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Search Results: 1 - 10 of 23419 matches for " Yancheng Zheng "
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Adsorption Properties of Gemini and Monomeric Cationic Surfactants on Sandstone and Silica Nanoparticles  [PDF]
Wenjun Xie, Ge Xu, Yancheng Zheng, Shining Chen, Zhuo Yang, Borui Li
Open Journal of Yangtze Oil and Gas (OJOGas) , 2018, DOI: 10.4236/ojogas.2018.33018
Abstract: The surface modification of pore throat by adsorption of surfactants is thought to have a positive effect on water flooding in low and ultralow permeability reservoirs. In this paper, Gemini cationic surfactants, containing 12 and 16 carbon alkyl chains(ethanediyl-1,2-bis(dimethyl dodecyl ammonium bromide) and ethanediyl-1,2-bis(dimethyl cetyl ammonium bromide), referred to as GC12 and GC16) and hexadecyl trimethyl ammonium bromide (CTAB) were used as modifying agents to investigate the effects of the surfactant concentration, adsorption time and temperature on static adsorption onto the surface of sandstone and silica nano particles (NPS). The results show that the equilibrium adsorption amount of GC16 on sandstone and NPS is higher than that of GC12 on sandstone and NPS with the same initial concentration of 0.225 mmol/L in solution at 45°C. It is found that the adsorption amounts of GC12 and GC16 decrease as the raise of temperature. The adsorption rate of surfactant on sandstone surface is slower than that of NPS. The equilibrium adsorption time of these surfactants on sandstone is 20 h, while the time of NPS is only 2 h. At 55°C, the static saturation absorption amount of GC12 is 210.56 μmol/g on NPS and 117.67 μmol/g on sandstone, while the amounts of CTAB on sandstone and NPS under static conditions are 1.18 times and 1.46 times of GC12, respectively. Considering the number of tail chain in a molecule of surfactant, the packing densities of Gemini surfactants on solid surface are higher than that of the single-tail surfactant (CTAB). Therefore, the adsorption rate and amount of surfactant are affected by the specific surface of solid particles, charged density, tail chain number and length of the cationic group.
Reconstruction of the Township Government Functions in the Process of Urbanization
Yancheng Wang
Research Journal of Applied Sciences, Engineering and Technology , 2012,
Abstract: In this study, we get the results that the rural economic environment and the change of social environment for township government proposed the new task, the transformation of township government functions to put forward new requirements. The township government efforts to adjust its economic management function and social management function the scope and content, in order to promote the development of rural productivity, pushing the undertakings in progress. Therefore, the current urbanization background to the standing committees of the countryside should target function in guide to promote economic development, strengthen the township town planning and management and promote rural grassroots democracy construction and cultural construction, maintenance of urban and rural social stability and social fair four aspects.
