嵌套重叠网格的构造策略及其隐式切割

高质量网格的设计与生成是复杂流动CFD精确计算最主要的决定性因素之一．本文通过采用新颖的多层嵌套重叠网格策略、可靠的重叠网格切割准则、快速的多级网格切割方法和高效的隐式切割技术,发展了一种多层多块隐式嵌套重叠网格技术以及相应的多级多重网格流动计算方法．在生成嵌套重叠网格时,只需要初始网格和边界条件,而无需人工干预,实现了嵌套重叠网格的自动切割．对某级网格进行多重网格流动计算时,仅考虑该级网格的嵌套重叠切割处理,而忽略低级粗网格的网格切割影响,有效提高了流动的计算效率．两个典型的复杂流动算例的计算结果与实验值吻合良好,证明了本文方法的可靠性．     

Characterization of major histocompatibility complex DRA and DRB genes of the forest musk deer (Moschus berezovskii)

The forest musk deer(Moschus berezovskii) is one of the most endangered species in China.Over the past decades,extensive hunting and poaching have pushed the forest musk deer to the edge of extinction,and conservation biologists are presently pursuing scientific management plans to rescue this species.The major histocompatibility complex(MHC),a cluster of genes responsible for antigen presentation,is a highly polymorphic genomic region in vertebrates that has become a popular functional marker system for studying adaptive variation.In this study,we developed locus-specific genotyping primers for exon 2 fragments of one DRA gene and one DRB locus of the forest musk deer using a suite of comprehensive methods that included universal primer amplification,genome walking,single-strand conformation polymorphism(SSCP),heteroduplex(HD) profiling,and sequence analysis.Each forest musk deer showed no more than two sequences per locus,confirming the specificity of our primers.Genotyping with these primers allowed us to identify two DRA alleles and six DRB alleles in a captive breeding population of the Sichuan Musk Deer Breeding Institution.For the DRA locus,we found a slightly higher observed heterozygosity(N O =0.154) than expected(N E =0.143).In contrast,the DRB locus showed a significant heterozygote deficiency(N O =0.508;N E =0.761;P<0.05),which was probably due to inbreeding in the captive population.An obvious excess of nonsynonymous substitutions over synonymous was observed at the antigen-binding positions of the DRA and DRB loci,showing the presence of positive selection in the forest musk deer DR genes.Finally,generation of phylogenetic trees for the DRA and DRB sequences of the forest musk deer and other ruminants revealed that the DRA and DRB loci identified in this study had homologous relationships with the known ruminant DRA and DRB genes.Based on this analysis,and to facilitate future studies,we named these novel loci Mobe-DRA and Mobe-DRB3.     

Assessment of genetic diversity in the forest musk deer （Moschus berezovskii） using microsatellite and AFLP markers

Microsatellite genotyping and amplified fragment length polymorphism (AFLP) techniques are often utilized in studies of conservation genetics of endangered animals. To select a more effective marker system for conserving the endangered forest musk deer, we used microsatellite and AFLP markers to estimate levels of genetic diversity of two populations, the pure mother Jinfengshan (JFS) group and the offspring Baisha (BS) group with introduction of new blood. It was expected that JFS would pos- sess significa...     

Flame propagation characteristics and flame structures of zirconium particle cloud in a small-scale chamber

Flame propagating through zirconium particle cloud in a small-scale vertical rectangle chamber was investigated experimentally. In the experiments, the zirconium quoted 99% purity was used and the diameter of particles was distributed 1–22 μm. The zirconium dust was dispersed into the chamber by air flow and ignited by an electrode spark. A high-speed video camera was used to record the images of the propagating flame. Micro-thermocouples, schlieren optical system and microscopic lens were used to obtain temperature profiles and flame structure, respectively. Based on the experimental results, flame propagation characteristics and flame structure of zirconium particle cloud were analyzed. The propagation velocity of the flame is quite slow in the initial 14 ms and then accelerates to maximum value. Subsequently, the propagation velocity of the flame almost keeps constant. The combustion zone width of zirconium particle cloud is 5–6 mm. Smaller particles burn mainly at the leading edge of combustion zone in the width of 1.4 mm followed by larger particles burning 1.4–6 mm behind the leading edge of the combustion zone. Gas phase flame is not seen in zirconium particle cloud and the combustion time of single zirconium particle is 1–5 ms, which depends on its original size. The preheated zone is 7–8 mm thickness ahead of the combustion zone and intensive chemical reaction takes place at 490 K. The maximum flame temperature increases at lower concentrations, reaches the maximum value, and then decreases slightly at higher concentrations.     

