[Measurement of Soil Total Nitrogen Using Near Infrared Spectroscopy Combined with RCA and SPA].

Visible near spectra tecnnology was adopted to detect soil total nitrogen content. 394 soil samples were collected from Wencheng, Zhejiang province to be used for calibration model (n=263) and independent prediction set (n=131). Raw spectra and wavelength-reduced spectra with five different pretreatment methods (SG smoothing, SNV, MSC, 1st-D and 2nd-D) were compared to determine the optimal wavelength range and pretreatment method for analysis. The results with 5 different pretreatment methods were not improved compared to that both of full spectra PLS model and wavelength reduction spectra model. Spectral variable selection is an important strategy in spectrum modeling analysis, because it tends to parsimonious data representation and can lead to multivariate models with better performance. In order to simply calibration models, the wavelength variables selected by two different variable selection methods (i. e. regression coefficient analysis (RCA) and successive projections algorithm (SPA) were proposed to be the inputs of calibration methods of PLS, MLR and LS-SVM models separately. These calibration models were also compared to select the best model to predict soil TN. In total, 9 different models were built ahd the best results indicated that PLS, MLR and LS-SVM obtained the highest precision with determination coefficient of prediction R2(pre) =0. 81, RMSEP=0. 0031 and RPD=2. 26 based on wavelength variables selected by RCA (0. 0002) and SPA as inputs of models. SPA-MLR model and other three models based on 7 sensitive variables selected by RC using 0. 0002 regression coefficient threshold value obtained the best result with R2(pre), RMSEP and RPD as 0. 81, 0. 0031 and 2. 26. This prediction accuracy is classied to be very good. For all the models, it could be concluded that RCA and SPA could be very useful ways to selected sensitive wavelengths, and the selected wavelengths were effective to estimate soil TN. It is recommended to adopt SPA variable selection or RCA variable selection method with both linear and nonlinear calibration models for measurement of the soil TN using Vis-NIR spectroscopy technology, and wavelengths selection could be very useful to reduce collinearity and redundancies of spectra.

[Review of Crop Canopy Spectral Information Detection Technology and Methods].

Compared with the traditional chemical methods and the subjective visual ways for measuring plant physiology information indicators, the assessments of crop canopy information through spectral radiometer are more simple, rapid and accurate. The applications of different types of spectral radiometer, especially for international general used Cropscan multispectral radiometer, for predicting crop canopy leaf area index under different growth stage, biomass, nitrogen, chlorophyll and yield, and monitoring plant diseases and insect pests were summarized based on crop group information acquisition methods in recent years. The varity of vegetation indices (VIs) were concluded after comparing regression coefficients of related models among different crops. In general, the correlation coefficients of mathematical models were high and it can realize the crop detection of various kinds of physiological information. Besides, the combination of multispectral radiometer and other sensors can provide useful information to evaluate the status of crops growth, which is very important in practice.

Type I and type III collagen-platelet interaction: inhibition by type specific receptor peptides.

We have previously cloned and characterized a platelet receptor for type III collagen (47 kDa) from a human bone marrow cDNA phage library and defined two active peptides. We also cloned and characterized a platelet receptor for type I collagen (65 kDa) and defined an active peptide. Our objective was to study whether there is type specificity of these active peptides. We have engineered a mutant receptor clone by replacing one of the two active peptides of the platelet receptor for type III collagen with the active peptide of the platelet receptor for type I collagen. The replacement of an active peptide at the amino terminal end (rMIII) of the platelet receptor for type III collagen with the type I collagen active peptide was done without altering the hydrophilicity of the protein. This purified recombinant protein reacts with polyclonal anti-47-kDa and anti-65-kDa active peptide antibodies. The purified recombinant protein inhibits both types I and III collagen-induced platelet aggregation. This rMIII also inhibits the adhesion of washed platelets to rabbit aortic segments (natural matrix) in a dose-dependent manner. The chemically synthesized hybrid peptide of each active peptide of platelet type I and type III collagen receptors inhibits types I and III collagen-induced platelet aggregation in a dose-dependent manner. These results suggest that there is a type specific reactive site on platelets for type I and type III collagens.