Effect of irradiation on pyrolysis of polypropylene in the presence of zeolites

For recycling of waste polymers, the degradation behavior of PP was studied with a combination of radiolysis and thermolysis methods. The results revealed that thermal degradation temperature of PP was significantly reduced when PP was irradiated in the presence of a zeolite. The irradiation-induced temperature reduction depended on the zeolite structure and composition, as well as on the morphology of the mixture. Identification of pyrolysis products indicated that, in the absence of zeolite, irradiation resulted only in a change of the product distribution but no formation of new compounds. In the presence of zeolite, however, a series of oxidized products were formed. In addition, the pyrolysis could be performed at a much lower temperature. (C) 1996 Elsevier Science Limited

辐射法研制功能高分子膜离子选择电极活性材料

用辐射接枝工艺合成了功能高分子膜活性材料,并对其进行了表征,测定了以此为活性材料的离子选择电极性能。结果发现,硫酸根电极在10~(-1)—10~(-3)mol/L Na_2SO_4溶液中响应时间<70s,斜率为52mV/PSO_4~(2-);氯离子电极的线性范围1×10~(-1)—2×10~(-4)mol/L,检测下限为8×10~(-5)mol/L,稳定性好,寿命长,响应时间<5s,内阻<60kΩ,抗毒化能力强。从稀土离子选择电极中发现,以辐射接枝工艺合成的材料比化学法合成的好,前者斜率为53 mV/PGd,后者斜率为46 mV/PGd;预辐照接枝工艺合成的材料比共辐照接枝工艺的好些。

针叶树越冬针叶光氧化与叶绿体超氧阴离子自由基

以Tiron为自旋探针,检出了越冬针叶叶绿体指示超氧阴离子自由基产生的TH~·ESR信号。此信号可由紫外辐射,也可由光合有效辐射产生。以单位叶绿素量为基数计算的信号强度比已报道的其它植物材料大2～3个数量级。红松叶绿体信号又大于其它针叶树。此信号可被外源SOD,抗坏血酸、乙醇和N_2抑制;随光照增加而增强,12月到次年5月期间又随时间而增强。上述结果表明红松针叶的冬季光氧化伤害与叶绿体中过量超氧阴离子自由基的产生有关。

(η~5-C_5H_5)_2Yb(THF)_2的新合成方法及其晶体结构

双(环戊二烯基)镱(Ⅱ)四氢呋喃配合物(η~5-C_5H_5)_2Yb(THF)_2通过环辛二烯基钾(KC_8H_(11))还原(C_5H_5)_2YbCl·THF而得到,经元素分析、红外光谱表征,并测定了其晶体结构。配合物属单斜晶系,C2/c空间群,晶体学参数a=1.3564(4),b=0.9569(3),c=1.4747(6)nm;β=109.90(3)°;V=1.79975(118)nm~3;D_c=1.65·cm~(-3);μ_C=54.7cm~(-1)(Mo);F(000)=880,Z=4。最后一致性因子R=0.079,R_w=0.081。Yb~(2+)的配位数为8。

聚合物共混体系辐射交联反应中溶胶分数与辐照剂量间的关系

我们已建立了线性聚合物辐射交联反应中溶胶分数(S)与辐照剂量(R)间的关系式:R(S+S~(1/2))=1/q_0u_1+α_0R~β/q_0,(1)式中β是与高分子结构有关的参数β=2×10~(-3)T-g+0.206。(2)

亲水膜的表面改性及在膜蒸馏中的应用

膜的微孔性和疏水性是水溶液膜蒸馏的两个基本条件,迄今人们均采用疏水性高分子材料制成疏水微孔膜用于膜蒸馏研究。本文采用辐照接枝聚合和等离子体表面聚合的方法,将亲水的醋酸纤维素微孔膜和硝酸纤维素微孔膜表面疏水化改性,成功地用于膜蒸馏研究,大大扩展了疏水微孔膜的材料来源。实验结果表明,亲水膜表面改性得到的疏水膜,其膜蒸馏性能不低于疏水材料制成的膜,尤其是等离子体聚合法可以实现多种特殊单体在多孔的材料表面聚合,成为制备高性能疏水微孔膜的有效手段,为膜蒸馏的深入发展和实用化创造了有利条件。

