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Search Results: 1 - 10 of 104210 matches for " Jigang Zhang "
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Performance Evaluation of a New Type of Polymer Profile Control Agent  [PDF]
Qingwang Liu, Zhe Zhang, Zhenzhong Fan, Zhenzhong Fan, Jigang Wang
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.65040
Abstract: The low-permeability oil and gas resources of our country are quite common and abundant. Their reserve has accounted for one-fifth of total oil reserves of our country, and their yield has constituted the important part of national petroleum annual yield, but its development is very difficult. Polymer gel technology is a technical method of improving sweep efficiency in recent years which substantially increases the viscosity of the polymer solution by adding a crosslinking agent to the polymer produced by intramolecular or intermolecular crosslinking.
The Synthesis and Evaluation of a Novel Inhibitor DN for Carbon Dioxide Corrosion  [PDF]
Qingwang Liu, Tong Zhang, Jigang Wang, Zhenzhong Fan, Ao Sun, Dong Cheng
Open Journal of Composite Materials (OJCM) , 2014, DOI: 10.4236/ojcm.2014.44023
Abstract: During the oil and gas wells exploitation and transportation, carbon dioxide corrosion is one of main reasons for the corrosion of metallic materials. So the methods of preventing and reducing carbon dioxide corrosion have become a widely focused problem. The foreign and domestic practices and experiences show that as an economic, effective and versatile metal corrosion control method, corrosion inhibitor protection technology is suitable for application in oil and gas transportation system. This paper, through the indoor experiment with benzyl chloride, using quinoline as raw materials, synthesizes a kind of quinoline quaternary ammonium salt. The obtained product benzyl chloride quinoline compounded with OP-10 and ethanol to get a novel inhibitor DN for carbon dioxide corrosion, and to evaluate its performance.
The Synthesis and Evaluation of Hydrophobic Association Thickener  [PDF]
Qingwang Liu, Dong Cheng, Jigang Wang, Zhenzhong Fan, Tong Zhang, Ao Sun
Open Journal of Composite Materials (OJCM) , 2015, DOI: 10.4236/ojcm.2015.51001
Abstract: The paper provides a new hydrophobic association polymer fracturing fluid gelatinizer. The hydrophobic association which is the synthesis of three component copolymer complexes, is compounded by micellar copolymerization method. The hydrophobic association is got together through hydrophilic monomer acrylamide monomer N,N-vinyl pyrrolidone monomer with a rigid group N, and hydrophobic monomer N,N-2 dodecyl acrylamide etc. three monomers with sodium dodecyl sulfate as the emulsifier in micellar solution.
Study on mapping Quantitative Trait Loci for animal complex binary traits using Bayesian-Markov chain Monte Carlo approach
Jianfeng Liu,Yuan Zhang,Qin Zhang,Lixian Wang,Jigang Zhang
Science China Life Sciences , 2006, DOI: 10.1007/s11427-006-2024-z
Abstract: It is a challenging issue to map Quantitative Trait Loci (QTL) underlying complex discrete traits, which usually show discontinuous distribution and less information, using conventional statistical methods. Bayesian-Markov chain Monte Carlo (Bayesian-MCMC) approach is the key procedure in mapping QTL for complex binary traits, which provides a complete posterior distribution for QTL parameters using all prior information. As a consequence, Bayesian estimates of all interested variables can be obtained straightforwardly basing on their posterior samples simulated by the MCMC algorithm. In our study, utilities of Bayesian-MCMC are demonstrated using simulated several animal outbred full-sib families with different family structures for a complex binary trait underlied by both a QTL and polygene. Under the Identity-by-Descent-Based variance component random model, three samplers basing on MCMC, including Gibbs sampling, Metropolis algorithm and reversible jump MCMC, were implemented to generate the joint posterior distribution of all unknowns so that the QTL parameters were obtained by Bayesian statistical inferring. The results showed that Bayesian-MCMC approach could work well and robust under different family structures and QTL effects. As family size increases and the number of family decreases, the accuracy of the parameter estimates will be improved. When the true QTL has a small effect, using outbred population experiment design with large family size is the optimal mapping strategy.
