非晶La2O3薄膜的阻变存储性能研究

采用脉冲激光技术在Pt/Ti/SiO2/Si衬底上沉积了非晶La2O3薄膜,制作并分析了Pt/La2O3/Pt堆栈层的直流电压与脉冲电压诱导的电阻转变特性。Pt/La2O3/Pt器件单元表现出了稳定的双极性电阻转变,其高低阻态比大于两个数量级。经过大于1.8×106s的读电压,高低阻态的电阻值没有明显的变化,表现出了良好的数据保持能力。通过研究高低阻态的电流电压关系、电阻值与器件面积的关系,揭示了导电细丝的形成和破灭机制是导致Pt/La2O3/Pt器件发生电阻转变现象的主要原因。     

Zidovudine therapy and HIV type 1 mutations in children with symptomatic HIV type 1 infection: effect of switching to didanosine or zidovudine plus didanosine therapy. Italian Multicenter Study Group on HIV Mutations in Children

Type and prevalence of zidovudine (ZDV) resistance mutations in HIV-1-infected children in clinically stable condition and on ZDV monotherapy were analyzed to evaluate the effect of switching to didanosine (ddI) monotherapy or to ZDV plus ddI on the pattern of mutations and on the clinical outcome. Monthly clinical and laboratory controls for HIV-1 infection status were performed; at enrollment and every 4 to 6 months after treatment randomization mutant proviral sequences were evaluated in all the children, whereas viral burden was performed only in a small subgroup of patients randomly selected in each of the three treatment groups. ZDV resistance-associated proviral DNA mutations were defined as low-level resistance (LLR) mutations or medium/high-level resistance (MHLR) mutations; clinical outcome was considered as stable or deteriorating. Results showed that at entry into the study the duration of ZDV therapy was significantly correlated with the presence of mutations, and that the level of resistance given by mutations was associated with the severity both of symptoms and immunodeficiency. After randomization to treatment, in patients with mutations that confer LLR a better clinical outcome with ddI monotherapy than with ZDV plus ddI and ZDV alone was observed in the subsequent 6 months, whereas in patients with mutations that confer MHLR no significant difference among the three treatment groups was found. Data showed also that levels of viral burden at the time of changing therapy are related to clinical outcome if measured by plasma viral load. These results suggest that genotypic resistance assays, together with viral load, may prove useful for rational treatment decisions both at the start of therapy and with failure.     

Physiological and Genetic Characterization of Thiobacillus Ferrooxidans Strains Used in Biohydrometallurgy

Abstract

By using pulsed-field gel electrophoresis, hereditary polymorphism of the chromosomal DNA structure was shown in Thiobacillus ferrooxidans strains isolated from natural and biomining environments and cultivated on different inorganic substrates. Each strain was found to be characterized by a unique restriction pattern of chromosomal DNA reflecting changes in its nucleotide sequence arising in the process of adaptation to specific environmental conditions. Some strains exhibited nonhereditary alterations in chromosomal DNA developing in response to switching to a different oxidation substrate or in the course of adaptation to high concentrations of metal ions. Increased metal resistance of such strains was found to correlate with the number of copies of resistance genes. Amplification of DNA fragments hosting resistance genes disappeared in repeated transfers of strains on the medium lacking the given inducer. With other strains, however, no structural alterations in the chromosomal DNA were detected with the change of the oxidation product. Different mechanisms by which bacterial activity under extreme conditions could be controlled are considered. A significant variation potential of the T. ferrooxidans genome and a wide range of its adaptability under changing environmental conditions suggest that selection of highly efficient natural strains and their adaptation to specific ecological conditions are of major importance for biohydrometallurgy. This puts into question the prospects of constructing recombinant strains for efficient application in biohydromelallurgical processes.     

A crossover study on the glucose metabolism between treatment with olanzapine and risperidone in schizophrenic patients.

Several studies have suggested that risperidone is superior to olanzapine in glucose tolerance; however, there is little information available about the risk of impaired glucose metabolism induced by atypical antipsychotics in the same patients. A 75-g oral glucose tolerance test (OGTT) was performed in 22 mildly obese, diabetes-free, Japanese patients with schizophrenia who received risperidone or olanzapine for at least 2 months. After the OGTT, the medication was switched to another by decreasing the previous dosage gradually over 2 to 8 months after the initiation of the second medicine. After at least 8 weeks of complete switching, the same OGTT procedure was conducted. Fasting insulin concentration and the homeostasis model assessment of insulin resistance (HOMA-IR) during olanzapine treatment were significantly higher compared with risperidone treatment. The area under the concentration-time curves of serum insulin concentrations from 0 to 120 min was different in patients receiving risperidone compared with patients receiving olanzapine; however, there were no differences in the insulinogenic index between the two groups. The present study suggests that olanzapine might impair glucose tolerance to some extent because of an increase in insulin resistance compared with risperidone. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

