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Search Results: 1 - 10 of 78257 matches for " Weikang Chen "
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Protective Effect against Hydroxyl-induced DNA Damage and Antioxidant Activity of Radix Glycyrrhizae (Liquorice Root)
Xican Li,Weikang Chen,Dongfeng Chen
Advanced Pharmaceutical Bulletin , 2013, DOI: 10.5681/apb.2013.028
Abstract: Purpose: As a typical Chinese herbal medicine, Radix Glycyrrhizae (RG) possesses various pharmacological effects involved in antioxidant ability. However, its antioxidant has not been explored so far. The aim of the study was to investigate its antioxidant ability, then further discuss the antioxidant mechanism. Methods: RG was extracted by ethanol to obtain ethanolic extract of Radix Glycyrrhizae (ERG). ERG was then determined by various antioxidant methods, including DNA damage assay, DPPH assay, ABTS assay, Fe3+-reducing assay and Cu2+-reducing assay. Finally, the contents of total phenolics and total flavonoids were analyzed by spectrophotometric methods. Results: Our results revealed that ERG could effectively protect against hydroxyl-induced DNA damage (IC50 517.28±26.61μg/mL). In addition, ERG could scavenge DPPH· radical (IC50165.18±6.48μg/mL) and ABTS+ radical (IC507.46±0.07μg/mL), reduce Fe3+ (IC50 97.23±2.88 μg/mL) and Cu2+ (IC50 59.21±0.18 μg/mL). Chemical analysis demonstrated that the contents of total phenolics and flavonoids in ERG were 111.48±0.88 and 218.26±8.57 mg quercetin/g, respectively. Conclusion: Radix Glycyrrhizae can effectively protect against hydroxyl-induced DNA damage. One mechanism of protective effect may be radical-scavenging which is via donating hydrogen atom (H·), donating electron (e). Its antioxidant ability can be mainly attributed to the flavonoids or total phenolics.
Molecular dynamics simulations of the evaporation of particle-laden droplets
Weikang Chen,Joel Koplik,Ilona Kretzschmar
Physics , 2012, DOI: 10.1103/PhysRevE.87.052404
Abstract: We use molecular dynamics simulations to study the evaporation of particle-laden droplets on a heated surface. The droplets are composed of a Lennard-Jones fluid containing rigid particles which are spherical sections of an atomic lattice, and heating is controlled through the temperature of an atomistic substrate. We observe that sufficiently large (but still nano-sized) particle-laden drops exhibit contact line pinning, measure the outward fluid flow field which advects particle to the drop rim, and find that the structure of the resulting aggregate varies with inter-particle interactions. In addition, the profile of the evaporative fluid flux is measured with and without particles present, and is also found to be in qualitative agreement with earlier theory. The compatibility of simple nanoscale calculations and micron-scale experiments indicates that molecular simulation may be used to predict aggregate structure in evaporative growth processes.
Velocity slip on curved surfaces
Weikang Chen,Rui Zhang,Joel Koplik
Physics , 2013, DOI: 10.1103/PhysRevE.89.023005
Abstract: The Navier boundary condition for velocity slip on flat surfaces, when expressed in tensor form, is readily extended to surfaces of any shape. We test this assertion using molecular dynamics simulations of flow in channels with flat and curved walls and for rotating cylinders and spheres, all for a wide range of solid-liquid interaction strengths. We find that the slip length as conventionally measured at a flat wall in Couette flow is the same as that for all other cases with curved and rotating boundaries, provided the atomic interactions are the same and boundary shape is properly taken into account. These results support the idea that the slip length is a material property, transferable between different flow configurations.
Evaluation of Hepatic Cystic Echinococcosis’ CT image in Xinjiang Uygur Autonomous Region based on Kolmogorov Complexity Model  [PDF]
Jingjing Zhou, Murat Hamit, Abdugheni Kutluk, Chuanbo Yan, Li Li, Jianjun Chen, Yanting Hu, Dewei Kong, Weikang Yuan
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.410B015
Abstract:

Designing and developing computer-assisted image processing techniques to help doctors improve their diagnosis has received considerable interests over the past years. In this paper, we used the kolmogorov complexity model to analyze the CT images of the healthy liver and multiple daughter hydatid cysts. Before the complexity characteristic calculating, the image preprocessing methods had been used for image standardization. From the kolmogorov complexity model, complexity characteristic were calculated in order to quantify the complexity, between healthy liver and multiple daughter hydatid cysts. Then we use statistical method to analyze the complexity characteristic of those two types of images. Our preliminary results show that the complexity characteristic has statistically significant (p<0.05) to analyze these two types CT images, between the healthy liver and the multiple daughter hydatid cysts. Furthermore, the result leads us to the conclusion that the kolmogorov complexity model could use for analyze the hydatid disease and will also extend the analysis the other lesions of liver.

