Scanning electron microscopy of Aspidogaster ijimai Kawamura, 1913 and A-conchicola Baer, 1827 (Aspidogastrea, Aspidogastridae) with reference to their fish definitive-host specificity

Two species of aspidogastreans, namely Aspidogaster ijimai and A. conchicola, were studied by scanning electron microscopy. In nine lakes and an old river course, the Tian'ezhou oxbow, investigated in the flood plain of the Yangtze River, A. ijimai was obtained from the common carp (Cyprinus carpio) in three lakes, and A. conchicola from the black carp Mylopharyngodon piceus in three lakes and the oxbow. In none of the localities, however, were the two species found together. It is suggested that A. ijimai may be considered as a specialist parasite for the common carp, at least in the flood-plain lakes of the Yangtze River. The two parasites were similar in many aspects of their morphology. Their bodies can both be separated into a dorsal part and a ventral disc, with the body surface of the dorsal part elevated by transverse folds, and the disc subdivided into alveoli by transverse and longitudinal septa, although the number of alveoli was different in the two species. The depression on the ventral surface of the neck region was prominent for both species, and their ventral disc was covered densely with non-ciliated bulbous papillae. The position of mouth, osmo-regulatory pore and marginal organ was also similar for A. ijimai and A. conchicola. However, microridges in the trough of the folds in the neck region and numerous small pits on the upper part of the septa were found exclusively in A. ijimai, but uniciliated sensory papillae in A. conchicola.

Behaviour of Gaseous Chlorine and Alkali Metals During Biomass Thermal Utilisation

The behaviour of gaseous chlorine and alkali metals of three sorts of biomass (Danish straw, Swedish wood, and sewage sludge) in combustion or gasification is investigated by the chemical equilibrium calculating tool. The ranges of temperature, air-to-fuel ratio, and pressure are varied widely in the calculations (T=400-1800 K, gimel=0-1.8, and P=0.1-2.0 MPa). Results show that the air excess coefficient only has less significant influence on the release of gaseous chlorine and potassium or sodium during combustion. However, in biomass gasification, the influence of the air excess coefficient is very significant. Increasing air excess coefficient enhances the release of HCl(g), KOH(g), or NaOH(g) as well as it reduces the formation of KCl(g), NaCl(g), K(g), or Na(g). In biomass combustion or straw and sludge gasification, increasing pressure enhances the release of HCl(g) and reduces the amount of KCI(g), NaCl(g), KCI(g), or NaOH(g) at high temperatures. However, during wood gasification, the pressure enhances the formation of KOH(g) and KCI(g) and reduces the release of K(g) and HCl(g) at high temperatures. During wood and sewage sludge pyrolysis, nitrogen addition enhances the formation of KCN(g) and NaCN(g) and reduces the release of K(g) and Na(g). Kaolin addition in straw combustion may enhance the formation of potassium aluminosilicate in ash and significantly reduces the release of KCl(g) and KOH(g) and increases the formation of HCl(g).

水平荷载作用下张力腿平台吸力式基础的物理模拟

介绍了张力腿平台吸力式基础在水平静载和循环动荷载作用下的离心模型试验。通过水平静载离心试验获得了基础的水平承载力。利用电磁式激振器模拟动荷载，研究在动荷载作用下吸力式基础的动力响应，并比较了荷载强度和基础刚度对基础动力响应的影响。分析结果表明，在动荷载作用下，泥面下1～2m深度内土体中孔压最大。当动荷载强度超过临界承载力时，基础周围土体有非常强的液化可能性。综合孔压变化和基础沉降规律分析基础有两种可能的破坏模式：振动最初1～2h内的液化破坏和长时间激振后沉降过大引发的问题。将单桶连接成多桶基础，增大基础刚度，在相同动载强度下，周围孔压增长和激振沉降均小于承受相同荷载条件的单桶基础。

粉质粘土中的刚性桩在横向载荷作用下失稳的模型试验研究

为解释横向载荷作用下刚性桩的失稳机理,针对桩头自由的刚性桩做了一系列横向加载试验.基础土为粉质粘土,含水量介于9.85%～13.85%之间.由载荷-位移全过程曲线发现,刚性桩在横向载荷达到一定值时会失稳;由试验录像及土体剖面发现,由于土体的软化破坏,在桩后土体内会出现贯穿的局部破坏并形成一楔体,同时在土面伴随一不完全的椭圆形鼓包及一条平行于加载方向的拉伸裂缝,而在桩前土中,由于桩的挤压会形成一条侵彻沟.分析认为,对大位移刚性桩桩后土体的破坏是桩失稳的根本原因.

