线性低密度聚乙烯和聚苯乙烯共混物的原位增容及其形态/结构和性能

用反应挤出方法制备了线性低密度聚乙烯 /聚苯乙烯 (LLDPE/PS)合金材料。为了增加两相间的相容性 ,采用了 Al Cl3作为催化剂引发烷基化反应。由于在反应挤出过程中原位形成了 LLDPE-g-PS接枝共聚物 ,该合金材料的抗冲击性能和韧性得到很大的提高。当 m(LLDPE)∶m(PS)为 80∶ 2 0时 ,与相同组成的用简单物理共混的 LLDPE/PS相比 ,其悬臂梁冲击强度由 88.5 J/m增加到 40 1 .6J/m,断裂伸长率由 3 70 %提高到 790 %。对经四氢呋喃抽提后的接枝共聚物用拉曼光谱进行了表征 ,发现聚乙烯分子链接枝到聚苯乙烯的苯环对位上。用扫描电镜观察了反应共混体系和简单物理共混物的形态 ,前者分散相的尺寸小于 1 μm,后者分散相的尺寸则较大 ,一般为 3～ 4μm。对反应共混体系中聚乙烯的结晶行为的研究结果表明 ,该体系中的 LLDPE产生了分步结晶现象 ,这可以解释为体系中接枝共聚物的存在对 LLDPE的结晶有抑制作用

系列新型咔哚聚芳醚砜结构的裂解色谱-质谱研究

利用裂解色谱-质谱对4个同一系列新型咔哚聚芳醚砜样品的裂解规律进行了研究,分别得到了各自链节的裂解特征碎片,证明了各聚合物确实发生了缩聚反应.

ELECTROCHEMICAL-BEHAVIOR OF N-METHYL-N'-HEXADECYLVIOLOGEN MONOLAYERS ON SILVER ELECTRODES - EFFECTS OF COUNTERIONS

N-Methyl-N'-hexadecylviologen (C16MV) has been the subject of several electrochemical and spectroelectrochemical studies which characterized the species present in various redox states for C16MV monolayers on silver electrode surfaces. Both self-assembled monolayers (SA) and Langmuir-Blodgett (LB) transferred systems have been studied. These indicated inconsistencies regarding the presence or absence of splitting of the first reduction peak in its cyclic voltammogram (CV). The present study demonstrates the important influence of the specific anionic species present in the supporting electrolyte. Splitting may or may not take place, depending on the size and relative strength of the adsorption of specific anions contributed by the supporting electrolyte. Small, strongly adsorbing anions such as iodide produced peak splitting in the CV of C16MV monolayers; bulky but weakly adsorbing anions such as perchlorate may disrupt the ordered structure of monolayers but produce no splitting. Ancillary data provided by surface enhanced Raman spectroscopy (SERS) was consistent with the electrochemical measurements.

