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Search Results: 1 - 10 of 18502 matches for " Xuelu Han "
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Neuroprotective Effects of Ginkgo Biloba Extract (GbE) on Oxygen-Glucose Deprivation (OGD) in PC12 Cells  [PDF]
Chunli Mei, Xuelu Han, Jing Zhang, Ling Gao, Huimin Liu
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.510B030
Abstract:

Ischemic cerebrovascular disease is a global health problem. According to the World Health Organization, ischemic stroke is actually the most common cause of death in the world. Ginkgo biloba extract (GbE) is a traditional Chinese medicine for angina pectoris. Ginkgo biloba plays a role in expanding blood vessels, increasing coronary and cerebral blood flow, preventing platelet aggregation, inhibiting thrombosis, and improving the microcirculation. In the present study, we investigated the mechanisms involved in the neuroprotective effects of GbE in a model of hypoxic-ischemic brain disease. We used NGF(100 ng/ml for 6 days)and OGD(5% CO2and 95% N2, 1 mmol/l NaS2O4insugar-free DMEM for 16 h) to stimulate PC12 cells and convert them into neurons in order to establish an ischemia model. The results showed that PC12 cells transformed into cells that looked like neurons and that MAP2 was up-regulated in NGF-treated PC12 cells. Cell apoptosis was found to be up-regulated after NGF stimulation and OGD. The apoptosis rate after 16 hours of OGD was 19.44%. GbE (50ng/ml) reduces apoptosis rate to 11.35%. These results may help to show that NGF treatment can be combined with OGD to establish anin vitromodel of acute ischemic brain damage. In the present study, we find that GbE effectively increases the survival rate of PC12 cells and relieves OGD damage. These results suggest that GbE has the neuroprotective effects of ischemic brain damage.


Integrated Assessment of Heavy Metal Pollution in the Surface Sediments of the Laizhou Bay and the Coastal Waters of the Zhangzi Island, China: Comparison among Typical Marine Sediment Quality Indices
Wen Zhuang, Xuelu Gao
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0094145
Abstract: The total concentrations and chemical forms of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in the surface sediments of the Laizhou Bay and the surrounding marine area of the Zhangzi Island (hereafter referred to as Zhangzi Island for short) were obtained and multiple indices and guidelines were applied to assess their contamination and ecological risks. The sedimentary conditions were fine in both of the two studied areas according to the marine sediment quality of China. Whereas the probable effects level guideline suggested that Ni might cause adverse biological effects to occur frequently in some sites. All indices used suggested that Cd posed the highest environmental risk in both the Laizhou Bay and the Zhangzi Island, though Cd may unlikely be harmful to human and ecological health due to the very low total concentrations. The enrichment factor (EF) showed that a substantial portion of Cr was delivered from anthropogenic sources, whereas the risk assessment code (RAC) indicated that most Cr was in an inactive state that it may not have any adverse effect either. Moreover, the results of EF and geoaccumulation index were consistent with the trend of the total metal concentrations except for Cd, while the results of RAC and potential ecological risk factor did not follow the same trend of their corresponding total metal concentrations. We also evaluated the effects of using different indices to assess the environmental impact of these heavy metals.
