Liquid-liquid-vapor phase equilibria behavior of certain binary carbon dioxide + n-alkylbenzene mixtures

The liquid-liquid-vapor loci for the binary mixtures CO₂ + n-hexylbenzene, n-heptylbenzene, and n-octylbenzene were experimentally studied. The compositions and molar volumes of the liquid phases are reported along with the pressure and temperature. For these three alkylbenzenes, the nature of the liquid-liquid-vapor loci experiences a transition, with the CO₂ + n-heptylbenzene mixture exhibiting two separate liquid-liquid-vapor branches.     

A combination therapy strategy for treating antibiotic resistant biofilm infection using a guanidinium derivative and nanoparticulate Ag(0) derived hybrid gel conjugate

Bacteria organized in biofilms show significant tolerance to conventional antibiotics compared to their planktonic counterparts and form the basis for chronic infections. Biofilms are composites of different types of extracellular polymeric substances that help in resisting several host-defense measures, including phagocytosis. These are increasingly being recognized as a passive virulence factor that enables many infectious diseases to proliferate and an essential contributing facet to anti-microbial resistance. Thus, inhibition and dispersion of biofilms are linked to addressing the issues associated with therapeutic challenges imposed by biofilms. This report is to address this complex issue using a self-assembled guanidinium–Ag(0) nanoparticle (AD-L@Ag(0)) hybrid gel composite for executing a combination therapy strategy for six difficult to treat biofilm-forming and multidrug-resistant bacteria. Improved efficacy was achieved primarily through effective biofilm inhibition and dispersion by the cationic guanidinium ion derivative, while Ag(0) contributes to the subsequent bactericidal activity on planktonic bacteria. Minimum Inhibitory Concentration (MIC) of the AD-L@Ag(0) formulation was tested against Acinetobacter baumannii (25 μg mL⁻¹), Pseudomonas aeruginosa (0.78 μg mL⁻¹), Staphylococcus aureus (0.19 μg mL⁻¹), Klebsiella pneumoniae (0.78 μg mL⁻¹), Escherichia coli (clinical isolate (6.25 μg mL⁻¹)), Klebsiella pneumoniae (clinical isolate (50 μg mL⁻¹)), Shigella flexneri (clinical isolate (0.39 μg mL⁻¹)) and Streptococcus pneumoniae (6.25 μg mL⁻¹). Minimum bactericidal concentration, and MBIC₅₀ and MBIC₉₀ (Minimum Biofilm Inhibitory Concentration at 50% and 90% reduction, respectively) were evaluated for these pathogens. All these results confirmed the efficacy of the formulation AD-L@Ag(0). Minimum Biofilm Eradication Concentration (MBEC) for the respective pathogens was examined by following the exopolysaccharide quantification method to establish its potency in inhibition of biofilm formation, as well as eradication of mature biofilms. These effects were attributed to the bactericidal effect of AD-L@Ag(0) on biofilm mass-associated bacteria. The observed efficacy of this non-cytotoxic therapeutic combination (AD-L@Ag(0)) was found to be better than that reported in the existing literature for treating extremely drug-resistant bacterial strains, as well as for reducing the bacterial infection load at a surgical site in a small animal BALB/c model. Thus, AD-L@Ag(0) could be a promising candidate for anti-microbial coatings on surgical instruments, wound dressing, tissue engineering, and medical implants.

Dispersion of biofilms that protect bacteria and its subsequent killing in the planktonic state are effectively achieved by a guanidinium–Ag(0) nanocomposite.     

Design,synthesis and biological activity against estrogen receptor-dependent breast cancer of furo[1]benzofuran derivatives

The docking study on a series of furo[1]benzofuran derivatives with ERα has been demonstrated. The synthesis and characterization of a series of furo[1]benzofuran derivatives were described. All the target compounds were conducted to in vitro for the inhibitory activities against human breast cancer strains T-47D, MCF-7 and toxicity against human liver normal cell strains HL7702 via MTT assay. Most of the target compounds possessed anti-estrogen receptor-dependent breast cancer activities with weak toxicity to healthy cell strains. The preliminary structure–activity relationships were discussed.     

平面不可压缩Navier-Stokes方程五模系统的力学机理及能量演化

该文研究了平面不可压缩Navier-Stokes方程五模系统的力学机理及能量演化问题,通过将五模混沌系统转换成Kolmogorov形系统,把系统的力矩分为三种类型:惯性力矩,耗散力矩和外力矩.通过不同力矩的结合分析和研究了系统产生混沌的关键因素和物理意义.讨论了能量与雷诺数之间的关系.研究表明三种力矩的耦合是产生混沌的必要条件,而且只有耗散力矩和驱动力矩(外力矩)相匹配时,系统才能产生混沌,其中任何两种力矩耦合均不可能产生混沌.外力矩给系统提供能量,导致系统失稳出现分岔与混沌.引进Casimir函数分析系统的动力学行为和能量演化,并估计混沌吸引子的界.Casimir函数反映了能量转换和轨道与平衡点间的距离.     

