Investigation Of Mode Ii Crack Growth Following A Very High Speed Impact

A recoverable plate impact testing technology has been developed for studying fracture mechanisms of mode II crack. With this technology, a single duration stress pulse with submicrosecond duration and high loading rates, up to 10(8) MPam(1/2)s(-1), can be produced. Dynamic failure tests of Hard-C 60# steel were carried out under asymmetrical impacting conditions with short stress-pulse loading. Experimental results show that the nucleation and growth of several microcracks ahead of the crack tip, and the interactions between them, induce unsteady crack growth. Failure mode transitions during crack growth, both from mode I crack to mode II and from brittle to ductile fracture, were observed. Based on experimental observations, a discontinuous crack growth model was established. Analysis of the crack growth mechanisms using our model shows that the shear crack extension is unsteady when the extending speed is between the Rayleigh wave speed c(R) and the shear wave speed c(S). However, when the crack advancing speed is beyond c(S), the crack grows at a steady intersonic speed approaching root 2c(S). It also shows that the transient mechanisms, such as nucleation, growth, interaction and coalescence among microcracks, make the main crack speed jump from subsonic to intersonic and the steady growth of all the subcracks causes the main crack to grow at a stable intersonic speed.

减压直流非转移弧等离子体射流速度的静电探针测量

组建了一套利用静电探针诊断技术测量减压直流非转移弧等离子体射流速度的实验系统.对以纯氩为工质的等离子体,在气流量1.25×10~(-4) kg/s、弧电流80A、真空室压力165 Pa的条件下,测量了射流的速度及其分布.结果表明射流在发生器出口处中心最高速度约为1 200 m/s,在半径20 mm处减小到635 m/s.沿射流轴线方向的速度梯度约为10 (ms~(-1))/mm.射流速度随着弧电流增加而缓慢单调增加;当真空室压力从165 Pa提高到2 kPa时,发生器出口轴线上的射流速度从1200 m/s降至570 m/s.

九万山藓类植物的区系研究

九万山位于广西省的北部，横贯融水、环江和罗城等县，东经108°27'-59'，北纬25°10'-25°25'地处我国两大植物区系（泛北极植物区和古热带植物区）的交汇区域，属于亚热带常绿阔叶林地区。最高海拔1693m，最低处仅170m。 经对所获得的约1500号藓类植物标本的鉴定，得知本地区的藓类植物共有35科，101属，189种。其区系成分以东亚成分为主（39.33%），其次为热带，亚热带成分（38.20%），温带成分仅占18.54%。 选取九万山周围5个地区与其比较，在属和种的相似性方面与福建西北部的武夷山具较密切的关系。 东亚成分的种类中，中国-日本成分的数目明显高于中国—喜马拉雅成分，并有四个东亚特有的藓类植物属。它们的分布范围更具偏南的特点。 九万山的典型热带分布的属和种系组成它区系的重要因素之一，一般来说，这些属的分布范遍及新旧热带地区，而其热带种类则相应贫乏，它们多局限在热带亚洲，通过定量和定性讨论，作者认为：从苔藓植物角度分析九万山呈现由热带向亚热带过渡的特性，其分界线可能位于它的南侧。

Developmental potential of vitrified holstein cattle embryos fertilized in vitro with sex-sorted sperm

In vitro fertilization (IVF) is a feasible way to utilize sex-sorted sperm to produce offspring of a predetermined sex in the livestock industry. The objective of the present study was to examine the effects of various factors on bovine IVF and to systema

广西高原鳅属鱼类一穴居新种记述

2003 年1 月, 在广西壮族自治区天峨县红水河水系地下河采集到一批盲鱼标本。经鉴定, 为高原鳅 属Triplophysa 一未经发表的新种。新种天峨高原鳅Triplophysa tianeensis sp1nov1 与个旧盲高原鳅T. gejiuensis 、 石林盲高原鳅T. shilinensis 、阿庐高原鳅T. aluensis 和南丹高原鳅T. nandanensis 相似; 本新种腹鳍末端不达 肛门, 尾鳍分枝鳍条16 , 可进一步与个旧盲高原鳅和石林盲高原鳅(腹鳍末端达到肛门, 尾鳍分枝鳍条14～ 15) 相区别; 本新种背鳍起点位于体之中点、腹鳍起点之后, 肛门紧靠臀鳍起点, 可进一步与阿庐高原鳅(背 鳍起点靠近吻端、位于腹鳍起点之前, 肛门距臀鳍起点仍有一段距离) 相区别。本新种与同分布于红水河水系 的南丹高原鳅Triplophysa nandanensis Lan et al1 较为相似; 但二者区别明显: 新种背鳍分枝鳍条7 、胸鳍分枝鳍 条9 、腹鳍分枝鳍条6 、背鳍外缘平截、背鳍起点位于腹鳍起点之后, 后者背鳍分枝鳍条8 、胸鳍分枝鳍条10～ 11 、腹鳍分枝鳍条7 、背鳍外缘凹入、背鳍起点位于腹鳍起点之前; 此外, 新种的穴居特征更为显著: 眼极度 退化、头长为眼径1618～3218 (2510) 倍、部分个体无色素斑且各鳍无斑点, 而南丹高原鳅眼小、头长为眼径 417～910 (715) 倍、体和头背侧密布云状斑且各鳍均具点状斑。