Isolation and characterization of class I MHC genes in the giant panda (Ailuropoda melanoleuca)

Artificial breeding is an important project to protect,recover and reintroduce endangered species.Knowledge of the population’s genetic diversity at functional loci is important for the establishment of effective captive breeding programs.The major histocompatibility complex(MHC) genes are ideal candidate genetic markers to inform planned breeding,due to their high levels of polymorphism and importance in the main immune coding region of the vertebrate genome.In this study,we constructed BAC-based contigs and isolated six functional MHC class Ⅰ genes from the giant panda(Ailuropoda melanoleuca),which we designated Aime-C,Aime-F,Aime-I,Aime-K,Aime-L and Aime-1906.Analyses of the tissue expression patterns and full-length cDNA sequences of these class I genes revealed that Aime-C,-F,-I and-L could be considered classical class Ⅰ loci,due to their extensive expression patterns and normal exonic structures.In contrast,Aime-K and-1906 appeared to be nonclassical genes based on their tissue-specific expression patterns and the presence of an abnormal exon 7 in both genes.We established techniques for genotyping exons 2 and 3 of the classical loci using locus-specific single strand conformation polymorphism(SSCP) and sequence analysis.In the Chengdu captive population,we identified one monomorphic locus(Aime-F) and three polymorphic loci with different numbers of alleles(4/4/4 exon 2 alleles at Aime-C/I/L and 6/5/5 exon 3 alleles at Aime-C/I/L).The distributions of the Aime-C,-I and-L alleles among members of different families were in good agreement with the known pedigree relationships,suggesting that the genotyping results are reliable.Therefore,the MHC-I genotyping techniques established in this study may provide a powerful tool for the future design of scientific breeding or release/reintroduction programs.     

酶催化合成维生素C脂肪酸酯的反应条件优化

以维生素C(Vc)和若干种脂肪酸为底物,采用自制假丝酵母Candida sp. 99-125固定化脂肪酶,催化合成维生素C脂肪酸酯。结果表明,在该酯化反应中,油酸为最佳脂肪酸底物,丙酮为最佳反应介质。同时研究了各反应因素对Vc转化率的影响,优化后的反应条件为：当Vc浓度为006mol/L时,温度40℃,固定化酶量1.5g,油酸与Vc物质的量比为5∶1,反应时间48h,分子筛添加量0.5g,底物Vc分4次流加,Vc转化率可达91%,批次实验表明该固定化酶在重复使用10次后仍具较高活力.     

Preliminary lidar observations of Na meteor trails at Wuhan (30.5°N, 114.4°E), China

Na lidar measurements of atom meteor trails with an integration period of 3.2 s were conducted at Wuhan (30.5°N, 114.4°E), China. A total of 125 Na meteor trail events were registered from 166 hours (16 nights) of lidar data. These Na trails show peak densities ranging from 4040 to 39170 cm⁻³ with a mean of 16430 cm⁻³, while their occurrence altitudes vary from 77.2 to 111.6 km with a distribution centroid at 92.6 km. The upper edge of the Na trail altitude distribution resembles that of the altitude profile of the simultaneously observed mean Na layer. In particular, the trail altitude histogram maximum occurs around the mean Na layer peak. This is consistent with early lidar observations of K and Fe trails, which shows that meteoroids entering the atmosphere tend to yield more atom meteor trails detectable by ground-based lidars around the peak of the regular metal layers than elsewhere. It was found that the formation of the Nas layers was usually accompanied by a bunch of Na meteor trails, and that they occurred near the altitude of the Nas layer peak.