Studies on morphogenesis and cellular interactions of Rana grylio virus in an infected fish cell line

A pathogenic virus (RGV), isolated from diseased pig frog Rana grylio with lethal syndrome, was investigated with regard to morphogenesis and cellular interactions in EPC cells, a cell Line from fish. Different stages of virus amplification, maturation and assembly were observed at nucleus, cytoplasm and cellular membranes. The matured virus particles, were not only distributed diffusely in nucleus, cytoplasm and cellular surface, but also aggregated as pseudocrystalline arrays in the cytoplasm. Virions were released by budding from the plasma membranes, or following cell lysis. Various types of cell damage, such as small vacuoles, spherical inclusions, and swollen and empty mitochondria, were also found. Some typical characteristics of RGV, such as the symmetrical shape of the virions, replication process involving both nuclear and cytoplasmic phases, budding release from cellular membrane and intracellular membrane, viromatrix and paracrystalline aggregation in cytoplasm, and its acute pathogenic effects, were observed to be similar to that of other iridoviruses. Therefore, the RGV appears to be a member of the Iridoviridae based on these studies. (C) 1999 Elsevier Science B.V. All rights reserved.

A shortest path algorithm for moving objects in spatial network databases

One of the most important kinds of queries in Spatial Network Databases (SNDB) to support location-based services (LBS) is the shortest path query. Given an object in a network, e.g. a location of a car on a road network, and a set of objects of interests, e.g. hotels,gas station, and car, the shortest path query returns the shortest path from the query object to interested objects. The studies of shortest path query have two kinds of ways, online processing and preprocessing. The studies of preprocessing suppose that the interest objects are static. This paper proposes a shortest path algorithm with a set of index structures to support the situation of moving objects. This algorithm can transform a dynamic problem to a static problem. In this paper we focus on road networks. However, our algorithms do not use any domain specific information, and therefore can be applied to any network. This algorithm’s complexity is O(klog2 i), and traditional Dijkstra’s complexity is O((i + k)2).