宝钢电厂1#机组公用400 V P/C母线电源自动切换失败分析

分析了宝钢电厂1^#机组公用400 V P/C母线电源自动切换逻辑，指出了一例1^#机组公用400VP/C母线电源自动切换失败的原因，并提出了对切换逻辑的改进意见。通过改进，提高了母线自动切换的可靠性．同时对母线电源切换的一般原则进行了探讨。     

VO2粉末的制备及其相变性能研究

介绍了一种新颖的、简单易行的二氧化钒粉末制备方法,以VOS04为原料,水解后获得VO(OH)2沉淀,将沉淀清洗、干燥后,对其进行真空热处理,即获得VO2粉末。该方法工艺控制简单,稳定性好,容易掌握。通过对试样的XRD、XPS分析表明,试样为较纯的VO2粉末。试样的相变电、光开关性能测试表明,相变前后试样的电阻值变化了近两个数量级,中红外光学透过率变化了15％。     

基于混沌粒子群——专用遗传算法切换策略的移动机器人路径规划

为了发挥粒子群算法和专用遗传算法的各自优点,提出了一种将二者结合的切换优化策略.该策略前期采用一种基于种群最优个体混沌化的混沌粒子群算法,后期选用专用遗传算法.通过大量仿真实验确定了在迭代代数、种群标准差和最优个体适应度差三种切换指标下各自的最优切换条件.与单一专用遗传算法和单一混沌粒子群算法的仿真对比表明:本文提出的切换优化策略在综合路径长度、平滑性和规划时间三个性能指标后具有一定的优越性.     

Strategies and risks in psychotherapy with bilingual patients: the phenomenon of language independence

The presence of two separate languages, each with its own lexical, syntactic, semantic, and ideational components, can complicate psychotherapy with proficient bilingual patients. If only one language is used in therapy, some aspects of the patients emotional experience may be unavailable to treatment; if both languages are used, the patient may use language switching as a form of resistance to affectively charged material. The authors suggest that monolingual therapists should carefully assess the degree of language independence in bilinguals in order to minimize its impact on therapy. They conclude that study of bilingual patients may provide important insights into the nature of the therapeutic process.     

Combined nasal challenge with diesel exhaust particles and allergen induces In vivo IgE isotype switching

In this study we undertook to provide evidence for local in vivo isotype switching to IgE following nasal challenges. Detection of deleted switch circular DNA (switch circles) by a novel nested polymerase chain reaction-based approach was employed as definitive molecular evidence of Ig isotype switching. Nasal challenge in humans with diesel exhaust particles (DEP) plus ragweed antigen has been shown to enhance local IgE production, stimulate local cytokine production, and markedly increase mucosal IgE antibody to ragweed. Four days after combined intranasal DEP plus ragweed challenge, we detected and characterized clones of deleted switch circular DNA (Sepsilon /Smu) representing switching from mu to epsilon from nasal lavage cells. No switch circular DNA was detected in nasal lavage cells following challenge with DEP alone nor with ragweed allergen alone. These results indicate that the combination of mucosal stimulation with DEP and ragweed allergen is capable of driving in vivo isotype switching to IgE in humans with ragweed allergy. These results are the first direct demonstration of in vivo IgE isotype switching in humans.     

Vitelliform dystrophy in a 64-year-old man

A device suitable for the long-time measurement of relative skin humidity is described. This is a simple circuit with a resistance bridge for lithium chloride sensors connected to a digitally steered logic circuit, which causes dried air to stream intermittently through a measuring chamber placed on the skin in such a way that the relative humidity over the skin is maintained at a constant level. The number of switching time periods is proportional to the relative humidity (secretion performance) of the skin and can be counted, recorded, or directly fed into a digital calculator. The apparatus, including a two-channel version with skin temperature recording, has proved useful in sleep investigations under extreme climatic conditions.     