滤食性贝类筏式养殖对浅海生态环境影响的基础研究

近年来，由于对海区不合理的开发，我国浅海贝类筏式养殖接连遭受重创，这亟需从理论上和实践中确定养殖容量和养殖模式。本文在我国北方典型养殖海湾四十里湾对筏式养殖的贝类开展了现场生理生态学研究，对贝类对浮游植物等悬浮颗粒物的处理过程即贝类对颗粒有机物及营养元素C、N、P的摄食、吸收、排泄、排粪和生长进行了剖析，分析了贝类在沿岸养殖生态系中的物质和营养循环中所扮演的角色，为海区贝类养殖容量和养殖模式的最终确定提供了基础数据。另外，本文还对海水、沉积物及生物体中磷的分析方法进行了大量的实验工作。主要结果如下：① 比较系统地评述了双壳贝类的生物沉积(biodeposition)的原理、测定方法及其生态效应。贝类通过生物沉积在沿岸生态系中的物质和营养循环中扮演着重要的角色。国际上已有不少研究专门报道了贝类在海区现场的生物沉积。而在我国，这方面的研究却罕见。② 综述了双壳贝类各种形态的 N 和 P 排泄及其生态效应。对于我国广泛养殖 的栉孔扇贝、海湾扇贝和牡蛎等双壳贝类的TDN、TP排泄尚未见报道。 ③ 在6～7月，在四十里湾的不同养殖海区(8个站位)对扇贝的生物沉积进行了现场测定。在整个四十里湾海区，一龄栉孔扇贝(壳高 41.1±4.1mm，软体干重 0.48±O.10 g/ind))每个每天所产生生物沉积物干重平均为59.9mg，对颗粒有机质(POM)、颗粒有机碳(POC)、颗粒有机氮(PON)和颗粒有机磷(POP)的生物沉积速率范围及平均值分别为： 6.88、3.09、0.392 和 0.022mg/ind·d。还在一个站位测定了海湾扇贝(壳高 24.6±2.3mm；软体干重 O.14g/ind)的生物沉积速率为 24.3mg/ind·d，或179.2mg/g·d。不同站位一龄栉孔扇贝的生物沉积速率有较大变化，这主要与饵料浓度不同有关。二龄栉孔扇贝(壳高60.9±8.2mm；软体干重1.91±0.32 g/ind)的生物沉积速率平均为 112.7mg/ind·d，对POM、POC、PON和POP的沉积速率分别是一龄扇贝的1.85倍、1.68倍、1.77倍和2.33倍。养殖海区与非养殖海区比较，前者近海底沉积速率是后者的 1.51～3.47 倍。根据以上数据，作者计算了中等规格栉孔扇贝(用壳高 41.1±4.8mm 扇贝估算)在四十里湾在夏季每天的生物沉积量达 162 吨(干重)，或18.6tPOM、8.37tPOC、1.06tPON和60kgPP。在四十里湾的贝类筏式养殖海区，可以估计贝类每年因生物沉积的生产而循环427tN和98.OtP(包括20.0t OP的贡献)，它们能分别满足浮游藻类生产所需求N和P的17.0％和28.3％(其中OP贡献 6.9％)。可见，贝类在养殖生态系的物质和营养盐循环中扮演着重要的角色。高密度、大面积的贝类养殖使大量的生物沉积物聚集于海底，可能对海区环境产生冲击。作者分析，98年8月份烟台养殖区赤潮的发生很可能与海底生物沉积物营养盐的快速释放以及栉孔扇贝大面积死亡而使浮游藻类失去了摄食控制有关，而风平浪静和养殖笼对水流的阻挡也为赤潮的发生提供了有利条件。④ 采用半现场流水系统法测定了栉孔扇贝在不同养殖密度、不同养殖模式(扇贝单养、贝藻混养、贝藻参混养)中的生物沉积。实验时间尺度大，前后计80天。结果说明扇贝的生物沉积速率与其养殖密度呈反比关系。养殖密度的高低影响饵料浓度的变化(两者呈负相关的对数函数关系)，而饵料浓度的高低直接决定着扇贝的生物沉积速率的高低，两者呈正相关关系(生物沉积速率与POC和叶绿 a 分别呈对数和指数函数关系)。不仅生物沉积物的数量与养殖密度(或饵料浓度)有关，生物沉积物的质量同样与养殖密度(或饵料浓度)有关。栉孔扇贝的养殖使沉积物的有机质含量及C、N 和 P 含量降低，且密度越高，它们的含量越低。这反映了扇贝对环境的适应能力。在海带和扇贝的混养模式中，海带对扇贝生物沉积物的数量和质量不构成影响，当然这是在海带不影响浮游植物数量的前提下得出的结果。而实际上在自然海区两者可能是竞争关系。⑤ 对从海区取回到实验室的多种滤食性动物，包括经济双壳贝类(栉孔扇贝、海湾扇贝、长牡蛎、贻贝、菲律宾蛤仔等)和养殖中的污损动物(栖海鞘、玻璃海鞘、藤壶、玟斑稜蛤)的 N 和 P 排泄进行了测定，包括排泄成分和排泄速率。在N排泄中，NH_4-H 占主要部分，如笼式养殖的双壳贝类 NH_4-N 占总N排泄的70％以上，平均值范围为70.8～80.1％。氨基酸是第二大排泄成分，平均占总N排泄的10～25％。其它形态的N，如尿素、亚硝酸盐和硝酸盐也有检出，如双壳贝类尿素氮在总氮排泄中占 2～5％。但在双壳贝类中未检出尿酸氮。比较而言，海鞘、藤壶的尿素氮相对高一些。在P排泄中，OP约占TDP排泄的15～27％。栉孔扇贝TDP排泄速率为0.281μmol/h·ind。作者以实验室测定结果计算，在整个四十里湾的夏季，所养殖的双壳贝类每天将排泄4.54t总溶解氮，其中NH_4-N 3.36t、Amino-N 0.69t、Urea-N 0.2t。 同时每天磷的排泄为0.57t TDP，其中OP O.15t。