Coxsackievirus B4 infection of spinal sympathetic ganglion

Summary Coxsackievirus B₄ infection of a spinal sympathetic ganglion of a squirrel monkey is described. Chromatolysis and neuronophagia were extensive. It is suggested that such viral sympathetic ganglial infections may be responsible for dysfunction of organ systems.Supported by the Cardiovascular Research Fund, the Rowell A. Billups Fund for Research in Heart Disease, the Feazel Laboratory and grant No. RR-00164-17 from the Animal Resources Branch, Division of Research Resources of NIH.     

Characteristics of dynamic membrane filtration: structure,operation mechanisms,and cost analysis

Dynamic membrane technology represents a promising substitution for conventional membrane bioreactor system,which owns the merits of flexible and comparably cheap materials,easy for backwash,good antifouling property,etc.It has been over half a century since the principle of dynamic membranes was first reported,whereas the development and popularization are still limited.This paper makes a review on characteristics of dynamic membranes,including development and application,mechanism,structure and materials,operation conditions,membrane fouling,dynamic membrane cleaning,and cost analysis,attempting to give clues on promotions and perspectives exhibited of this technology.     

Tracing the stepwise oxygenation of the Proterozoic ocean

Biogeochemical signatures preserved in ancient sedimentary rocks provide clues to the nature and timing of the oxygenation of the Earth's atmosphere. Geochemical data suggest that oxygenation proceeded in two broad steps near the beginning and end of the Proterozoic eon (2,500 to 542 million years ago). The oxidation state of the Proterozoic ocean between these two steps and the timing of deep-ocean oxygenation have important implications for the evolutionary course of life on Earth but remain poorly known. Here we present a new perspective on ocean oxygenation based on the authigenic accumulation of the redox-sensitive transition element molybdenum in sulphidic black shales. Accumulation of authigenic molybdenum from sea water is already seen in shales by 2,650 Myr ago; however, the small magnitudes of these enrichments reflect weak or transient sources of dissolved molybdenum before about 2,200 Myr ago, consistent with minimal oxidative weathering of the continents. Enrichments indicative of persistent and vigorous oxidative weathering appear in shales deposited at roughly 2,150 Myr ago, more than 200 million years after the initial rise in atmospheric oxygen. Subsequent expansion of sulphidic conditions after about 1,800 Myr ago (refs 8, 9) maintained a mid-Proterozoic molybdenum reservoir below 20 per cent of the modern inventory, which in turn may have acted as a nutrient feedback limiting the spatiotemporal distribution of euxinic (sulphidic) bottom waters and perhaps the evolutionary and ecological expansion of eukaryotic organisms. By 551 Myr ago, molybdenum contents reflect a greatly expanded oceanic reservoir due to oxygenation of the deep ocean and corresponding decrease in sulphidic conditions in the sediments and water column.     

Study of the varve record from Erlongwan maar lake, NE China, over the last 13 ka BP

In a sediment sequence from Erlongwan maar lake that spans the last 13 ka BP, two main varve types can be recognized： biogenic varves （from the present to -11.2 ka BP, 0-632 cm） and clastic varves （from -11.2 to -12.7 ka BP, 632-700 cm）. Based on the dominant types of algae contained in the sediment, the biogenic varves can be classified into dinocyst-biogenic varves （0-63 cm） and mixed （dinocyst and diatom）-biogenic varves （214-632 cm）. In this paper, the formation process and components of the varve are described, the possible reason for the types of varve changing throughout the record is discussed and a high-resolution varve chronology is established spanning the last 13 ka BP. Although further varve counting and error assessment are needed, the results presented here represent a solid foundation for studying the palaeoclimate record of Erlongwan maar lake.     

基于ANSYS与Workbench的雨棚结构有限元分析

以某桥梁工程中的人行道雨棚为研究对象,利用有限元软件ANSYS建立了雨棚结构的整体有限元简化模型,对其同时承受风载和雪载的状态进行了静力学分析,得到了它的整体变形和应力分布结果,并提取其整体结构的轴向力和弯矩,作为分析其柱脚的载荷.在Pro/E中建立了柱脚的三维实体模型并将其导入到Workbench中,利用Workbench对其进行加载分析,得到柱脚的变形和应力分布情况.结果表明该雨棚的整体结构和柱脚设计均满足强度和刚度要求.     

