抚仙湖无机污染物化学背景值及动物体内致突变性评定

为了比较抚仙湖不同区域的水质及其致突变性, 从抚仙湖周围水域采取7 个样点的水样。用电感 耦合氩等离子发射光谱法对水样中的无机污染物作定性和定量分析。另外使用蝌蚪( B uf o buf o andrewsi) 红细 胞微核试验检测抚仙湖水样的致突变性。结果显示: 禄冲采样点水样带有微核的红细胞率增高, 表明这个点水 样有致突变活性物质。

群组通信环境中的密钥管理协议

随着群组通信业务的普及，群组通信的相关安全研究也随之兴起。群组密码学的概念首先由 Desmedt 提出。与传统通信中的密码学方案相比，群组密码学具有很多优点，并已经成功地运用到视频点播和分布式系统等一些应用场景中。群签名，环签名，广播加密等密码学体制作为群组密码学的重要分支都得到了学术界的密切关注。本文的研究工作集中在群组密码学的一个重要组成部分：群组密钥管理，即多个（群组）用户在不安全的开放网络环境中通过一定的协议产生一个共享的会话密钥，为后面的通信提供各种安全性保护。 本文的研究工作主要包含两个方面，群组密钥分发协议和可证明安全的认证群组密钥协商协议。在对已有的群组密钥管理方案进行了大量的调查与分析后，我们在此基础上提出了一些有价值的研究成果。本文的主要成果包括： 1. 在第二章中，提出了一种高效的长期 self-healing 群组密钥分发方案。和已有方案相比，新方案的优势包括：（1）我们避免了使用指数运算, 而只是域上多项式的相关运算；（2）群组管理者广播消息次数比 Staddon 等人和Blundo 等人的方案少一次；（3）用户端存储私钥数目比 Staddon 等人的方案少将近一半；（4）新协议的安全性为无条件安全。 2. 在第三章中，构造了一个从一般群组密钥协商协议向基于口令认证的群组密钥协商协议转换的编译器。编译器的构造利用了对称加密体制，NM-CCA2 和 IK-CCA2 安全的公钥加密体制，以及 UF-CMA 安全的数字签名体制，从而使得编译器可以避免在线/离线字典攻击。 3. 在第四章中，提出了一个基于口令认证的群组密钥协商协议，使得网关在认证服务器的协助下和多个用户之间建立一个会话密钥，同时认证服务器不知道此会话密钥的任何信息（网关和认证服务器之间的信道是专用信道）。由于意识到口令的泄露往往是由于用户的不当使用造成的，所以，不同于已有的基于口令认证的门限密钥协商机制，我们的门限方案是在用户端实施。我们的门限方案要求把用户群组和认证服务器预先共享的口令（称之为群组口令）以秘密共享方式分散共享在群组用户之间，并且每个用户所存储口令的子秘密（share）值依然是一个易记忆的口令（称之为用户口令）。只有不少于 k 个用户一起才能恢复出群组口令。 4. 在第五章中，利用了Unified 模型（把用户长期私钥嵌入到密钥协商过程）构造了一个在 Strong Corruption 模型下可证明安全的强健的认证群组密钥协商协议。和已有类似方案相比，新方案所需要的签名数量明显减少，从而，计算复杂度和通信复杂度也随之降低。另外，新协议是在 Strong Corruption 模型下可证明安全，在此模型下的类似协议比较少。 5. 在第六章中，对 Desmedt 等人提出的 BD-II（树型）群组密钥协商协议做出改进。利用在树中各个节点上应用遮罩函数，我们把由于群组关系变化而对密钥更新所产生的影响限制在一个比较小的群组范围中，从而提高了协议在动态情况下运行的效率。新协议通过四个子算法：初始化，成员加入，成员撤销，子群组合并来分别应对群组密钥协商过程中所遇到的各种（动态）情况。

