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Search Results: 1 - 10 of 129730 matches for " Tse-Yao Wang "
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Effect of co-exposure to nickel and particulate matter on insulin resistance and mitochondrial dysfunction in a mouse model
Xu Xiaohua,Rao Xiaoquan,Wang Tse-Yao,Jiang Silis Y
Particle and Fibre Toxicology , 2012, DOI: 10.1186/1743-8977-9-40
Abstract: Background It has been well recognized that toxicity of fine ambient air particulate matter (PM2.5) may depend on its chemical constituents, including components such as soluble metals that may theoretically exert distinctive effects. We have recently demonstrated an important effect of PM2.5 on metabolic function. Since transition metals, such as nickel (Ni), represent an important component of exposure in certain environments, and may significantly influence the toxicity of inhalational exposure, we investigated the effects of Ni as a variable component of ambient PM2.5 exposure. Methods Male ApoE knockout mice were exposed to filtered air (FA), fine-sized nickel sulfate particles alone (Ni) at 0.44 μg/m3, concentrated ambient air PM2.5 (CAPs) at a mean of 70 μg/m3, or CAPs+Ni in Tuxedo, NY, 6 hours/day, 5 days/week, for 3 months. Results Exposure to Ni, irrespective of co-exposure to CAPs, resulted in body weight gain, while exposure to CAPs+Ni significantly enhanced fasting glucose and worsened insulin resistance measures (HOMA-IR), when compared with exposure to CAPs alone. CAPs+Ni exposure induced a significant decrease in phosphorylation of AMP-activated protein kinase (AMPK) α. Exposure to Ni or CAPs+Ni significantly induced microcirculatory dysfunction and increased monocytic cell infiltration into lung and adipose, and decreased uncoupling protein 1 expression at gene and protein levels and several brown adipocyte-specific genes in adipose tissue. Conclusions Ni exposure has effects on metabolic and inflammatory parameters that are comparable to that of CAPs. Additionally, Ni synergistically exacerbates CAPs-induced adverse effects on some of, but not all of, these parameters, that may be mediated via the AMPK signaling pathway. These findings have important implications for inhaled transition metal toxicity that may exert synergistic effects with other PM2.5 components.
Inflammatory Response to Fine Particulate Air Pollution Exposure: Neutrophil versus Monocyte
Xiaohua Xu, Silis Y. Jiang, Tse-Yao Wang, Yuntao Bai, Mianhua Zhong, Aixia Wang, Morton Lippmann, Lung-Chi Chen, Sanjay Rajagopalan, Qinghua Sun
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071414
Abstract: Objectives Studies have shown that chronic exposure to ambient fine particulate matter (less than 2.5 μm in aerodynamic diameter, PM2.5) pollution induces insulin resistance through alterations in inflammatory pathways. It is critical to study how the immune system responds to this stimulant, which has been linked to cardiovascular and autoimmune diseases, but few studies have been focused on such involvement of both neutrophils and monocytes in a timely manner. We hypothesized that the neutrophil was involved in the inflammatory response to air pollution. Methods and Results C57BL/6 mice were exposed to PM2.5 or filtered air (6 hours/day, 5 days/week) for 5, 14, and 21 days, respectively, in Columbus, OH. At the end of each of the exposure periods, we investigated the inflammatory response through flow cytometry, histology, intravital microscopy, and real-time PCR. PM2.5-exposed mice demonstrated a significant inflammatory response after 5 days of exposure. In the lung tissue and bronchoalveolar lavage fluid, monocytes/macrophages showed a transient response, while neutrophils showed a cumulative response. In addition, exposure to PM2.5 resulted in elevation of the monocyte chemoattractant protein 1 (MCP-1) cytokine, a monocyte/macrophage attractant in blood, at an early stage of exposure. Conclusions These findings suggest that PM2.5 exposure induces the inflammatory responses from both macrophages and neutrophils involvement.
