无管换热器的稳态换热特性

对无管换热器中颗粒帘换热单元的稳态换热特性进行了研究,为目前空气预热器的研究提供新的指导方向.通过传热数学模型构建、详细数学计算和定量分析,研究了颗粒质量流量对换热单元以及无管换热器出口温度的影响.研究结果发现,在颗粒帘换热单元中,当颗粒质量流量足够时,冷流体加热后的出口平均温度可无限接近热流体初始温度,冷热流体之间实现深度换热,换热效果明显;在满足颗粒帘空隙率大于0.98的条件下,颗粒质量流量越小,气固颗粒在换热通道中越容易达到换热平衡;由于换热单元中间冷热源-气固颗粒之间的温差小,换热单元的换热效率低,使得由换热单元组成的无管换热器冷热气体之间的整体换热效率较低.     

Variants conferring risk of atrial fibrillation on chromosome 4q25

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in humans and is characterized by chaotic electrical activity of the atria. It affects one in ten individuals over the age of 80 years, causes significant morbidity and is an independent predictor of mortality. Recent studies have provided evidence of a genetic contribution to AF. Mutations in potassium-channel genes have been associated with familial AF but account for only a small fraction of all cases of AF. We have performed a genome-wide association scan, followed by replication studies in three populations of European descent and a Chinese population from Hong Kong and find a strong association between two sequence variants on chromosome 4q25 and AF. Here we show that about 35% of individuals of European descent have at least one of the variants and that the risk of AF increases by 1.72 and 1.39 per copy. The association with the stronger variant is replicated in the Chinese population, where it is carried by 75% of individuals and the risk of AF is increased by 1.42 per copy. A stronger association was observed in individuals with typical atrial flutter. Both variants are adjacent to PITX2, which is known to have a critical function in left-right asymmetry of the heart.     

An estimation of ozone flux in a stratosphere-troposphere exchange event

A new method based on mass fluxes and observed ozone profiles was developed to estimate crosstropopause ozone flux. Using this method, we estimated the cross-tropopause ozone flux in a stratospheric-tropospheric exchange event that occurred over East Asia in March 2001.The result revealed that the ozone flux across the tropopause in this event was an order of magnitude higher than the global and hemispheric average. Compared to the traditional method using a linear relationship between ozone mixing ratio and potential vorticity near the tropopause, the cross-tropopause ozone flux evaluated with ozonesonde data was somewhat higher, although the orders of the two values were the same.     

国内知名企业建设节约型企业的实践及启示

一年前的今天,本刊特制作专题提出了"建设资源节约型社会势在必行"的命题,呼吁创建节约型社会。时隔一年,随着资源之于经济社会发展矛盾的日益凸现,建设节约型社会的呼声一浪高于一浪。3月下旬,江苏省专门召开建设节约型社会的大会。大会提出要从观念创新、制度创新、技术创新诸层面加快推进建设节约型社会。创建节约型社会离不开政府的制度保障,离不开企业的添砖加瓦,更需要全社会的关注和支持。而科技创新可谓是建设节约型社会的关键。面对全球范围内掀起的节能、环保浪潮,对照其他国家进行的一系列科技革新,中国特别是经济发展较快的苏南地区如何在这条道路上走好走稳,本刊将一如既往地予以关注。     

A physical map of the mouse genome

A physical map of a genome is an essential guide for navigation, allowing the location of any gene or other landmark in the chromosomal DNA. We have constructed a physical map of the mouse genome that contains 296 contigs of overlapping bacterial clones and 16,992 unique markers. The mouse contigs were aligned to the human genome sequence on the basis of 51,486 homology matches, thus enabling use of the conserved synteny (correspondence between chromosome blocks) of the two genomes to accelerate construction of the mouse map. The map provides a framework for assembly of whole-genome shotgun sequence data, and a tile path of clones for generation of the reference sequence. Definition of the human-mouse alignment at this level of resolution enables identification of a mouse clone that corresponds to almost any position in the human genome. The human sequence may be used to facilitate construction of other mammalian genome maps using the same strategy.     

Ergonomic Evaluation on Taxi Drivers Compartment

Driving involves long hours of physical work within c onfined compartment. Taxi drivers usually work with prolonged working hours, add itional stress may likely be induced on particular body limbs. Occupational heal th may occur and working efficiency may potentially be affected resulting fr om fatigues, pains or diseases. These problems, however, could be remedied if mo re attention is paid on seating design, the workplace and driving postures adopt ed. Ergonomics design can provide better understanding...     

A family study of endophenotypes for psychosis within an early intervention programme in Hong Kong: Rationale and preliminary findings

The study of endophenotypes may be a viable strategy to tackle the genetic complexity and phenotypic heterogeneity of psychosis, but this research direction is relatively under-developed in China as compared to Western countries. We have recently initiated one of the first family studies of endophenotypes for psychosis in China. Patients entering an established early psychosis intervention service are recruited into this research project for phenotyping, endophenotyping and genotyping. At the endophenotypic...     

碱金属阳离子对手性硼磷酸铜锂化合物LiCu_2[BP_2O_8(OH)_2]晶化的影响

采用硼酸熔融法研究对映体过量的开放骨架硼磷酸铜锂化合物LiCu_2[BP_2O_8(OH)_2]的合成条件,并用Na和K源取代Li源合成该手性化合物.实验结果表明:水和Li~+是生成该手性化合物的关键因素,水过量会使Li~+无法参与晶化,少量的水会促进目标产物形成大单晶;Na~+不能取代Li~+合成该化合物,K~+仅可部分取代Li~+合成该化合物,所得产物均发生对称性破缺.     

Temperature distribution study during the friction stir welding process of Al2024-T3 aluminum alloy

Heat flux characteristics are critical to good quality welding obtained in the important engineering alloy Al2024-T3 by the friction stir welding (FSW) process. In the present study, thermocouples in three different configurations were affixed on the welding samples to measure the temperatures: in the first configuration, four thermocouples were placed at equivalent positions along one side of the welding direction; the second configuration involved two equivalent thermocouple locations on either side of the welding path; while the third configuration had all the thermocouples on one side of the layout but with unequal gaps from the welding line. A three-dimensional, non-linear ANSYS computational model, based on an approach applied to Al2024-T3 for the first time, was used to simulate the welding temperature profiles obtained experimentally. The experimental thermal profiles on the whole were found to be in agreement with those calculated by the ANSYS model. The broad agreement between the two kinds of profiles validates the basis for derivation of the simulation model and provides an approach for the FSW simulation in Al2024-T3 and is potentially more useful than models derived previously.     

成都市商品住宅价格空间分异特征与规律

以成都市商品住宅为研究对象,通过 ＡｒｃＧＩＳ 等方法,研究成都市商品住宅价格空间分异特征和规律。 结果表明:成都 市商品住宅价格总体上呈现出由中心向外围降低的趋势,中心城区主要呈团块状分布,近郊区主要呈放射状分布,远郊区主 要呈星岛状分布;低房价区段在西部—北部—东部地区呈现 ２ 条“半环状”分布;中低房价区段呈“环状＋放射状”分布。 在中 心城区形成了环状分布,在近郊区及远郊区形成了自中心城区向外延伸的放射状分布特征;中房价区段在中心城区分布相对 集中并呈团块状分布,在近郊区呈放射状分布,远郊区呈零星分布特征;中高房价区段在中心城区、高新区、天府新区呈组团 状分布,在近郊区呈放射状分布,远郊区呈零星分布的特征;高房价区段自中心城区沿天府大道向南延伸至天府新区,形成了 南—北走向的峰值带。