Preliminary Study on the Nearc-ground Spectral Characteristic of the Degraded Meadow Grassland

IS1921 VF-256 type ground object spectrometer was used to extract the spectral data of the meadow grassland and bare land to obtain their refleotivity spectral characteristics. The experiment was carried out on the low mountain meadow steppe in the Saiwundu Village, Hargentai Town, West Ujumqin Banner, Xilin Gol League, Inner Mongolia. The results showed that different ground objects had different reflectances. The spectral reflectance curve of the meadow steppe plant communities had obvious characteristics of peak and valley in the visible spectrum band, and had strong reflection in the near-infrared band. The reflection curve of the bare lands in the visible spectrum band was higher than that of the meadow grassland communities while inthe near-infrared band it was lower than that of the meadow grassland communities. Under different degradation gradients, the spectral reflectivity of the meadow steppe grassland communities increased with the enhancement of the degradation gradients. Under the same degradation gradient, the Stipa grandis communities had a lower visible light reflectivity than the Artemisia frigida communities but had a higher near-infrared reflectivity than the Artemisia frigida communities; different ground objects on the meadow steppe had different spectrum characteristic, and showed a certain discrepancies with the changes of the degradation level.

Analysis on Reflectance Spectral Characteristics of Typical Saline Soil in Arid Area

The spectral characteristic of geography objects is not only the important content of remote sensing mechanism, but also the important basis for remote sensing application. The reflectance spectral characteristics reflect the physiochemi-cal properties of saline soil. With 3 kinds of typical saline soils in the arid area as the study objects, the reflectance spectrums of soils with different salt contents and soil moistures were measured, and the spectral characteristics of the spectrums were analyzed. The results showed that under dry condition, the reflectance of the three kinds of saline soils presented obvious high-low patterns, while under damp condition, there was no obvious pattern. With continuum removed ,the three kinds of saline soils showed significant difference in reflectance spectral characteristics. There was significant difference in the absorption depth of the two absorption val eys un-der dry and damp conditions, which could be used to identify these 3 saline soils. The result of this research can be used for the parametric inversion and classifica-tion of saline soil retrieval and classification, as wel as for the remote sensing monitoring on saline soil.

Effects of Ce^(3+) on improvement of spectral characteristics and function of chloroplasts damaged by linolenic acid in spinach

Linolenic acid has great effects on the structure and function of chloroplast. We studied the effects of Ce3＋ on the improvement of chloroplast spectral characteristics and oxygen evolution damaged by linolenic acid in spinach. Results showed that Ce3＋ could decrease the light absorption increased by linolenic acid and promote the distribution of excitation energy to PS II and alleviate the decrease of PS Ⅱ fluo- rescence yield caused by linolenic acid. The linolenic acid treatments in various concentrations reduced the oxygen-evolving rate of chloroplasts, but the rate was accelerated since adding Ce3＋.

Identifying camellia oil adulteration with selected vegetable oils by characteristic near-infrared spectral regions

In this paper,a methodology based on characteristic spectral bands of near infrared spectroscopy(1000-2500 nm)and multivariate analysis was proposed to identify camellia oil adulteration withvegetable oils,Sunflower,peanut and corn oils were selected to conduct the test.Pure camlia oiland that adulterated with varying concentrations(1-10%with the gradient of 1%,10-40%withthe gradient of 5%,40-100%with the gradient of 10%)of each type of the three vegetable oilswere prepared,respectively.For each type of adulterated oil,full-spectrum partial least squarespartial least squares(PLS)models and synergy interval partial least squares(SI-PLS)modelswere developed.Parameters of these models were optimized simultaneously by cross-validation,The SI-PLS models were proved to be better than the full-spectrum PLS models.In SI-PLSmodels,the correlation coefficients of predition set(Rp)were 0.9992,0.9998 and 0.9999 foradulteration with sunflower oil,peanut oiloil seperately;the corresponding root meansquare errors of prediction set(RMSEP).66nd 0.37.Furthermore,a new genericPLS model was built based on the chalselected from the intervals of thethree SI-PLS models to identify the oil adulterantsardless of the adultrated oil types.Themodel achieved with Rp=0.9988 and RMSEP==1.52,These results indicated that the charac-teristic near infrared spectral regions could determine the level of adulteration in the camllia oil.

