Evaluation of Fracture Mechanisms in Al-Si Metal Matrix Nanocomposites Produced by Three Methods of Gravity Sand Casting,Squeeze Casting and Compo Casting in Semi-Solid State

Silicon - Magnetic stirring is considered to be the most useful stirring method in semi-solid casting processes which doesn’t have the restrictions of the mechanical stirring. In this...     

Alcohol-mediated haemolysis in yeast

Although yeast are generally non-haemolytic, we have found that addition of alcohol vapour confers haemolytic properties on many strains of yeast and other fungi. We have called this phenomenon 'microbial alcohol-conferred haemolysis' (MACH). MACH is species- and strain-specific: whereas all six Candida tropicalis strains tested were haemolytic in the presence of ethanol, none among 10 C. glabrata strains tested exhibited this phenomenon. Among 27 C. albicans strains and 11 Saccharomyces cerevisiae strains tested, ethanol-mediated haemolysis was observed in 11 and 4 strains, respectively. Haemolysis is also dependent on the alcohol moiety: n-butanol and n-pentanol could also confer haemolysis, whereas methanol and 2-propanol did not. Haemolysis was found to be dependent on initial oxidation of the alcohol. Reduced haemolysis was observed in specific alcohol dehydrogenase mutants of both Aspergillus nidulans and S. cerevisiae. MACH was not observed during anaerobic growth, and was reduced in the presence of pararosaniline, an aldehyde scavenger. Results suggest that initial oxidation of the alcohol to the corresponding aldehyde is an essential step in the observed phenomenon.     

Efficacy of synbiotic supplementation in patients with nonalcoholic fatty liver disease: A systematic review and meta-analysis of clinical trials: Synbiotic supplementation and NAFLD

ABSTRACT

Objective: We systematically reviewed available randomized clinical trials (RCTs) to elucidate the overall effects of synbiotic supplementation in patients with nonalcoholic fatty liver disease (NAFLD).

Methods: PubMed, Scopus, ISI Web of science and Google Scholar were searched up to December, 2017. All RCTs using synbiotic supplements to treat NAFLD included in this systematic review and meta-analysis. Mean Difference (MD) was pooled using a random-effects model.

Results: Eleven eligible databases from seven RCTs were identified for the present meta-analysis. Our results showed that synbiotic supplementation can decrease body weight, fasting blood sugar, insulin, low density lipoprotein cholesterol, total cholesterol, triglyceride, high-sensitivity C-reactive protein, tumor necrosis factor alpha, alanine transaminase and aspartate transaminase levels among patients with NAFLD. In contrast, synbiotic did not have favorable effects on body mass index (BMI), waist circumference, homeostasis model assessment for insulin resistance (HOMA-IR), and high density lipoprotein cholesterol (HDL) levels compared with the placebo group.

Conclusion: The current study revealed that synbiotic supplementation has favorable effect on inflammatory factors, liver enzymes and some anthropometric indices, lipid profiles and glucose homeostasis parameters in patients with NAFLD.     

Polypropylene cellulose‐based composites: The effect of bagasse reinforcement and polybutadiene isocyanate treatment on the mechanical properties

Using bagasse fiber as the reinforcing filler and polypropylene as the thermoplastic matrix polymer, a reinforced composite was prepared, and its mechanical properties examined as a function of the amount of compatibilizing agents used. In the sample preparation, four levels of fiber loading (10, 20, 30, and 40 wt %), three levels of polybutadiene isocyanate (PBNCO) content (0, 2, and 4 wt %) and two levels of maleated polypropylenes (MAPP) content (0 and 3 wt %) as compatibilizing agents were used. The tensile properties of the composites improved as the fiber loading and the compatibilizing agents increased, but the impact strength was significantly decreased. The mechanical study revealed that the positive effect of compatibilizing agents on interfacial bonding. The composites treated with PBNCO showed superior tensile and impact properties than those without treatment. The findings indicated that bagasse as agro‐waste material is a valuable renewable natural resource for composite production and could be utilized as a substitute for wood in composite industries. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Emulation of gas‐liquid flow in packed beds for offshore floating applications using a swell simulation hexapod

