高1,2-聚丁二烯及通用橡胶的流变性质

采用多速粘度计和Monsanto试验机联用,在表观剪切速率为3×10~(-8)—2.5×10~8s~(-1)时观察了高1,2-聚丁二烯(PB)生胶与顺式1,4-PB,EPDM,SBR 1500在流变性质上的差异。高1,2-PB虽在中等剪切速率下有较高的粘度,但在低、高剪切速率时的粘度均较低,这一特性有利于它的加工。高1,2-PB在低剪切速率下的流动活化能较其他橡胶高,故抗冷流性能优越,易于存放。

β-环糊精与1,2-苯并蒽络合的荧光研究

通过测量荧光寿命和荧光光谱,研究了1,2-苯并蒽(BA),9,10-二甲基-1,2-苯并蒽(DMBA)与β-环糊精(β-CD)络合过程及荧光猝灭。计算出络合平衡常数和猝灭常数。结果表明,BA与β-CD发生了络合作用,DMBA几乎不与β-CD络合。加入β-CD可使荧光分子的,聚集态与单体间的平衡向生成单体的方向移动,碘离子对BA的猝灭作用也明显减弱。

迟缓爱德华氏菌(Edwardsiella tarda) LuxS/AI-2群体感应系统研究

从患病牙鲆中分离出迟缓爱德华氏菌株TX1，经报告菌株检测发现TX1有AI-2活性。用梯度PCR和Genome walking的方法克隆了TX1 luxS基因，将luxS基因在大肠杆菌DH5α中表达，证明其具有功能活性。在TX1中，luxS的表达与AI-2的活性基本是一致的，二者均受生长时期和生长条件的调节，即在glucose存在的条件下luxS表达和AI-2活性升高，而在高温条件下luxS表达和AI-2活性降低。glucose对AI-2活性以及luxS表达的影响经过荧光定量PCR，启动子活性检测，AI-2活性检测以及凝胶滞缓等一系列的实验证实是由cAMP-CRP复合物介导的，该复合物可以通过与luxS启动子相互作用而抑制luxS的表达。RNA干扰表明，TX1中luxS表达被干扰以后，对细菌产生了多方面的影响，包括：(1) 降低AI-2水平；(2) 降低细菌的生长能力；(3) 降低Ⅲ型分泌系统相关基因的表达水平以及生物膜的形成能力；(4) 减弱细菌毒力。外源AI-2的添加可以回复Ⅲ型分泌系统相关基因的表达水平以及生物膜的形成，但是并不能修复生长状况，表明LuxS在TX1中具有双重功能，即参与细胞代谢以及群体感应信号传导。基于LuxS/AI-2群体感应系统对细菌毒力的重要性，设计并筛选了一个该系统的阻遏因子5411。Pull-down实验证明5411可以和LuxS特异性结合。研究表明5411在TX1中表达导致细菌毒力显著下降。将5411克隆至牙鲆共生菌FP3中，发现5411可以被分泌到胞外并能被TX1吸收。将表达5411的共生菌导入牙鲆，发现其能够有效阻遏TX1对牙鲆的侵染。 这些结果表明：(1) TX1中AI-2的活性受控于LuxS，而后者则受生长时期和生长条件的调控；(2) luxS的正常表达对于细菌的正常生长和侵染是必需的；(3) LuxS/AI-2群体感应系统调控Ⅲ型分泌系统相关毒力因子的表达；(4) 通过阻遏LuxS/AI-2群体感应系统来抑制病原菌侵染是一种具有潜力的新型病害防控方法。

pCO(2) and carbon fluxes across sea-air interface in the Changjiang Estuary and Hangzhou Bay

Partial pressure of CO2 (pCO(2)) was investigated in the Changjiang (Yangtze River) Estuary, Hangzhou Bay and their adjacent areas during a cruise in August 2004, China. The data show that pCO(2) in surface waters of the studied area was higher than that in the atmosphere with only exception of a patch east of Zhoushan Archipelago. The pCO(2) varied from 168 to 2 264 mu atm, which fell in the low range compared with those of other estuaries in the world. The calculated sea-air CO2 fluxes decreased offshore and varied from -10.0 to 88.1 mmol m(-2) d(-1) in average of 24.4 +/- 16.5 mmol m(-2) d(-1). Although the area studied was estimated only 2 x 10(4) km(2), it emitted (5.9 +/- 4.0) x 10(3) tons of carbon to the atmosphere every day. The estuaries and their plumes must be further studied for better understanding the role of coastal seas playing in the global oceanic carbon cycle.

