Poly(N-vinylpyrrolidone)-stabilized colloidal graphene-reinforced poly(ethylene-co-methyl acrylate) to mitigate electromagnetic radiation pollution

Polymer Bulletin - Electrically conducting flexible polymeric nanocomposite has been fabricated through wet mixing method where conducting inclusion was acoustically exfoliated pristine graphene...     

Clock Distribution Methodology for PowerPC? Microprocessors

Clock distribution design for high performance microprocessors has become increasingly challenging in recent years. Design goals of state-of-the-art integrated circuits, dictate the need for clock networks with smaller skew tolerances, large sizes, and lower capacitances. In this paper we discuss some of the issues in clock network design that arise in this context. We describe the clock design methodology and techniques used in the design of clock distribution networks for PowerPC microprocessors that aim at alleviating some of these problems.     

Exploitation of Social Media for Emergency Relief and Preparedness: Recent Research and Trends

Online Social Media, such as Twitter, Facebook and WhatsApp, are important sources of real-time information related to emergency events, including both natural calamities, man-made disasters, epidemics, and so on. There has been lot of recent work on designing information systems that would be useful for aiding post-disaster relief operations, as well as for pre-disaster preparedness. A special issue on “Exploitation of Social Media for Emergency Relief and Preparedness” was conducted for the journal Information Systems Frontiers. The objective of this special issue was to present a platform for dissemination of the empirical results of various technologies for extracting vital and actionable information from social media content in disaster situations. The papers included in this issue are expected to be the stepping stones for future explorations and technical innovations towards technologies meant for utilizing various online and offline information sources for enhancing pre-disaster preparedness and post-disaster relief operations.     

Classifying and Summarizing Information from Microblogs During Epidemics

During a new disease outbreak, frustration and uncertainties among affected and vulnerable population increase. Affected communities look for known symptoms, prevention measures, and treatment strategies. On the other hand, health organizations try to get situational updates to assess the severity of the outbreak, known affected cases, and other details. Recent emergence of social media platforms such as Twitter provide convenient ways and fast access to disseminate and consume information to/from a wider audience. Research studies have shown potential of this online information to address information needs of concerned authorities during outbreaks, epidemics, and pandemics. In this work, we target three types of end-users (i) vulnerable population—people who are not yet affected and are looking for prevention related information (ii) affected population—people who are affected and looking for treatment related information, and (iii) health organizations—like WHO, who are interested in gaining situational awareness to make timely decisions. We use Twitter data from two recent outbreaks (Ebola and MERS) to build an automatic classification approach useful to categorize tweets into different disease related categories. Moreover, the classified messages are used to generate different kinds of summaries useful for affected and vulnerable communities as well as health organizations. Results obtained from extensive experimentation show the effectiveness of the proposed approach.     

Charge density and bare surface barrier height in GaN/AlGaN/GaN heterostructures: A modeling and simulation study

In this article, we present a physics‐based model to explain the effect of the GaN cap layers on the 2D electron gas density and the bare surface barrier height in AlGaN/GaN heterostructures. We consider that the 2DEG originates from the surface donor states present on the GaN cap top surface. The influence of a 2D hole gas, formed when the valence band crosses the Fermi energy level, has also been considered. This model agrees well with the published experimental results and TCAD simulations, and can easily be incorporated into the modeling of GaN/AlGaN/GaN‐based HEMT devices.     

Alginate‐gelatin blend with embedded voids for controlled release applications

Alginate gel is known for its potential use in the controlled release of drugs, and as a 3‐D structure for tissue harvesting. In this paper, the tuning of the performance of alginate gel by blending gelatin in the aqueous phase, and introducing bubbles in a regular alignment are discussed. Monodisperse bubbles in millimetre or submillimeter size were introduced into the aqueous suspension of the blend prior to gelation, using a novel fluidic arrangement. The CaCl₂ solution, added as the crosslinker diffused into the lamella, forming a rigid structure of calcium alginate. The effective blending of gelatin in alginate provided benefits of both the biopolymers in the final product. The benefits are the excellent absorption capacity of alginate and the mechanical strength of gelatin in the blend. The self‐aligned voids enabled further tuning of absorption capacity and/or rate of release. Also, the presence of voids enhanced the elastomeric quality of the composite structure. The uptake of Vitamin B₁₂ solution was measured gravimetrically, and the release in PBS buffer on a shaker was studied using UV‐vis spectrophotometer. For different loadings of void and gelatin, the absorption capacity, mechanical strength and the compression behavior were analysed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44787.     

