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Regent Park, India

Ankamwar B.,University of Pune | Kamble V.,University of Pune | Sur U.K.,University of Pune | Santra C.,Netaji Nagar Day College
Applied Surface Science

The development of eco-friendly and cost-effective synthetic protocol for the preparation of nanomaterials, especially metal nanoparticles is an emerging area of research in nanotechnology. These metal nanoparticles, especially silver can play a crucial role in various catalytic reactions. The biosynthesized silver nanoparticles described here was very stable up to 6 months and can be further exploited as an effective catalyst in the chemical reduction of 4-nitrophenol to 4-aminophenol. The silver nanoparticles were utilized as an efficient surface-enhanced Raman scattering (SERS) active substrate using Rhodamine 6G as Raman probe molecule. We have also carried out systematic comparative studies on the catalytic efficiency of both silver and gold nanoparticles using UV-vis spectra to monitor the above reaction spectrophotometrically. We find that the reaction follows pseudo-first order kinetics and the catalytic activity can be explained by a simple model based on Langmuir-Hinshelwood mechanism for heterogeneous catalysis. We also find that silver nanoparticles are more efficient as a catalyst compare to gold nanoparticles in the reduction of 4-nitrophenol to 4-aminophenol, which can be explained by the morphology of the nanoparticles as determined by transmission electron microscopy. © 2016 Elsevier B.V. All rights reserved. Source

Garain S.,Jadavpur University | Jana S.,Jadavpur University | Jana S.,Netaji Nagar Day College | Sinha T.K.,Indian Institute of Technology Kharagpur | Mandal D.,Jadavpur University
ACS Applied Materials and Interfaces

We report an efficient, low-cost in situ poled fabrication strategy to construct a large area, highly sensitive, flexible pressure sensor by electrospun Ce3+ doped PVDF/graphene composite nanofibers. The entire device fabrication process is scalable and enabling to large-area integration. It can able to detect imparting pressure as low as 2 Pa with high level of sensitivity. Furthermore, Ce3+-doped PVDF/graphene nanofiber based ultrasensitive pressure sensors can also be used as an effective nanogenerator as it generating an output voltage of 11 V with a current density ∼6 nA/cm2 upon repetitive application of mechanical stress that could lit up 10 blue light emitting diodes (LEDs) instantaneously. Furthermore, to use it in environmental random vibrations (such as wind flow, water fall, transportation of vehicles, etc.), nanogenerator is integrated with musical vibration that exhibits to power up three blue LEDs instantly that promises as an ultrasensitive acoustic nanogenerator (ANG). The superior sensing properties in conjunction with mechanical flexibility, integrability, and robustness of nanofibers enabled real-time monitoring of sound waves as well as detection of different type of musical vibrations. Thus, ANG promises to use as an ultrasensitive pressure sensor, mechanical energy harvester, and effective power source for portable electronic and wearable devices. © 2016 American Chemical Society. Source

Bhattacharya D.,Jadavpur University | Santra C.R.,Netaji Nagar Day College | Ghosh A.N.,Indian National Institute of Cholera and Enteric Diseases | Karmakar P.,Jadavpur University
Journal of Biomedical Nanotechnology

The cytotoxic and genotoxic potential of rod and spherical zinc oxide nanoparticles (ZnO NPs) were evaluated on human peripheral blood mononuclear cells (PBMCs). Their sizes and shapes were determined by Transmission electron microscopy (TEM) and physical characterizations were done by X-ray diffraction (XRD) and Dynamic light scattering (DLS). The cytotoxic potential of rod ZnO NPs was greater than spherical ZnO NPs when applied to PBMCs and was limited to the proliferative lymphocytes. Rod ZnO NPs produced more reactive oxygen species (ROS) compared to spherical ones. Additionally rod ZnO NPs induced significant DNA damage to PBMCs as revealed by cytokinesis block micronucleus (CBMN) assay and comet assay. On the other hand UV absorption property was enhanced in case of spherical ZnO NPs compared to rod ZnO NPs. Thus, present study implicates the shape dependent differential application of ZnO NPs in our daily life. Copyright © 2014 American Scientific Publishers All rights reserved. Source

Chakraborty A.,Tata Institute of Fundamental Research | Ghosh D.K.,Indian Association for The Cultivation of Science | Mondal S.,Harish Chandra Research Institute | Poddar S.,Netaji Nagar Day College | Sengupta D.,CNRS Laboratory of Subatomic Physics & Cosmology
Physical Review D - Particles, Fields, Gravitation and Cosmology

Higgs signatures from the cascade decays of light top squarks are an interesting possibility in the next-to-minimal supersymmetric standard model (NMSSM). We investigate the potential reach of the light top-squark mass at the 13 TeV run of the LHC by means of five NMSSM benchmark points where this signature is dominant. These benchmark points are compatible with current Higgs coupling measurements, LHC constraints, dark matter relic density and direct-detection constraints. We consider single and dilepton search strategies, as well as the jet-substructure technique to reconstruct the Higgs bosons. We find that one can probe top-squark masses up to 1.2 TeV with 300fb-1 luminosity via the dilepton channel, while with the jet-substructure method, top-squark masses up to 1 TeV can be probed with 300fb-1 luminosity. We also investigate the possibility of the appearance of multiple Higgs peaks over the background in the fat-jet mass distribution, and conclude that such a possibility is viable only at the high-luminosity run of the 13 TeV LHC. © 2015 American Physical Society. Source

Datta A.,Indian Institute of Science | Datta A.,University of Calcutta | Poddar S.,Netaji Nagar Day College
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

We propose a new search strategy based on the event shape variables for new physics models where the separations among the masses of the particles in the spectrum are small. Collider signature of these models, characterized by low p T leptons/jets and low missing p T, are known to be difficult to look for. The conventional search strategies involving hard cuts may not work in such situations. As a case study, we have investigated the hitherto neglected jets+missing E T signature - known to be a challenging one - arising from the pair productions and decay of n=1 KK-excitations of gluons and quarks in the minimal Universal Extra Dimension (mUED) model. Judicious use of the event shape variables enables us to reduce the Standard Model backgrounds to a negligible level. We have shown that in mUED, R -1 up to 850GeV can be explored or ruled out with 12 fb -1 of integrated luminosity at the 7 TeV run of the LHC. We also discuss the prospects of employing these variables for searching other beyond Standard Model physics with compressed or partially compressed spectra. © 2012 Elsevier B.V. Source

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