The involvement of the antioxidant system in protection of desert cyanobacterium Nostoc sp against UV-B radiation and the effects of exogenous antioxidants

In this study, we found that UV-B radiation decreased photosynthetic activity and boosted lipid peroxidation of desert Nostoc sp., and exogenous chemicals (ascorbate acid (ASC), N-acetylcysteine (NAC), and sodium nitroprusside (SNP)) had obvious protective effects on photosynthesis and membranes under UV-B radiation. High-concentration SNP boosted the activities of antioxidant enzymes, but low-concentration SNP reduced the activities of antioxidant enzymes. Both NAC and ASC treatments of cells decreased activities of antioxidant enzymes. The results suggested that those chemicals possibly had different mechanisms of protection of algae cells against UV-B radiation. SNP might play double roles as a signal molecule in the formation of algae cell protection of Photosystem 11 under UV-B radiation and as a (reactive oxygen species) scavenger, while NAC and ASC might function as antioxidant reagents or precursors of other antioxidant molecules, which could protect cells directly against ROS initiated by UV-B radiation. (c) 2006 Elsevier Inc. All rights reserved.

Subcellular localization and characterization of G protein-coupled receptor homolog from lymphocystis disease virus isolated in China

G protein-coupled receptors (GPCRs) constitute a large superfamily involved in various types of signal transduction pathways, and play an important role in coordinating the activation and migration of leukocytes to sites of infection and inflammation. Viral GPCRs, on the other hand, can help the virus to escape from host immune surveillance and contribute to viral pathogenesis. Lymphocystis disease virus isolated in China (LCDV-C) contains a putative homolog of cellular GPCRs, LCDV-C GPCR. In this paper, LCDV-C GPCR was cloned, and the subcellular localization and characterization of GPCR protein were investigated in fish cells. LCDV-C GPCR encoded a 325-amino acid peptide, containing a typical seven-transmembrane domain characteristic of the chemokine receptors and a conserved DRY motif that is usually essential for receptor activation. Transient transfection of GPCR-EGFP in fathead minnow (FHM) cells and epithelioma papulosum cyprini (EPC) cells indicated that LCDV-C GPCR was expressed abundantly in both the cytoplasm and nucleoplasm. Transient overexpression of GPCR in these two cells cannot induce obvious apoptosis. FHM cells stably expressing GPCR showed enhanced cell proliferation and significant anchorage-independent growth. The effects of GPCR protein on external apoptotic stimuli were examined. Few apoptotic bodies were observed in cells expressing GPCR treated with actinomycin D (ActD). Quantitative analysis of apoptotic cells indicated that a considerable decrease in the apoptotic fraction of cells expressing GPCR, compared with. the control cells, was detected after exposure to ActD and cycloheximide. These data suggest that LCDV-C GPCR may inhibit apoptosis as part of its potential mechanism in mediating cellular transformation.

In situ studies on the distribution patterns and dynamics of microcystins in a biomanipulation fish - bighead carp (Aristichthys nobilis)

The distribution and dynamics of microcystins in various organs of the phytoplanktivorous bighead carp were studied monthly in Lake Taihu, which is dominated by toxic cyanobacteria. There was a good agreement between LC-MS and HPLC-UV determinations. Average recoveries of spiked fish samples were 63% for MC-RR and 71% for MC-LR. The highest MC contents in intestine, liver, kidney and spleen were 85.67, 2.83, 1.70 and 1.57 mu g g(-1) DW, respectively. MCs were much higher in mid-gut walls (1.22 mu g g(-1) DW) than in hind- and fore-gut walls (0.31 and 0.18 mu g g(-1) DW, respectively), suggesting the importance of mid-gut wall as major site for MC absorption. A cysteine conjugate of MC-LR was detected frequently in kidney. Among the muscle samples analyzed, 25% were above the provisional tolerable daily intake level by WHO. Bighead is strongly resistant to microcystins and can be used as biomanipulation fish to counteract cyanotoxin contamination in eutrophic waters. (c) 2006 Elsevier Ltd. All rights reserved.

