Stereological estimation of surface area and barrier thickness of fish gills in vertical sections

Previous morphometric methods for estimation of the volume of components, surface area and thickness of the diffusion barrier in fish gills have taken advantage of the highly ordered structure of these organs for sampling and surface area estimations, whereas the thickness of the diffusion barrier has been measured orthogonally on perpendicularly sectioned material at subjectively selected sites. Although intuitively logical, these procedures do not have a demonstrated mathematical basis, do not involve random sampling and measurement techniques, and are not applicable to the gills of all fish. The present stereological methods apply the principles of surface area estimation in vertical uniform random sections to the gills of the Brazilian teleost Arapaima gigas. The tissue was taken from the entire gill apparatus of the right‐hand or left‐hand side (selected at random) of the fish by systematic random sampling and embedded in glycol methacrylate for light microscopy. Arches from the other side were embedded in Epoxy resin. Reference volume was estimated by the Cavalieri method in the same vertical sections that were used for surface density and volume density measurements. The harmonic mean barrier thickness of the water‐blood diffusion barrier was calculated from measurements taken along randomly selected orientation lines that were sine‐weighted relative to the vertical axis. The values thus obtained for the anatomical diffusion factor (surface area divided by barrier thickness) compare favourably with those obtained for other sluggish fish using existing methods.     

Analytical TEM study of annealed nanocrystalline cobalt–phosphorous electrodeposits

Investigation of thermal stability of two nanocrystalline Co–P alloys shows that P atoms segregate to the grain boundaries upon annealing until precipitation of Co₂P and CoP precipitates takes place. The P-rich precipitates formed have been investigated by analytical transmission electron microscopy to obtain statistical results of precipitate size, volume fraction and spatial distribution. Electron spectroscopic imaging maps show that the P-rich precipitates are 33 ± 9 nm in Co–1.1at.%P and 33 ± 12 nm in Co–3.2at.%P. The main differences between the alloys are the precipitate size distribution (Co–3.2at.%P having broader distribution) and precipitate volume number density (Co–3.2at.%P has 1.8 times more precipitates than Co–1.1at.%P). The volume fraction of precipitates is 3.0% in Co–1.1at.%P and 4.4% in Co–1.1at.%P. Most of the precipitates are of nearly spherical or slightly elongated shape, and only a few have a platelet-like shape as expected from previous tomographic atom probe measurements. Due to the truncation and projection effects, the composition of the precipitates could not be determined.     

分布式环境下全局序列模式挖掘技术研究

由于分布式环境下挖掘全局序列模式常常产生过多候选序列,加大了网络通信代价.为此提出一种基于分布式环境下的全局序列模式快速挖掘算法.该算法将各站点得到的局部序列模式压缩到一种语法序列树上,避免了重复的序列前缀传输;基于合并树中节点序列规则和简单的特点,提出一种项扩展和序列扩展剪枝策略,有效地约减了候选序列,减少了网络传输量,从而快速生成全局序列模式.理论和实验表明,在大数据集环境下该算法性能优越,能够有效地挖掘全局序列模式.     

Leaf blade anatomy and ultrastructure of six <i>Simira</i> species (Rubiaceae) from the Atlantic Rain Forest,Brazil

Simira is a predominantly woody Neotropical genus comprising 41 taxa, 16 of which occur in Brazil and eight of them in the southeastern region of Brazil. Leaf blades of Simira eliezeriana Peixoto, S. glaziovii (K. Schum.) Steyerm., S. grazielae Peixoto, S. pikia (K. Schum.) Steyerm., S. rubra (Mart.) Steyerm., S. sampaioana (Standl.) Steyerm. were collected in the southeastern region of Brazil and fixed according to usual methods for light and electron microscopy. The leaf blades show typical characteristics of the Rubiaceae family as dorsiventral mesophyll and paracytic stomata. The presence of two bundle sheaths that extend to the upper epidermal layer, prismatic crystal and crystal-sand, alkaloids in the mesophyll and the organization micromorphological of the outer periclinal wall are considered characteristics representative for the genus. This study also demonstrates some leaf blade characteristics that can be used to Simira species identification (leaf surface, domatia types, epicuticular wax types and patterns of epidermis anticlinal cell walls).     