Relationship of Post-Stroke Aphasic Types with Sex, Age and Stroke Types  [PDF]
Jingfan Yao, Zaizhu Han, Yanli Song, Lei Li, Yun Zhou, Weikang Chen, Chunxue Wang, Yongjun Wang, Yumei Zhang
World Journal of Neuroscience (WJNS) , 2015, DOI: 10.4236/wjns.2015.51004
Abstract: Aim:To explore what is the relationship of the types of post-stroke aphasia with sex, age andstroke types.Methods:Retrospective analysis was administrated on data of 421 patients with acutestroke. Western battery aphasia was used to measure aphasiac type and aphasia quotient (AQ)score. The patients were divided into three age groups: young, middle-aged and elderly. The stroketypes were classified into cerebral infraction (CI) and intracerebral hemorrhage (ICH). Results: All subjects were right-handed, which males and females accounted for 69.60% and 30.40%, respectively. There were 116 cases of Broca’s aphasia (85 males), 35 cases of Wernicke’s aphasia (20 males),15 cases of conductive aphasia (10 males), 63 cases of transcortical motor aphasia (50 males), 11 cases of transcortical sensory aphasia (8 males), 27 cases of transcortical combined aphasia (13 males), 73 cases of anomic aphasia (47 males) and 81 cases of global aphasia (60 males). Male patients (69.60%) have a significantly higher morbidity of aphasia than that of females (30.40%) after stroke (χ2
Relationship of Post-Stroke Aphasic Types with Sex, Age and Stroke Types  [PDF]
Jingfan Yao, Zaizhu Han, Yanli Song, Lei Li, Yun Zhou, Weikang Chen, Yongmei Deng, Yongjun Wang, Yumei Zhang
World Journal of Neuroscience (WJNS) , 2015, DOI: 10.4236/wjns.2015.51004
Abstract: Aim: To explore what is the relationship of the types of post-stroke aphasia with sex, age and stroke types. Methods: Retrospective analysis was administrated on data of 421 patients with acute stroke. Western battery aphasia was used to measure aphasiac type and aphasia quotient (AQ) score. The patients were divided into three age groups: young, middle-aged and elderly. The stroke types were classified into cerebral infraction (CI) and intracerebral hemorrhage (ICH). Results: All subjects were right-handed, which males and females accounted for 69.60% and 30.40%, respectively. There were 116 cases of Broca’s aphasia (85 males), 35 cases of Wernicke’s aphasia (20 males), 15 cases of conductive aphasia (10 males), 63 cases of transcortical motor aphasia (50 males), 11 cases of transcortical sensory aphasia (8 males), 27 cases of transcortical combined aphasia (13 males), 73 cases of anomic aphasia (47 males) and 81 cases of global aphasia (60 males). Male patients (69.60%) have a significantly higher morbidity of aphasia than that of females (30.40%) after stroke (χ2 = 11.57
Breaking the EOS-Gravity Degeneracy with Masses and Pulsating Frequencies of Neutron Stars
Weikang Lin,Bao-An Li,Lie-Wen Chen,De-Hua Wen,Jun Xu
Physics , 2013, DOI: 10.1088/0954-3899/41/7/075203
Abstract: A thorough understanding of many astrophysical phenomena associated with compact objects requires reliable knowledge about both the equation of state (EOS)of super-dense nuclear matter and the theory of strong-field gravity simultaneously because of the EOS-gravity degeneracy. Currently, variations of the neutron star (NS) mass-radius correlation from using alternative gravity theories are much larger than those from changing the NS matter EOS within known constraints. At least two independent observables are required to break the EOS-gravity degeneracy. Using model EOSs for hybrid stars and a Yukawa-type non-Newtonian gravity, we investigate both the mass-radius correlation and pulsating frequencies of NSs. While the maximum mass of NSs increases, the frequencies of the $f$, $p_1$, $p_2$, and $w_I$ pulsating modes are found to decrease with the increasing strength of the Yukawa-type non-Newtonian gravity, providing a useful reference for future determination simultaneously of both the strong-field gravity and the supranuclear EOS by combining data of x-ray and gravitational wave emissions of neutron stars.