Tyrosine Induces Anthocyanin Biosynthesis in Arabidopsis thaliana  [PDF]
Zhou Zhou, Tiantian Zhi, Yan Liu, Yancheng Chen, Chunmei Ren
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.53045
Abstract:


Anthocyanins are widely found in plants and are responsible for the purple coloration of plants. Anthocyanin biosynthesis is induced by environmental stresses, plant hormones, sugar, and so on. Tyrosine (Tyr) is the precursor of melanin that exits in both animals and plants. However, until now it has been unknown whether Tyr induces anthocyanin biosynthesis. In this study, the seedlings of Arabidopsis thaliana were treated with exogenous Tyr and then the anthocyanin accumulation was determined. The results showed that Tyr induced anthocyanin accumulation in Arabidopsis thaliana in a dose-dependent manner. Furthermore, the expression of the late anthocyanin biosynthetic genes including DFR, LDOX, and UF3GT, and the transcription factor genes PAP1, PAP2, and EGL3 was induced by Tyr. Taken together, these results demonstrated that Tyr is able to induce anthocyanin accumulation and suggested

The acid cleaning method of labware for trace element analysis in snow and ice samples

YaPing Liu,ShuGui Hou,YanCheng Zhang,

寒旱区科学 , 2009,
Abstract: Acid cleaning processes were performed on a class 100 laminar flow clean bench assembled inside a class 1000 clean room. The ultrapure water was produced by Millipore RO (Reverse Osmosis) and Milli-Q water purification systems. The three purity grades of nitric acid used for cleaning include Merck reagent grade HNO3, Fisher "TraceMetal" grade HNO3, and the purest Fisher "Optima" grade HNO3. The various bottles, containers and other labware, which are in contact with the samples, are made of low-density polyethylene (LDPE) and FEP or PFA Teflon materials. The acid cleaning procedures of the bottles and other containers follow a successive four times cleaning through immersion in increasing purity of nitric acid baths at different concentrations during four weeks. The first acid bath is performed at room temperature, but the following three acid baths are heated on ceramic hotplates with a surface temperature of 45 °C. In order to verify the efficiency of the acid cleaning method, cleaned bottles underwent a blank determination procedure using ELAN 6100 inductively coupled plasma spectrometry (ICP-MS). Results show that most measured trace elements are not detected and the elements detected are at very low concentrations. The blank values are comparable with that of bottles cleaned at Korea Polar Research Institute (KOPRI). Although the acid cleaning method is developed mainly for reliable measurements of trace elements in snow and ice samples, it can also be used for investigations of trace elements in other environmental samples.
Anomalous quantum glass of bosons in a random potential in two dimensions
Yancheng Wang,Wenan Guo,Anders W. Sandvik
Physics , 2011, DOI: 10.1103/PhysRevLett.114.105303
Abstract: We present a quantum Monte Carlo study of the "quantum glass" phase of the 2D Bose-Hubbard model with random potentials at filling $\rho=1$. In the narrow region between the Mott and superfluid phases the compressibility has the form $\kappa \sim {\rm exp}(-b/T^\alpha)+c$ with $\alpha <1$ and $c$ vanishing or very small. Thus, at $T=0$ the system is either incompressible (a Mott glass) or nearly incompressible (a Mott-glass-like anomalous Bose glass). At stronger disorder, where a glass reappears from the superfluid, we find a conventional highly compressible Bose glass. On a path connecting these states, away from the superfluid at larger Hubbard repulsion, a change of the disorder strength by only $10\%$ changes the low-temperature compressibility by more than four orders of magnitude, lending support to two types of glass states separated by a phase transition or a sharp cross-over.
Pair supersolid of the extended Bose-Hubbard model with atom-pair hopping on the triangular Lattice
Wanzhou Zhang,Yancheng Wang,Wenan Guo
Physics , 2012, DOI: 10.1103/PhysRevB.88.174515
Abstract: We systematically study an extended Bose-Hubbard model with atom hopping and atom-pair hopping in the presence of a three-body constraint on the triangular lattice. By means of large-scale Quantum Monte Carlo simulations, the ground-state phase diagram are studied. We find a continuous transition between the atomic superfluid phase and the pair superfluid when the ratio of the atomic hopping and the atom-pair hopping is adapted. We then focus on the interplay among the atom-pair hopping, the on-site repulsion and the nearest-neighbor repulsion. With on-site repulsion present, we observe first order transitions between the Mott Insulators and pair superfluid driven by the pair hopping. With the nearest-neighbor repulsion turning on, three typical solid phases with 2/3, 1 and 4/3-filling emerge at small atom-pair hopping region. A stable pair supersolid phase is found at small on-site repulsion. This is due to the three-body constraint and the pair hopping, which essentially make the model a quasi hardcore boson system. Thus the pair supersolid state emerges basing on the order-by-disorder mechanism, by which hardcore bosons avoid classical frustration on the triangular lattice. The transition between the pair supersolid and the pair superfluid is first order, except for the particle-hole symmetric point. We compare the results with those obtained by means of mean-field analysis.
