16 resultados para Budding brass knuckles
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
A new failure mode is observed in circular brass foils induced by laser beam. The new failure is based on the following experimental facts : (1) the peripheries of the circular brass foils are fixed and the surfaces of the foils are radiated by laser beam ; (2) the laser beam used is considered to be non-Gaussian spatially, actually an approximately uniform distribution limited in a certain size spot ; (3) the pulse on time of laser beam should be 250 μs, i.e. so called long duration pulse laser. The failure process consists of three stages ; i.e. thermal bulging, localized shear deformation and perforation by plugging. The word reverse in reverse bulging and plugging mode means that bulging and plugging occur in the direction of incident laser beam. To study the newly-discovered type of failure quantitatively, analytical solutions for the axisymmetric temperature field and deflection curve are derived. The calculated results show that the newly discovered failure mode is attributed to the spatial structure effect of laser beam indeed.
Resumo:
The peripheries of circular foils of 30 mm in diameter and 0.1 mm thick are fixed while their surfaces are subjected to a long pulsed laser over a central region that may vary from 2 mm to 6 mm in diameter. Failure is observed and classified into three stages; they are referred to as thermal bulging, localized shear deformation, and perforation by plugging. A distinct feature of the failure mode is that bulging and plugging occurred in the direction opposite to the incident laser beam. Such a phenomenon can be expected to occur for a laser intensity threshold value of about 0.61 x 10(6) W/cm(2) beyond which local melting of the material begins to take place.
Resumo:
Recent transcription profiling studies have revealed an unexpectedly large proportion of antisense transcripts in eukaryotic genomes. These antisense genes seem to regulate gene expression by interacting with sense genes. Previous studies have focused on the non-coding antisense genes, but the possible regulatory role of the antisense protein is poorly understood. In this study, we found that a protein encoded by the antisense gene ADF1 acts as a transcription suppressor, regulating the expression of sense gene MDF1 in Saccharomyces cerevisiae. Based on the evolutionary, genetic, cytological and biochemical evidence, we show that the protein-coding sense gene MDF1 most likely originated de novo from a previously non-coding sequence and can significantly suppress the mating efficiency of baker's yeast in rich medium by binding MAT alpha 2 and thus promote vegetative growth. These results shed new light on several important issues, including a new sense-antisense interaction mechanism, the de novo origination of a functional gene, and the regulation of yeast mating pathway.
Resumo:
The brass gudgeon (Coreius heterodon) is a fish of economic importance in the Yangtze River. From a (GATA)(n)-enriched genomic library, 25 microsatellites were developed by employing the fast isolation by AFLP of sequences containing repeats (FIASCO) protocol. Nine loci exhibited polymorphism with two to 12 alleles (mean 3.9 alleles/locus) in a test population, and observed heterozygosity ranged from 0.1111 to 0.9630 (mean 0.4426). Three of the nine loci showed polymorphism in a congeneric species, the largemouth bronze gudgeon Coreius guichenoti. These loci should provide sufficient level of genetic diversity to evaluate the fine-scale population structure of C. heterodon.
Resumo:
A new kind of failure mode is observed in circular brass foils in which their peripheries are fixed and their surfaces are subjected to a long pulsed laser over a central region. The failure is classified into three stages; they are referred to as thermal bulging, localized shear deformation and perforation by plugging. A distinct feature of the failure mode is that bulging and plugging occurred in the direction opposite to the incident laser beam. To study the failure mode, we investigate the non-linear response of heated, non-homogeneous circular plates. Based on the large deflection equations of Berger [J. Appl. Mech. 22 (3), 465-472 (1965)], Ohnabe and Mizuguchi [Int. J. Non-Linear Mech. 28 (4), 365-372 (1993)] and the parabolic shear deformation theory of Bhimaraddi and Stevens [J. Appl. Mech. 51 (1), 195-198 (1984)], we have derived new coupled governing equations of shear deformation and deflection. The new equations are solved, for the plate with a clamped edge, by the Galerkin and iterative methods. The numerical results for the shear deformation distribution are in good agreement with the experimental observation.