Identifying Gene Interaction Enrichment for Gene Expression Data
Jigang Zhang,Jian Li,Hong-Wen Deng
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0008064
Abstract: Gene set analysis allows the inclusion of knowledge from established gene sets, such as gene pathways, and potentially improves the power of detecting differentially expressed genes. However, conventional methods of gene set analysis focus on gene marginal effects in a gene set, and ignore gene interactions which may contribute to complex human diseases. In this study, we propose a method of gene interaction enrichment analysis, which incorporates knowledge of predefined gene sets (e.g. gene pathways) to identify enriched gene interaction effects on a phenotype of interest. In our proposed method, we also discuss the reduction of irrelevant genes and the extraction of a core set of gene interactions for an identified gene set, which contribute to the statistical variation of a phenotype of interest. The utility of our method is demonstrated through analyses on two publicly available microarray datasets. The results show that our method can identify gene sets that show strong gene interaction enrichments. The enriched gene interactions identified by our method may provide clues to new gene regulation mechanisms related to the studied phenotypes. In summary, our method offers a powerful tool for researchers to exhaustively examine the large numbers of gene interactions associated with complex human diseases, and can be a useful complement to classical gene set analyses which only considers single genes in a gene set.
Immune Evasion of Human Lung Carcinoma Cell A549 Suppressed by Human Lymphoma Cell Jurkat via Fas/FasL Pathway
Hongmei WANG,Guoqiang ZHANG,Jigang DAI,Jiaxin MIN
Chinese Journal of Lung Cancer , 2010,
Abstract: Background and objective Tumor escape from the host immune system has been a major problem in immunotherapy of human malignancies. FasL/Fas-induced apoptosis plays an important role in various immunological processes. The aim of this study is to investigate the immune evasion in human lung carcinoma cell A549 induced by human lymphoma cell Jurkat via Fas/FasL pathway. Methods Jurkat cells and A549 cells were co-cultured at different proportions. The apoptotic rates of A549 cells were determined by flow cytometry (FCM). Protein levels of Fas, FasL and Caspase-8 in A549 cells were detected by Western blot. Results Survival rates of A549 cells gradually decreased and apoptotic rates of A549 cells were significantly enhanced along with ratio increasing between Jurkat and A549. Meanwhile, the protein levels of Fas and Caspase-8 gradually increased in A549 cells, and the protein levels of FasL had no significant difference in all groups. Conclusion The Jurkat cells might decrease the survival rates of A549 cells and enhanced its apoptosis and immune evasion partly via Fas/FasL pathway.
Transient Charge and Energy Balance in Graphene Induced by Ultrafast Photoexcitation
Junhua Zhang,Joerg Schmalian,Tianqi Li,Jigang Wang
Physics , 2013, DOI: 10.1088/0953-8984/25/31/314201
Abstract: Ultrafast optical pump-probe spectroscopy measurement on monolayer graphene observes significant optical nonlinearities. We show that strongly photoexcited graphene monolayers with 35 fs pulses quasi-instantaneously build up a broadband, inverted Dirac fermion population. Optical gain emerges and directly manifests itself via a negative conductivity at the near-infrared region for the first 200fs, where stimulated emission completely compensates absorption loss in the graphene layer. To quantitatively investigate this transient, extremely dense photoexcited Dirac-fermion state, we construct a two-chemical-potential model, in addition to a time-dependent transient carrier temperature above lattice temperature, to describe the population inverted electronic state metastable on the time scale of tens of femtoseconds generated by a strong exciting pulse. The calculated transient optical conductivity reveals a complete bleaching of absorption, which sets the saturation density during the pulse propagation. Particularly, the model calculation reproduces the negative optical conductivity at lower frequencies in the states close to saturation, corroborating the observed femtosecond stimulated emission and optical gain in the wide near-infrared window.