Improvement of sensitivity and refractive-index changes in LiNbO3 : Ce : Cu crystals with UV light

A nonvolatile recording scheme is proposed using LiNbO3:Ce:Cu crystals and modulated UV light to record gratings simultaneously in two centres and using red light to bleach the grating in the shallow centre to realize persistent photorefractive holographic storage. Compared with the normal UV-sensitized nonvolatile holographic system, the amplitude of refractive-index changes is greatly increased and the recording sensitivity is significantly enhanced by recording with UV light in the LiNbO3:Ce:Cu crystals. Based on jointly solving the two-centre material equations and the coupled-wave equations, temporal evolutions of the photorefractive grating and the diffraction effciency are effectively described and numerically analysed. Roles of doping levels and recording-beam intensity are discussed in detail. Theoretical results confirm and predict experimental results.

板条激光放大器中寄生振荡的研究

寄生振荡的存在使得放大器在信号光到达之前消耗了大量的反转粒子数,降低了放大器的激光增益和储能效率,严重地影响了激光放大器的性能,尤其对高功率激光放大器。在理论分析和实验研究的基础上,以Nd∶YAG晶体板条为例,用8条半导体激光阵列对晶体进行双侧抽运,研究了高功率激光放大器的寄生振荡现象,分析了板条晶体寄生振荡产生的原因,并详细比较了晶体在不同的抽运功率和表面处理下的放大效果,得到了2倍的单程放大,当输入能量为140 mJ时,获得了278 mJ的激光输出。

睡莲科的花的生物学和生殖形态学研究

最近的一系列分子系统发育分析一致认定睡莲目为3 个最早的被子植物谱系（ 即包括Amborellaceae 、睡莲目和一个由八角目、Trimeniaceae 、 Austrobaileyaceae 组成的分支在内的ANITA）之一，这些研究结果和新近发现的早白垩世时期的睡莲类植物花化石的记录，支持过去长期认为睡莲目代表原始类群的观点。作为睡莲目组成之一的睡莲科，虽然在被子植物分类系统中一直处于关键的核心的系统发育位置，但对于这个科的生殖生物学和生殖形态学的研究还没有得到足够的重视。本文对睡莲科的王莲属、萍蓬草属和睡莲属的花的生物学、 Nuphar microphylla 的胚胎学、睡莲科的花粉形态学、睡莲科的胚珠和种子的发育形态学、以及睡莲科的柱头的形态解剖学开展了深入细致的研究工作。 本文所研究的睡莲科植物的花都具有开花生物钟的特性，在开花时期花器官的开放和闭合呈现有规律的运动。睡莲科的有些种植物（如睡莲属的一些种）的花是白天开放晚上闭合，而另外一些种（如王莲属）的花却是晚上开放白天闭合。睡莲科的不同物种的花的开花天数不同，一般是2 到数天。花大多是雌性先熟的，通常从开花的第二天开始释放花粉。睡莲科的不同属植物在开花时间，花的气味，花的颜色，各种花器官的形状和功能，以及传粉者方面存在很大差异。克鲁兹王莲的花具有大型的，单生的，多数花器官，花器官呈现有规律的开放和闭合运动，雌性先熟，能散发强烈气味，能够改变颜色，温度发生变化等特征。作者认为这些特征是高度特化的，它们适应于昆虫传粉。对Nuphar microphylla 的花的生物学研究支持Lippok 等人的观点：在任何居群，蝇、蜜蜂和甲虫对传粉贡献的相对大小更多地取决于这些昆虫的相对丰富度和可替换食物的多少，而不是取决于旧世界与新世界的萍蓬草属植物之间的雄蕊长度的差异。 本研究首次在Nuphar microphylla 中发现了一种新的4 细胞5 核雌配子体（具有1 个卵细胞，2 个助细胞和1 个具有2 个单倍体核的中央细胞）类型，这种雌配子体通过受精作用将产生三倍体的胚乳。作者认为这种雌配子体可能是最小的性功能单位，代表着被子植物的祖征。 睡莲科是一个具有多形态花粉的科，花粉沟有远极单槽和环槽两种类型。当前研究建议萍蓬草属的远极单槽花粉在睡莲科中是最原始类型。花粉形态学研究支持睡莲科是一个原始类群的观点。在所观察的睡莲科植物中，内珠被都作为一圈圆形的突起被产生，而外珠被是半圆形的，稍后形成兜状，在珠柄的凹面侧没有外珠被。在印度红睡莲、埃及白睡莲、墨西哥黄睡莲、芡实、以及克鲁兹王莲的胚珠的发育后期，珠柄的凹面侧产生不同长度的外珠被，所以它们成熟胚珠的外珠被为杯状。作者认为睡莲科的兜状的外珠被是原始的，杯状的外珠被是进化的。睡莲科的柱头形态高度多样化。睡莲属的柱头表面分布有许多拥挤的多细胞的乳头，萍蓬草属和芡实属的柱头是分泌性的，柱头表面具有单细胞乳突。王莲属柱头表面形成许多不规则的隆起。柱头形态学研究支持睡莲属和Ondinea 具有密切的亲缘关系的观点。

抗艾滋病的药物组合物及其应用

一种抗艾滋病的药物组合物，其中含有抗艾滋病有效量的式（Ⅰ） 化合物β－硝基苯乙烯及可药用载体和／或赋形剂。$上述药物组合物在制备逆转录酶抑制剂药物中的应用；上述药物组合物在制备抗艾滋病药物中的应用.

