Tritium incorporation into functional materials by applying OT- for- OH exchange reaction

In order to reveal (1) the behavior of the tritium-labeled hydroxyl group (i.e., OT group) and (2) the effect of temperature on the dissociation equilibrium of tritiated water, the OT-for-OH exchange reaction in a homogeneous system was observed (1) using ionexchange resins and HTO water, and (2) using hydrogen oxides and HTO water. Consequently, the following four conclusions were obtained: (1) The OT-for-OH exchange reaction occurred between each anion-exchange resin (or each metal hydroxide) and HTO water. (2) The higher the temperature is, the smaller the activity of both anion-exchange resin and metal hydroxide will be, and the activity of cation-exchange resin is large when the temperature is high. (3) The larger the degree of crosslinking in each Biorad AG1 resin is, the lower the activity of the resin will be. (4) The exchange rate for the OT-for-OH exchange reaction is small when the electronegativity of the metal ion in the metal hydroxide is large.     

Hydrolysis of rice bran oil using immobilized lipase in a stirred batch reactor

Candida cylindracea lipase was immobilized by adsorption on acid washed glass beads. It was observed that protein loading of the support depends on the size of the particle, with smaller particle containing higher amount of protein per unit weight. Initial reaction rate linearly varied up to enzyme concentration of 17.25 U/mL. Amount of free fatty acids produced was linearly proportional up to the enzyme loading of 1650 μg/g of bead. Achievement of chemical equilibrium took longer time in the case of less protein loading. Degree of hydrolysis was found to decrease in second and third consecutive batch operations on repeated use of immobilized lipase.     

Species constancy depends on plot size – a problem for vegetation classification and how it can be solved

Question: While it is well known that species richness depends on plot size, it is not generally recognised that the same must be true for constancy. Accordingly, many authors use varying plot sizes when classifying vegetation based on the comparison of constancies between groups of plots. We ask whether the constancy‐area relationship follows a general rule, how strong the effect of plot sizes is on constancies, and if it is possible to correct constancies for area. Location: For empirical evaluation, we use data from plant communities in the Czech Republic, Sweden and Russia. Methods: To assess the potential influence of differences in plot size on constancies, we develop a mathematical model. Then, we use series of nested plot species richness data from a wide range of community types (herbaceous and forest) to determine the parameters of the derived function and to test how much the shape of the constancy‐area relationship depends on taxa or vegetation types. Results: Generally, the constancy‐area relationship can be described by C (A)=1?(1?C₀)^{(A/A0)^d}, with C being constancy, A area, C₀ known constancy on a specific area A₀, and d a damping parameter accounting for spatial autocorrelation. As predicted by this function, constancies in plant communities always varied from values near 0% to near 100% if plot sizes were changed sufficiently. For the studied vegetation types, a two‐ to fourfold increase in plot size resulted in a change of conventional constancy classes, i.e. an increase of constancy by 20% or more. Conclusions: Vegetation classification, which largely relies on constancy values, irrespective of whether traditional or modern fidelity definitions are used, is strongly prone to distorting scale effects when relevés of different plot sizes are combined in studies. The constancy‐area functions presented allow an approximate transformation of constancies to other plot sizes but are flawed by idiosyncrasies in taxa and vegetation types. Thus, we conclude that the best solution for future surveys is to apply uniform plot sizes within a few a priori delimited formations and to determine diagnostic species only within these formations. Finally, we suggest that more detailed analyses of constancy‐area relationships can contribute to a better understanding of species‐area relationships because the latter are the summation of the first for all species.     

燕山地区访花昆虫多样性及其影响因子

为了解燕山地区访花昆虫的群落结构及与其生境类型、干扰程度、海拔之间的关系, 本文采用样线法和灯诱法于2019年、2020年每年的7-8月对该地区湿地、森林、灌丛、草地、农田5种生境, 不同海拔梯度(0-1,200 m)的访花昆虫进行了采集。共采集访花昆虫1,306头, 隶属7目44科153种, 其中鳞翅目昆虫物种数最多, 半翅目昆虫个体数最多。灌丛生境的访花昆虫多样性最高。在中低海拔200-400 m段, Shannon-Wiener多样性指数、Margalef丰富度指数和Simpson优势度指数均最高。双变量回归结果表明, Shannon-Wiener多样性指数和Margalef丰富度指数分别与最暖季降水量和年降水量显著正相关(P < 0.05)。冗余分析(redundancy analysis)结果表明, 环境因子显著影响访花昆虫多样性, 但不同测度之间存在一定差异。温度和湿度均与Pielou均匀度指数呈正相关, 与Shannon-Wiener多样性指数、Margalef丰富度指数和Simpson优势度指数呈负相关; 弱干扰和中干扰程度对访花昆虫多样性影响最小, 科学管理农牧活动是保护访花昆虫多样性的关键。     

Mass spectrometric and kinetic studies on slow progression of papain-catalyzed polymerization of l-glutamic acid diethyl ester

Papain polymerizes l-glutamic acid diethyl ester (Glu-di-OEt) regioselectively, resulting in the formation of poly (γ-ethyl α-l-glutamic acid) with various degrees of polymerization of less than 13. Reaction temperatures below 20 °C were appropriate for the reaction in terms of suppression of non-enzymatic degradation of Glu-di-OEt and an increase in the peptide yield, while the reaction was preceded by a pronounced induction period. Mass spectrometric analyses of the reaction conducted at 0 °C revealed that the accumulation of the initial dimerization product, l-glutamyl-l-glutamic acid triethyl ester (Glu-Glu-tri-OEt), was limited during the induction period, and that a sequential polymer derived from a further elongation of the dimer was the tetramer, but not the trimer. Kinetic analyses of acyl transfer reactions with Glu-di-OEt and Glu-Glu-tri-OEt as acyl acceptors and Nα-benzoyl-l-arginine ethyl ester as an acyl donor affirmed that Glu-Glu-tri-OEt bound more strongly than Glu-di-OEt both to the S- and S′-subsites of papain. Therefore, what occurred during the initial stage of the polymerization was interpreted as follows: the rate of the papain-catalyzed dimerization of Glu-di-OEt was extremely slow, once Glu-Glu-tri-OEt was initially synthesized it exclusively bound to the active site of papain, and then papain utilized the dimer in polymerization effectively rather than the monomer.