Antioxidant Activities of Plumbagin and Its Cu (II) Complex
Mingxiong Tan,Yancheng Liu,Xujian Luo,Zhenfeng Chen,Hong Liang
Bioinorganic Chemistry and Applications , 2011, DOI: 10.1155/2011/898726
Abstract: Plumbagin and its Cu (II) complex [Cu (plumbagin)2]·H2O have been synthesized, and their antioxidant activities towards the inhibitory effect on DPPH free radical, reducing power, total antioxidant capacity, and inhibition on lipid peroxidation were investigated. Plumbagin and its Cu (II) complex were found to exhibit scavenging activities on DPPH radical with the inhibitory rate of 41% and 24%, respectively. The reducing power of plumbagin was outstanding at the concentrations of 1.0, 1.5, and 2.0?mg/mL, compared to Cu (II) complex and synthetic antioxidant 2,6-di-ter-butyl-4-methylphenol (BHT); the highest level reached 1.333 for plumbagin and 0.581 for Cu (II) complex. Also, the inhibition on lipid peroxidation of plumbagin was higher than that of Cu (II) complex and BHT, 46.4% for plumbagin and 24.5% for Cu (II) complex. The results give a strong impact for designing anticancer drugs, combined with their potential cytotoxic and antioxidant activities, which can be targeted selectively against cancer cells and increase their therapeutic index and additional advantages over other anticancer drugs. 1. Introduction Recently, a large number of metal complexes have been designed and tested for anticancer activity and for supportive therapy in cancer patients, including the anticancer drugs doxorubicin, mitoxantrone, bleomycin, and hydroxyurea [1–3]. There is a major debate at present that natural products with diverse bioactivities are becoming an important source of potential (pro)drug chelators [4, 5]. Many naturally occurring molecules such as flavonoids, phenols, and quinones have metal chelating properties, cytotoxic, and antioxidant properties, including the inhibitory effect on free radicals and other damaging oxygen activated products such as the hydroxyl radical, superoxide, hydrogen peroxide, and lipid peroxides [6, 7]. Thus, the prospect of designing chelating prodrugs can be targeted selectively and activated against cancer cells combined with their potential cytotoxic and antioxidant activities increasing their therapeutic index and provides additional advantages over other anticancer drugs [8–10]. Our earlier studies have reported the synthesis and anticancer activities of plumbagin (Scheme 1) and its Cu (II) complex (Scheme 2). Plumbagin structurally derived from naphthoquinone was extracted from Plumbago zeylanica L, a Chinese traditional medicine. It was found that both plumbagin and its Cu (II) complex exhibited significant antitumor activities against seven human tumour cell lines (BEL-7404, NCI-H460, CNE-2, 786-O, MCF-7, HCT-116, and
The role of CopG mediated DNA bending on the regulation of the σ54-dependent promoters in E. coli
Yancheng Chen,Ence Yang,Zhenfeng Liu,Zhexian Tian,Yiping Wang
Chinese Science Bulletin , 2006, DOI: 10.1007/s11434-006-0934-6
Abstract: In order to investigate the role of DNA bending on the regulation of σ54-dependent promoters, we introduced the CopG binding site between the enhancer-like element and the core promoter of glnAp2, nifLp and glnHp2, without changing the distance in between. The expression activities of these homologous promoters were either activated or repressed by the CopG-induced DNA bending in E. coli. In this case, similar regulatory pattern (either activated or repressed) could be observed, when the bending centers from CopG are in integral DNA helixes interval, while opposite regulatory pattern could be observed, when the bending centers from CopG are in integral plus a half DNA helixes interval. These results suggested that CopG-induced DNA bending can exert regulatory effects on the transcription of σ54-dependent promoters probably by altering the relative DNA helix phase of 54 RNA polymerase and NtrC.
