关于群落的相似系数

本文讨论了植物生态学中由Jaccard(1912)和Sφrensen(1948)等人相继提出的关于群落的相似系数之间的关系,并分析了它们的合理性,例如,我们指出,由Motyka定义的系数和Renkonen(1938)的生态位的相似系数是一致的,而Spatz(1970)根据Motyka的原理推导的相似系数是不合理的。最后,我们指出,作者和杨义群(1982)提出的关于生态位的相似系数同样可以用来度量植物群落的相似性,这是一种很恰当的度量。     

Psychrotolerant Mesorhizobium sp. Isolated from Temperate and Cold Desert Regions Solubilizes Potassium and Produces Multiple Plant Growth Promoting Metabolites

Soil potassium (K) supplement depends intensively on the application of chemical fertilizers, which have substantial harmful environmental effects. However, some bacteria can act as inoculants by converting unavailable and insoluble K forms into plant-accessible forms. Such bacteria are an eco-friendly approach for enhancing plant K absorption and consequently reducing utilization of chemical fertilization. Therefore, the present research was undertaken to isolate, screen, and characterize the K solubilizing bacteria (KSB) from the rhizosphere soils of northern India. Overall, 110 strains were isolated, but only 13 isolates showed significant K solubilizing ability by forming a halo zone on solid media. They were further screened for K solubilizing activity at 0 °C, 1 °C, 3 °C, 5 °C, 7 °C, 15 °C, and 20 °C for 5, 10, and 20 days. All the bacterial isolates showed mineral K solubilization activity at these different temperatures. However, the content of K solubilization increased with the upsurge in temperature and period of incubation. The isolate KSB (Grz) showed the highest K solubilization index of 462.28% after 48 h of incubation at 20 °C. The maximum of 23.38 µg K/mL broth was solubilized by the isolate KSB (Grz) at 20 °C after 20 days of incubation. Based on morphological, biochemical, and molecular characterization (through the 16S rDNA approach), the isolate KSB (Grz) was identified as Mesorhizobium sp. The majority of the strains produced HCN and ammonia. The maximum indole acetic acid (IAA) (31.54 µM/mL) and cellulase (390 µM/mL) were produced by the isolate KSB (Grz). In contrast, the highest protease (525.12 µM/mL) and chitinase (5.20 µM/mL) activities were shown by standard strain Bacillus mucilaginosus and KSB (Gmr) isolate, respectively.     

微量元素在尘肺患病率不同电厂的比较研究

为了调查微量元素对电厂尘肺患病率（甲厂〉乙厂）的影响,分别用中子活化法和原子吸收法测定两电厂粉尘、排放水和职工头发中化学元素含量,用邻苯三酚自氧化法测定接尘人员血中ＳＯＤ,结果发现甲厂粉尘中Ｖ、Ｃｒ、Ｃｏ、Ｍｎ和稀土元素含量比乙厂高,有显著性意义;乙厂比甲厂高的元素有Ｚｎ、Ｓｅ、Ａｓ、Ｂａ,而Ｎｉ、Ｃｄ未见显著性差异。甲厂工业排放水中Ｃｒ电明显高于乙厂。提示Ｖ、Ｃｒ、Ｃｏ、Ｍｎ和稀土元素对尘肺的形     

200 years of practical electroanalytical chemistry: past, present and future directions illustrated by reference to the on-line, on-stream and off-line determination of trace metals in zinc plant electrolyte by voltammetric and potentiometric techniques

The millennium being celebrated this year coincides with the 200th anniversary of the birth of practical electrochemistry made possible via Volta’s publication of the battery in the year 1800. The analytical chemists at the beginning of the 19th century were very quick to take advantage of this newly reported device and the first qualitative electrochemical determination of copper rapidly followed this pioneering discovery. In the last 200 years, electrochemical analysis, in its various forms, has been undertaken routinely in countless laboratories all over the world. However, in view of the long and distinguished history of the discipline, and some limitations that have been identified at the time of the celebration of the millennium, electrochemical analysis is regarded in some quarters as being a mature and conservative discipline whose importance in the future, when faced with severe competition from newly emerging alternative analytical techniques, is somewhat unclear. In this paper, an overview of past and present developments in electroanalytical chemistry and the possible future status of the technique is presented. In particular, emphasis is given to describing applications relevant to the also very mature field of electrowinning of zinc from plant electrolyte. This overview encompasses the author’s 25 years’ experience in developing polarographic, stripping voltammetric, adsorptive stripping voltammetric and ion-selective electrode (ISE) methods of analysis in on-line, on-stream and off-line modes for the determination of elements such as Cd, Pb, Ge, Sb (oxidation states (III) and (V)), Co, Ni, Zn, Fe, (oxidation states (II) and (III)), Tl, As (total) and Cu in zinc plant electrolyte. Developments that may contribute to an important future for analytical voltammetry are also considered as are limitations that could inhibit the extent of practical use of these electroanalytical techniques in the 21st century.     