Effect of Characteristic Spectral Lines on Rock Identification of LIBS

The LIBS （Laser induced-breakdown spectroscopy） combined with BPNN （Back propagation neural network） was applied in rock sorting and distinguishing for 26 rock samples of 6 types. According to contents of major elements in samples, we selected lines of Si, Al, Fe, K, Ca, Mg, Na, Ti and Mn. These lines of 9 elements composed three characteristic spectral models which were the WSLM （Wide spectral line model）, the PM （Peak model） and the PRM （Peak ratio model）. The first and the second characteristic spectral model were divided into 9 kinds, as follows： the characteristic spectrum with 1 element, the characteristic spectrum with 2 elements, we can deduce the rest from this and the last one has 9 elements. The third model was divided into 8 kinds which were using AI as reference element. We analysed spectrums of the three models by BPNN. Experimental results shown that whether sorting or distinguishing these samples, identification accuracies of the PM were more than that of the PRM overall, the same as the WSLM did to the PM. While the selected number of elements was 5, 6 or 7, the identification accuracy of the WSLM could reach more than 90%. Continuing to add the number of elements to improve identification accuracy was not very obvious.

Primary Study on Microarc Oxidation of AZ91D

The magnesium has some excellent properties such as ligh quality, high specific strength and stiffness, high damp and reeoverd easily compared with steel, aluminium, engineering plastic. So the application and exploitation of magnesium arose extensive attention of the public.

Selection of characteristic spectral bands for the analysis by the NIR correlation coefficient method

We analyzed the infrared 0R）-near infrared （NIR） 2D correlation spectra of drugs perturbed by temperature. By identification of functional groups by IR spectrum and by the correlation analysis of IR-NIR spectrum, we identified the characteristic spectral bands that were closely related to the structure of a drug substance of interest. These characteristic spectral bands were relatively less interfered by other ingredients for analysis by the NIR correlation coefficient method. With these characteristic spectral bands, the accuracy of screening illegally added Sildenafil citrate, Tadalafil and Metforrnin hydrochloride in Chinese patent drugs and healthcare products reached about 90%, which met the requirements of rapid screening.

Non-destructive measurement of chlorophyll in tomato leaves using spectral transmittance

In this study,spectral transmittances were measured in the wavelength range from 300 nm to 1100 nm of tomato leaves with different chlorophyll contents and compositions,and the correlations between the spectral transmittances and the contents of chlorophyll a,chlorophyll b and total chlorophyll were analyzed.With the characteristic wavelengths of 560 nm,650 nm,720 nm and the reference wavelength of 940 nm,nine sets of characteristic spectral parameters were obtained.According to the results of correlation analysis and regression model exploration,characteristic spectral parameters of T940/T560,T940/T650 and log(T940/T560)among the nine sets of parameters were highly correlated to the estimated contents of chlorophyll a,chlorophyll b and total chlorophyll of tomato leaves.The relative errors of total chlorophyll and chlorophyll a/b ratio were(5.1±3.7)%and(4.9±4.3)%,respectively.Therefore,the above three characteristic spectral parameters could be applied in the rapid non-destructive estimation of the contents of chlorophyll a,chlorophyll b and total chlorophyll as well as chlorophyll a/b ratio of tomato leaves.