Unique Structure and Dynamics of the EphA5 Ligand Binding Domain Mediate Its Binding Specificity as Revealed by X-ray Crystallography, NMR and MD Simulations
Xuelu Huan, Jiahai Shi, Liangzhong Lim, Sayantan Mitra, Wanlong Zhu, Haina Qin, Elena B. Pasquale, Jianxing Song
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0074040
Abstract: The 16 EphA and EphB receptors represent the largest family of receptor tyrosine kinases, and their interactions with 9 ephrin-A and ephrin-B ligands initiate bidirectional signals controlling many physiological and pathological processes. Most interactions occur between receptor and ephrins of the same class, and only EphA4 can bind all A and B ephrins. To understand the structural and dynamic principles that enable Eph receptors to utilize the same jellyroll β-sandwich fold to bind ephrins, the VAPB-MSP domain, peptides and small molecules, we have used crystallography, NMR and molecular dynamics (MD) simulations to determine the first structure and dynamics of the EphA5 ligand-binding domain (LBD), which only binds ephrin-A ligands. Unexpectedly, despite being unbound, the high affinity ephrin-binding pocket of EphA5 resembles that of other Eph receptors bound to ephrins, with a helical conformation over the J–K loop and an open pocket. The openness of the pocket is further supported by NMR hydrogen/deuterium exchange data and MD simulations. Additionally, the EphA5 LBD undergoes significant picosecond-nanosecond conformational exchanges over the loops, as revealed by NMR and MD simulations, but lacks global conformational exchanges on the microsecond-millisecond time scale. This is markedly different from the EphA4 LBD, which shares 74% sequence identity and 87% homology. Consequently, the unbound EphA5 LBD appears to comprise an ensemble of open conformations that have only small variations over the loops and appear ready to bind ephrin-A ligands. These findings show how two proteins with high sequence homology and structural similarity are still able to achieve distinctive binding specificities through different dynamics, which may represent a general mechanism whereby the same protein fold can serve for different functions. Our findings also suggest that a promising strategy to design agonists/antagonists with high affinity and selectivity might be to target specific dynamic states of the Eph receptor LBDs.
Solving Large Scale Nonlinear Equations by a New ODE Numerical Integration Method  [PDF]
Tianmin Han, Yuhuan Han
Applied Mathematics (AM) , 2010, DOI: 10.4236/am.2010.13027
Abstract: In this paper a new ODE numerical integration method was successfully applied to solving nonlinear equations. The method is of same simplicity as fixed point iteration, but the efficiency has been significantly improved, so it is especially suitable for large scale systems. For Brown’s equations, an existing article reported that when the dimension of the equation N = 40, the subroutines they used could not give a solution, as compared with our method, we can easily solve this equation even when N = 100. Other two large equations have the dimension of N = 1000, all the existing available methods have great difficulties to handle them, however, our method proposed in this paper can deal with those tough equations without any difficulties. The sigularity and choosing initial values problems were also mentioned in this paper.
Solving Load Flow Problems of Power System by Explicit Pseudo-Transient Continuation (E-ψtc) Method  [PDF]
Tianmin Han, Yuhuan Han
Energy and Power Engineering (EPE) , 2016, DOI: 10.4236/epe.2016.82009
Abstract: This paper is a further study of two papers [1] and [2], which were related to Ill-Conditioned Load Flow Problems and were published by IEEE Trans. PAS. The authors of this paper have some different opinions, for example, the 11-bus system is not an ill-conditioned system. In addition, a new approach to solve Load Flow Problems, E-ψtc, is introduced. It is an explicit method; solving linear equations is not needed. It can handle very tough and very large systems. The advantage of this method has been fully proved by two examples. The authors give this new method a detailed description of how to use it to solve Load Flow Problems and successfully apply it to the 43-bus and the 11-bus systems. The authors also propose a strategy to test the reliability, and by solving gradient equations, this new method can answer if the solution exists or not.
New conception in continuum theory of constitutive equation for anisotropic crystalline polymer liquids  [PDF]
Shifang Han
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.29116
Abstract: A new continuum theory of the constitutive equation of co-rotational derivative type is developed for anisotropic viscoelastic fluid—liquid crystalline (LC) polymers. A new concept of simple anisotropic fluid is introduced. On the basis of principles of anisotropic simple fluid, stress behaviour is described by velocity gradient tensor and spin tensor instead of the velocity gradient tensor in the classic Leslie—Ericksen continuum theory. Analyzing rheological nature of the fluid and using tensor analysis a general form of the constitutive equ- ation of co-rotational type is established for the fluid. A special term of high order in the equation is introduced by author to describe the sp- ecial change of the normal stress differences which is considered as a result of director tumbling by Larson et al. Analyzing the experimental results by Larson et al., a principle of Non- oscillatory normal stress is introduced which leads to simplification of the problem with relaxation times. The special behaviour of non- symmetry of the shear stress is predicted by using the present model for LC polymer liquids. Two shear stresses in shear flow of LC polymer liquids may lead to vortex and rotation flow, i.e. director tumbling in the flow. The first and second normal stress differences are calculated by the model special behaviour of which is in agree- ment with experiments. In the research, the com- putational symbolic manipulation such as computer software Maple is used. For the anisotropic viscoelastic fluid the constitutive equation theory is of important fundamental significance.
