FeMnAlC TWIP钢加热过程中的氧化行为GD-OES研究

摘要：以成分（质量分数）为Fe-16%Mn-1.5%Al-0.6%C-0.11%Cr的TWIP钢为研究对象，采用模拟试验研究了加热过程中的氧化行为，使用GD-OES分析了加热温度和加热气氛中O2含量对表面元素深度分布的影响。结果表明，当TWIP钢在N2-0.05%（体积分数）O2的气氛中加热至550~700℃时，表面会形成Fe-Mn氧化层，次表层会形成贫锰层、脱碳层及内氧化层，各层厚度随加热温度升高而增大。在氧化性气氛中加热时，Al元素优先在次表层形成内氧化，少量的Cr元素在氧化层/基体界面上形成外氧化，表面氧化层中基本不含Al和Cr。当加热温度为650℃时，气氛中O2体积分数在0.025%~0.2%之间变化对氧化层厚度影响较小，均可获得厚度介于400~500nm的氧化层。由此可见，为获得TWIP钢合适的预氧化层厚度，同时减少预氧化层/基板界面位置的氧化物，直火加热出口温度控制比空燃比控制更重要。     

Nb对铸造双相耐热钢高温氧化的影响

摘要：为探究Nb对双相耐热钢高温抗氧化性能的影响规律，采用扫描电镜、能谱分析和XRD等分析测试手段研究了1000和1100℃下含Nb双相耐热钢高温氧化性能。结果表明，双相耐热钢氧化层结构为氧化外层(MnCr2O4)→氧化内层(Cr2O3)→Si的内氧化层；Nb的加入加速双相耐热钢的表层氧化膜生长，降低了其抗氧化性能；随着Nb含量的增加，表层基体内部形成富Nb相，促进Si的沿晶界氧化而抑制Si的界面氧化，Cr2O3层和Si的内氧化层厚度均增加。在对高温抗氧化性能要求高的情况下，本双相耐热钢中Nb的质量分数应控制在0.8%以下。     

Ni-Ti-Cr固溶体对Ti(C,N)基金属陶瓷组织和性能的影响

以机械合金化的Ni-Ti-Cr固溶体作为粘结剂制备了Ti(C,N)基金属陶瓷，研究了不同Cr含量的固溶体对金属陶瓷微观组织、力学性能和氧化行为的影响。结果表明，随着Cr含量的增加，金属陶瓷颗粒尺寸先减小后增大，抗弯强度、断裂韧性和硬度先增大后减小。当Ni、Ti、Cr的质量比为91∶3∶6时，金属陶瓷的综合性能最好，抗弯强度、断裂韧性和硬度分别达到2 120.3 MPa、15.41 MPa·m^1/2和88.9 HRA,且氧化膜致密，氧化增重和氧化膜剥落较少。金属陶瓷经过60 h氧化后，外层氧化膜以NiO为主，TiO₂主要嵌在NiO晶界处，往内为疏松的TiO₂层，再往内Cr元素富集，形成致密的NiO和NiCr₂O₄层，可有效吸收氧原子，阻碍进一步氧化，并起到层与层之间连接和过渡的作用。在循环氧化时，金属陶瓷氧化膜经历了从NiO层到TiO₂层循环剥落的过程。     

冷轧硅钢片表面氧化层厚度的金相测定方法探讨

对冷轧硅钢片脱碳退火过程中表面生成的极薄氧化层形态特征和厚度测定方法的研究认为，无取向钢的氧化层沿晶界呈网络状，取向钢则沿基体表面呈薄层状；还认为，施以纵轧面上的小角度倾斜法，即对横向斜截磨面上的金相图象进行测定，其波浪形氧化层清晰均匀，重复性好，具有一定的代表性，同时还提出了运用“相似三角形对应边成正比”的关系式快速测算氧化层厚度的方法。本方法可广泛应用于钢板表面各种极薄层的测定。     

加热速率对钢筋氧化动力学影响规律的研究

通过热重分析方法和显微结构观察，研究了耐腐蚀钢筋不同加热速率下的氧化规律，并与等温氧化过程做了对比。结果表明，不同加热速率下钢筋的显微组织并没有明显差异，但是氧化层厚度随着加热速率的减小而增加。当加热速率小于10℃/min时，氧化层呈现明显的双层结构，但当加热速度为20℃/min时，氧化层几乎呈现单层结构。通过恒速加热试验建立了一种新的氧化活化能计算方法，与等温氧化试验所得值相比，加热速率为5、10、20℃/min时的相对误差分别为4.14%、5.12%和32.13%，因此，为了保证新方法的精度，试验需在较低的加热速率下进行。     

