New composites based on short melamine fiber reinforced epdm rubber

Melamine fibre is a new category of advanced synthetic fiber having superior heat and flame resistance with decomposition temperature above 350°C. It suitability as a reinforcing fiber for ethylene propylene diene terpolymer, abbreviated as EPDM rubber, where ‘M’ stands for polymethylene chain, was investigated. It has been observed that tensile strength and stress at 100% strain of EPDM‐melamine fiber composites increase with the addition of a three‐component dry bonding system, comprising hexamethylene tetramine (hexa), resorcinol, and hydrate silica, abbreviated HRH system. Moreover, the fiber‐filled composites anisotropy in stress‐strain properties due to preferential of the short fibers along the milling direction (longitudinal), which is substantiated by the results of swelling and fractography studies. Aging causes an increase in the modulus, tensile strength and hardness of the composites. The fractographs show an increase in interfacial adhesion between the fibers and the matrix during aging, which is further confirmed by the reduction in tan δ peak height of the aged composites during dynamic mechanical studies. Atomic Force Microscopy (AFM) studies reveal the formation of an interphase with the addition of bonding agents and a better fiber‐matrix adhesion due to aging. AFM images also confirm the role of dry bonding systems in improving the fiber‐matrix adhesion of the aged vulcanizates. The composite modulus has been theoretically calculated using the well‐known Halpin‐Tsai equation. It is found that in the transverse direction, observed modulus values are greater than the calculated values, while in the longitudinal direction, the experimental modulus values are found to be lower than the calculated values for both unaged and aged composites owing to some degree of anisotropy in fiber orientation.     

Study of Corrosion Behavior and In Vitro Bioactivity of Single NbSi2 and Duplex NbSi2/Nb5Si3 Coatings on Nb Substrates for Biomedical Applications

Protection of Metals and Physical Chemistry of Surfaces - Single NbSi2 and duplex NbSi2/Nb5Si3 coatings were successfully applied on Nb substrates using halide activated pack cementation (HAPC)...     

Antioxidant capacity and phenolic content of selected tropical fruits from Malaysia,extracted with different solvents

The antioxidant capacity and phenol content of three tropical fruits pulps, namely, honey pineapple, banana and Thai seedless guava, were studied. Three solvent systems were used (methanol, ethanol and acetone) at three different concentrations (50%, 70% and 90%) and with 100% distilled water. The antioxidant capacity of the fruit extracts was evaluated using a ferric reducing/antioxidant power assay and the free radical-scavenging capacity was evaluated using 2,2-diphenyl-1-picrylhydrazyl radical-scavenging assays. The efficiency of the solvents used to extract phenols from the three fruits varied considerably. The polyphenol content of Thai seedless guava was 123 to 191 gallic acid equivalents/100 g (GAE/100 g), that of pisang mas was 24.4 to 72.2 GAE/100 g, and that of honey pineapple was 34.7 to 54.7 GAE/100 g. High phenol content was significantly correlated with high antioxidant capacity.     

Carbon nanotube-DNA nanoarchitectures and electronic functionality

Biological molecules such as deoxyribonucleic acid (DNA) possess inherent recognition and self-assembly capabilities, and are attractive templates for constructing functional hierarchical material structures as building blocks for nanoelectronics. Here we report the assembly and electronic functionality of nanoarchitectures based on conjugates of single-walled carbon nanotubes (SWNTs) functionalized with carboxylic groups and single-stranded DNA (ssDNA) sequences possessing terminal amino groups on both ends, hybridized together through amide linkages by adopting a straightforward synthetic route. Morphological and chemical-functional characterization of the nanoarchitectures are investigated using scanning electron microscopy, transmission electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. Electrical measurements (I-V characterization) of the nanoarchitectures demonstrate negative differential resistance in the presence of SWNT/ssDNA interfaces, which indicates a biomimetic route to fabricating resonant tunneling diodes. I-V characterization on platinum-metallized SWNT-ssDNA nanoarchitectures via salt reduction indicates modulation of their electrical properties, with effects ranging from those of a resonant tunneling diode to a resistor, depending on the amount of metallization. Electron transport through the nanoarchitectures has been analyzed by density functional theory calculations. Our studies illustrate the great promise of biomimetic assembly of functional nanosystems based on biotemplated materials and present new avenues toward exciting future opportunities in nanoelectronics and nanobiotechnology.     