Resumo:
A new kind of failure mode is observed in circular brass foils whose peripheries are fixed and whose surfaces are subjected to a long pulsed laser over a central region. The failure is classified into three stages; they are referred to as thermal bulging, localized shear deformation and perforation by plugging. A distinct feature of the failure mode is that bulging and plugging occurred in the direction opposite to the incident laser beam. The failure mode is different from the well-known types of laser induced material damage, such as spallation, melting and/or vaporization.
Resumo:
A new kind of failure induced by long pulsed laser, named as reverse plugging effect (RPE), was experimentally observed in thin foil of brass. The whole failure process can be divided into three stages, namely thermal reverse bulging, shear deformation localization and reverse perforation. In this paper, a description of experimental and theoretical study on this newly discovered phenomenon is presented in detail.
Resumo:
A study of the two-dimensional flow pattern of particles in consolidation process under explosive-implosive shock waves has been performed to further understand the mechanism of shock-wave consolidation of metal powder, in which bunched low-carbon steel wires were used instead of powder. Pressure in the compact ranges from 6 to 30 GPa. Some wires were electroplated with brass, some pickled. By this means, the flow pattern at particle surfaces was observed. The interparticle bonding and microstructure have been investigated systematically for the consolidated specimens by means of optical and electron microscopy, as well as by microhardness. The experimental results presented here are qualitatively consistent with Williamson's numerical simulation result when particle arrangement is close packed, but yield more extensive information. The effect of surface condition of particle on consolidation quality was also studied in order to explore ways of increasing the strength of the compacts. Based on these experiments, a physical model for metal powder shock consolidation has been established.
Resumo:
真空室内金属粒子污染是降低激光薄膜性能的一个重要因素。采用高真空残余气体分析仪,对薄膜沉积过程中的气氛进行分析。发现由黄铜制作的加热灯架在工作时会分解出Zn,在这种条件下沉积薄膜,会使薄膜中掺入金属杂质,导致薄膜激光破坏阈值降低。采用表面分析技术对薄膜的组分进行分析,证实薄膜中锌杂质的存在。激光破坏实验证明,含有锌杂质的薄膜的破坏阈值明显降低。
Resumo:
Chimeric RNAs have been reported in varieties of organisms and are conventionally thought to be produced by trans-splicing of two or more distinct transcripts. Here, we conducted a large-scale search for chimeric RNAs in the budding yeast, fruit fly, mous
Resumo:
Largemouth bronze gudgeon (Coreius guichenoti) is a medium-sized fish endemic from the upper Yangtze River of China and its survival is threatened by the construction of the Three Gorges Dam. This study reports 20 new polymorphic microsatellites from a repeat-enriched genomic library with a mean number allele of 5.2, and observed and expected heterozygosities ranging from 0.035 to 1, and from 0.13 to 0.917, respectively. In a cross-species amplification test, nine of the 37 tested loci were found to be also polymorphic in a congeneric species, brass gudgeon (C. heterodon). In addition, other four loci from common carp (Cyprinus carpio) were also polymorphic in C. guichenoti. Out of these 24 polymorphic microsatellites, only three loci significantly deviated from Hardy-Weinberg equilibrium in the sampled population (P < 0.0025), and all pairwise tests for linkage disequilibrium among loci were nonsignificant after applying sequential Bonferroni correction (P > 0.0026). These novel microsatellites provide sufficient levels of polymorphism for studies on population genetics and conservation in C. guichenoti and its related species.
Resumo:
A pathogenic virus (RGV), isolated from diseased pig frog Rana grylio with lethal syndrome, was investigated with regard to morphogenesis and cellular interactions in EPC cells, a cell Line from fish. Different stages of virus amplification, maturation and assembly were observed at nucleus, cytoplasm and cellular membranes. The matured virus particles, were not only distributed diffusely in nucleus, cytoplasm and cellular surface, but also aggregated as pseudocrystalline arrays in the cytoplasm. Virions were released by budding from the plasma membranes, or following cell lysis. Various types of cell damage, such as small vacuoles, spherical inclusions, and swollen and empty mitochondria, were also found. Some typical characteristics of RGV, such as the symmetrical shape of the virions, replication process involving both nuclear and cytoplasmic phases, budding release from cellular membrane and intracellular membrane, viromatrix and paracrystalline aggregation in cytoplasm, and its acute pathogenic effects, were observed to be similar to that of other iridoviruses. Therefore, the RGV appears to be a member of the Iridoviridae based on these studies. (C) 1999 Elsevier Science B.V. All rights reserved.