若尔盖湿地公路对两栖类的生态影响

本文考察了若尔盖高寒泥炭湿地公路对高原林蛙（Rana kukunoris）、倭蛙（Narorana pleskei）和岷山蟾蜍（Bufo minshanicus）的生态影响。分析了公路对两栖动物空间分布和栖息地利用的影响，并用IBM模型探讨其可能作用机制，考察了两栖动物公路死亡的季节差异及影响公路死亡空间分布的景观因素。最后通过对若尔盖高寒湿地两栖动物陆地核心栖息地的分析，为若尔盖路域栖息地的管理提供依据。 1. 对公路周边6个沼泽水凼群进行了调查，每个样地设置5条样线（距离公路10m、20m、50m、100m和150m）。调查表明，在繁殖季节(5月)，距离公路距离对高原林蛙和倭蛙的相对数量都有显著作用，其效应明显大于其他各项栖息地环境参数。公路导致高原林蛙和倭蛙在公路周边种群密度降低，其相对数量从距离公路100m处到公路边缘一直呈现逐渐降低的趋势。在繁殖季节，若尔盖高寒湿地的公路生态影响域大约在100-150m之间，这一距离远远大于森林栖息地中公路对两栖类的生态影响域（35-40 m）。 在繁殖后期（9月），对公路周边16个草地样点的样线调查表明，公路对周边高原林蛙和倭蛙密度分布并未造成显著影响。 2. 二次模型的拟合表明繁殖季节高原林蛙和倭蛙在公路周边的密度分布符合钟型曲线。前人对森林公路两侧两栖类分布的研究也显示了类似的规律。我们通过基于个体的模型，模拟在了公路边缘100单位距离内的栖息地空间，栖息地环境质量呈梯度变化，动物个体在其中通过随机运动寻找适宜的栖息地。拟合结果表明，动物个体仅仅依照简单的运动规则寻找适宜栖息地，这种活动就可以导致公路周边栖息地中的动物分布曲线出现3个局部峰。公路周边两栖动物的钟型分布曲线可能仅仅是个体寻找适宜栖息地过程中出现的临时性群体分布模式。 3. 在若尔盖高寒湿地，公路交通造成了大量两栖类死亡。但是公路两栖类动物死亡的季节分布很不均匀：5月、8月和9月死亡数量很高，而7月和10月死亡数量却很低。这种季节性差异和两栖类各个生活史阶段的迁移运动有密切的关系。利用景观参数的逻辑斯蒂回归模型显示，距离公路1000-2000m范围内的湿草地比例对三种两栖类公路死亡概率均有很强的贡献。湿草地这一栖息地类型分类中有大量的沼泽水体，是两栖类重要的繁殖点和取食点。两栖类公路死亡概率湿草地的关系从一个侧面表明，要维持一个区域较高的两栖类种群数量，需要1000-2000m半径范围内存在大面积的湿草地。 4. 高原林蛙和岷山蟾蜍不同性别和年龄个体分布点的水体距离存在显著差异。不同种类、年龄的两栖类分布点距离水体距离的差异可能是由于对水体的依赖性造成的。而相同种类、年龄段的个体中，高原林蛙雌性、岷山蟾蜍亚成体和雌性的体重与分布点距水体距离有显著负相关，这可能是因为体重更大的个体对水体的依赖性更弱。考虑到过大的陆地核心栖息地面积在实际保护工作中存在操作上的困难，因此我们认为可以以水体周边90%个体的分布区为低限确定3种两栖类的最小陆地核心栖息地。但是，在同样的水体距离-两栖类密度分布格局下，水体的面积和分形参数对最小陆地核心栖息地半径的确定有一定影响。 Ecological effects of alpine wetland road on Rana kukunoris, Narorana pleskei, Bufo minshanicus was studied in Zoige wetland. The effects of road on distribution of amphibians and its possible underline mechanism was discussed based on empirical data and computer simulation. Road killed amphibians was surveyed in different season and those landscape factor which could have impact on road killing distribution was analyses. Core terrestrial habitat of amphibians in Zoige wetland was discussed in the consideration of conservation management. 1. Six pool groups was investigated in breeding season (May) of R. kukunoris, N. pleskei. Five transects at distance of 10m, 20m, 50m, 100m and 150m from road edge was surveyed in each pool groups. There was a significant effects of distance from road edge on relative counts of R. kukunoris, N. pleskei, which is much important than effects of other environmental factors. Road caused the density of R. kukunoris, N. pleskei decreased from distance of 100m from road to 10m from road. Road ecological effect zone of alpine wetland for amphibians is about 100-150m. It is much wider than those of forest roads, which is about 35-40m. However, studies on 16 grassland near road showed no significant effect of road on amphibians after breeding season (Sep.). 2. Quadratic model fit indicated that the distribution of R. kukunoris and N. Pleskei followed a hump like curve. Previous studies on forest road showed similar results. A 100×100 habitat with gradual environment besides road was simulated with a individual-based model, and animal seek for suitable habitat with stochastic locomotion in it. Simulation results indicated that 3 density peak of animal distribution can emergent followed a simply rules. The hump like density cure could be a temporal swarm pattern during the process of individual seeking for habitat. 3. Road traffic caused mass death of amphibians in Zoige wetland. There was much road killed amphibians in May, Aug and Sep than those in July and Oct. The fluctuation of road kill could be related with migration of amphibians between seasons. Logistic regression of landscape variables indicated that wet grassland in 1000-2000m is essential to predict the probability of road kill. Wet grassland is an important breeding and forage habitat for amphibians. It also indicated that mass wet grassland in 1000-2000m is essential for maintain a big amphibian population. 4. There was significant differences among distance from aquatic site of subadults, female and males of R. kukunoris and B. Minshanicus. Possibly, it was because of their dependence on water. There was a significant negative relationship between distance from aquatic site and individuals body mass. Estimates of core habitat that are too large may make it difficult to establish protective regulations. The smallest suitable terrestrial core habitats were defined as the terrestrial habitats used during migration to and from the wetlands, and for foraging by 90% of any life stage (adults, and subadults) in a season. However, even with the same amphibian distribution pattern along the distance from aquatic sites, the radii of smallest suitable terrestrial core habitats will be varied with the fractal parameters of aquatic site.

