Design of laminated composite structures for optimum fiber direction and layer thickness,using optimality criteria

In this study, two optimality criteria are presented for optimum design of composite laminates using finite element method. Thickness of the layers and fiber orientation angles in each finite element are considered as the design variables. It will be shown that the optimum design of composite laminates with varying fiber orientations and layers thicknesses may be found by using these optimality criteria in an efficient way, without performing the sensitivity analysis.     

Anti‐Oxygen Leaking LiCoO2

LiCoO₂ is a prime example of widely used cathodes that suffer from the structural/thermal instability issues that lead to the release of their lattice oxygen under nonequilibrium conditions and safety concerns in Li‐ion batteries. Here, it is shown that an atomically thin layer of reduced graphene oxide can suppress oxygen release from Li_xCoO₂ particles and improve their structural stability. Electrochemical cycling, differential electrochemical mass spectroscopy, differential scanning calorimetry, and in situ heating transmission electron microscopy are performed to characterize the effectiveness of the graphene‐coating on the abusive tolerance of Li_xCoO₂. Electrochemical cycling mass spectroscopy results suggest that oxygen release is hindered at high cutoff voltage cycling when the cathode is coated with reduced graphene oxide. Thermal analysis, in situ heating transmission electron microscopy, and electron energy loss spectroscopy results show that the reduction of Co species from the graphene‐coated samples is delayed when compared with bare cathodes. Finally, density functional theory and ab initio molecular dynamics calculations show that the rGO layers could suppress O₂ formation more effectively due to the strong C? O_cathode bond formation at the interface of rGO/LCO where low coordination oxygens exist. This investigation uncovers a reliable approach for hindering the oxygen release reaction and improving the thermal stability of battery cathodes.     

Highly luminescent film functionalized with CdTe quantum dots by layer‐by‐layer assembly

Robust and facile strategies are required to fabricate film with high luminescence for application in the fields of biomaterials. In this study, the luminescent electrospinning cellulose fibrous mats were decorated with CdTe quantum dots (QDs) and poly(diallyl dimethyl ammonium chloride) (PDDA) using layer by layer (LBL). The characterizations of the LBL films coated mats were executed by X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, fluorescent spectroscopy, X‐ray diffraction, thermal gravimetric analysis, and differential scanning calorimetry. The luminescent intensities were linearly increased with adding the amount of deposited bilayers. The green fabricated (QDs/PDDA)_n coated mat through physical interactions is a promising luminescent material. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41893.     

Two-dimensional spin coating with a vertical centrifugal force and the effect of artificial gravity on surface leveling

This study focuses on an innovative method for spin coating called the two-dimensional (2D) spin coating method. Using a centrifugal force applied by a rotary machine perpendicular to the wafer surface body, a vertical centrifuge force (VCF) was generated. The VCF allowed controllable artificial gravity acceleration to be generated and caused the coating to face this elevated gravity acceleration to adjust and normalize the high and low surface tension stresses. Previous surface leveling mathematics were analyzed and modified. The modified calculations indicate that the effect of additional gravity exerted on the liquid’s surface can reduce the amplitude of surface leveling. To experimentally investigate this phenomenon, a 2D spin coater was designed and manufactured. Higher artificial gravity overcame some common coating defects, such as cloudiness, edge beading, inner layer bubbling, and unsmooth surface leveling. Photoresist (AZP4620) was used as the coating material. The surface roughness was analyzed by atomic force microscopy (AFM) and the layer properties were also imaged by scanning electron microscopy (SEM). The AFM results (average and root-mean-square roughness) indicated a decrease in surface leveling amplitude by increasing the VCF. SEM images showed condensed layers without any porosity or rupture. The experimental results agreed with the simulations and calculated values.     

Dynamically vulcanized polypropylene/ethylene‐propylene diene monomer/organoclay nanocomposites: Effect of mixing sequence on structural,rheological, and mechanical properties

Dynamically vulcanized thermoplastic elastomer (TPE) nanocomposites based on polypropylene (PP), ethylene‐propylene diene monomer (EPDM) and cloisite 15A were prepared via direct melt mixing in a co‐rotating twin‐screw extruder. The mixing process was carried out with optimized processing parameters (barrel temperature = 180°C; screw speed = 150 rpm; and feeding rate = 0.2 kg/hr). The formulation used to prepare the nanocomposites was fixed to 75/20/5 (PP/EPDM/Cloisite^©15A), expressed in mass fraction. Effect of mixing sequence on the properties of vulcanized and unvulcanized (TPE) nanocomposites prepared under similar conditions was investigated using X‐ray diffraction (XRD) and a tensile testing machine. Results showed that the sequence of mixing does affect the properties of final TPE nanocomposites. Accordingly, nanocomposite samples prepared through mixing the preblended PP/clay masterbatch with EPDM phase, show better clay dispersion within the polymer matrix. J. VINYL ADDIT. TECHNOL., 22:320–325, 2016. © 2014 Society of Plastics Engineers     

Electrophoretic deposition of bioactive glass nanopowders on magnesium based alloy for biomedical applications

To slow down the initial biodegradation rate of magnesium (Mg) alloy, crystalline nano-sized bioactive glass coating was used to deposit on micro-arc oxidized AZ91 samples via electrophoretic deposition (EPD). Zeta potential and conductivity of the bioactive glass suspension were characterized at various pH values to identify the most stable dispersion conditions. The bone-bonding properties of bioactive glass coated samples were evaluated in terms of apatite-forming ability during the immersion in simulated body fluid (SBF) solution. Results revealed that the ability to form a bioactive glass coating via EPD was influenced by the degree of its crystalline phase composition. Moreover, the potentiodynamic polarization tests recorded significant drops in corrosion current density and corrosion rate of the coated samples which implies a good level of corrosion protective behavior. These preliminary results show that this process will enable the development of Mg implants in the later stage of bone healing.     

