PET短纤维和长丝：生产工艺的发展趋势

聚酯短纤维和长丝的消费不断增长，这给商业增长提供了巨大的机会，但同时，世界范围的竞争日趋激烈。今天为了保持市场竞争力，作出正确决定变得越来越重要。本文的目的是从技术角度剖析赢得经济挑战的一些基本因素。     

Female x male interactions in Drosophila sperm competition

In several organisms, the success of a male's sperm in multiply inseminated females depends on the male's genotype. In Drosophila, the female also plays a role in determining which sperm are successful. Pairwise tests among six isogenic lines of Drosophila melanogaster were performed to determine whether there is a genotype-specific interaction in the success of sperm. The success of a particular male's sperm was found to depend on the genotype of the female with which he mates, providing evidence for an interaction with profound evolutionary consequences.     

Chain length of the polylysine in receptor-targeted gene transfer complexes affects duration of reporter gene expression both in vitro and in vivo

Complexes composed of peptide ligand for the serpin enzyme complex receptor covalently coupled to poly-L-lysine condensed by charge interaction with plasmid DNA direct gene transfer into receptor bearing cells. We compared intensity and duration of reporter gene expression in vitro and in vivo from serpin-enzyme receptor-directed gene transfer complexes prepared with poly-L-lysine of different chain lengths. When substituted with linker and ligand to comparable extents, DNA complexes containing short chain poly-L-lysine were larger and gave higher peak expression but significantly shorter duration of expression than those containing long chain poly-L-lysine. Both peak expression and duration of expression exceeded that observed with Lipofectin. Neither naked DNA nor DNA complexed with unsubstituted polylysine was effective in gene transfer. For in vivo experiments, complexes containing optimal ligand and degree of substitution (based on in vitro data, peptide C105Y, 11 ligands/plasmid DNA molecule) were prepared with either short chain or long chain polylysine and a beta-galactosidase expression plasmid. Following injection into the tail veins of mice, longer chain complexes gave significantly higher expression of reporter gene in lung and spleen that lasted for a significantly longer period of time than the shorter chain complexes. The short chain poly-L-lysine-DNA complexes were larger in diameter, as assessed by electron microscopy or atomic force microscopy, and gave less protection against DNase digestion in vitro than longer chain complexes. Thus, for gene transfer complexes directed at the serpin enzyme complex receptor, longer chain poly-L-lysine gave a much longer duration of expression both in vitro and in vivo. We speculate that this may be due to protection against degradation afforded the plasmid DNA by the tighter compaction produced by long chain poly-L-lysine.     

丝光废碱的有效净化

目前丝光处理棉产生的淡烧碱通常都进行回收，但此循环过程造成碱液中的杂质积累。本文介绍了用双氧水净化浓缩的回收碱液的重要意义和处理方法。     

Retrospective analysis of the Beijing family of Mycobacterium tuberculosis in preserved lung tissues

Direct repeat spoligotyping of 85 paraffin-embedded lung biopsies was used to investigated the occurrence around Beijing of the Beijing family of Mycobacterium tuberculosis. Samples ranged in time from 1956 to 1990. Hybridization patterns were found with 49 (58%) samples, and 45 (92%) produced typical Beijing family patterns extending over the 34-year period.