Resumo:
In this paper, a pressure-gradient fiber laser hydrophone is demonstrated. Two brass diaphragms are installed at the end of a metal cylinder as sensing elements. A distributed feedback fiber laser, fixed at the center of the two diaphragms, is elongated or shortened due to the acoustic wave. There are two orifices at the middle of the cylinder. So this structure can work as a pressure-gradient microphone in the acoustic field. Furthermore, the hydrostatic pressure is self-compensated and an ultra-thin dimension is achieved. Theoretical analysis is given based on the electro-acoustic theory. Field trials are carried out to test the performance of the hydrophone. A sensitivity of 100 nm MPa-1 has been achieved. Due to the small dimensions, no directivity is found in the test.
Resumo:
依据线粒体上ND2和CO1两个变异较大的基因序列分析了香港地区香港湍蛙7种群、华南湍蛙1种群,以及大陆其他地区华南湍蛙7种群,戴云湍蛙1种群,武夷湍蛙1种群的系统发育关系,进而探讨香港湍蛙的遗传多样性、香港湍蛙特有性、如何确定香港湍蛙最佳保护单元以及这四种湍蛙的物种分类地位。
1. 香港湍蛙保护遗传学研究
香港湍蛙核苷酸传多样性较低,从其遗传多样性信息、单倍型网络分析、中性检验值以及岐点分布结果一致显示香港湍蛙很可能经历了瓶颈后的扩张,种群正在由一个较小的有效种群大小迅速增长, 有足够的时间通过变异用于积累单倍型的多态性, 而对于提高核苷酸多样化而言, 时间尚短(Nei M et al,1975,Avise J C,2000;李明等,2003)。
分子变异分析结果显示香港湍蛙种群间存在较多的基因交流,且系统发育树上各种群间交叉在一起,没有形成与地理单元相关的分支,而从其单倍型网络看,他们源于共同的祖先,是一个单系群,与地理单元间没有形成显著的遗传分化。因此应作为一个进化显著单元(ESU)。结合其与其他湍蛙发育关系及遗传距离以及野外采集信息认为香港湍蛙只在香港地区有分布,属于香港特有种。该物种内遗传多样性较低,又属于世界自然保护联盟红皮书中的近危种,同时也是《野生动物保护条例》中的受保护野生动物,且由于香港城市建设等使得其栖息环境受到威胁,因此在香港特别行政区应该受到重点保护。
从单倍型分布和核苷酸多样性可以看出大榄涌种群和城门种群具有较高的单倍型多样性和核苷酸多样性,应该作为保护的重点区域。
2. 华南湍蛙东、南沿海种群间系统关系
华南湍蛙分布广,各种群存在着丰富的遗传多样性信息且中部种群广西龙胜和湖南张家界种群核苷酸多样性明显高于其他边缘种群华南湍蛙。种群间几乎没有基因交流,且各种群间无共享单倍型,可见已形成了显著的遗传分化。各种群间遗传距离都较远,其中广东南昆山种群以及福建三港种群与其他种群距离最远,因此可以推测其他种群(广东深圳、香港大屿山、广西龙胜和防城以及湖南张家界种群)可能为独立进化的种群。但是否是一新种或一隐存种,还需要结合形态学进行更深入的研究。
本研究中无论从系统关系看还是从遗传距离看,大屿山种群与深圳种群最近,支持陈坚峰等将其定为华南湍蛙,即华南湍蛙新增一个分布点:香港大屿山。
系统树上广西防城种群(支B)与龙胜和湖南种群(支A)形成姐妹群。香港大屿山种群与深圳种群先形成姐妹群(支C),但却没有与其距离很近的广东南岭及南昆山种群(支D)形成姐妹群,可能粤北和粤中的环境及气候较复杂因此与粤南其他种群形成了明显的隔离。同时可以看出华南湍蛙种群遗传分化与地理距离没有显著的相关性。
3. 四种湍蛙间的系统关系
根据线粒体CO1基因建立四种湍蛙间的系统关系及其遗传距离,很清楚地看到,香港湍蛙与戴云湍蛙关系很近,而华南湍蛙则与武夷湍蛙较近。然而,戴云湍蛙同一个种群内部共有两个单倍型DY1和DY2,且两个单倍型间遗传距离大于DY1与香港湍蛙间遗传距离,更远远大于香港湍蛙种群内部的距离,即戴云湍蛙内部两个单倍型间遗传距离达到了种级水平,同样在系统发育树上这两个单倍型与香港湍蛙形成并系。但是,戴云湍蛙种内在形态上差异不显著。因此,其是否属于萌芽物种分化形成(budding speciation)或已经完全分化为两个不同的种值得进一步研究?