Symmetric coupling of multi‐zone curved Galerkin boundary elements with finite elements in elasticity

The coupling of Finite Element Method (FEM) with a Boundary Element Method (BEM) is a desirable result that exploits the advantages of each. This paper examines the efficient symmetric coupling of a Symmetric Galerkin Multi‐zone Curved Boundary Element Analysis method with a Finite Element Method for 2‐D elastic problems. Existing collocation based multi‐zone boundary element methods are not symmetric. Thus, when they are coupled with FEM, it is very difficult to achieve symmetry, increasing the computational work to solve the problem. This paper uses a fully Symmetric curved Multi‐zone Galerkin Boundary Element Approach that is coupled to an FEM in a completely symmetric fashion. The symmetry is achieved by symmetrically converting the boundary zones into equivalent ‘macro finite elements’, that are symmetric, so that symmetry in the coupling is retained. This computationally efficient and fast approach can be used to solve a wide range of problems, although only 2‐D elastic problems are shown. Three elasticity problems, including one from the FEM‐BEM literature that explore the efficacy of the approach are presented. Copyright © 2000 John Wiley & Sons, Ltd.     

A fully symmetric multi‐zone Galerkin boundary element method

This paper examines the efficient integration of a Symmetric Galerkin Boundary Element Analysis (SGBEA) method with multi‐zone resulting in a fully symmetric Galerkin multi‐zone formulation. In a previous approach, a Galerkin multi‐zone method was developed where the interfacial nodes are assigned degrees of freedom globally so that the displacement and traction continuity across the zonal interfaces are addressed directly. However, the method was only block symmetric. In the present paper, two new approaches are derived. In the first approach, the degrees of freedom for a particular zone are assigned locally, independent of the other zones. The usual linear set of equations, from the symmetric Galerkin approach, are augmented with an additional set of equations generated by the Galerkin form of hypersingular boundary integrals along the interfaces. Zonal continuity is imposed externally through Lagrange's constraints. This approach is also only block symmetric. The second approach derived from the first, uses the continuity constraints at the zonal assembly level to achieve full symmetry. These methods are compared to collocation multi‐zone and an earlier formulation, on two elasticity problems from the literature. It was found that the second method is much faster than the collocation method for medium to large scale problems, primarily due to its complete symmetry. It is also observed that these methods spend marginally more time on integration than the previous Galerkin multi‐zone method but are better suited to parallel processing. Copyright © 1999 John Wiley & Sons, Ltd.     

Synthesis, characterization, photophysical properties of a novel organic photoswitchable dyad in its pristine and hybrid nanocomposite forms

In the present paper the method of synthesis and characterization of a novel organic dyad, 3-(1-Methoxy-3,4-dihydro-naphthalyn-2-yl-)-1-p-chlorophenyl propenone, have been reported. In this paper our main thrust is to fabricate new hybrid nanocomposites by combining the organic dyad with different noble metals, semiconductor nanoparticle and noble metal-semiconductor core/shell nanocomposites. In this organic dyad, donor part is 1-Methoxy-3, 4-dihydro-naphthalen-2-carboxaldehyde with the acceptor p-chloroacetophenone. We have carried out steady state and time-resolved spectroscopic measurements on the dyad and its hybrid nanocomposite systems. Some quantum chemical calculations have also been done using Gaussian 03 software to support the experimental findings by theoretical point of view. Both from the theoretical predictions and NMR studies it reveals that in the ground state only extended (E-type or trans-type) conformation of the dyad exists whereas on photoexcitation these elongated conformers are converted into folded forms (Z- or cis-type) of the dyad, showing its photoswitchable character. Time resolved fluorescence spectroscopic (fluorescence lifetime by TCSPC method) measurements demonstrate that in chloroform medium all the organic-inorganic hybrid nanocomposites, studied in the present investigation, possess larger amount of extended conformers relative to folded ones, even in the excited singlet state. This indicates the possibility of slower energy destructive charge recombination rates relative to the rate processes associate with charge-separation within the dyad. It was found that in CHCl3 medium, the computed charge separation rate was found to be approximately 10(8) s(-1) for the dyad alone and other hybrid nanocomposite systems. The rate is found to be faster than the energy wasting charge recombination rate approximately 10(2)-10(1) s(-1), as observed from the transient absorption measurements for the corresponding hybrid systems. It indicates the conformational geometry has a great effect on the charge-separation and recombination rate processes. The suitability for the construction of efficient light energy conversion devices especially with Ag-Dyad nanocomposite of all the systems studied here is hinted from the observed long ion-pair lifetime.