α-glucosidase inhibitory,antioxidant activity,and GC/MS analysis of Descurainia sophia methanolic extract: In vitro,in vivo,and in silico studies

Due to the presence of various phenolic compounds in D.sophia, this plant may have an inhibitory effect on α-Glc and ultimately diabetes control. Therefore, this work aims to scrutinize total phenolic, flavonoid contents, antioxidant capacity, and α-Glc inhibitory activity in aerial parts of methanolic D.sophia extract. The methanolic flower extracts were selected from among aerial parts for the experimental study of anti-diabetic effects by α-Glc inhibitory assays. The flower extracts were also studied by GC/MS to detect the compounds. The total phenolic and flavonoid contents were 21.38 ± 0.93 GAE/g and 96.2 ± 0.20 QE/g, respectively. The IC₅₀ value of flower extract for α-Glc inhibition with mixed (Competitive/non-competitive) mode was found to be 20.34 ± 0.11 mg/ml. Furthermore, in-vivo studies showed that the blood glucose level reduced after consumption of flower extract compared to the control group. Twenty-one compounds were identified by GC/MS technique. These compounds were assessed for high docking scores against α-Glc in silico. Docking score calculations exhibited that the DES-α-Glc complex had a significantly higher binding energy (-6.13 Kcal/mol) than other compounds. The DES-α-Glc complex which displayed a higher docking energy value than the ACR was subjected to MDs studies. The findings of this study suggest that the flower extract of D.sophia can be used as a suitable additive in syrups or foods with anti-diabetic capacity.     

Investigation on the relationship between leaf water use efficiency and physio-biochemical traits of winter wheat under rained condition

Different statistical methods and path analysis were used to study the relationship between leaf water use efficiency (WUE) and physio-biochemical traits for 19 wheat genotypes, including photosynthesis rate (P_n), stomatal conductance (g_s), transpiration rate (T_r), intercellular concentration of carbon oxide (C_i), leaf water potential (Ψ_w), leaf temperature, wax content, leaf relative water content (RWC), rate of water loss from excised-leaf (RWL), peroxidase (POD) and superoxide dismutase (SOD) activities. The results showed that photosynthesis rate, stomatal conductance and transpiration rate were the most important leaf WUE variables under rainfed conditions. Based on the results of five statistical analyses, it is reasonable to assume that high leaf WUE wheat under the rained could be obtained by selecting breeding materials with high photosynthesis rate, low transpiration rate and stomatal conductance.     

监测小麦叶片氮积累量的新高光谱特征波段及比值植被指数

实时、快速、无损监测作物氮素状况对于精确氮肥管理具有重要意义。传统的氮素估测方法在时间或空间上难以满足要求,新兴的高光谱遥感技术为作物氮素监测提供了有效手段和技术途径。本研究的目的是基于三个田间试验的系统观测资料,探索可用于小麦叶片氮素监测的新的高光谱敏感波段及比值指数。利用减量精细采样法,系统构建了350～2 500 nm范围内所有两两波段形成的比值光谱指数RSI(ratio spectral index),综合分析了小麦叶片氮积累量LNA(leaf nitrogen accumulation)(g N·m-2)与RSI的定量关系,发现了监测叶片氮积累量的新高光谱特征波段(990, 720)和光谱指数RSI(990, 720),建立了相应的监测模型y=5.095x-6.040,模型的决定系数(R2)为0.814。利用独立试验资料检验模型,决定系数(R2)为0.847,相对根均方差(RRMSE)为24.70%,表明模型预测值与观察值之间的符合度较高。因此,利用高光谱比值指数RSI(990, 720)来估算小麦叶片氮积累量是精确可行的。该结果为便携式小麦氮素监测仪的研制开发及遥感信息的快速提取提供了适用可行的波段选择与技术依据。     

Some remarks about leaf roots

Nishimura et al. [On graph powers for leaf-labeled trees, J. Algorithms 42 (2002) 69-108] define a k-leaf root of a graph G=(V_G,E_G) as a tree T=(V_T,E_T) such that the vertices of G are exactly the leaves of T and two vertices in V_G are adjacent in G if and only if their distance in T is at most k. Solving a problem posed by Niedermeier [Personal communication, May 2004] we give a structural characterization of the graphs that have a 4-leaf root. Furthermore, we show that the graphs that have a 3-leaf root are essentially the trees, which simplifies a characterization due to Dom et al. [Error compensation in leaf power problems, Algorithmica 44 (2006) 363-381. (A preliminary version appeared under the title “Error compensation in leaf root problems”, in: Proceedings of the 15th Annual International Symposium on Algorithms and Computation (ISAAC 2004), Lecture Notes in Computer Science, vol. 3341, pp. 389-401)] and also a related recognition algorithm due to Nishimura et al. [On graph powers for leaf-labeled trees, J. Algorithms 42 (2002) 69-108].     

