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Search Results: 1 - 10 of 104327 matches for " Huayu Zhang "
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An Efficient and Concise Algorithm for Convex Quadratic Programming and Its Application to Markowitz’s Portfolio Selection Model  [PDF]
Zhongzhen Zhang, Huayu Zhang
Technology and Investment (TI) , 2011, DOI: 10.4236/ti.2011.24024
Abstract: This paper presents a pivoting-based method for solving convex quadratic programming and then shows how to use it together with a parameter technique to solve mean-variance portfolio selection problems.
Characterization of MASDs of surface soils in north China and its influence on estimating dust emission
Fanmin Mei,Xiaoye Zhang,Huayu Lu,Zhenxing Shen,Yaqiang Wang
Chinese Science Bulletin , 2004, DOI: 10.1007/BF03185784
Abstract: The micro-aggregated size distribution (MASD) of surface soil is an important parameter for modelling dust emission. However, there is no dataset of MASDs of all surface soil types in north China. The MASDs are here presented, measured by dry sieving, for typical surface soil samples, including sandy soil, gravelly sand soil, gravelly loam soil, loam soil and silt loam soil, collected from sandy deserts, Gobi deserts, oases, farmlands in steppe regions and steppe areas in north China. The MASDs of various surface soil types exhibit a combination of several log-normal distributions of five separated sizes with mean mass median diameters (MMDs) of 90, 210, 390, 600 and 980 μm, respectively, and mean standard deviations (SDs) of 1.25, 1.40, 1.25, 1.35 and 1.25 respectively. The log-normal distributions correspond to very fine sand, fine sand, medium sand, coarse sand and very coarse sand population. On the basis of characterization of the retrieved MASDs of various surface soil types in north China, dust emission fluxes are modelled by a dust production model (DPM model). It is shown that dust emission has been significantly influenced by MASDs. Fine sand and very fine sand are always associated with the highest dust emission fluxes. Emission fluxes of the medium sand, gravelly sand soil, gravelly loam soil and loam soil are lower than those of very fine sand and fine sand, but larger than those of the coarse sand. The differences in dust emission fluxes vary among the different soil types from 101 to 103 (μg · m 2 · s 1. Dust emission fluxes from sandy deserts and farmlands covered with sand sheets in north China rang from 101 to 104 μg · m 2 · s 1 while those from Gobi deserts, farmlands and steppes with gravelly desertification range from 101 to 102 μm · m 2 · s 1. The modelled results indicate that deserts and farmlands with sand are the major dust sources in north China.
Glucose production from hydrolysis of cellulose over a novel silica catalyst under hydrothermal conditions
Huayu Wang,Changbin Zhang,Hong He,Lian Wang,
Huayu Wang
,Changbin Zhang,Hong He,Lian Wang

环境科学学报(英文版) , 2012,
Abstract: A novel silica catalyst was synthesized by evaporation-induced self-assembly (EISA) method and tested for the catalytic selective hydrolysis of cellulose to glucose. This silica catalyst exhibited a higher catalytic activity than other oxides prepared by the same method, such as ZrO2, TiO2, and Al2O3. Using silica as a catalyst, cellulose was selectively hydrolyzed into glucose with a glucose yield as high as 50% under hydrothermal conditions without hydrogen gas. The silica catalyst was characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results of temperature-programmed desorption of ammonia (NH3-TPD) and textural properties indicated that the synergistic effect between strong acidity and a suitable pore diameter of the silica catalyst may be responsible for its high activity. In addition, the catalyst was recyclable and showed excellent stability during the recycle catalytic runs.