Effects of substitutions in the binding surface of an antibody on antigen affinity

The interactions between the Fab and single-chain Fv (scFv) fragments of an antibody (NC10) and its antigen, influenza virus neuraminidase, were analysed in the crystal structures of the Fab-neuraminidase and scFv-neuraminidase complexes. To investigate the contribution to binding made by cavities, salt links and hydrogen bonds in the antibody- antigen interface, 14 single amino acid replacements were made at six contact residues in the scFv fragment by site-directed mutagenesis. The binding affinity of each mutant scFv antibody for neuraminidase was determined with a BIAcore optical biosensor. Four of the mutations resulted in large changes in the free energy of binding to neuraminidase (deltadeltaG > 1 kcal/mol) and together may account for approximately 70% of the free energy of binding. Hence these data support the theory that a small number of residues form the 'functional epitope' and are most important for binding of NC10 to neuraminidase. The salt link between antibody residue (Asp)H56 and (Lys)N432 from neuraminidase was demonstrated to be important for affinity, since substitution of (Asp)H56 with Asn caused a large reduction in the free energy of binding (deltadeltaG = +2.8 kcal/mol). Hydrogen bonds provided by (Tyr)L32 and (Asp)H56 were also important for binding: mutation of (Tyr)L32 to Phe resulted in a significant reduction in binding affinity (deltadeltaG = +1.7 kcal/mol). Disruption of hydrophobic interactions (van der Waals contacts) led to significant reductions in affinity also ((Tyr)H99 to Ala, deltadeltaG = +1.5 kcal/mol; (Leu)L94 to Ala, deltadeltaG > +3.0 kcal/mol). An attempt to increase binding affinity by filling a cavity in the interface with a larger antibody side chain was unsuccessful, as the free energy gained by new antibody-antigen interactions did not compensate for the removal of cavity-bound water molecules.      

城市化背景下城市规划与产业规划的互动关系

以江苏省近20年来的城市化进程为背景,通过城市规划与产业规划互动发展的研究,以此来研究城市规划与产业规划是否存在先导性与推动性、相容性与相背性以及协调性和互动性关系,为确保城市化背景下的城市和产业良性发展提供理论依据。     

生态城市发展与建设模式

通过对生态城市概念的提出、理论渊源以及不同时期定义的回顾,提出生态城市是结构合理、功能高效、关系和谐,且存在与发展状态皆优的,可持续发展的现代化城市;将国外生态城市建设模式划分为规划调控型．环境美化型、污染治理型．资源循环型以及功能转化型五大类型,并通过案例分析介绍其成功经验;分析我国生态城市建设的不同阶段,并根据其不足,提出重建“近自然型“城市生态系统可为循环和谐型生态城市的建设打下基础。     

关于"经评审合理最低价决标方式"的分析与研究

文章通过对低价中标的优缺点的介绍,以及对影响低价中标有效实施的主要影响因素进行了分析,提出了充分发挥低价中标优势避免负面影响的对策.     

超滤技术在无锡中桥水厂深度处理工程中的应用

近年来,膜处理技术在水处理领域的应用已趋成熟。随着对供水安全的日益关注,超滤技术在饮用水处理领域中得到越来越广泛的应用。无锡市自来水总公司中桥水厂于2009年采用西门子外压式超滤膜处理技术,率先建成15×104m3/d采用超滤膜饮用净水处理系统,出水水质全面达到且部分优于《生活饮用水卫生标准》(GB 5749—2006)。根据无锡中桥水厂升级改造工程的经验以及两年多的实际运行情况,分析了超滤系统运行操作的特点。超滤技术在无锡中桥水厂的应用可以为国内其他水厂的工艺升级改造,特别是大型水厂的膜法水处理工程项目的决策和建设提供参考。