稀土在热浸镀铝中的行为和分布研究

分别在工业纯铁和20碳钢上制备了热浸镀纯铝和稀土铝镀层,采用扫描电镜(SEM)观察了镀层横截面和表面的形貌,采用能谱仪(EDS)和电子探针(EPMA)分析了镀层横截面的稀土分布.结果表明,添加稀土热浸镀铝后,表面层厚度减少,合金层厚度增加;镀层表面比较平整、连续、无裸露点、裂纹和氧化物夹杂,且FeAl3相短而细小;稀土渗入了镀层,且分布很不均匀,在部分区域存在偏聚,表面层与合金层界面处以及齿状Fe2Al5相的边缘处和齿尖处稀土含量较高.分析了稀土对镀层厚度和组织形貌的影响及稀土的渗入机理.     

铌、钨和硼在TiAl基合金中的分布及其对组织的影响

铌、硼和钨在TiAl基合金中的存：在形式、分布状态与该合金的制备片法、加工工艺及热处理制度有密切的联系，它们对TiAl基合金的性能又有重要影响。为进一步对有关问题进行研究，该文对铌、钨、硼在TiAl基合金中的作用进行了综合分析，对铸造法制得的Ti-Al-Nb-W-B合金进行了热等静压和均匀化处理，并对微观金相组织进行了观察比较。结果表明：Ti-45Al-7Nh合金中添加少量的钨和硼，能使晶团尺寸明冠细化，达40μm。随钨含量的增加，晶团尺寸越来越小，片层间距则越来越大，如Ti-45Al-7Nb-0．15B的晶团尺寸约为100μm，片层间距约为1．2μm；Ti-45Al-7Nb-0．2W-0．15B的晶团尺寸约为70μm，片层间距约为1．6μm；Ti-45Al-7Nb-0．4W-0．15B的晶团尺寸约为50μm，片层间距约为1．7μm；Ti-45Al-7Nb-0.7W-0．15B的晶团尺寸约为40μm，片层间距约为1．8μm。钨含量达到0．4％以后，晶团细化及片层间距增加的效果使渐趋稳定。     

火车车轮轮辋组织与显微硬度的统计分布表征

采用高通量场发射扫描电镜结合图像批处理技术以及全自动显微维氏硬度分析技术对2种不同成分(W1和W2)的火车车轮轮辋踏面附近较大范围内的显微组织和硬度进行了原位统计分布表征,探究了轮辋靠近踏面的关键区域铁素体面积分数和珠光体片层间距的分布规律.通过大尺度原位统计分布表征结果可以发现,2种车轮铁素体面积分数自踏面往里均呈现...     

库尔特激光粒度分布仪在测定钽铌复合物粒度分布中的应用

文章介绍了应用库尔特激光粒度分布仪测定钽铌复合物粒度分布的方法。钽铌复合物颗粒均匀分散在二次去离子水中,以一定的流速通过激光束。衍射光经透镜被光电探测器接收转化为电信号,由此测出颗粒的粒度分布,并讨论了应用中的经验。该方法容易建立,精密度高,能够给出多种粒度分布结果以及参数,非常适合生产过程中的应用。     

外源稀土在封闭小水域中的分布与迁移

本文研究了外源稀土进入湖泊后在鱼、水及底泥中的分布及富集规律。结果表明：外源稀土进入湖泊后，在底泥中含量最高，鱼中次之，水中最低；各组分中稀土占有率以底泥中居多，水中次之，鱼中最少，但鱼中稀土占有率随时间延长而近于直线上升。实验发现，随着时间的变化，一组分中的稀土会转移到另一组分中。文中还指出鱼对稀土的生物浓缩因子在９０天时达最高值。     

体积权重与个数权重晶粒体积分布特征的相互关系

金属多晶体三维晶粒尺寸分布常近似呈Gamma分布或Lognormal分布．基于这2种分布函数,导出了体积权重与个数权重的晶粒体积分布特征多量的相互关系,并利用一种低碳钢奥氏体晶粒组织的实验数据及文献数据对其进行了验证．利用该关系,通过对多晶材料晶粒组织二维截面的标准金相测量,即可计算个数权重的三维晶粒体积分布的特征参量．     

高炉布料与煤气分布

重点阐述了高炉布料与煤气分布的关系.认为,风量过大,是导致高炉边缘发展的重要原因,适当控制风量是改善煤气利用率和延长高炉寿命的重要途径;利用时间参数,连续地比较径向煤气温度变化是判断煤气分布的有效方法.     