给黄鳝服用了激素类药物吗?

本文从“激素黄鳝”传言的由来、避孕药的本质、催肥机制、给药途径、外源激素在黄鳝养殖和研究中的应用、黄鳝养殖生产现状等方面进行了分析,认为“激素黄鳝”的说法是不正确的,在养殖生产中黄鳝服用激素类药物增肥既没有可能,也没有必要,在经济上也不合算。

Uniform AMoO(4):Ln (A = Sr2+, Ba2+; Ln = Eu3+, Tb3+) submicron particles: Solvothermal synthesis and luminescent properties

Rare-earth ions (Eu3+, Tb3+) doped AMoO(4) (A = Sr, Ba) particles with uniform morphologies were successfully prepared through a facile solvothermal process using ethylene glycol (EG) as protecting agent. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) spectra and the kinetic decays were performed to characterize these samples. The XRD results reveal that all the doped samples are of high purity and crystallinity and assigned to the tetragonal scheelite-type structure of the AMoO(4) phase. It has been shown that the as-synthesized SrMoO4:Ln and BaMoO4:Ln samples show respective uniform pea nut-like and oval morphologies with narrowsize distribution. The possible growth process of the AMoO(4):Ln has been investigated in detail. The EG/H2O volume ratio, reaction temperature and time have obvious effect on themorphologies and sizes of the as-synthesized products.

一种脱除高浓度二氧化氮的方法及其设备

一种脱除高浓度二氧化氮的方法及其设备，以甲醇裂解生成的氢气和一氧化碳为燃料，点燃该燃料之后，通入１０－１００％体积百分比浓度的二氧化氮气体一同燃烧，生成水和二氧化碳和氮气，达到处理氮氧化物的目的。具有工艺简单操作容易，设备简单，燃烧尾气中的二氧化氮残余量小于４００ＰＰｍ，总氮氧化物残余量小于６００ＰＰｍ。

一种含酞侧基聚醚醚酮的稀溶液性质的研究(Ⅰ)

本文用光散身的粘度法研究了一种含酞侧基的聚醚醚酮(PEK-C)在氯仿(CKCl_3)和二甲基酰胺(DMF)中的稀溶液性质,建立了PEK-C在两种溶剂中的Mark-Houwink方程:并得到了高分子一溶剂相互作用参数χ_1和PEK-C的特征常数K_θ值: K_θ=6.25×10~(-2)ml/g,X_1=0.48,CHCl_3 K_θ=4.42×10~(-2)ml/g,X_1=0.49,DMF以及流体力学扩张因子α_η~3与分子量间的函数关系。

Identification and expression of TRAF6 (TNF receptor-associated factor 6) gene in Zhikong Scallop Chlamys farreri