SmP_5O_(14)晶体中Sm~(3+)离子的能级和晶场参数

本文利用光谱方法测定了SmP_5O_(14)晶体中Sm~(3+)离子的能级,通过拟合定出晶场参数,利用这些参数所计算的能级和实验能级符合得很好。

Differences in the rDNA-bearing chromosome divide the Asian-Pacific and Atlantic species of Crassostrea (Bivalvia, Mollusca)

Karyotype and chromosomal location of the major ribosomal RNA genes (rDNA) were studied using fluorescence in situ hybridization (FISH) in five species of Crassostrea: three Asian-Pacific species (C. gigas, C. plicatula, and C. ariakensis) and two Atlantic species (C. virginica and C. rhizophorae). FISH probes were made by PCR amplification of the intergenic transcribed spacer between the 18S and 5.8S rRNA genes, and labeled with digoxigenin-11-dUTP. All five species had a haploid number of 10 chromosomes. The Atlantic species had 1-2 submetacentric chromosomes, while the three Pacific species had none. FISH with metaphase chromosomes detected a single telomeric locus for rDNA in all five species without any variation. In all three Pacific species, rDNA was located on the long arm of Chromosome 10 (10q)-the smallest chromosome. In the two Atlantic species, rDNA was located on the short arm of Chromosome 2 (2p)-the second longest chromosome. A review of other studies reveals the same distribution of NOR sites (putative rDNA loci) in three other species: on 10q in C. sikamea and C. angulata from the Pacific Ocean and on 2p in C. gasar from the western Atlantic. All data support the conclusion that differences in size and shape of the rDNA-bearing chromosome represent a major divide between Asian-Pacific and Atlantic species of Crassostrea. This finding suggests that chromosomal divergence can occur under seemingly conserved karyotypes and may play a role in reproductive isolation and speciation.

Topographic changes in nascent and early mesoderm in amphioxus embryos studied by Dil labeling and by in situ hybridization for a Brachyury gene

In amphioxus embryos, the nascent and early mesoderm (including chorda-mesoderm) was visualized by expression of a Brachyury gene (AmBra-2). A band of mesoderm is first detected encircling the earliest (vegetal plate stage) gastrula sub-equatorially. Soon thereafter, the vegetal plate invaginates. resulting in a cap-shaped gastrula with the mesoderm localized at the blastoporal lip and completely encircling the blastopore. As the gastrula stage progresses, DiI (a vital dye) labeling demonstrates that the entire mesoderm is internalized by a slight involution of the epiblast into the hypoblast all around the perimeter of the blastopore. Subsequently. during the early neurula stage, the internalized mesoderm undergoes anterior extension mid-dorsally (as notochord) and dorsolaterally (in paraxial regions when segments will later form). By the late neurula stage, AmBra-2 is no longer transcribed throughout the mesoderm as a whole; instead. expression is detectable only in the posterior mesoderm and in the notochord, but not in par axial mesoderm where definitive somites have formed.

Cloning and characterization of a novel C-type lectin from Zhikong scallop Chlamys farreri