与戴云湍蛙香港湍蛙关系类似,从系统树上看华南湍蛙不形成单系,而是分成两个大支,与武夷湍蛙形成并系,且福建和南昆山的华南湍蛙与武夷湍蛙遗传距离远大于武夷湍蛙种内福建种群与浙江种群的遗传距离,达到了种级分化水平。由此,可以推断武夷湍蛙是有效种。系统树上广东深圳、香港大屿山、广西防城和龙胜以及湖南张家界种群与华南湍蛙福建及南昆山各种群间遗传距离已超出了种内各种群间的遗传距离,但是至于这一支是否应为另外一个种,有必要扩大采样,并结合核基因及形态信息进行进一步研究。
MtDNA of ND2 and CO1 gene were used to investigate genetic diversity of Amolops in Hongkong .We collected seven populations of A. hongkongensis,,one population of A.ricketti from Hong Kong and other seven populations of A.ricketti from East and South of Chinese mainland. As well as one population of A. daiyunensis and one population of A.wuyiensis Phylogenetic relationship were analyzed of four species. Discussed whether A.hongkongensis is an endemic species and how can we make the conservation and management decisions.
1. Conservation Genetics of A. hongkongensis
A. hongkongensis has a low nucleotide diversity, the results of genetic diversity, haplotype network, neutrality test and the mismatch distributions indicate that A. hongkongensis experienced a recent expansion after a bottle neck. They had enough time to accumulated haplotype diversity, but it’s too short to have a high nucleotide diversity(Nei M et al,1975,Avise J C,2000;Li et al,2003).
The result of AMOVA reveals that it has much gene exchange among the populations of A. hongkongensis. The clades of the phylogenetic tree were mixed together, no significant genetic differentiation among 8 populations and they share the same ancestor from the network analysis, these indicate that they are monophyly and should be protected as one ESU. Combined with the information of relationships of interspecies, genetic distance and distribution investigate, We conclude that A. hongkongensis is an endemic species of Hong Kong. Considering on the status of low genetic diversity in A.hongkongensis, and this species was listed in the IUCN red list as near threatened, as well as listed in the
Resumo:
维生素(Vitamin)又称维他命,为“万年青”产品,是维持人体生命健康必需的一类低分子有机化合物质。维生素对人体健康的作用人们研究很多, 维生素可以增强人体对感染的抵抗力,降低出生缺陷及降低癌症和心脏病发病率等,一旦缺乏,肌体代谢就会失去平衡,免疫力下降,各种疾病,病毒就会趁虚而入;而维生素对作物影响的研究却很少。目前为止,尚无对用维生素浸种的方法来研究外源维生素是否对小麦种子萌发及幼苗生长起调节作用的报道,且对其在小麦抗逆性方面影响的研究甚少,对盐的胁迫抗性研究尚未有人报道。小麦(Triticum aestivum L.)属于拒盐的淡土性作物。盐害不利于小麦生长,严重影响小麦的产量和品质。本研究采用4 种不同维生素VB1、VC、VB6、VPP,分别对供试小麦品种川育12(红皮)、川育16(白皮)小麦浸种后,在一般自然条件下和逆境(盐胁迫条件)下,进行试验。探讨在正常情况下与在不同盐浓度条件下,各维生素及盐浓度对小麦发芽及幼苗生长的影响,并且比较两种不同皮色的小麦在相同盐胁迫条件下的差异表现,同时研究维生素处理的特异性,且哪种维生素对盐害缓解作用最佳。研究结果表明:在无盐胁迫(自然)条件下,对用4 种不同维生素VB1、VC、VB6、VPP 浸种小麦川育12、川育16 后的种子萌发及幼苗生长(幼苗的根长、根重、苗高、苗鲜重)的研究结果表明:4 种外源维生素浸种均对小麦发芽有调节作用,都能提高其最终发芽率。但是提高幅度有所差异。用VB6 浸种后的小麦提高幅度最多,VC 次之,VPP 提高幅度最小。同时,4 种外源维生素浸种对小麦种子的出芽速度及芽后长势也有一定的影响。VB6、VC 处理的小麦种子出芽速度最快,萌发后长势最好;VB1 出芽速度相对较慢,VPP 最慢,但都大于对照;VB1 处理长势略高于对照,VPP 处理的小麦长势则低于对照。从整体来看,VB6、VC处理促进效应明显, VB1 次之,而VPP 在某些方面无效甚至产生负效应。此外,相同的维生素处理对不同的品种的种子萌发、生长效果也存在差异,各种维生素作用于川育12 的效应均强于对川育16。进一步对幼苗根系TTC 还原力及幼苗叶片中硝酸还原酶活性进行测定、分析。研究发现:并非所有种类的维生素对幼苗根系TTC 还原力及幼苗叶片中硝酸还原酶活性的提高都有帮助。幼苗根系TTC 还原力在不同维生素处理下存在显著差异,而与小麦品种关系甚微。经VB6、VC 处理后,根系TTC 还原力测定值均显著高于对照,VB1 不明显,VPP 则略低于对照。VB6、VC 处理的幼苗叶片中硝酸还原酶的含量大于对照,VB1 与对照相差无几,而VPP 处理的川育12 幼苗叶片中的硝酸还原酶活性比对照CK 略高,而在川育16 中则略比对照CK 有所下降,呈现出抑制效应。