高温氧化对钛合金超塑性能的影响

研究了Ti-6Al-4V合金在800℃、850℃和900℃高温条件下进行拉伸试验时空气氧化对超塑性能的影响。通过光学显微镜、扫描电镜和X射线衍射分析了该钛合金氧化层的微观形貌和成分组成，并研究其在高温拉伸下的氧化机理。结果表明，高温氧化导致该合金在高温拉伸过程中表面产生氧化层，而在拉伸应力作用下氧化层断裂并向基体扩展，从而严重降低了Ti-6Al-4V合金的超塑性，但不会影响其抗拉强度及屈服强度。     

内氧化层对高牌号无取向硅钢磁性的影响

通过金相法和磁声发射法（ＭＡＥ）研究了高牌号无取向硅钢脱碳退火时所产生的内氧化层，这种氧化层使钢板产生应力场，阻碍磁畴壁的位移，因而使铁损增加。     

日本分析不锈钢用稀有金属镍、铬、钼

1镍 资源 镍矿石主要分为两大种类——硫化矿和氧化矿，硫化矿的出产国主要是俄罗斯、加拿大、澳大利亚、南非、中国等国家，因存在于地表深层所以采掘成本高，但是它含有铜和贵金属，从副产品中可以得到收入。氧化矿主要出产于印度尼西亚、菲律宾、新喀里多尼亚、古巴等接近赤道的热带和亚热带国家，氧化矿存在于地表附近，在地表土下呈两层结构，第一层含镍1％左右，第二层含镍2％～3％。以前第二层矿主要用于生产镍铁合金的原料，第一层矿却难以利用。近年来确立了HPAL（高压硫酸浸出）法工艺，可以期待第一层矿将成为今后生产镍的主体原料。镍的资源量为：氧化矿约1．35亿吨镍，硫化矿约0．61亿吨镍。     

3.5Ni低温压力容器钢氧化层结构特性分析

以3.5Ni低温压力容器钢为研究对象,模拟其加热过程,采用扫描电子显微镜分析了其加热后表面氧化层的显微结构。结果表明:3.5Ni低温压力容器钢的氧化层分为疏松氧化层和致密氧化层,疏松氧化层冷却过程中易鼓起脱落,致密氧化层的外部为一层连续的镍铁金属富集层,将金属氧化物包裹其中,具有一定的强度和韧性,是3.5Ni低温压力容器钢氧化铁皮难以除尽的主要原因。     

FeS的水蒸泡高温氧化动力学

通过测定脱硫速度，研究了ＦｅＳ的水蒸汽高温氧化动力学。ＦｅＳ的水蒸泡氧化产物为Ｆｅ３Ｏ４，未反应物转为成类磁黄铁矿相（Ｆｅ１－ａＳ）。反应初斯铁先于硫被氧化，较致密的Ｆｅ３Ｏ４产物层形成后，硫与铁同时被氧化，实验数据与界面化学反应和固体产物层扩散共同控制数学模型结果相吻合。反应活化能和扩散活化能分别为１２２．０ＫＪ／ｍｏｌ和９０．２ＫＪ／ｍｏｌ。增中水蒸泡流量可使产物层粒度变细，孔隙度降低。流量为     

Transmitter-induced calcium responses differ in astrocytes acutely isolated from rat brain and in culture