The recombinant beta subunit of C-phycocyanin inhibits cell proliferation and induces apoptosis

C-Phycocyanin (C-PC) from blue-green algae has been reported to have various pharmacological characteristics, including antiinflammatory and anti-tumor activities. In this study, we expressed the beta-subunit of C-PC (ref to as C-POP) in Escherichia coli. We found that the recombinant C-PC/beta has anti-cancer properties. Under the treatment of 5 mu M of the recombinant C-PC/beta, four different cancer cell lines accrued high proliferation inhibition and apoptotic induction. Substantially, a lower response occurred in non-cancer cells. We investigated the mechanism by which C-PC/beta inhibits cancer cell proliferation and induces apoptosis. We found that the C-PC/beta interacts with membrane-associated beta-tubulin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Under the treatment of the C-PC/beta, depolymerization of microtubules and actin-filaments were observed. The cells underwent apoptosis with an increase in caspase-3, and caspase-8 activities. The cell cycle was arrested at the G0/G1 phase under the treatment of C-PC/beta. In addition, the nuclear level of GAPDH decreased significantly. Decrease in the nuclear level of GAPDH prevents the cell cycle from entering into the S phase. Inhibition of cancer cell proliferation and induction of apoptosis may potentate the C-POP as a promising cancer prevention or therapy agent. (c) 2006 Elsevier Ireland Ltd. All rights reserved.

La2Zr2O7的增韧及陶瓷纤维的制备

La2Zr2O7是一种近年来才提出的新型热障涂层材料，该材料熔点高，在熔点以下不发生相变，热导率低，抗烧结及没有氧传输发生，这些特点使得它作为一种高温下应用的热障涂层材料越来越引起人们的重视。但是，由于该材料的热膨胀系数和断裂韧性比较低，它的实际应用受到了限制。 在本论文中，使用高压烧结的方法获得了致密化的纳米La2Zr2O7块体材料，并对其断裂韧性和热膨胀系数进行了研究。得到的La2Zr2O7纳米材料的断裂韧性和热膨胀系数分别为1.98MPam1/2和9.6×10-6K-1 (200-1000℃)，这些数值明显高于非纳米的La2Zr2O7陶瓷(断裂韧性和热膨胀系数分别为1.40 MPam1/2 和 9.1×10-6 K-1，该结果表明纳米化是一种提高材料断裂韧性和热膨胀系数的有效方法。在La2Zr2O7纳米粉末中加入8YSZ纳米颗粒，高压烧结后使其颗粒充分生长，在得到的复相化合物中观察到形成了类似棒状晶体的自增韧相，使得复合材料的断裂韧性(1.88 MPam1/2)比La2Zr2O7有所提高，甚至超过了同样条件下制备的8YSZ样品的断裂韧性。 La2Zr2O7的断裂韧性也可以通过在基体中添加BaTiO3铁电材料得到明显的提高。当添加BaTiO3的体积含量达到10vol％时，4.5GPa，1450℃高压烧结10min得到的复合材料断裂韧性达1.98 MPam1/2，明显高于同条件下烧结的La2Zr2O7 (1.60MPam1/2)。应力诱导下BaTiO3的电畴转向是主要的增韧原因。随着BaTiO3颗粒添加的体积含量增加，复相化合物的热膨胀系数也明显提高。当掺杂20vol％BaTiO3时，得到的复合材料平均热膨胀系数达到10.2×10-6K-1 (150~1200℃)。 我们通过在4.5GPa, 1650℃高压烧结5min的方法还获得了掺杂YAG纳米颗粒的La2Zr2O7纳米复相陶瓷。在室温下测量了材料的维氏硬度，并通过压痕裂纹长度计算出了材料的断裂韧性。随着YAG纳米颗粒体积含量的增加，纳米复相陶瓷的断裂韧性和维氏硬度都依次增加，当添加20vol％的YAG纳米颗粒时达到最大，分别为1.93 MPam1/2和11.45GPa。断裂韧性增加的机理可归结为以下三点：一是YAG纳米颗粒的添加提高了La2Zr2O7基体的晶界强度，二是基体晶粒尺寸变化的影响，三是YAG纳米颗粒对裂纹的偏转和钉扎作用。添加微米YAG颗粒的复相化合物因为和纳米复相陶瓷具有不同的增韧机制，因此断裂韧性的变化趋势也不相同，在掺入10vol％的YAG微米颗粒时，复合材料的断裂韧性最大，而后降低，当掺入YAG微米粒子的体积含量达到20vol％时，断裂韧性甚至低于La2Zr2O7。 从20世纪90年代开始，电纺作为一种合成纤维的办法越来越吸引人们的注意。其合成的纤维长度长，直径均匀，并且组成范围很广。最初，电纺只是被用来合成一些有机聚合物的纤维，最近，很多研究组开始致力于使用电纺的方法合成复合纤维或者陶瓷纤维。 在本论文中，我们使用电纺的方法获得了La2Zr2O7纳米纤维和SiC单晶纳米线。1000℃煅烧得到的La2Zr2O7纳米纤维具有烧绿石结构，直径在200~500nm之间。同样的温度煅烧时得到的La2Zr2O7纳米纤维的比表面积要明显高于粉末样品的，表明纤维的抗烧结性能比粉末的高。得到的SiC纳米线直径在50~100nm之间，表面有一约5nm厚的无定形的SiO2薄层。 使用电纺的方法，恰当的控制煅烧条件，我们获得了La2Ce2O7， La2(Zr0.745Ce0.386)2O7.524和8YSZ中空纤维。这种中空结构减小了粒子之间的接触面积，提高了材料的抗烧结性能。在扫描电镜分析的基础上，我们总结了这些中空纤维的形成过程。

