The structure of consolidated rapidly solidified powders of Ni3Al

Rapidly solidified powders of stoichiometric Ni₃Al and Ni₃Al containing boron and titanium have each been consolidated by two distinct routes, namely hot extrusion or hot compaction. The resulting microstructures have been examined by optical microscopy, scanning electron microscopy and transmission electron microscopy. The consolidated material did not retain the non-equilibrium structure of the rapidly solidified powders. The addition of titanium and boron produced material with a larger final grain size, a decreased incidence of twinning and, in the extruded material, led to cracking. Although all processing was performed in inert atmospheres, oxides were present in all consolidated products.     

Is duodenal gastric metaplasia a consequence of Helicobacter pylori infection in children?

BACKGROUND: Duodenal gastric metaplasia (DGM) is commonly found in association with Helicobacter pylori (Hp)-associated gastritis in adults. DGM is also considered a risk factor for duodenal ulcer development. The prevalence of DGM in children and its association with gastritis, duodenitis, or the presence of Hp organisms is not clear. We investigated the prevalence of DGM in children and explore its association with several possible risk factors, including age, gender, gastritis, duodenitis, or Hp presence in the gastric antrum. METHODS: A retrospective analysis of 173 upper endoscopy procedures performed between 1993 and 1995 at Cabell Huntington Hospital, Huntington, WV, was done. Gastric and duodenal biopsies were stained with Giemsa for Hp detection, periodic acid-Schiff for DGM, and hematoxylin and eosin for histologic assessment. Gastric mucosal inflammation was graded according to Sydney criteria. RESULTS: Duodenal gastric metaplasia was identified in 23 of 173 (13%) patients. Duodenitis but not age, gender, gastritis, or the presence of Hp in the gastric antrum was associated with DGM development. In 4 of 23 DGM foci, Hp was identified. CONCLUSIONS: In children, DGM is not the consequence of Hp infection.     

Compromised allograft rejection response in transgenic mice expressing antisense sequences to retinoic acid receptor beta2

Our aim was to identify new genes involved in the cellular aspects of defense mechanism of Drosophila, as well as in melanotic tumor formation processes that are linked to blood cell disregulation. We have screened 1341 enhancer detector fly lines for expression of the lacZ reporter gene in larval hemocytes at the end of the third instar. We have selected 21 lines in which we observed a reproducible lacZ expression in blood cells. These lines were classified according to the subsets of hemocytes in which lacZ was expressed, and we identified five lines that can be used as lamellocyte markers. Three lines were selected for further analysis. The first exhibited strong lacZ expression in all lamellocytes. The second expressed lacZ in plasmatocytes and lamellocytes, and exhibited a melanotic tumor phenotype in larvae homozygous for the insertion. A third line showed a striking insertion-linked phenotype of melanized lymph glands (the hematopoietic organ), which resulted in the total absence of circulating hemocytes in the mutant larvae. We anticipate that this mutation, which we named domino, will prove a useful tool in the analysis of the role of hemocytes during the various aspects of immune response and melanotic tumor formation.     

构皮滩水电站观景供水系统大型长轴深井泵站设计

乌江构皮滩水电站大坝上游的观景供水系统，为满足上游水位变化的需要，设计成分阶段分级竖井供水的方式。供水设备选用高工效、低能耗的RJC型大型长轴深井泵，运行方式为开敞式串联运行，单机单台生产能力为1010m3／h，最大扬程96．51m，最大井下安装深度89．475m，经安装调试运行效果良好。大型长轴深井泵在乌江构皮滩水电站供水系统中的成功应用为中国类似工程泵站设计提供了很好的借鉴，也将促进中国大型长轴深井泵的进一步发展。