爆炸载荷作用下焊缝区附近埋地X70钢管的动力响应分析

爆破地震效应对埋地管线的影响已成为工程爆破领域研究的热点。基于有限元软件ANSYS/LS-DYNA,以两种含Y型焊缝(坡口有2 mm余高焊缝和坡口无余高焊缝)的埋地X70钢管为例,数值模拟研究了TNT炸药量相同(4.473 kg)而炸高(60.0、85.0和110.0 cm)不同时,焊缝区附近埋地X70钢管的动力响应规律。研究表明:当炸高为60.0 cm时,焊缝有余高的管道受应力集中的影响较大,且先于焊缝无余高的管道进入屈服阶段;当炸高为60.0和85.0 cm时,焊缝有余高的管道整体抵抗变形的能力明显弱于焊缝无余高的管道。管土间的相互作用对X70管道背爆面有支撑作用,可有效地减小管道背爆面的位移。在相同条件下,焊缝有余高的X70管道抵抗振动的性能弱于焊缝无余高的管道,且与焊缝形式相比,炸高对含焊缝区的X70管道的最大振速起主要影响作用。     

Cross metathesis of butene-2 and ethene to propene over Mo/MCM-22-Al2O3 catalysts with different Al2O3 contents

A series of 3.0Mo/MCM-22-Al2O3 catalysts with γ-Al2O3 contents in the range of 0-100 wt% were prepared and applied in the metathesis reaction of ethene and butene-2. Addition of γ-Al2O3 did not affect the structure of MCM-22 zeolite as evidenced by XRD and N2 adsorption measurements. It was deduced from TPR experiments that γ-Al2O3 phase favored the formation of polymolybdate or multilayered Mo oxide, while more Al2(MoO4)3 species were generated over MCM-22 zeolites. Alumina content in the support was directly related to the metathesis activity of ethene and butene-2 to propene. Mo species with higher valence (Mo⁶⁺or Mo⁵⁺) contributed more to the excellent performance of catalyst than metallic Mo. The best catalyst activity and stability was obtained over 3.0Mo/(MCM-22-30%Al2O3) under the reaction condition of 1.0 MPa and 125 ℃ using N2 as the pretreatment gas.     

3D nonlinear variable strain-rate-dependent-order fractional thermoviscoelastic dynamic stress investigation and vibration of thick transversely graded rotating annular plates/discs

In the present article, the idea of using the variable-order fractional-derivative thermoviscoelastic constitutive laws in dynamic stress and vibration analysis of the engineering structures, the required implementation backgrounds, and the relevant numerical solution procedures are investigated for the first time. In this regard, dynamic 3D stress and displacement fields and radial/transverse vibrations of transversely graded viscoelastic spinning thick plates/discs exposed to sudden thermoelastic loads are investigated. Instead of using the approximate plate theories, the exact thermoviscoelasticity theory is employed in the development of the governing equations. Since the variable fractional order is dependent on the localized deformation rates, the resulting thermoviscoelastic integro-differential equations are nonlinear. These equations are solved by utilizing a combination of the second-order backward/central/forward finite difference discretization of the spatial and time domains, numerical evaluation and updating of the Caputo-type fractional derivatives, updating the growing number of terms of the governing equations, and Picard's iterations. Various edge conditions are considered. Finally, comprehensive sensitivity analyses and various 3D plots are presented and discussed regarding the effects of the variable fractional order of the constitutive law, time variations of the nonuniformly distributed transverse loads, and edge conditions on the distributions and damping of the resulting displacement and stress components.     

荷移分光光度法测定甲氧氯普胺

采用分光光度法研究了甲氧氯普胺与茜素红之间的荷移反应。确定了反应条件,建立了一种快速简便测定甲氧氯普胺的荷移分光光度法。实验表明,甲氧氯普胺与茜素红在乙醇—水介质中,室温条件下即可形成稳定的1：2型荷移络合物,该络合物的λmax=528nm,表观摩尔吸光系数为4.66×10^3L·mol^-1·cm^-1。甲氧氯普胺药物质量浓度在10-70mg/L范围内服从比耳定律,相关系数为0.9991。测定结果的相对标准偏差为1.08%（n=6）,回收率为98.2%—101.6%。     

Comparative study on interactions between laser and arc plasma during laser-GTA welding and laser-GMA welding

This paper describes an investigation on differences in interactions between laser and arc plasma during laser-gas tungsten arc (LT) welding and laser-gas metal arc (LM) welding. The characteristics of LT heat source and LM heat source, such as plasma behavior, heat penetration ability and spectral information were comparably studied. Based on the plasma discharge theory, the interactions during plasma discharge were modeled and analyzed. Results show that in both LT and LM welding, coupling discharge between the laser keyhole plasma and arc happens, which strongly enhance the arc. But, the enhancing effect in LT welding is much more sensitive than that in LM welding when parameters are adjusted.