换向时间对加热炉蓄热室内温度分布的影响

采用高温空气燃烧技术的蓄热式加热炉在钢铁企业应用广泛。蓄热室是蓄热式加热炉的重要组成部件，换向时间是加热炉蓄热室的重要操作参数。为了探讨换向时间对蓄热室内温度分布的影响，以鞍钢连轧作业区1号加热炉为原型，搭建了加热炉蓄热室的试验装置。填充了10层蜂窝陶瓷蓄热体，开展了换向时间对蓄热室温度变化规律、沿蓄热室长度方向温度梯度变化规律影响的试验研究，分析了换向时间对蓄热室传热性能的影响。研究表明，蓄热室的温度随换向时间的延长呈现周期性变化。随换向时间延长，蓄热室平均温度呈现出先降低后升高的趋势，沿蓄热室长度方向的平均温度梯度先增大后减小。试验用加热炉的最佳换向时间为70 s，对应的热回收率、温度效率和综合传热系数分别为81.6%、91.4%和18.3 W/(m2·℃)。     

Cholera toxin and cholera toxin B subunit induce IgA switching through the action of TGF-beta 1

Cholera toxin (CT) and its B subunit (CTB) are potent immunogens and adjuvants that, either alone or linked to protein Ags, can stimulate mucosal immune responses, modulate the induction of oral tolerance, and stimulate IgA isotype switching. The present studies addressed the mechanisms by which CT and CTB promote IgA switching. CT and rCTB, in the presence of IL-2, significantly increased IgA isotype switching at the clonal level in populations of purified and LPS-activated murine surface IgA- spleen B cells, as determined by ELISA, enzyme linked immunospot assays, and limiting dilution analysis. The IgA stimulatory effects of CT and CTB were independent of the A subunit of CT. CTB and CT did not increase the secretory rate of IgA-producing cells or the clonal burst size of IgA clones, and did inhibit B cell growth. Because TGF-beta 1 also inhibits B cell growth and promotes IgA switching, further studies tested whether the activity of CTB and CT on IgA isotype switching was mediated through TGF-beta 1. Anti-TGF-beta Ab and soluble TGF-beta 1 type IIR inhibited CTB- and CT-stimulated IgA isotype switching. Furthermore, increased TGF-beta 1 mRNA levels and bioactive TGF-beta 1, within a range shown to induce IgA isotype switching, were detected in cultures of surface IgA- B cells stimulated with CT or CTB and IL-2. These data indicate that CTB- and CT-stimulated IgA isotype switching are mediated through TGF-beta 1. The finding that CTB up-regulates TGF-beta 1 activity has important implications for understanding the mechanisms by which CTB promotes both IgA mucosal immunity and oral tolerance.     

Should I stay or should I switch? A cost–benefit analysis of voluntary language switching in young and aging bilinguals.

Bilinguals spontaneously switch languages in conversation even though laboratory studies reveal robust cued language switching costs. The authors investigated how voluntary-switching costs might differ when switches are voluntary. Younger (Experiments 1–2) and older (Experiment 3) Spanish–English bilinguals named pictures in 3 conditions: (a) dominant-language only, (b) nondominant-language only, and (c) using “whatever language comes to mind” (in Experiment 2, “using each language about half the time”). Most bilinguals, particularly balanced bilinguals, voluntarily mixed languages even though switching was costly. Unlike with cued switching, voluntary switching sometimes facilitated responses, switch costs were not greater for the dominant language, and age effects on language mixing and switching were limited. This suggests that the freedom to mix languages voluntarily allows unbalanced and older bilinguals to function more like balanced and younger bilinguals. Voluntary switch costs reveal an expanded role for inhibitory control in bilingual language production and imply a mandatory separation by language in bilingual lexical selection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How are words from two languages organized in bilinguals' memory?

30 English-speaking undergraduates, skilled in French, gave continuous word associations to equal numbers of French and English key words. The 1st response could be in either language. Thereafter, in 1 experimental condition S could switch languages at will. In the other 4 conditions, Ss were instructed to switch language at stated rates varying from no switches to switches after each response. Rapid switching produced fewest associates. However, free switching resulted in as good performance as unilingual association, perhaps because Ss chose to switch at their natural word organizational boundaries. The free switching condition revealed that the probability of switching out of either language was lower than the probability of remaining in the current language, indicating stronger intra- than interlanguage associative links. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

谈谈数据通信及其应用前景

数据通信已经渗入到我们的日常办公、生活中，文章从数据通信的构成原理入手，分别介绍了数据通信的电路交换、分组交换、报文交换等几种交换方式以及它们各自的适用范围；对有线数据通信和无线数据通信作了对比和介绍；对数据通信所用到的网络协议作了介绍；对数据通信的现实应用作了说明，并展望未来美好的应用前景。     

Detection and quantitation of human respiratory syncytial virus (RSV) using minigenome cDNA and a Sindbis virus replicon: a prototype assay for negative-strand RNA viruses

