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Jeet K.,Panjab University | Jindal V.K.,Panjab University | Bharadwaj L.M.,Central Scientific Instruments Organisation | Bhandari R.,Postgraduate Government College | Dharamvir K.,Panjab University
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

A study on the structural evolution of carbon nanotubes (CNTs) under irradiation by swift heavy ions (SHIs) of widely varying electronic energy loss (S e) values is presented. The control over S e is exercised through the choice of ion species used for irradiation. The ion beams used are those of nickel and gold with energies 60 and 120 MeV, respectively. Structural changes in CNTs were investigated qualitatively using Raman spectroscopy. Results of irradiation indicate that the structural modifications of CNTs can be broadly divided in three stages. At very low fluences the process of healing occurs; at intermediate fluences damage to the surface of CNTs predominates and nano-graphitic formations are seen; at very high fluences, of the order of 1 × 10 14 ions/cm 2, the system becomes amorphous. The stable nature of single walled carbon nanotubes compared to multiwalled carbon nanotubes, is also established from the Raman spectroscopy results. © 2012 Elsevier B.V. All rights reserved. Source

Kumar R.,Central Scientific Instruments Organisation | Kumar R.,Indian Institute for Plasma Research

Schlieren is among the oldest and widely used optical techniques for detection of change in refractive index in transparent media. Present work demonstrates the effect of the position of schlieren element in the Airy pattern on the schlieren interferogram. It has been shown that the amplitude of the diffracted wave, starting from schlieren element and serving as an inbuilt reference beam for the schlieren diffraction interferometer, becomes maximum when schlieren element diffracts light from the Airy disk. Effect of F-number of the optical system on schlieren pattern is also demonstrated via observations on the amplitude of diffracted light. © 2010 Elsevier GmbH. All rights reserved. Source

Sharma B.K.,Central Scientific Instruments Organisation | Kumar A.,Central Scientific Instruments Organisation | Murthy V.M.,Kurukshetra University
Journal of the Geological Society of India

Identification of seismic events from continuously recorded seismic data inreal-time through a Digital Seismic Data Recording system is a difficult task. Despite the vast amount of research in this field, the signal processing and event parameters discrimination algorithms have not yet fully come of age. Presently, we have a wide spectrum of trigger algorithms, ranging from a very simple amplitude threshold type to the sophisticated ones based on pattern recognition approaches. Some of the other approaches use adaptive technique and neural network methods. Researchers are continuously making efforts for the development of algorithms using various techniques, which produce minimum false trigger. Some approaches have been reported which are accurate for detecting first phase of events and take minimum possible computational time. In this paper several approaches for detecting event signals in background noise are presented and their precision evaluation is discussed. © GEOL. SOC. INDIA. Source

Singh S.,Central Scientific Instruments Organisation | Singh S.,Panjab University | Jain D.V.S.,Panjab University | Singla M.L.,Central Scientific Instruments Organisation
Sensors and Actuators, B: Chemical

Composite of sol-gel and PVP stabilized gold nanoparticles has been synthesized chemically and is used as an immobilization matrix for tyrosinase enzyme. The composite was spin coated on ITO electrode which was then characterized for its optical and electrochemical behavior. Cyclic voltametric study of ITO/Sol-AuNPs composite electrode showed well defined redox couple for Fe+ ions which is due to high electro-conductivity supplied mainly by gold nanoparticle coverage. The capacitance and faradic current are found to be 6.0 × 10-5 mF and 3.172 × 10-4 A respectively. The analytical performance of composite based catechol biosensor has been evaluated as a function of catechol concentration, buffer concentration and buffer pH. The system showed linearity from 1.0 × 10-6 M to 6 × 10-6 M with sensitivity of 0.01 A/M and LOD as 3 × 10-7 M. Effect of presence of gallic acid, catechin and cresol have been studied using amperometry which showed that these species does not interfere with catechol estimation. © 2013 Elsevier B.V. Source

Aulakh N.S.,Central Scientific Instruments Organisation | Kaler R.S.,Thapar University

This paper presents an edge filtering technique based interrogator for fiber Bragg grating sensors with microbend attenuation compensation system. The interrogator uses reference fiber along with the fiber in which the grating is inscribed to mitigate the effect of microbend attenuation in determining the Bragg wavelength of the sensor. © 2010 Elsevier GmbH. All rights reserved. Source

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