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Search Results: 1 - 10 of 37114 matches for " Lixia Zhao "
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Cheeger's constant and the first eigenvalue of a closed Finsler manifold
Wei Zhao,Lixia Yuan
Mathematics , 2013,
Abstract: In this paper, we consider Cheeger's constant and the first eigenvalue of the nonlinear Laplacian on closed Finsler manifolds. Being based on these, we establish Cheeger's inequality and Buser's inequality for closed Finsler manifolds.
Some formulas of Santaló type in Finsler geometry and its applications
LiXia Yuan,Wei Zhao
Mathematics , 2014,
Abstract: In this paper, we establish two Santal\'o type formulas for general Finsler manifolds. As applications, we derive a universal lower bound for the first eigenvalue of the nonlinear Laplacian, two Croke type isoperimetric inequalities, and a Yamaguch type finiteness theorem in Finser geometry.
Ultraviolet irradiation induced oxidative stress and response of antioxidant system in an intertidal macroalgae Corallina o cinalis L.

Lixia Li,Jiqiang Zhao,Xuexi Tang,

环境科学学报(英文版) , 2010,
Abstract: The response of the antioxidant defense system of an intertidal macroalgae Corallina o cinalis L. to di erent dosages of UV-B irradiation was investigated. Results showed that superoxide dimutase (SOD) and peroxidase (POX) increased and then maintained at a relatively stable level when subjected to UV-B irradiation. Catalase (CAT) activity under medium dosage of UV-B irradiation (Muv) and high dosage of UV-B irradiation (Huv) treatments were significantly decreased. Ascorbate peroxidase (APX) activity first remained unaltered and then increased in Huv treatment. In addition, the assay on isozymes was carried out using non-denaturing polyacrylamide gel electrophoresis (PAGE). The activities of some SOD isoforms were altered by UV-B. Two new bands (POX V and POX VII) appeared upon exposure to all three UV-B dosages. CAT III activity was increased by low dosage of UV-B irradiation (Luv), whereas CAT III and CAT IV disappeared when the alga was exposed to Muv and Huv. Two bands of APX (APX VI and APX VII) were increased and a new band (APX X) was observed under Huv exposure. H2O2 and thiobarbituric acid reacting substance (TBARS) increased under Muv and Huv treatments. Overall, UV-B protection mechanisms are partly inducible and to a certain extent su cient to prevent the accumulation of damage in C. o cinalis.
Study on superoxide and hydroxyl radicals generated in indirect electrochemical oxidation by chemiluminescence and UV-Visible spectra

Zhang Botao,Zhao Lixia,Lin Jinming,

环境科学学报(英文版) , 2008,
Abstract: The generation and transformation of radicals on the cathode of indirect electrochemical oxidation were studied by chemiluminescence (CL) and UV-visible spectra in the reactor with a salt bridge that connected the separated chambers. The CL intensity of 4 × 10-9 mol/L luminol on the cathode with bubbling oxygen was about seven times that of the intensity without it, which was because of the generation of reactive oxygen species (ROS). The existence of ROS, especially the generation of the superoxide radical, could be affirmed by the fact that the CL intensity of 4 × 10--9 mol/L 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo1,2-a]pyrazin-3-one with bubbling oxygen was about four times that of the intensity without it. However, there was no chemiluminescence on the anode under the same condition. The change in the UV-visible spectra of nitro blue tetrazolium and N,N-dimethyl-4-nitrosoaniline at the cathode chamber affirmed the transformation from oxygen to superoxide and hydroxyl radicals. The mechanism of the superoxide and hydroxyl radical generation and transformation on the cathode was discussed with the help of the experimental results and relative references.
LED Modulation Characteristics in a Visible-Light Communication System  [PDF]
Yanrong Pei, Shaoxin Zhu, Hua Yang, Lixia Zhao, Xiaoyan Yi, Junxi Junxi Wang, Jinmin Li
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.32B034
Abstract:

This paper conducts a research on modulation characteristics of blue light-emitting diodes (LEDs) used in a visible-light communication (VLC) system. Through analysis of the modulation characteristics of LEDs with different emitting sizes, we find that there is a similar linear relationship between LED’s 3dB bandwidth and the operation current density. This experiment also shows that high series resistance is one major issue that limits our LED's modulation speed. To further improve the LED bandwidth, the resistance can be reduced by optimizing device layout as well as reducing material bulk resistance. Clearly, this study provides an approach to increase the modulation bandwidth of GaN-based LEDs for VLC systems.

