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Search Results: 1 - 10 of 127201 matches for " Guangyu Li "
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Co-orbital restricted three-body problem and its application
GuangYu Li
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-010-9998-4
Nano-porous ultra-high specific surface ultrafine fibers
Xinsong Li,Guangyu Nie
Chinese Science Bulletin , 2004, DOI: 10.1007/BF03183424
Abstract: Nano-porous ultra-high specific surface ultrafine fibers are created by the method of “electrospinning-phase separation-leaching” (EPL) for the first time. First of all, polymer solutions of polyacrylonitrile (PAN) and polyvinylpyrrolidone (PVP) blends dissolved in co-solvent are electrospun to make ultrafine fibers when charged to high voltages. The incompatibility of PAN and PVP induces phase separation to form microdomains of PVP in the polymer blend ultrafine fibers. Then, PVP microdomains in the blend fibers are leached out in water, and porous PAN ultrafine fibers are obtained. Lastly, the surface and cross-section of the porous ultrafine fibers are observed in detail by field emission scanning electron microscope (FE-SEM), and the specific surface of the ultrafine fibers is measured by means of nitrogen absorption. With increasing the content of PVP, the specific surface area of the ultrafine fibers increases apparently. The specific surface area of the porous ultrafine fibers with the diameter of 2130 nm is more than 70 m2·g 1. The cross-section of the PAN porous ultrafine fibers after leaching of PVP microdomains from polymer blend fibers with the feed ratio of PAN/PVP of 10/20 shows the characteristic of porous structure with pore diameter of ca 30 nm according to FESEM photo.
Constraint on intermediate-range gravity from earth-satellite and lunar orbiter measurements, and lunar laser ranging
Guangyu Li,Haibin Zhao
Physics , 2005, DOI: 10.1142/S0218271805007176
Abstract: In the experimental tests of gravity, there have been considerable interests in the possibility of intermediate-range gravity. In this paper, we use the earth-satellite measurement of earth gravity, the lunar orbiter measurement of lunar gravity, and lunar laser ranging measurement to constrain the intermediate-range gravity from lambda=1.2*10^{7}m - 3.8*10^{8}m. The limits for this range are alpha=10^{-8}-5*10^{-8}, which improve previous limits by about one order of magnitude in the range lambda=1.2*10^{7}m-3.8*10^{8}m.

Xu Li,Shi Guangyu,

大气科学进展 , 1985,
Abstract: The longwave (0-2380 cm-1) cooling rate due to water vapor in the troposphere and the stratosphere has been calculated by a new infrared transmission model in this paper. An exact scheme is used for treating the integration over wavenumber and the inhomogeneous path in the atmosphere. It is shown that the atmospheric window region (730-1200 cm-1) (mainly water vapor continuum) plays an important role in the total cooling near the surface, about 72% of the total cooling lying in this region at the height of 1 km; the CG approximation used for an inhomogeneous path is fairly applicable for calculating the cooling rate due to water vapor, with a maximum error of 0.16 K/day throughout the troposhere and the stratosphere; on the other hand, the error due to the diffusivity factor of 1.66 appears to be slightly larger near the surface. In this study, the influences on the calculation of above infrared cooling rate, of the temperature-dependence of the absorption coefficients of water vapor, the upper level cutoff and the integration step for altitude, and the substitution of the quasi-grey approximation for the exact integration over wavenumber, are also examined.
The Dynamical Simulations of the Planets Orbiting GJ 876
Ji Jianghui,Li Guangyu,Liu Lin
Physics , 2002, DOI: 10.1086/340350
Abstract: We have performed simulations to investigate the dynamics of the M dwarf star GJ 876 in an attempt to reveal any stabilizing mechanism for sustaining the system.We simulated different coplanar and noncoplanar configurations of two-planet systems and other cases.From the simulations,we found that the 2 :1 mean-motion resonance between two planets can act as an effective mechanism for maintaining the stability of the system.This result is explained by a proposed analytical model.Using this model,we studied the region of motion of the inner planet by varying the parameters of the system,and we detected that the analytical results are well consistent with the numerical simulations.
Role of the NC-Loop in Catalytic Activity and Stability in Lipase from Fervidobacterium changbaicum
Binchun Li, Guangyu Yang, Lie Wu, Yan Feng
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0046881
Abstract: Flexible NC-loops between the catalytic domain and the cap domain of the α/β hydrolase fold enzymes show remarkable diversity in length, sequence, and configuration. Recent investigations have suggested that the NC-loop might be involved in catalysis and substrate recognition in many enzymes from the α/β hydrolase fold superfamily. To foster a deep understanding of its role in catalysis, stability, and divergent evolution, we here systemically investigated the function of the NC-loop (residues 131–151) in a lipase (FClip1) from thermophilic bacterium Fervidobacterium changbaicum by loop deletion, alanine-scanning mutagenesis and site-directed mutagenesis. We found that the upper part of the NC-loop (residues 131–138) was of great importance to enzyme catalysis. Single substitutions in this region could fine-tune the activity of FClip1 as much as 41-fold, and any deletions from this region rendered the enzyme completely inactive. The lower part of the NC-loop (residues 139–151) was capable of enduring extensive deletions without loss of activity. The shortened mutants in this region were found to show both improved activity and increased stability simultaneously. We therefore speculated that the NC-loop, especially the lower part, would be a perfect target for enzyme engineering to optimize the enzymatic properties, and might present a hot zone for the divergent evolution of α/β hydrolases. Our findings may provide an opportunity for better understanding of the mechanism of divergent evolution in the α/β hydrolase fold superfamily, and may also guide the design of novel biocatalysts for industrial applications.
Quantitative PCR used to Assess HIV-1 Integration and 2-LTR Circle Formation in Human Macrophages, Peripheral Blood Lymphocytes and a CD4+ Cell Line
Brian Friedrich, Guangyu Li, Natallia Dziuba, Monique R Ferguson
Virology Journal , 2010, DOI: 10.1186/1743-422x-7-354
Abstract: In this study, we utilized a well-defined, sensitive two-step quantitative real-time PCR method to detect HIV-1 integration as well as conventional real-time PCR to detect 2-LTR circle formation in human macrophages and PBL isolated from six different healthy donors, as well as U373 CD4+ cells by infecting with HIV-1SX (R5) or dual-tropic isolate HIV-189.6 (R5/X4) virus strains. We used the FDA-approved integrase inhibitor, raltegravir, to determine quantitative differences of integrated HIV viral cDNA in HIV-1 infected cells with and without raltegravir treatment. Our results show that integration and 2-LTR circle formation can be assessed in primary macrophages, PBL, and a CD4+ cell line by this method. Specifically, our results demonstrate that this two-step real-time PCR method can distinguish between HIV-1 integrated viral cDNA and non-integrated nuclear HIV-1 2-LTR circles caused by impaired integration with raltegravir-treatment. This further confirms that only integrated HIV-1 cDNA can be specifically amplified and quantified by two-step PCR without non-specifically detecting non-integrated viral cDNA.These results consistently demonstrate that the well-established real-time PCR assays used are robust, sensitive and quantitative for the detection of HIV-1 integration and 2-LTR circle formation in physiologically relevant human macrophages and PBL using lab-adapted virus strains, instead of pseudovirus. With two-step real-time PCR, we show that unintegrated, nuclear HIV-1 cDNA is not detected in raltegravir-treated cells, while specific for only integrated HIV-1 cDNA in non-treated cells. These methods could be applied as a useful tool in further monitoring specific therapy in HIV-1 infected individuals.Human immunodeficiency virus type 1 (HIV-1) is known to infect several primary cell types, predominantly CD4+ T lymphocytes and macrophages. HIV-1 infection results in a gradual decline in the number of CD4+ T cells, leading to the development of AIDS. Macroph