Structure and Mechanical Performance of Nitrogen Doped Diamond-like Carbon Films
Huayu ZHANG,Liangxue LIU,Yulei WANG,Hongtao MA,Fanxin LIU,
Huayu
,ZHANG,Liang-xue,LIU,Yulei,WANG,Hongtao,MA,Fanxin,LIU

材料科学技术学报 , 2007,
Abstract: Nitrogen doped diamond-like carbon (DLC:N) films were prepared by electron cyclotron resonance chemical vapor deposition (ECR-CVD) on polycrystalline Si chips. Film thickness is about 50 nm. Auger electron spectroscopy (AES) was used to evaluate nitrogen content, and increasing N2 flow improved N content from 0 to 7.6%. Raman and X-ray photoelectron spectroscopy (XPS) analysis results reveal N-sp3C and N-sp2C structure. With increasing the N2 flow, sp3C decreases from 73.74% down to 42.66%, and so does N-sp3C from 68.04% down to 20.23%. The hardness decreases from 29.18 GPa down to 19.74 GPa, and the Young's modulus from 193.03 GPa down to 144.52 GPa.
Preparation, Characterization, and Application of Magnetic Fe-SBA-15 Mesoporous Silica Molecular Sieves
Huayu Huang,Yongsheng Ji,Zhenfeng Qiao,Chuande Zhao,Jianguo He,Haixia Zhang
Journal of Analytical Methods in Chemistry , 2010, DOI: 10.1155/2010/323509
Abstract: Magnetic Fe-SBA-15 mesoporous silica molecular sieves were prepared, characterized, and used for magnetic separation. Wet impregnation, drying, and calcination steps led to iron inclusion within the mesopores. Iron oxide was reduced to the metal form with hydrogen, and the magnetic Fe-SBA-15 was obtained. Fourier-transform infrared spectroscopy confirmed the preparation process from the oxide to metal forms. The structure of magnetic materials was confirmed by M?ssbauer spectra. Powder X-ray diffraction data indicated that the structure of Fe-SBA-15 retained the host SBA-15 structure. Brunauer-Emmett-Teller analysis revealed a decrease in surface area and pore size, indicating Fe-SBA-15 coating on the inner surfaces. Scanning electron micrographs confirmed the decrease in size for modified SBA-15 particles. From scanning electron micrographs, it was found that the size of the modified SBA-15 particles decreased. Transmission electron micrographs also confirmed that modified SBA-15 retained the structure of the parent SBA-15 silica. Fe-SBA-15 exhibited strong magnetic properties, with a magnetization value of 8.8?emu?g-1. The iron content in Fe-SBA-15 was determined by atom adsorption spectroscopy. Fe-SBA-15 was successfully used for the magnetic separation of three aromatic compounds in water. Our results suggest wide applicability of Fe-SBA-15 magnetic materials for the rapid and efficient separation of various compounds. 1. Introduction Mesoporous SBA-15 silica molecular sieves of large pore diameter (up to 30?nm) and area (up to 1000?m2?g-1) [1] show excellent homogeneity and stability and can be well controlled for adsorption/desorption processes [2]. Mesoporous silica materials, especially mesoporous SBA-15 molecular sieves, have been modified with 3-mercaptopropyl, 3-aminopropyl, octyl, or octadecyl groups for the separation and analysis of inorganic ions, organic compounds, and biological molecules [2–5]. However, SBA-15 is notoriously difficult to separate from solution. Magnetic separation is a useful tool because of its fast recovery, high efficiency, and low high cost [6]. Inclusion of magnetic components in modified materials allows convenient and economical magnetic separation instead of centrifugation and filtration steps on application of an appropriate magnetic field [7–9]. Because of their potential applications in this approach, the preparation of Co, Co/Fe, α-Fe2O3, γ-Fe2O3, and Fe3O4 magnetic SBA-15 materials have been reported [10–15]. We propose a convenient and effective procedure for iron doping of mesoporous SBA-15 silica
Structure, expression differentiation and evolution of duplicated fiber developmental genes in Gossypium barbadense and G. hirsutum
Huayu Zhu, Xiaoyong Han, Junhong Lv, Liang Zhao, Xiaoyang Xu, Tianzhen Zhang, Wangzhen Guo
BMC Plant Biology , 2011, DOI: 10.1186/1471-2229-11-40
