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Search Results: 1 - 10 of 42696 matches for " Juanjuan Xu "
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Positive solutions for multipoint boundary-value problem with parameters
Juanjuan Xu,Zhongli Wei
Electronic Journal of Differential Equations , 2008,
Abstract: In this paper, we study a generalized Sturm-Liouville boundary-value problems with two positive parameters. By constructing a completely continuous operator and combining fixed point index theorem and some properties of the eigenvalues of linear operators, we obtain sufficient conditions for the existence of at least one positive solution.
The Factors on Removal of Zinc Cation from Aqueous Solution by Bentonite  [PDF]
Shuli Ding, Juanjuan Shen, Bohui Xu, Qinfu Liu, Yuzhuang Sun
Natural Resources (NR) , 2011, DOI: 10.4236/nr.2011.22015
Abstract: The removing zinc cation from aqueous solution by Ca-bentonite and Na-exchanged bentonite was studied. The factors such as the initial concentration of Zn2+, the liquid-to-solid ratio, pH, adsorption time, stirring speed, coexisting ions, temperature and bentonite particle size were investigated. The results show that the adsorption process of bentonite accorded with the Freundlich isotherm model, the removal of Zn2+ by Ca-bentonite and Na-exchanged bentonite reached equilibrium in 2 h, and adsorption of Na- bentonite was superior to Ca-bentonite. The adsorption rate of zinc increased with increasing pH, temperature, stirring speed, time span and with decreasing bentonite particle, the initial concentration of Zn2+ and the liquid-to-solid ratio. In mixed solution which contains Pb2+and Cr6+, Pb2+ has no influ- ence on the removal of Zn2+ by both the bentonites while Cr6+can decease it.
Enantioseparation of Three Non-Steroidal Anti-Inflammatory Agents on Chiral Stationary Phase by HPLC  [PDF]
Xuejun Zhang, Zou Li, Baochun Shen, Juanjuan Chen, Xiuzhu Xu
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2012, DOI: 10.4236/jasmi.2012.21004
Abstract: This paper reported the enantioseparation of Naproxen, Ketoprofen and Etodolac on tartardiamide-DMB chiral stationary phase (CHI-DMB) and (R,R) –DNB-DPEDA chiral stationary phase,using hexane as the mobile phase with various modifiers. The influence of the mobile phase composition including the type and concentration of the modifiers in hexane and the structures of the analytes on the chiral separation was studied. The results indicated that the steric structure of the solute, especially the environment of the chiral carbon, was the predominant factor for the chiral recognition. The type, the steric structure and the concentration of the modifiers also influence the retention factor and the resolution. The chiral recognition mechanism of the analytes on CHI-DMB and (R,R) –DNB-DPEDA was also discussed. The hydrogen-bonding interaction played an important role on enantioseparation on CHI-DMB, so did the π-π interaction. On (R,R) –DNB-DPEDA the π-π interaction was the key for the solutes retention and enantioseparation, while hydrogen-bonding interaction was not important. Additionally, it has been demonstrated that enantioselectivity and retention was also dependent upon the nature and functional groups on the aromatic ring of solutes and CSP.
Effects of Lévy Noise on a bistable Duffing System
Yong Xu,Juanjuan Li,Jing Feng
Physics , 2013,
Abstract: This paper numerically investigates the mean first passage time (MFPT) and phase transition of a bistable Duffing system driven by L\'evy stable noise, which can reduce to the common Gaussian noise with the stability index 2. We obtain the stationary probability density functions by using Monte Carlo method to describe the change in distribution law and the influences of L\'evy noise parameters on the stationary probability densities are discussed. The results indicate that the stability index, noise intensity and skewness parameter of L\'evy noise can induce the phase transition behaviors (namely, the qualitative change of stationary probability density function). Furthermore, the MFPT is calculated as functions of different parameters, which implies that the effects of the stability index, noise intensity and the skewness parameter on MFPT are quite different, and apparent distinctions between L\'evy and Gaussian noise can be observed.