综上结果表明:VB6、VC 具有促进种子发芽,幼苗生长及根系生长的作用,是较好的促生长剂;VPP 具有抑制作用,是较好的抑制剂,可进一步研究、开发利用。在盐胁迫条件下,对用4 种不同维生素VB1、VC、VB6、VPP 浸种川育12、川育16 后的种子萌发及幼苗生长(幼苗的根长、根重、苗高、苗鲜重)的研究结果表明:在不同盐浓度胁迫条件下, 各处理的种子萌发及幼苗生长均受到不同程度的抑制。随着盐浓度的增加, 发芽率、发芽指数和活力指数成下降趋势;幼苗的根长、根重、苗高、苗鲜重不断降低。4 种维生素处理间也表现出较大差异。VB6、VC 在每个处理中均保持对盐害的缓解作用,VB6 较VC 更易于促进发芽及幼苗生长。最终发芽率高,根系多、长、重,苗高高、重。而VB1、VPP 则表现出抑制作用。在高盐浓度150mM 时,4 种维生素浸种后的种子,其最终发芽率均不能达到40%,但VB6、VC 处理最终发芽率、苗重、根重均高于对照,VPP 最终发芽率、苗重、根重均低于对照。进一步对幼苗根系TTC 还原力及幼苗叶片中脯氨酸含量进行测定、分析。研究发现:不同盐浓度,不同维生素处理、不同品种间存在差异。随着盐浓度的增加(75mM,100mM,150mM),幼苗根系TTC 还原力活性成下降趋势,幼苗叶片中脯氨酸的积累量成上升趋势。VB6 处理脯氨酸含量增加最为明显,VC 次之,VPP 与对照接近,其变化幅度最小。经VB6、VC 处理后的幼苗根系还原强度,在不同盐浓度下,测定值均显著高于对照,VB1 不明显,VPP 则低于对照,产生负效应。此外,品种间表现不尽相同,相同的维生素处理,相同的盐浓度对不同的品种的种子萌发、生长效果也存在差异, 4 种维生素对川育16 的作用均强于川育12,但其影响趋势是一致的。说明VB6、VC 具有耐(抗)盐性,可以促进种子发芽和幼苗生长,是较好的耐(抗)盐拌种剂。 Vitamin is one kind of necessary low molecular compound for humans tosustain health and life. Lots of Studies have been done on the effectc of the vitaminsfor people. Vitamin can help people improve the body's natural resistance to disease,Drop the rate of birth defects、cacers and the incidence of the heart diseases. Ifpeople have less of them, the metabolism of the organism may throw off balance,immunity may drop off, and catch disease; Though the effects for Vitamin to thecrops are limited. up to now, there’s no one use soking seeds of wheats with vitaminsas a method, to study on how the effects will happen on the wheat seed germinationand seedling growth, and there are only few reserches on antireversion force forwheats ,none for the antireversion force in Sault stress condition.Wheat(Triticum aestivum L.)is sensitive to the salt, so the salt damage will doharm to wheat’s growth, it will have an unfavorable impact on the output and thequality of wheat.On this reaserch, we Soaking CHY12(red)、CHY16 (white) wheat seeds withVitamin C, B1, PP, B6 (50mg/L) as a pretreatment first. Then under two condition: one is in the normal environment the other is in different Salinity, we begin ourexperiments. Then disscuss on if the vitamin and salinity affect the wheat seedgermination and seedling growth, and what is the different between the two of them,the result shows that:Under the normal condition, after soaking seeds with VB1、VC、VB6、Vpp,we study on the their seed germination and the seeding growth(the root length andweights, The seedling heights and weights), it shows that all of those four kinds ofvitamin can adjust the seed germination, but different in The growth rate. VB6 isbest for increase, VC comes second,VPP is the worst. Meanwhile, those four vitaminalso have effect on the speed of the sprouting of the wheat. VB6、Vc can faster theseed germination most, and the seedlings are all doing well; VB1 do little effects onthe budding, Vpp is the worst, but all treatments are better than CK; but in Vi, VB1some what above the CK, while VPP lower than that. On the whole, the acceleratingeffect of VB6、VC are obvious, VB1 takes second place, but VPP in some aspects arenoneffective even have negative effect. Furthermore, different kind of seeds with thesame vitamin may different in