meet the requirements of a certain precision of true temperature.The algorithm has the features of being simple, reliable, universal, and suitable for spectral measurement of emissivity and the true temperature.

Polarization parameters indirect microscopic imaging, which utilizes conventional microscope as a basic light path and inserts modulations into the light path, finally, the inversion images are obtained after fitting and filtering the data obtained from the system. By analyzing the near-field spatial spectra scattering around nanoparticles to solve spatial spectra scattering. Comparing polarization parameters indirect microscopic imaging with direct imaging by using FDTD modeling, it can be found that the resolution of polarization parameters indirect microscopic imaging is much higher than conventional imaging and it can not only detect the shape and electric field distribution of nanoparticles, but also obtain much wider spatial scattering spectra.

Based on the needs of rapid on-line monitoring of bacteria microorganism in water, a multi-wavelength transmission spectrum measurement system was set up. Ultraviolet transmission spectra of potassium dichromate standard solution and visible transmission spectra of neutral filter were measured by the experiment system, which were then compared with the transmission spectra measured by ultraviolet and visible spectrophotometer to validate the accuracy of the transmission spectra measured by the experiment system. Staphylococcus aureus which commonly existed in water was studied in this paper. Moreover, small angle transmission spectra of staphylococcus aureus were measured over a broad range of transmission wavelength (220~900 nm) by the experiment system. The results confirmed the accuracy and rapidity of the experiment system measuring the transmission spectra of bacteria microorganism. The transmission spectra of the potassium dichromate standard solution or neutral filter measured by the experiment system was strongly correlated with the transmission spectra measured by Ultraviolet and visible spectrophotometer, and their linear fitting coefficients were 0.999 7 and 0.999 5 (R2=0.999 7 and R2=0.999 5). The errors of optical densities measured by the experiment system were less than 5.00% and 4.58%, which showed that spectral consistency was better and ultraviolet and visible transmission spectra of standard samples measured by the experiment system had a high accuracy. The correlation coefficient of transmission spectra of the staphylococcus aureus measured by the experiment system after calibration fitted with that of ultraviolet and visible spectrophotometer is 0.999 97. As well, the error was less than 0.74% between the experimental system and ultraviolet and visible spectrophotometer. In addition, single measurement time of the average transmission spectrum measured by the system was 15s, which was 30 times of the signal acquisition. It showes that the experimental system can quickly and accurately obtain the multi-wavelength transmission spectra of bacterial microbial in water with respect to ultraviolet-visible spectrophotometer. The transmission spectrum measured by the experimental system is not only highly accurate, but also shortens the spectrum measurement time, which provides a technical support for the rapid detection of bacterial microbial in water.

Acetylene is a kind of fault gases used to judge the operating state of transformer, and its concentration reflects the operation condition, so the detection of acetylene concentration has important significance in transformer maintenance. In order to detect acetylene concentration generated in the running process accurately to provide technical parameters for transformer maintenance, this paper has done a research based on the DFB laser photoacoustic spectroscopy for trace acetylene detection, which improves traditional photoacoustic spectroscopy detection system. The intensity of photoacoustic signal is proportional to the incident laser power based on photoacoustic theory, so in this paper a reflector was installed opposite the light-emitting window of the photoacoustic cell to reflect infrared light back to increase the power of incident light, which can enhance the intensity of photoacoustic signal and then further improve the detection sensitivity of the photoacoustic detection system. The photoacoustic spectroscopy detection system will have the optimal detection performance under the optimal modulation frequency and modulation depth, so in this paper the important parameters of optimal modulation frequency and modulation depth were studied. Through the intensity of photoacoustic signal of a certain concentration of acetylene gas under different modulation frequencies and modulation depths, the optimal modulation frequency and optimal modulation depth of the system were determined as 767 Hz and 0.3 mV. Before the detection of unknown concentration of acetylene gas, the photoacoustic detection system was calibrated by different concentrations of acetylene gas. The photoacoustic signal and gas concentrations were fitted by the least squares, which had a good linearity. The stability of the system was evaluated by Allan variance, which clearly showed that the system reached the minimum detection concentration using the average time of 200 s. The experiments show that the minimum detection limit of the system is 0.3 μL·L-1 under the atmospheric pressure with a integration time of 10ms. In this paper, the wavelet denoising technique was used for low concentration acetylene gas photoacoustic signal processing, which showed that the noise was effectively eliminated and the signal-to-noise ratio was improved. The resonant photoacoustic spectroscopy detection system designed in this paper has the advantage of easy operation and conforming the lowest detection concentration to the national standard in the detection of acetylene gas for transformer maintenance, which has a broad application prospect in the field of transformer maintenance.

For a long time, the United States and other military powers have been committed to develop their space situational awareness (SSA). The monitoring system of ground space target is an important part of the space situational awareness. Monitoring and identifying of space targets are mainly due to a large number of space debris make the main body of the satellite face some unknown risks. To avoid the space junk and enhance the ability of the satellite identifying the space objects, it is very important to ensure safety of the spacecraft in orbit. In the observation of space debris, because of the compact structure, complex material, and spatial resolution of ground observation equipments, a variety of materials are in the same pixel usually, namely “mixed pixel”. The current researches on mixed pixel mainly focus on obtaining pure components of mixed pixels and the corresponding abundance, but they often neglect that hyperspectral data for determining the number of pure substances is very important for mixed pixels without any prior information analysis. If the estimated number is too small, the extracted endmembers are still mixed pixels; if the number of endmembers is too large, the extracted endmembers may still contain noise components. Based on the spectral linear mixture model, this paper proposes an improved p norm pure pixel identification algorithm. The method is mainly based on the characteristics of spectral data which are similar with those of low dimensional manifolds. Firstly, according to the principle of orthogonal projection, the extracted endmembers are extended to the orthogonal projection operator. By analyzing the p norm of each projected pixel vector, the number of the p norm value higher than the threshold in the vectors is considered to be the number of pure materials. The simulation experiments are carried out by using the commonly used space materials data and the United State Geological Survey database. The experimental results show that the proposed method can not only estimate the number of pure materials, but also extract spectra of the pure materials in the target, which improves the automation of spectral unmixing process to a certain extent. Compared with some existing algorithms, this method has strong robustness and can estimate the correct number of space debris in the case of low SNR. Therefore, the proposed algorithm can greatly improve the feasibility in determining the type and number of materials according to the space debris spectrum.

OH radicals in atmosphere, an important mediator of the photochemical reactions between various atmospheric compositions, play a key role in the formation and transformation of other atmospheric components. Based on the OH concentration spatiotemporal database constructed by MLS global observation results of OH, and the OH emission spectra database from Lifbase, SCIATRAN was modified according to the radiation transmission theory. The simulated image of spatial heterodyne spectrum (SHS) detector was obtained in the state of limb scanning and the contribution of atmospheric OH radical fluorescence emission in observing energy was extracted. Based on the radiation transmission theory, the quantitative influence of the uncertainty of each parameter in the simulation process was analyzed quantitatively. The results can not only provide scientific theoretical supports for the construction of detector for mesospheric OH radical, but also provide the basis for the design of relevant parameters of detector.

Three kinds of new plasma emission patterns were obtained in the mixture of argon and air by using the dielectric barrier discharge device with H shaped gas gap. Compared with the traditional plasma emission patterns, the three kinds of plasma emission patterns are generated in the single and double gas layer gaps. By observing the images of the plasma emission patterns taken by a camera, the micro discharge channels of the single gas layer gap and the double gas layer gap are different in luminous brightness, color and discharge area, which indicates that the plasma parameters of the micro discharge channel may be different. Based on the analysis of three kinds of plasma emission patterns, the plasma parameters of the micro discharge channel in the single and double gas layer gaps were investigated by using the emission spectrum method for the first time. The emission spectra of the N2 second positive band (C3Πu→B3Πg) was collected to calculate the molecule vibration temperature. Furthermore, the broadening of spectral line 696.57 nm (2P2→1S5) was used to estimate the electron densities. The results show that the molecular vibration temperatures of couple filaments in the double gas layer gap with the same thickness are almost the same, and the electron densities are also consistent. The molecular vibration temperature of filaments in the single gas layer gap is higher than that of filaments in the double gas layer gap. The electron densities of filaments in the single gas layer gap are lower than that of filaments in the double gas layer gap. The differences of the plasma parameters of different micro discharge plasma channels in the single gas layer gap and the double gas layer gap can lead to the forming of plasma photonic crystals with various refractive indices, and its periodic arrangement gives it more abundant band gap structures.

Two kinds of rhombus patterns consisted of the bright spot and dim spot were firstly observed and investigated in discharge of gas mixture of air and argon by using the dielectric barrier discharge device with double water electrodes. It was found that dim spot was at the center of four surrounding bright spots in the first kind of rhombus pattern (named rhombus pattern Ⅰ) and the dim spot is at the geometric gravity center of three surrounding bright spots in the second kind of rhombus pattern (named rhombus patternⅡ) by observing the discharge images. The optical emission spectrum method was used to study the several plasma parameters of two kinds of rhombus patterns. The emission spectra of the N2 second positive band（C3Πu→B3Πg） were measured, and the molecule vibration temperature was calculated by the emission intensities. The broadening of spectral line 696.54 nm（2P2→1S5）was used to study the electron densities. The experiment results show that the molecule vibration temperature of the dim spot is higher than that of the bright spot in the two kinds of rhombus patterns, and the molecule vibration temperature and electron densities of the bright spot and dim spot both increase from rhombus patternⅠ to rhombus patternⅡ, while the electron density of the dim spot is lower than that of the bright spot in the rhombus patternⅠ and the electron densities are almost equal in the rhombus patternⅡ. Because the electron densities presents different change trends in two kinds of rhombus patterns, so the short-exposure images were recorded by a high speed video camera and the results show that the dim spot resulting from the volume discharge and surface discharge co-exist in the rhombus patternⅡ. Further study of the electron densities of bright spot of three kinds of patterns found that the hightest was the prepattern of the rhombus patternⅡ and the lowest was the rhombus patternⅡ. These results are of great importance to the formation of the patterns in dielectric barrier discharge.