Cloning and Bioinformatics Analysis of Rosa rugosa β-1,3-Glucanase Gene (RrGlu)  [PDF]
Yanan Fu, Juanjuan Sun, Yan Ma, Shutang Xing, Lanyong Zhao, Zongda Xu, Xiaoyan Yu
American Journal of Plant Sciences (AJPS) , 2016, DOI: 10.4236/ajps.2016.73040
Abstract: In order to reveal which role the callose played in R. rugosa pollination incompatibility, the full-length cDNA sequence of β-1,3-glucanase gene was cloned for the first time from the stylus of Rosa rugosa “Tanghong” with RT-PCR and RACE methods and named as RrGlu. The full-length cDNA is 1380 bp with an open reading frame of 1041 bp, encoding 346 amino acids. The derived protein has a molecular weight of 37.85 kD, a calculated pI of 9.12, a pfam00332 conserved domain at position 36 - 345, and belongs to glycosyl hydrolase family 17. The derived protein is a hydrophilic protein secreted into the vacuole. There is a signal peptide cleavage site at position 34 - 35, a transmembrane domain at position 13 - 32, six Ser phosphorylation sites, three Thr phosphorylation sites, three Tyr phosphorylation sites, one N-glycosylation site, and five O-glycosylation sites. There are 31.50% α-helixes, 30.92% random coil, 25.14% extended peptide chain, and 12.43% β-corner structure. This protein and the Glu protein from eight other species, including Prunus persica, share a sequence homology of greater than 72%; all of the proteins contain a pfam00332 conserved domain and a β-1,3-glucanase active center sequence (LIVM)-X-(LIVMFYW)3-(STAG)-E-(ST)-G-W-P-(ST)-X-G. Furthermore, their phylogenetic relationships are consistent with their traditional classifications. These results were meaningful to reveal the molecular mechanism of R. rugosa pollination incompatibility and improve the theory and techniques of breeding ornamental R. rugosa.
Expression Vector Construction and Genetic Transformation of Rosa rugosa β-l,3-Glucanase Gene (RrGlu)  [PDF]
Shutang Xing, Juanjuan Sun, Zhihong Peng, Yanan Fu, Lanyong Zhao, Zongda Xu, Xiaoyan Yu
American Journal of Plant Sciences (AJPS) , 2017, DOI: 10.4236/ajps.2017.83034
Abstract: In order to lay a foundation for researching the function of Rosa rugose (R. rugosa) RrGlu gene, the RrGlu gene was amplified from the styles of R. rugosa “Tanghong”, a gene expression vector named PBI121-RrGlu was constructed and the vector was introduced into tobacco with the agrobacterium-mediated method. PCR results showed that the RrGlu gene was integrated into the tobacco genome.
Lévy Noise Induced Switch in the Gene Transcriptional Regulatory System
Yong Xu,Jing Feng,JuanJuan Li,Huiqing Zhang
Quantitative Biology , 2012, DOI: 10.1063/1.4775758
Abstract: Gene transcriptional regulatory is an inherently noisy process. In this paper, the study of fluctuations in a gene transcriptional regulatory system is extended to the case of L\'evy noise, a kind of non-Gaussian noises which can describe unpredictable jump changes of the random environment. The stationary probability density is given to explore the key roles of L\'evy noise in the gene regulatory networks. The results demonstrate that the parameters of L\'evy noise, including noise intensity, stability index and skewness parameter can induce switches between distinct gene-expression states. A further concern is the switching time (from the high concentration state to the low concentration one or from the low concentration state to the high concentration one), which is a random variable and often referred to as the mean first passage time. The effects of L\'evy noise in expression time and degradation time is studied by computing the mean first passage time in two directions and a number of different peculiarities of non-Gaussian L\'evy noise compared with Gaussian noise are observed.