Glial fibrillary acid protein (GFAP)-positive astrocytes isolated from the cerebral cortices of 3-10-day-old rats frequently showed increased intracellular Ca2+ concentration responses to L-glutamate and glutamate analogues. However, few of the acutely isolated cells responded to ATP, and no such cells responded to serotonin [5-hydroxytryptamine (5-HT)]. The same cell that failed to respond to ATP or 5-HT often responded to glutamate. Culturing acutely isolated cells in media containing horse serum decreased Ca2+ responses to glutamate but increased the responses to ATP and induced responses to 5-HT. In primary cultures prepared from the cerebral cortices of 1-day-old rats and cultured in horse serum, fewer of the cells responded to glutamate, but almost all cells responded to ATP and 5-HT. The lack of or limited response to, 5-HT or ATP in the acutely isolated cells seems unlikely to be due to selective damage to the respective receptors because acutely isolated GFAP-negative cells showed responses to ATP, several different proteases and mechanical dissociation yielded cells that also responded to glutamate but not to ATP, and exposure of primary cultures to papain did not abolish Ca2+ responses to several transmitters. The responses of the acutely isolated cells to glutamate but limited or lack of responses to ATP and 5-HT also correspond to what has been seen so far for astrocytes in situ. Thus, the present studies provide direct evidence that some of the receptors seen in primary astrocyte cultures may reflect a response to culture conditions and that, in the context of the relevant information so far available, acutely isolated astrocytes seem to reflect better the in vivo state.     

Distinct regions of bacterial flagellar switch protein FliM interact with FliG, FliN and CheY

The FliG, FliM, and FliN proteins of the bacterial flagellar motor are believed to interact with one another to form the switch complex, which in turn is thought to interact with one of the chemotaxis proteins, CheY. In particular, FliM appears to be an intermediary between CheY and FliG: the current model suggests that CheY, when phosphorylated (CheY-P), binds to FliM and produces a conformational change in FliM that is propagated to FliG. The result of these interactions is to induce clockwise rotation of the flagellar motors and tumbling of the cell. Various genetic and biochemical studies have provided evidence that the switch proteins associate with each other and that CheY-P binds to FliM. Here, we have used affinity blotting to obtain direct evidence of interaction between Salmonella typhimurium FliM and FliN, FliM and FliG, and FliM and CheY-P. We have also examined the ability of various FliM deletion and truncation mutant proteins to bind to FliN, FliG, and CheY-P. From these data, we conclude that distinct regions of the FliM protein bind to each of these other proteins. We propose a model in which the N-terminal region of FliM binds to CheY-P, the middle region of FliM binds to FliG, and the C-terminal region binds to FliN.     

Health care reform in Chile

This is a document presented to the Chilean Academy of Medicine by the Health Minister, the economist Carlos Massad, First of all, he refers to the general context of the reform, that he considers a process and not a breakpoint. Afterwards, he enumerates the change task: a) to generate awareness of the change and to convert health in a State issue; b) to adequate programs to population's new health profile; c) to install new management instruments in the health system; d) to decentralize decisions and to promote the participation of beneficiaries; e) to establish incentives and to flexibilize the Health System and f) to introduce correctives to private health insurance. He believes that Chile must drift to a economical protection system for universal and solidary health events. The additional assurances that people wants to buy, must be delimited.     

The global diversity of protozoa and other small species

In order to compare the prevalence of antibiotic resistance in different geographical areas, it is necessary to ensure agreement between laboratories on the assignment of strains to 'susceptible' and 'resistant' categories. An international quality assessment was performed to investigate the performance of susceptibility testing of Klebsiella spp. Ninety-five strains of klebsiellae were selected from clinical isolates at the London Hospital Medical College (LHMC). These included strains with a diversity of susceptibility profiles to amoxycillin/clavulanate, piperacillin, ceftazidime, cefuroxime, ciprofloxacin, gentamicin and trimethoprim. The strains were sent to 13 participating laboratories in Europe and the USA and laboratories were asked to test the susceptibility of these strains to these antibiotics by their usual methods. They were also asked to provide details of the method used to test susceptibility. Several different standard recommended testing methods were used. Reporting of susceptibilities was generally accurate, but a number of anomalies were noted. Discrepancies of reporting between the LHMC and the participating laboratories was more marked for resistant strains, particularly in the detection of resistance to cefuroxime and ciprofloxacin, as well as the assignment of susceptibility and resistance to piperacillin and amoxycillin/clavulanate. Some discrepancies could be attributed to the use of different breakpoints, leading to differing assignment of susceptibility. Methodological variations including disc content, inoculum and failure to measure and interpret zone sizes consistently also led to anomalies. This quality assessment programme has helped to identify problems in susceptibility testing which should be investigated further.     