seed germination and seedling growth, four vitaminson CHY16 is better than CHY12.More studies on TTC reductive capacity of roots and the activity of nitratereductase in the leaves, the reasult shows not all the vitamin can help the seedlings toimprove the TTC reductive capacity and the activity of nitrate reductase. TTCreductive capacity in different treatments shows significant differences,but notcorrelate to the variety of the wheat. The TTC reductive capacity of VB6、Vctreatments are all higher than CK, VB1 is nearly the same as CK, VPP is a littlelower than CK. Through the study of acivity of nitrate reductase, it shows that,VB6、VC are higher than CK ,VB1 is nearly the same as CK also, VPP is a little higher inthe CK of CHY12 but lower in CHY16. Through all the results above: VB6、Vc helpthe wheat seed germination, seedling growth and the growth of roots, is theperfectable factor of stimulating the growth; Vpp is a inhibition, that’ll be furtherreserch,and well develop and utilize in the future.Under the different Salinity condition, after soaking seeds with VB1、VC、VB6、Vpp,we study on the their seed germination and the seeding growth(the root lengthand weights, The seedling heights and weights), it shows that: under differentsalinity, the seed germination and the seedling growth of any treatment are inhibited.With the increase of the concentration, the germination rate, Vi、Gi all had fallen; theroot length and weight, the seedling heights and weights steadily sank down. There are also have pronounced difference between all treatments with four differentvitamins.VB6、VC in all treatments are alleviative the salt damage, VB6 is easier tocause to put forth buds than VC, and it’s quantitative value is the highest in theultimate germination rate, in root and seedlings’ hight and weight. Though the VPP、VB1 are seems to inhibite its growth. Under the high concentration150mM Nacl, theultimate germination rate in all treatments are below the 40%, but VB6、VC’squantitative values in any experiments are higher than CK,while VPP lower thanCK.Then we study on the TTC reductive capacity of roots and the content of Polinein leaves, the result shows that between the different salinity, different vitamintreatments, different varieties of the wheat have discrepancy.along with theincreasing concentraion of the salinity(75mM,100mM,150mM),TTC reductivecapacity of roots decreases, the accumulation of the content of Poline in leaves havean upward trend. The increase of VB6’s treatment are obviously, VC comessecond,VPP is nearly come up with CK, changes a little. In TTC reductive capacity of roots’s reserch, VB6、VC are higher than CK at any time,VB1 is not palpable,VPP is lower than CK, makes negative affect on wheat. In addition, varieties of thewheats are remain different, no matter it shows promoting or inhibiting, all fourvitamins have moreobvious effects on CHY16 than CHY12, but the tendency of theeffection are the same. It is say that VB6、VC can help wheat to standwith the saultwell, and promot in growth,they are the better reagent to mix with the seed.