An analytical formula is derived from conventional expression of transition spectra containing higher terms rovibrational spectral constants Lv based on the difference converging method (DCM), which can calculate the accurate P-branch spectral lines of rovibrational transitions in some diatomic molecules systems. Based on the DCM method, a group of eleven known experimental transition lines is needed and a set of expansion coefficients C is chosen to predict correct transitional spectra of high-lying rovibrational states for a P-branch transition band of a diatomic system. In this study, the transitional spectral lines of high-lying excited states which may not be available experimentally and the rotational spectral constants of the corresponding transition bands were obtained correctly by using the DCM method for the (3, 7) band of A2Πu-X2Πg(Ω=1/2) transiton of the 35Cl+2 and 35Cl37Cl+2 ions. The calculated data can provide a better reference for the further understanding of the internal structure and physical and chemical properties of electronic states of the Cl+2 ion.

Animal glue and egg white are important proteinaceous binding media of ancient polychromy artworks, and the research of their structural changes caused by light aging is highly related to the exploration of pathological changes mechanism as well as the selection of scientific materials and proper conservative methods. Regarding the animal glues (bone, rabbit skin, sturgeon) and egg white in Kunsthistorisches Museum Vienna as the study objects, this paper aimed at studying the protein secondary structure changes after light aging by Fourier transform infrared spectroscopy (FTIR) with the help of deconvolved Amide I and Gaussian fitting method. Results illustrated that the four binders still possessed the typical FTIR spectra characteristics after light aging in spite of some peaks shift, among which glycosidic bond in egg white showed an obvious blue shift. Moreover, deconvolved Amide I and Gaussian fitting results indicated that the contents of α-helix, parallel β-sheets, anti-parallel β-sheets, β-turns and random coils of each binder varied after the light aging. To be specific, α-helix’s content of the bone decreased 22.24% but random coils increased 9.76%, which deduced the uncoiling of the α-helix caused by light. The α-helix’s contents of the rabbit skin and sturgeon reduced 5.31% and 4. 15% respectively, and random coils content of the former showed the minimum growth (6.96%) while that of the latter decreased. Thus, these two were supposed to be of high stability versus light. Egg white showed the poorest light stability due to the highest reduction of α-helix (44.45%) and obvious rise of random coils (27.49%). In addition, the anti-parallel β-sheets’ contents of all the binders increased while the β-turns kept stable. Parallel β-sheets showed a decline trend among all the binders except the sturgeon glue. This research confirmed the feasibility of studying the proteinaceous binders’ secondary structure changes by deconvolved Amide I, Gaussian fitting method and FTIR spectroscopy, which was proved to be a promising method in studying the aging phenomenon of the proteinaceous binders in artworks. However, the transformation mechanism needs further explorations.

Firstly, the source of potassium atoms in solid rocket engine exhaust plume and its radiation mechanism were introduced, and the spectrum of the potassium resonance doublet shape was analyzed based on the theory of atomic spectra. Secondly, the numerical simulation of the plume flow field distribution was carried out with the ideal jet model and the semi-empirical formula. The radiation spectral characteristics of potassium resonance doublet shape from rocket plume were calculated by using the C-G approximation method. Finally, the spectral characteristics of potassium resonance doublet shape signal in the wake of the plume were calculated by using the atmospheric radiative transfer model. The results demonstrate that this method can effectively simulate the fine structure of the NIR spectrum of exhaust plume. The simulation results also show that the signal energy of potassium resonance doublet spectrum can be effectively transmitted through atmosphere, which can be used as the basis for the detection and identification of exhaust plume.

The spectroscopy sensing technology of water COD is an important development direction of modern environmental monitoring. Compared with traditional analytical methods, spectroscopy has more obvious advantages, such as continuous monitoring, online monitoring and fast testing, which is suitable for fixed-point and real-time monitoring of environmental water samples for COD. In this study, the ultraviolet absorption spectrum and the near infrared spectrum of real water samples were collected respectively by ultraviolet absorption spectrometry and near infrared transmission method. The COD prediction model was established by utilizing different spectral pretreatment methods combined with partial least squares regression(PLS) and multiple linear regression(MLR), and then the quantitative prediction and model parameters of ultraviolet and near infrared spectra measurement for COD were analyzed, finding that the Savitzky-Golay (SG) smoothing partial least-squares model had good prediction. Through comparison, the determination coefficients of prediction were 0.992 1 and 0.987 7, respectively, and RMSEP were 10.438 6 and 5.972 0, respectively. Ultraviolet and Near-infrared spectroscopy combined with MLR analysis model had poor prediction, with the determination coefficients of prediction 0.928 0 and 0.957 3, respectively. Through a comprehensive analysis of the experimental results, ultraviolet absorption spectrum prediction model in 280～310 nm spectral region had a good performance. Near infrared spectral spectrum model had the best performance in 7 250～6 870 cm-1 spectral region. Ultraviolet spectrum corresponding to the decision of prediction model was higher, but the near spectrum model had better stability and repeatability. Studies show that the spectrum sensing technology can be used in the quantitative predicted analysis of COD in actual water. The conclusion from the paper laid a theoretical basis for the development of portable water testing equipments.

Fourier transform infrared (FTIR) spectroscopy was used to establish a rapid method for the identification of species of bolete mushrooms and content prediction of cadmium (Cd). The information of infrared spectra based on 98 fruiting bodies of 11 species of bolete mushrooms were collected and analyzed. The original infrared spectra were optimized by first derivative, standard normal variate (SNV) and multiplicative signal correction (MSC), and then identification of different species of bolete mushrooms was performed by partial least squares discriminant analysis (PLS-DA). The Cd contents were determined by inductively coupled plasma emission spectrometer (ICP-AES) and the accumulation regularity for Cd was analyzed in order to evaluate the food safety of boletes according to Chinese national food safety standards and limit contaminants in food (GB 2762—2012). Based on the accumulation mechanism of Cd in edible mushrooms, the infrared spectral and Cd content data of tested samples were integrated and PLS model was used to rapidly predict the Cd content in boletes. The results showed that: (1) The spectral data were analyzed by PLS-DA after appropriate pretreatments, and the cumulative contribution rate of the first three principal components was 79.3% as well as all the samples could be correctly classified according to the species in the three-dimensional score plot. (2) There were obvious differences in the accumulation of Cd contents in different samples and the Cd contents in the bolete mushrooms were ranged from 0.05 to 23.41 mg·kg-1 dw. In addition, there were some health risks for eating the mushrooms because Cd contents in most samples were higher than the standard GB 2762—2012 except the mushrooms collected from Wuhua district in Kunming. (3) The integrated data of the infrared spectra and Cd content were optimized by orthogonal signal correction-wavelet compression (OSCW) and the prediction of Cd content in boletes was performed by PLS model. The R2 of the training set and validation set were 0.851 9 and 0.882 4, respectively, while RMSEE and RMSEP were 2.59 and 2.67, respectively. The predictive values of Cd content in most boletes were approximate to the measured values which indicated that the model could be used for rapid prediction of Cd content in boletes. FTIR combined with chemometrics could be proposed to rapidly discriminate the species of bolete mushrooms and predict Cd content accurately. This study can provide a rapid and effective method for quality control and identification of wild-grown bolete mushrooms.

Marine environmental pollution in China has become increasingly serious with most pollution being caused by inorganic nitrogen and phosphate. An efficient monitoring and fast measurement of oceanic nutritive salts, especially nitrate salt, has gained greater significance . The traditional detection methods, mostly utilizing analytic chemistry, tend to be more suitable for laboratory testing. Infrared absorption spectrum is important for real-time monitoring of marine nutrients, since it not only makes up for the shortcomings of traditional methods, but also provides fast and simultaneous monitoring of various nutrients at the same time. However, marine nutrient concentrations in seawater are at particularly low level. As a result, normal IR detection is difficult to meet the requirements due to the limitation . This paper aims to utilize surface enhanced infrared absorption effect (SEIRA) of nanomaterials, making the detection of ocean nutrients with IR adsorption possible.Surface-enhanced infrared absorption (SEIRA) of nano-materials is expected to improve dramatically the sensitivity of traditional FTIR and positively achieve the goal of swift measurement of oceanic nutritive salts. Nano silver (Ag) has remarkable surface plasmon resonance effect that could help achieve high SEIRA. Diamond with extraordinarily strong anti-corrosion property is suitable for infrared window.In this paper, silver/diamond powder (Ag/DP) composites were prepared via pyrolysis of silver nitrate (AgNO3) on silicon substrate. Proportion of Ag and DP (nAg∶nC) on the IR adsorption of NaNO3 solution was investigated. Our results showed that Ag/DP composites significantly increased the IR adsorption of two individual antisymmetric stretching mods of NO-3. When nAg∶nC was 2∶1, Ag/DP composites indicated the strongest enhancement of IR adsorption of NaNO3 solution. This paper will be an important contribution for real-time, long-term and continuous testing of marine nutrients. It will also provide important data support for marine disaster prevention, marine pollution control and other areas of the marine environment management.