Lévy Noise-Induced Stochastic Resonance in a Bistable System
Yong Xu,Juanjuan Li,Jing Feng,Huiqing Zhang,Wei Xu,Jinqiao Duan
Physics , 2012, DOI: 10.1140/epjb/e2013-31115-4
Abstract: Stochastic resonance phenomenon induced by non-Gaussian L\'evy noise in a second-order bistable system is investigated. The signal-noise-ratio for different parameters is computed by an efficient numerical scheme. The influences of the noise intensity, stability index of L\'evy noise and amplitude of external signal on the occurrence of stochastic resonance phenomenon are characterized. This implies that a high amplitude of signal not only enhances the output power spectrum of system but also promotes stochastic resonance, and a proper adjustment of L\'evy noise intensity in a certain range enlarges the peak value of output power spectrum which is significant for stochastic resonance. Moreover, with the optimal damping parameter, lowering the stability index leads to larger fluctuations of L\'evy noise, and further reduces the chance of the stochastic resonance.
A Soluble Receptor for Advanced Glycation End-Products Inhibits Hypoxia/Reoxygenation-Induced Apoptosis in Rat Cardiomyocytes via the Mitochondrial Pathway
Caixia Guo,Xiangjun Zeng,Juanjuan Song,Min Zhang,Hongxia Wang,Xiaowei Xu,Fenghe Du,Buxing Chen
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms130911923
Abstract: Severe myocardial dysfunction and tissue damage resulting from ischemia/reperfusion (I/R) is a common clinical scenario in patients with certain types of heart diseases and therapies such as thrombolysis, percutaneous coronary intervention, coronary artery bypass grafting, and cardiac transplantation. The underlining mechanism of endogenous cardiac protection after I/R injury has been a focus of current research. Growing evidences suggests that soluble receptor for advanced glycation end-products (sRAGE) has a cardioprotective effect; however, its role in I/R injury remains unclear. We hypothesized that exogenous administration of sRAGE during hypoxia/reoxygenation (H/R) induces cardioprotection by inhibiting cardiomyocyte apoptosis via multiple signals, involving mitochondrial membrane potential (MMP), the mitochondrial permeability transition pore (mPTP), mitochondrial cytochrome c, caspase-3, Bcl-2 and Bax. Neonatal rat cardiomyocytes underwent hypoxia for 3-h followed by 2-h reoxygenation or were treated with sRAGE for 10 min before H/R. Compared with H/R alone, sRAGE pretreatment reduced H/R-induced cardiomyocyte apoptosis from 27.9% ± 5.9% to 9.4% ± 0.7% ( p < 0.05). In addition, sRAGE treatment significantly inhibited H/R-induced mitochondrial depolarization and mPTP opening, reduced mitochondrial cytochrome c leakage, caspase-3 and caspase-9 activity, and decreased the ratio of Bax to Bcl-2. Therefore, we conclude that the exogenous administration of sRAGE during H/R is involved in cardioprotection by inhibiting apoptosis via the mitochondrial pathway, which, if further confirmed in vivo, may have important clinical implications during H/R.
Advances in research of land surface evapotranspiration at home and abroad

XinPing Luo,KeLi Wang,Hao Jiang,Jia Sun,JuanJuan Xu,QingLiang Zhu,ZhaoGuo Li,

寒旱区科学 , 2010,
Abstract: Land surface evapotranspiration (ET) is an important part of the hydrologic cycle and energy balances. With the development of remote sensing technology, research on monitoring and estimating of evapotranspiration has made important progress. This paper summarizes advances in measuring and estimating regional evapotranspiration at home and abroad based on traditional methods and remote sensing. This summary includes such methods as Bowen, Gradient, Penman-Monteith, Water Balance, Eddy Correlation, SPAC, Energy Balance and Remote Sensing. Also, the evapotranspiration achievements in the Heihe River Basin are also discussed. Finally, the existing problems in regional evapotranspiration research and future development prospects are also discussed at the conclusion of this paper.
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