African trypanosomes undergo antigenic variation of their variant surface glycoprotein (VSG) coat to avoid being killed by their mammalian hosts. The active VSG gene is located in one of many telomeric expression sites. Replacement of the VSG gene in the active site or switching between expression sites can give rise to a new VSG coat. To study Trypanosoma brucei VSG expression site inactivation rather than VSG gene switching, it is useful to have an in vitro negative-selection system independent of the VSG. We have achieved this aim by using a viral thymidine kinase (TK) gene. Following integration of the TK gene downstream of the 221a VSG expression site promoter, transformant cell lines became sensitive to the nucleoside analog 1-(2-deoxy-2-fluoro-8-D-arabinofuranosyl)-5-iodouracil. These TK trypanosomes were able to revert to resistance at a rate approaching 10(-5) per cell per generation. The majority of revertants expressed a new VSG gene even though there had been no selection against the VSG itself. Analysis of these switched variants showed that some had shut down TK expression via an in situ expression site switch. However, most variants had the complete 221 expression site deleted and another VSG expression site activated. We speculate that a new VSG expression site cannot switch on without inactivation of the old site.     

Phenotypic switching in the human pathogenic fungus Cryptococcus neoformans is associated with changes in virulence and pulmonary inflammatory response in rodents

High-frequency reversible changes in colony morphology were observed in three strains of Cryptococcus neoformans. For one strain (SB4, serotype A), this process produced three colony types: smooth (S), wrinkled (W), and serrated (C). The frequency of switching between colony types varied for the individual colony transitions and was as high as 10(-3). Mice infected with colony type W died faster than those infected with other colony types. The rat inflammatory response to infection with colony types S, W, and C was C > S > W and ranged from intense granulomatous inflammation with caseous necrosis for infection with type C to minimal inflammation for infection with type W. Infection with the various colony types was associated with different antibody responses to cryptococcal proteins in rats. Analysis of cellular characteristics revealed differences between the three colony types. High-frequency changes in colony morphology were also observed in two additional strains of C. neoformans. For one strain (24067A, serotype D) the switching occurred between smooth and wrinkled colonies. For the other strain (J32A, serotype A), the switching occurred between mucoid and nonmucoid colonies. The findings indicate that C. neoformans undergoes phenotypic switching and that this process can affect virulence and host inflammatory and immune responses. Phenotypic switching may play a role in the ability of this fungus to escape host defenses and establish chronic infections.     

Structure and expression of elongation factor Tu from Bacillus stearothermophilus

Over 80% of uropathogenic Escherichia coli express type 1 fimbriae. Expression is phase variable, and regulation of phase switching can differ between isolates. Previously, this was explained by differences in the expression of the fim recombinases, FimB and FimE. Our study of 50 uropathogenic E. coli isolates confirms variation in the regulation of type 1 fimbriae but, in many cases, the variation could be accounted for by sequence changes within and adjacent to the fim switch, rather than by differences in recombinase expression. This was demonstrated by moving the switch from the isolates into an isogenic background and comparing the switching behaviour with that of the original isolate. Isolates could be arranged into groups based on fim switch regulation and sequence similarity. In certain cases, the altered regulation was located to specific basepair changes within the fim switch. Sequence changes were found that had a marked effect on the activity of either FimB or FimE switching, while others affected FimB switching in only one direction. These results emphasize the value of using naturally selected sequence variation to further the understanding of gene regulation.     

CD40 induces resistance to TNF-mediated apoptosis in a fibroblast cell line

CD40, a member of the TNF receptor family, has been characterized as an important T-B cell interaction molecule. In B cells it co-stimulates isotype switching, proliferation, adhesion and is involved in cell death regulation. In addition to B cells, CD40 expression was found on transformed cells and carcinomas. However, little is known about its functions in these cell types. Recent studies show that CD40 mediates the production of pro-inflammatory cytokines in non-hematopoietic cells, inhibits proliferation or induces cell death. In some cell types the apoptotic program triggered by CD40 is only executed when protein synthesis is blocked, suggesting the existence of constitutively expressed resistance proteins. Here we demonstrate that CD40, similar to the 55-kDa TNF receptor (p55TNFR), has a dual role in the regulation of apoptosis in such cells. In the fibroblast cell line SV80 both CD40 and the p55TNFR trigger apoptosis when protein synthesis is blocked with cycloheximide (CHX). Simultaneous activation of both receptors results in markedly enhanced cell death. However, CD40 activation more than 4 h prior to a challenge with TNF/CHX paradoxically conferred resistance to TNF-induced cell death. Protection correlated with NF-kappaB induction and up-regulation of the anti-apoptotic zinc finger protein A20. Overexpression of A20 in turn rendered SV80 cells resistant to TNF cytotoxicity. In conclusion, our data provide evidence that CD40 may regulate cell death in non-hematopoietic cells in a dual fashion: the decision upon apoptosis or survival of a CD40-activated cell seems to depend on its ability to up-regulate resistance factors.