Efficient ID-based proxy multi-signature scheme secure in random oracle

Proxy signature schemes enable an entity to delegate its signing rights to any other party, called proxy signer. As a variant of proxy signature primitive, proxymultisignature allows a group of original signers to delegate their signing capabilities to a single proxy signer in such a way that the proxy signer can sign a message on behalf of the group of original signers. We propose a concrete ID-based proxy multi-signature scheme from bilinear pairings. The proposed scheme is existential unforgeable against adaptively chosen message and given ID-attack in random oracle model under the computational Diffie-Hellman (CDH) assumption. The fascinating property of new scheme is that the size of a proxy multi-signature is independent of the number of original signers. Furthermore the proposed scheme is simple and computationally more efficient than other ID-based proxy multisignature schemes.     

Evaluation of processed green and ripe mango peel and pulp flours (Mangifera indica var. Chokanan) in terms of chemical composition,antioxidant compounds and functional properties

BACKGROUND: Mango is a highly perishable seasonal fruit and large quantities are wasted during the peak season as a result of poor postharvest handling procedures. Processing surplus mango fruits into flour to be used as a functional ingredient appears to be a good preservation method to ensure its extended consumption. RESULTS: In the present study, the chemical composition, bioactive/antioxidant compounds and functional properties of green and ripe mango (Mangifera indica var. Chokanan) peel and pulp flours were evaluated. Compared to commercial wheat flour, mango flours were significantly low in moisture and protein, but were high in crude fiber, fat and ash content. Mango flour showed a balance between soluble and insoluble dietary fiber proportions, with total dietary fiber content ranging from 3.2 to 5.94 g kg^?1. Mango flours exhibited high values for bioactive/antioxidant compounds compared to wheat flour. The water absorption capacity and oil absorption capacity of mango flours ranged from 0.36 to 0.87 g kg^?1 and from 0.18 to 0.22 g kg^?1, respectively. CONCLUSION: Results of this study showed mango peel flour to be a rich source of dietary fiber with good antioxidant and functional properties, which could be a useful ingredient for new functional food formulations. Copyright © 2011 Society of Chemical Industry     

Influence of temperature variations on growth,injury survival and inactivation of Listeria monocytogenes in goat milk samples at laboratory scale

Transmission of the thermo‐tolerant pathogen Listeria monocytogenes via contaminated milk and its products, can lead to serious food‐borne illness. In this study, the effects of selected temperatures on survival, percentage injury and inactivation of L. monocytogenes in goat milk samples collected from two different farms were evaluated. Low temperature ranges (0, 5, 10 °C) had a bacteriostatic effect; while at temperatures of 25 and 45 °C, this pathogen grew luxuriantly. However, growth was comparatively slow at 15 °C throughout a 12‐h stress period. Furthermore, a high temperature range (50, 55, 60 and 65 °C) resulted in the elimination of this pathogen within 4 h of stress. Results of Scanning Electron Microscopy showed morphological changes in the cells upon induction of stress temperatures.     

Freezing-induced splashing during impact of molten metal droplets with high Weber numbers

The impact of molten tin droplets (0.6 mm diameter) on solid surfaces was observed for a range of impact velocities (10–30 m/s), substrate temperatures (25–200 °C) and substrate materials (stainless steel, aluminum and glass). The substrate was mounted on the rim of a rotating flywheel and the collision of single droplets with the moving substrate was photographed. Droplet impact Reynolds number ranged from 2.2 × 10⁴ to 6.5 × 10⁴ and Weber number from 8.0 × 10² to 7.2 × 10³. On a hot surface there was no splashing and droplets spread to form disk-like splats with smooth edges. Solidification around the edges of droplets spreading on cold surfaces created a solid rim that obstructed flow and triggered splashing. An analytical model was developed to predict the transition temperature at which splashing disappeared by assuming that the thickness of the solid layer had to equal that of the splat in the time the droplet spread to its maximum extent in order to obstruct liquid flow. The model predicted the transition temperature for aluminum and stainless steel surfaces, assuming that thermal contact resistance between the droplet and substrate varied between 10⁻⁶ and 10⁻⁷ m² K/W. The model also predicted that tin droplets would not splash on glass surfaces maintained at or above room temperature, and this was confirmed by experiments.     

The use of rigid gas permeable contact lenses in children with myopic amblyopia: A case series

Purpose

To explore the safety profile and overall visual improvement over the course of RGP contact lens wear on children with unilateral or bilateral amblyopia resulting from myopia.