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Chen X.,Northwest University, China | Li Y.,Northwest University, China | Zhang Y.,Northwest University, China | Yang J.,Northwest University, China | And 2 more authors.
Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences | Year: 2017

TEM-1 beta-lactamases can accurately catalyze the hydrolysis of the beta-lactam rings in beta-lactam antibiotics, which make beta-lactam antibiotics lose its activity, and the prerequisite for the hydrolysis procedure in the binding interaction of TEM-1 beta-lactamases with beta-lactam antibiotics is the beta-lactam rings in beta-lactam antibiotics. Therefore, the binding of TEM-1 beta-lactamase to three beta-lactam antibiotics including penicillin G, cefalexin as well as cefoxitin was explored here by frontal affinity chromatography in combination with fluorescence spectra, adsorption and thermodynamic data in the temperature range of 278–288 K under simulated physiological conditions. The results showed that all the binding of TEM-1 beta-lactamase to the three antibiotics were spontaneously exothermic processes with the binding constants of 8.718 × 103, 6.624 × 103 and 2.244 × 103 (mol/L), respectively at 288 K. All the TEM-1 beta-lactamases were immobilized on the surface of the stationary phase in the mode of monolayer and there existed only one type of binding sites on them. Each TEM-1 beta-lactamase bound with only one beta-lactam antibiotic and hydrogen bond interaction and Van der Waals force were the main forces between them. This work provided an insight into the binding interactions between TEM-1 beta-lactamases and beta-lactam antibiotics, which may be beneficial for the designing and developing of new substrates resistant to TEM-1 beta-lactamases. © 2017 Elsevier B.V.


Wang F.S.,Northwestern Polytechnical University | Ding N.,Industry Weapon | Liu Z.Q.,Northwestern Polytechnical University | Ji Y.Y.,Northwestern Polytechnical University | Yue Z.F.,Northwestern Polytechnical University
Composite Structures | Year: 2014

Ablation damage characteristic of carbon fiber/epoxy composite laminate suffered from lightning strike was studied by the coupled thermal-electrical-structural analysis and element deletion. Residual strength of composite laminate after lightning strike ablation was globally predicted by Hashin criterion. Results show that lightning ablation effects decrease with the increasing electrical conductivity or specific heat, while thermal conductivity has little influence on them. Residual strength of composite laminate is generally greater than 80% and decreases with the increasing peak current or ratio of time to the maximum current and that to 50% of the maximum current under static tensile load. The work can provide detailed technical support for lightning damage evaluation and residual strength prediction of aircraft carbon fiber/epoxy composite laminates in theory, which is seldom reported compared with lightning test researches available up to now. © 2014 Elsevier Ltd.


Tian X.,Shandong Polytechnic University | Li C.X.,Industry Weapon
Applied Mechanics and Materials | Year: 2013

Consider the rod on elastic foundation. Its discrete model is the simply connected spring-mass system with partial mass connected to the ground. The inverse mode problem of constructing the physical elements of the system from two eigenpairs, the spring stiffness of the system is considered. The necessary and sufficient conditions for constructing a physical realizable system with positive mass and stiffness elements are established. If these conditions are satisfied, the rod on the elastic foundation may be constructed uniquely. The numerical methods and examples are given finally. © (2013) Trans Tech Publications, Switzerland.


Tian X.,Shandong Polytechnic University | Li C.X.,Industry Weapon
Applied Mechanics and Materials | Year: 2013

Consider the simply connected spring-mass system with partial mass connected to the ground. The inverse mode problem of constructing the physical elements of the system from two eigenpairs, the grounding spring stiffness and total mass of the system is considered. The necessary and sufficient conditions for constructing a physical realizable system with positive mass and stiffness elements are established. If these conditions are satisfied, the grounding spring-mass system may be constructed uniquely. The numerical methods and examples are given finally. © (2013) Trans Tech Publications, Switzerland.


Tian X.,University of Science and Technology of China | Li C.-X.,Industry Weapon
Progress in Civil, Architectural and Hydraulic Engineering - Selected Papers of the 4th International Conference on Civil, Architectural and Hydraulic Engineering, ICCAHE 2015 | Year: 2016

The effects of adding spring to a beam on its frequencies are investigated for cantilever beam. Consider two systems: cantilever beam and the same cantilever beam added additional spring. By using two natural frequencies of each system, we identify the structural parameter of the original system. The method is nondestructive. The stiffness of the additional springs is known. Given the natural frequencies of each system, the stiffness of the additional springs and the total mass of the beam, the bending rigidity and density of cantilever beam are reconstructed. The solution of the problem is given and the conditions for the construction of the beam are derived. It is not iterative and therefore demands a modest computational effort. © 2016 Taylor & Francis Group, London.


