铁氮共掺杂纳米TiO2的制备及其光催化性能的研究

以钛酸四丁酯为原料,采用溶胶-凝胶法制备了TiO2和不同含铁量的铁氮共掺TiO2,并用荧光光谱对其进行表征;研究了紫外光照射下对孔雀石绿的降解,对比考察了不同掺杂的TiO2、不同比例掺铁量的共掺杂TiO2,以及催化剂的用量和不同浓度下的降解;结果表明:当Fe/Ti的质量分数为0.9%,用量在2 g/L时,孔雀石绿的降解效果最好,孔雀石绿的最佳降解质量浓度为50 mg/L,150 min的降解率可达98.96%;而且荧光表征显示:样品的荧光强度越小,催化效果越好.     

基于论域空间降维的机电产品故障诊断

提出了一种基于论域空间降维的机电产品故障诊断方法。通过对粗糙集论域空间进行降维，降低了计算复杂性，在此基础上通过属性约简和值约简，导出了清晰简明的诊断决策规则。运用该方法对镇流器自动化生产线上的故障诊断进行研究，实例分析表明，这种新方法提高了故障诊断的能力，对进行在线故障诊断具有实际应用价值。     

A second class of chemosensory receptors in the olfactory epithelium

The mammalian olfactory system detects chemicals sensed as odours as well as social cues that stimulate innate responses. Odorants are detected in the nasal olfactory epithelium by the odorant receptor family, whose approximately 1,000 members allow the discrimination of a myriad of odorants. Here we report the discovery of a second family of receptors in the mouse olfactory epithelium. Genes encoding these receptors, called 'trace amine-associated receptors' (TAARs), are present in human, mouse and fish. Like odorant receptors, individual mouse TAARs are expressed in unique subsets of neurons dispersed in the epithelium. Notably, at least three mouse TAARs recognize volatile amines found in urine: one detects a compound linked to stress, whereas the other two detect compounds enriched in male versus female urine-one of which is reportedly a pheromone. The evolutionary conservation of the TAAR family suggests a chemosensory function distinct from odorant receptors. Ligands identified for TAARs thus far suggest a function associated with the detection of social cues.     

The Collaborative Cross, a community resource for the genetic analysis of complex traits

The goal of the Complex Trait Consortium is to promote the development of resources that can be used to understand, treat and ultimately prevent pervasive human diseases. Existing and proposed mouse resources that are optimized to study the actions of isolated genetic loci on a fixed background are less effective for studying intact polygenic networks and interactions among genes, environments, pathogens and other factors. The Collaborative Cross will provide a common reference panel specifically designed for the integrative analysis of complex systems and will change the way we approach human health and disease.     

The genome of Cryptosporidium hominis

Cryptosporidium species cause acute gastroenteritis and diarrhoea worldwide. They are members of the Apicomplexa--protozoan pathogens that invade host cells by using a specialized apical complex and are usually transmitted by an invertebrate vector or intermediate host. In contrast to other Apicomplexans, Cryptosporidium is transmitted by ingestion of oocysts and completes its life cycle in a single host. No therapy is available, and control focuses on eliminating oocysts in water supplies. Two species, C. hominis and C. parvum, which differ in host range, genotype and pathogenicity, are most relevant to humans. C. hominis is restricted to humans, whereas C. parvum also infects other mammals. Here we describe the eight-chromosome approximately 9.2-million-base genome of C. hominis. The complement of C. hominis protein-coding genes shows a striking concordance with the requirements imposed by the environmental niches the parasite inhabits. Energy metabolism is largely from glycolysis. Both aerobic and anaerobic metabolisms are available, the former requiring an alternative electron transport system in a simplified mitochondrion. Biosynthesis capabilities are limited, explaining an extensive array of transporters. Evidence of an apicoplast is absent, but genes associated with apical complex organelles are present. C. hominis and C. parvum exhibit very similar gene complements, and phenotypic differences between these parasites must be due to subtle sequence divergence.     