对面积为1.3 * 10~4hm~2的海区而言，贝类的N、P排泄分别能满足浮游植物生产所需N、P的44％和40％。尽管Urea-N所占比例有限，但也能满足海区浮游植物所需 N 的 2％左右。以上说二月高密度的贝类养殖对海区生态系统营养盐循环的影响是很显著的。附着动物(柄海鞘等)的N、P 排泄也不容忽视，它们分别能满足浮游藻类生产所需 N、P 的 ll％和 12％。它们一方面通过排泄和排粪加速营养盐和物质的循环对浮游植物的生长产生刺激作用；另一方面，对藻类产生摄食控制，如果海区中滤食性动物太多，即使营养盐再丰富也难以使浮游植物大量繁殖，这无疑将影响滤食性动物的生长速率。⑥ 运用近年来发展起来的生物沉积法对四十里湾半现场流水系统中贝类的滤水率、吸收率、生长率、生态效率等生理生态学参数进行了测定。栉孔扇贝(收获时规格0.194～0.412g软体干重/ind)滤水率平均为3.65 1/ind·h。扇贝放养密度和饵料浓度没有显著关系。扇贝的总摄食率平均为3.98mg/ind·h，对POM、POC、PON的 摄食率范围为0.84～1.87、0.335～0.748、0.0515～O.1293mg/ind·h。扇贝的摄食率随放养密度的升高而降低，与POM呈正相关关系。扇贝的吸收速率受密度和饵料浓度的影响不明显。扇贝对N的吸收效率较C、P稍高，对总有机质的吸收效率为75.9±4.1％，如此高的吸收效率与低饵料浓度有关。扇贝氨基酸泄漏所损失的能量高于排氨的能量损失。代谢能与吸收能呈明显的正相关关系。SFG与饵料浓度呈正相关关系。总生长效率K1(* 100)变化较大，范围为20～49；净生长效率K，K_2(* 100)随POM的升高而升高。扇贝对N的总生态效率范围为6.2～12.8％(平均9.9％)，这高于对C(平均5.9％)和P(平均4.1％)的总生态效率。扇贝对POC、PON和PP的生长余力(SFG_C、SFG_N、SFG_P)平均分别为197、46.8和6.2μg/ind·h，它们分别与POC、PON和PP呈正比关系。扇贝对N的净生长率高于对C和P的净生长率。在N的预算中，如果仅考虑NH_4-N的排泄而忽视其它形态氮的排泄，将会产生很大偏差(平均约20％)。扇贝贝壳生长所需的能量在整个扇贝生长所需能量的9.0～15.1％(平均 11.2％)；贝壳C、N和P在扇贝生长中所占的比例分别为10.5～17.8％、9.4～16.1％和8.7～15.O％。可见，贝壳不管在能量预算还是在元素预算中都不应该被忽视。理论计算而得到的SFG和SFG_C、SFG_N、SFG_P与扇贝的实际生长和扇贝C、N、P的实际增长量之间呈正相关关系，但前者明显过高地估计了扇贝的生长。⑦ 运用生物沉积法在四十里湾养殖海区现场对栉孔扇贝的生理生态学特征进行了研究。不同海区扇贝的滤水率有变化，一龄扇贝(41.1±4.1mm，软体干重 0.48±O.10g/ind)滤水率变化范围为 0.72～2.54(平均 1.27)1/ind·h 或 1.65～5.97(平均 2.61)1/g·h。与半现场研究结果一致，滤水率与TPM没有明显关系，而摄食率却与TPM呈正相关关系。二龄扇贝(软体干重 1.91±0.32g/ind)滤水率为 2.09～3.99(平均 3.10)1/ind·h。吸收速率与POM(或TDM)呈正相关关系，与饵料质量(POM/TPM)无明显的相关关系。吸收效率AE_(POM)与TPM(或POM)没有相关关系，却与饵料质量呈明显 的正相关关系。扇贝对POC、PON和PP的吸收效率平均分别为68.9％、64.0％和63.6％。不同海区SFG差别很大。一龄扇贝SFG范围为-O.174～24.08 J/ind·h，SFG与饵料浓度POM呈正相关关系。SFG负值的出现主要与低饵料浓度有关。SFG_C、SFG_N、SFG_P分别与POC、PON和PP呈正相关关系。在N的生长余力计算中，如果仅考虑NH_4-N排泄，而不考虑其它形态N的排泄，就可能产生相当大的偏差，偏差范围为11～360％，这高于半现场的偏差值，显然SFG_N越低，产生的偏差就越大。这说明在饵料不足、扇贝生长受到限制的环境下进行N生长余力的计算时必须考虑其它形态N的排泄。⑧ 对四十里湾养殖海区一些双壳贝类和藻类的化学组成和有机净生产量进行了讨论。不同双壳贝类的软体有机碳含量差别不大，而N含量差异较大。栉孔扇贝N含量最高(占软体干重的12.36％)，而牡蛎、毛蚶软体N含量相对较低，为 8～9％。从双壳贝类贝壳的组成来看，贻贝和菲律宾蛤仔贝壳中N含量最高，分别为 0.55％ 和 0.56％；而栉孔扇贝贝壳N含量相对较低，在 O.1％左右。贻贝贝壳有机磷含量 (308ppm) 也明显高于栉孔扇贝贝壳(62.1 ppm)。不同海区海带的 C/N 比值较高，变化明显，范围为17.36～30.23。石莼与此相似。大型藻类高 C/N 比值说明海区营养元素N的不足。海带的不同部位N含量差别很大，中带部和边叶在不同海区有较大变化，即对环境的营养状况比较敏感。紫贻贝贝壳中C、H、N 和 P 的含量在整个贻贝中占有相对大的比例，分别为 30.4％、30.2％、31.8％和 29．6％。