Li R.-F.,Hubei Zhongshan Hospital | Li R.-F.,University of Chicago | Feng Y.-Q.,Industry Weapon | Chen J.-H.,Hubei Zhongshan Hospital | And 3 more authors.
Experimental and Therapeutic Medicine | Year: 2015

Treatments for leukemia remain unsatisfactory. Conventional chemotherapy agents that aim to kill tumor cells may also damage normal cells and thus result in severe side‑effects. Naringenin, a natural polyphenolic compound with antioxidant effects, has been revealed to have significant antitumor effects with low toxicity in preliminary studies. Thus, it is considered as one of the most promising flavonoids in the treatment of leukemia. In the present study, the effects of naringenin on the K562 human leukemia cell line and the underlying mechanisms were explored in vitro. In addition, human peripheral blood polymorphonuclear leukocytes (PMNs) were used as a normal control in order to evaluate the effects of naringenin on normal granulocytes and in the mediation of Adriamycin (ADM)‑induced oxidative damage. The results revealed that K562 proliferation was significantly inhibited by naringenin in a time‑ and concentration‑dependent manner; however, minimal cytotoxic effects were observed in PMNs when naringenin was used at concentrations <400 μmol/l. Morphological changes indicative of apoptosis were observed in naringenin‑treated K562 cells. Flow cytometric analysis indicated that the K562 cells were arrested in the G0/G1 phase of the cell cycle with a significantly upregulated rate of apoptosis. Furthermore, in the naringenin‑treated K562 cells, the labeling index of proliferating cell nuclear antigen was observed to be increased by immunochemical staining, the mRNA and protein expression levels of p21/WAF1 were strongly upregulated in reverse transcription‑polymerase chain reaction and western blot analyses, whereas p53 gene expression was not significantly changed. In PMNs to which naringenin (50~80 μmol/l) was added 1 h subsequent to ADM, the cell damage induced by ADM was significantly reduced, coincident with reductions in the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) and increases in the activity of superoxide dismutase and glutathione peroxidase. However, the cytotoxic effect of ADM in K562 cells was not significantly altered by naringenin, and the oxidative stress indices in K562 cells remained stable. In conclusion, the present study revealed the promising value of naringenin in leukemia treatment. Naringenin demonstrated a significant inhibitory effect on the growth of K562 cells but not on normal PMNs. Furthermore, naringenin protected PMNs from ADM‑induced oxidative damage at low concentrations. Cell cycle arrest and apoptosis‑inducing effects, achieved through p53‑independent p21/WAF1 upregulation, are likely to be the mechanism of the antileukemic effects of naringenin, and the protective effect against ADM chemotherapy‑induced damage in PMNs may be due to the antioxidant capability of this agent at low concentrations. © 2015, Spandidos Publications. All rights reserved.


Tian X.,Shandong Polytechnic University | Li C.X.,Industry Weapon
Applied Mechanics and Materials | Year: 2012

The mass-normalized stiffness matrix of the star spring-mass system is an arrowhead matrix. Given two eigenpairs of the arrowhead matrix. It is assumed that the total mass of a star spring-mass system is known. The problem of constructing the physical elements of the system from the known data is considered. The necessary and sufficient conditions for the construction of a physical realizable system with positive mass and spring stiffness are established. If these conditions are satisfied, the system may be constructed uniquely. © (2012) Trans Tech Publications.


Tian X.,Shandong Polytechnic University | Li C.X.,Industry Weapon
Applied Mechanics and Materials | Year: 2012

Given the odd/even degree eigenpair and the even degree eigenpair of a simply connected central symmetric spring-mass system respectively. The inverse mode problem of constructing the physical elements of the system from two eigenpairs and the total mass of the system is considered. The necessary and sufficient conditions for constructing of a physical realizable system with positive mass and stiffness elements are established. If these conditions are satisfied, the simply connected central symmetric spring-mass system may be constructed uniquely. The numerical methods and examples are given finally. © (2012) Trans Tech Publications.


PubMed | Industry Weapon, Hubei Zhongshan Hospital, University of Chicago and Hubei University
Type: Journal Article | Journal: Experimental and therapeutic medicine | Year: 2015

Treatments for leukemia remain unsatisfactory. Conventional chemotherapy agents that aim to kill tumor cells may also damage normal cells and thus result in severe side-effects. Naringenin, a natural polyphenolic compound with antioxidant effects, has been revealed to have significant antitumor effects with low toxicity in preliminary studies. Thus, it is considered as one of the most promising flavonoids in the treatment of leukemia. In the present study, the effects of naringenin on the K562 human leukemia cell line and the underlying mechanisms were explored


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