Turbulent collision of inertial particles: point-particle based, hybrid simulations and beyond

Point-particle based direct numerical simulation (PPDNS) has been a productive research tool for studying both single-particle and particle-pair statistics of inertial particles suspended in a turbulent carrier flow. Here we focus on its use in addressing particle-pair statistics relevant to the quantification of turbulent collision rate of inertial particles. PPDNS is particularly useful as the interaction of particles with small-scale (dissipative) turbulent motion of the carrier flow is mostly relevant. Furthermore, since the particle size may be much smaller than the Kolmogorov length of the background fluid turbulence, a large number of particles are needed to accumulate meaningful pair statistics. Starting from the relative simple Lagrangian tracking of so-called ghost particles, PPDNS has significantly advanced our theoretical understanding of the kinematic formulation of the turbulent geometric collision kernel by providing essential data on dynamic collision kernel, radial relative velocity, and radial distribution function. A recent extension of PPDNS is a hybrid direct numerical simulation (HDNS) approach in which the effect of local hydrodynamic interactions of particles is considered, allowing quantitative assessment of the enhancement of collision efficiency by fluid turbulence. Limitations and open issues in PPDNS and HDNS are discussed. Finally, on-going studies of turbulent collision of inertial particles using large-eddy simulations and particle- resolved simulations are briefly discussed.

Synthesis and formation mechanism of silver nanowires by a templateless and seedless method

Silver nanowires in large quantities can be obtained through a simple method in the absence of a surfactant or polymer and without addition of external seeding nanocrystallites. A plausible mechanism was proposed to elucidate the formation mechanism of silver nanowires based on TEM studies.

水分胁迫对光合作用影响的研究

1．水分胁迫降低了水稻叶片的光合速率。轻度及中度水分胁迫下，气孔的限制是光合速率下降的主要原因;而严重水分胁迫下，叶肉细胞光合能力的降低是光合速率下降的主要原因。叶肉细胞光 合能力的降低可能是由于光合量子效率、光合电子传递速率和光合磷酸化活力及羧化效率下降所致。 2．水分胁迫降低了小麦叶片的可变荧光产量、可变荧光淬灭速率、荧光上升互补面积，叶绿体的室温荧光产量、可变荧光产量以及DCMU作用下的小麦叶片及叶绿体的可变荧光产量，表明光系统Ⅱ受到了伤害。光系统Ⅱ氧化侧的人工电子供体(DPC) 能部分恢复受抑制的叶绿体可变荧光和光系统II的电子传递速率，说明水分胁迫对光系统Ⅱ的损伤不仅位于氧化侧，也可能在反应中心上。 3．水分胁迫抑制了激发能向PSII的传递;降低了Mg2+对叶绿体可变荧光及激发能在两个光系统间分配的调节能力。水分胁迫使PS II内外周天线色素蛋白复合体（CPa和LHCⅡ）和PSⅠ叶绿素a蛋白复合体(CPⅠ、CPⅠa和CPⅠb)含量下降，其中以LHCⅡ降低幅度最大。从类囊体膜多肽分析结果，发现25KD多肽随着水分胁迫的加剧其含量显著降低。 4．水分供应充分及轻度和中度水分胁迫下，高氮素营养对水稻光合作用有明显的促进作用;而严重水分胁迫则削弱了高氮营养对光合作用的促进作用，使高氮营养水稻叶片在严重水分胁迫下的光合速率反而比低氮营养叶片低，这可能与严重水分胁迫下，高氮叶片水势、气孔导度、光合羧化效率、光合量子产量及RuBP再生速率比低氮叶片有更大的下降有关。两种氮素营养水平下，轻度和中度水分胁迫均提高了叶片的水分利用效率;而严重水分胁迫则使叶片的水分利用效率降低，但始终是高氨营养水稻叶片的水分利用效率高于低氮叶片。

