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Search Results: 1 - 10 of 111982 matches for " Ying-hua Chen "
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Application of stable carbon isotope techniques to research into water stress
碳稳定同位素技术在植物水分胁迫研究中的应用

CHEN Ying-Hua,
陈英华

生态学报 , 2004,
Abstract: 植物体的碳稳定同位素组成主要由植物本身的生物学特性决定 ,但环境胁迫对其影响也十分明显。综述了碳稳定同位素技术在研究植物水分利用效率、生物量高低及判断历史气候依据等研究领域的进展 ,阐明了植物体的 δ1 3C值对干旱、盐分及其它环境因素的变化所引起的水分胁迫的响应 ,并对碳稳定同位素对水分胁迫的响应机理进行了归纳和推断
Coherent-incoherent transition in a Cooper-pair-box coupled to a quantum oscillator: an equilibrium approach
Ying-Hua Huang, Hang Wong,Zhi-De Chen
The Open Condensed Matter Physics Journal , 2008, DOI: 10.2174/1874186X00801010019]
Abstract: Temperature effect on quantum tunneling in a Cooper-pair-box coupled to a quantum oscillator is studied by both numerical and analytical calculations. It is found that, in strong coupling regions, coherent tunneling of a Cooper-pair-box can be destroyed by its coupling to a quantum oscillator and the tunneling becomes thermally activated as the temperature rises, leading to failure of the Cooper-pair-box. The transition temperature between the coherent tunneling and thermo-activated hopping is determined and physics analysis based on small polaron theory is also provided.
The temperature influence on quantum tunneling in the spin-boson model
Zhi-De Chen,Ying-Hua Huang,Hang Wong
Physics , 2008,
Abstract: The existing studies of the temperature effect of the spin-boson model show that the tunneling splitting will increase with temperature, no matter how weak the couplings are between the bath and the spin. However, the small polaron theory said that in the weak coupling and low temperature regime, the tunneling is, in fact, dominated by the diagonal transitions whereas this diagonal contribution to the tunneling should be faded away with increasing temperature. Taking advantage of the analysis originated from the Feynman-Vernon's influence functional theory, the influence on the tunneling by the phonon bath can be expressed as a product of the effects of every single phonon mode, which can be studied by numerical exact diagonalization. We find that, in the weak coupling and low temperature regime, all the spin-single-mode systems exhibit the same decreasing dependence of tunneling on increasing temperature. In turn, with the conclusion of influence functional theory, the tunneling of the spin-boson model should decrease and it is independent of the bath structure. In the strong coupling regime, however, the temperature effect reverses from suppressing to enhancing the tunneling with the increase of temperature. Discrepancies between the old theories and the small polaron theory are also explained.
Coherent-incoherent transition in a Cooper-pair-box coupled to a quantum oscillator: an equilibrium approach
Ying-Hua Huang,Hang Wong,Zhi-De Chen
Physics , 2008, DOI: 10.2174/1874186X00801010019
Abstract: Temperature effect on quantum tunneling in a Cooper-pair-box coupled to a quantum oscillator is studied by both numerical and analytical calculations. It is found that, in strong coupling regions, coherent tunneling of a Cooper-pair-box can be destroyed by its coupling to a quantum oscillator and the tunneling becomes thermally activated as the temperature rises, leading to failure of the Cooper-pair-box. The transition temperature between the coherent tunneling and thermo-activated hopping is determined and physics analysis based on small polaron theory is also provided.
HIV-1 gp41 Core with Exposed Membrane-Proximal External Region Inducing Broad HIV-1 Neutralizing Antibodies
Ji Wang,Pei Tong,Lu Lu,Leilei Zhou,Liling Xu,Shibo Jiang,Ying-hua Chen
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0018233
Abstract: The membrane-proximal external region (MPER) of the HIV-1 gp41 consists of epitopes for the broadly cross-neutralizing monoclonal antibodies 2F5 and 4E10. However, antigens containing the linear sequence of these epitopes are unable to elicit potent and broad neutralizing antibody responses in vaccinated hosts, possibly because of inappropriate conformation of these epitopes. Here we designed a recombinant antigen, designated NCM, which comprises the N- and C-terminal heptad repeats that can form a six-helix bundle (6HB) core and the MPER domain of gp41. Two mutations (T569A and I675V) previously reported to expose the neutralization epitopes were introduced into NCM to generate mutants named NCM(TA), NCM(IV), and NCM(TAIV). Our results showed that NCM and its mutants could react with antibodies specific for 6HB and MPER of gp41, suggesting that these antigens are in the form of a trimer of heterodimer (i.e., 6HB) with three exposed MPER tails. Antigen with double mutations, NCM(TAIV), elicited much stronger antibody response in rabbits than immunogens with single mutation, NCM(TA) and NCM(IV), or no mutation, NCM. The purified MPER-specific antibodies induced by NCM(TAIV) exhibited broad neutralizing activity, while the purified 6HB-specific antibodies showed no detectable neutralizing activity. Our recombinant antigen design supported by an investigation of its underlying molecular mechanisms provides a strong scientific platform for the discovery of a gp41 MPER-based AIDS vaccine.