基于硅基定向耦合器的单纤三向器设计

设计了基于硅基二氧化硅定向耦合器的光纤到户单纤三向器.通过定向耦合器耦合系数对波长的信赖性,在相同的耦合长度下实现单纤三向器三个波长(1310nm,1490nm和1550nm)的全周期耦合或半周期耦合,使三个波长信号从不同的耦合臂输出,完成三向器粗分波功能.有限差分束传播法(FD-BPM)模拟结果表明三向器损耗小于0.5dB,三个响应波长的1dB带宽即可满足ITU.984带宽要求,最优串扰为-14dB.

基于分布式内存数据库的HIRFL-CSR真空监控系统

This paper introduced a real-time vacuum monitor system based on multilayer Web architecture for HIRFL-CSR(Heavy Ion Research Facility of Lanzhou & Cooler Storage Ring) project in Lanzhou.It combined with COM/DCOM to develop the application layer,and developed the web layer with ActiveX and Ajax technology.It provided a facility and efficiency method for real-time control.The application shows that this system runs stably and accurately.中文文摘：简要介绍了国家"九五"重大科学工程——兰州重离子加速器冷却储存环(HIRFL-CSR)真空监控系统的总体结构,分析了在Web构架下,基于分布式内存数据库的多层真空监控系统的实现方法。采用分布式内存数据库,解决了基于Web构架的分布式实时应用环境下对系统和网络资源的消耗问题。在软件控制方面采用了统一调度,既简化了软件实现过程,又提高了系统的安全性、高效性和易维护性。该系统已成功运行。

Melting of Au and Al in nanometer Fe/Au and Fe/Al multilayers under swift heavy ions: A thermal spike study

Knowing that Fe is sensitive to swift heavy ion irradiations whereas Au and Al are not, the behavior of nanometric metallic multilayer systems, like [Fe(3 nm)/Au(x)](y) and [Fe(3 nm)/Al(x)](y) with x ranging between 1 and 10 mn, were studied within the inelastic thermal spike model. In addition to the usual cylindrical geometry of energy dissipation perpendicular to the ion projectile direction, the heat transport along the ion path was implemented in the electronic and atomic sub-systems. The simulations were performed using three different values of linear energy transfer corresponding to 3 MeV/u of Pb-208, Xe-132 and Kr-84 ions. For the Fe/Au system, evidence of appearance of a molten phase was found in the entire Au layer, provided the Au thickness is less than 7 nm and 3 nm for Pb and Xe ions, respectively. For the Fe/Al(x) system irradiated with Pb ions, the Al layers with a thickness less than 4 nm melt along the entire ion track. Surprisingly, the Fe layer does not melt if the Al thickness is larger than 2 nm, although the deposited energy surpasses the electronic stopping power threshold of track formation in Fe. For Kr ions melting does not occur in any of the multilayer systems.

The luminescence of Eu2+ in mixed phase system

The dependence of the structure of the hosts on the M ion radius in MMgAl10O17 (M = Be, Mg, Ca, Sr, Ba, Pb, Eu, Mn, Fe, Co, Ni, Zn, Cd, Sn) system was studied and the luminescence of Eu2+ the mixed phase system was discussed. When M ion radius is less than 0.10 nm, the system MMgAl10O17 constructs by the mixed phases consisting of manegtoplumbite and spinel, alpha-alumina or spinel and alpha-alumina. In the mixed phase of manegtoplumbite and spinel and alpha-alumina, Eu2+ ion preferentially occupies lattice site of the cations in manegtoplumbite well matched with the radius and charge of Eu2+. There exists only d-->f transition emission of Eu2+ and no characteristic emission of Eu3+ occurs in those hosts. In the mixed phase of spinel and alpha-alumina, Eu2+ can enter the lattice site of Mg2+ ion or Al3+ ion and the d-->f and f-->f transition of Eu2+ can been observed respectively. Meanwhile, since the radius and charge of matrix lattice ions substituted by Eu2+ do not match with those of Eu2+, the valence state of Eu2+ is unstable. Eu2+ is partly changed into Eu3+ and the emission of Eu3+ is obviously observed even under the condition of reduction atmosphere. If reaction temperature is more than 1 150 degrees C, Al2O3 forms alpha-Al2O3 structure, the f-->f transition of Eu2+ appears. If reaction temperature is less than 1 150 degrees C, a mixed phase of alpha-Al2O3 and gamma-Al2O3 is formed, the f-->f transition of Eu2+ disappears and a new band emission from d-->f transition of Eu2+ occurs.