Li Guangyu,Huang Yue,

岩石力学与工程学报 , 2001,
Abstract: The concept of linewise observation and portable instruments are introduced. The instruments can be used in most geotechnique engineering for field monitoring. Along a measuring line, marks and casings in same interval are fixed instead of probes. In this way one probe can serve many measuring boreholes and projets as well. Some probes can measure axial strain, some can measure both axial and lateral strain or displacement in one hole in any directions. The information and accuracy obtained will be much more and higher than that gained by fixed probes based on pointwise observation, such as concrete strain guage. Some applications on field monitoring in geomechanics are intraduced briefly.
An exact calculation of infrared cooling rate due to water vapor

Xu Li,Shi Guangyu,

大气科学 , 1986,
Abstract: 本文用一种新的红外透过率模式计算了对流层和平流层水汽的长波(0—2380cm~(-1))冷却率分布.在计算中,我们精确处理了频率积分以及非均匀大气路径效应.结果表明:在近地面层,大气窗区(730—1200cm~(-1))(主要是水汽连续吸收)对总的冷却率贡献很大,在1公里处大约占72%;通常所用的处理非均匀大气路径及漫射辐射的CG近似和1.66漫射因子近似,基本上适用于水汽冷却率的计算.在整个对流层和平流层,它们所带来的最大误差不超过0.16K/日和0.19K/日.同时,我们还考查了水汽吸收系数的温度效应
A Single Lys Residue on the First Intracellular Loop Modulates the Endoplasmic Reticulum Export and Cell-Surface Expression of α2A-Adrenergic Receptor
Yi Fan, Chunman Li, Jianhui Guo, Gang Hu, Guangyu Wu
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0050416
Abstract: Export from the endoplasmic reticulum (ER) represents an initial step in intracellular trafficking of G protein-coupled receptors (GPCRs). However, the underlying molecular mechanisms remain poorly understood. We have previously demonstrated that a highly conserved Leu residue on the first intracellular loop (ICL1) is required for exit of several GPCRs from the ER. Here we found that, in addition to Leu64 residue in the ICL1, the neighboring positively charged residue Lys65also modulates the cell-surface transport of α2A-adrenergic receptor (α2A-AR). Mutation of Lys65 to Ala, Glu and Gln significantly attenuated, whereas mutation of Lys65 to Arg strongly augmented α2A-AR expression at the cell surface. Consistent with the effects on the cell-surface expression of α2A-AR, mutation of Lys65 to Ala and Arg produced opposing effects on α2A-AR-mediated ERK1/2 activation. Furthermore, confocal microscopy revealed that the α2A-AR mutant K65A displayed a strong intracellular expression pattern and was extensively co-localized with the ER marker DsRed2-ER, suggestive of ER accumulation. These data provide the first evidence indicating an important function for a single Lys residue on the ICL1 in the ER export and cell-surface expression of α2A-AR. These data also suggest that the ICL1 may possess multiple signals that control the cell-surface targeting of GPCRs via distinct mechanisms.
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