The method of identifying maize seed purity by analysising seeds spectral images of a small amount of near infrared bands was developed to satisfy the needs of rapid inspection and automatic sorting of maize hybrid seeds. The spectral images of hybrid and female parent of 5 maize varieties at 4 short wave near infrared bands in transmission mode and 4 medium wave near infrared bands in reflection mode were collected. Black-white calibration, median filtering, otsu method were applied to remove the noise and extract the seeds from background. Texture features were extracted by histogram statistics(HS) and gray level co-occurrence Matrix(GLCM). Splicing the feature data at each wavelength, principal component analysis(PCA) and orthogonal linear discriminant analysis(OLDA) were applied to reduce dimensions and obtain the best separability of subspace. The transmission and reflection spectral image purity identification model was built by support vector machine (SVM). The average correct identification rate of 5 maize varieties was above 85% both in transmission and reflection models. This research show that it is feasible to use spectral images of a small amount of near infrared bands to identify the purity of maize hybrid seeds.

Beef is highly susceptible to microbial infection causing spoilage in the process of transportation, so the monitoring on beef spoilage is very important. This paper proved that beef in the process of spoilage released ammonia and carbon dioxide which were the main volatile substances. We used the long optical path FTIR spectra to detect the volatiles of beef spoilage. We quantitatively analyzed the change rule of ammonia and carbon dioxide in the process of beef spoilage to judge the state of beef. We used principal component analysis(PCA) to realize infrared spectral classification of volatile substance and accurately distinguish fresh and decayed beef. We used chemometrics methods: soft independent modeling cluster analysis(SIMCA) and partial least squares discriminant analysis(PLS-DA) to classify the characteristic spectrum of volatiles. The two methods both worked well. Results showed that the long optical path FTIR combined with chemometrics methods could distinguish fresh and decayed beef.

The judgment of base liquor grades is of vital importance in quality control, it’s also an important basis for liquor classified storage and blending. At present, the grades of base liquor are identified by the artificial sensory evaluation of liquor assessment professionals combined with the determination of the main esters by gas chromatography based on the preliminary classification of the workers in workshop according to their experience. However, the artificial sensory evaluation and gas chromatography are cumbersome and time-consuming, which cannot provide real-time information and rapid detection. In recent years, infrared spectroscopy has been widely used in the field of food identification because of its quick analysis, nondestructive testing, high sensitivity and good reproducibility. In this paper, the Fourier transform infrared (FTIR) spectroscopy method combined with attenuated total reflectance (ATR) were applied for the effective qualitative and quantitative analysis of base liquor. FTIR-ATR spectrum in the mid-IR region was used for classifying different grades of base liquor and quantitative analysis of the main esters combined with chemometrics. The results showed that the FTIR-ATR combined with liner discriminant analysis (LDA) could distinguish four different grades of base liquor. The accuracy of the training set and test set both were 100%. The FTIR-ATR combined with back propagation artificial neural network (BPANN) could also achieve an accurate determination of different grades of base liquor effectively, and the correct recognition rate of the training set and test set both were over 95%. The results showed a comparatively good recognition performance of the two methods. The FTIR-ATR combined with synergy interval partial least squares (siPLS) models for predicting the content of the ester compounds were realized with good results. The correlation coefficients of the training set of the ethyl hexanoate, ethyl lactate, ethyl acetate, and ethyl butyrate in the siPLS model were 0.986 4, 0.991 5, 0.970 2 and 0.951 4, respectively. And the correlation coefficients of the test set were 0.982 4, 0.961 9, 0.905 2, and 0.808 0, respectively. These results corroborate the hypothesis that the FTIR-ATR can effectively achieve accurate determination of different grades of base liquor combined with chemometrics, and the quantitative model for rapidly detecting the main esters in base liquor is good, which can meet testing requirements during liquor production. FTIR-ATR combined with chemometrics provide a fast and accurate method for the determination of the grades of base liquor which can effectively enhance the level of intelligent production of liquor.

Graphene oxide (GO) was chosen as the Raman enhancement substrate, and the effect of the number of GO layers and probe molecule water soluble copper phthalocyanine (TSCuPc) films thickness on surface enhanced Raman scattering (SERS) was investigated. In our work, spin-coating method was carried out for preparing GO films with different number of GO layers by using different concentrations, and then different TSCuPc films were prepared by adjusting the speed. The results of the experiments showed that: with the increasing of the layer number of GO films, both the polarizability induced by π—π conjugation and local dipole moment induced by oxygen-containing groups increased, resulting in a stronger Raman enhancement presenting a saturated tendency. Meanwhile, the enhancement of characteristic peaks of TSCuPc linearly increased with the increasing of the thickness of TSCuPc films and compared to the influence of GO layer number, the first-layer effect resulting from the thickness of TSCuPc was less pronounced. The TSCuPc molecule prepared by solution method is generally used for hole injection layer of organic optoelectronic devices and there will be of great significance to improve the hole injection efficiency, transmission efficiency and stability of organic optoelectronic devices by researching the surface enhanced Raman spectrum of GO and TSCuPc.

Based on the phase equilibrium line of coal mine gas (CH4∶C2H6∶N2=67.5∶22.5∶10) hydrate, hydration kinetics experiments with four different driving forces were worked out. The hydrate growth spectra were obtained by using micro-Raman spectroscopy. The hydrates in four experiments were sⅡ type according to the Raman shift of C2H6 C—C bond stretching vibration. The change laws of gas hydrate phase compositions and hydration numbers were obtained based on the model of van der Waals and Platteeuw. The results showed that the stability of hydrate was affected by driving force. When the driving force increased, the CH4 occupied more cavities than C2H6, and the more proportion of CH4 in hydrate phase, was the more stable the hydrate became. The priority levels entering hydrate cavities of N2, CH4 and C2H6 could be determined by using the diameter ratio of object molecular and hydrate cavities. Among these objects, the priority level of CH4 was the highest for small cavities and C2H6 was the highest for large cavities. The description of the guest material transfer law of hydrate growth process based on gas hydrate stability provides a theoretical basis for gas hydrate micro-growth.

Acetic acid is the main component of acids generated through oil-paper insulation aging. The analysis of the content of acetic acid dissolved in the transformer oil is of great significance for evaluating the aging state of operating transformer. Raman spectroscopy is a molecular analysis technology based on the Raman effect, which can be applied to perform non-contact in-situ detection of substance. In this paper, the application of laser Raman spectroscopy in the detection of acetic acid dissolved in the transformer oil was studied. Gaussian 09W simulation software was applied to analyze the Raman vibration characteristics of acetic acid. Also, the vibration modes of the Raman spectral peaks of acetic acid were identified. Acetic acids at different concentrations dissolved in the transformer oil were directly detected based on the laser Raman spectroscopy liquid detection platform. Acetic acid was characterized by Raman signal at 891 cm-1. The quantitative analysis method for acetic acid was established based on the Raman peak area ratio, A891 cm-1/A932 cm-1, and the least squares method. Current detection limits of 0.08 mg·mL-1 acetic acid concentration were obtained. The experimental results show that laser Raman spectroscopy can be used in the analysis of the content of acetic acid dissolved in the transformer oil which has a good detection stability and reproducibility. The research in this paper provides a new alternative method for the rapid and nondestructive detection of acetic acid dissolved in the transformer oil.

Water stress is one of most common stress factors for vegetation. It can reduce cell water potential and stomatal conductance, thus may threaten the process of photosynthesis. Moreover, it can be noninvasively detected by using chlorophyll fluorescence, which is considered as the proxy of photosynthesis due to its sensitive to physiological change. However, chlorophyll fluorescence can be easily influenced by various factors, such as water stress, temperature, chlorophyll content, leaf and canopy structure. As a consequence, the relationship between chlorophyll fluorescence and water stress is significantly complicated. Thus, the study is focused on the rationale of chlorophyll fluorescence and its application in detecting water stress. Firstly, the origin of chlorophyll fluorescence in the view of photosynthesis was briefly introduced. Then, influence factors including chlorophyll content, leaf and canopy structure, ambient factors that affect chlorophyll fluorescence were analyzed. Furthermore, we summarized the application of chlorophyll fluorescence in detecting water stress. Finally, based on the above clarification, we proposed a new strategy of the application of chlorophyll fluorescence in water stress detecting.

In order to enhance the fluorescence intensity and reliability of CdS nanoparticles, synthesis, fluorescence property of CdS by different mass ratio of Cd to S, and influence of stabilizer were studied. CdS/ZnO composite structures were synthesized in alkaline condition using the hydrothermal synthesis method. In addition, all samples were tested by XRD, fluorescence spectroscopy and SEM. The results showed that CdS nanoparticles and CdS/ZnO composite nanoparticles were single and relatively pure. ZnO coated on the surface of CdS. Under the 328.5 nm ultraviolet excitation, emission spectrum was narrow and symmetrical, and the emission peak was at 463 nm. The fluorescence intensity of CdS/ZnO composite structure nanoparticles increased obviously. The best mass ratio of CdS to ZnO was 1∶1, whose fluorescence efficiency was 11% higher than that of CdS nanoparticles. The results of first principle study indicated that the energy band of Cd-4d, S-3p and Cd-5s were comprised of 5, 3 and 1 energy levels, respectively, in the band structure of CdS. By comparing partial density of states in different orbits, it can be seen that the boundary of conduction band was mainly comprised of Cd-5s orbit, the boundary of valence band was mainly comprised of S-3p orbit, and the electronic states near -7 eV was mainly comprised of Cd-4d orbit. In the band structure of ZnO, valence band on top was mainly comprised of O-2p electron, the region near Fermi level was mainly comprised of Zn-3d electron, conduction band was mainly comprised of Zn-3d and O-2p electron. In CdS/ZnO composite structures, energy levels of Zn-3d electron were near energy levels of S-3p electron and presented a type-Ⅱ band structure, thus narrowing band-gap. The electron transition became easier, depressing the recombination of electrons and holes, and improving the efficiency of fluorescence.

