YBa_2Cu_3O_(7-Y)超导体激光熔凝处理的研究

利用CO_2激光对YBa_2Cu_3O_(7-Y)块材进行熔凝处理后,证明可逆反应式YBa_2Cu_3O_(7-Y)(?)Y_2Cu_2O_5+4BaCuO_2成立,在结构上消除了孔洞等缺陷,使晶粒细化均匀,有序化程度及致密度提高,有效地提高了材料的临界电流密度J_c,从而提出用CO_2激光制备高温超导体YBa_2Cu_3O_(7-y)超导体块材、带材及线材实用化的新工艺.

稀土-其它过渡金属混合催化剂用于共轭双烯烃的聚合——Ⅲ.关于两种活性中心及其聚合机理的探讨

研究了(NdCl_3+FeCl_3)r phen-HA_2(i-Bu)_2体系聚合丁二烯。通过固定催化剂中稀土(或铁)含量而改变铁(或稀土)含量的方法,证明了此聚合体系中存在两种不同的对丁二烯聚合有很高催化活性的活性中心,即能使丁二烯聚合成高顺式产物的Nd活性中心,和使丁二烯聚合成几乎是等二元(cis-1,4和1,2构型),聚合物的Fe活性中心。所得产物具确两个T_g和产物分级后可得到cis-1,4为92％和1,2含量为54％的级分,为以上结论也提供了旁证。两种活性中心的催化活性受铝比、聚合温度等的影响,稀土活性体对聚合条件比过渡金属活性体有较宽的适应范围。对其聚合机理进行了探讨,认为两种活性中心分别按各自的聚合机理进行聚合反应。

高压离子交换柱柱效初探及镧系元素的快速制备分离

本文探讨了操作条件与高压离子交换柱柱效的关系,研究了洗脱液梯度以及交换柱直径与树脂床高度比例对镧系元素分离的影响。在选定的最佳分离条件下,用自制高压离子交换色谱仪和国产阳离子交换树脂实现了除钷以外的所有镧系元素的快速分离,相邻元素之间皆达到了基线分离。

A clip domain serine protease (cSP) from the Chinese mitten crab Eriocheir sinensis: cDNA characterization and mRNA expression

Clip domain serine protease (cSP), characterized by conserved clip domains, is a new serine protease family identified mainly in arthropod, and plays important roles in development and immunity. In the present study, the full-length cDNA of a cSP (designated EscSP) was cloned from Chinese mitten crab Eriocheir sinensis by expressed sequence tags (ESTs) and PCR techniques. The 1380 bp EscSP cDNA contained a 1152 bp open reading frame (ORF) encoding a putative cSP of 383 amino acids, a 5'-untranslated region (UTR) of 54 bp, and a 3'-UTR of 174 bp. Multiple sequence alignment presented twelve conserved cysteine residues and a canonical catalytic triad (His(185), Asp(235) and Ser(332)) critical for the fundamental structure and function of EscSP. Two types of cSP domains, the clip domain and tryp_spc domain, were identified in the deduced amino acids sequence of EscSP. The conservation characteristics and similarities with previously known cSPs indicated that EscSP was a member of the large cSP family. The mRNA expression of EscSP in different tissues and the temporal expression in haemocytes challenged by Listonella anguillarum were measured by real-time RT-PCR. EscSP mRNA transcripts could be detected in all examined tissues, and were higher expressed in muscle than that in hepatopancreas. gill, gonad, haemocytes and heart. The EscSP mRNA expression in haemocytes was up-regulated after L anguillarum challenge and peaked at 2 h (4.96 fold, P < 0.05) and 12 h (9.90 fold, P < 0.05). Its expression pattern was similar to prophenoloxidase (EsproPO), one of the components of crab proPO system found in our previous report. These results implied that EscSP was involved in the processes of host-pathogen interaction probably as one of the proPO system members. (C) 2009 Elsevier Ltd. All rights reserved.

First molluscan TNFR homologue in Zhikong scallop: Molecular characterization and expression analysis

Tumor necrosis factor receptors (TNFRs) are a superfamily of proteins characterized by the unique cysteine-rich domain (CRD) and their important roles in diverse physiological and pathological events such as inflammation, apoptosis, autoimmunity and organogenesis. The first member of the molluscan TNFR family, designated as CfTNFR, was identified from Zhikong scallop Chlamys farreri by expressed sequence tag (EST) and rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of CfTNFR was of 1334 bp, consisting of a 5' UTR of 17 bp, a 3'UTR of 69 by with a poly (A) tail, and an open reading frame (ORE) of 1248 by encoding a polypeptide of 415 amino acids with a theoretical isoelectric point of 8.33 and predicted molecular weight of 47.07 kDa. There were a signal peptide, a CRD, a transmembrane region and a death domain in the deduced amino acid sequence of CfTNFR, suggesting that it was a typical type 1 membrane protein. The high identities (22-40%) of CfTNFR with other TNFR superfamily members indicated that CfTNFR should be a member of TNFR superfamily, and moreover, it should be the first death domain-containing TNFR found in invertebrates. Phylogenetic analysis revealed that CfTNFR was closely related to TNFR-like proteins from Strongylocentrotus purpuratus, Drosophila melanogaster and Ciona intestinalis, and they formed a separate branch apart from vertebrate TNFRs. The spatial expression of CfTNFR transcripts in healthy and bacteria challenged scallops was examined by quantitative real-time PCR. CfTNFR transcripts could be detected in all tested tissues, including haemocytes, gonad, gill, mantle and hepatopancreas, and significantly up-regulated in the tissues of gonad, gill, mantle and hepatopancreas after Listonella anguillarum challenge, indicating that CfTNFR was constitutive and inducible acute-phase protein involved in immune defence. The present results suggested the existence of the TNFR-like molecules and TNF-TNFR system in low invertebrates, and provided new insights into the role of CfTNFR in scallop innate immune responses to invading microorganisms. (C) 2009 Elsevier Ltd. All rights reserved.

Effects of infection of EGH-expressing Escherichia coli on haemocytes in Ciona intestinalis

The effects of infection of EGFP-expressing Escherichia coli on the haemocytes of the ascidian Ciona intestinalis were investigated. The results showed that THC of the infected individuals changed significantly. Hyaline amoebocytes phagocytosed E. coli in 5 min and excreted lysosome particles that attached to the surface of the bacteria. Granular amoebocytes released lots of particles for Immoral immunity while stem-cell-like haemocytes remained intact. With the increase in THC, the stem-cell-like haemocytes showed division and proliferation. A small portion of hyaline amoebocytes was at early apoptosis stage I h after infection and typical apoptosis bodies emerged in granular amoebocytes. A few of the infected haemocytes showed DNA damage using SCGE assay. Flow cytometry analysis revealed an obvious apoptosis peak in infected haemocytes. In conclusion, apoptosis was found to be an important immune response of ascidian haemocytes response to bacterial infection. To our best knowledge, this is the first report of the occurrence of apoptosis of haemocytes in ascidians. (c) 2005 Elsevier B.V. All rights reserved.