Repeated hypergravity: morphologic investigations of pituitary, thyroid, blood and bone marrow in rats

To elicit the mechanism of facilitating the mammals' adaptation to repeated changed gravity influence, the pituitary, thyroid, blood and bone marrow were investigated morphologically in rats exposed to single and repeated hypergravity (2 g) and Coriolis accelerations for 5 days during rotation on centrifuge. No distinct difference in blood and bone marrow cytology was determined after single and repeated exposure to 2 g and the Coriolis accelerations. Compared to single and in contrast to single and repeated exposures to the Coriolis accelerations, a repeated 2 g influence produced some structural changes in somatotropic cells of the pituitary and thyroid parenchyma of the thyroid. These changes were indicative of a significant intensification of synthesis and secretion of somatotropic and thyroid hormones. Elevated functional activity of the somatotropic cells and thyroid parenchyma during repeated exposure to 2 g appears to be a part of mechanism that makes adaptation to repeated hypergravity easier and points to the ability of mammals "to remember" changed gravity. It also advocates for the potentiality of intermittent centrifugation as a means of generating artificial gravity forces in space flight.     

Corticothalamic connections of extrastriate visual areas in rhesus monkeys

Corticothalamic connections of extrastriate visual areas were studied by using the autoradiographic anterograde tracing technique. The results show that the medial extrastriate region above the calcarine sulcus projects mainly to the lateral pulvinar (PL), medial pulvinar (PM), and lateral posterior (LP) nuclei. In addition, the dorsal portion of the medial region has connections to the lateral dorsal (LD) as well as to intralaminar nuclei. The dorsolateral extrastriate region projects strongly to the PL and LP nuclei, to the PM and inferior pulvinar (PI) nuclei, and to the LD and intralaminar nuclei. The lateral extrastriate region above the inferior occipital sulcus (IOS) has strong connections to both the PL and PI nuclei and has minor projections to the PM and oral pulvinar nuclei. The ventrolateral extrastriate region below the IOS projects mainly to the PI nucleus and to the caudal portion of the PL nucleus and has some projections to the PM nucleus. The ventromedial extrastriate region medial to the occipitotemporal sulcus has strong connections with the ventral and medial sectors of the PI nucleus. This region also projects to the caudal portion of the PL nucleus and has minor connections to the LP nucleus. Finally, the annectant gyrus projects to the PL nucleus and to the rostral portion of the PI nucleus and has minor connections to the PM nucleus. Thus, the medial and dorsolateral extrastriate regions are related mainly to the PL and LP nuclei as well as to intralaminar nuclei. In contrast, the ventrolateral and ventromedial regions are connected strongly with the PI nucleus. This connectional organization appears to reflect functional differentiation at the cortical level.     

Rapid Bridge Replacement under Emergency Situation: Case Study

The terrorist attack on September 11, 2001, and subsequent potential threats to the United States transportation systems have presented an urgent need to elevate the security of the transportation infrastructure and to develop emergency response plans to quickly react to the possible consequences of an extreme event. Highway bridges, as critical components of the nation’s transportation network, have been brought to closer attention by government agencies. A research project was conducted to identify strategies and technologies to restore the use of a damaged bridge quickly. One of the tasks associated with the research was to perform several case studies of previous bridge replacements following extreme events. These events include explosion and fire caused by vehicle impact, vessel collision with a bridge, and damage caused by flood and earthquake. By studying the cases, the research team seeks to identify and expand on lessons learned and address which actions did and did not work well given the circumstances of the incident. These lessons have great value to the people who need to develop and implement an emergency response plan.     

The future of psychiatric hospitals in Ontario

The purpose of this paper is to review past and present roles and to speculate on the future of the Ontario provincial psychiatric hospitals (PPHs). Currently, and for the very immediate future only, there are 10 PPHs that are owned and operated by the Ministry of Health of Ontario, each serving a specified population ranging from 250,000 to over 3,000,000. In addition to clinical expertise, provincial psychiatric hospitals contribute greatly to teaching and research. Ontario's mental health reform movement has called for a shift of resources to the community and a downsizing of PPHs by 2003. In response to fiscal pressures, in 1996 provincial legislation was passed to establish the Health Services Restructuring Commission (HSRC) as a stand-alone corporation with powers to restructure and reengineer health services in Ontario. The HSRC has to date recommended the closure of 4 PPHs by 1999 and the integration of theses services into other medical facilities. While a rebalancing of the mental health system does need to take place, the fiscally driven haste to close hospitals has created a crisis atmosphere in PPHs for staff and patients. It is also unlikely that the necessary community resources will be in place to buffer these changes. The new restructuring plans not only set unrealistic timelines, they seem to underestimate the importance PPHs have played in teaching, research and the advancement of clinical treatment and rehabilitation of the severely mentally ill. It may be that, in the long run, service integration and divestment/closure of the PPHs will result in better access to services closer to smaller communities and in the destigmatization of the mentally ill, however, without close evaluative monitoring and appropriate leadership, it could also lead to decreased research, training and quality of care.     