C, N and P regeneration by a detritivorous fish, Liza haematocheila T. & S.: effects of temperature, diet and body size

Detritus, as a nutrients reservoir, affects the trophic structure and dynamics of communities and supports a greater diversity of species and longer food chains. Detritivorous fish is an important organism to regenerate the nutrients from sediments. Despite the numerous studies on the nutrients cycle in fish, only a few attempts have been made to quantify the regenerating ability. In the present study, we chose the common detritivorous fish redeye mullet as the research object. Redeye mullet is also a common poly-culture fish in China. Diet, including a commercial diet mostly used in aquaculture and a home-made diet with contents close to detritus, was used and considered as a fixed factor. Temperature was also considered as a fixed factor as much research has shown that temperature has significant effects on fish metabolism. Moreover, body size was regarded as a covariate under analysis of covariance. Three key nutrients, namely carbon, nitrogen and phosphorus, were used to measure the nutrient-regenerating ability of redeye mullet under laboratory conditions. The results showed that the nutrient regeneration in percent of the consumption decreased with increasing temperature. Carbon and nitrogen regeneration of redeye mullet fed on commercial diet was lower than those of the home-made diet group, while the opposite was found for phosphorus. In each group, the amount of regenerated nutrients increased linearly with body size. Fed on the home-made diet, 5-g fish at 25 degrees C can regenerate 210.822 mg C, 37.533 mg N and 0.727 mg P per day.

植食性小型哺乳动物觅食的功能反应模型及其机制检验

采用新鲜苜蓿叶片密集的食物斑块，测定和检验根田鼠觅食苜蓿叶片功能反应模型及其机制。苜蓿叶片大小可调节根田鼠口量，进而控制其瞬时摄入率；根田鼠觅食苜蓿叶片的口量(S)与其瞬时摄入率(I)为渐进函数关系，属II型功能反应，回归方程为I=0.094S/(0.001+S)；根田鼠收获率(B)随其口量(S)的增加呈非线性递减，回归方程为B=0.095/(0.001+S)；最大处理速率的测定值与模型预测值极为近似；瞬时摄入率测定值与预测值之间存在极显著(P < 0.01)的线性回归关系。结果验证了植食性哺乳动物II型功能反应模型能有效地预测其瞬时摄入率动态，收获与咀嚼间的竞争可调节其收获率及瞬时摄入率的假设。

Cloning of hypoxia-inducible factor 1 alpha cDNA from a high hypoxia tolerant mammal - plateau pika (Ochotona curzoniae)