C-type lectin is a family of Ca2+ dependent carbohydrate-recognition proteins which play crucial roles in the innate immunity of invertebrates by mediating the recognition of host cells to pathogens and clearing microinvaders as a pattern recognition protein (PRP). The cDNA of Zhikong scallop Chlamys farreri C-type lectin (designated CFLec-1) was cloned by expressed sequence tag (EST) and RACE techniques. The full-length cDNA of CFLec-1 was 1785 bp, consisting of a 5'-terminal untranslated region (UTR) of 66 bp and an unusually long 3' UTR of 1040 bp with seven polyadenylation signal sequences AATAAA and a poly(A) tail. The CFLec-1 cDNA encoded a polypeptide of 221 amino acids with a putative signal peptide of 15 amino acid residues and a mature protein of 206 amino acids. Analysis of the protein domain features indicated a typical long-form carbohydrate-recognition domain (CRD) of 130 residues in the CFLec-1 deduced amino acid sequence. The expression pattern of CFLec-1 transcripts in healthy and bacterial challenged scallops was studied by semi-quantitative RT-PCR. mRNA transcripts of CFLec-1 could be mainly detected in the tissues of haemocytes, gill, gonad and mantle of unchallenged scallops, whereas the expression of CFLec-1 transcripts was increased in all the tested tissues after heat-killed Vibrio anguillarum challenge. The temporal expression of CFLec-1 mRNA in haemolymph challenged by Micrococcus luteus and V anguillarum was both up-regulated and reached the maximum level at 8 and 16 It post stimulation, respectively, and then dropped back to the original level. In order to investigate its immune functions, CFLec- I was recombined and expressed in Escherichia coli BL21(DE3)-pLysS as a fusion protein with thioredoxin. The recombinant CFLec-1 agglutinated bacteria E. coli JM109 in vitro, and the agglutination was Ca2+ dependent which could be inhibited by EDTA. But it did not agglutinate M. luteus, Candida lipolytica and animal erythrocytes including rabbit, rat, mouse, chicken, human group A, human group B, human group O. Meanwhile, the recombinant CFLec-1 could inhibit the growth of both E. coli JM 109 and M. luteus, but no inhibition activity against V anguillarum. These result indicated that CFLec-1 was a constitutive and inducible PRP which was involved in the reorganization and clearance of invaders in scallop. (c) 2006 Elsevier Ltd. All rights reserved.

珠江口冲淡水扩展变化及机制研究

本文利用1978~1984年南海北部的逐月调查资料，分析珠江口冲淡水的扩展特征及其扩展变化。资料分析显示，在风及入海径流量等因素的影响下，珠江口冲淡水的扩展具有季节变化和年际变化。夏季珠江口冲淡水在河口外的扩展形态可划分出四种扩展形态，包括向海扩展型、粤东扩展型、粤西扩展型及似对称扩展型。同时根据珠江入海月平均流量与冲淡水扩展面积的相关分析可知，珠江口入海流量的大小决定了河口冲淡水在口外的扩展大小，流量的季节变化决定了冲淡水扩展大小的季节变化，而流量的年变化影响着冲淡水扩展的年变化。根据海域风场与冲淡水扩展形态的对比分析表明，风的季节变化和日变化影响着冲淡水扩展方向的变化，风场影响控制了珠江口冲淡水不同的扩展形态。夏季在E~SE向风的作用下，珠江口冲淡水扩展表现为粤西扩展型；而珠江口冲淡水扩展为粤东扩展型时，南海北部的月平均风场为SSW~SW向风。冲淡水扩展倾向于向海扩展型时，海域吹S风为主，且风速较小。 在资料分析的基础上，本文利用ECOM模式对冲淡水扩展的动力机制进行进一步探讨。模式试验结果表明，理想情况下，珠江河口冲淡水向外海突出，冲淡水扩展形态为向海扩展型；珠江入海流量的大小决定冲淡水扩展范围的大小，入海流量大，冲淡水扩展的范围大。不同方向的盛行风是珠江河口冲淡水扩展形态和动力的决定因子。在东北风、东风和东南风的作用下，河口冲淡水形态为粤西扩展型，风持续时间长，冲淡水扩展形态表现为极端粤西扩展型。在西南季风的影响下，河口冲淡水的扩展方向明显相反，冲淡水扩展形态表现为典型的粤东向离岸扩展型。S、SSE风约束了河口冲淡水向口外的扩展，冲淡水扩展形态表现为轻微的粤东向扩展。在偏E风与偏S风交替作用下，表层冲淡水在一定时刻会出现似对称形态。 在对南海北部潮汐潮流研究的基础上，本文进一步模拟了潮汐潮流对珠江口冲淡水扩展的影响。模型试验结果显示，珠江口周期性的潮流运动所造成的低盐水的净水平输运很小，其主要作用更多体现在对冲淡水与周围高盐水体的混合上，在很大程度上限制了低盐水向海或向两侧方向的扩展。 在模型试验的基础上，本文进一步模拟了在多种动力因子作用下夏季珠江口冲淡水的扩展演化规律。模式计算表明，珠江口冲淡水扩展形态的演变受多种因素影响，而风是其中影响冲淡水扩展演化最重要的因子。 将考虑斜压效应和不考虑斜压效应的模式计算结果进行比较，结果显示珠江口冲淡水扩展对粤东、粤西沿岸流的形成和发育影响明显。夏季珠江口冲淡水的扩展可促进粤东沿岸流的进一步发育，粤东沿岸流强化。而影响粤西沿岸流的主要因子是风应力和珠江口冲淡水的西向扩展，无风或弱风时，粤西西向流主要是由于冲淡水与周围水体的压力差所产生的密度流经过地转调整作用形成的；否则是SE~NE风与珠江口冲淡水的西向扩展同时影响粤西沿岸流的西向流动。