盐胁迫对光合作用的影响

盐害对植物光合作用的影响机理的研究目前还仅仅处于初步阶段，对于许多关键性问题远没有达成共识。本论文研究了盐胁迫对光合作用的影响途径和原初作用部位，对光合作用的各个分过程影响的先后关系，盐胁迫与光胁迫的协同作用，植物光合作用对盐胁迫的适应等基础理论问题，为盐胁迫下提高植物光合作用速率，改良植物种质提供了一定的理论依据。 1．采用荧光动力学的方法区分盐胁迫中的渗透因素和离子因素。用五种等渗Hogland培养液(分别含NaCl，KCl，NaN03，KN03和PEG)对冬小麦进行处理。结果，与对照相比，NaCl处理引起PSII受体侧电子库含量(CA／Fm)、PSII活性(Fv／Fo)、原初光能转化效率(Fv／Fm)、量子产量(Yield)与荧光光化学猝灭系数(qP)下降;QB-非还原性PSII反应中心含量增加。然而，等渗的PEG处理并不产生类似的伤害。这表明渗透因素不是盐胁迫对光合作用造成伤害的主要原因。鉴于NaCl和NaNO3处理却使QA含量、PSII活性、原初光能转化效率下降和QB-非还原性PSII反应中心的增加，KN03处理对光合作用不产生伤害;而等渗的PEG和KCl处理并不产生类似的伤害，这暗示Na+可能是盐胁迫影响光合作用的主要毒害离子。 2．用荧光动力学的方法研究了不同浓度的NaCl处理对PSII光能利用和耗散的影响。结果表明，与对照、100mmol/L和200mmol/L NaCl处理相比，经300mmol/L和400mmol/L NaCl处理的小麦，其荧光光化学猝灭效率明显降低，荧光非光化学猝灭效率较高，Fo猝灭系数较大，QB-非还原性PSII反应中心含量较大，然而，其荧光非光化学猝灭效率，QB-非还原性PSII反应中心含量和Fo猝灭系数潜在增高能力较弱。随着NaCl处理浓度的增加，PSII吸收过多的光能可能首先通过热耗散和状态转换逸散，而后阻断PSII从QA到QB的电子传递，最后损伤PSII反应中心。 3．研究了轻度(200mmol/L)和重度(400mmol/L)NaCl胁迫对光抑制和光恢复进程的影响。结果表明：1)轻度盐胁迫对光合放氧和碳同化速率的影响相对较小，而重度盐胁迫大大降低了光合放氧和碳同化速率，同时明显降低光合放氧和碳同化的光饱和点。2)碳同化是盐胁迫对光合作用造成伤害的敏感位点。3)轻度盐胁迫对PSII的光抑制进程影响较小;而重度盐胁迫则促进光抑制的产生，同时抑制PSII的修复过程，从而使得PSII受到光抑制的伤害更大。 4 为探讨盐胁迫下植物减轻或避免光抑制的机制，研究了盐胁迫对光能在PSI和PSII之间的分配的影响。结果表明，盐胁迫提高了Chla/Chlb比值和单位鲜重叶片中Chla的含量，降低了单位鲜重叶片Chlb的含量;提高了PSI的电子传递速度，能量储存;同时降低了PSII的电子传递和能量储存。这表明盐胁迫提高了光能在PSI的分配分额和PSI的含量，降低PSII对光能的吸收和利用，这对于植物在盐胁迫下减轻或避免光抑制对PSII的破坏有重要意义。