Poly[μ3-hydroxido-μ-(pyridine-2,4,6-tricarboxylato)-dilead(II)]
Ying-Hua Zhou,Jian Chen,Yong Cheng,Nian-Rong Zhang
Acta Crystallographica Section E , 2011, DOI: 10.1107/s1600536810049275
Abstract: The asymmetric unit of the title coordination polymer, [Pb2(C8H2NO6)(OH)]n, contains two crystallographically independent PbII ions, one pyridine-2,4,6-tricarboxylate (ptc) trianion and one hydroxide anion. One of the PbII atoms is coordinated by one pyridine N and four carboxylate O atoms from the ptc trianion and a hydroxide O atom in a distorted octahedral geometry. The other PbII atom is five-coordinated by three carboxylate O atoms and two hydroxide O atoms in a distorted tetragonal–pyramidal geometry. Four neighbouring PbII atoms are bridged through two μ3-hydroxide ligands, forming the centrosymmetric Pb4(OH)2 core. The three-dimensional structure is further achieved through bridging carboxylate groups. There are also O—H...O hydrogen bonds between the hydroxide ligand and the carboxylate group.
Gardenia jasminoides attenuates hepatocellular injury and fibrosis in bile duct-ligated rats and human hepatic stellate cells
Ying-Hua Chen,Tian Lan,Jing Li,Chun-Hui Qiu
World Journal of Gastroenterology , 2012, DOI: 10.3748/wjg.v18.i48.7158
Abstract: AIM: To investigate the anti-hepatofibrotic effects of Gardenia jasminoides in liver fibrosis. METHODS: Male Sprague-Dawley rats underwent common bile duct ligation (BDL) for 14 d and were treated with Gardenia jasminoides by gavage. The effects of Gardenia jasminoides on liver fibrosis and the detailed molecular mechanisms were also assessed in human hepatic stellate cells (LX-2) in vitro. RESULTS: Treatment with Gardenia jasminoides decreased serum alanine aminotransferase (BDL vs BDL + 100 mg/kg Gardenia jasminoides, 146.6 ± 15 U/L vs 77 ± 6.5 U/L, P = 0.0007) and aspartate aminotransferase (BDL vs BDL + 100 mg/kg Gardenia jasminoides, 188 ± 35.2 U/L vs 128 ± 19 U/L, P = 0.005) as well as hydroxyproline (BDL vs BDL + 100 mg/kg Gardenia jasminoides, 438 ± 40.2 μg/g vs 228 ± 10.3 μg/g liver tissue, P = 0.004) after BDL. Furthermore, Gardenia jasminoides significantly reduced liver mRNA and/or protein expression of transforming growth factor β1 (TGF-β1), collagen type I (Col I) and α-smooth muscle actin (α-SMA). Gardenia jasminoides significantly suppressed the upregulation of TGF-β1, Col I and α-SMA in LX-2 exposed to recombinant TGF-β1. Moreover, Gardenia jasminoides inhibited TGF-β1-induced Smad2 phosphorylation in LX-2 cells. CONCLUSION: Gardenia jasminoides exerts antifibrotic effects in the liver fibrosis and may represent a novel antifibrotic agent.
