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Liu, Yuji,Xia, Jianye The Korean Society for Computational and Applied M 2010 Journal of applied mathematics & informatics Vol.28 No.1
This paper is concerned with the neutral impulsive functional differential equations $$\{{x'(t)\;+\;a(t)x(t)\;=\;f(t,\;x(t\;-\;\tau(t),\;x'(t\;-\;\delta(t))),\;a.e.\;t\;{\in}\;R, \atop {\Delta}x(t_k)\;=\;b_kx(t_k),\;k\;{\in}\;Z.$$ Sufficient conditions for the existence of at least three positive T-periodic solution are established. Our results generalize and improve the known ones. Some examples are presented to illustrate the main results.
Positive periodic solutions of impulsive functional differential equations
Yuji Liu,Jianye Xia,Weigao Ge 한국전산응용수학회 2005 Journal of applied mathematics & informatics Vol.19 No.1-2
We study the existence and nonexistence of positive periodic solutions of a non-autonomous functional differential equation with impulses. The equations we study may be of delay, advance or mixed type functional differential equations and the impulses may cause the existence of positive periodic solutions. The methods employed are fixed-point index theorem, Leray-Schauder degree, and upper and lower solutions. The results obtained are new, and some examples are given to illustrate our main results.
Yuji Liu,Jianye Xia 한국전산응용수학회 2010 Journal of applied mathematics & informatics Vol.28 No.1
This paper is concerned with the neutral impulsive functional differential equations [수식]Sufficient conditions for the existence of at least three positive T−periodic solution are established. Our results generalize and improve the known ones. Some examples are presented to illustrate the main results.
POSITIVE PERIODIC SOLUTIONS OF IMPULSIVE FUNCTIONAL DIFFERENTIAL EQUATIONS
LIU, YUJI,XIA, JIANYE,GE, WEIGAO 한국전산응용수학회 2005 Journal of applied mathematics & informatics Vol.19 No.1
We study the existence and nonexistence of positive periodic solutions of a non-autonomous functional differential equation with impulses. The equations we study may be of delay, advance or mixed type functional differential equations and the impulses may cause the existence of positive periodic solutions. The methods employed are fixed-point index theorem, Leray-Schauder degree, and upper and lower solutions. The results obtained are new, and some examples are given to illustrate our main results.
Ao Pan,Minghui Xie,Jianye Xia,Ju Chu,Ying-ping Zhuang 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.1
The influence of impeller structure on the mass transfer characteristics was studied with the steady-state method for gas-liquid volumetric mass transfer coefficient (kLa). The single-impeller configurations included eight impeller types (three radial flow impellers, four axial flow impellers and one mixed flow impeller), and the doubleimpeller included three configurations (RT+RT, RT+WHD, WHD+WHD). For single-impeller, the gas-liquid mass transfer rates of radial flow impellers were better than those of axial flow impellers under the same rotation speed and gas flow rate. The mass transfer performance (defined as the volumetric mass transfer coefficient per unit power input) of radial flow impellers were also better than that of axial flow impellers. With the same kLa value under a certain gas flow rate, the local bubble size distribution between radial flow impeller and axial flow impeller was similar. As for double impellers, RT+RT provided the highest mass transfer rate under certain rotation speed and gas flow rate, while WHD+WHD gave the highest values of gas-liquid mass transfer coefficient with the same power consumption.
Junming Tang,Jianing Wang,Linyun Guo,Xia Kong,Jianye Yang,Fei Zheng,Lei Zhang,Yongzhang Huang 한국분자세포생물학회 2010 Molecules and cells Vol.29 No.1
Mesenchymal stem cells (MSCs) are a promising source for cell-based treatment of myocardial infarction (MI), but existing strategies are restricted by low cell survival and engraftment. We examined whether SDF-1 transfection improve MSC viability and paracrine action in infarcted hearts. We found SDF-1-modified MSCs effectively ex-pressed SDF-1 for at least 21days after exposure to hy-poxia. The apoptosis of Ad-SDF-1-MSCs was 42% of that seen in Ad-EGFP-MSCs and 53% of untreated MSCs. In the infarcted hearts, the number of DAPI-labeling cells in the Ad-SDF-1-MSC group was 5-fold that in the Ad-EGFP-MSC group. Importantly, expression of antifibrotic factor, HGF, was detected in cultured MSCs, and HGF expression lev-els were higher in Ad-SDF-MSC-treated hearts, compared with Ad-EGFP-MSC or control hearts. Compared with the control group, Ad-SDF-MSC transplantation significantly decreased the expression of collagens I and III and matrix metalloproteinase 2 and 9, but heart function was im-proved in d-SDF-MSC-treated animals. In conclusion, SDF-1–modified MSCs enhanced the tolerance of engrafted MSCs to hypoxic injury in vitro and improved their viability in infarcted hearts, thus helping preserve the contractile function and attenuate left ventricle (LV) remodeling, and this may be at least partly mediated by enhanced paracrine signaling from MSCs via antifibrotic factors such as HGF.