高铁车轮轮辋部位元素的原位统计分布分析方法研究与应用

为实现大尺寸车轮剖面的成分快速定量统计分布表征,研究了基于火花源原位统计分布分析技术的高铁车轮成分定量分布表征方法,并将该表征方法应用于3种不同成分的高铁车轮(W1、W2、W3)轮辋剖面处的成分定量统计分布分析,获得了踏面附近至轮辋内部的成分定量分布规律,并探讨了3种车轮在元素偏析行为上的差异.结合扫描电镜和能谱分析对...     

MgO在烧结矿中分布规律的研究

目前MgO在烧结矿中研究大多在烧结工艺层面,即MgO对烧结矿冶金性能的影响,但对于烧结过程来说,研究的还比较少,特别是不同烧结条件下MgO在烧结矿中的分布规律还没有系统的介绍。通过烧结实验和X射线衍射,系统分析了MgO在不同碱度、不同温度、不同Al2O3含量等条件在烧结矿中的分布规律,为合理的烧结配矿提供理论依据。     

甘肃省铅锌资源分布与产能变化趋势分析

文章结合本次全国矿产资源利用现状调查省级单矿种成果汇总工作,对甘肃省铅锌资源分布做了基本介绍,对开发利用现状进行调查分析,对未来产能变化趋势做了静态分析,并提出了一些资源开发利用建议。将甘肃省铅锌资源进行开发利用和后备产能进行分析之后提出,甘肃省铅锌资源开发将走大中型矿山提供基础保障,小型及铅锌伴生矿山做后备补充的路线。     

萍水河水质空间分布特征及水质评价对比研究

流域水质直接关系到人体健康和生态安全。以萍水河向阳湖至何雁桥段为研究对象,分析其水质空间特征,综合4种方法进行水质评价,进一步利用多元统计和级别差方法对比分析水质评价结果。结果表明：1)COD、NH₃-N、TP和TN的最高浓度位于赤山桥处;上游(向阳湖-桥头村)和下游(赤山桥-何雁桥)总体水质较好,部分采样点TN、Fe和Mn轻度超标,污染程度明显弱于中游(桥头村-赤山桥)。2)最差水质级别均为Ⅴ类或劣Ⅴ类水,污染程度属严重污染及以上;单因子评价法确定总氮(TN)为首要污染指标;主成分分析法确定2个主成分,可解释为营养盐污染指标和地质沉积环境指标。3)4种方法两两之间呈显著正相关,相关系数为0.937～0.994,但水质级别表现出明显的差异性;级差法结果表明,3种综合水质评价方法的水质级别顺序为：内梅罗污染指数法<综合污染指数法<主成分分析法。研究成果可为流域水质评价工作和研究提供参考,同时为流域水资源开发利用和水环境保护及综合治理提供科学依据。     

Methamphetamine modulates ACh-evoked currents in Xenopus occytes expressing the rat alpha7 receptors

Growth/differentiation factor 5 (GDF5), a novel member of the transforming growth factor beta superfamily, promotes the survival of dopaminergic neurones in vitro. We present here the first evidence for a neuroprotective action of GDF5 in vivo. We investigated the effects of intracerebral administration of GDF5 on a rat model of Parkinson's disease. GDF5 was administered just above the substantia nigra and into the lateral ventricle immediately before ipsilateral injection of 6-hydroxydopamine into the medial forebrain bundle. GDF5 prevented the development of amphetamine-induced rotations and preserved the integrity of striatal dopaminergic nerve terminals, as measured by positron emission tomography. Post-mortem studies showed that GDF5 spared dopamine levels in the striatum and tyrosine hydroxylase positive neurones in the midbrain. This study suggests that GDF5 has potential for the treatment of Parkinson's disease.     

Methamphetamine causes lipid peroxidation and an increase in superoxide dismutase activity in the rat striatum

The administration of methamphetamine to experimental animals results in damage to nigrostriatal dopaminergic neurons. In the present study, we demonstrated that both the acute repeated and the chronic administration of methamphetamine causes an increase in thiobarbituric acid reactive substances, which are indicators of lipid peroxidation, and superoxide dismutase activity in the rat striatum. The results of present study strengthen the notion that reactive oxygen species may play an important role in the methamphetamine-induced neurotoxicity.     