The time-resolved and vibrational emission-resolved laser-induced fluorescence (LIF) spectra of jet-cooled supersonic diatomic sulfur molecule S2 have been studied in the range of 30 400~34 400 cm-1, and 184 bands were observed with high (0.1 cm-1) and low (0.3 cm-1) resolutions. 84 vibrational transitions were assigned to the Ｂ ３Σ－ｕ－Ｘ ３Σ－ｇ and Ｂ″ ３Πｕ－Ｘ ３Σ－ｇ, and the molecular constants in the excited states Ｂ ３Σ－ｕ ν=0～9 and Ｂ″ ３Πｕ ν=2～12, including rotational constants, spin-orbit coupling constants, spin-rotation coupling constants, and spin-spin coupling constants, were obtained. The equilibrium molecular geometry in the vibronic ground state of Ｂ ３Σ－ｕ was determined by high-resolution spectrum. As there is perturbation between the Ｂ ３Σ－ｕ and Ｂ″ ３Πｕ states of S2 molecule, the vibrational level intervals, spin-spin coupling constants and spin-orbit coupling constants of Ｂ ３Σ－ｕ and Ｂ″ ３Πｕ states are anomalous variation, as well as the intensity of rotational transition and the transition selection rules. The anomalous behavior of the rovibrational spectra was qualitatively explained by the homogeneous perturbations between ３Σ－３Π states.

A novel coumarin-based fluorescent probe 7-Diethylamino-2-oxo-2H- chromene-3-carboxylic acid quinolin-2-ylmethylene-hydrazide (FKBA) was designed and synthesized to identify Cu2+. FKBA was confirmed by means of IR, EA, MS, 1H NMR, and 13C NMR. The interaction between FKBA and metal ions was investigated via fluorescence spectrophotometry and UV absorption spectrophotometry. The results indicated that FKBA showed excellent selectivity and high sensitivity for Cu2+. Its UV absorption peak was redshift and the maximum UV absorption peaks was also changed when Cu2+ was added. However, under same conditions, it was only a slight change of UV absorption peak after the other metal ions, such as Ag+, Al3+, Ba2+, Ca2+, Cd2+, Co3+, Cr3+, Fe3+, Hg2+, K+, Mn2+, Mg2+, Ni2+, Na+ , Zn2+ and Pb2+were added. The selectivity of FKBA as a chemosensor for Cu2+ was tested by incubating FKBA with a range of environmentally and biologically important metal ions. Fluorescence spectra were notable quenching when Cu2+ was added, with only little interference by other metal ions. Fluorescence spectra of FKBA in the presence of each of different metal ions upon the addition of Cu2+ had the same quenching. Thus, it was notable that FKBA showed good capability of resisting disturbance. The color of FKBA turned from blue to brown upon the addition of Cu2+. The brown of complex restored to the original blue upon the addition of EDTA. The fluorescence intensity regained when EDTA was added, suggesting that fading fluorescence intensity changed due to the formation of KFBA-Cu2+ complex but not any catalytic action of Cu2+. FKBA was not stable and easily hydrolyzed in acidic environment due to their schiff-based structure and part of the FKBA hydrolyzed into other fluorescent substance. Furthermore, the detection limit was 0.13 μmol·L-1 according to the definition by IUPAC (cDL=3Sb/m). FKBA can be used as a fluorescent probe to detect Cu2+ in actual samples.

Biological aerosols widely spreading in the atmosphere will easily result in various epidemic diseases, meanwhile, biological aerosol weapons pose a severe threat to the safety and security of military forces and civilians. It is critically important to remotely detect biological aerosols at real-time. In this work, a double-wavelength laser induced fluorescence lidar was constructed for atmospheric bacterial spores’ identification and thus the early warning. The device employed a Nd∶YAG laser operating at 1 064 and 266 nm, with a repetition rate of 10 Hz. Based on lidar detection principle, a series of numerical simulations were performed to estimate the measurement range of the elastic scattering signals in the infrared band and the fluorescence signals induced by ultraviolet laser. In the ultraviolet band, the signals were analyzed with a spectrograph to evaluate the minimum concentrations of bacterial spores at different pulses. With a relative error of less than 10%, theoretical analysis shows that, within a range of 1.0 km, the system is capable of identifying a minimum concentration of bacterial spores at about 15 000 and 8 400 particles·L-1 at daytime and nighttime with the single laser pulse excitation. With an integrated pulses of 10 000, the detectable abilities of the fluorescence lidar greatly improves, identifying a minimum concentration of bacterial spores at 144 and 77 particles·L-1 at daytime and nighttime, respectively. In the lidar operation, when bacterial spores are located by the infrared elastic signals, one could actually extend the collected intervals in the fluorescence detection to improve the Signal-to-noise ratio, which may lose acceptable temporal resolution.

In this paper, Zn (DPBA) (bpp) complex was synthesized with 2-(3’,4’-dicarboxyphenoxy) benzoate (DPBA) as the first ligand, and 1,3-bis (4-pyridyl)-propane (bpp) as the second ligand. The complex shows a one-dimensional chain structure, and its asymmetric unit includes one Zn(Ⅱ), one DPBA ligand and one bpp ligand. Zn(Ⅱ) ion is coordinated with four oxygen atoms and one nitrogen atom. The complex has good fluorescence property with a wide emission band appearing at 375 nm, which is the π*—π transition of the ligand. Compared with the fluorescence emission of the ligands, the emission peak of the complex is blue shifted, and the emission intensity is greatly enhanced. The fluorescence properties of the complex in common solvents and metal cations were also studied. Experimental results show that the influence of different small organic molecules or different metal cations on the fluorescence of the complex, small organic molecule nitrobenzene and Fe3+ make the fluorescence quenching of the complex. Thus, the complex can be used for the detection of nitrobenzene and Fe3+ ion in the water and ethanol system.

The complex ［Eu(PABA)3(phen)(H2O)］·2H2O (HPABA=p-aminobenzate, phen=1,10-phenanthroline) was obtained by hydrothermal method. It is mononuclear molecule containing {EuO7N2} unit. The coordination number of Eu3+ ion is nine, forming a distorted monocapped square antipriosm. The molecules are linked by hydrogen bonding to a three-dimensional structure. The complex displays a bright red light under ultraviolet lamp. The emission peaks of the fluorescence spectra of the complex are at 595 and 618 nm, corresponding to the 5D0→7F1 and 5D0→7F2 transitions of Eu3+ ion. In addition, the effects of different anions, metal ions and solvents on the fluorescence of the complex was studied. The experimental results show that this complex could be a potential luminescent probe for detecting F-, Pb2+ and nitrobenzene based on fluorescence quenching mechanism.

Human serum fluorescence spectrum within the range of 220～900 nm excited by 240 nm excitation wavelength is studied and analyzed in the modeling for the detection of human serum glucose concentration. Wavelength variable selection strategy was improved on the basis of simulated annealing algorithm and partial least square algorithm. According to the frequency of wavelengths selected in modeling and uninformative variable elimination method, this paper executed a rough and handpicked process for wavelength variable selection which speeded up the convergence rate and reduced the quantity of calculation such as introducing the self-adaptive property for the number of principle components. Basis interpolation functions for partial least square algorithm such as linear, cubic spline function and Gaussian function as well as the original spectra and the 3rd, the 4th detail signal decomposed by Daubechies wavelet were studied and compared in the modeling process. The result shows that the enhancement avoids the time cost by parameter setting attempts, the parameter gradually becomes stable in the calculation process and the best determination of the principle components is found. The prediction and analysis ability for independent samples have been a significant improvement with the new strategy of wavelength variable selection. The minimum least square error for prediction is 0.25 mmol·L-1 in modeling results, which is up to most clinical standards for human glucose level detection. The model is apparently improved by adding the nonlinear condition, of which the best result is based on the spline function, and the second is on the gauss function. Original fluorescence spectra are decomposed and produce a better result for modeling. The 4th detail signal spectra are better than the 3rd detail signal on the whole. Given the experimental condition, the frequency of wavelength selection is meant for the distribution of glucose concentration information, which provides the statistical interpretation for the physicochemical characteristics of glucose in human serum to some extent.