Tang, Junming,Wang, Jianing,Guo, Linyun,Kong, Xia,Yang, Jianye,Zheng, Fei,Zhang, Lei,Huang, Yongzhang Korean Society for Molecular and Cellular Biology 2010 Molecules and cells Vol.29 No.1
Mesenchymal stem cells (MSCs) are a promising source for cell-based treatment of myocardial infarction (MI), but existing strategies are restricted by low cell survival and engraftment. We examined whether SDF-1 transfection improve MSC viability and paracrine action in infarcted hearts. We found SDF-1-modified MSCs effectively expressed SDF-1 for at least 21days after exposure to hypoxia. The apoptosis of Ad-SDF-1-MSCs was 42% of that seen in Ad-EGFP-MSCs and 53% of untreated MSCs. In the infarcted hearts, the number of DAPI-labeling cells in the Ad-SDF-1-MSC group was 5-fold that in the Ad-EGFP-MSC group. Importantly, expression of antifibrotic factor, HGF, was detected in cultured MSCs, and HGF expression levels were higher in Ad-SDF-MSC-treated hearts, compared with Ad-EGFP-MSC or control hearts. Compared with the control group, Ad-SDF-MSC transplantation significantly decreased the expression of collagens I and III and matrix metalloproteinase 2 and 9, but heart function was improved in d-SDF-MSC-treated animals. In conclusion, SDF-1-modified MSCs enhanced the tolerance of engrafted MSCs to hypoxic injury in vitro and improved their viability in infarcted hearts, thus helping preserve the contractile function and attenuate left ventricle (LV) remodeling, and this may be at least partly mediated by enhanced paracrine signaling from MSCs via antifibrotic factors such as HGF.
Haifeng Hang,Yuanxin Guo,Jian Liu,Li Bai,Jianye Xia,Meijin Guo,Matthew Hui 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.3
We previously developed an inverted frustoconical shaking bioreactor (IFSB) which had high mammalian cell culture performance when compared with a mechanically stirred tank reactor (STR) or a flat-bottom shaking bioreactor (FBSB). Here, we determined the mixing time (t) and volumetric oxygen transfer coefficient (kLa) of this IFSB at various speeds, and simulated the fluid hydrodynamics, including the shear stress and specific surface area, by computational fluid dynamics. The shortest mixing time was observed in a STR. The maximum kLa value of 12/h was achieved in the IFSB at an aeration rate of 4 L/h, demonstrating that our IFSB has enhanced oxygen transfer capabilities needed to meet the demands of mammalian cells. Simulation studies revealed a 3% greater specific surface area and a 21% lower shear strain in the IFSB compared to an FBSB under the same conditions. Additionally, the conical angle of the vessel, which significantly affected cell growth and recombinant protein production,was tested here. We conclude that, compared to the STR and FBSB, the IFSB has an increased liquid surface area for oxygen uptake and exhaust CO_2 stripping,an enhanced k_La for cell robust growth to a high cell density, and a lower shear stress to alleviate cell damage.
Wang, Tao,Shi, Feng,Jin, Yan,Yap, Pew-Thian,Wee, Chong-Yaw,Zhang, Jianye,Yang, Cece,Li, Xia,Xiao, Shifu,Shen, Dinggang Hindawi Publishing Corporation 2016 Neural plasticity Vol.2016 No.-
<P>Alzheimer's disease (AD) is the most common form of dementia in elderly people. It is an irreversible and progressive brain disease. In this paper, we utilized diffusion-weighted imaging (DWI) to detect abnormal topological organization of white matter (WM) structural networks. We compared the differences between WM connectivity characteristics at global, regional, and local levels in 26 patients with probable AD and 16 normal control (NC) elderly subjects, using connectivity networks constructed with the diffusion tensor imaging (DTI) model and the high angular resolution diffusion imaging (HARDI) model, respectively. At the global level, we found that the WM structural networks of both AD and NC groups had a small-world topology; however, the AD group showed a significant decrease in both global and local efficiency, but an increase in clustering coefficient and the average shortest path length. We further found that the AD patients had significantly decreased nodal efficiency at the regional level, as well as weaker connections in multiple local cortical and subcortical regions, such as precuneus, temporal lobe, hippocampus, and thalamus. The HARDI model was found to be more advantageous than the DTI model, as it was more sensitive to the deficiencies in AD at all of the three levels.</P>