Polymorphism of the methylenetetrahydrofolate reductase gene association with homocysteine and ischemic stroke in type 2 diabetes
Sun Jia-Zhong,Xu Yancheng,Lu Hongyun,Zhu Yilian
Neurology India , 2009,
Abstract: Background : Ischemic stroke is a frequent heterogeneous multifactorial disease. A number of genetic mutations and environmental factors have been implicated. A polymorphism in the gene for methylenetetrahydrofolate reductase (MTHFR) has been reported to be associated with hyperhomocysteinemia a risk for atherosclerotic vascular diseases. Aim : A cross-sectional study was performed to determine the relationship between the gene polymorphism for MTHFR and ischemic stroke in type 2 diabetes mellitus. Materials and Methods : Of the 215 unrelated patients with type 2 diabetes mellitus recruited, 119 patients had ischemic stroke, Control group included 142 healthy subjects. The genotype of the subjects for the C677T polymorphism of MTHFR was analyzed by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) followed by HinfI digestion. Plasma total homocysteine (Hcy) levels were measured using high-performance liquid chromatography (HPLC) with fluorescence detection. Results : The genotype distribution did not differ between the control subjects and type 2 diabetic patients (P > 0.05). Plasma homocysteine levels were markedly higher in diabetic patients with TT genotype than those with CC or CT genotype (P > 0.05). Ischemic stroke was more frequently observed in type 2 diabetic patients with the TT genotype than in those with the CT and CC genotype (odds ratio=4.04, 95% CI=1.95-8.34, P=0.0036). Logistic regression analysis revealed that the C677T mutation of MTHFR gene was independently associated with ischemic stroke in type 2 diabetes. Conclusion : MTHFR C677T gene polymorphism associated with a predisposition to hyperhomocysteinemia could constitute a useful predictive marker for ischemic stroke in type 2 diabetic Chinese patients.
Irinotecan/cisplatin versus Etoposide/cisplatin for Patients with Extensive Stage Small Cell Lung Cancer: A Systematic Review
Nan YAO,Lei JIANG,Kehu YANG,Yancheng YE
Chinese Journal of Lung Cancer , 2009,
Abstract: Background and objective It is unclear whether etoposide/cisplatin (EP) regimen is the optimal chemotherapy regimen in the treatment patients with extensive small cell lung cancer (SCLC), this study was aimed to evaluate the efficacy and safety of patients with extensive SCLC treated with irinotecan/cisplatin (IP) versus EP. Methods We searched EMBASE, PubMed, the Cochrane Library, China journal full-text database (CJFD), Chinese scientific journal full-text database (CSJD), Chinese biomedicine literature database (CBM) for randomized controlled trials comparing IP with EP regimens. Two reviewers independently assessed the quality of included studies and extracted data. We analyzed the data using Review Manager (version 5.0). Results Four randomized controlled trials totaling 1 180 patients were included. The results of meta analysis were as follows: there was no significant difference between IP regimen and EP regimens in one year survive rate (RR=1.22, 95%CI: 0.97-1.54), two year survive rate (RR=2.26, 95%CI: 0.46-11.21). There was significant difference between IP regimen and EP regimens in overall response rate (RR=1.13, 95%CI: 1.03-1.25), grade 3/4 neutropenia (RR=0.48, 95%CI: 0.34-0.69), thrombopenia (RR=0.23, 95%CI: 0.15-0.36), grade 3 anemia (RR=0.55, 95%CI: 0.40-0.77), grade 3/4 diarrhea (RR=9.56, 95%CI: 4.91-18.59), grade 3 nausea/vomiting (RR=1.70, 95%CI: 1.19-2.43). Conclusion There is no significant difference between IP group and EP group with regard to one year survive rate, two year survive rate, but IP regimen improves reponse rate. IP regimen has less hematologic & greater gastrointestinal toxicity compared with EP, EP regimen remain the main standard chemotherapy in the treatment extensive small cell lung cancer due to cheapness, they still need to be confirmed by randomized controlled trials.
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