温度对含V和Ti生铁高温氧化性能的影响

摘要：为研究温度对含V、Ti生铁高温氧化性能的影响规律，采用静态不连续增重法绘制了氧化动力学曲线，并结合SEM-EDS和XRD检测手段，分析了含V、Ti生铁的高温氧化机制。结果表明，含V、Ti生铁的氧化增重与时间呈线性关系，900℃后氧化速率会迅速上升；高温下生成的氧化层为双层结构，表层主要氧化物为Fe2O3，外氧化层为连续的Fe2O3和TiO2的混合氧化物，内氧化层主要由V2O3组成；Ti在氧化层中扩散速率较快，随着氧化层变厚，TiO2逐渐从片层状氧化物中富集成团状。当氧化温度高于900℃后，TiO2能够破坏表层氧化物的连续性，导致含V、Ti生铁氧化层疏松脱落。     

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。     

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。     

TiB2-HfC陶瓷的高温抗氧化性能

为了研究TiB₂-HfC陶瓷的高温抗氧化性能, 分析了TiB₂-HfC陶瓷在1100 ℃下分别氧化1、4、7、10 h后的氧化行为; 根据材料氧化后的微观结构, 对陶瓷氧化层进行了划分, 将其分为外氧化层、次氧化层及过渡层。实验结果表明: 外氧化层的氧化物为TiO₂、B₂O₃、HfO₂、NiO和CoO; 随着氧化时间的延长, 材料发生了严重氧化, 氧化层逐渐变厚, 材料保有的抗弯强度逐渐减小, 材料的氧化增重与氧化时间呈抛物线规律; 氧化1h后, 材料表面形成了约为12 μm的致密氧化层, 此时材料具有较好的抗氧化性能, 且仍保有较高的抗弯强度, 其值为823.6 MPa。     

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.     

Multicenter trial of Enterococcus antibiotic susceptibility

Antibiotic susceptibility of 446 Enterococcus isolates from 9 medical centres of Moscow and St. Petersburg was tested. Among the isolates 386 belonged to E.faecalis, 48 to E.faecium and 12 to the other species. All the isolates were susceptible to vancomycin. As for E.faecalis 84 and 85 per cent of the isolates were susceptible to ampicillin and ampicillin/sulbactam respectively (no production of beta-lactamases), the frequency of high resistance to aminoglycosides amounted to 44 per cent with respect to streptomycin and to 25 per cent with respect to gentamicin, 75 per cent of the isolates was susceptible to ciprofloxacin. As for E.faecium and the rare species of Enterococcus more than 70 per cent of the isolates was resistant to ampicillin and ampicillin/sulbactam, the frequency of high resistance to aminoglycosides exceeded 60 per cent, 17 and 25 per cent of the isolates were susceptible to ciprofloxacin.     

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.     

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)     

Interaction of estradiol, progesterone and corticosterone on uterine connective tissue degrading enzymes

The impact of ovarian hormones and corticosterone acetate on uterine connective tissue degrading enzymes were studied in mature albino rats. Ovariectomy resulted in a significant increase in the activities of alpha- and beta-galactosidases and glucosidases in the uterus. Administration of estradiol to ovariectomized rats brought back the activities of alpha-galactosidase and alpha-glucosidase to normalcy. While beta-galactosidase and beta-glucosidase were significantly decreased. Administration of progesterone to ovariectomized rats resulted in the increase of alpha- and beta-galactosidases and glucosidases. Administration of corticosterone to ovariectomized rats produced a further increase in alpha- and beta-galactosidases and glucosidases in the uterus. Adrenalectomy in ovary intact rats produced a decrease in alpha-galactosidase however, beta-glucosidase was significantly increased. Administration of corticosterone to ovary intact rats significantly increased the activities of alpha- and beta-galactosidases, while alpha- and beta-glucosidases were found to be decreased. Ovariectomy resulted in a significant increase in the activities of cathepsin-D and cathepsin-E. Administration of estradiol to ovariectomized rats brought back the activity of cathepsin-D to normalcy, whereas cathepsin-E was significantly increased. Administration of progesterone as well as estradiol to ovariectomized rats significantly increased the levels of cathepsin-E, however, cathepsin-D was brought back to normalcy. Administration of corticosterone to ovariectomized rats as well as ovariectomy + adrenalectomy significantly increased the activity of cathepsin-D and cathepsin-E. Adrenalectomy significantly decreased the activity of cathepsin-D, while administration of corticosterone increased the cathepsin-D and cathepsin-E in the uterus. Therefore, these results suggest that estradiol is a potent ovarian steroid protecting the extra cellular matrix components. The effect of progesterone appears to modulate and act hand in hand with estradiol. Corticosterone appears to have an opposite effect to that of estradiol.     

Allergic reactions to betalactams: studies in a group of patients allergic to penicillin and evaluation of cross-reactivity with cephalosporin

A group of 34 penicillin-allergic patients was studied to determine skin test reactivity to the different penicillins involved in inducing the allergic reaction and the cross-reactivity with side-chain-related and side-chain-unrelated cephalosporins. All the subjects selected for the study had to be skin test positive to at least one of the following determinants: benzyl-penicilloyl-polylysine (BPO-PLL), minor-determinant mixture (MDM), amoxicillin (AX), or ampicillin (AMP), or to possess in vitro IgE to the following conjugates: benzyl-penicilloyl-human-serum albumin (BPO-HSA), ampicilloyl-human-serum albumin (AMP-HSA), and amoxicilloyl-human-serum albumin (AX-HSA). Cephalexin (CE) and ceftazidime (CEF) were used to assess cross-reactivity. If skin tests to any of these compounds were positive, the patient was considered to be allergic; if negative, a challenge test was performed. Sixteen patients (47%) were skin test positive to BPO and/or MDM, and nine (26%) exclusively to AX and/or AMP. In three cases (8%), the RAST was positive although the skin test was negative; one to BPO-HSA and two to AX-HSA and AMP-HSA. Six patients (17%) needed to be challenged with the penicillin involved to establish the diagnosis. In five patients (14%), the skin tests were positive to CE and in none to CEF. In all the others, the skin tests were negative to both cephalosporins, and the patients tolerated the drugs when challenged. These results indicate the relevance of side-chain-specific minor determinants in betalactams allergy and provide support for the role of this chemical structure in the evaluation of cross-reactivity between penicillins and cephalosporins.     

Developmental issues in child health psychology.

Illustrates a developmental perspective in child health psychology by discussing research relating motor, cognitive, and psychosocial development to exposure to health hazards, to an understanding of behavior–health relationships, to the assumption of personal responsibility for health, and to behavioral and emotional responses to illness and injury. It is suggested that changes in motor skills and abilities affect the child's ability to interact with his/her physical environment and influence the likelihood of falling victim to health hazards. Cognitive and intellectual development is crucial to the child's ability to understand the relationships between behavior and health and illness and to make decisions about his/her health behavior. Psychosocial development is critical to the issue of individual responsibility in health behavior. It is proposed that a developmental perspective be added as a 4th dimension to the commonly employed 3-dimensional conceptualization of health psychology. (100 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)