Synchronous fluorescence spectra was applied to assess tyrosine (Tyr) and tryptophane (Trp) residues in the plasma of patients suffering hepatocellular carcinoma, tumor-bearing mice, and cultured cells (HepG2 and HL-7702). The synchronous fluorescence peaks of Tyr and Trp residues were at 318 and 350 nm when Δλ=20 nm and Δλ=80 nm respectively, and did not shift regardless of the sample variations. The results showed that the fluorescent intensities of Tyr and Trp residues increased significantly in the plasma proteins of patients suffering hepatocellular carcinoma. There was a correlation between the increased fluorescent intensities of murine plasma Tyr or Trp residues and the increasing of time of tumor-bearing, indicating that the alterations of Tyr and Trp residues might be associated with tumor development. On the contrary, the fluorescent intensities of Tyr and Trp residues in tumor tissue or HepG2 cells decreased along with the increasing of time of tumor-bearing or culturing. Further experiments showed that a potential anti-tumor medicine-matrine which exerted an anti-tumor activity could enhance the fluorescence intensities of Tyr and Trp residues. These results demonstrated that synchronous fluorescence spectra could be used to determine Tyr and Trp residues in proteins. By this method, we found that Tyr and Trp residues increased in the plasma proteins of tumor bearing patients and mice which might be correlated with tumor development. On the contrary, Tyr and Trp residues in proteins of tumor tissue or cancer cells decreased. It remains unclear whether these changes acted as a biomarker for protein metabolism imbalance or they contributed to the tumor evolution in malignant diseases, which is worthy of further investigation.

Fluorescence conversion film produced through the entrance window of silicon substrate detector is an effective method to reduce the cost of ultraviolet fluorescence enhancement technology. We theoretically discussed the relationship between spin-coating process parameters and properties of UV fluorescence film, a colloid admixture of polydimethylsiloxane and pigment yellow 101. To make further efforts, we set up an experimental platform for the performance measurement of UV fluorescent films, then optimized the mass ratio and spin speed of the spin coating process parameters for the films. There are two primary parameters evaluating spectral analysis detector: one is spectral response sensitivity, the other is spectral resolution. The analysis and experimental results show that the spin speed of making fluorescence films by spin-coating will directly affect the thickness, surface roughness of the film and distribution of fluorescence material, which then affects the resolution of the spectrum analysis system. The efficiency of the UV fluorescence enhanced film is closely related to the mass ratio of fluorescent solvent polydimethylsiloxane and fluorescent material pigment yellow 101. Low mass ratio cannot enhance UV-responsive sensitivity, but high mass ratio and the self fluorescence-quecher effect will reduce it. Eventually, we prepared UV fluorescence enhancement films based on the optimization of film spin coating process. The spin-coating speed was 2 500 to 3 000 r·min-1 and the mass ratio of the fluorescent substance to the fluorescent solvent was 7%. The characteristic spectrum testing results of the mercury lamp indicated that after coating films, UV-responsive sensitivity was improved nearly 1.6 times at 313 nm. Analyzing FWHM of characteristic spectrum with and without coating film, we discovered that there was no effect after coating.

Anion-exchange membranes of bipolar membrane electrodialysis(BMED) which recovered organic acid from butyl-acrylate wastewater were studied. Performances of the membranes were analyzed before and after polluted by butyl-acrylate wastewater. Attenuated total reflection-Fourier transform infrared (ATR-FTIR), scanning electron microscopy-energy spectrum (SED-EDS) and X-ray photoelectron spectroscopy (XPS) were applied to characterize the composition changes of the membrane surfaces. Membrane performance results indicated that the used membranes were polluted with higher area resistance and lower transfer number than new membrane. EDS results indicated that membrane pollutants contained oxygen and carbon atoms, since the composition of carbon and oxygen atoms increased from 78.10% and 8.34% to 81.76% and 12.05%, respectively after the membrane was used. Results of C(1s) analysis of XPS spectra indicated that membrane pollutants contained —COO-Na+, because the composition of —COO-Na+ increased from 8.5% to 13.7% after the membrane was used. ATR-FTIR results indicated that the absorption at 1 561 cm-1, which was asymmetrical stretch vibration of —COO-M+ (M: metal), was enhanced after the membrane was used. The results verified XPS results. As sodium polyacrylate was one of the pollutants in butyl-acrylate wastewater, it was used to pollute anion-exchange membrane. And then, the polluted membrane was analyzed for performance, XPS spectral and ATR-FTIR spectral. The results indicated that polyacrylate resulted in membrane resistance increase, transfer number decrease, —COO-Na+ composition increase, and absorption enhancement at 1 561 cm-1. Therefore, sodium polyacrylate is an important pollutant which can result in pollution of anion-exchange membrane. Spectral methods are useful tools for characterization and identification of fouling pollutants on ion exchange membrane.

Aiming at aircraft airborne environment multi-parameter comprehensive testing requirements, by analyzing the theories and experimental results, a kind of fiber Bragg grating (FBG) gas pressure and temperature integrated monitoring method based on spectral reflectance characteristics identification is studied, and the dual parameter sensing mechanism as well as its theoretical model based on the diaphragm structure are also studied in this paper. OptiGrating software based on the coupled mode theory was used to simulate the reflection spectrum of the fiber Bragg grating sensor under different pressure and temperature conditions. Therefore, the characteristics of fiber Bragg grating sensor under different pressure and temperature conditions in simulate environment appeared. On this basis, with the aid of the flat diaphragm pressure sensitive structure enjoying a excellent elasticity and recovery performance, a diaphragm type double optical fiber gas pressure/temperature integrated monitoring system was constructed, and the package of the diaphragm type double fiber optic pressure/temperature sensing model was studied. Beyond that, the performance characteristics of the sensing model was also presented. A series of data analysis of the experiment showed that the strain sensing fiber Bragg grating reflection spectrum shifted to short wavelength direction under the condition of constant temperature with the increasing of the gas pressure, and the strain sensing fiber Bragg grating reflection spectrum sensitivity coefficient was about 0.803 0 nm·MPa-1. The reflection spectrum peak and the sidelobe level showed a good linear relationship with the pressure changing. When the air pressure was constant and temperature changed, fiber Bragg grating center wavelength sensitivity of temperature sensing fiber Bragg grating which was not affected by strain and only sensitive to temperature was about 9.39 pm·℃-1. However, when the pressure and temperature cross changed, micro pressure can be monitored in real-time under the condition of variable temperature. Fiber Bragg grating sensing by the inhomogeneous strain effect has certain chirp reflection spectra, the sidelobe peak wavelength of reflection spectrum will shift because of the change of temperature and pressure, which needs measurements at any moment in accordance with the monitoring environment. It has to be noticed that the temperature and pressure both have a good linear relationship with the fiber Bragg grating reflection spectrum center wavelength, and the spectral reflectance under different air pressure corresponding to the same order number sidelobe peak amplitude is equal. The above research provides a useful help for online comprehensive test of multi physical parameters in aviation spacecraft system.

Based on absorption principle, the paper calculated parameters of Beer-Lambert law to measure the light length. The paper analyzed Gaussian lineshape, Lorentzian lineshape and Voigt lineshape, and used the Voigt lineshape to fit the spectrum signal. The peak value of the Voigt lineshape, Lorentzian width and error function were also studied. The direct absorption spectroscopy of TDLAS was used to measure the oxygen absorption spectrum getting the fitted peak value. The light length was calculated as 66.55 cm through putting the peak value into the Beer-Lambert function. The value of comparative measurement was 66.04 cm, and the measurement accuracy was 0.78%. So, this method is suitable in light length measurement.

In this study, the adsorption of lead(Ⅱ) from aqueous solution by rape straw powders was investigated. Box-Behnken Design(BBD) accompanied by response surface methodology (RSM) were employed to optimize various environmental conditions for biosorption of pH, concentration of lead ions, particle size, biosorbents loading and contact time using rape straw powders as absorbent. The models of kinetics and isotherms were used to evaluate the behaviors of biosorbent for uptaking lead(Ⅱ) from aqueous solution by rape straw powders. The functional groups of rape straw powders which played roles were recognized by Fourier transform infrared spectra. The results revealed that the parameters of pH and biosorbents loading were the key factors affecting the efficiency for the removal of lead(Ⅱ) from aqueous solution. R2 were 0.966 4, 0.970 1 and 0.964 9 for uptaking lead(Ⅱ) from aqueous solution by rape straw pith core, shell and seed pods, respectively, indicated the validity of the model. The experimental data was better described by a pseudo-second-order model compared with the intraparticle diffusion model. In comparing the analysis of Langmuir and Freundlich isotherms, the adsorption of lead ions showed a better fit with the Langmuir isotherm model. According to the Langmuir equation, the maximum adsorption capacities of rape straw pith core, shell and seed pods for uptaking lead(Ⅱ) from aqueous solution were 135.14, 78.74, 90.09 mg·g-1, respectively. Comparing the graphs of infrared spectroscopy of straw pith core, shell and seed pods before and after the Pb(Ⅱ) removal, we discovered that the spectra changed, particularly active groups, such as hydroxy, carboxyl and amide groups of the protein, which played major roles in the biosorption process. The study of results provided evidences that rape straw powders can be used for removing Pb(Ⅱ) from sewage water.

The effect of disposing the oil wastewater in Liaohe Oilfield by sunlight/Fenton method was studied in this paper, and the reason why the sunlight/Fenton method was better than the common Fenton method was analyzed. The wastewater mainly contains benzene and alkane compounds. Effect of sunlight/Fenton method on oil field wastewater treatment in Liaohe was related to height of the water layer. The removal rate of aqueous COD decreased when the height of the water layer increased, and the penetration ability of sunlight to this oilfield wastewater was about 1 m. When the height of wastewater was about 40 cm, COD of wastewater reduced from 430 to 63.2 mg·L-1 after treatment of oil wastewater by sunlight/Fenton method. It is proved that the form of the poly ferric compounds generated in the system by using the UV-Vis spectroscopy, infrared spectroscopy (FTIR) and X-ray diffraction method (XRD) is the same as the poly ferric compounds generated by the common Fenton system. At the same time, the transformation processes of benzene and alkanes were studied by UV-Vis spectroscopy which indicated that the transformation processes of alkanes in sunlight/Fenton were as same as the common Fenton method; enzene could be converted into photosensitive molecules activated by hydroxyl radical in sunlight/Fenton system. Thus, the sensitivities of the aromatic intermediates are the reason why the sunlight/Fenton method is more efficient than the common Fenton method.

