Qian Guo

Abstract A new explicit split-step Milstein method for solving linear Itô stochastic differential equations (SDEs) with a constant time delay is introduced. The Itô-Taylor expansion is employed to prove the strong convergence, which inproves the convergence results of known split-step methods for stochastic delay differential equations (SDDEs). Numerical experiments confirm the theoretical results. Key words stochastic delay differential equation; Milstein scheme; split-step; strong convergence

Abstract Ultra-fine polymer fibers, obtained by electrospinning, have a wide range of potential applications such as fluid filtration, biomedicine, catalyst supports, drug delivery, tissue engineering, nanowires, to just say few. Yet theoretical modeling the spinning process remains a bottleneck severely hampering further improvement in both quality and efficiency. This paper establishes a mathematical model to explore the physics behind electrospinning.

We consider a procedure for cancer therapy which consists of injecting replication-competent viruses into the tumor. The viruses infect tumor cells, replicate inside them, and eventually cause their death. As infected cells die, the viruses inside them are released and then proceed to infect adjacent tumor cells. However, a major factor influencing the efficacy of virus agents is the immune response that may limit the replication and spread of the replication-competent virus. The immune response is cytokine-mediated.

Increasing evidence suggests that lysosomal cysteine proteases cathepsins contribute to the progression of cell apoptosis. Here we found that apoptosis of ovarian cancer cells OV-90 triggered by TNF was cathepsin B-depended. Two cathepsin B binding proteins, bikunin and TSRC1, were identified by yeast two-hybrid method and the interactions were confirmed in vitro and in vivo. Overexpression of bikunin could suppress TNF-induced apoptosis of OV-90 cells, and TSRC1 overexpression had an opposite effect on apoptosis. The presented results suggest that cathepsin B and its interacting proteins, bikunin and TSRC1, are involved in the apoptotic pathway of ovarian cancer cells.

Abstract We consider a mathematical model describing the evolution of a vascular tumour in response to traditional chemotherapy. The model is a free boundary problem for a system of partial differential equations governing intratumoural drug concentration, cancer cell density and blood vessel density. Tumour cells consist of two types of competitive cells that have different proliferation rates and different sensitivities to drugs. The balance between cell proliferation and death generates a velocity field that drives tumour cell movement. The ...

There has been little work on the optimal configuration of biohydrogen production reactors. This paper describes three-dimensional computational fluid dynamics (CFD) simulations of gas-liquid flow in a laboratory-scale continuous stirred-tank reactor used for biohydrogen production. To evaluate the role of hydrodynamics in reactor design and optimize the reactor configuration, an optimized impeller design has been constructed and validated with CFD simulations of the normal and optimized impeller over a range of speeds and the numerical results were also validated by examination of residence time distribution. By integrating the CFD simulation with an ethanol-type fermentation process experiment, it was shown that impellers with different type and speed generated different flow patterns, and hence offered different efficiencies for biohydrogen production. The hydrodynamic behavior of the optimized impeller at speeds between 50 and 70 rev/min is most suited for economical biohydrogen production.

... 3, XU Yan-kai,CHEN Xi(a.Department of Automation,b.Center for Intelligent and Networked Systems,Tsinghua University,Beijing 100084,China.;Reinforcement ... 4, LIN Xiang-ze1,2, ZOU Yun1, LI Shi-hua3, QIAN Yan-ping4 (1. School of Automation, Nanjing University of Science ...

In order to increase the hydrogen yield from glucose, hydrogen production by immobilized Rhodopseudomonas faecalis RLD-53 using soluble metabolites from ethanol fermentation bacteria Ethanoligenens harbinense B49 was investigated. The soluble metabolites from ...

In this paper, we present rigorous simulation tools: a lattice-based simple reactive sphere model, an off-lattice bead-spring Monte Carlo model, and a molecular dynamics model. These tools accurately describe the static and dynamic behaviors of perfluoropolyether films consistent with experimental findings (scanning microellipsometry and surface energy measurements). These are suitable for the description of the fundamental mechanisms of film dewetting

SBA-15-supported iron phosphate (FePO4) has been characterized with XRD, TEM, Raman spectroscopy and H2-TPR, and studied for the partial oxidation of CH4 with O2. The characterizations suggest that the FePO4 species with loading amount lower than 40wt.% ...

