Effects of the killing rate on global bifurcation in an oncolytic-virus system with tumors

Oncologists and virologist are quite concerned about many kinds of issues related to tumor-virus dynamics in different virus models. Since the virus invasive behavior emerges from combined effects of tumor cell proliferation, migration and cell-microenvironment interactions, it has been recognized as a complex process and usually simulated by nonlinear differential systems. In this paper, a nonlinear differential model for tumor-virus dynamics is investigated mathematically. We first give a priori estimates for positive steady-states and analyze the stability of the positive constant solution. And then, based on these, we mainly discuss effects of the rate of killing infected cells on the bifurcation solution emanating from the positive constant solution by taking the killing rate as the bifurcation parameter.     

Interaction between trelagliptin and pepsin through spectroscopy methods and molecular dynamics simulation

The interaction between trelagliptin and pepsin was probed through spectroscopy methods and molecular dynamics simulation. Results of fluorescence lifetime and fluorescence spectroscopy analysis showed that trelagliptin can spontaneously interact with pepsin through a static quenching. This interaction was mainly driven by hydrogen bonding and van der Waals, as evident from thermodynamic parameters and molecular dynamics simulation. The microenvironment of tyrosine residues and the secondary structure of pepsin were slightly influenced by trelagliptin based on synchronous fluorescence, three-dimensional fluorescence, and circular dichroism spectra. In addition, the activity of pepsin was hardly affected by the insertion of trelagliptin. Molecular dynamics simulations were used to further analyze the pepsin–trelagliptin complex. This study provides useful information for binding mechanisms of trelagliptin on pepsin.     

双马煤矿废弃油井周围煤层H2S分布特征及其采掘影响范围划分

针对废弃油井周围煤层H2 S分布规律不清楚,采掘过程中影响范围不明确给煤矿安全开采造成严重威胁的难题,以煤油重叠区的双马煤矿为研究区,首先采用数值模拟方法研究了煤层内H2 S气体的渗流规律,然后结合数值模拟结果通过气体成分测试获得了H2 S气体的分布规律,最后根据采掘过程中H2 S气体的涌出规律对其影响范围进行了确定.结果表明:废弃油井周围H2 S气体浓度随距离废弃油井增加呈递减分布,废弃油井内气体压力越高,H2 S气体渗透范围越大;工作面过废弃油井过程中H2 S气体浓度呈现出较高—降低—平稳—降低—急剧下降的变化规律;双马煤矿废弃油井影响区煤层H2 S气体的渗透半径为500 m,采掘影响范围为700 m.研究结果为工作面H2 S气体的治理提供指导.     

Acetate chitosan with CaCO3 doping form tough hydrogel for hemostasis and wound healing

In recent years, chitosan has been applied for wound management due to its properties of biocompatibility, biodegradability, antimicrobial activity, and low immunogenicity. But the poor water solubility in neutral pH limited its further application in clinical wound healing. To overcome this problem, acetate chitosan was developed and approved as commercial products for wound healing. However, the acidity of acetate chitosan was potentially allergenic, and the poor mechanical properties of its formed hydrogels also hindered the therapeutic efficacy in wound care. In this study, CaCO₃ was simply doped into acetate chitosan to form the wound dressing. After absorbing water, the H⁺ of acetate chitosan reacted with CaCO₃ to release Ca²⁺, resulting in acidity decreased. The production of Ca²⁺ and residue of CaCO₃ cross‐linked with chitosan to form a tough hydrogel by electrostatic interaction. The physical characteristics, swelling, mechanical testing, and blood clotting were evaluated. The results in vitro demonstrated that after doping CaCO₃ into acetate chitosan, the mechanical properties and blood clotting of the formed hydrogel were increased. Then, the evaluation of hydrogels in vivo revealed that it can also accelerate the wound healing by promoting re‐epithelization and collagen deposition. This simple way by doping CaCO₃ into acetate chitosan can increase wound healing, and it can also broad the application of acetate chitosan in clinical use.     

Facile preparation of ZrCO composite aerogel with high specific surface area and low thermal conductivity

A novel ZrCO composite aerogel is synthesized using zirconium oxychloride and resorcinol–formaldehyde (RF) as precursors through the sol–gel route and carbothermal reduction process. The effects of different Zr/R molar ratios and calcination temperatures on the physical chemistry properties of ZrCO aerogels are investigated. The ZrCO composite aerogel consists of the C/ZrO₂/ZrC ternary aerogel. The results show that with the increase of R/Zr molar ratios, the specific surface area and bulk density increase with calcination temperature up to 1300?°C, but decrease at even temperature (1500?°C). The specific surface area is as high as 637.4?m²/g for ZrCO composite aerogel (R:Zr?=?2:1), which was higher than ever reported. As the heat-treatment temperature increases to 1500?°C, the ZrC crystalline phase occurs and the t-ZrO₂ phase still appears within the composite. The thermal conductivity of the carbon fiber mat-reinforced composite aerogel is as low as 0.057?W/m/K at room temperature (25?°C).

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Isolation and structure determination of a new flavone glycoside from seed residues of seabuckthorn (Hippophae rhamnoides L.)

In this study, a valid method was established for the isolation and purification of flavone glycosides from Hippophae rhamnoides L. seed residues using high-speed counter-current chromatography in one step, with a solvent system of ethyl acetate-methanol-n-butyl alcohol-water (9:1:0.5:9, v/v/v/v). A total of 28.8 mg compound I and 57.3 mg compound II were obtained from 200 mg of flavone H-glycosides rich extract, with purities of 98.3 and 96.4%, respectively. The structures of two compounds were identified by MS and NMR. 3-O-β-D-Sophorosylkaempferol-7-O-{3-O-[2(E)-2,6-dimethyl-6-hydroxyocta-2,7-dienoyl]}-α-L-rhamnoside is compound I and compound II named hippophanone is a new compound were identified by MS and NMR. The method was efficient and convenient, which could be used for the preparative separation of flavone glycosides from H. rhamnoides L. seed residues.     

Ky Fan不等式组解的通有稳定性

本文证明在不动点理论、鞍点理论及多目标优化理论中均有重要应用的Ｋｙ Ｆａｎ不等式组的解集是通有稳定的。