The rape and rice straws were collected in the West Sichuan Plain. The spectral characteristics of dissolved organic matter (DOM) released from the decomposing process of crop straws were characterized by the UV-Vis spectrum, Fourier transform infrared spectrum (FTIR) and three-dimensional excitation emission matrix fluorescence spectrum (3D-EEM). The difference of spectral characteristics of DOM in rapid leaching stage (0～0.5 days) and straw decomposing process (0.5～90 days) was clarified. The effect of straws to ecosystem structure in the conservation tillage pattern was tracked, and the variation mechanism was analyzed. The difference of DOM spectral characteristics in decomposing processes was significant. The dissolution of aromatic substances, degradation of components and formation of humus also presented in the processes. The E2/E3 value of DOM released from the rapid leaching stage of the straw was the highest, while the value of SUVA254 was the lowest, which suggested the aromaticity and molecular weight of DOM at the stage were relatively lower than those in other periods. The dissolution of aromatic components predominantly occurred in the early stage (≤10 days) when the E2/E3 value decreased gradually, but the SUVA254 value increased. And, the peak of polysaccharide, aromatic carbon and amide absorbent apex in DOM weakened. However, the persistent cellulose, hemicellulose and macromolecular protein were decomposed in the later period. The IR bands of DOM consisted of the amino acids, peptides, proteins, polysaccharides, phosphate skeleton, purine bases, pyrimidine and other components were mainly caused by the vibration, stretching, bending or hydrogen bonding of N—H, O—H, CO, CC, C—O, C—H and —COO- functional groups. Microorganism activities were vigorous in the early and middle stages of decomposition, which made degradable sugar and protein-like rapidly running out. DOM released from rape straws in the early stage showed a high bioavailability, due to the protein-like with the low molecular weight and unstable characteristics. The DOM of rice straws contained more organic matter than the rape, and had more humus relatively. The —OH and CO of DOM can disturb the migration and transformation of non-ionic polar OCs through covalent bonds in the soil. With the decomposition, —OH was, to a certain extent, decomposed by microorganisms. In this case, the interaction between DOM and OCs became weaker, and the phenols, carbonyls and carboxylic acids gradually enhanced the interaction between DOM and OCs or metal ions. Therefore, DOM regulated the migration and transfer processes of OCs in farmland soils. This study provides the basic data and new evidence for environmental significance of straw-return in the West Sichuan Plain, and the support for agricultural waste treatment and resource recycle in the area.

Quartz-enhanced photoacoustic spectroscopy (QEPAS) technology invented lately uses a commercially available mm sized piezoelectric quartz tuning fork (QTF) as an acoustic wave transducer. A high Q-factor and a ~30 kHz resonance frequency of the QTF improve QEPAS selectivity and immunity to environmental acoustic noise. QEPAS sensor has the advantages of high sensitivity, selectivity and compactness. Acetylene (C2H2), a toxic and harmful gas, has great significance in high sensitive detection in many fields such as the detection of fault gases in transformers and environmental monitoring. In this paper, QEPAS technology was employed to detect C2H2. A continuous-wave distributed feedback (DFB) single mode diode laser emitting at 1.53 μm was used as the exciting source. In order to reduce the sensor background noise and simplify the data process, a wavelength modulation spectroscopy and a 2nd harmonic detection technique were employed. To increase the QEPAS signal amplitude, unlikely the usually used quartz tuning fork (QTF) with resonance frequency of 32.768 kHz, a novel QTF with 30.72 kHz was adopted as the acoustic wave tranducer. The position between laser beam and QTF and the laser wavelength modulation depth were optimized. In the meanwhile, micro-resonator was added into the QEPAS sensor system, and the length and inner diameter of the mR tubes were selected to be 4 mm and 0.5 mm, respectively. Finally, a 2.7 ppm minimum detection limit was obtained, and the corresponding normalized noise equivalent absorption (NNEA) coefficient was 1.3×10-8 cm-1·W·Hz-1/2.

Sooty mould is one of very common plant diseases in the tropical and subtropical regions of southern China, which does great harm to China’s agricultural production. Monitoring and forecasting this disease provide a significant foundation and basis for the implementation of effective governance measures. To establish hyperspectral based data for Sooty mould severity level inversion model, this study collected 50 Cinnamomum Septentrionale samples’ hyperspectral data by ASD FieldSpec HandHeld type spectrometer in Beibei, Chongqing. Leaf area data was obtained through the digital camera and ENVI software, and the sooty mould severity was calculated by the ratio of sooty mould area and the whole leaf area. Then, a regression model was established by the maximum correlation between the sooty disease severity and the spectral reflectance data. This study shows that health leaves at around 560 nm band have obvious reflection peak, and when the severity of Sooty mould increases, the reflection peak gradually disappears. The spectral reflectance is negatively correlated with Sooty mould disease level in visible light and near infrared band, and the 500～650 and 720～850 nm are the sensitive spectral bands of Sooty mould. The correlation maximum point is in the 550 nm band, and the correlation coefficient reaches -0.72. By the analysis of Sooty mould severity with multi band spectral reflectance data, this study concludes that the 785 nm band has the largest correlation with disease severity and its regression model Sooty mould. The coefficient of determination (R2) reaches 0.875. Through the significance test and the prediction accuracy of the model, the conic model established at 785 nm is the best, which proved that the conic model based on the 785 nm band is effective in inversion of Sooty mould severity in single leaf scale.

Abundance or deficiency of soil elements is an expression of soil fertility. Rapid detection of elements in soil is a key point of front information acquirement tools in precision agriculture, and it also provides a theoretical basis for pollution prevention of soil heavy metal and sustainable development of agriculture. This research focused on using laser-induced breakdown spectroscopy LIBS) technique combined with calibration curve and chemometrics method to conduct the simultaneous quantitative analysis of multi-elements (Al, Fe, Mg, Ca, Na and K) in soil. First of all, five certified reference materials (CRM) of soil numbered GBW07446, GBW07447, GBW07454, GBW07455, GBW07456 were ablated by a laboratorial LIBS setup in air. 50 LIBS spectra of each type of soil were averaged to reduce the error in experiment process. By integrating the acquired LIBS emission spectra and atomic spectra database from national institute of standards and technology (NIST), analytical spectral lines and corresponding spectral regions were identified. Then, calibration curves of the intensity of a peak and integrated intensity of a peak or several peaks (peak area) coupling with the element content s were fitted. The results indicated that the linear relation from the calibration curves fitted by peak areas and element contents were superior to the calibration curves fitted using intensity of a peak and element contents (except the Fe). Meanwhile, partial least-squares regression (PLSR) was employed to build the quantitative model by using the selected spectral regions and corresponding element contents, which offered a promising result with relatively high RP and showed more advantages than the calibration curve method. The approach revealed that LIBS technology combined with chemometrics methods displayed a bight prospect in the field of spectrochemical analysis. The achievements of the research not only provide a guide for detecting soil nutrient spatial distribution and precision fertilization technique, but also lay a theoretical foundation for developing the portable LIBS detector used in the field.

Engine oil plays an important role in the engine operation. Elements composition and concentration in engine oil will be changed as the engine operates, which can lead to the deterioration of engine oil, and the engine thereby will be worse. A rapid and effective detection approach for oil performance, therefore, is proposed to prevent further deterioration. Indirect ablation laser induced breakdown spectroscopy (IA-LIBS) is a new technology introduced specially for oil samples, which focuses on the indirect ablation of oil samples by metallic plasma with high temperature, improving the detection sensitivity and stability. In this paper, the matrix effect on calibration curves of analytical elements (Mg, Fe and Ni) in different oils was investigated. The results show that the matrix effect is quite small and reasonably negligible. A universal calibration curve can be established for analytical metals in different types of oil, and the linear fitting coefficients are all superior to 0.99. We used the universal calibration curves to determine the concentrations of Mg, Fe and Ni in mixed oils. The IA-LIBS results show a good agreement between the measured and known values. The IA-LIBS is further improved and can promote the detection of engine oil performance, which has important scientific significance for the diagnosis of engine wear.

Vector Space Model (VSM) was originally used in document retrieval. It is characterized by extracting the texts from the document and converting the document into a text vector space. VSM compares the similarity between document text vectors and text retrieval text vectors. The document retrieval is accomplished according to the similarity based on the nearest template principle of template matching in pattern recognition. This article applied such principle into the identification of samples based on the characteristic of LIBS spectrum. To create the database of characteristic peaks of training dataset, we obtained the spectra template of all kinds of samples from the training dataset and extracted the wavelength and intensity of peaks from the spectra template. In another hand, to create the database of characteristic peak vectors for all the training samples, we calculated the spectral characteristic peak weight and converted the spectra to peak vector space. The characteristic peak vector of the test dataset was obtained by the same way. The cosine value between the characteristic peak vector of test data and every characteristic peak vector in the database were calculated and the maximum cosine was taken as the identification result. Geological cuttings, the research subject, were identified by the VSM in this paper. The result demonstrated that the VSM could rapidly identify the spectra from 4 kinds of geological cuttings’ LIBS spectral and the correct identification rate was 100% after the spectra of the test dataset were averaged. The proposed LIBS spectral identification method based on VSM can be expanded to the identification of other spectral data.

