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Soni S.,Indian Institute of Technology Ropar | Tyagi H.,Indian Institute of Technology Ropar | Taylor R.A.,University of New South Wales | Kumar A.,Central Scientific Instruments Organisation
International Journal of Hyperthermia | Year: 2015

Purpose: This study investigates the influence of blood perfusion variability within a tumour and the surrounding healthy tissue during nanoparticle-assisted thermal therapy. It seeks to define ideal therapeutic parameters for a wide range of perfusion rates to attain the desired thermal damage. Material and methods: Pennes bioheat model and the Arrhenius model are used to evaluate the thermal damage for a two-dimensional tumour surrounded by healthy tissue. A wide range of tumour perfusion rates were modelled, ranging from moderate to high perfusion in both a homogenously and a heterogeneously perfused tumour. Results: For low perfusion rates, a temporal variation in blood perfusion does not critically influence the thermal damage. For moderately and highly perfused tumours, temporal variation in blood perfusion extends the thermal damage zone by 25-52% compared to a constant perfusion rate. For the tumour size and perfusion conditions under consideration, the ideal therapeutic parameters were found to be irradiation intensity of 1 W/cm2, and irradiation duration of 105-150 s, for a nanoparticle volume fraction of 0.001%. Conclusions: It is concluded for low perfusion rates that due to shorter therapeutic duration, nanoparticle-assisted thermal therapy is relatively insensitive to changes in the perfusion rate during the therapy. For moderately and highly perfused tumours, a constant perfusion under-predicts the real thermal damage zone. This study concludes that for moderately and highly perfused tumours the spatial as well as temporal blood perfusion dynamics should be carefully accounted for to get a realistic estimate of thermal damage zone. © 2015 © 2015 Informa UK Ltd.

Kumar S.,Thapar University | Verma N.K.,Thapar University | Singla M.L.,Central Scientific Instruments Organisation
Journal of Coatings Technology Research | Year: 2011

In the present paper, the authors report having developed highly reflective and durable coatings using synthesized zinc sulfide-capped thioglycerol nanoparticles. The coating material was prepared by dispersing ZnS/thioglycerol nanoparticles in an acrylic binder. The light reflectors were made applying this coating material to an aluminum substrate; their diffuse reflectance was measured and found to vary from 97% to 100% for 0.30-mm thick coating having 14% pigment-to-binder ratio. The aging effect of the reflectors with respect to temperature and illumination was also investigated to check their durability and they have been found to be optically stable up to 10,000 lux, and thermally up to 80°C. © ACA and OCCA 2010.

Aulakh N.S.,Central Scientific Instruments Organisation | Kaler R.S.,Thapar University
Optik | Year: 2011

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.

Kumar S.,Thapar University | Verma N.K.,Thapar University | Singla M.L.,Central Scientific Instruments Organisation
Digest Journal of Nanomaterials and Biostructures | Year: 2012

The present work investigates the size dependent reflective properties of TiO2 nanoparticles and discusses the development of reflectors. The nanocrystalline TiO2 powders with different crystallinity and phase structures were obtained by controlling the reaction parameters. TiO2 nanoparticles synthesized via sol-gel method were characterized by using X-ray diffraction (XRD), transmission electron microscope (TEM), UV-Vis absorption fluorospectrophotometer and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). Rutile phase TiO2 nanoparticles with crystallite sizes in the range, 77.50 - 78.31 nm, were obtained by adjusting the L value in the range 20 to 50. On calcining the TiO2 powders from 350°C to 900°C, the particle size increases from 60 to 150 nm and band gap energy decreases from 3.42 to 3.14 eV, calculated respectively using TEM micrograph and UV-Vis absorption spectra. PL spectrum shows a broad luminescence peak at 431 nm, irrespective of the different calcination temperatures. TiO2 nanoparticles with L value of 40 shows the attainment of maximum diffuse reflectance (99.50 - 99.60%). Employing these nanoparticles as reflective pigment, coating material was prepared and applied on plastic substrate with different coating thicknesses to develop reflectors. These reflectors show maximum diffuse reflectance, 97.12 - 96.91%, for the 0.25-mm thick coating with 17% pigment to binder weight ratio.

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 | Year: 2012

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.

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 | Year: 2010

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.

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 | Year: 2013

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.

Arora S.,Central Scientific Instruments Organisation | Kapoor P.,Panjab University | Singla M.L.,Central Scientific Instruments Organisation
Reaction Kinetics, Mechanisms and Catalysis | Year: 2010

In this study, a high catalytic activity of palladium nanoparticles immobilized on alumina (Al 2O 3) is reported for the industrially important reduction of aromatic nitro compounds to amino compounds. The palladium nanoparticles were immobilized on alumina by a simple physical precipitation method. The synthesis of palladium nanoparticles was done in ethylene glycol without using any external stabilizing agent. The composite particles exhibited good colloidal stability. The catalytic activity is investigated qualitatively by high performance liquid chromatography (HPLC) and quantitatively by photometrically monitoring the reduction of p-nitrophenol by an excess of sodium borohydride (NaBH 4) in the presence of nanocomposites. The kinetic data could be explained by the assumption of pseudo first-order reaction with respect to p-nitrophenol. © Akadémiai Kiadó , Budapest, Hungary 2010.

Kumar R.,Central Scientific Instruments Organisation | Kumar R.,Indian Institute for Plasma Research
Optik | Year: 2011

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.

Guha P.,Central Scientific Instruments Organisation | Mishra S.,Central Scientific Instruments Organisation
International Journal of Automation and Computing | Year: 2014

This paper considers the problem of simulating the humidity distributions of a grain storage system. The distributions are described by partial differential equations (PDE). It is quite difficult to obtain the humidity profiles from the PDE model. Hence, a discretization method is applied to obtain an equivalent ordinary differential equation model. However, after applying the discretization technique, the cost of solving the system increases as the size increases to a few thousands. It may be noted that after discretization, the degree of freedom of the system remain the same while the order increases. The large dynamic model is reduced using a proper orthogonal decomposition based technique and an equivalent model but of much reduced size is obtained. A controller based on optimal control theory is designed to obtain an input such that the output humidity reaches a desired profile and also its stability is analyzed. Numerical results are presented to show the validity of the reduced model and possible further extensions are identified. © 2014 Institute of Automation, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg.

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