Isolation and characterization of a marine magnetotactic spirillum axenic culture QH-2 from an intertidal zone of the China Sea

Magnetotactic bacteria (MTB) are ubiquitous in aquatic habitats. Because of their fastidious requirements for growth conditions, only very few axenic MTB cultures have been obtained worldwide. In this study, we report a novel marine magnetotactic spirillum axenic culture, designated as QH-2, isolated from the China Sea. It was able to grow in semi-solid or liquid chemically defined medium. The cells were amphitrichously flagellated and contained one single magnetosome chain with an average number of 16 magnetosomes per cell. Phosphate and lipid granules were also observed in the cells. Both rock magnetism and energy-dispersive X-ray spectroscopy characterizations indicated that the magnetosomes in QH-2 were single-domain magnetites (Fe3O4). QH-2 cells swam mostly in a straight line at a velocity of 20-50 mu m/s and occasionally changed to a helical motion. Unlike other magnetotactic spirilla. QH-2 cells responded to light illumination. As a consequence of illumination, the cells changed the direction in which they swam from parallel to the magnetic field to antiparallel. This response appears to be similar to the effect of an increase in [O-2]. Analysis of the QH-2 16S rRNA sequence showed that it had greater than 11% sequence divergence from freshwater magnetotactic spirilla. Thus, the marine QH-2 strain seems to be both phylogenetically and magnetotactically distinct from the freshwater Magnetospirillum spp. studied previously. (C) 2010 Elsevier Masson SAS. All rights reserved.

反式1，4-聚丁二烯的形态和结构研究

高分子材料一般都具有某种特定的结构，这种结构将直接决定着材料的性能。当高聚物从一种结构变为另一种结构时，其材料的性能将发生改变。近来，M.Hikosaka根据聚乙烯结晶的特点，提出了“链滑移扩散理论”，认为对聚合物热处理时，其晶体片层增厚快慢与分子链的滑移扩散能力有关。反式1,4-聚丁二烯(TPBD)在常压下能以六方相稳定存在，是少有的几种具有六方相结构的聚合物。因为其六方相分子链具有较高的构象数，而各个构象之间由于能垒相差不大，构象之间很容易发生转变；因而分子链运动时相对容易，决定了六方相分子链之间的滑移扩散能力较强。为了验证M.Hikosaka的理论，特对样品在六方相温度范围进行热处理。另外由于TPBD在不同的温度下能以两种晶型稳定存在，这两种晶型之间是怎样转变的也是我们关心的问题，而且通过电镜第一次摄得了单斜相和六方相共存的电子衍射。针对上述问题我们进行了下列研究。(1)以三氯化钒体系，稀土催化剂体系合成了两种分子量的反式1,4-聚丁二烯，用IR，NMR分析高分子量样品的反式1,4结构含量为96.2%，低分子量样品反式l,4结构含量为91.2%。对两种分子量样品进行DSC研究，结果表明低分子量样品的转变温度。熔融温度均比高分子量样品低；用Thomoson-Gibbs方程计算了该样品的片层厚度，并与样品的SAXS实验结果对照，认为这种转变温度和熔点的差异除了与1,2-结构的含量有关外，也与不同分子量具有不同的片层厚度有很大关系。(2)对不同分子量的TPBD进行WAXD实验，研究了其在不同温度下的相行为及单斜相向六方相的相转变过程。以PLM为手段跟踪观察了低分子量样品的相态转变，发现许多晶粒在相转变时从视场中消失。用电镜观察到了单斜相电子衍射，六方相电子衍射及单斜相和六方相共存的电子衍射， 并发现两相结构的形貌没有大的差别。(3)用Cerius~2软件模拟了单斜相结构和六方相结构的分子链堆砌，认为单斜相向六方相发生转变时，六方相分子链构象与单斜相分子链构象相比，有序度较低，从而使其堆砌结构变得松散。同时也模拟了单斜相和六方相在晶带轴为[001]方向的电子衍射，实验观察只能得到计算机模拟所得的单斜相和六方相内层的几个电子衍射点。(4)对低分子量样品在64 ℃热处理1小时后进行的DSC，WAXD，SAXS研究表明，样品的片层厚度显著增大，结晶度也相应提高。(5)研究了高分子量样品在85 ℃和低分子量样品在53 ℃热处理不同时间后，所得的DSC曲线。结果表明随时间增加，TPBD的转变峰温度值明显增加；而且发现在前5分钟内处理样品时，结晶度都有明显增加，处理样品5分钟以后结晶度增长缓慢。对高分子量样品四次升降温时，发现降温曲线有肩峰出现，但升温曲线没有肩峰出现，把肩峰的出现归结于有小尺寸亚稳定晶体的形成。(6)对高分子量样品的六方相等温结晶数据及对由熔体快速冷却到一定温度生成单斜相的等温结晶数据进行处理，得到平衡熔点为476K，比文献值高。并利用Thomoson-Gibbs方程，得到了单斜相和六方相的温度对尺寸倒数的相图，确定了在一定尺寸下单斜相和六方相稳定存在的温度范围。(7)用电镜观察了在70 ℃热处理不同时间后所得形貌图，并讨论了样品在六方相中热处理时，样品聚集体的聚集方式。(8)研究了两种分子量样品溶液结晶时所得的球晶形貌，发现其结晶形貌与分子量有关，而且发现摄得的电子衍射是六方相电子衍射，而不是室温下稳定存在的单斜相电子衍射，认为是由于电子辐照使样品升温而发生了晶型转变。(9)用修饰后的Avrami方程，Ozawa，方程分别处理了TPBD非等温结晶数据，由Jeziorny修饰的Avrami方程分析显示TPBD的非等温结晶明显地分为一次结晶和二次结晶两个阶段，指数值n意味着一次结晶和二次结晶的成核种类，Ozawa方程分析不能很好地适用于TPBD的六方相非等温结晶数据，主要是由于Ozawa理论的不精确假定，如二次结晶，结晶温度对片层厚度相关性及整个结晶过程中恒定的冷却函数等。并由Kissinger方程得到六方相的结晶活化能为167.9kJ/mol。