A new method was developed for the determination of twelve different trace impurities in high purity chromium by ICP-MS after chloroformylation separation. The interferences on analytes and the pollution of sample introduction system were efficiently avoided by separation impurity elements from matrix chromium which makes use of chromyl chloride’ low boiling point. The influences of temperature and dosage of acid separation effects were studied. The content of 50V and 50Ti changing with the amount of residual chromium in sample solution was determined. The analytical results proved to be accurate and validated by comparing the proposed method with ICP-OES and AES with D. C electric as the excitation. Under optimized conditions, over 99.99% of the matrix chromium was removed by chloroformylation separation at 130 ℃ with the acid addition of 12 mL for 2 h, which eliminated the matrix effect and spectra interference in the following ICP-MS detection. It showed that the detection limit of the method was 0.000 01%～0.000 06%; the RSD was 1.7%～5.8%; and the recovery of standard addition was 90%～104%. The method is simple, applicative and suitable for the determination of impurities in high purity chromium of 99.99%.

Solution Cathode Glow Discharge-Atomic Emission Spectrometry is a novel, rapid, high efficient and real-time online element analysis method, which can be applied for metal elements detection in water. In this paper, the internal standard method was employed to improve its accuracy and stability. The standard calibration curve of potassium and the internal standard calibration curve of potassium were established using Hβ as internal standard elements, and the relative error and relative standard deviation of the sample measured by internal standard method were 1.11% and 2.14%, respectively. Compared with the standard curve method, the accuracy and stability were improved by internal standard method. Variations of spectral line intensity at the same periods were investigated, showing the spectral line intensity variations of potassium and Hβ were not quite the same, but the spectral line intensity variations of potassium and rubidium, calcium and magnesium in the same main group had the same variable trends, thus, we proposed that the elements which had the same variable trends of spectral line intensity and main group with the determined metal elements could be selected as the internal standard element to have a greater correction for metal elements detection in water using solution cathode glow discharge-atomic emission spectrometry. The accuracies and stabilities of internal standard method when rubidium, magnesium and calcium were used as internal standard elements for potassium, calcium and magnesium were discussed and the relative errors were 0.49%, 0.02% and 0.30% respectively, and the relative standard deviations were 1.11%, 1.13% and 0.87%, respectively, which is better than the standard curve method and the internal standard method using Hβ as the internal standard element. The relative error and relative standard deviation of the calcium and magnesium in tap water were also measured, which showed that the relative error and relative standard deviation were 0.58%, 1.03% and 1.57%, 1.10%, respectively, when magnesium and calcium were used as the internal standard spectral elements respectively. The results show that the internal standard method is a useful method to eliminate the influence of experimental fluctuations, which improves the accuracy and stability when solution cathode glow discharge-atomic emission spectrometry is applied for metal elements detection in water.

In order to acquire the fundamental materials science information of the Neolithic jade jue in Taihu Lake basin (for example, the main minerals and hardness), and explore the evolution law of the jade raw material in pace with time and the possible sources of the jade raw materials, this paper takes the jade jues unearthed from three representative Neolithic sites-Tianluoshan, Xiantanmiao and Jiangjiashan in Zhejiang province as the research objects. These jade jues were nondestructively analyzed by X-ray diffraction (XRD) and external beam proton induced X-ray emission (PIXE). The results suggest that the jade jues analyzed were mainly made of fluorite, dickite, chalcedony, muscovite, tremolite and serpentine dated from Hemudu culture to the late Songze culture. Among them, fluorite, chalcedony and dickite accounted for a large proportion and were applied much earlier than tremolite and serpentine. Combined with the previous researches, we discuss the change of characteristics of the jade jue raw materials unearthed from the relative sites along with time, the possible sources of the jade raw materials, and the internal relation between the material science characteristics and processing technique.

White dwarf main-sequence star (WDMS) is a detached binary star system consisting of a white dwarf primary (WD) and a low-mass main-sequence (MS) companion. Despite the relatively smaller number of WDMS spectra, WDMS has positive significance to the study of evolution of close binaries, especially the evolution of common envelope (CE). The Sloan Digital Sky Survey (SDSS) released the latest data (DR12) which was the final data release of the SDSS-III, containing all SDSS observations. Based on the WDMS spectra identified in previous work, in this paper, we proposed an automatic and efficient method for measuring parameters of WDMS spectra. Least square method was used to decompose the WDMS spectra and the basic parameters including effective temperature、surface gravity and metallicity derived by template matching. Graphical processing units (GPU) was carried out to solve the problem of large computation in parallel mode. Experiment result showed that our code gave excellent performance and accuracy for spectra decomposition and had a 32.128X speedup compared with the serial CPU program.

With the development of spectral imaging towards higher space resolution, higher spectral resolution and higher signal to noise ratio, some problems have appeared in the traditional spectral imager, for example, data acquisition quantity is too big, the resolution is affected by frame frequency and pixel size of detector, precise alignment is difficult for big caliber and long focus system, and hard to develop signal to noise ratio because of limited optics power. To solve the above problems, a single dispersion spectral imager based on compressed coding is studied. Specially, for the lack of system realization and experiment verification at home, the designation, realization, mathematic model and reconstruction algorithm under multi-frame measurement are mainly studied, and the prototype testing and data processing are achieved. At last, some key problems still need to study, such as code error analysis, multi-model and multi-algorithm, system demarcation, and reconstruction evaluation. This imaging system is consisted of object glass, coding template, dispersion element, collimating lens, focus lens and detector, and hyperspectral data was reconstructed by sparse reconstruction algorithm. There are many advantages in the new system, for example, a smaller data size due to the sparse sample of multi-information, a higher resolution because of code super-resolution, an easier implementation for lower hardware requirement, a higher optical energy usage because the code is instead of slit. The results show that the measurement is efficient, the design of prototype is proper, reconstruction algorithm and calibration method are accurate, the space information of alphabet HSI object is clear, and the spectral information of alphabet HSI object is accurate and closed to tungsten lamp spectral, so the system designation and engineering realization are feasible.

In the aerospace field, aiming at the requirements of thermal response monitoring of composite structures in space service environment, a monitoring method for carbon fiber honeycomb sandwich structure based on fiber Bragg grating (FBG) reflection spectrum characteristics analysis under different thermal loads was studied. The fiber Bragg grating (FBG) sensors were implanted in different layers of carbon fiber honeycomb sandwich structure respectively. By monitoring the fiber Bragg grating (FBG) reflection spectrums of each layer under different thermal loads, the associated thermal strain characteristics of the honeycomb sandwich structure can be obtained. The results show that, certain differences exist in the thermal strain characteristics of different material layers in the carbon fiber honeycomb sandwich structure. As the temperature increases, the center wavelength of reflection spectrum of fiber Bragg grating (FBG) implanted between the outer skin surface and the glass cloth shifts to the long wave direction and the waveform of the obtained reflection spectrum changes insignificantly. As the temperature decreases, the reflection spectrum of fiber Bragg grating (FBG) implanted between the second and the third layers of the carbon fabric prepreg appears chirp effects gradually, such as sidelobe, multi-peak, etc. The main-peak center wavelength and the right sub-peak center wavelength of the reflection spectrum both shift to the short wave direction gradually. The peak amplitude of the main-peak does not show significant change and its temperature sensitivity is about 5.56×10-3 dBm·℃-1. The peak amplitude of the right sub-peak increases significantly and its temperature sensitivity is about 40.32×10-3 dBm·℃-1. The full width at half maximum（FWHM）of reflection spectrum of fiber Bragg grating (FBG) implanted between the inner skin and the honeycomb core increases gradually at a rate of 3.19 pm·℃-1 with the temperature decreasing. The reflection spectrum appears a multi-peak trend significantly due to the uneven thermal stress distributed between the layers. The interlaminar thermal strain of each implanted layer increases in similar trends within the increasing temperature range of -70 ℃ to +60 ℃. But at the temperature range of +60 ℃ to +120 ℃, the changing trend of the interlaminar thermal strain between each implanted layers shows significant differences. These characteristics can provide useful help to the following on-orbit status monitoring of composite spacecraft structure in space environment.

Spatial heterodyne spectroscopy has been used in atmospheric trace gases remote sensing field because of its high signal to noise ratio and spectral resolution, and the adaptive correction is a key link in spectrum pretreatment. Based on the spectral characteristics, two methods: the threshold fitting and improved empirical mode, were used separately to correct baseline in measured near infrared moisture spatial heterodyne spectrum. Results show: both the two methods can realize spectral baseline deduction automatically; in addition, the spectral distortion and similarity are 0.761 and 0.955, respectively, when using threshold fitting, and the spectral distortion and similarity are 0.717 and 0.954 (somewhat better), respectively, when using improved empirical mode. As far as the time-consuming is concerned, improved empirical mode using fewer iterations to attain the final baseline spectrum, which is no more than one-tenth of the threshold fitting.