川西亚高山两种针叶树幼苗对增温和施氮的响应

人类活动引起全球大气中温室气体（CO2、CH4、NOx）浓度不断增加，致使地球表面温度在过去的100 年中已经增长了0.74 ± 0.18℃，预计到本世纪末将会增加1.1-6.4℃。此外，氮沉降也是当今社会的重要环境问题，随着经济发展的全球化, 高氮沉降也呈现出全球化趋势。全球气候变暖和氮沉降给陆地生态系统的地上、地下生物学和生物地球化学过程所带来巨大影响越来越引起人们的关注。 本文以川西亚高山针叶林的两个重要树种云杉和油松幼苗为研究对象，采用红外辐射增温（空气增温2.1℃，土壤增温2.6℃）和根部施氮（施氮量25 g N m-2yr-1）的方法，从生长形态、光合作用、抗氧化能力和矿质营养等方面研究这两种幼苗对气候变暖和氮沉降的响应。该实验为室外控制实验，包括四个处理：(1)不增温+不施氮（UU）；(2) 不增温+施氮（UF）；(3) 增温+不施氮（WU）；(4) 增温+施氮（WF）。本研究旨在从生理生化、物质代谢 、生长及形态等不同水平上研究模拟增温和施氮对两种树苗的联合效应，提高我们对全球变化下亚高山针叶林早期更新过程的理解，同时也为森林管理提供科学依据。具体研究结果如下： 单独增温处理显著提高了云杉和油松幼苗的地茎、叶重、茎重、根重以及总生物量；单独施氮处理也增加了两种幼苗的株高和总生物量。而增温和施氮联合作用对两种幼苗生长的影响并不相同，联合作用对云杉幼苗生长指标的正效应显著低于单独施氮处理，但是联合作用比单独增温或施氮更大程度的促进了油松幼苗生物量的积累。 单独增温和施氮都有利于提高云杉和油松叶片中叶绿素含量、净光合速率(A)、最大净光合速率(Amax)、表观量子效率（Φ）、最大光能转化效率（Fv/Fm）和量子产量（Y）。与对两种幼苗生长指标的影响相似，加氮和增温共同作用下油松幼苗的以上光合指标比在单独增温或施氮处理下有更大程度的提高；而联合作用下云杉幼苗叶绿素含量、净光合速率、最大净光合速率、表观量子效率、最大光能转化效率以及量子产量比单独施氮处理明显地降低。 增温和施氮都显著地降低了云杉和油松幼苗针叶组织中活性氧和丙二醛的积累。交互作用降低了云杉幼苗叶片的抗氧化酶活性、脯氨酸和ASA 的含量，却显著提高了油松幼苗SOD、POD、APX 等抗氧化酶的活性，并且对油松幼苗脯氨酸和ASA 积累的促进作用比单一因子更加明显。因此，增温和施氮共同作用下油松幼苗叶片中O2-产生速率、H2O2 及MDA 含量明显降低，而云杉叶片中只有O2-产生速率出现降低趋势。 增温和施氮都降低了云杉体内的P、Ca、Mg 元素的含量，增加了Cu、Zn、Mn 在各器官内的积累。对油松幼苗而言，增温和加氮单独作用也显著降低了Ca 含量增加了Cu、Zn、Mn 的积累，但是不同于云杉幼苗的是P、Mg 也显著增加。增温和施氮联合作用对云杉幼苗体内元素的影响与单一施氮处理或增温处理相似，不同的是比单一因子作用更为明显降低了P、Ca、Mg 含量，增加了植株中N、Cu、Zn、Mn 的含量，但是油松矿质元素含量在联合作用下并没有产生类似于云杉幼苗的双因子叠加效应。 总之，尽管单独增温或者施氮都有利于云杉和油松幼苗生长指标、光合能力以及抗氧化能力的提高。但是，增温和施氮对云杉幼苗生长生理的促进效应非但没有在交互作用下有更大的提高，反而低于单独氮处理。与此不同的是，增温和施氮联合作用比单因子作用更有利于油松幼苗生长及生理指标的提高。 With the continued increase in atmospheric concentrations of greenhouse gases (CO2、CH4、NOx), the mean global surface temperature has increased by about 0.74 ± 0.18℃ over the past century and is predicted to rise by as much as 6.4℃ during this century. Besides global warming, nitrogen deposition is another serious environmental problem caused by human activities, and high nitrogen load has become globalization as a result of global economy development. Global climate warming and nitrogen deposition have induced dramatic alternations in above - and below- ground biology and biogeochemistry process in terrestrial ecosystems, and more and more attention has been invited to those problems. This experiment mainly studies two important species Picea asperata and Pinus tabulaeformis in subalpine coniferous forest of western Sichuan, China. Infared heaters are induced to increase both air and soil temperature by 2.1℃ and 2.6 ℃, respectively. Ammonium nitrate solution (for a total equivalent to 25 g N m-2 year-1) is added to soil surface. There are four treatments in this study: (1) unwarmed unfertilized (UU); (2) unwarmed fertilized (UF); (3) warmed unfertilized (WU); (4) warmed fertilized (WF). This study is conducted to determine the influences of experimental warming and nitrogen fertilization on physiolchemistry, nutrition metabolism, growth and morphology in the two coniferous species seedlings. The current study is favorable for increasing our understanding on the early phase of regeneration behavior in subalpine coniferous forest, and it also provide scientific direction for forest management under future global changes. The results are as follows: Artificial warming alone significantly increased basal diameter, leaf mass, stem mass, root mass and total biomass for Picea asperata and Pinus tabulaeformis seedlings, and single nitrogen fertilization are also favorable for growth