Using Integrating Method to Teach Biochemical Pharmacy Technology  [PDF]
Chunchao Han
Creative Education (CE) , 2010, DOI: 10.4236/ce.2010.13021
Abstract: An integrating method to teach Biochemical Pharmacy Technology was developed to help students understand the technology to produce biochemical pharmacy well in this paper. By the integrating method, students can compare the main content of the biochemical pharmacy and the technology to produce them. Students were encouraged to demonstrate the connection and difference of the various biochemical pharmacies. The results showed that the performance of students with integrating method is significantly better than that of students without integrating method (p < 0.05). In conclusion, integrating method can enhance students’ performance on Biochemical Pharmacy Technology.
A new constitutive theory for extrusion-extensional flow of anisotropic liquid crystalline polymer fluid  [PDF]
Shifang Han
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.34040
Abstract: A new continuum theory of the constitutive equation of co-rotational derivative type was developed by the author for anisotropic viscoelastic fluid-liquid crystalline (LC) polymers (S.F. Han, 2008, 2010) . This paper is a continuation of the recent publication [1] to study extrusion-extensional flow of the fluid. A new concept of simple anisotropic fluid is introduced. On the basis of anisotropic simple fluid, stress behavior is described by velocity gradient tensor F and spin tensor W instead of the velocity gradient tensor D in the classic Leslie?Ericksen continuum theory. A special form of the constitutive equation of the co-rotational type is established for the fluid. Using the special form of the constitutive equation in components a computational analytical theory of the extrusion-extensional flow is developed for the LC polymer liquids - anisotropic viscoelastic fluid. Application of the constitutive theory to the flow is successful in predicting bifurcation of elongational viscosity and contraction of extrudate for LC polymer liquids–anisotropic viscoelastic fluid. The contraction of extrudate of LC polymer liquids may be associated with the stored elastic energy conversion into that necessary for bifurcation of elongational viscosity in extrusion extensional flow of the fluid.
An Equation of State for Nonaqueous Electrolyte Solutions  [PDF]
Zheng Han
Advances in Chemical Engineering and Science (ACES) , 2012, DOI: 10.4236/aces.2012.24061
Abstract: A two parameters equation of state (EOS) for nonaqueous electrolyte solutions system has been developed. The equation is in terms of Helmholtz free energy and incorporated with results of low density expansion of non-primitive mean spherical approximation. The EOS was tested for experimental data reported in literatures of 9 nonaqueous single electrolyte solutions of which the temperature was 298.15 K, and it also has a good predictive capability for nonaqueous electrolyte solutions at different temperature in this work. The comparisons with EOSs published earlier by other researchers in literatures are carried out in detail.
New conception in continuum theory of constitutive equation for anisotropic crystalline polymer liquids  [PDF]
Shifang Han
Natural Science (NS) , 2010, DOI: 10.4236/ns.2009.29116
Abstract: A new continuum theory of the constitutive equation of co-rotational derivative type is developed for anisotropic viscoelastic fluid—liquid crystalline (LC) polymers. A new concept of simple anisotropic fluid is introduced. On the basis of principles of anisotropic simple fluid, stress behaviour is described by velocity gradient tensor and spin tensor instead of the velocity gradient tensor in the classic Leslie—Ericksen continuum theory. Analyzing rheological nature of the fluid and using tensor analysis a general form of the constitutive equ- ation of co-rotational type is established for the fluid. A special term of high order in the equation is introduced by author to describe the sp- ecial change of the normal stress differences which is considered as a result of director tumbling by Larson et al. Analyzing the experimental results by Larson et al., a principle of Non- oscillatory normal stress is introduced which leads to simplification of the problem with relaxation times. The special behaviour of non- symmetry of the shear stress is predicted by using the present model for LC polymer liquids. Two shear stresses in shear flow of LC polymer liquids may lead to vortex and rotation flow, i.e. director tumbling in the flow. The first and second normal stress differences are calculated by the model special behaviour of which is in agree- ment with experiments. In the research, the com- putational symbolic manipulation such as computer software Maple is used. For the anisotropic viscoelastic fluid the constitutive equation theory is of important fundamental significance.
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