4,4',4",4"'-四羧基酞菁钴（II）高分子载体化及其催化硫醇的氧化反应

高分子催化剂的研究是高分子化学的重要课题之一。将金属酞菁高分子化，除有一般催化剂高分子化的特点之外，还有将催化活性中心用高分子骨架分隔开，以防生成催化活性低的二聚体，从而提高有效活性中心浓度的特殊意义。本论文研究了将4,4',4",4"'-四羧基酞菁钴（II）固载在接枝有高分子碱的二氧化硅上，合成双功能高分子催化剂。并结合2-羟基乙硫醇的氧化探索了其催化活性。以气相法4号白炭黑为载体，利用γ-氨丙基三乙氧基硅烷的水解反应，在白炭黑表面包裹聚γ-氨丙基硅氧烷。然后在DCCI脱水剂存在下，使CoPc(COOH)_4连接上述高分子载体上。通过红外光谱分析，表明产物中有酰胺键，证明是通过共价键连接，但亦不能排除有部分是以配位键结合的。用液相共辐照方法在硅胶H上接枝聚苯乙烯，对所得产物进行了表征，根据接枝的聚苯乙烯的重均分子量大于未接枝的聚苯乙烯，认为在液相单体中共辐照，其反应机理有可能与文献上研究硅胶与苯乙烯气相共辐照或预辐照接枝共聚的机理相似。在其它条件固定时，接枝率随着辐照时间的增加而增大。将接枝在硅胶H表面的聚苯乙烯进行氨甲基化，制得高分子碱载体。其结构通过元素分析和红外光谱证明与预想的相符。另外，用液相共辐照方法，在硅胶H上接枝苯乙烯与2-（或4-）乙烯基吡啶的共聚物，而文献上制取相同的载体是用化学方法进行的。与化学方法相比，辐照法有接枝率高，方法简便的优点。实验中观察到，在单体配比相同时，接枝率随剂量增加而增加，但到达最大值后又开始下降。同时，在剂量一定的情况下，随着单体中2-乙烯基吡啶含量的增加，接枝率下降接枝共聚物中聚比（2-乙烯基吡啶/苯乙烯）也比投料比低。对上述现象进行了初步解释，根据在γ-射线辐照时，2-乙烯吡啶比苯乙烯易于引发聚合，则随着单体中2-乙烯基吡啶含量的增加，未接枝聚合反应消耗了很多2-乙烯基吡啶单体，这样用于接枝聚合的单体量减少，造成接枝率下降，以及接枝共聚物中（2-乙烯基吡啶/苯乙烯）共聚比低于投料比的情况。用裂解色谱对未接枝的苯乙烯与2-乙烯基吡啶共聚物进行了表征，实验结果表明，共聚物中2-乙烯基吡啶的百分含量与裂解产物中2-乙烯基吡啶的百分含量之间有很好的线性关系，可以用来分析苯乙烯与2-乙烯基吡啶共聚物的组成。将CoPc(COOH)_4以共价或吸附形式接到上述高分子载体上分别合成出相应的含CoPc(CHHO)_4的高分子催化剂，其中对共价键结合的产物，用原子吸收光谱法定出了轱含量。结合2-羟基乙硫醇氧化反应，初步研究催化剂活性。所合成的高分子催化剂一般在少碱甚至无碱的情况下均有一定的催化活性。当反应在水溶液中进行，CoPc(COOH)_4负载在硅胶H上接枝的聚苯乙烯氨甲基化产物上，其催化活性优于含有吡啶基团的高分子载体。当反应在聚2-乙烯基吡啶的良溶剂，聚苯乙烯的劣溶剂乙醇中进行时，表面接枝不同共聚比苯乙烯与2-乙烯基吡啶的硅胶H为催化剂载体，其催化活性随着苯乙烯含量增加而下降。初步认为是苯乙烯含量增加，表面共聚物在乙醇中溶解性变差，空间阻碍增加，吸附CoPc(COOH)_4的能力及底物向活性中心扩散困难所致。影响固载在接枝共聚物上的金属酞菁催化剂，催化活性的因素很多。通过本工作初步认为含有碱性强的碱性基团和溶解性好的交链可能是合成具有理想催化活性剂的先决条件。关于所合成的高分子催化剂的催化活性尚有待于进一步的工作。