Some new leaf normal-angle distribution models and their influence on geometry functions and area scattering phase functions related to radiative transfer problems in vegetative canopies

This note is devoted to the study of some new analytic leaf angle distribution models by a linear combination of idealized models primarily developed to study realistic light scattering processes for radiative transfer in a vegetative canopy medium.     

融合冠层水分特征的光谱参数NCVI及反演玉米LAI

精确反演农作物冠层叶面积指数对指导作物管理和作物估产具有非常重要的意义。以吉林市郊区玉米种植区为试点,考虑冠层叶片水分含量对LAI的贡献,在NDVI的基础上结合表征冠层叶片水分含量的植被指数DSWI,提出一种归一化综合植被指数NCVI,以此建立模型反演LAI,并对模型进行检验。结果表明:NCVI模型反演LAI值与实测值之间存在良好的对应关系,此模型突破了传统经验模型对稠密冠层LAI反演的局限,对LAI值大于3的冠层反演效果良好;另外,NCVI模型对土壤水环境十分敏感,在干旱半干旱地区的反演效果明显优于一般区域。     

枸杞叶中甜菜碱的提取

用正交试验比较固液比、浸提时间、浸提温度、超声时间对甜菜碱提取率的影响,选取的因素中,对柴达木枸杞叶甜菜碱提取率影响程度依次为：超声时间〉固液比〉浸提时间〉浸提温度。最佳提取工艺是固液比（g/mL）为1∶60,60℃,浸提4h,超声10m in。     

基于SVM与RF的苹果树冠LAI高光谱估测

叶面积指数(leaf area index,LAI)是反映作物群体大小的较好的动态指标。运用高光谱技术快速、无损地估测苹果树冠叶面积指数,为监测苹果树长势和估产提供参考。以盛果期红富士苹果树为研究对象,采用ASD地物光谱仪和LAI-2200冠层分析仪,在山东省烟台栖霞研究区,连续2年测量了30个果园90棵苹果树冠层光谱反射率及LAI值;通过相关性分析方法构建并筛选出了最优的植被指数;利用支持向量机(support vector machine, SVM)与随机森林(random forests, RF)多元回归分析方法构建了LAI估测模型。新建的GNDVI₅₂₇,NDVI₆₇₆,RVI₆₈₂,FD-NVI₆₅₆和GRVI₅₁₇五个植被指数及前人建立的两个植被指数NDVI₆₇₀和NDVI₇₀₅与LAI的相关性都达到了极显著水平;建立的RF回归模型中,校正集决定系数C-R2和验证集决定系数V-R2为0.920,0.889,分别比SVM回归模型提高了0.045和0.033,校正集均方根误差C-RMSE、验证集均方根误差V-RMSE为0.249,0.236,分别比SVM回归模型降低了0.054和0.058, 校正集相对分析误C-RPD、验证集相对分析误V-RPD达到了3.363和2.520,分别比SVM回归模型提高了0.598和0.262,校正集及验证集的实测值与预测值散点图趋势线的斜率C-S和V-S都接近于1,RF回归模型的估测效果优于SVM。RF多元回归模型适合盛果期红富士苹果树LAI的估测。     

基于机器学习和可见光光谱的冬小麦叶片氮积累量估算

在拔节期分4次采集了6个施氮水平下的冬小麦冠层图像,同步进行取样并以凯氏定氮法测定叶片含氮量,进而计算叶片氮积累量。利用随机森林算法分割冠层图像之后提取冠层覆盖度、可见光波段(R, G和B)三个分量及其衍生的5个色彩指数。以冠层覆盖度外加色彩指数、色彩分量的两种非线性回归,以及人工神经网络、支持向量回归、随机森林3种机器学习算法建立了冬小麦叶片氮积累量的估算模型。结果表明利用色彩指数的非线性回归模型的估算精度稍低于其他方法,而随机森林算法的拟合精度最高,但存在明显的过拟合现象。其他三种方法,即以冠层覆盖度及色彩分量为输入变量的非线性回归、支持向量回归和人工神经网络方法,均具有较高的拟合精度和泛化性能。     

常绿树叶自然衰老的红外光谱研究

应用傅里叶变换红外光谱技术对七种常绿树的幼叶、成叶和老黄叶进行了研究,以期探讨常绿树叶自然衰老的光谱规律。不同时期叶片红外光谱变化主要在1 800～700 cm-1范围,用吸光度比A_{1 070}/A_{2 927}和A_{1 070}/A_{1 160}考察叶样多糖相对含量变化,用A_{1 318}/A_{2 922}考察草酸钙相对含量变化,用1 800～1 500 cm-1范围拟合峰的峰高比H_{1 650}/H_{1 740}考察蛋白质相对含量变化。结果显示在自然衰老过程中蛋白质、糖类、草酸钙相对含量有变化,但不同种树变化规律不同,说明不同种树叶衰老过程中物质积累、动员规律不同。证明中红外光谱可用于植物衰老生理变化的研究。