Peptide bond formation destabilizes Shine-Dalgarno interaction on the ribosome

The ribosome is a molecular machine that translates the genetic code contained in the messenger RNA into an amino acid sequence through repetitive cycles of transfer RNA selection, peptide bond formation and translocation. Here we demonstrate an optical tweezer assay to measure the rupture force between a single ribosome complex and mRNA. The rupture force was compared between ribosome complexes assembled on an mRNA with and without a strong Shine-Dalgarno (SD) sequence-a sequence found just upstream of the coding region of bacterial mRNAs, involved in translation initiation. The removal of the SD sequence significantly reduced the rupture force in complexes carrying an aminoacyl tRNA, Phe-tRNA(Phe), in the A site, indicating that the SD interactions contribute significantly to the stability of the ribosomal complex on the mRNA before peptide bond formation. In contrast, the presence of a peptidyl tRNA analogue, N-acetyl-Phe-tRNA(Phe), in the A site, which mimicked the post-peptidyl transfer state, weakened the rupture force as compared to the complex with Phe-tRNA(Phe), and the resultant force was the same for both the SD-containing and SD-deficient mRNAs. These results suggest that formation of the first peptide bond destabilizes the SD interaction, resulting in the weakening of the force with which the ribosome grips an mRNA. This might be an important requirement to facilitate movement of the ribosome along mRNA during the first translocation step.     

明代中后期风化刑法的衰落

明代中后期随着商品经济迅速发展,社会风气日益腐化,放纵声色之风败坏了社会风化,对旨在纯正社会风气的风化刑法形成剧烈冲击。这在同时期的世情文学作品中得到穷形尽相的描写,犯奸者法不追究、嫁娶违律蔚然成风、男风与寡妇改嫁已然成俗。但是法不责众、律外原情等因素致使规制男女性事、迎亲嫁娶、妇女守节的风化刑法对此束手无策,有些条文甚至成了具文,统治者利用刑法维护风化的目的落空,衰落之相可见一斑。     

基于自组装二氧化钛空穴阻挡层的高效钙钛矿太阳能电池

器件兼容功能层的自组装工艺是一种简单、可行和节能的策略。在介孔钙钛矿太阳能电池(perovskite solar cells, PSCs)中,致密的TiO₂膜起到空穴阻挡层的作用,而介孔的TiO₂膜起到电子传输层的作用。然而,这两层通常都要通过高温退火法获得。在此,我们通过室温自组装工艺沉积了致密的TiO₂薄膜,以作为PSCs有效的空穴阻挡层。通过沉积时间控制致密TiO₂薄膜的厚度。优化致密TiO₂薄膜的厚度(80 nm),有无空穴传输层的介孔PSCs的能量转化效率分别为17.95%和10.66%。值得注意的是,基于自组装TiO₂的全低温PSCs显示出16.41%的能量转化效率。     

Production and characterization of antibodies cross-reactive with major aflatoxins

Antibodies cross-reactive with 4 major aflatoxins were demonstrated three weeks after immunization of rabbits with an immunogen which was prepared by conjugating aflatoxin B₃ to bovine serum albumin. Aflatoxin B₃ was first converted to its hemisuccinate before conjugation to the protein. Tritiated aflatoxin B₁ (AFB₁) was used as the marker ligand both for antibody titer determination as well as for analysis of antibody specificity. Competitive RIA revealed that the antibodies have good cross-reactivity with aflatoxins B₁, B₂, G₁, and G₂ when tritiated AFB₁ was used as the marker ligand. The concentrations causing 50% inhibition of binding of³H-AFB₁ to the antibodies by unlabeled aflatoxins B₁, B₂, G₁, G₂ and B₃ were found to be 0.25, 3.34, 0.32, 4.0 and 0.53 ng/assay, respectively. The antibodies could be used for simultaneous analysis of aflatoxins B₁ and G₁, two of the most important toxic metabolites produced byAspergillus flavus andA. parasiticus.