Distribution and bioaccumulation of microcystins in water columns: A systematic investigation into the environmental fate and the risks associated with microcystins in Meiliang Bay, Lake Taihu

For the purpose of understanding the environmental fate of microcystins (MCs) and the potential health risks caused by toxic cyanobacterial blooms in Lake Taihu, a systematic investigation was carried out from February 2005 to January 2006. The distribution of MCs in the water column, and toxin bioaccumulations in aquatic organisms were surveyed. The results suggested that Lake Taihu is heavily polluted during summer months by toxic cyanobacterial blooms (with a maximum biovolume of 6.7 x 10(8) cells/L) and MCs. The maximum concentration of cell-bound toxins was 1.81 mg/g (DW) and the dissolved MCs reached a maximum level of 6.69 mu g/L. Dissolved MCs were always found in the entire water column at all sampling sites throughout the year. Our results emphasized the need for tracking MCs not only in the entire water column but also at the interface between water and sediment. Seasonal changes of MC concentrations in four species of hydrophytes (Eichhornic crassipes, Potamogeton maackianus, Alternanthera philoxeroides and Myriophyllum spicatum) ranged from 129 to 1317, 147 to 1534, 169 to 3945 and 124 to 956 ng/g (DW), respectively. Toxin accumulations in four aquatic species (Carassius auratus auratu, Macrobrachium nipponensis, Bellamya aeruginosa and Cristaria plicata) were also analyzed. Maximum toxin concentrations in the edible organs and non-edible visceral organs ranged from 378 to 730 and 754 to 3629 ng/g (DW), respectively. Based on field studies in Lake Taihu, risk assessments were carried out, taking into account the WHO guidelines and the tolerable daily intake (TDI) for MCs. Our findings suggest that the third largest lake in China poses serious health threats when serving as a source of drinking water and for recreational use. In addition, it is likely to be unsafe to consume aquatic species harvested in Lake Taihu due to the high-concentrations of accumulated MCs. (C) 2007 Elsevier Ltd. All rights reserved.

A surface kinetics model for the growth of Si1-xGex by UHV/CVD using SiH4/CeH4

The surface reaction mechanism of Si1-xGex/Si growth using SiH4 and GeH4 in UHV/CVD system was studied. The saturated adsorption and desorption of SiH4 from Si(1 0 0) surface was investigated with the help of TPD and RHEED, and it was found that all the 4 hydrogen atoms of one SiH4 molecule were adsorbed to the Si surface, which meant that the dissociated adsorption ratio was proportional to 4 power of surface vacancies. The analysis of the reaction of GeH4 was also done. A new surface reaction kinetic model on Si1-xGex/Si epitaxial growth under UHV conditions by SiH4/GeH4 was proposed based on these studies. The predictions of the model were verified by the experimental results. (C) 2000 Elsevier Science B.V. All rights reserved.

基于路网的不确定性轨迹预测

移动对象的轨迹预测研究已成为当前移动对象研究中关注的热点,移动对象的轨迹预测技术具有高度的研究价值及广阔的应用前景.目前移动对象的轨迹预测方法主要是针对历史轨迹确定的欧氏空间轨迹预测,但有相当一部分的应用要求预测历史轨迹存在不确定性的移动对象在受限路网中的轨迹.为了解决这一问题,首先提出了不确定性轨迹的生成方法及其表示形式,然后提出了一种基于路网的不确定性轨迹频繁模式挖掘算法,最后给出了利用索引快速查找轨迹模式并进行预测的方法.实验结果表明该方法具有较高的预测准确率、较好的查询效率以及较低的存储空间.