Studies on Modelizing the Effects of Immobilized Cell Distribution on Kinetics
固定化细胞分布对动力学影响的模型化研究

Wei Dongzhi Yuan Weikang Chen Minheng,
魏东芝
,袁渭康,陈敏恒,袁中一

生物工程学报 , 1996,
Abstract: A nonuniform distribution model of immobilized cells was established by the studies on immobilized Gluconobacter oxydans and Bacillus cereus living cells. It was compared with uniform distribution model. Effects of the two typical cell distribution on substrate distribution in immobilized biocatalyst, effective rate factor and selective yield were discussed. No obvious difference was observed between the effects of uniform cell distribution and that of nonuniform cell distribution on kinetics of immobilized G. oxydans and B. cereus living cells, which was then confirmed in experiments. The conclusion is also fit for the studies on kinetics of other immobilized biocatalyst system.
Ceramide Mediates Ox-LDL-Induced Human Vascular Smooth Muscle Cell Calcification via p38 Mitogen-Activated Protein Kinase Signaling
Lizhen Liao, Qin Zhou, Yan Song, Weikang Wu, Huimin Yu, Sheng Wang, Yanling Chen, Meihong Ye, Lihe Lu
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0082379
Abstract: Vascular calcification is associated with significant cardiovascular morbidity and mortality, and has been demonstrated as an actively regulated process resembling bone formation. Oxidized low density lipoprotein (Ox-LDL) has been identified as a regulatory factor involved in calcification of vascular smooth muscle cells (VSMCs). Additionally, over-expression of recombinant human neutral sphingomyelinase (N-SMase) has been shown to stimulate VSMC apoptosis, which plays an important role in the progression of vascular calcification. The aim of this study is to investigate whether ceramide regulates Ox-LDL-induced calcification of VSMCs via activation of p38 mitogen-activated protein kinase (MAPK) pathway. Ox-LDL increased the activity of N-SMase and the level of ceramide in cultured VSMCs. Calcification and the osteogenic transcription factor, Msx2 mRNA expression were reduced by N-SMase inhibitor, GW4869 in the presence of Ox-LDL. Usage of GW4869 inhibited Ox-LDL-induced apoptosis in VSMCs, an effect which was reversed by C2-ceramide. Additionally, C2-ceramide treatment accelerated VSMC calcification, with a concomitant increase in ALP activity. Furthermore, C2-ceramide treatment enhanced Ox-LDL-induced VSMC calcification. Addition of caspase inhibitor, ZVAD-fmk attenuated Ox-LDL-induced calcification. Both Ox-LDL and C2-ceramide treatment increased the phosphorylation of p38 MAPK. Inhibition of p38 MAPK by SB203580 attenuated Ox-LDL-induced calcification of VSMCs. These data suggest that Ox-LDL activates N-SMase-ceramide signaling pathway, and stimulates phosphorylation of p38 MAPK, leading to apoptosis in VSMCs, which initiates VSMC calcification.
Translational Chinese Medicine: A Way for Development of Traditional Chinese Medicine  [PDF]
Xuegang Sun, Donglan Lin, Weikang Wu, Zhiping Lv
Chinese Medicine (CM) , 2011, DOI: 10.4236/cm.2011.24029
Abstract: Translational Chinese medicine is one of the latest developing fields in traditional Chinese medicine. In this paper, we discuss the “3 w” namely, “what is”, “why to advance”, “how to carry out” and the significance of translational Chinese medicine. To overcome the innate drawbacks of traditional Chinese medicine (TCM), the basic theory of TCM had better be refreshed. The safety and efficacy of classic formulae and therapy experience of TCM should be evaluated based on strict quality control and reaffirmed with evidence based medicine. The significance of translational Chinese medicine is to transform Chinese medicine into a balanced, personalized medicine with sound safety, good efficacy and strict quality control.
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