Natural selection on EPAS1 (HIF2 alpha) associated with low hemoglobin concentration in Tibetan highlanders

By impairing both function and survival, the severe reduction in oxygen availability associated with high-altitude environments is likely to act as an agent of natural selection. We used genomic and candidate gene approaches to search for evidence of such genetic selection. First, a genome-wide allelic differentiation scan (GWADS) comparing indigenous highlanders of the Tibetan Plateau (3,200 3,500 m) with closely related lowland Han revealed a genome-wide significant divergence across eight SNPs located near EPAS1. This gene encodes the transcription factor HIF2 alpha, which stimulates production of red blood cells and thus increases the concentration of hemoglobin in blood. Second, in a separate cohort of Tibetans residing at 4,200 m, we identified 31 EPAS1 SNPs in high linkage disequilibrium that correlated significantly with hemoglobin concentration. The sex-adjusted hemoglobin concentration was, on average, 0.8 g/dL lower in the major allele homozygotes compared with the heterozygotes. These findings were replicated in a third cohort of Tibetans residing at 4,300 m. The alleles associating with lower hemoglobin concentrations were correlated with the signal from the GWADS study and were observed at greatly elevated frequencies in the Tibetan cohorts compared with the Han. High hemoglobin concentrations are a cardinal feature of chronic mountain sickness offering one plausible mechanism for selection. Alternatively, as EPAS1 is pleiotropic in its effects, selection may have operated on some other aspect of the phenotype. Whichever of these explanations is correct, the evidence for genetic selection at the EPAS1 locus from the GWADS study is supported by the replicated studies associating function with the allelic variants.

Effects of unconditioned and conditioned aversive stimuli in an intense fear conditioning paradigm on synaptic plasticity in the hippocampal CA1 area in vivo

Repeated vivid recalls or flashbacks of traumatic memories and memory deficits are the cardinal features of post-traumatic stress disorder (PTSD). The underlying mechanisms are not fully understood yet. Here, we examined the effects of very strong fear conditioning (20 pairings of a light with a 1.5-mA, 0.5-s foot shock) and subsequent reexposure to the conditioning context (chamber A), a similar context (chamber B), and/or to the fear conditioned stimulus (CS) (a light) on synaptic plasticity in the hippocampal CA1 area in anesthetized Sprague-Dawley rats. The conditioning procedure resulted in very strong conditioned fear, as reflected by high levels of persistent freezing, to both the contexts and to the CS, 24 h after fear conditioning. The induction of long-term potentiation ON was blocked immediately after fear conditioning. It was still markedly impaired 24 h after fear conditioning; reexposure to the conditioning chamber A (CA) or to a similar chamber 13 (CB) did not affect the impairment. However, presentation of the CS in the CA exacerbated the impairment of LTP, whereas the CS presentation in a CB ameliorated the impairment so that LTP induction did not differ from that of control groups. The induction of long-term depression (LTD) was facilitated immediately, but not 24 h, after fear conditioning. Only reexposure to the CS in the CA, but not reexposure to either chamber A or B alone, or the CS in chamber B, 24 h after conditioning, reinstated the facilitation of LTD induction. These data demonstrate that unconditioned and conditioned aversive stimuli in an intense fear conditioning paradigm can have profound effects on hippocampal synaptic plasticity, which may aid to understand the mechanisms underlying impairments of hippocampus-dependent memory by stress or in PTSD. (c) 2005 Wiley-Liss, Inc.

黑腹果蝇黑条体突变体突变位点的鉴定

根据果蝇ebony基因的序列设计了一系列特异性引物,对1991年发现的一种黑腹果蝇的新的体色突 变(Qian&Zhang,1994)——黑条体突变型的ebony基因进行克隆和序列测定。与野生型W91910的ebony基因 相比,黑条体突变型的ebony基因的编码区无明显的大片段变异,变异仅存在于数个氨基酸位点,且均不位于 该基因产物的关键序列。在黑条体的ebony基因的5’端序列的克隆和序列测定中发现,与野生型W91910及黑檀体 e’的ebony基因相比,黑条体突变型的ebony基因有一个大片段的缺失,