STAT1 Regulates Human Glutaminase 1 Promoter Activity through Multiple Binding Sites in HIV-1 Infected Macrophages
Lixia Zhao, Yunlong Huang, Jialin Zheng
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076581
Abstract: Mononuclear phagocytes (MP, macrophages and microglia), the main targets of HIV-1 infection in the brain, play a pathogenic role in HIV-associated neurocognitive disorders (HAND) through the production and release of various soluble neurotoxic factors including glutamate. We have previously reported that glutaminase (GLS), the glutamate-generating enzyme, is upregulated in HIV-1 infected MP and in the brain tissues of HIV dementia individuals, and that HIV-1 or interferon-α (IFN-α) regulates human glutaminase 1 (GLS1) promoter through signal transducer and activator of transcription 1 (STAT1) phosphorylation in macrophages. However, there are multiple putative STAT1 binding sites in human GLS1 promoter, the exact molecular mechanism of how HIV-1 or IFN-α regulates human GLS1 promoter remains unclear. To further study the function of the putative STAT1 binding sites, we mutated the sequence of each binding site to ACTAGTCTC and found that six mutants (mut 1,3,4,5,7,8) had significantly higher promoter activity and two mutants (mut 2 and mut 6) completely lost the promoter activity compared with the wild type. To determine whether sites 2 and 6 could interfere with other inhibitory sites, particularly the nearby inhibitory sites 3 and 5, we made double mutants dmut 2/3 and dmut 5/6, and found that both the double mutants had significantly higher activity than the wild type, indicating that sites 3 and 5 are critical inhibitory elements, while sites 2 and 6 are excitatory elements. ChIP assay verified that STAT1 could bind with sites 2/3 and 5/6 within human GLS1 promoter in IFN-α stimulated or HIV-1-infected monocyte-derived macrophages. Interestingly, we found that rat Gls1 promoter was regulated through a similar way as human GLS1 promoter. Together, our data identified critical elements that regulate GLS1 promoter activity.
Application of Polymers in Low Permeability Formations  [PDF]
Juan Zhao, Caili Dai, Guang Yang, Jian Zhang, Hui Yang, Xinsheng Xue, Xiaodong Kang, Lixia Li
Journal of Materials Science and Chemical Engineering (MSCE) , 2015, DOI: 10.4236/msce.2015.35005
Abstract: For low-permeability sandstone reservoir with big channel, we researched the novel deep profile method alternative injection of anionic and cationic polymer. Evaluating various factors on adsorption capacity through lab test, the results show that with the increase of temperature, the adsorption capacity decreases and the cationic polymer is easier to be absorbed. With the increase of salinity, adsorption time or polymer concentration, the adsorption capacity increases. The adsorption equilibrium concentration of cationic polymer is 1500 mg/L; adsorption equilibrium time is 8 h. The adsorption equilibrium concentration of anionic polymer is 1000 mg/L; adsorption equilibrium time is 6 h. Physical simulation experiment shows that alternative injection of anionic and cationic polymer is better than injection of single polymer, and preferential injection of cationic polymer is better than preferential injection of anionic polymer. With the increase of injection rounds, sealing capacity gets better, but in view of cost, the rounds should not be more than 3. The profile control technique can obviously enhanced oil recovery, and water displacement recovery increases 41%. 2 wells were tested successfully in Henan Oilfield in June 2010. Approximate 154.47 tons of incremental oil was obtained with 2% water-cut decrease.
Hilbert Boundary Value Problem with an Unknown Function on Arbitrary Infinite Straight Line  [PDF]
Lixia Cao
Advances in Pure Mathematics (APM) , 2013, DOI: 10.4236/apm.2013.32033
Abstract:

We consider a Hilbert boundary value problem with an unknown parametric function on arbitrary infinite straight line passing through the origin. We propose to transform the Hilbert boundary value problem to Riemann boundary value problem, and address it by defining symmetric extension for holomorphic functions about an arbitrary straight line passing through the origin. Finally, we develop the general solution and the solvable conditions for the Hilbert boundary value problem.

Some Properties of a Kind of Singular Integral Operator with Weierstrass Function Kernel  [PDF]
Lixia Cao
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.48166
Abstract:

We considered a kind of singular integral operator with Weierstrass function kernel on a simple closed smooth curve in a fundamental period parallelogram. Using the method of complex functions, we established the Bertrand Poincaré formula for changing order of the corresponding integration, and some important properties for this kind of singular integral operator.

Riemann Boundary Value Problem of Non-Normal Type on the Infinite Straight Line  [PDF]
Lixia Cao
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.48165
Abstract:

Various kinds of Riemann boundary value problems (BVPs) for analytic functions on closed curves or on open arc, doubly periodic Riemann BVPs, doubly quasi-periodic Riemann BVPs, and BVPs for polyanalytic functions have been widely investigated in [1-8]. The main ap- proach is to use the decomposition of polyanalytic functions and their generalization to transform the boundary value problems to their corresponding boundary value problems for analytic functions. Recently, inverse Riemann BVPs for generalized analytic functions or bianalytic functions have been investigated in [9-12].
In this paper, we consider a kind of Riemann BVP of non-normal type on the infinite straight line and discuss the solvable conditions and the general solution for it.

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