In order to improve the accuracy of interference of Fourier transform infrared spectrometer, we design an automatic regulating system based on integrative beam splitter. Using optical glue to fix the prism and beam splitter. Three adjustment structures was set on the integrative beam splitter. The O point is fixed as the reference point, and piezoelectri ceramics are loaded on the X point and Y point.Using the piezoelectri ceramics to drive beam splitter for tiny displacement adjustment.When the moving mirror moves in constant speed, using four quadrant detector to test the phase difference of three signals. Then three signals are enlarged, filtered and digitized. Using the ECAP of DSP to catch three signals and Using the increment PID to conduct real time control the adjustment of three signals based on phase difference. These three signals is sampled by the AD of DSP. All the information measured can communication with the host PC through USB2.0, then finally reading collection data and real-time demarcating the wave show. The ultraviolet radiator is installed on the holder, the irradiation of ultraviolet light on optical glue is increased when the ajustment start. So that the integrative beam splitter is made which can meet the demand of fourier transform infrared spectrometer. The experimental results show that the design of automatic regulating system based on integrative beam splitter has advantages of simple structure, high adjustment accuracy which can meet the demand of common infrared beam splitter.

In the field of noninvasive blood glucose sensing by near-infrared (NIR) spectroscopy, spectra are highly susceptible to the influence of background variations caused by the measuring instruments and physiological variations from the measured object because the concentration range of glucose in blood is usually small. It should be noted that the influence of background variations cannot be entirely removed; reasonable methods should be adopted in order to reduce the consequence of background variations to an acceptable level. One of the most common methods is to select a relatively stable standard material which shows similar optical property to the measured objects as the reference to perform the measurement. In order to maximize the elimination effect on the influence of background variations and realize a relatively accurate extraction of the glucose concentration information, a reference measurement method combined with double-beam spectra collection and net analyte signal (NAS) processing is proposed in this article. Spectra of the measured samples and reference substances are collected simultaneously with a double-beam double-detector measuring system. The NASs of glucose are obtained by projecting every spectrum of measured samples on the noise background subspace spanned by the spectrum of the reference substance. Experiments are conducted in pure absorption and strong scattering medium respectively. Two-dimensional correlation spectroscopy (2DCOS) and partial least squares regression (PLSR) are adopted as data processing methods to test the effectiveness of the reference measurement method. Results of 2DCOS show that the specificity of glucose concentration information in samples can be improved to a large extent by NAS processing compared to the reference subtraction method. Meanwhile, the root-mean-square error of prediction (RMSEP) of PLS model predicting glucose concentration decreases by 35.25% and 37.95% respectively in the double-beam experiment of glucose aqueous solution and 20%-intralipid solution compared with those in the single-beam experiments. These two RMSEPs further decrease by 26.11% and 14.84% after combining NAS processing with the double-beam experiment data. These results prove that the method of combining double-beam measurement with NAS processing is effective in extracting the glucose information and improving the accuracy of the calibration model, which provides more possibilities for noninvasive blood glucose sensing.

A novel edge-filter wavelength demodulation technique based on the special spectral characteristics of chirped fiber grating and long-period fiber grating was proposed in this paper, which offers a fast wavelength demodulation method for interferometric and resonance fiber-optic sensors. In this wavelength demodulation system, the chirped fiber grating acts as a rectangular filter, which extracts one interferometric peak out of the periodic interference spectrum; The long-period fiber grating acts as an edge filter, whose transmission profile is shown to be nearly linear over a sufficiently wide range, converting the wavelength variation into optical power in a linear relationship, that the wavelength can be acquired through optical power measurement. The demodulation range can go up to one free spectrum range (FSR) and the demodulation speed is determined by the response of the photodetector theoretically. This demodulation technique has practical significance with the fast demodulation speed, wide demodulation range, low cost, small size, and the convenience to multichannel extension. The principle and structure of the demodulation system were illustrated in detail, and the experiment was setup through applying the demodulation system to an interferometric fiber optic current sensor. Experiment result showed the system could demodulate accurately and fast when the sensor was under power current and pulse current. This paper is of great significance for promoting the engineering practical level of interference and resonance fiber optic sensors.

Degradation of grassland causes changes in internal properties of soil, such as the structure and characteristic of humic acid. Humic acids were extracted from a steppe soil under different degeneration stages. Elemental analysis and 13C nuclear magnetic resonance spectroscopy were used to study the structural changes of soil humic acid in the steppe soil. Structural changes in HA was investigated with Factor Analysis. The results showed that the basic carbon frameworks of HA were similar under different degeneration stages. During the process of degeneration, the content of aromatic carbon, and carbohydrates in soil HA decreased. In addition, the oxidation of HA was increased while the hydrophobicity was declining. During the recovery process, the content of aromatic carbon, and carbohydrates in soil HA increased while the hydrophobicity was declined. The aromaticity and polymerization of HA in S. bungeana area, S. bungeana+A. Sphaerocephala area was higher with lower oxidation; the acidity of HA in fenced area was higher, but the aromaticity and polymerization were lower. The results verified that vegetation recovery imposed an important effect on humic acid structure; besides, aromatic groups and aliphatic groups played an important role in the formation of stable humic acid structure.

The measurement of K shell fluorescence parameters is an easy and practical way to investigate the electronic structures of elements in alloys, compounds or complexes. Since the number of valence electrons will change the screening effect, the measured parameters will be affected from the changes. In this study, the measured parameters were investigated for sulphur element according to the number of CH2 groups. For the experimental measurements, the samples were excited by 59.5 keV γ rays from a 241Am annular radioactive source. The emitted K X-rays from the samples were counted by ab Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV.

Due to the fact that the photoelastic modulator (PEM) interference signal frequency ranges from hundreds of megahertz to several gigahertz, and the array detector can not be applied to such high responded frequency, the application of PEM in spectral imaging is greatly limited . To solve this problems, a method is proposed in this paper to produce two PEMs of slightly different resonant frequencies with f1 and f2 which are applied to modulate the inputting optical signal. This method operates two PEMs of slightly different resonant frequencies f1 and f2 respectively, and the incident light can be modulated by the frequency difference of two PEM system. Thus, the interference signal contains low frequency modulation components contains the information of the incident light, and low frequency modulation component consists of a series of frequency-multiplier signals whose fundamental frequency is (f1-f2)/2. This low frequency modulation components can be detected with normal detector. After filtering the direct current component and high frequency signal, the incident light spectra can be obtained by the corresponding calculation. Since the difference frequency can be 2~3 orders of magnitude lower than the original resonant frequency of PEM, it can offer more time to array detector to process the inputting signal. What’s more, it does not require the same path difference and resonant frequency for the two PEMs, which can reduce the difficulty to PEM modulator design and control.

Based on the laser Spontaneous Raman Scattering (SRS) technique, a multi-channel optical diagnostic system is developed for quantitative measurement of mole fraction of gas. A laser pulse stretcher is designed for the 532 nm green laser to efficiently avoid any unwanted phenomena including gas cracking and quartz glass damage due to the impact of high-energy of pulsed laser. The system can also be used to enhance the signal-to-noise ratio of gas Raman scattering spectrum. Under a standard atmospheric temperature and pressure, Raman scattering measurements are carried out in an air excitation zone within a gas cell. The length and the diameter of the cylindrical excitation zone are 66 and 1 mm respectively. Raman spectroscopy and mole fraction of O2 and N2 within each channel are obtained from the tests, together with the relative response factor of O2 to N2, the RO2. In total, 26 repeated experiments are conducted; and all of them are deduced from an accumulated spectrum of 200 laser shots. It shows that the standard deviations between the results of each channel in terms of the averaged mole fractions of O2, O2 and the averaged relative response factor of O2/N2, O2 are 0.015 and 0.024, respectively. However, the channel-averaged value of these parameters is exactly the same as the result obtained with a merged-channel-mode. The accuracy of the measurement is 98%, indicating that this system can fully meet the requirements of real time quantitative measurement for mole fraction of gas mixture with providing spatial and temporal resolution. The present system satisfies the spectral measurement and analysis of various dynamic combustion processes.

Illegal production of alcoholic beverages is a common problem in most countries. The consumption of these counterfeit alcoholic products in Turkey has increasingly been one of the major health concerns. In this study, a comparison between GC-MS and Raman spectroscopy techniques was made to determine the amount of methanol in BogmaRaki which is a counterfeit alcoholic beverage produced and consumed in Hatay region. Different ratios of methanol/ethanol concentrations were prepared to obtain a calibration curve. This curve was used to measure the amount of methanol in the actual product samples using both GC-MS and Raman spectroscopy techniques. Results obtained from both techniques were compared using Paired sample t-tests. The Limit of Detection and the Limit of Quantification values were determined as 0.03 (%v/v) and 0.11 (%v/v), respectively. Both techniques demonstrated a similar sensitivity in the determination of methanol concentration in these counterfeit products (p>0.05). Raman Spectroscopy, however, has an advantage of being easy to use, inexpensive, rapid and non-destructive analytical technique with little or no sample preparation.

The molecular structure of (1S,2R)-2-amino-1-phenylpropan-1-ol (abbreviated as 2APPO) conformers have been studied in the gas phase. Natural Bond Orbital Analysis and Non Linear Optical properties of 2APPO have been performed by DFT level of theory using B3LYP/6-311++G(d,p) basis set. The atomic charges, electronic exchange interaction and charge delocalization of the molecule have been performed by Natural Bond Orbital (NBO) analysis, Natural Population Analysis (NPA) and Non Linear Optical (NLO) properties have been constructed at B3LYP/6-311++G(d,p) level to understand the optical properties.