Astigmatism after penetrating keratoplasty. Videokeratoscopic analysis on a series of 60 grafts

Lactoferrin was previously shown to inhibit the adhesion of A. actinomycetemcomitans, P. intermedia and P. nigrescens to human cells. Lactoferrin was also shown to competitively inhibit the binding of these bacteria to the basement membrane protein laminin. The present study aimed to determine the type of interactions inhibited by lactoferrin. Lactoferrin binds to fibroblast monolayers and Matrigel, a reconstituted basement membrane, through ionic interactions. The adhesion of A. actinomycetemcomitans to these substrata was mainly dependent on the ionic strength of the environment. P. intermedia and P. nigrescens also adhere to fibroblasts mainly by ionic interactions, while their adhesion to Matrigel seems to be mediated by specific mechanisms. Lectin-type interactions were not found to be involved in the binding of these bacteria to the substrata. Treatment of either A. actinomycetemcomitans or fibroblasts with lactoferrin decreased the adhesion in a dose-dependent manner, while lactoferrin treatment of Matrigel alone had no adhesion-counteracting effect. Adhesion of P. intermedia and P. nigrescens to Matrigel was not significantly affected by the ionic strength, but the presence of lactoferrin inhibited the adhesion. Lactoferrin bound to Matrigel, P. intermedia and P. nigrescens was rapidly released, while lactoferrin bound to A. actinomycetemcomitans and fibroblasts was retained. These findings indicate that lactoferrin-dependent inhibition of the adhesion of A. actinomycetemcomitans, P. intermedia and P. nigrescens to fibroblasts and Matrigel can involve binding of lactoferrin to both the bacteria and substrata. The decreased adhesion may be due to blocking of both specific adhesin-ligand as well as non-specific charge-dependent interactions.     

Antidromic responses of single units from the spiral ganglion

1. Antidromic responses of single units in the guinea pig spiral ganglion were recorded in response to shocks to the auditory nerve root. The orthodromic responses of these units were also recorded in response to sound. The aim of this study was 1) to classify units according to their response patterns to shocks and to sound and 2) to propose anatomic types that might correlate with these responses. The four classes of units were as follows: type I, olivocochlear (OC), long-latency: locked, and long-latency: jittering. 2. Type I units responded antidromically to shocks with little jitter and short latency. Their responses to sound were also of short latency and had irregular interspike intervals. Some of these units had complex spike waveforms. These units likely correspond to type I primary afferent neurons, the majority population of spiral ganglion cells. 3. One-third of the OC units responded to shocks, with little jitter and intermediate latency (2 ms). OC unit responses to sound were of long latency and had regular interspike intervals. These units likely correspond to efferent neurons that originate in the superior olivary complex of the brain and end on outer hair cells in the cochlea. 4. Long-latency: locked units responded to shocks with little jitter and long latency (4-11 ms). Many of these units had complex spike waveforms and most did not respond to high-level noise bursts. Long-latency: locked units may correspond to type II spiral ganglion neurons. 5. Long-latency: jittering units responded to shocks with a jitter of several milliseconds and long latency. Some of these units responded to sound in a pattern reminiscent of OC units. These units may constitute a subgroup of OC units that respond to shocks via activation of the reflex pathway from the cochlea to the superior olive and back out to the cochlea. 6. Further data were collected on the type I response to shocks. Antidromic spikes lacked the inflections seen on the waveforms that are typically seen on orthodromic spikes. Type I shock responses depended on shock level and duration and were reduced when a click preceded the shock by approximately 2 ms. Several type I characteristics depended on the rate of spontaneous discharge: for units of low and medium spontaneous rates (when compared with units of high rates), the shock thresholds were lower, shock latencies were longer, and the probability of firing repetitive spikes to a single shock was higher.(ABSTRACT TRUNCATED AT 400 WORDS)