High-performance photocatalysts for the selective oxidation of alcohols to carbonyl compounds

With an increase in awareness about the need for green chemistry, there is a shift in focus towards identifying eco-compatible technologies that can improve product yield and eliminate the use or generation of hazardous compounds. An immediate practical example of such an approach is the development of sustainable methods for alcohol oxidation as alternatives to the current processes that are energy intensive and rely on ecotoxic chemicals. In this regard, heterogeneous photocatalysis has been identified as a robust technique to catalyze reactions under benign conditions, which would otherwise require harsh synthesis routes. With the advent of materials sciences and nanotechnology, there has been a tremendous increase in the scope of applicability of photocatalysis in fine chemicals synthesis. Though an attractive choice, much of the fundamental information pertaining to catalyst activity, selectivity and reaction conditions for optimum conversion are still to be investigated for most of these systems. To this end, this review will encompass recent achievements in the selective photocatalytic oxidation of alcohols by harnessing solar radiation as a viable source of energy. The discussion will be arranged based on common types of photocatalysts reported in literature, namely metal oxides (eg, TiO₂ and ZnO, Nb₂O₅), sulphides (eg, CdS, CuS, and Bi₂S₃), and carbonaceous photocatalysts (eg, g-C₃N₄). Several such candidates for photocatalysts will be discussed critically with the aim of providing useful insight into developing selective photocatalysts that can oxidize alcohols via eco-friendly pathways along with high yields.     

Phosphorus Removal from Si-Fe Alloy Using SiO2-Al2O3-CaO Slag

Metallurgical and Materials Transactions B - Phosphorus removal from silicon using a combination of solvent and slag refining, with lower carbon footprint and lower energy requirement than the...     

The effects of gradual replacement of barley with oats on enteric methane emissions,rumen fermentation,milk production,and energy utilization in dairy cows

This study evaluated the effects of gradual replacement of barley with oats on enteric CH₄ emissions, rumen fermentation, diet digestibility, milk production, and energy utilization in dairy cows fed a grass silage-based diet. Sixteen lactating Nordic Red dairy cows received a total mixed ration [58:42 forage:concentrate on dry matter (DM) basis]. Grass silage (Phleum pratense) was the sole forage with canola meal (10% of diet DM) as a protein supplement. The effects of gradual replacement of barley with oats on DM basis were evaluated using a replicated 4 × 4 Latin square design with 21 d periods. The grain supplements (30% of diet DM) consisted of 100% barley, 67% barley and 33% oats, 33% barley and 67% oats, and 100% oats. In addition to intake, milk production, and digestibility measurements, CH₄ emissions were measured by the GreenFeed system (C-Lock Inc.). The energy metabolism was estimated from the gas exchange measurements recorded by the GreenFeed unit. The last 10 d of each period were used for recordings of gas exchanges, feed intake and milk production. Dry matter intake, body weight, milk yield, and energy-corrected milk yield were not affected by gradual replacement of barley with oats in the diet. Increased inclusion of oats linearly decreased CH₄ emissions from 467 to 445 g/d, and CH₄ intensity from 14.7 to 14.0 g/kg energy-corrected milk. In addition, the ratio of CH₄ to CO₂ decreased with increasing inclusion of oats in the diet. Digestibility of organic matter, neutral detergent fiber, and potentially digestible neutral detergent fiber decreased linearly with increasing inclusion of oats. Increased inclusion of oats linearly increased fecal energy from 121 to 133 MJ/d, whereas urinary energy and heat production were not affected by dietary treatment. This resulted in a linear decrease in metabolizable energy intake. However, increased levels of oat in the diet did not significantly affect energy balance or efficiency of metabolizable energy utilization for lactation. This study concludes that barley could be replaced with oats in the diet of dairy cows fed a grass silage-based diet to mitigate CH₄ emissions without having any adverse effects on productivity or energy balance. However, the effect of replacing barley with oats on CH₄ emissions is dependent on the differences between barley and oats in the concentrations of indigestible neutral detergent fiber and fat.     

Saffron (Crocus sativus L.) increases glucose uptake and insulin sensitivity in muscle cells via multipathway mechanisms

Saffron (Crocus sativus Linn.) has been an important subject of research in the past two decades because of its various biological properties, including anti-cancer, anti-inflammatory, and anti-atherosclerotic activities. On the other hand, the molecular bases of its actions have been scarcely understood. Here, we elucidated the mechanism of the hypoglycemic actions of saffron through investigating its signaling pathways associated with glucose metabolism in C₂C₁₂ skeletal muscle cells. Saffron strongly enhanced glucose uptake and the phosphorylation of AMPK (AMP-activated protein kinase)/ACC (acetyl-CoA carboxylase) and MAPKs (mitogen-activated protein kinases), but not PI 3-kinase (Phosphatidylinositol 3-kinase)/Akt. Interestingly, the co-treatment of saffron and insulin further improved the insulin sensitivity via both insulin-independent (AMPK/ACC and MAPKs) and insulin-dependent (PI 3-kinase/Akt and mTOR) pathways. It also suggested that there is a crosstalk between the two signaling pathways of glucose metabolism in skeletal muscle cells. These results could be confirmed from the findings of GLUT4 translocation. Taken together, AMPK plays a major role in the effects of saffron on glucose uptake and insulin sensitivity in skeletal muscle cells. Our study provides important insights for the possible mechanism of action of saffron and its potential as a therapeutic agent in diabetic patients.