Applications of improved 2-D numerical wave tanks in wave breaking

Song and Banner (2002, henceforth referred to as SB02) used a numerical wave tank (developed by Drimer and Agnon, and further refined by Segre, henceforth referred to as DAS) to study the wave breaking in the deep water, and proposed a dimensionless breaking threshold that based on the behaviour of the wave energy modulation and focusing during the evolution of the wave group. In this paper, two modified DAS models are used to further test the SB02's results, the first one (referred to MDAS1) corrected many integral calculation errors appeared in the DAS code, and the second one (referred to MDAS2) replaced the linear boundary element approximation of DAS into the cubic element on the free surface. Researches show that the results of MDAS1 are the same with those of DAS for the simulations of deep water wave breaking, but, the different values of the wavemaker amplitude, the breaking time and the maximum local average energy growth rate delta(max) for the marginal breaking cases are founded by MDAS2 and MDAS1. However, MDAS2 still satisfies the SB02' s breaking threshold. Furthermore, MDAS1 is utilized to study the marginal breaking case in the intermediate water depth when wave passes over a submerged slope, where the slope is given by 1 : 500, 1 : 300, 1 : 150 or 1 : 100. It is found that the maximum local energy density U increases significantly if the slope becomes steeper, and the delta(max) decreases weakly and increases intensively for the marginal recurrence case and marginal breaking case respectively. SB02's breaking threshold is still valid for the wave passing over a submerged slope gentler than 1 : 100 in the intermediate water depth.

湖北徐家山锑矿床地球化学和成矿机理研究

　　湖北省通山县的徐家山锑矿床赋存于上震旦统灯影组和陡山沱组的海相碳酸盐岩中，该矿床是华南锑矿带内典型代表性锑矿之一，也是湖北最具经济价值的锑矿床。本论文以该矿床为研究对象，在系统整理前人工作的基础上，进行了深入细致的野外地质考察和系统采样，选取有代表性的样品，运用流体地球化学、元素地球化学、同位素地球化学（C、O、Sr、S、Pb、Sm-Nd）等方法手段，对其成矿流体来源、成矿物质来源、成矿时代、矿床成因等主要矿床学问题进行了系统研究，探讨了该矿床的成矿机理，并对华南锑矿带内上震旦统锑资源潜力进行了初步评价。本论文主要取得以下几点认识： 1）通过对该矿床成矿期脉石矿物（石英、重晶石和方解石）中包裹体镜下观察、显微测温和激光拉曼探针分析，表明该矿床为典型的中低温（150～200℃）热液锑矿床，其热液属NaCl + H2O + CO2 ± N2型，具低盐度（3～6% NaCl）和中等密度（0.90～0.96 g/cm3）特征。结合氢、氧、锶、铅同位素等研究结果，进一步推断这种成矿流体主要来源于经深部循环演化的大气降水，不支持其主要来源于岩浆期后热液的观点。 2）该矿床成矿前和成矿期方解石碳、氧同位素研究结果，表明成矿流体中的溶解碳以H2CO3为主，该流体与围岩发生水－岩相互作用是导致成矿期方解石和辉锑矿沉淀的主要机制。结合方解石的稀土元素地球化学研究，可推断该矿床的两期方解石为同源不同期的产物。 3）微量元素、碳、氧、硫同位素研究结果，表明徐家山矿床的成矿物质与赋矿围岩具有亲缘性；其中最主要的矿石矿物—辉锑矿，其硫同位素组成（+11.2‰～+14.4‰）相对较高（平均值可能在华南锑矿带内最高）、极其均一，且塔式效应明显等为特征，指示该矿的赋矿围岩—震旦纪海相地层是硫的唯一来源。 4）对徐家山锑矿床首次利用锶、铅同位素示踪其成矿物质来源。利用铅同位素示踪手段，首次明确提出该锑矿床存在两个矿源层，部分成矿物质来自赋矿围岩，部分成矿物质来自下伏基底地层，突破了前人对成矿物质仅来源于赋矿围岩的传统认识；并从锶同位素角度，进一步论证了下伏的中元古界冷家溪群基底是成矿元素锑的重要提供者。 5）首次对徐家山矿区成矿期方解石的Sm-Nd同位素组成进行了测定，并初步获得三条等时线年龄（323Ma、348Ma和402Ma）。结合该矿辉锑矿的正常铅模式年龄及成矿地质背景，可推断出该矿床应形成于加里东期。该结论否定了前人燕山期成矿的观点，为重新认识该矿的矿床成因和成矿机理提供新的契机。 6）徐家山锑矿床的成矿时代与那些江南古陆中赋存于前寒武系的锑（和/或金）矿床一致，其成矿流体特征与华南锑矿带其它典型锑矿床相似，揭示出华南锑矿带内不同地段、不同层位产出的锑矿床存在某种共性，这有助于揭示我国华南锑矿带不同锑矿床之间的内在联系以及该矿带锑大规模成矿的机制。 7）根据前人和本文的研究成果，重新厘定了徐家山锑矿床的成因类型，明确提出该锑矿为沉积－改造型矿床，层控特征非常明显。 8）初步评估华南地区上震旦统中锑矿的找矿潜力。认为华南锑矿床带中上震旦统，尤其是鄂南、赣西北、湘西等地的该套地层，锑资源潜力巨大。华南锑矿带中的上震旦统有可能成为我国将来找锑矿取得突破的重要层位之一。