Abstract: The sequence and structure of 70.59% genes were conserved with the same exon length and numbers in different species, while 29.41% genes showed diversity. There were 15 genes showing independent evolution between the A- and D-subgenomes after polyploid formation, while two evolved via different degrees of colonization. Chromosomal location showed that 22 duplicate genes were located in which at least one fiber quality QTL was detected. The molecular evolutionary rates suggested that the D-subgenome of the allotetraploid underwent rapid evolutionary differentiation, and selection had acted at the tetraploid level. Expression profiles at fiber initiation and early elongation showed that the transcripts levels of most genes were higher in Hai7124 than in TM-1. During the primary-secondary transition period, expression of most genes peaked earlier in TM-1 than in Hai7124. Homeolog expression profile showed that A-subgenome, or the combination of A- and D-subgenomes, played critical roles in fiber quality divergence of G. hirsutum and G. barbadense. However, the expression of D-subgenome alone also played an important role.Integrating analysis of the structure and expression to fiber development genes, suggests selective breeding for certain desirable fiber qualities played an important role in divergence of G. hirsutum and G. barbadense.Cotton (Gossypium spp.) is the world's most important fiber crop plant. While most of the > 50 Gossypium species are diploid (n = 13), five are allopolyploids (n = 26), originating from an interspecific hybridization event between A- and D-genome diploid species. Humans have independently domesticated four different species for their fiber, two of which are diploids, Gossypium herbaceum and G. arboreum, and two are allopolyploids, G. hirsutum and G. barbadense [1].Alhough G. hirsutum and G. barbadense probably originated from a single hybridization event between A- and D- diploid species, the two have very different agronomic and fiber q
Sexually Dimorphic Expression of vasa Isoforms in the Tongue Sole (Cynoglossus semilaevis)
Zhongkai Wang, Jinning Gao, Huayu Song, Xiaomeng Wu, Yan Sun, Jie Qi, Haiyang Yu, Zhigang Wang, Quanqi Zhang
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0093380
Abstract: The vasa gene encodes an ATP-dependent RNA helicase of the DEAD box protein family that functions in a broad range of molecular events involving duplex RNA. In most species, the germline specific expression of vasa becomes a molecular marker widely used in the visualization and labeling of primordial germ cells (PGCs) and a tool in surrogate broodstock production through PGC transplantation. The vasa gene from tongue sole (Cynoglossus semilaevis) was characterized to promote the development of genetic breeding techniques in this species. Three C. semilaevis vasa transcripts were isolated, namely vas-l, vas-m, and vas-s. Quantitative real-time PCR results showed that C. semilaevis vasa transcripts were prevalently expressed in gonads, with very weak expression of vas-s in other tissues. Embryonic development expression profiles revealed the onset of zygotic transcription of vasa mRNAs and the maternal deposit of the three transcripts. The genetic ZW female juvenile fish was discriminated from genetic ZZ males by a pair of female specific primers. Only the expression of vas-s can be observed in both sexes during early gonadal differentiation. Before PGCs started mitosis, there was sexually dimorphic expression of vas-s with the ovary showing higher levels and downward trend. The results demonstrated the benefits of vasa as a germline specific marker for PGCs during embryonic development and gonadal differentiation. This study lays the groundwork for further application of C. semilaevis PGCs in fish breeding.
Pretreated methods on loess-palaeosol samples granulometry
Huayu Lu,Zhisheng An
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02898920
Abstract: Twenty representative samples were collected from the Chinese loess plateau and each sample was prepared in 6 different ways respectively in order to test the influences of pretreated methods on grain size measurement. The results show that (i) different pretreated methods can make a big difference for the samples granulometry; (ii) soaking in distilled water for one day, and then treating with an ultrasonic machine for 10 min can make the sample dispersed.
Structures and isomerization of cabenoids H2CLiBr
Huayu Qiu,Conghao Deng
Chinese Science Bulletin , 1997, DOI: 10.1007/BF02882436
Abstract:
Pretreated methods on loess-palaeosol samples granulometry

Huayu Lu,Zhisheng An,

科学通报(英文版) , 1998,
Abstract: Twenty representative samples were collected from the Chinese loess plateau and each sample was prepared in 6 different ways respectively in order to test the influences of pretreated methods on grain size measurement. The results show that (i) different pretreated methods can make a big difference for the samples granulometry; (ii) soaking in distilled water for one day, and then treating with an ultrasonic machine for 10 min can make the sample dispersed.
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