Dynamic simulation and parametric influence analysis on thermal performance of a quartz tube solid particle receiver in solar tower power plants

Due to a higher operating temperature (≥800 °C), Solar Particle Receiver (SPR) which uses particles as the working medium is considered as one of best candidates to improve the thermoelectric conversion efficiency of concentrating solar power plants. In this paper, a quartz tube solid particle receiver model is fully developed by using the discretized lumped parameter method, in which the calculation process of particle temperature and thermal loss is clearly given. In order to improve the manipulation level of particle receiver during the operation, the dynamic characteristics of the quartz tube particle receiver are comprehensively studied by the disturbance test of selected input parameters. Besides, in order to grasp the influence rule of key parameters on the thermal performance of particle receiver, the key parameters’ sensitivity analysis is also deeply studied. The results show that the particle outlet temperature can reach as high as 810 °C under a relatively small value of solar flux 600 kW/m², but the receiver efficiency is only about 75%; Besides, the receiver efficiency shows a variation tendency that it rises first falls afterwards with the increase of incident solar flux. The validity of proposed model is verified by a heating experimental system with a single quartz tube, and the relative error is not more than 7.9%. The research results are beneficial for understanding the dynamic characteristics and designing the particle receiver.     

The Crystal Structure of Hop‐17(21)‐en‐3β‐yl acetate of Pluchea pteropoda Hemsl. from Vietnam

The title compound isolated from the roots of a Vietnamese plant and being known for its activity against fever was identified by this X‐ray analysis to be a pentacyclic triterpene of hopanoide type with a C17=C21 endocyclic double bond in the five membered ring. The presence of several axially substituted methyl groups on both the α and β side causes the so called "mid‐molecule strain" having already been reported in the literature for other hopane type ring systems.     

Crystal and Molecular Structure of Desmodin

The crystal structure of the title compound has been determined from X‐ray diffraction. The compound crystallizes from benzene in the orthorhombic system, space group P2₁2₁2₁, with unit cell parameters: a = 8.485(2), b = 9.816(2), c = 22.597(4) Å, Z = 4, V = 1881.9(7) ų. The structure was determined by direct methods and refined to a final R‐factor of 0.04. Six membered rings B and E are planar. Ring A and ring C are in slightly distorted sofa conformation. Ring D is in envelope conformation. The structure is stabilised by weak intermolecular C‐H...O hydrogen bonds.     

Fungicidal Activity of Recombinant Javanicin against Cryptococcus neoformans Is Associated with Intracellular Target(s) Involved in Carbohydrate and Energy Metabolic Processes

The occurrence of Cryptococcus neoformans, the human fungal pathogen that primarily infects immunocompromised individuals, has been progressing at an alarming rate. The increased incidence of infection of C. neoformans with antifungal drugs resistance has become a global concern. Potential antifungal agents with extremely low toxicity are urgently needed. Herein, the biological activities of recombinant javanicin (r-javanicin) against C. neoformans were evaluated. A time-killing assay was performed and both concentration- and time-dependent antifungal activity of r-javanicin were indicated. The inhibitory effect of the peptide was initially observed at 4 h post-treatment and ultimately eradicated within 36 to 48 h. Fungal outer surface alteration was characterized by the scanning electron microscope (SEM) whereas a negligible change with slight shrinkage of external morphology was observed in r-javanicin treated cells. Confocal laser scanning microscopic analysis implied that the target(s) of r-javanicin is conceivably resided in the cell thereby allowing the peptide to penetrate across the membrane and accumulate throughout the fungal body. Finally, cryptococcal cells coped with r-javanicin were preliminarily investigated using label-free mass spectrometry-based proteomics. Combined with microscopic and proteomics analysis, it was clearly elucidated the peptide localized in the intracellular compartment where carbohydrate metabolism and energy production associated with glycolysis pathway and mitochondrial respiration, respectively, were principally interfered. Overall, r-javanicin would be an alternative candidate for further development of antifungal agents.     

Recent Advances on the Development of Protein-Based Adhesives for Wood Composite Materials—A Review

The industrial market depends intensely on wood-based composites for buildings, furniture, and construction, involving significant developments in wood glues since 80% of wood-based products use adhesives. Although biobased glues have been used for many years, notably proteins, they were replaced by synthetic ones at the beginning of the 20th century, mainly due to their better moisture resistance. Currently, most wood adhesives are based on petroleum-derived products, especially formaldehyde resins commonly used in the particleboard industry due to their high adhesive performance. However, formaldehyde has been subjected to strong regulation, and projections aim for further restrictions within wood-based panels from the European market, due to its harmful emissions. From this perspective, concerns about environmental footprint and the toxicity of these formulations have prompted researchers to re-investigate the utilization of biobased materials to formulate safer alternatives. In this regard, proteins have sparked a new and growing interest in the potential development of industrial adhesives for wood due to their advantages, such as lower toxicity, renewable sourcing, and reduced environmental footprint. This work presents the recent developments in the use of proteins to formulate new wood adhesives. Herein, it includes the historical development of wood adhesives, adhesion mechanism, and the current hotspots and recent progress of potential proteinaceous feedstock resources for adhesive preparation.     

基于均匀设计优化深山草莓花瓣离体培养及植株再生体系

应用均匀设计法对深山草莓花瓣诱导愈伤组织和愈伤组织再分化芽苗的主要因子和水平进行了探讨.结果表明,深山草莓花瓣愈伤组织诱导的适宜培养基为LS+TDZ 2.06 mg.L-1+2,4-D 0.60 mg.L-1,诱导率为98%;愈伤组织再分化芽苗的适宜培养基为1/2 LS+TDZ 2.30 mg.L-1+NAA 0.10 mg.L-1+KT1.30 mg.L-1,分化率为96.3%.炼苗移栽后观察植株的形态、花、果及生长等特征,以筛选具有优良性状的株系.