C194铜合金的强化机制研究

为了研究C194铜合金的强化机制，对比分析了两种成分略有不同的C194铜合金带材的力学性能及其微观组织。研究发现C194合金组织中的析出相包括α—Fe和Fe3P两种，其中α—Fe是C194铜合金的主要强化相，而不是Fe3P。如果合金中P含量较高，则多余的P与合金元素Fe结合形成金属间化合物Fe3P，并以粗大颗粒形式析出，这将导致起主要强化作用的α-Fe相数量减少，从而使材料强度降低，同时由于P对合金的导电、导热性能均有显著影响，对材料综合性能不利，因此在生产中应严格控制P的含量，且尽量取下限，抑制Fe3P的形成和析出，促进α-Fe在时效过程的弥散析出，从而达到理想的强化效果。     

Lysine 194 is functional in isocitrate lyase from Escherichia coli

BACKGROUND: Peritoneal involvement by Wilms' tumor indicates stage III disease. CT is the single preferred modality in determining the extent and staging of Wilms' tumor; however, the CT appearances of Wilms' tumor involvement of the peritoneum have not been specifically addressed in the literature. OBJECTIVE: The objective of this study was to demonstrate the CT manifestations when there is involvement of the peritoneum, mesentery and/or omentum in Wilms' tumor. MATERIALS AND METHODS: Four cases of Wilms' tumor form the basis of this report. They were examined on Elscint CT scanners. RESULTS: Masses ("dropped metastases") in the pelvis were present in all four patients. Three patients had masses in the mesentery of the small bowel and sigmoid colon. Infiltration of the greater omentum was identified in two patients as a mantle of tumor separating bowel from the anterior abdominal wall. Ascites was present in two patients. In one patient broad-based solid masses of varying sizes were noted on the parietal and on the visceral surfaces of the peritoneum, and in a different patient a discrete mass was noted in the lesser omentum. CONCLUSION: The peritoneal spaces, recesses, ligaments and folds are invisible unless invaded by disease which is well demonstrated on CT.     

C194引线框架材料生产工艺

对C194引线框架材料各个生产工序的生产工艺进行了分析和探讨，为生产出高质量的引线框架材料提供了有利的建议和参考。     

铅锌矿选矿工艺流程改造试验

针对五台山铅锌矿矿石难选、技术经济指标不理想的现状，本研究课题通过小型试验及工业试验，添加调整剂T6与捕收剂D3及现场一系列的改造，使铅、锌及其伴生金、银的精矿品位和回收率均有较大的提高，年新增经济效益206．67万元。     

Comparative analysis of the pC194 group of rolling circle plasmids

pC194-type plasmids have been isolated from widely divergent species of bacteria: Gram positive, Proteobacteria, Spirochaetes and Cyanobacteria. We have examined the three essential replication elements of these plasmids, i.e., the Rep protein, and the origins of double and single stranded synthesis. Comparative analysis of Rep protein sequences from these plasmids indicates that they are highly divergent. Those isolated from Gram positive species fall into five groups: a Bacillus group, a Lactobacillus group, a Streptococcus group and two Staphylococcus aureus groups. The two S. aureus clusters are quite separate, suggesting that there has been at least one plasmid transfer between divergent Gram positive species. The double stranded origin of replication and the active site of the Rep protein display similarities across species indicating that these motifs can function in very divergent hosts. In contrast the single stranded origin of replication is typical of the host from which the plasmid is isolated. This is exemplified by (i) pKYM where the single stranded origins are similar to the minus origins found on the single-stranded coliphages, and (ii) pTD1 (isolated from a Spirochaete), pNostoc, pMA1 and pRF1 (all isolated from Cyanobacteria) which have no sequence homology to the minus origins identified in Gram positive or Gram negative species. This points to the single stranded origin as a feature critical to the determination of the host range of the plasmid.