Exercise Protects against Diet-Induced Insulin Resistance through Downregulation of Protein Kinase Cβ in Mice
Xiaoquan Rao, Jixin Zhong, Xiaohua Xu, Brianna Jordan, Santosh Maurya, Zachary Braunstein, Tse-Yao Wang, Wei Huang, Sudha Aggarwal, Muthu Periasamy, Sanjay Rajagopalan, Kamal Mehta, Qinghua Sun
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0081364
Abstract: Physical exercise is an important and effective therapy for diabetes. However, its underlying mechanism is not fully understood. Protein kinase Cβ (PKCβ) has been suggested to be involved in the pathogenesis of obesity and insulin resistance, but the role of PKCβ in exercise-induced improvements in insulin resistance is completely unknown. In this study, we evaluated the involvement of PKCβ in exercise-attenuated insulin resistance in high-fat diet (HFD)-fed mice. PKCβ-/- and wild-type mice were fed a HFD with or without exercise training. PKC protein expression, body and tissue weight change, glucose and insulin tolerance, metabolic rate, mitochondria size and number, adipose inflammation, and AKT activation were determined to evaluate insulin sensitivity and metabolic changes after intervention. PKCβ expression decreased in both skeletal muscle and liver tissue after exercise. Exercise and PKCβ deficiency can alleviate HFD-induced insulin resistance, as evidenced by improved insulin tolerance. In addition, fat accumulation and mitochondrial dysfunction induced by HFD were also ameliorated by both exercise and PKCβ deficiency. On the other hand, exercise had little effect on PKCβ-/- mice. Further, our data indicated improved activation of AKT, the downstream signal molecule of insulin, in skeletal muscle and liver of exercised mice, whereas PKCβ deficiency blunted the difference between sedentary and exercised mice. These results suggest that downregulation of PKCβ contributes to exercise-induced improvement of insulin resistance in HFD-fed mice.
Two-Dimensional Topological Insulator State and Topological Phase Transition in Bilayer Graphene
Zhenhua Qiao,Wang-Kong Tse,Hua Jiang,Yugui Yao,Qian Niu
Physics , 2011, DOI: 10.1103/PhysRevLett.107.256801
Abstract: We show that gated bilayer graphene hosts a strong topological insulator (TI) phase in the presence of Rashba spin-orbit (SO) coupling. We find that gated bilayer graphene under preserved time-reversal symmetry is a quantum valley Hall insulator for small Rashba SO coupling $\lambda_{\mathrm{R}}$, and transitions to a strong TI when $\lambda_{\mathrm{R}} > \sqrt{U^2+t_\bot^2}$, where $U$ and $t_\bot$ are respectively the interlayer potential and tunneling energy. Different from a conventional quantum spin Hall state, the edge modes of our strong TI phase exhibit both spin and valley filtering, and thus share the properties of both quantum spin Hall and quantum valley Hall insulators. The strong TI phase remains robust in the presence of weak graphene intrinsic SO coupling.
Tunneling states in graphene heterostructures consisting of two different graphene superlattices
Li-Gang Wang,Yuen-Chi Tse,Shi-Yao Zhu
Physics , 2011, DOI: 10.1063/1.3573492
Abstract: We have theoretically investigated the properties of electronic transport in graphene heterostructures, which are consisted of two different graphene superlattices with one-dimensional periodic potentials. It is found that such heterostructures possess an unusual tunneling state occurring inside the original forbidden gaps, and the electronic conductance is greatly enhanced and Fano factor is strongly suppressed near the energy of the tunneling state. Finally we present the matching condition of the impedance of the pseudospin wave for occuring the tunneling state by using the Bloch-wave expansion method.