Formation of Fe-oxyhydroxides from the East Pacific Rise near latitude 13 degrees N: Evidence from mineralogical and geochemical data

The mineralogical and geochemical characteristics of Fe-oxyhydroxide samples from one dredge station (long. 103 degrees 54.48'W, lat. 12 degrees 42.30'N, water depth 2655 m) on the East Pacific Rise near lat 13 degrees N were analyzed by XRD, ICP-AES, and ICP-MS. Most Fe-oxyhydroxides are amorphous, with a few sphalerite microlites. In comparison with Fe-oxyhydroxides from other fields, the variable ranges in the chemical composition of Fe-oxyhydroxide samples are very narrow; their Fe, Si, and Mn contents were 39.90%, 8.92%, and 1.59%, respectively; they have high Cu (0.88%-1.85%) and Co (65x10(-6)-704x10(-6)) contents, and contain Co+Cu+Zn+Ni > 1.01%. The trace-element (As, Co, Ni, Cu, Zn, Ba, Sr) and major-element (Fe, Ca, Al, Mg) contents of these samples are in the range of hydrothermal sulfide from the East Pacific Rise near 13 degrees N, reflecting that this type of Fe-oxyhydroxide constitutes a secondary oxidation product of hydrothermal sulfide. The Fe-oxyhydroxide samples from one dredge station on the East Pacific Rise near 13 degrees N are lower in Sigma REE (5.44x10(-6)-17.01x10(-6)), with a distinct negative Ce anomaly (0.12-0.28). The Fe-oxyhydroxide samples have similar chondrite-normalized rare-earth-element (REE) patterns to that of seawater, and they are very different from the REE composition characteristics of hydrothermal plume particles and hydrothermal fluids, showing that the REEs of Fe-oxyhydroxide are a major constituent of seawater and that the Fe-oxyhydroxides can become a sink of REE from seawater. The quick settling of hydrothermal plume particles resulted in the lower REE content and higher Mn content of these Fe-oxyhydroxides, which are captured in part of the V and P from seawater by adsorption. The Fe-oxyhydroxides from one dredge station on the East Pacific Rise near 13 degrees N were formed by secondary oxidation in a low temperature, oxygenated environment. In comparison with the elemental (Zn, Cd, Pb, Fe, Co, Cu) average content of hydrothermal sulfide samples from the East Pacific Rise near 13 degrees N, the Zn, Cd, and Pb contents of the Fe-oxyhydroxides are lower, and their Fe, Co, and Cu contents are higher.