... This reduc-tion can be partially accomplished via the lubricant nanofilm on the top of the carbon overcoat to build up a robust tribological reliability. ... The nanofilm dynamics, including the self-diffusion and relaxation, which depend on the Manuscript received October 16, 2003. ...

A procedure of separating the primary-and scatter-dose components in therapeutic photon beams is examined. It is based on the observation that the scatter-dose component is proportional to the variable z= rd/(r+ d), where r and d are beam radius and depth in ...

Theoretical studies of reconstructed GaAs(tOO) surfaces using first principle calculations Guo-Xin Qian, Richard M. Martin, and DJ Chadi Xerox Palo Alto Research Center, Palo Alto, California 94304 (Received 10 February 1987; accepted 1 April 1987) Full and one-half ...

... J; STRUB, R; TODOROV, T; TURCHETTA, R; VAN HOVE, P; VINTACHE, D; ZGHICHE, A; AGERON, M; AUGUSTIN, J; BATY, C; BAULIEU, G; BEDJIDIAN, M; BLAHA, J; BONNEVAUX, A; BOUDOUL, G; BRUNET, P; CHABANAT, E; CHABERT, E; CHIERICI, R; CHOROWICZ, V ...

The inhibition of nitric oxide (NO) by hypercholesterolemia may be mediated, in part, by interactions with caveolin-1 (Cav-1). Because of the facilitatory effects of statins on endothelial function and the adverse effects of rapamycin (RAPA) on plasma lipids, we compared the effects of simvastatin (SMV) and RAPA on endothelial NO synthase (eNOS) and Cav-1 protein expression and phosphorylation in the aortas of apolipoprotein E (Apo-E) knockout (-/-) mice. Apo-E -/- mice (n = 38) fed a high-cholesterol diet were given SMV (100 mg/kg/day po), RAPA (3 mg/kg/day ip), or no treatment for 10 weeks. Blood was drawn for serum lipid analysis, and protein was extracted for Western immunoblotting. Selected aortic specimens from 2 animals in each group were examined by histology and immunohistochemistry. The data are expressed as the mean +/- SEM and compared by the Student t test and ANOVA. Significance was established as P < .05. Lipid levels at 10 weeks were similar in the 3 groups except for higher triglyceride levels in RAPA-treated animals. eNOS expression was highest in RAPA-treated mice, but the p-eNOS to eNOS protein expression ratio was significantly greater in the SMV treatment group compared to both RAPA and controls (P < .05). Both Cav-1 and p-Cav-1 expression was significantly lower in the SMV-treated animals (P < .05) compared to mice treated with RAPA. Although eNOS expression was greatest in the RAPA-treated mice, the expression of p-eNOS was similar in the RAPA- and SMV-treated animals. The increase in eNOS induced by RAPA and the inverse relationship between p-eNOS and Cav-1 protein expression observed with SMV treatment suggest different mechanisms for the regulation of aortic eNOS expression in Apo-E mice by these 2 agents.

DNA polymorphism among 34 Chinese Auricularia auricula cultivars was analyzed using inter-simple sequence repeat (ISSR) and sequence-related amplified polymorphism (SRAP) markers. Thirty ISSR primers amplified a total of 129 DNA fragments of which 125 (96.9%) were polymorphic, whereas 11 SRAP primer combinations amplified 154 fragments of which 148 (96.1%) were polymorphic. Both methods were highly effective in discriminating among the test strains. Phylogenetic trees constructed on the basis of ISSR, SRAP, and combined ISSR/SRAP analyses using the Unweighted Pair-group Method with Arithmetic Averages (UPGMA) method distributed the 34 strains into four or five major groups. Clustering analysis based on all the three data sets indicated a high level of genetic diversity among A. auricula, although the combined ISSR/SRAP data were more concordant with the main agronomic characters of strains and their geographical centers of cultivation. Our findings will facilitate future A. auricula breeding programs and the development of bioactive products from this commercially important medicinal mushroom.