Topological phases in gated bilayer graphene: Effects of Rashba spin-orbit coupling and exchange field
Zhenhua Qiao,Xiao Li,Wang-Kong Tse,Hua Jiang,Yugui Yao,Qian Niu
Physics , 2012, DOI: 10.1103/PhysRevB.87.125405
Abstract: We present a systematic study on the influence of Rashba spin-orbit coupling, interlayer potential difference and exchange field on the topological properties of bilayer graphene. In the presence of only Rashba spin-orbit coupling and interlayer potential difference, the band gap opening due to broken out-of-plane inversion symmetry offers new possibilities of realizing tunable topological phase transitions by varying an external gate voltage. We find a two-dimensional $Z_2$ topological insulator phase and a quantum valley Hall phase in $AB$-stacked bilayer graphene and obtain their effective low-energy Hamiltonians near the Dirac points. For $AA$ stacking, we do not find any topological insulator phase in the presence of large Rashba spin-orbit coupling. When the exchange field is also turned on, the bilayer system exhibits a rich variety of topological phases including a quantum anomalous Hall phase, and we obtain the phase diagram as a function of the Rashba spin-orbit coupling, interlayer potential difference, and exchange field.
Quantum Anomalous Hall Effect in Single-layer and Bilayer Graphene
Wang-Kong Tse,Zhenhua Qiao,Yugui Yao,A. H. MacDonald,Qian Niu
Physics , 2011, DOI: 10.1103/PhysRevB.83.155447
Abstract: The quantum anomalous Hall effect can occur in single and few layer graphene systems that have both exchange fields and spin-orbit coupling. In this paper, we present a study of the quantum anomalous Hall effect in single-layer and gated bilayer graphene systems with Rashba spin-orbit coupling. We compute Berry curvatures at each valley point and find that for single-layer graphene the Hall conductivity is quantized at $\sigma_{xy} = 2e^2/h$, with each valley contributing a unit conductance and a corresponding chiral edge state. In bilayer graphene, we find that the quantized anomalous Hall conductivity is twice that of the single-layer case when the gate voltage $U$ is smaller than the exchange field $M$, and zero otherwise. Although the Chern number vanishes when $U > M$, the system still exhibits a quantized valley Hall effect, with the edge states in opposite valleys propagating in opposite directions. The possibility of tuning between different topological states with an external gate voltage suggests possible graphene-based spintronics applications.
Quantum Anomalous Hall Effect in Graphene from Rashba and Exchange Effects
Zhenhua Qiao,Shengyuan A. Yang,Wanxiang Feng,Wang-Kong Tse,Jun Ding,Yugui Yao,Jian Wang,Qian Niu
Physics , 2010, DOI: 10.1103/PhysRevB.82.161414
Abstract: We investigate the possibility of realizing quantum anomalous Hall effect in graphene. We show that a bulk energy gap can be opened in the presence of both Rashba spin-orbit coupling and an exchange field. We calculate the Berry curvature distribution and find a non-zero Chern number for the valence bands and demonstrate the existence of gapless edge states. Inspired by this finding, we also study, by first principles method, a concrete example of graphene with Fe atoms adsorbed on top, obtaining the same result.
Study on Spatial Econometrics of Level Spatial Data of Knowledge Spillover Effect in Industrial Industry in Guangdong Province  [PDF]
Yao Wang
Open Journal of Business and Management (OJBM) , 2018, DOI: 10.4236/ojbm.2018.63043
This paper uses an econometric model of hierarchical data space to do empirical research on the knowledge spillover effect of industrial industries in Guangdong Province. Specifically, three-dimensional panel data (regions, industries, and time) of 21 prefecture-level cities and 31 industrial industries in Guangdong Province from 2005 to 2016 were used and spatial correlation, time factors, and hierarchical nesting effects were taken into consideration to establish hierarchical data. The spatial econometric model uses an industrial structure to empirically analyze the impact of the knowledge spillover effect of the industrial industry in Guangdong on its economic development.
Drude-Interband Coupling, Screening, and the Optical Conductivity of Doped Bilayer Graphene
Wang-Kong Tse,A. H. MacDonald
Physics , 2009,
Abstract: We present a theory of the influence of band renormalization and excitonic electron-electron interaction effects on the optical conductivity $\sigma(\omega)$ of doped bilayer graphene. Using the Keldysh formalism, we derive a kinetic equation from which we extract numerical and approximate analytic results for $\sigma(\omega)$. Our calculations reveal a previously unrecognized mechanism which couples the Drude and interband response and renormalizes the plasmon frequency, and suggest that screening must play an essential role in explaining the weakly renormalized conductivity seen in recent experiments.
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