栉孔扇贝凝集素家族基因研究

栉孔扇贝是我国北方重要的贝类养殖品种。自1997年以来爆发的栉孔扇贝大规模死亡，给地区经济造成了重大损失并且已经严重威胁扇贝养殖业的健康发展。然而，到目前为止，对扇贝免疫防御的分子机理了解还很少，深入研究扇贝免疫应答的分子机制是认识和了解病害发生和实现病害控制的关键问题之一。本研究采用了EST大规模测序结合cDNA锚定扩增的方法，从栉孔扇贝cDNA文库中克隆到五个C－型凝集素基因，并对其中部分基因进行了深入研究。 C－型凝集素CFLec－1的基因全长1785bp，其中含有5’非翻译区66bp，随后是666bp的开放阅读框；最后一条非常长的3’非翻译区1040bp，其中包含多个多聚腺甘酸加尾信号和polyA尾巴。栉孔扇贝CFLec－1编码221个氨基酸的蛋白，其N末端为15个氨基酸的信号肽。CFLec－1的成熟肽为206个氨基酸，其等电点为5.12，计算分子量为23.49kDa。SMART程序分析显示，C末端130氨基酸是一个标准的长型C－型凝集素结构域，其中四个半光胺酸（Cys104，Cys177，Cys193，Cys202）形成的两对二硫键维持了C－型凝集素的空间结构，而位于N末端的两个二硫键（Cys74，Cys85）构成了长型C－型凝集素结构域特有的一对额外二硫键。同源性分析表明，CFLec－1的C－型凝集素结构域与红原鸡的甘露糖受体中的C－型凝集素结构域有47％的相似度，与大西洋鲑的C－型凝集素受体C有31％的相似度。通过与其他同源的C－型凝集素结构域序列比对，发现了可能的糖结合位点EPD基域（Glu169-Pro170-Asp171）。通过RT－PCR研究CFLec－1在扇贝不同组织中的分布后发现，在健康扇贝中，CFLec－1在性腺中有中等程度的表达，在腮中有少量表达，在血淋巴和外套膜中有微量表达。经热处死的鳗弧菌刺激后，CFLec－1在几乎所有检测组织中的表达量都有明显的提高，其中，血淋巴中的表达量变化最为显著。这些结果说明CFLec－1是组成/诱导型基因，并且可能参与了黏膜防御。通过RT－PCR分析了CFLec－1在血淋巴中的表达特征后发现，在革兰氏阳性菌溶壁微球菌和革兰氏阴性菌鳗弧菌刺激后，CFLec－1的表达均显著高于对照组，并且成明显的随时间变化趋势。在大肠杆菌中表达的重组CFLec－1可以凝集革兰氏阴性菌大肠杆菌JM109，且凝集过程需要钙离子的参与。重组CFLec－1对大肠杆菌JM109有较弱的抑菌活性，对溶壁微球菌有明显的抑菌活性，对鳗弧菌没有抑菌活性。这一结果说明，CFLec－1可能不仅参与对入侵微生物的识别过程，而且可能作为效应分子起到了直接杀灭入侵微生物的作用。 CFLec-2的cDNA全长为708bp，其5’UTR为59bp。3’UTR为217bp。 CFLec-2的开放阅读框为432bp，编码160个氨基酸残基,其中包含5’信号肽17个残基。CFLec-2的编码区中含有一个C-型凝集素结构域。利用本研究中构建的原核表达载体，CFLec-2的成熟肽在大肠杆菌中被成功表达。 mCFLec-1的cDNA全长为2257bp，5’UTR17bp，3’UTR为713bp。mCFLec-1的开放阅读框为1527bp，编码508个氨基酸残基，其中包含17个氨基酸残基的信号肽序列。mCFLec-1的编码区含有三个串联的C-型凝集素结构域。利用本研究中构建的原核表达载体，mCFLec-2的成熟肽在大肠杆菌中被成功表达。 mCFLec-2的cDNA全长2086bp。其5’UTR长为18bp，3’UTR长为238bp。开放阅读框均为1776bp，编码609个氨基酸残基，其中包含N末端由18个氨基酸构成的信号肽。mCFLec-2的编码区包含四个C-型凝集素结构域。mCFlec-3的cDNA全长1897bp，其5’UTR和编码区与mCFLec-2几乎完全相同，只有个别碱基的差异。mCFlec-3的3’UTR为49bp。 本研究从扇贝机体本身的免疫机制入手，深入探讨其免疫机理，为进一步研究信号传导，了解扇贝先天性免疫的机制，为制定合理的研制策略提供坚实的理论基础；丰富和发展海水无脊椎动物免疫学的内容，为控制养殖生物疾病提供了新的思路；进一步通过高低等生物之间功能类似分子的同源性比对，为解释和阐明先天免疫这种已经存在数十亿年，从低等生物开始到人类仍旧保留且更加完善的免疫系统的奥秘和本质提供证据。