红松和长白松针叶暗呼吸对连续4个生长季高浓度CO_2处理的响应

以开顶箱法研究了高浓度CO2对长白山两种针叶树—红松和长白松针叶暗呼吸作用的长期影响.对两个树种连续4个生长季进行700和500μmol·mol-1CO2处理,同时设接受大气CO2浓度(约350μmol·mol-1CO2)的开顶箱为对照,在CO2处理的第2,3和4个生长季分别测定了针叶的暗呼吸速率.结果表明:CO2处理的第2个生长季,高浓度CO2下红松和长白松针叶暗呼吸速率增加,可能与碳氮含量变化有关;CO2处理的第3个生长季,高浓度CO2条件下生长的红松针叶暗呼吸速率增加,长白松针叶的暗呼吸速率下降,两树种呈不同响应主要与植株的生长速率不同有关;CO2处理的第4个生长季,红松和长白松针叶的暗呼吸速率均受高浓度CO2抑制.第3个生长季通过改变测量CO2浓度,发现高浓度CO2对长白松针叶暗呼吸作用的短期效应与长期效应呈现一致性,红松不完全相同.红松和长白松针叶的暗呼吸作用对高浓度CO2的响应与CO2处理时间及植株个体的生长发育阶段有关,暗呼吸速率的变化是CO2直接作用与长期驯化共同作用的结果,不能用短期的测定结果预测针叶暗呼吸对高浓度CO2响应的长期效应.

Thiophene-NPN Ligand Supported Rare-Earth Metal Bis(alkyl) Complexes. Synthesis and Catalysis toward Highly trans-1,4 Selective Polymerization of Butadiene

A series of new rare-earth metal bis(alkyl) complexes [L(1-3)Ln(CH2SiMe3)(2)(THF)(n)] (L-1 = MeC4H2SCH2NC6H4(Ph)(2)P=NC6H2Me3-2,4,6: Ln = Sc, n = 1 (1a); Ln = Lu, n = 1 (1b); L-2 = MeC4H2SCH2NC6H4(Ph)(2)P=NC6H3Et2-2,6: Ln = Sc, n = 1 (2a); Ln = Lu, n = 1 (2b); Ln = Y, n = 1 (2c); L-3 = MeC4H2SCH2NC6H4(Ph)(2)P=(NC6H3Pr2)-Pr-i-2,6: Ln = Sc, n = 0 (3a)) and (LSc)-Sc-4(CH2SiMe3)(2()THF) (4a) (L-4 = C6H5CH2NC6H4(Ph)(2)P=NC6H3Et2-2,6) have been prepared by reaction of rare-earth metal tris(alkyl)s with the corresponding HL1-4 ligands via alkane elimination.

铁系3,4-聚异戊二烯橡胶的性能

考察了以异辛酸铁、三异丁基铝和偶氮二异丁腈催化剂在己烷中50℃下制备的3,4-聚异戊二烯(3,4-IR)[3,4(+1,2)结构质量分数约为50%,ML110+04℃为52,玻璃化转变温度为-21.6℃]与SBR或NR质量比为20/80组成的共混胶的力学性能和粘弹性能。SBR/3,4-IR和NR/3,4-IR共混胶与SBR或NR相比,其拉伸强度和扯断伸长率有所下降,回弹性明显降低,但硬度基本不变。根据0℃和60℃下的损耗因子tanδ值可知,3,4-IR可明显提高SBR或NR硫化胶的抗湿滑性能,并使滚动阻力有所降低。

