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Guwahati, India

Jaisai M.,Asian Institute of Technology | Baruah S.,Asian Institute of Technology | Baruah S.,Assam Don Bosco University | Dutta J.,Asian Institute of Technology | Dutta J.,Sultan Qaboos University
Beilstein Journal of Nanotechnology

Paper with antimicrobial properties was developed through in situ growth of ZnO nanorods. The targeted application for this type of paper is in health centers as wallpaper, writing paper, facemasks, tissue paper, etc. The paper was tested on three model microbes, Gram-positive bacteria Staphylococcus aureus, Gram-negative bacteria Escherichia coli and common airborne fungus Aspergillus niger. No viable bacterial colonies or fungal spores could be detected in the areas surrounding test samples of the antimicrobial paper. Gram-negative bacteria Escherichia coli were found to be inhibited in an area that is 239% and 163% the area of the paper sample under different room lighting conditions, i.e., halogen and fluorescent lamp illumination, respectively. For Gram-positive bacteria Staphylococcus aureus the zones of inhibition surrounding the paper samples are 102% and 70%, and for Aspergillus niger, 224% and 183% of the sample area, under similar lighting conditions. © 2012 Jaisai et al. Source

Chettri S.K.,Assam Don Bosco University | Borah B.,Tezpur University
Innovations in Systems and Software Engineering

Time-series data analysis with privacy preservation is an open and challenging issue. To name a few are like analyzing company’s confidential financial data, individual’s health-related data, electricity consumption of individual’s households and so on. Due to the complex nature of time-series data, analyzing such data without any revelation of sensitive information to adversaries is a pervasive task. Here, we have addressed the issue of analyzing numerical time-series of equal length with preserved privacy. Considering the Discrete Wavelet Transform as a suitable technique for transforming time-series in frequency–time representation, we have applied the concept in privacy-preserving analysis of such data. Experimental results show that our proposed method is superior to the existing methods in preserving the trade-off between data utility and privacy. The privacy models developed using the proposed method are also evaluated in terms of clustering and classification accuracies obtained from perturbed time-series data. © 2015, Springer-Verlag London. Source

Deka R.K.,Gauhati University | Paul A.,Assam Don Bosco University
Computers and Fluids

A linear stability analysis for the Taylor-Dean flow, a viscous flow between concentric horizontal cylinders with a constant azimuthal pressure gradient, keeping the cylinders at different temperatures, when the inner cylinder is rotating and outer one is stationary has been implemented. The analysis is made under the assumption that the gap spacing between the cylinders is small compared to the mean radius. A parametric study covering wide ranges of β, a parameter characterizing the ratio of representative pumping and rotation velocities and N, the parameter characterizing the direction of temperature gradient is conducted. The eigenvalue problem is solved by differential transform method using unit disturbance scheme along with shooting technique. Emphasis is given to the occurrence of critical stability for the onset of instability by finding the intersection of the two neutral curves for the inner and outer part in a range of values of the radial temperature gradient parameter N,-1.25 Source

Baruah S.,Assam Don Bosco University
Lecture Notes in Electrical Engineering

Extensive use of fossil fuel in industries and automobiles has severely polluted the environment, adversely affecting the ecosystem. The fossil fuel reserves are also dwindling, creating a serious concern in the area of energy generation. With rapid advances in nanotechnology, researchers are putting in their efforts to exploit unique properties of nanomaterials to come up with environmentally friendly energy solutions. The abundantly freely available solar energy is undoubtedly the least utilized form of natural energy. Efficient tapping of solar energy can resolve the energy crisis that our world is currently going through. Solar cells developed using nanomaterials, though still at the infancy stage, will be able to harness solar energy quite efficiently and most importantly, will be able to do it very cheaply. Piezoenergy resulting from physical deformation of near-elastic crystals shows promise as energy source for self-powering of low energy consuming devices. This article discusses the possibility of using nanostructures of a very promising material, zinc oxide (ZnO), for energy generation. ZnO is a wide bandgap semiconductor (3.37 eV) and the absence of a central symmetry in its crystal endows it with piezoelectric property. This material has been successfully used for energy generation and tapping schemes like solar cells, hydrogen generators and piezogenerators, among others. © Springer India 2015. Source

Baruah S.,Assam Don Bosco University | Pal S.K.,se National Center For Basic Science | Dutta J.,Sultan Qaboos University
Nanoscience and Nanotechnology - Asia

Environmental pollution and industrialization on a global scale have drawn attention to the vital need for developing new hygienically friendly purification technologies. Existing wastewater treatment technologies demand high capital investment and operation & maintenance cost, and large area. Cost-effective treatment of pollutants requires the transformation of hazardous substances into benign forms and the subsequent development of effective risk management strategies from harmful effects of pollutants that are highly toxic, persistent, and difficult to treat. Application of nanotechnology that results in improved water treatment options might include removal of the finest contaminants from water (< 300 nm) and "smart materials" or "reactive surface coatings" with engineered specificity to a certain pollutant that destroy, transform or immobilize toxic compounds. Nanomaterials have been gaining increasing interest in the area of environmental remediation mainly due to their enhanced surface and also other specific changes in their physical, chemical and biological properties that develop due to size effects. Heterogeneous photocatalytic systems via metal oxide semiconductors like TiO2 and ZnO, are capable of operating effectively and efficiently for waste water treatment which has been discussed along with other nanotechnology routes that can be useful for water treatments. Multifunctional photocatalytic membranes using ZnO nanostructures are considered advantageous over freely suspended nanoparticles due to the ease of its removal from the purified water. A short discussion on the study of charge transfer mechanisms during photocatalytic reactions has also been included. © 2012 Bentham Science Publishers. Source

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