Post-transient relaxation in graphene after an intense laser pulse
Junhua Zhang,Tianqi Li,Jigang Wang,Joerg Schmalian
Physics , 2013, DOI: 10.1140/epjst/e2013-01920-2
Abstract: High intensity laser pulses were recently shown to induce a population inverted transient state in graphene [T. Li et al. Phys. Rev. Lett. 108, 167401 (2012)]. Using a combination of hydrodynamic arguments and a kinetic theory we determine the post-transient state relaxation of hot, dense, population inverted electrons towards equilibrium. The cooling rate and charge-imbalance relaxation rate are determined from the Boltzmann-equation including electron-phonon scattering. We show that the relaxation of the population inversion, driven by inter-band scattering processes, is much slower than the relaxation of the electron temperature, which is determined by intra-band scattering processes. This insight may be of relevance for the application of graphene as an optical gain medium.
基于CA的溢油扩散时空过程模拟及敏感性分析
Spatio-Temporal Simulation and Sensitivity Analysis of Oil Spill CA Model

张亦汉, 乔纪纲
ZHANG Yihan
, QIAO Jigang

- , 2017, DOI: 10.13203/j.whugis20140719
Abstract: 为了解决传统溢油元胞自动机(cellular automata,CA)模型难以获得的模型参数问题,引入逻辑回归方法到溢油CA模型中,并构建基于逻辑回归的溢油CA模型。该模型仅需要设置起始影像和影响因子(包括海风、洋流、距离、温度与盐度)等,便可以获取模型参数并模拟出溢油扩散范围的动态变化过程。将模型应用到深海溢油实验中以验证本模型在海上溢油模拟情况,结果表明模拟结果的总精度为96.6%,Kappa系数达0.899,能够准确地模拟出溢油扩散范围。通过参数敏感性分析可发现,温度与盐度因子对模型的影响最弱,其次是距离因子。对溢油扩散影响最为显著的是海风和洋流因子。若忽略海风与洋流的影响,模拟结果与观测结果将产生较大的偏差,并无法呈现出溢油扩散中的漂移等特征
Knockdown of Snail Sensitizes Pancreatic Cancer Cells to Chemotherapeutic Agents and Irradiation
Kejun Zhang,Xuelong Jiao,Xiaoyi Liu,Bingyuan Zhang,Jigang Wang,Quan Wang,Yan Tao,Dianliang Zhang
International Journal of Molecular Sciences , 2010, DOI: 10.3390/ijms11124891
Abstract: The prognosis of patients with pancreatic cancer remains poor; only patients with small tumors and complete resection have a chance of a complete cure. Pancreatic cancer responds poorly to conventional therapies, including chemotherapy and irradiation. Snail is a transcription factor that has been associated with anti-apoptotic and chemoresistant properties in pancreatic cancer cells. In this study, we investigated whether knockdown of Snail suppresses growth of and/or sensitizes pancreatic cancer cells to chemotherapeutic agents and irradiation through induction of apoptosis. An adeno-associated virus vector was used to deliver Snail siRNA and knockdown Snail expression in untreated pancreatic cancer cells and in pancreatic cancer cells treated with chemotherapeutic agents or γ-irradiation. Our data indicate that our adeno-associated virus vector can efficiently deliver Snail siRNA into PANC-1 cells both in vitro and in vivo, resulting in the knockdown of Snail expression at the mRNA and protein levels. We further show that knockdown of Snail expression results in potent growth suppression of pancreatic cancer cells and suppresses xenograft tumor growth in vivo through induction of apoptosis. Finally, knockdown of Snail expression significantly sensitizes pancreatic cancer cells to chemotherapeutic agents and γ-irradiation through induction of apoptosis. In conclusion, our?findings indicate that Snail is an important modulator of therapeutic responses of pancreatic cancer cells and is potentially useful as a sensitizer in pancreatic cancer therapy.
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