ENHANCED HYDROCARBON EXTRACTION FROM CALOTROPIS PROCERA - A PETROCROP

With fast disappearing petroleum reserves renewable resources like biomass are of great significance. Petrocrop, Calotropis procera is a wild shrub and does not compete with food and fodder crops for land. This paper presents an investigation on enhancement of hydrocarbon extraction from Calotropis procera. An extraction yield of 8% has been obtained with toluene, as solvent. Increase in extraction to 11.5% has been achieved by modification of design of conventional “Soxhlet extractor”. Further enhancement in extraction has been achieved by pre-treatment of the biomass with alkali or acid. Pre-treatment results in extractive or hydrolytic breakdown of plant structure and hence exposes hyrocarbons to solvent attack. Alkali pretreatment of ground biomass resulted in much higher extraction. So it was studied in further detail with more alkalies of varying strength. An enhancement from 8% to 18% has been achieved by pre-treatment with IN sodium hydroxide.     

New difference reflectance methods for study of small interfacial effects

Two sensitive differential optical techniques useful for study of small reflectance or absorptive differences between two interfaces are described. The first scheme employs a mechanically chopped light beam impinging on an arrangement of symmetrical dual cells to allow detection of differential reflectances DeltaR/R<10(-3). The second is a polarization-modulated beam-split laser version of the same method yielding approximately the same sensitivity. Representative measurements of voltage-induced reflectance changes at liquid-solid interfaces using these methods are given.     

Excellent electromagnetic interference shielding and mechanical properties accomplished in a manganese dioxide decorated graphene/polymer composite

In this work, we have incorporated pristine graphene and graphene sheets decorated with α and δ forms of manganese dioxide in a hydrogenated nitrile butadiene rubber matrix to obtain high-performance composites. The dual mixing technique was adopted to fabricate the composites having enhanced tensile, dielectric, and electromagnetic interference (EMI) shielding properties. The pristine graphene was introduced at various loadings, however, the α and δ manganese dioxide doped graphene was integrated at a single 8 phr concentration onto the rubber matrix. At an optimized concentration of 8 phr graphene in the matrix, a 101% increase in the tensile strength was observed compared to the unfilled rubber. An excellent improvement in the dielectric properties and a high EMI shielding value of 24.5 dB was observed for the15 phr loaded composite having a thickness of 2 mm. The composites should principally find applications as a robust and lightweight EMI shielding material.     

Security and performance enhancement of AODV routing protocol

A mobile ad hoc networks (MANET) is a decentralized, self‐organizing, infrastructure‐less network and adaptive gathering of independent mobile nodes. Because of the unique characteristics of MANET, the major issues to develop a routing protocol in MANET are the security aspect and the network performance. In this paper, we propose a new secure protocol called Trust Ad Hoc On‐demand Distance Vector (AODV) using trust mechanism. Communication packets are only sent to the trusted neighbor nodes. Trust calculation is based on the behaviors and activities information of each node. It is divided in to trust global (TG) and trust local (TL). TG is a trust calculation based on the total of received routing packets and the total of sending routing packets. TL is a comparison between total received packets and total forwarded packets by neighbor node from specific nodes. Nodes conclude the total trust level of its neighbors by accumulating the TL and TG values. The performance of Trust AODV is evaluated under denial of service/distributed denial of service (DOS/DDOS) attack using network simulator NS‐2. It is compared with the Trust Cross Layer Secure (TCLS) protocol. Simulation results show that the Trust AODV has a better performance than TCLS protocol in terms of end‐to‐end delay, packet delivery ratio, and overhead. Next, we improve the performance of Trust AODV using ant algorithm. The proposed protocol is called Trust AODV + Ant. The implementation of ant algorithm in the proposed secure protocol is by adding an ant agent to put the positive pheromone in the node if the node is trusted. Ant agent is represented as a routing packet. The pheromone value is saved in the routing table of the node. We modified the original routing table by adding the pheromone value field. The path communication is selected based on the pheromone concentration and the shortest path. Trust AODV + Ant is compared with simple ant routing algorithm (SARA), AODV, and Trust AODV under DOS/DDOS attacks in terms of performance. Simulation results show that the packet delivery ratio and throughput of the Trust AODV increase after using ant algorithm. However, in terms of end‐to‐end delay, there is no significant improvement. Copyright © 2014 John Wiley & Sons, Ltd.     

Electronic properties of molecular memory circuits on a nanoscale scaffold

Significant challenges exist in assembling and interconnecting the building blocks of a nanoscale device and being able to electronically address or measure responses at the molecular level. Here we demonstrate the usefulness of engineered proteins as scaffolds for bottom-up self-assembly for building nanoscale devices out of multiple components. Using genetically engineered cowpea mosaic virus, modified to express cysteine residues on the capsid exterior, gold nanoparticles were attached to the viral scaffold in a specific predetermined pattern to produce specific interparticle distances. The nanoparticles were then interconnected using thiol-terminated conjugated organic molecules, resulting in a three-dimensional network. Network properties were engineered by using molecular components with different I-V characteristics. Networks consisting of molecular wires alone were compared with networks containing voltage controlled molecular switches with two stable conductance states. Using such bistable molecules enabled the formation of switchable molecular networks that could be used in nanoscale memory circuits.