有机质在贵州晴隆大厂锑矿成矿过程中的作用

锑成矿中有机作用的研究国内外进行得极少，本文首先运用（有机）包裹体探讨了大厂锑成矿流体的一系列物理化学性质和主要成矿特征：1．成矿温度与盐度分别为150-180℃ 和10-12 Wt%，2．主成矿阶段水质类型属 F-SO_4Ca－K型，气相成份中甲烷含量较高(C_1/C_2～C_4 > 1)，3. 成矿介质水主要来自大气降水，δD＝-63～-66‰, δ~(18)O = -3.5～-0.6‰)。有机地球化学研究显示岭好组有机碳含量高（平均 Corg = 0.71% > 0.5%)，完全具备生油能力，是一重要的烃源层。有机质反射率（Ro）达1.87-2.93%，演化程序较高，热变沥青多呈充填状，具明显的运移特征。模拟实验证明石油对锑有较强的萃取能力，可作为 Sb 迁移的良好载体；且按萃取实验结果，有机迁移与无机迁移同等重要。对腐殖酸（质）和高硫原油作了较详细的讨论－－腐殖酸（质）在形成矿源层中有重要作用，高硫原油热裂解本身可以产生H_2S，提供部份硫；而辉锑矿的最终形成则缘于大气降水的加入，温度降低和氧化等因素综合作用的结构。总结不同阶段不同有机质的不同作用，提出了有机－无机综合成矿模式。

Walking in old age and development of metabolic syndrome: the health, aging, and body composition study.

BACKGROUND: The specific health benefits of meeting physical activity guidelines are unclear in older adults. We examined the association between meeting, not meeting, or change in status of meeting physical activity guidelines through walking and the 5-year incidence of metabolic syndrome in older adults. METHODS: A total of 1,863 Health, Aging, and Body Composition (Health ABC) Study participants aged 70-79 were followed for 5 years (1997-1998 to 2002-2003). Four walking groups were created based on self-report during years 1 and 6: Sustained low (Year 1, <150 min/week, and year 6, <150 min/week), decreased (year 1, >150 min/week, and year 6, <150 min/week), increased (year 1, <150 min/week, and year 6, >150 min/week), and sustained high (year 1, >150 min/week, and year 6, >150 min/week). Based on the Adult Treatment Panel III (ATP III) panel guidelines, the metabolic syndrome criterion was having three of five factors: Large waist circumference, elevated blood pressure, triglycerides, blood glucose, and low high-density lipoprotein (HDL) levels. RESULTS: Compared to the sustained low group, the sustained high group had a 39% reduction in odds of incident metabolic syndrome [adjusted odds ratio (OR) = 0.61; 95% confidence interval (CI), 0.40-0.93], and a significantly lower likelihood of developing the number of metabolic syndrome risk factors that the sustained low group developed over 5 years (beta = -0.16, P = 0.04). CONCLUSIONS: Meeting or exceeding the physical activity guidelines via walking significantly reduced the odds of incident metabolic syndrome and onset of new metabolic syndrome components in older adults. This protective association was found only in individuals who sustained high levels of walking for physical activity.