用于后端工艺中铜/低k材料金属去除的实验数值研究

1 Introduction The consumer electronics market demands high-er speeds and more functionality of ICs. Speed and functionality of an IC are related to the amount of cir- cuitry (such as transistors), which is packed on eachchip. Therefore, the dimensions of the transistors need to be reduced. The interconnect structure, which con- nects the transistors, must become smaller too to com- ply with the small dimensions of the transistors. In or- der to reduce undesirable effects[1], which follow fr…     

Comparative analysis of viral pathogens and potential indicators in shellfish

Shellfish can be responsible of outbreaks of infectious diseases and current health measures do not guarantee the absence of viral pathogens in this product. Here we examine the presence of pathogenic viruses and potential indicators in shellfish in a comparative analysis.Sixty shellfish samples collected in three areas with different levels of faecal contamination were analysed for Escherichia coli, total coliforms, Clostridium perfringens, somatic coliphages, F-specific phages of RNA (F-RNA), bacteriophages infecting Bacteroides fragilis RYC2056, human adenovirus, enterovirus and hepatitis A virus (HAV). Viruses were eluted in a glycine buffer at pH 10.The overall percentage of viral pathogens detected was 47% for human adenoviruses, 19% for enteroviruses and 24% for HAV. Since all the samples positive for enterovirus and HAV were also positives for human adenovirus, the latter may be considered useful as a molecular index of viral contamination in shellfish. No significant differences in the bioaccumulation of bacteria and bacteriophages for oysters or mussels were observed. It was found that the probability of detection of any of the pathogenic virus decreases as the temperature of shellfish growing waters increases. However, the probability of detecting viruses increases when phages of B. fragilis are found. Although more data are needed in order to fulfil the need of viral indicators for controlling the presence of human viruses in shellfish, the obtained results indicate that phages infecting B. fragilis RYC2056 could be a suitable group of bacteriophages to be used as an indicator of the presence of viruses in shellfish.     

Analysis of Salmonella serotypes from selected carcasses and raw ground products sampled prior to implementation of the Pathogen Reduction; Hazard Analysis and Critical Control Point Final Rule in the US

In July 1996, the US Department of Agriculture (USDA), Food Safety and Inspection Service (FSIS), published the Pathogen Reduction; Hazard Analysis and Critical Control Point (HACCP) Systems final rule to improve food safety of meat and poultry products. The final rule established, among other requirements, pathogen reduction performance standards for Salmonella for food animal carcasses and raw ground products. The final rule is to be fully implemented in three stages in successively smaller federally inspected meat and poultry slaughter and processing establishments. Implementation began in January 1998 and was completed in January 2000. Samples of carcasses of four species of food animals (cattle, swine, chickens, turkeys), and raw ground product from each of these species, were collected by FSIS from establishments prior to implementation of the final rule and cultured for Salmonella. This paper reports Salmonella serotype results of samples collected from June 1997 through August 1998. These results represent a baseline for future comparisons.     

大西洋新生代有孔虫铁锰氧化物覆膜中的稀土元素及钕同位素

利用有孔虫方解石铁锰氧化物覆膜物质确定新生代时期海水的稀土元素含量、稀土模式和Nd同位素组成,本文对这个方法进行了评述.取自里奥格朗德洋中脊(DSDP·357点位)0～60百万年的样品的研究结果表明,氧化物覆膜与现代样品稀土元素含量基本一致.虽然新生代样品表面覆膜原始~(143)Nd/~(144)Nd比值似乎得到了保存,但在亚氧化条件下由于成岩作用的改造,其REE配分模式发生了明显的变化.尽管南大西洋新生代海水~(143)Nd/~(144)Nd比值变化的范围没有超出所观察到的现代海水该比值的范围,但Nd同位素曲线具有明显的随时间变化的趋势.除年龄最老的样品外,有孔虫的Nd和Sr同位素组成反比关系.Nd、Sr同位素之间的反比关系不仅反映了大陆带入和短期海底火成岩碎屑风化作用使Nd、Sr含量的相对比例发生了全球性的变化,而且也揭示了在局部范围内Sr同位素曲线变化是不灵敏的,显示出两元素对海洋物质输入作用的响应时间不同.Nd同位素是一种很有前景的海洋古化学的示踪物.     

