[Analysis and estimation of the phosphorus content in cucumber leaf in greenhouse by spectroscopy].

A handheld spectroradiometer was used to measure the spectral reflectance of the crop with the measurable range from 325 nm to 1075 nm. Since the first derivative of the spectra can well eliminate spectral error, it was calculated for each spectrum. The cucumber leaves were also sampled and the phosphorus content was measured for each sample with chemical method. First, the correlation between the phosphorus content of the cucumber leaf and the spectral reflectance was analyzed but high coefficient was not obtained. It was shown that there is not high linear relation between those. Then, the analysis was conducted between the phosphorus content of the cucumber leaf and the first derivative of spectrum for each sample. The coefficients were improved. However, it was not high enough to establish an estimation model. It shows that non-linear model is needed to estimate the phosphorus content of the crop leaf based on spectral reflectance. Artificial neural network (ANN) and support vector machine (SVM), the modern ealgorithm for modeling and estimating, were used to establish the nonlinear models. From stepwise multi-regression, four wavelengths, 978, 920, 737 and 458 nm, were selected as modeling wavebands. For the Artificial Neural Network (ANN) model, the data of spectral reflectance in the four wavebands were taken as the input and the phosphorus content was taken as the output. And the number of the neurons in the middle layer, the learning rate, and the learning error were set as 25, 0.05, and 0.001, respectively. The calibration accuracy of the model was 0.995, and the validation accuracy reached to 0.712. For the Support Vector Machine (SVM) model, the selected kernel function was anova, and the penalty parameter C and the linear epsilon-insensitive loss function were set as 100 and 0.00001, respectively. The calibration accuracy of the model was closed to 1, and the validation accuracy reached to 0.754. It can be concluded that both nonlinear models are practical.

[New method and instrument to diagnose crop growth status in greenhouse based on spectroscopy].

Spectral reflectance of cucumber leaves in greenhouse was measured using an ASD FieldSpec Pro VNIR spectrometer with natural illumination. Two sensitive wavelengths, 527 nm and 762 nm, were selected to evaluate the nitrogen content of the cucumber leaves. A model was established and validated using normal difference color index(NDCI) with the correlation coefficient of 0.881. Based on the above efforts, a handheld spectral instrument was developed to diagnose the growth status of the crop in greenhouse using fiber optics. The instrument was mainly composed of four parts: reflected light acquisition system, light intensity measurement unit, signal conditioning unit, and data acquisition system. The sunlight reflected by the crop was transmitted by the fiber, and passed through the light filter to obtain light at the sensitive wavelengths. Finally it was transformed into electronic signal by the photoelectric transistor, and was used to diagnose the growth status of the crop according to the evaluation model. The result showed that the developed instrument was practical.

[Real-time analysis of soil moisture, soil organic matter, and soil total nitrogen with NIR spectra].

The grey-brown alluvial soil in northern China was selected as research object, and the feasibility and possibility of real-time analyzing soil para-fueter with NIR spectroscopic techniques were explored. One hundred fifty samples were collected from a winter wheat farm. NIR absorbance spectra were rapidly measured under their original conditions by a Nicolet Antaris FT-NIR analyzer. Three soil parameters, namely soil moisture, SOM (soil organic matter) and TN (total nitrogen) content, were analyzed. For soil moisture content, a linear regression model was available, using 1920 nm wavelength with correlation coefficient of 0.937, so that the results obtained could be directly used to real-time evaluate soil moisture. SOM content and TN content were estimated with a muviaiple linear regression model, 1870 and 1378 nm wavelengths were selected in the SOM estimate model, and 2262 and 1888 nrameter wavelengths were selected in the TN estimate model. The results showed that soil SOM and TN contents can be evaluated by using NIR absorbance spectra of soil samples.

Stereoselectivity in renal clearance of trans-tramadol and its active metabolite, trans-O-demethyltramadol.

AIM: To study the stereoselectivity in renal clearance of trans-tramadol and its active metabolite, trans-O-demethyltramadol. METHODS: The right kidneys were isolated from male SD rats and perfused with 100 mL of perfusate medium containing trans-tramadol 300 microg/L or trans-O-demethyltramadol 50 microg/L. After perfusion, the concentrations of the enantiomers of trans-tramadol and trans-O-demethyltramadol in the perfusate and urine were determined by high performance capillary electrophoresis. The enantiomeric ratios were calculated. RESULTS: After the kidneys being perfused with trans-tramadol hydrochloride, the concentration of (+)-trans-tramadol was higher than that of (-)-trans-tramadol, and the concentration of (+)-trans-O-demethyltramadol was lower than that of (-)-trans-O-demethyltramadol in the perfusate; meanwhile, (+)-trans-tramadol was more than (-)-trans-tramadol, and (+)-trans-O-demethyltramadol was less than (-)-trans-O-demethyltramadol in the urine. After the kidneys being perfused with trans-O-demethyltramadol, the concentration of (+)-trans- O-demethyltramadol was lower than that of (-)-trans-O-demethyltramadol in the perfusate, and (+)-trans-O-demethyltramadol was more than (-)-trans-O-demethyltramadol in the urine. CONCLUSION: The renal clearance of trans-tramadol was stereoselective. The O-demethylation of trans-tramadol was stereoselective in the kidneys, (-)-trans-tramadol being preferentially metabolized. The renal clearance of trans-O-demethyltramadol was also stereoselective, the (+)-enantiomer being preferentially cleared into the urine.