HIV and Hepatitis C Virus Testing Delays at Methadone Clinics in Guangdong Province, China
Ying-Hua Xia, Megan M. McLaughlin, Wen Chen, Li Ling, Joseph D. Tucker
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0066787
Abstract: In China, injection drug use is a major transmission route for HIV and hepatitis C virus (HCV) infection. Timely HIV and HCV testing among drug users is vital to earlier diagnosis, linkage to care, and retention. This study aimed to examine HIV and hepatitis C virus (HCV) testing delays at methadone clinics in Guangdong Province, China, and identify individual-level and clinic-level factors associated with delayed testing. Data from 13,270 individuals at 45 methadone clinics in Guangdong were abstracted from a national web-based surveillance database. A two-level binomial logit model was used to examine the association between individual- and clinic-level factors and delayed HIV and HCV testing, defined as receiving a test seven or more days after initial entry into the methadone system. Among 10,046 patients tested for HIV, 1882 (18.7%) had delayed testing; among 10,404 patients tested for HCV, 1542 (14.8%) had delayed testing. Among delayed testers, the median time to HCV testing was significantly longer than the median time to HIV testing (73 vs. 54 days, p<0.05). In the multivariate analysis, the likelihood of delayed HIV testing was higher among individuals with high school or greater education (adjusted odds ratio [aOR] 1.32, 95% confidence interval [CI] 1.02–1.72) and individuals enrolled at clinics with more patients (aOR 1.41, 95% CI 1.05–1.91, for each increase in 100). The likelihood of delayed HCV testing was higher among women (aOR 1.51, 95% CI 1.11–2.06) and employed individuals (aOR 1.21, 95% CI 1.02–1.43). Delayed testing for HIV and HCV is common among patients at methadone clinics in Guangdong, with many patients experiencing delays of two or more months. Structural interventions are needed to expedite testing once individuals enter the methadone maintenance program.
Validation of a Novel Clinical Prediction Score for Severe Coronary Artery Diseases before Elective Coronary Angiography
Zhang-Wei Chen, Ying-Hua Chen, Ju-Ying Qian, Jian-Ying Ma, Jun-Bo Ge
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0094493
Abstract: Objectives Coronary artery disease (CAD) severity is associated with patient prognosis. However, few efficient scoring systems have been developed to screen severe CAD in patients with stable angina and suspected CAD before coronary angiography. Here, we present a novel scoring system for CAD severity before elective coronary angiography. Methods Five hundred fifty-one patients with stable angina who were admitted for coronary angiography were enrolled in this study. Patients were divided into training (n = 347) and validation (n = 204) cohorts. Severe CAD was defined as having a Gensini score of 20 or more. All patients underwent echocardiography (ECG) to detect ejection fraction and aortic valve calcification (AVC). Multivariable analysis was applied to determine independent risk factors and develop the scoring system. Results In the training cohort, age, male sex, AVC, abnormal ECG, diabetes, hyperlipidemia, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol were identified as independent factors for severe CAD by multivariable analysis, and the Severe Prediction Scoring (SPS) system was developed. C-indices of receiver operating characteristic (ROC) curves for severe CAD were 0.744 and 0.710 in the training and validation groups, respectively. The SPS system also performed well during calibration, as demonstrated by Hosmer-Lemeshow analysis in the validation group. Compared with the Diamond-Forrester score, the SPS system performed better for severe CAD prediction before elective coronary angiography. Conclusions Severe CAD prediction was achieved by analyzing age, sex, AVC, ECG, diabetes status, and lipid levels. Angina patients who achieve high scores using this predicting system should undergo early coronary angiography.
Spectrophotometric determination of micro-cadmium in water after ionic liquid extraction
离子液体萃取光度法测定水中微量镉

LI Shan,CHEN Zhen,WANG Qian,WANG Ying-hua,
李姗
,陈珍,王千,王英华

冶金分析 , 2012,
Abstract: A new extraction spectrophotometry for the determination of micro-cadmium was proposed.In Na2B4O7-NaOH buffer medium at pH 10.8,the Cd-Cadion complex formed by 1-(4-nitrobenzophenone)-3-(4-phenylazophenyl)-triazene(Cadion) and Cd2+ could be extracted by little ionic liquid(1-butyl-3-methylimidazole hexafluorophosphate,).After centrifugal separation,the content of cadmium in ionic liquid phase was directly determined by spectrophotometry at maximum absorption wavelength(517 nm).The linear range of this method was 1.0-62.5 ng/mL,the detection limit was 0.22 ng/mL,apparent molar absorptivity was 6.9×105 L·mol-1·cm-1,the enhancement factor was 29.5,and the relative standard deviation(RSD,50 ng/mL,n=6) was 2.1 %.The proposed method was directly applied to the determination of micro-cadmium in water sample with recoveries of 96.7 %-108.5 %.
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