中国水土流失的成因、威胁及其防治途径

本文在对以往研究结果进行综合分析的基础上 ,提出了我国水土流失的成因、危害及防治途径。

黄土高原典型地区土壤侵蚀共性与特点

通过对黄土高原典型地区土壤侵蚀以往的研究结论进行综合分析 ,在比较土壤侵蚀相似性和差异性的基础上 ,对这些典型地区土壤侵蚀的共性与特点进行了研究 ,结果表明 :1、黄土高原典型地区土壤侵蚀影响因素有降雨、地形及土地利用 ;2、黄土高原各典型地区主要侵蚀类型为水蚀及重力侵蚀 ;主要侵蚀发生时间为汛期 ;主要侵蚀空间分布特征为具有垂直分带性 ;3、绥德地区侵蚀产沙强烈 ,天水地区侵蚀相对轻微 ,安塞地区各种侵蚀特征典型 ,西峰地区土壤侵蚀特殊。

Solvent-dependent formation of di- and trinuclear rhodiurn and iridium complexes bridged by N,N '-donor ligands

Reactions of Rh and Ir hydrido complexes. [Rh(H)(2)(PPh3)(2)(solv)(EtOH)]ClO4 (solv = Me2CO, 1a; EtOH, 1b) and [Ir(H)(2)(PPh3)(2)(Me2CO)(2)]BF4 (2), with various N,N'-donor bridging ligands, such as pyrazine (pyz), 4,4'-trimethylenedipyridine (tmdp) and di(4-pyridyl) disulfide (dpds), in some solvents were examined, and their reaction products were characterized by X-ray crystal structure analysis. IR, H-1 NMR and UV-vis spectra. Rh hydrido complexes, la or 1b, formed a dinuclear Rh complex, [Rh-2(PPh3)(2) {(eta(6)-C6H5PPh2}(2)] (ClO4)(2).6CH(2)Cl(2) (3.6CH(2)Cl(2)), in dichloromethane with a reductive elimination of hydrogen. The reactions of 1a or 1b with the pyz ligand in dichloromethane and tetrahydrofuran gave triangular Rh-3 complexes, [Rh-3(PPh3)(6)(pyz)(3)](ClO4)(3).CH2Cl2 (5.CH2Cl2) and [Rh-3(PPh3)(6)(pyz)(3)](ClO4)(3).EtOH (5.EtOH), respectively, in contrast to the formation of a dinuclear Rh hydrido complex, [Rh-2(H)(4)(PPh3)(4)(Me2CO)(2)(pyz)](ClO4)(2).EtOH A-EtOH). in acetone. The reactions of la or 1b with the tmdp ligand in dichloromethane and 3-methyl-2-butanone also afforded dinuclear Rh complexes, [Rh-2(PPh3)(4)(tmdp)(2)](ClO4)(2) (6) and [Rh-2(PPh3)(4)(tmdp)(2)](ClO4)(2).4MeCOCHMe(2) (6.4MeCOCHMe(2)), respectively. On the other hand, Ir hydrido complex 2 reacted with pyz and dpds ligands in dichloromethane to afford dinuclear Ir complexes, [Ir-2(H)(4)(PPh3)(4)(Me2CO)(2)(pyz)]- (BF4)(2).3CH(2)Cl(2) (7.3CH(2)Cl(2)) and [Ir-2(H)(4)(PPh3)(4)(dpds)(2)](BF4)(2).3CH(2)Cl(2).H2O (8.3CH(2)Cl(2).H2O), respectively, without any reductive elimination of hydrogen. Based on structural studies in solution and in the solid state. it was demonstrated that various Rh and Ir complexes were selectively produced depending on the choice of solvents and N,N'-donor bridging ligands.

基于DSRC的多功能不停车收费系统

DSRC标准是ISO/TC204制定的智能交通系统(ITS)中车—路信息通讯的协议。采用双片式ETC电子标签结合双界面IC卡的储值卡方案形成的多功能不停车收费系统,充分兼容了当前国内普遍应用的IC卡半自动收费方式,集中了IC卡收费系统和ETC收费系统的优点,方便、快捷、通行能力强,并解决了收费口的交通拥挤现象。