Experimental realization of a one-atom laser in the regime of strong coupling

Conventional lasers (from table-top systems to microscopic devices) typically operate in the so-called weak-coupling regime, involving large numbers of atoms and photons; individual quanta have a negligible impact on the system dynamics. However, this is no longer the case when the system approaches the regime of strong coupling for which the number of atoms and photons can become quite small. Indeed, the lasing properties of a single atom in a resonant cavity have been extensively investigated theoretically. Here we report the experimental realization of a one-atom laser operated in the regime of strong coupling. We exploit recent advances in cavity quantum electrodynamics that allow one atom to be isolated in an optical cavity in a regime for which one photon is sufficient to saturate the atomic transition. The observed characteristics of the atom-cavity system are qualitatively different from those of the familiar many-atom case. Specifically, our measurements of the intracavity photon number versus pump intensity indicate that there is no threshold for lasing, and we infer that the output flux from the cavity mode exceeds that from atomic fluorescence by more than tenfold. Observations of the second-order intensity correlation function demonstrate that our one-atom laser generates manifestly quantum (nonclassical) light, typified by photon anti-bunching and sub-poissonian photon statistics.     

Antibody and HIV-1 gp120 recognition of CD4 undermines the concept of mimicry between antibodies and receptors.

It has been proposed that antibodies can mimic the binding of a receptor to its ligand and that anti-idiotype antibodies raised against such antibodies can be used to identify the receptor. A large number of antibodies have been raised against CD4, the receptor on T cells for the envelope glycoprotein gp120 of the human immunodeficiency virus, and the site at which gp120 binds to CD4 has been delineated. It has therefore become possible to contrast the fine specificities of a natural ligand (gp120) and antibodies that interact with the receptor at the same site. Here we report that out of a panel of 225 anti-CD4 antibodies, only one showed fine binding specificity that was broadly like that of gp120, but the evidence was against this being an exact mimic. Thus the data indicate that the production of antibody mimics will occur very rarely or not at all and that the anti-idiotype approach is unlikely to be useful. This contention is supported by a review of the results of attempts to use this approach. Taking strict criteria for success, there is no example for which the anti-idiotype approach has led to the discovery of a previously undescribed receptor or other protein of interest.     

Prolonged suppression of ecosystem carbon dioxide uptake after an anomalously warm year

Terrestrial ecosystems control carbon dioxide fluxes to and from the atmosphere through photosynthesis and respiration, a balance between net primary productivity and heterotrophic respiration, that determines whether an ecosystem is sequestering carbon or releasing it to the atmosphere. Global and site-specific data sets have demonstrated that climate and climate variability influence biogeochemical processes that determine net ecosystem carbon dioxide exchange (NEE) at multiple timescales. Experimental data necessary to quantify impacts of a single climate variable, such as temperature anomalies, on NEE and carbon sequestration of ecosystems at interannual timescales have been lacking. This derives from an inability of field studies to avoid the confounding effects of natural intra-annual and interannual variability in temperature and precipitation. Here we present results from a four-year study using replicate 12,000-kg intact tallgrass prairie monoliths located in four 184-m(3) enclosed lysimeters. We exposed 6 of 12 monoliths to an anomalously warm year in the second year of the study and continuously quantified rates of ecosystem processes, including NEE. We find that warming decreases NEE in both the extreme year and the following year by inducing drought that suppresses net primary productivity in the extreme year and by stimulating heterotrophic respiration of soil biota in the subsequent year. Our data indicate that two years are required for NEE in the previously warmed experimental ecosystems to recover to levels measured in the control ecosystems. This time lag caused net ecosystem carbon sequestration in previously warmed ecosystems to be decreased threefold over the study period, compared with control ecosystems. Our findings suggest that more frequent anomalously warm years, a possible consequence of increasing anthropogenic carbon dioxide levels, may lead to a sustained decrease in carbon dioxide uptake by terrestrial ecosystems.     

基于CAN总线的汽车冷却液罐试验台测控系统设计

根据汽车冷却液储液罐试验台测控系统的要求,设计了基于CAN总线的分布式测控系统.采用具有CAN总线接口的输入/输出模块实现了现场测控,监控室的工业控制计算机通过CAN适配卡与各模块进行通信,详细介绍了测控软件的设计方法.     

基于AutoCAD Mechanical的货架横梁设计

介绍了Autodesk AutoCAD Mechanical软件的转动惯量和挠度线的计算功能,并以实例介绍在货架横梁设计中的应用,对横梁的截面进行惯性矩的计算,并用惯性矩的计算结果计算挠度线和安全系数,提高了计算精度并加快了设计进度．