Hypoxia-inducible factor I is a transcription factor composed of HIF-1alpha and HIF-1beta. It plays an important role in the signal transduction of cell response to hypoxia. Plateau pika (Ochotona curzoniae) is a high hypoxia-tolerant and cold adaptation species livin only at 3000-5000m above sea level on the Qinghai-Tibet Plateau. In this study, HIF-1alpha cDNA of plateau pika was cloned and its expression in various tissues was studied. The results indicated that plateau pika HIF-1alpha cDNA was highly identical to those of the human (82%), bovine (89%), mouse (82%), and Norway rat (77%). The deduced amino acid sequence (822 bp) showed 90%, 92%, 86%, and 86% identities with those of the human, bovine, house mouse, and Norway rat, respectively. Northern blot analyses detected two isoforms named pLHIF-1alpha and pSHIF-1alpha. The HIF-1alpha mRNA was highly expressed in the brain and kidney, and much less in the heart, lung, liver, muscle, and spleen, which was quite different from the expression pattern of mouse mRNA. Meanwhile, a new variant of plateau pika HIF-1alpha mRNA was identified by RT-PCR and characterized. The deduced protein, composed of 536 amino acids, lacks a part of the oxygen-dependent degradation domain (ODD), both transactivation domains (TADs), and the nuclear localization signal motif (NLS). Our results suggest that HIF-1alpha may play an important role in the pika's adaptation to hypoxia, especially in brain and kidney, and pika HIF-1alpha function pattern may be different from that of mouse HIF-1alpha. Further-more, for the high ratio of HIF-1alpha homology among the animals, the HIF-1alpha gene may be a good phylogenetic performer in recovering the true phylogenetic relationships among taxa. (C) 2004 Elsevier Inc. All rights reserved.

The abelianization of the Johnson kernel

We prove that the first complex homology of the Johnson subgroup of the Torelli group Tg is a non-trivial, unipotent Tg-module for all g ≥ 4 and give an explicit presentation of it as a Sym H 1(Tg,C)-module when g ≥ 6. We do this by proving that, for a finitely generated group G satisfying an assumption close to formality, the triviality of the restricted characteristic variety implies that the first homology of its Johnson kernel is a nilpotent module over the corresponding Laurent polynomial ring, isomorphic to the infinitesimal Alexander invariant of the associated graded Lie algebra of G. In this setup, we also obtain a precise nilpotence test. © European Mathematical Society 2014.

Neutralizing BAFF/APRIL with atacicept prevents early DSA formation and AMR development in T cell depletion induced nonhuman primate AMR model.

Depletional strategies directed toward achieving tolerance induction in organ transplantation have been associated with an increased incidence and risk of antibody-mediated rejection (AMR) and graft injury. Our clinical data suggest correlation of increased serum B cell activating factor/survival factor (BAFF) with increased risk of antibody-mediated rejection in alemtuzumab treated patients. In the present study, we tested the ability of BAFF blockade (TACI-Ig) in a nonhuman primate AMR model to prevent alloantibody production and prolong allograft survival. Three animals received the AMR inducing regimen (CD3-IT/alefacept/tacrolimus) with TACI-Ig (atacicept), compared to five control animals treated with the AMR inducing regimen only. TACI-Ig treatment lead to decreased levels of DSA in treated animals at 2 and 4 weeks posttransplantation (p < 0.05). In addition, peripheral B cell numbers were significantly lower at 6 weeks posttransplantation. However, it provided only a marginal increase in graft survival (59 ± 22 vs. 102 ± 47 days; p = 0.11). Histological analysis revealed a substantial reduction in findings typically associated with humoral rejection with atacicept treatment. More T cell rejection findings were observed with increased graft T cell infiltration in atacicept treatment, likely secondary to the graft prolongation. We show that BAFF/APRIL blockade using concomitant TACI-Ig treatment reduced the humoral portion of rejection in our depletion-induced preclinical AMR model.

Coupled 3-D finite difference time domain and finite volume methods for solving microwave heating in porous media

Computational results for the microwave heating of a porous material are presented in this paper. Combined finite difference time domain and finite volume methods were used to solve equations that describe the electromagnetic field and heat and mass transfer in porous media. The coupling between the two schemes is through a change in dielectric properties which were assumed to be dependent both on temperature and moisture content. The model was able to reflect the evolution of temperature and moisture fields as the moisture in the porous medium evaporates. Moisture movement results from internal pressure gradients produced by the internal heating and phase change.