of the two species and stimulate plant hight and total biomass. The two species seedlings respond differently to the combination of elevated temperature and nitrogen addition. Warming combined with nitrogen fertilization weakens the positive effects of nitrogen addition for growth of Picea asperata seedlings. However, the combination of elevated temperature and nitrogen fertilization further increase biomass accumulation of Pinus tabulaeformis seedlings. Both elevated temperature alone and nitrogen fertilization alone can increase photosynthetic pigments contents, net photosynthetic rate (A), maximum net photosynthetic rate (Amax), apparent quantity yield (Φ), maximum photochemical efficiency of photosystem II (Fv/Fm) and effective quantum yield (Y). Similarly with growth parameters, the combination of warming and nitrogen addition induced more increment of these above photosynthetic parameters for Pinus tabulaeformis seedlings. However, these photosynthetic parameters of Picea asperata seedlings under the combination of warming and nitrogen addition are lower than those under nitrogen fertilization alone. The levels of active oxygen species (AOS) and malodiadehyde (MDA) in needles of the two coniferous species seedling are obviously decreased by experimental warming or additional nitrogen. Warming combined with nitrogen fertilizer reduces the activities of SOD, CAT and APX, and the contents of proline and ASA of Picea asperata seedlings, but the combination significantly increases activities of these antioxidant enzymes in needlels of Pinus tabulaeformis seedlings and further improves the accumulation of proline and ASA compared to either artificial warming or nitrogen addition. Therefore, the rate of O2 - production, the contents of H2O2 and MDA in needles of Pinus tabulaeformis seedlings are remarkably reduced by the combination of warming and nitrogen addition, but the combination only significantly decreased the rate of O2 - production of Picea asperata seedlings. Elevated temperature or nitrogen fertilization decrease the contents of P, Ca, Mg but increase Cu, Zn, Mn contents for Picea asperata seedlings. For Pinus tabulaeformis seedlings, elevated temperature alone and nitrogen fertilization alone decreased Ca, but increased P, Mg, Cu, Zn, Mn contents. The effects of the combination of warming and nitrogen addition on these element contents in needles of Picea asperata seedlings are added or multiplied the effects of warming and nitrogen addition alone, resulting in less contens of P, Ca, Mg and more contents of Cu, Zn, Mn than either elevated temperature or nitrogen fertilization. Howere, these adding or multipluing single-factor effects on contents of these elements are not observed in the case of Pinus tabulaeformis seedlings. In conclusion, growth parameters, photosynthetic capacities and antioxidant abilities of Picea tasperata and Pinus abulaeformis seedlings are improved by experimental warming or nitrogen fertilization. Interestingly, the positive effects of warming and nitrogen addition on growth and physiological performances are not multiplied by the combination of elevated temperature and nitrogen fertilization, even dempened for Picea asperata seedlings. However, for Pinus tabulaeformis seedlings, growth and physiological performances are further improved by the combination.