Recent clinical studies in China showed that As2O3 is an effective and relatively safe drug in the treatment of acute promyelocytic leukemia (APL). We found previously that As2O3 can trigger apoptosis of APL cell line NB4 cells, which is associated with downregulation of bcl-2 gene expression and modulation of PML-RAR alpha chimeric protein. To further understand the mechanisms of this alternative therapy for APL, we investigated in this report the effects of a wide range of concentrations of As2O2 on cultured primary APL cells, all-trans retinoic acid (ATRA)-susceptible (NB4 cells) and ATRA-resistant (MR2 subclone) APL cell lines. The results indicated that As2O3 had dose-dependent dual effects on APL cells: inducing preferentially apoptosis at relatively high concentrations (0.5 to 2 micromol/L) and inducing partial differentiation at low concentrations (0.1 to 0.5 micromol/L). The rapid modulation and degradation of PML-RAR alpha proteins, which was induced by As2O3 at 0.1 to 2 micromol/L, could contribute to these two effects. Bone marrow and peripheral blood examination showed that myelocyte-like cells, probably as a result of partial in vivo differentiation, and degenerative cells increased after 2 to 3 weeks of continuous in vivo As2O3 treatment when leukemic promyelocytes decreased. In conclusion, combination of induction of apoptosis and partial differention could be the main cellular mechanisms of As2O3 in the treatment of APL, and PML-RAR alpha could play an important role in determining the specific effects of As2O3 on APL cells.

Research in autophagy continues to accelerate,(1) and as a result many new scientists are entering the field. Accordingly, it is important to establish a standard set of criteria for monitoring macroautophagy in different organisms. Recent reviews have described the range of assays that have been used for this purpose.(2,3) There are many useful and convenient methods that can be used to monitor macroautophagy in yeast, but relatively few in other model systems, and there is much confusion regarding acceptable methods to measure macroautophagy in higher eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers of autophagosomes versus those that measure flux through the autophagy pathway; thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from fully functional autophagy that includes delivery to, and degradation within, lysosomes (in most higher eukaryotes) or the vacuole (in plants and fungi). Here, we present a set of guidelines for the selection and interpretation of the methods that can be used by investigators who are attempting to examine macroautophagy and related processes, as well as by reviewers who need to provide realistic and reasonable critiques of papers that investigate these processes. This set of guidelines is not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to verify an autophagic response.

... Soc. 105, 624–625. 6. Woerdenbag, HJ, Pras, N., Chan, NG, Bang, BT, Bos, R., Van Uden, W., Van, YP, Boi, NV, Batterman, S., and Lugt, CB (1994) Artemisinin, related sesquiterpenes, and essential oil in Artemisia annua during a vegetation period in Vietnam. Planta Med. ...

... All chemicals were of reagent grade. 2.2. Chemical and monosaccharide analysis of psyllium husk. Protein content was analyzed by NA2100 Nitrogen and Protein Analyzer (Strada Rivoltana, Milan, Italy) using the factor of 6.24 to convert measured nitrogen to protein. ...

Molecular rheology of perfluoropolyether (PFPE) systems is particularly important in designing effective lubricants that control the friction and wear in tribological applications. Using the coarse-grained, bead-spring model, equilibrium molecular dynamics based on the Langevin equation in a quiescent flow was first employed to examine the nanostructure of PFPE. Further, by integrating the modified Langevin equation and imposing the Lees-Edwards boundary condition, nonequilibrium molecular dynamics of steady shear was investigated. We observe that the shear viscosity of PFPE system depends strongly on molecular architecture (e.g., molecular weight and endgroup functionality) and external conditions (e.g., temperature and shear rate). Our study of the flow activation energy/entropy and their correlations with nanostructure visualization showed that the PFPE structure was substantially modified.

Molecular dynamics simulations with the Langevin equation using a coarse-grained, bead-spring model were performed to investigate the dynamic properties of nanoscale lubricant films. The simulated spreading profiles of lubricant nanofilms are in qualitative agreement ...

The DS18B20 is a 1-WIRE digital thermometer of DALLAS Semiconductor, It can realize direct digital putput and examination, and has strong control function, long distance transmission, strong antijamming ability, miniature, low power consumption and so on. ...

Abstract In the paper, two kinds of equations of block elastic motion are established: the equation with rotation in the entire block and homogeneous strain and the equation with rotation in the entire block and linear strain. Using the velocities of GPS sites located in the ...