Compressive properties of a new metal–polymer hybrid material

Compressive properties of a new hybrid material, fabricated through filling of an aluminum foam with a thermoplastic polymer, are investigated. Static (0.01 s⁻¹) and dynamic (100 s⁻¹) compression testing has been carried out to study the behavior of the hybrid material in comparison with its parent foam and polymer materials. Considering the behavior of metal foams, the point on a compressive stress–strain curve corresponding to the minimum cushion factor is defined as the “densification” point. The analysis of the stress–strain curves provides insight into the load carrying and energy absorption characteristics of the hybrid material. At both strain rates, the hybrid is found to carry higher stresses and absorb more energy at “densification” than the foam or polymer.     

Development,characterization, and modeling of environmentally friendly open‐cell acoustic foams

This study shows the development of new polymeric open‐cell foams from polypropylene (PP) and polylactide (PLA) resins with a focus on sound absorption properties and modeling of these foams. The objective is to develop new environmentally friendly foams to replace the existing non‐recyclable Polyurethane foams are currently used for sound insulation in industry. Through this research, open‐cell foams of about 90% porosity were fabricated from PP and PLA. These resins were selected since PP is a recyclable thermoplastic polymer, and PLA is a bio‐based thermoplastic polymer made from renewable resources. Polyurethane (PU) foam which is currently used for sound absorption and noise control in industry was compared to the fabricated PP and PLA foams. As the first attempt to fabricate environmentally friendly acoustic foams, the resulting foam structures show improved properties as compared to the existing materials. The average absorption of PP and PLA foams fabricated is in the range of 0.42–0.55 which is comparable or even higher than the average absorption of PU foam. To better understand the effect of structural and material properties on sound absorption and further improve the acoustic performance of bio‐based foams, an analytical model based on Johnson–Champoux–Allard model was used to numerically simulate the acoustic performance of foams under study. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers     

Evaluating and empirical modeling of the electrocatalytic activity and morphology of electrospun polyacrylonitrile/polyaniline/tungsten trioxide nanofibers

Abstract

Electrically conductive polyacrylonitrile/polyaniline/tungsten oxide (PAN/PANI/WO₃) nanofibers were produced through an electrospinning method. The PAN polymer was used to enhance the spinnability of the polyaniline solution. The surface morphology and electrocatalytic properties of the mats were examined by scanning electron microscopy and electrochemical impedance spectroscopy method. Response surface methodology was applied to predict the relation between both the average diameters of the nanofibers and the charge-transfer resistance (R_ct) of nanofibrous mats with the concentration of polyaniline and tungsten oxide. Design-Expert7 software was selected for the response data analysis of the contour plots. Direct relation was observed between the average diameters of the nanofibers with WO₃ concentration in electrospinning solution. However, with increasing polyaniline content, the average diameters of nanofibers decreased. The results showed that both the PANI and WO₃ concentrations (%wt.) had significant effects on the nanofibers diameters. In the case of electrocatalytic activity, the increasing of both composite components in the spinning solutions had positive effect on the lowering of the charge-transfer resistance and the changes were statistically significant.     

Microstructured Biodegradable Fibers for Advanced Control Delivery

Biodegradable polymers are increasingly employed at the heart of therapeutic devices. Particularly in the form of thin and elongated fibers, they offer an effective strategy for controlled release in a variety of biomedical configurations such as sutures, scaffolds, wound dressings, surgical or imaging probes, and smart textiles. So far however, the fabrication of fiber‐based drug delivery systems has been unable to fulfill significant requirements of medicated fibers such as multifunctionality, adequate mechanical strength, drug loading capability, and complex release profiles of multiple substances. Here, a novel paradigm in the design and fabrication of microstructured biodegradable fibers with tailored mechanical properties and capable of predefined release patterns from multiple reservoirs is proposed. Different biodegradable polymers compatible with the scalable thermal drawing process are identified, and their release properties as thin films of various thicknesses in the fiber form are experimentally investigated and modeled. Multimaterial microstructured fibers with predictable complex release profiles of potentially different substances are then designed and fabricated. Moreover, the tunability of the mechanical properties via tailoring the drawing process parameters is demonstrated, as well as the ability to weave such fibers. This work establishes a novel platform for biodegradable microstructured fibers for applications in implants, sutures, wound dressing, or tissue scaffolds.     

Cu/Oil nanofluids flow over a semi‐infinite plate accounting an experimental model

In this study, the flow of Cu/oil nanofluids over an impermeable semi‐infinite plate was investigated. A complete single‐phase modeling of nanofluids flowing over a semi‐infinite plate was performed, bringing into account, real experimental data of oil‐based nanofluids. The empirical correlations revealed that the viscosity and thermal conductivity of the pure oil and oil‐based nanofluids strongly depend on temperature. The similarity transformation method was utilized to transform governing partial differential equations into coupled nonlinear ordinary differential equations solved by employing the standard Runge–Kutta. The results showed that even low volumetric fraction of copper/oil nanofluids noticeably enhanced the heat transfer; however, such behavior was not predicted accounting the classic modeling of nanofluids. Furthermore, both hydrodynamics and thermal characteristics were reliant on the thermal boundary conditions, which this seems to have received a marginal focus in the existing literature.     

Thermodynamic and Electrochemical Investigations of Poly(Methyl Methacrylate–Maleic Anhydride) as Corrosion Inhibitors for Mild Steel in 0.5 M HCl

Protection of Metals and Physical Chemistry of Surfaces - In this research, poly(methyl methacrylate-maleic anhydride)P(MMA-MAH)s with different percentages methyl methacrylate and maleic anhydride...     

Synthesis of a new magnetic adsorbent using green tea leaf extract and its application in phenol removal by RSM method

Journal of Materials Science: Materials in Electronics - Green synthesis of metal nanoparticles (NPs) has attracted a lot of attention in recent years because of lower costs and being...     

伊朗炎热干旱地区的建筑特征

伊朗历史荟萃了丰富的建筑杰作,比如萨删时代（540AD）的“Tagh—i—Kasra”以及那个年代建造的规模最大的墓穴。经过1400年前阿拉伯人的劫掠,那时曾经是索罗亚斯德教徒的伊朗人开始转而信仰伊斯兰教。这次转变造就了伊朗建筑与伊斯兰建筑的相互融合。该文探讨了伊朗建筑师在设计适合伊朗不同气候地区（如炎热干旱地区或温带和寒带地区）的建筑时所采用的可持续性传统方法,对建筑形式与环境的协调进行了重新解读,以期人们反思现代建筑与现代规划。     

Cell "vision": complementary factor of protein corona in nanotoxicology

Engineered nanoparticles are increasingly being considered for use as biosensors, imaging agents and drug delivery vehicles. Their versatility in design and applications make them an attractive proposition for new biological and biomedical approaches. Despite the remarkable speed of development in nanoscience, relatively little is known about the interaction of nanoscale objects with living systems. In a biological fluid, proteins associate with nanoparticles, and the amount and the presentation of the proteins on their surface could lead to a different in vivo response than an uncoated particle. Here, in addition to protein adsorption, we are going to introduce concept of cell "vision", which would be recognized as another crucial factor that should be considered for the safe design of any type of nanoparticles that will be used in specific biomedical applications. The impact of exactly the same nanoparticles on various cells is significantly different and could not be assumed for other cells; the possible mechanisms that justify this cellular response relate to the numerous detoxification strategies that any particular cell can utilize in response to nanoparticles. The uptake and defence mechanism could be considerably different according to the cell type. Thus, what the cell "sees", when it is faced with nanoparticles, is most likely dependent on the cell type.