Tumor necrosis factor receptor-associated factor 6 (TRAF6), a key signaling adaptor molecule common to the TNFR superfamily and IL-IR/TLR family, is important not only for a diverse array of physiological processes functions of the TNFR superfamily, but also is involved in adaptive immunity and innate immunity. In this report, the first bivalve TRAF6 (named as CfTRAF6) gene is identified and characterized from Zhikong scallop Chlamys farreri. The full-length cDNA of CfTRAF6 is of 2510 bp, consisting of a 5'-terminal untranslated region (UTR) of 337 bp, a 3'-terminal UTR of 208 bp with a canonical polyadenylation signal sequence AATAAA and a poly (A) tail, and an open reading frame (ORF) encoding a polypeptide of 655 amino acids. The predicted amino acid sequence of CfTRAF6 comprises characteristic motifs of the TRAF proteins, including a Zinc finger of RING-type, two Zinc fingers of TRAF-type, a coiled-coil region, and a MATH (the meprin and TRAF homology) domain. The overall amino acid sequence identity between CfTRAF6 and other TRAF6s is 28-68%. Phylogenetic analyses of CfTRAF6 sequence with TRAF sequences from other organisms indicate that CfTRAF6 is a true TRAF6 orthologue. The mRNA expression of CfTRAF6 in various tissues is measured by Real-time RT-PCR. The mRNA transcripts are constitutively expressed in tissues of haemocyte, muscle, mantle, heart, gonad and gill, but the highest expression is observed in the gonad. The temporal expressions of CfTRAF6 mRNA in the mixed primary cultured haemocytes are recorded after treatment with 20 mu g mL(-1) and 0.5 mu g mL(-1) peptido-glycan (PGN). The expression level of CfTRAF mRNA is down-regulated from 1.5 h to 3 h after the treatment with 0.5 mu g mL(-1) PGN, and then recovers to the original level. While the expression of CfTRAF6 is obviously decreased after treatment with 20 mu g mL(-1) PGN, and reach the lowest point (only about 1/9 times to control) at 3 h. The result Suggests that CfTRAF6 can be greatly regulated by PGN and it may be involved in signal transduction and immune response of scallop. (C) 2008 Published by Elsevier Ltd.

东黄海海洋蓝细菌（Svnechococcus）生态学研究

该文对中国黄海和东海的蓝细菌在春、秋两季的生态分布特点进行了研究和比较,对黄海蓝细胞从10月至次年6月的生态分布进行了研究.1.东黄海海区：在秋季（2000年10月19日至11月29日）和春季（2001年3月26日至4月24日）两个季节中蓝细菌丰度在0.19～7.84×10<'4>cell/ml之间,生物量在0.56～13.74μgC/L之间,整体水平上春季比秋季高（蓝细菌的丰充与生物量平均值春季分析为4.83×10<'4>cell/ml和7.25μgC/L;秋季分别为1.72×10<'4>cell/ml和5.07μgC/L）,东海比黄海高（蓝细菌生物量平均值春季黄海和东海分别为4.42μgC/L和5.52μgC/L;秋季黄海和东海分别为7.02μgC/L和7.45μgC/L）.2.黄海海区：黄海蓝细菌丰度与生物量随时间变化趋势为10月至12月降低（蓝细菌丰度分别为15×10<'4>cell/ml和1.19×10<'4>cell/ml,生物量分别为4.41μgC/L和3.49×10<'4>cell/ml）,4月（蓝细菌丰度与生物量分别为4.68×10<'4>cell/ml和7.02μgC/L）与12月相比有明显增高,蓝细菌丰度4月是12月的3.93倍,生物量4月是12月的2.01倍,4月至6月蓝细菌生物量大致稳定,略有增加（5月和6月蓝细菌丰度分别为5.23×10<'4>cell/ml和5.25×10<'4>cell/ml,生物量分别为7.85μgC/L和7.88μgC/L）.研究发现蓝细菌在水体中的垂直分布与温度变化比较一致.

贵州赫章土法炼锌导致的重金属积累

贵州省赫章县的土法炼锌不仅导致植被的破坏，而且使附近土壤和溪流沉积物中重金属有不同程度的积累，土壤中w(Pb)达到37．24×lO^-6～30100×lO^-6，w(Zn)为162．23×lO^-6～31625×lO^6。，w(Cd)为O．50×lO^-6～113×lO^-6，大大超过了当地的土壤背景值；沉积物中w(Pb)达到325．00×lO^-6～21850×lO^-6，w(Zn)为1250．00×10^-6～30425×10^-6，w(Cd)为25×10^-6～97×10^-6。土壤和沉积物中Pb、Zn含量与Al2O3有极显著的正相关性；土壤中重金属Pb、压含量与A12O3有极显著的正相关性，而沉积物中Pb、压含量与Al2O3则没有相关性。土壤和沉积物中铁矿物(铁氧化物和氢氧化物)对重金属的强烈固定作用。连续提取法对化学形态研究表明，Pb、办在土壤中主要表现为铁锰氧化物结合态与残渣态，而在沉积物中则主要为碳酸盐结合态、残渣态和铁锰氧化物结合态。土壤中可交换态Pb、压所占的比例很小，但其绝对含量变化较大，w(Pb)从最低2．75×lO^-6到最高310．4l×l0^-6，w(Zn)4．94×lO^-6～321．10×lO^-6。沉积物中w(Pb)7．42×lO^-6～98．9l×lO^-6;w(zn))9．97×lO^-6～72．67×lO^-6。土壤中重金属Pb、压的有效性程度明显高于溪流沉积物，对生态环境的潜在危害更大.