农村小额信贷模式的比较法研究

针对农村小额贷款模式问题,指出格莱珉模式虽然是世界上运作最为成功的小额信贷,但由于国情的巨大藩篱,该模式中的一些具体操作技术并不能有效地解决中国的小额信贷实践所遭遇的困顿.因此,通过比较研究的方法,检讨我国移植该模式的现实土壤及借鉴该模式所面临的困境,有利于把小额信贷的制度创新契合于城乡金融统筹发展的进程之中,进而在城乡一体化的背景下,探寻中国农村小额信贷模式的独特发展路径.     

项目教学法在英语与德语比较研究中的应用

比较英语和德语异同是每个第二外语习得者的习惯,如同每个学习英语的人一定要和母语比较一样.把在职业教育中普遍实行的项目教学法移植到英语与德语比较研究中是一个尝试,实践过程中,传统的"讲授式"教学被"研究型""体验性""参与型"取代.符合教育部国家"十五"高校课型教改的思路.实践证明,此法在语言教学中实施是可行的,有理论完善的空间.     

Methodological considerations in the assessment of acquiescence in the MA and SD scale.

This paper cites certain limitations in making assessment of acquiescence in personality scales by the use of reversed items and the Helmstadter technique. Inadequate item reversals may have contributed to the interpretation by Adams and Kirby (1936) that the SD scale was confounded with acquiescence, a finding not supported here when original items only are used. A criterion of adequate reversal, derived from SD research, may aid in developing "balanced" scales. Precautions in making acquiescence interpretations from the Helmstadter model include the confounding of content and set scores in the formulas, the confounding of response style and trait responses, lack of evidence on what the set score measures, and the uncertainty over the nature of acquiescence and how to measure it. (27 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temperature and strain rate sensitivity of the SD effect in saturation cycling

The strength differential effect during push-pull ~2 pct strain cycling was studied in AISI 310, α-brass, Cu, Ni, Al, Nb and Fe (Armco and Ferrovac E) at ~175 K. There is a small SD effect in Nb and Cu, none in the remaining fcc alloys, and a sizeable one in the interstitial Fe alloys. The latter were further investigated in the temperature range from 294 to 83 K; in addition values ofda/d In ε were determined in the Armco iron by stress relaxation. A direct manifestation of the SD effect is that the values determined in compression of the thermally activated stress term σ* and ofdσ/d In ε are at all temperatures in the ratio 1.14:1 to the homologous values obtained in tension. It is concluded that the SD effect is caused by a linear variation of σ* with hydrostatic stress; σ* appears to be the only plastic deformation parameter directly affected by it. Formerly a Post Doctoral Fellow on a Fellowship provided by the Netherlands National Science Foundation FOM, Laboratorium voor Fysische Metaalkunde     

Patterns of Brain Activation Associated With Contextual Conditioning to Methamphetamine in Mice.

Classical conditioning is thought to play a key role in addiction. The authors used c-Fos immunohistochemistry to demonstrate a conditioned physiological response to methamphetamine (meth) in mice. Male outbred mice were placed into an environment where they had previously experienced 2 mg/kg meth or saline. The meth-paired mice displayed increased c-Fos in several brain regions, including the nucleus accumbens, prefrontal cortex, orbitofrontal cortex, basolateral amygdala, and bed nucleus of the stria terminalis. No conditioned locomotor activity was observed, but individual activity levels strongly correlated with c-Fos in many regions. A batch effect among immunohistochemical assays was demonstrated. Results implicate specific brain regions in classical conditioning to meth and demonstrate the importance of considering locomotor activity and batch in a c-Fos study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparative Study of the Variables in Construction Project Briefing/Architectural Programming

Briefing is the process by which client requirements are identified, clarified, and articulated in the early design stage of construction projects. It is crucial to the successful delivery of construction projects. Considerable research has been conducted in briefing during the past two decades. However, researchers consider many current briefing practices to be inadequate, and little research has been done in sufficient depth to explore briefing variables in the construction industry. This paper introduces a comprehensive framework of the variables that have an impact on construction project briefing. A questionnaire survey was conducted to validate these variables among project managers and architects in Hong Kong, the United Kingdom, and the United States. The results indicate that although no significant differences existed between the samples in the United Kingdom and the United States on the variables for construction project briefing, the views of the samples in Hong Kong deviated from the two Western countries. The Western professionals have more positive answers to most statements in the questionnaire. The findings have significant implications for industry practitioners in producing their guidelines for the briefing process and for writers in drafting how-to briefing guide for construction projects.