Effects of dietary supplements of zinc-methionine on milk production,udder health and zinc metabolism in dairy goats

Twenty-two Murciano-Granadina dairy goats were used to investigate the effects of organic Zn supplementation of a diet containing a high level of inorganic Zn. Goats were kept in pens, machine milked once a day throughout lactation and fed a diet based on a dehydrated mixture of whole-plant maize and alfalfa ad libitum, alfalfa pellets, barley grain and a concentrate mixture. Treatments were: (1) control, and (2) supplemented with 1 g/d Zn-Methionine (Zn-Met) included in the concentrate mixture. After parturition, goats were blocked in week 3 and dietary treatments were applied until week 23. From weeks 3-20, feed intake, milk yield, milk composition, milk somatic cell count (SCC), and udder health were measured. In week 21, all goats were injected intraperitoneally with 1 g/d DL-methionine for 5 d to establish the effects of methionine under the conditions of udder stress induced by hand milking on the second day. During weeks 22 and 23, diet digestibility, and N and Zn balance were determined. Dry matter intake, milk yield, and milk contents of total solids, fat, total and true protein, and casein did not differ between treatments, but whey protein and non-protein nitrogen contents were significantly lower for the Zn-Met group. Milk SCC tended to decrease as a result of Zn-Met supplementation but differences between treatments were not significant when halves with persistent infection were excluded. Hand milking increased SCC in both groups, but udders of supplemented goats showed a lower reaction. Apparent absorption of N significantly increased and Zn retention tended to increase in Zn-Met supplemented goats. We conclude that Zn-Met supplementation can enhance resistance to udder stress in dairy goats. Effects were attributed to the organic Zn and not to the methionine component. Zn retention and protein utilization were also improved by the Zn-Met supplement.     

高强高模聚乙烯纤维

近十年来,通过取向和链伸展来改善高聚物的机械性能已成为一个重要的研究方向。高聚合度聚乙烯是应用于这方面研究的重要对象,这是由于对聚乙烯进行结构改性可达到它最大的理论强度和模量(表1)。     

新型纺丝油剂在产业用纤维及轮胎帘子线中的应用

在过去的20年中,聚酯和聚酰胺复丝在产业领域的应用日益扩大,主要用于生产安全充气袋、结构材料、传送带、渔网、层压织物、安全带、帆布、帐篷、轮胎帘子线、防水油布和V型带。所有上述产品的共同要求是:高性能的纤维,即高强、低收缩、高模、低伸长。     

Genome-wide bacterial toxicity screening uncovers the mechanisms of toxicity of a cationic polystyrene nanomaterial

By exploiting a genome-wide collection of bacterial single-gene deletion mutants, we have studied the toxicological pathways of a 60-nm cationic (amino-functionalized) polystyrene nanomaterial (PS-NH(2)) in bacterial cells. The IC(50) of commercially available 60 nm PS-NH(2) was determined to be 158 μg/mL, the IC(5) is 108 μg/mL, and the IC(90) is 190 μg/mL for the parent E. coli strain of the gene deletion library. Over 4000 single nonessential gene deletion mutants of Escherichia coli were screened for the growth phenotype of each strain in the presence and absence of PS-NH(2). This revealed that genes clusters in the lipopolysaccharide biosynthetic pathway, outer membrane transport channels, ubiquinone biosynthetic pathways, flagellar movement, and DNA repair systems are all important to how this organism responds to cationic nanomaterials. These results, coupled with those from confirmatory assays described herein, suggest that the primary mechanisms of toxicity of the 60-nm PS-NH(2) nanomaterial in E. coli are destabilization of the outer membrane and production of reactive oxygen species. The methodology reported herein should prove generally useful for identifying pathways that are involved in how cells respond to a broad range of nanomaterials and for determining the mechanisms of cellular toxicity of different types of nanomaterials.     

聚氯乙烯的高温热裂解—分子内部形成芳香烃的论证

我们用热裂解—气相色谱—质谱测定法和红外光谱分析对聚氯乙烯热裂解所产生的挥发物的化学结构进行了分析。重氢示踪的氯乙烯在环己烷存在下,在60℃聚合而成。热裂解在充有氮气和氧气的CDSPyroprobe中进行。用全氘聚氯乙烯和α—氘聚氯乙烯所进行的实验表明,上述聚合物在热裂解物中的同位素分布与主要形成芳香族化合物(苯,甲苯和萘)的分子内机理完全一致。