Targeted isolation and identification of bioactive pyrrolidine alkaloids from Codonopsis pilosula using characteristic fragmentation-assisted mass spectral networking

Codonopsis pilosula(CP),a well-known food medicine homology plant,is commonly used in many countries.In our preliminary study,a series of pyrrolidine alkaloids with high MS responses were detected as characteristic absorbed constituents in rat plasma after oral administration of CP extract.However,their structures were unclear due to the presence of various isomers and the lack of reference standards.In the present study,an MS-guided targeted isolation of pyrrolidine alkaloids of CP extract was performed by ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry(UPLC/Q-TOF MS).For data analysis under fast data directed acquisition mode(Fast-DDA),an effective approach named characteristic fragmentation-assisted mass spectral networking was successfully applied to discover new pyrrolidine alkaloids with high MS response in CP extract.As a result,seven new pyrrolizidine alkaloids[codonopyrrolidiums C–I(3–9)],together with two known ones(1 and 2),were isolated and identified by NMR spectral analysis.Among them,codonopyrrolidium B(1),codonopyrrolidium D(4)and codonopyrrolidium E(5)were evaluated for lipid-lowering activity,and they could improve high fructose-induced lipid accumulation in HepG2 cells.In addition,the characteristic MS/MS fragmentation patterns of these pyrrolizidine alkaloids were investigated,and 17 pyrrolidine alkaloids were identified.This approach could accelerate novel natural products discovery and characterize a class of natural products with MS/MS fragmentation patterns from similar chemical scaffolds.The research also provides a chemical basis for revealing in vivo effective substances in CP.

Fluorochrome-labeled monoclonal antibody with characteristic M-shaped spectral peak for optical imaging: Dual-labeling versus mixture of fluorochromes

In this work two different fluorochromes （Alexa 594 and Alexa 680） are conjugated to the same monoclonal antibody （Cetuximab） for obtaining a characteristic M-shaped dual-peak spectrum. Dual-labeling of Cetuximab by mixing both fluorochromes before the conjugation step gives spectral results similar to those of mixing of fluorochrome-labeled Cetuximab after the conjugation step （P 〉 0.05）. In conclusion, both methods may be used equivalently for producing a dual-labeled single-antibody probe. Future studies may test whether the M-shaped spectrum may increase the diagnostic confidence in tumor-targeted multispectral optical imaging.

Extraction of palaeochannel information from remote sensing imagery in the east of Chaohu Lake, China

Palaeochannels are deposits of unconsolidated sediments or semi-consolidated sedimentary rocks depos- ited in ancient, currently inactive river and stream channel systems. It is distinct from the overbank deposits of currently active river channels, including ephemeral water courses which do not regularly flow. We have introduced a spectral characteristics-based palaeochannel information extraction model from SPOT-5 imagery with special time phase, which has been built by virtue of an analysis of remote sensing mechanism and spectral characteristics of the palaeochannel, combined with its distinction from the spatial distribution and spectral features of currently active river channels, also with the establishment of remote sensing judging features of the palaeochannel in remote sensing image. This model follows the process of supervised classification → farmland masking and primary component analysis→ underground palaeochan- nel information extraction → information combination→ palaeochannel system image. The Zhegao River Valley in the east of Chaohu Lake was selected as a study area, and SPOT-5 imagery was used as a source of data. The result was satisfactory when this method has been successfully applied to extract the palaeochannel informa- tion, which can provide good reference for regional remote sensing archeology and neotectonic research. However, the applicability of this method needs to be tested further in other areas as the spatial characteristics and spectral response of palaeochannel might be different.

Phase-matched high-order harmonics by interaction of Ar atoms with high-repetition-rate low-energy femtosecond laser pulses

Phase-matched high-order harmonic generation in Ar gas-filled cell was investigated experimentally. We obtained phase-matched 27th order harmonic driven by a commercially available solid-state femtosecond laser system at 0.55 mJ/pulse energy level and 1 kHz repetition rate. To our knowledge, this is the lowest driving laser energy used to obtain phase-matched 27th order harmonic in a static gas cell. High-order harmonic generation at different gas density was studied systematically. Spectral blueshift and broadening of high harmonics under different pressure were analyzed. We found that the source size and spatial distribution of high-order harmonics are quite different under the phase-matching condition from those of the phase-mismatching case.