Band properties of the transitional nucleus Pt-189

High-spin states in Pt-189 have been studied with the in-beam gamma-spectroscopy method via the Yb-176(O-18, 5n) reaction at beam energies of 88 MeV and 95 MeV. A new level scheme of Pt-189 has been established. Rotational bands based on the upsilon i(13/2)(-1), upsilon f(5/2)(p(3/2)) and upsilon i(13/2)(-2)upsilon f(p(3/2)) configurations, as well as several structures with irregular level spacings, have been observed. Properties of rotational bands have been analyzed in the framework of triaxial particle-rotor model. A gamma similar to -30 degrees triaxial shape and a near prolate shape have been proposed to the upsilon i(13/2)(-1) and uf(5/2)(p(3/2)) bands, respectively. Two Delta I=2 transition sequences with similar energies have been observed, and they have been proposed to be associated with the upsilon i(13/2)(-1)upsilon f(5/2)(p(3/2)) configuration. According to the relevant Nilsson orbitals, the bands built on the upsilon i(13/2)(-1)upsilon f(5/2)(p(3/2)) configuration could be interpreted as a pair of pseudo-spin partner.

工业化将推动缓释长效尿素的应用

<正>自1955年合成微溶性脲醛化台物(UF)以及1967年聚合物包膜肥料投入生产,缓／控释肥料的生产已有40多年的历史。自上世纪70年代以来,国内外已推出了数十种缓释、控释肥料,这些高新技术,可以较好地控制肥料养分释放速度,氮素利用率高达60％-70％,而且不受土壤类型等复杂因素的影响,被称为"21世纪的肥料"。中国科学院沈阳应用生态研究所自上世纪八十年代初在国内率先开展长效尿素的研究,在新型肥料研究开发方面取得了多项成果,其中"长效尿素的研究"获辽宁省科技进步一等奖(1988年),"长效碳酸氢铵的研制与推广"项目先后获得中国科学院科技进步特等奖、国家科技进步二等奖;"脲酶／硝化抑制剂对尿素氮行为的协同作用机理及其在缓控释肥料中的应用"成果,2002年通过了鉴定结论是:在同类研究中居于国际先进水平,部分领域达到国际领先水平。研究的"复方长效尿素"获得了国家发明专利。

Development of a LCST membrane forming system for cellulose acetate ultrafiltration hollow fiber

A novel lower critical solution temperature (LCST) membrane forming system containing cellulose acetate (CA)/poly (vinyl pyrrolidone) (PVP 3 60K)/N-methyl-2-pyrrolidone (NMP)/1,2-propanediol with a weight ratio of 24.0:5.0:62.6:8.4 had been developed. CA hollow fiber ultrafiltration (UF) membranes were fabricated using the dry-wet spinning technique. The fibers were post-treated with a 200 mg/L hypochlorite solution over a period of 6 It at pH 7. The experimental results showed that water flux of a membrane decreased while retention increased with increasing CA concentration in a dope. It was concluded that the membrane pore size decreased with increasing CA concentration. The membrane fouling tendency for BSA was 3 times higher than that for PVP 24K. (C) 2004 Elsevier B.V. All rights reserved.