硅灰石粒径对PP/PP-g-MMA/W复合体系非等温结晶的影响

以甲基丙烯酸甲酯接枝聚丙烯(PP-g-MMA)为硅灰石(W)填充聚丙烯(PP)复合材料(PP/W)的界面相容剂,研究了W粒径对聚丙烯/硅灰石(PP/PP-g-MMA/W)复合体系力学性能和非等温结晶行为的影响.用Avrami方程、Ozawa、Mo、和Kissinger方法分析了复合材料非等温结晶曲线,得到n、Kc、α、F(T)、TP、T1/2和△E等参数.结果表明,W粒径对n和α影响不大;在W异相成核、W粒径和增容荆共同作用下,W粒径为400目和800目的试样,K较大,F(T)、t1/2较小,TP较高,形成的晶粒较完善、细小,提高了复合材料的塑性和韧性,特别是800目的试样塑性和韧性最好.     

A systematic, genome-wide, phenotype-driven mutagenesis programme for gene function studies in the mouse

As the human genome project approaches completion, the challenge for mammalian geneticists is to develop approaches for the systematic determination of mammalian gene function. Mouse mutagenesis will be a key element of studies of gene function. Phenotype-driven approaches using the chemical mutagen ethylnitrosourea (ENU) represent a potentially efficient route for the generation of large numbers of mutant mice that can be screened for novel phenotypes. The advantage of this approach is that, in assessing gene function, no a priori assumptions are made about the genes involved in any pathway. Phenotype-driven mutagenesis is thus an effective method for the identification of novel genes and pathways. We have undertaken a genome-wide, phenotype-driven screen for dominant mutations in the mouse. We generated and screened over 26,000 mice, and recovered some 500 new mouse mutants. Our work, along with the programme reported in the accompanying paper, has led to a substantial increase in the mouse mutant resource and represents a first step towards systematic studies of gene function in mammalian genetics.     

Kinetic analysis,size profiling,and bioenergetic association of DNA released by selected cell lines in vitro

Although circulating DNA (cirDNA) analysis shows great promise as a screening tool for a wide range of pathologies, numerous stumbling blocks hinder the rapid translation of research to clinical practice. This is related directly to the inherent complexity of the in vivo setting, wherein the influence of complex systems of interconnected cellular responses and putative DNA sources creates a seemingly arbitrary representation of the quantitative and qualitative properties of the cirDNA in the blood of any individual. Therefore, to evaluate the potential of in vitro cell cultures to circumvent the difficulties encountered in in vivo investigations, the purpose of this work was to elucidate the characteristics of the DNA released [cell-free DNA (cfDNA)] by eight different cell lines. This revealed three different forms of cfDNA release patterns and the presence of nucleosomal fragments as well as actively released forms of DNA, which are not only consistently observed in every tested cell line, but also in plasma samples. Correlations between cfDNA release and cellular origin, growth rate, and cancer status were also investigated by screening and comparing bioenergetics flux parameters. These results show statistically significant correlations between cfDNA levels and glycolysis, while no correlations between cfDNA levels and oxidative phosphorylation were observed. Furthermore, several correlations between growth rate, cancer status, and dependency on aerobic glycolysis were observed. Cell cultures can, therefore, successfully serve as closed-circuit models to either replace or be used in conjunction with biofluid samples, which will enable sharper focus on specific cell types or DNA origins.     

Proliferationen der Fischepidermis nach der Einwirkung von inhibitoren des glykolytischen Energiestoffwechsels

Summary When fluoride-ions or monoiodoacetate is added to the ambient medium, there occur in fish larvae after 12 h, and in eels after 24 h, in some places, solid epidermal proliferations. The effect of glycolysis inhibitors on epidermal mitotic activity might be due to an impairment of energy metabolism as it is nullified by a simultaneous application of inorganic diphosphate or by doubled O₂ partial pressure of 320 mm Hg.     

Systemic methods for the analysis of failure

For more than 20 years systems-related ideas have been used to analyze and model failures and disasters of various sorts. The authors outline some examples of the links that have been forged between failures and systems over this period. An overview of the origins and development of systems failures teaching and research at the United Kingdom Open University is also presented, together with two systemic methodologies for the analysis of failure that have stemmed from this work. The implications of recent research on the application of the more sophisticated of these two methodologies are also discussed.     

Fulminant hypertension in transgenic rats harbouring the mouse Ren-2 gene

PRIMARY hypertension is a polygenic condition in which blood pressure is enigmatically elevated; it remains a leading cause of cardiovascular disease and death due to cerebral haemorrhage, cardiac failure and kidney disease. The genes for several of the proteins involved in blood pressure homeostasis have been cloned and characterized, including those of the renin-angiotensin system, which plays a central part in blood pressure control. Here we describe the introduction of the mouse Ren-2 renin gene into the genome of the rat and demonstrate that expression of this gene causes severe hypertension. These transgenic animals represent a model for hypertension in which the genetic basis for the disease is known. Further, as the transgenic animals do not overexpress active renin in the kidney and have low levels of active renin in their plasma, they also provide a new model for low-renin hypertension.