A laboratory‐scale packed column was positioned on a six degree of freedom swell simulation hexapod to emulate the hydrodynamics of packed bed scrubbers/reactors onboard offshore floating systems. The bed was instrumented with wire mesh capacitance sensors to measure liquid saturation and velocity fields, flow regime transition, liquid maldistribution, and tracer radial and axial dispersion patterns while robot was subject to sinusoidal translation (sway, heave) and rotation (roll, roll + pitch, yaw) motions at different frequencies. Three metrics were defined to analyze the deviations induced by the various column motions, namely, coefficient of variation and degree of uniformity for liquid saturation fluctuating fields, and effective Péclet number. Nontilting oscillations led to frequency‐independent maldistribution while tilting motions induced swirl/zigzag secondary circulation and prompted nonuniform maldistribution oscillations that deteriorated with decreasing frequencies. Regardless of excited degree of freedom, a qualitative loss of plug‐flow character was observed compared with static vertical beds which worsened as frequencies decreased. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2354–2367, 2015     

Starch,Sucrose, and Rezol® IL800 as Density Modifiers for Polyurethane Rigid Foams Formulated by Recycled Polyol

Waste polyurethane rigid foam (PUF) is recycled by the glycolysis process. The recycled product is used in a polyol blend, applied in a new foam formulation. Polyurethane rigid foams formulated by recycled polyols are highly dense compared to rigid foams formulated by virgin polyols. As these foams are mostly used in insulation, they make an extra mass to the main product or system that is insulated. Therefore, it is important to decrease their density as much as possible.

Some density modifiers such as starch, sucrose, and REZOL^® IL800 were investigated to recognize their effect on PUF's density.     

Numerical analysis for a vapor feed miniature direct methanol fuel cell system

A two-dimensional, multiphase model is presented and analyzed for a vapor feed DMFC system. The DMFC model is based on the multiphase mixture formulation and encompasses all components in the porous regions of a vapor feed DMFC using a single computation domain. The evaporation/condensation phenomenon in the anode flow channel is modeled in a separated way. An iterative numerical scheme is used to solve the governing equations in a coupled manner. Numerical simulations are carried out to explore the transient and polarization characteristics of the DMFC, including methanol crossover through the membrane, temperature evolution, anodic and cathodic overpotentials. The results indicate the anode flow channel for the feeding methanol solution is the key parameter for the DMFC performance. The numerical results are also compared with the experimental data with good agreement.     

不同螺栓布置下螺栓连接的滞回性能

从1994年北岭地震中可看到,栓焊节点的抗震性能较差。因此,常用于工业建筑和高层建筑中的抗弯框架多采用端板连接和T型螺栓连接。采用有限元方法,通过改变螺栓的纵横布置对比了14个试件的滞回性能。结果表明:假定两者总的耗能能力相同,则T型螺栓连接的抗弯能力和初始转动刚度均比基于AISC规范设计的端板螺栓连接高。在往复荷载作用下,螺栓布置的改变对T型螺栓连接破坏模式的影响要大于端板连接,端板连接更适用于具有初始几何缺陷的结构。     

弯曲受力时中空管以及混凝土填充纤维复合管的有限元模型:部分填充优化和杆设计方法

非线性有限元模型的拓展与验证在相关的论文(Son J,Fam A.中空管以及混凝土填充纤维复合管的有限元模型:第一部分——抗弯模型拓展与验证)中已被用于研究部分填充混凝土纤维增强复合材料线杆的抗弯性能。为提高抗弯强度和稳定性,建议采用部分填充厚壁管来降低造价。对不同直径与厚度比以及不同分层结构的悬臂单杆进行混凝土部分填充长度优化。研究发现,当下列任意一种情况出现时,优化长度会减少:当直径与厚度比变小时;当纤维角度相对于弯曲管纵向轴夹角增加时;当弯曲管中纵向纤维减少时;当采用侧向分布荷载代替端部集中荷载时。建立了计算中空管和混凝土填充FRP管承载力矩的简单表达式,基于同时发生在中空管和混凝土填充管处的破坏,结合简单的设计方法体系来优化混凝土填充管的长度。同时提出了计算锥形线杆的程序。