High diversity of unknown picorna-like viruses in the sea

Picorna-like viruses are a loosely defined group of positive-sense single-stranded RNA viruses that are major pathogens of animals, plants and insects. They include viruses that are of enormous economic and public-health concern and are responsible for animal diseases (such as poliomyelitis), plant diseases (such as sharka) and insect diseases (such as sacbrood). Viruses from the six divergent families (the Picornaviridae, Caliciviridae, Comoviridae, Sequiviridae, Dicistroviridae and Potyviridae) that comprise the picorna-like virus superfamily have the following features in common: a genome with a protein attached to the 5' end and no overlapping open reading frames, all the RNAs are translated into a polyprotein before processing, and a conserved RNA-dependent RNA polymerase (RdRp) protein. Analyses of RdRp sequences from these viruses produce phylogenies that are congruent with established picorna-like virus family assignments; hence, this gene is an excellent molecular marker for examining the diversity of picorna-like viruses in nature. Here we report, on the basis of analysis of RdRp sequences amplified from marine virus communities, that a diverse array of picorna-like viruses exists in the ocean. All of the sequences amplified were divergent from known picorna-like viruses, and fell within four monophyletic groups that probably belong to at least two new families. Moreover, we show that an isolate belonging to one of these groups is a lytic pathogen of Heterosigma akashiwo, a toxic-bloom-forming alga responsible for severe economic losses to the finfish aquaculture industry, suggesting that picorna-like viruses are important pathogens of marine phytoplankton.     

Microscopic electronic inhomogeneity in the high-Tc superconductor Bi2Sr2CaCu2O8+x

The parent compounds of the copper oxide high-transition-temperature (high-Tc) superconductors are unusual insulators (so-called Mott insulators). Superconductivity arises when they are 'doped' away from stoichiometry. For the compound Bi2Sr2CaCu2O8+x, doping is achieved by adding extra oxygen atoms, which introduce positive charge carriers ('holes') into the CuO2 planes where the superconductivity is believed to originate. Aside from providing the charge carriers, the role of the oxygen dopants is not well understood, nor is it clear how the charge carriers are distributed on the planes. Many models of high-Tc superconductivity accordingly assume that the introduced carriers are distributed uniformly, leading to an electronically homogeneous system as in ordinary metals. Here we report the presence of an electronic inhomogeneity in Bi2Sr2CaCu2O8+x, on the basis of observations using scanning tunnelling microscopy and spectroscopy. The inhomogeneity is manifested as spatial variations in both the local density of states spectrum and the superconducting energy gap. These variations are correlated spatially and vary on the surprisingly short length scale of approximately 14 A. Our analysis suggests that this inhomogeneity is a consequence of proximity to a Mott insulator resulting in poor screening of the charge potentials associated with the oxygen ions left in the BiO plane after doping, and is indicative of the local nature of the superconducting state.     

热轧辊堆焊层成份,组织对其热疲劳和耐磨性能的影响

研究了复合式热轧辊五种典型堆焊层成份及组织对其抗热疲劳性和耐磨性的影响,并从中寻求出了能满足热轧辊工作要求的最佳成份及相应的最佳组织结构。     

硫脲基螯合树脂的合成及其对Ag(Ⅰ)的吸附性能

经预处理的花生壳颗粒(20～60目)与环氧氯丙烷接枝,引入活泼氯;活泼氯被硫脲取代后,成为硫脲基螯合树脂。最佳工艺条件;(1)合成醚化颗粒,反应时间为4h,反应温度为90℃;(2)取代引入硫脲基,反应温度及时间分别为90℃和2h。在溶液pH=5.4～5.8时,螯合树脂对Ag(I)的吸附容量为100mg/g。     

不同养殖方式的鱼池生态经济效益分析

分析了不同养殖方式鱼池的生态经济效益，结果表明：（１）进行不同养殖方式的畜禽联合养殖的鱼池，其生态经济价均高于对照池；（２）水产养殖要增产增收，不仅要提高物质和能量的利用率，而且与整个鱼池投入的科学性、合理性及投入的总水平有关。从作者所做的Ｂ号实验池结果来看，只有把两个方面很好地结合起来，才能获得比较全面的经济效益。     

用数值方法研究面积井网系统的扫油效率

本文应用三维三相黑油模型对等厚均质水平地层在不同流度比下,不同注入速度下,对五点系统、七点系统、直线排状系统及交错排状系统的面积扫油效率进行了系统计算。计算结果表明,井网系统不同,同一流度比下,面积波及系数也不同。五点系统最高,依次为交错排状、直线系统和七点系统。在不利流度比下,驱替的不稳定过程对五点和七点系统的波及系数的影响小于对交错排状和直线排状系统。当流度比从0.2增加至10时,波及系数急剧下降。当流度比进一步增大时,其递减速度减缓。见水后继续注水,面积波及系数可继续增大,直至地层全部水浸。在同一流度比下,含水率小于50％时,随着含水率的上升,面积波及系数增加缓慢。但当含水率高于60％时,随着含水的上升而急剧地增加。文中根据计算结果得出了不同井网条件下,不同注入孔隙体积倍数(或不同含水)时,波及系数与流度比的关系曲线,由这些曲线构成的图版可以用来进行注水井网动态过程的计算和确定油藏采收率。     

Areas in the amygdala necessary to the operation of the vagosympathetic pressor reflex

Summary Lesions of portions of the basal and cortical amygdaloid nuclei and the stria terminalis reversed or abolished arterial pressor responses to ipsilateral centripetal vagal stimulation (CVS). Destruction of these particular limbic structures in the rat did not affect cardiopulmonary responses to CVS.     

Acetylcholine activates an inward current in single mammalian smooth muscle cells

Acetylcholine, the major excitatory neurotransmitter to the smooth muscle of mammalian intestine, is known to depolarize smooth muscle cells with an apparent increase in membrane conductance. However, the ionic mechanisms that are triggered by muscarinic receptor activation and underlie this response are poorly understood, due in part to the technical problems associated with the electrophysiological study of smooth muscle. The muscarinic action of acetylcholine in certain neurones has been shown to involve the switching off of a resting K+ current (M-current) and a similar mechanism has recently also been identified in smooth muscle of amphibian stomach. We have now applied the patch-clamp technique to single smooth muscle cells of rabbit jejunum and find that muscarinic receptor activation switches on a nonselective, voltage-sensitive inward current. In addition, acetylcholine activates and then suppresses spontaneous K+ current transients, which are probably triggered by rises in intracellular Ca2+ in these cells.     

美国Wallapai矿区Mineral Park斑岩型矿床早期矿脉中硬石膏的氧同位素组成

本文报道了美国亚利桑那Wallapai矿区Mineral Park斑岩型矿床早期矿脉(AM和AC)中硬石膏的氧同位素组成,依据包体均一温度及硫同位素温度计算成矿溶液的δ~(12)O值(纯水),运用同位素分馏理论讨论AM和AC矿脉成矿溶液的来源和演化。     

Chemical characterization of human urine albumin in proteinuria.

From the urine of a patient with proteinuria, the albumin protein component was isolated and compared with human serum albumin. By comparing the amino acid composition of the original proteins and their large cyanogen bromide fragments, peptide maps and N-terminal sequences of 33 amino acid residues, the identity of both proteins was shown.