Water resistant sulfonated polyimides based on 4,4'-binaphthyl-1,1',8,8'-tetracarboxylic dianhydride (BNTDA) for proton exchange membranes

A series of sulfonated polyimides (SPIs) were synthesized in in-cresol from 4,4'-binaphthyl- 1,11,8,8'-tetracarboxylic dianhydride (BNTDA), 4.4'-diaminodiphenylether-2,2-disulfonicacid (ODADS), and 4.4'-diamino-diphenyl ether (ODA) in the presence of triethylamine and benzoic acid. The resulted polyimides showed much better water resistance than the corresponding sulfonated polyimides from 1,4,5,8-naphthatenetetracarboxylic dianhydride (NTDA) and ODADS, which is contributed to the higher electron density in the carbonyl carbon atoms of BNTDA. Copolyimides S-75 and S-50 maintained their mechanical properties and proton conductivities after aging in water at 100 degrees C for 800 h. The proton conductivity of these SPIs was 0.0250-0.3565 S/cm at 20 degrees C and 100% relative humidity (RH), and increased to 0.11490.9470 S/cm at 80 degrees C and 100% RH. The methanol permeability values of these SPIs were in the range of 0.99-2.36 x 10(-7) cm(2)/S, which are much lower than that of Nafion 117 (2 x 10(-6) cm(2)/s).

Preparation and properties of microporous membrane from poly(vinylidene fluoride-co-tetrafluoroethylene) (F2.4) for membrane distillation

Flat-sheet microporous membranes from F2.4 for membrane distillation (MD) were prepared by phase inversion process. Dimethylacetamide (DMAC) and LiClO(4)(.)3H(2)O/trimethyl phosphate (TMP) were, respectively, used as solvent and pore-forming additives. The effects of casting solution composition, exposure time prior to coagulation and temperature of precipitation bath on F2.4 membrane structure were investigated. The morphology of resultant porous membrane was observed by scanning electron microcopy. Some natures of F2.4 porous membrane after drying in air, such as mechanical properties and hydrophobicity, were exhibited and compared with poly(vinylidene fluoride) (PVDF) membrane prepared by the same ways. Stress-at-break and strength stress of F2.4 microporous membrane are higher than that of PVDF membrane, and elongation percentage of F2.4 membrane at break is about eight-fold as great as that of PVDF membrane. Contact angle of F2.4 microporous membrane to water (86.6 +/- 0.51degrees) was also larger than that of PVDF mernbrane (80.0 +/- 0.78degrees). MD experiment was carried out using a direct contact membrane distillation (DCMD) configuration as final test to permeate performance of resultant microporous membrane.

Synthesis and properties of soluble polyimides based on isomeric ditrifluoromethyl substituted 1,4-bis(4-aminophenoxy)benzene

A new fluorinated diamine monomer, [1,4-bis(4-amino-3-trifluoromethylphenoxy)benzene (2)], and a known isomeric analog 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (3) were synthesized. A series of organosoluble polyimides Ia-d and IIa were prepared from the diamines (2, 3) and dianhydrides (a-d) by a high-temperature one-step method. The effects of the trifluoromethyl substituents on the properties of polyimides were evaluated through the study of their soluble, thermal, optical, and gas permeability properties. Polyimides (Ia-d) had glass transition temperatures between 229 and 279 degrees C, and the temperatures at 5% weight loss ranged from 510 to 533 degrees C under nitrogen. These polyimides could be cast into flexible and tough membranes from DMAc solutions. The membranes had tensile strengths in the range of 137-169 MPa, tensile modulus in the range of 1.6-2.2 GPa and elongations at break from 11% to 14%. The polyimide la with trifluoromethyl groups ortho to the imide nitrogen exhibited enhanced gas permeability, solubility, transparency, and thermal stability compared with the isomeric polyimide IIa with the CF3 group meta to the imide nitrogen.

Novel sodium sulfonate-functionalized poly(ether ether ketone)s derived from 4,4 '-thiodiphenol

Novel sodium sulfonate-functionalized poly(ether ether ketone)s derived from 4,4'-thiodiphenol with degree of sulfonation up to 2.0 were synthesized by nucleophilic polycondensation of various amount of 5,5 '-carbonylbis(2-fluorobenzenesulfonate) (1) and 4,4'-difluorobenzophenone (2) with 4,4'-thiodipheno (3). Component and structure of the polymers were confirmed by TR, NMR and elemental analysis. Wide angle X-ray diffraction patterns indicated an amorphous structure of the polymers. All the polymers showed excellent thermal stability and poor solubility in water. (C) 2001 Elsevier Science Ltd. All rights reserved.