Alok Srivastava

Panjab University, Chandigarh, Chandigarh, India

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Publications (29)

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    Arjun Singh · Alok Srivastava · S. K. Gupta · [...] · A. Acharya
    [Show description] [Hide description] DESCRIPTION: It has been pointed out by number of researchers that polymers modified by ionizing radiation can also be used for commercial and defense related applications due to the extra stability brought about in their structural and thermal properties as a result of energy deposited into their polymeric matrix by ionizing radiation
    Full-text Research · Jul 2016
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    Dataset: Paper-1
    Arjun Singh · Alok Srivastava · S. K. Gupta · [...] · A. Acharya
    Full-text Dataset · Jul 2016
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    R. Patnaik · S. Lahiri · V. Chahar · [...] · Alok Srivastava
    Full-text Article · May 2016 · Journal of Radioanalytical and Nuclear Chemistry
  • Arjun Singh · Prateek Kishore · Manjit Singh · Alok Srivastava
    [Show abstract] [Hide abstract] ABSTRACT: The radiation effects on semicrystalline poly(vinylidene fluoride–chlorotrifluoroethylene) copolymer [poly(VDF–CTFE)] induced by proton beam irradiation were investigated. The poly(VDF–CTFE) films were exposed to 4 MeV protons at different fluence in the range of 2.7 × 1013 to 65.0 × 1013 protons/cm2. Changes in the chemical structural and thermal properties of pristine films as well as irradiated samples were studied using Fourier Transform Infrared (FTIR) and thermal analytical techniques, namely Thermogravimetric Analysis and Differential Scanning Calorimetry (DSC), respectively. FTIR spectroscopic data revealed two new bands at 1650 and 1747 cm−1 for irradiated samples whose intensities gradually increased with increasing ion fluence from 2.7 × 1013 to 27.0 × 1013 protons/cm2 due to the formation of carbon–carbon double bonds. The thermal stability was found to decrease after proton irradiation due to chain-scission. DSC data revealed that the proton irradiation was found to change in heat of fusion and crystallinity depending upon the applied dose.
    Article · Oct 2015 · Radiation Effects and Defects in Solids
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    [Show abstract] [Hide abstract] ABSTRACT: Harz Mts. region in the Germany states of Lower Saxony, Saxony-Anhalt and Thuringia is known for its heavy metal mines as well as smelting industry active since more than 3000 years. Trace elements like S, Cu, Zn, Sr, Pb, Br and Ti could be detected along with some normal elements, however U was not observed, although the Brocken granite contains 14 ppm U. The concentration of the elements which could be identified in the water samples was in general found to be within the permissible limits. It was further observed that there was an increase of two to ten times in the concentration of elements when the upstream data of Oker River was compared with that of its downstream from the Oker smelter complex.
    Full-text Conference Paper · Feb 2015
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    Alok Srivastava · Susanta Lahiri · Moumita Maiti · [...] · E. W. Schnug
    [Show abstract] [Hide abstract] ABSTRACT: The concentration levels of U-238, (232) Th, K-40 and Cs-137 in top soils of State of Punjab located in the North Western part of India were measured using conventional low background gamma ray spectrometric setup as well as Compton suppressed gamma ray spectrometric setup. The radioactivity level of U-238 and Th-232 was found to vary between 15 Bq/kg and 27 Bq/kg and between 16 Bq/kg and 57 Bq/kg respectively. The radioactivity level of K-40 was found to vary between 266 Bq/kg and 799 Bq/kg. The mean radioactivity level of the NORM in general was found to be similar to what is expected as a result of their normal abundance.
    Full-text Article · Nov 2014 · Journal of Radioanalytical and Nuclear Chemistry
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    Alok Srivastava · Friedhart Knolle · Frieder Hoyler · [...] · Ewald Schnug
    [Show abstract] [Hide abstract] ABSTRACT: Lately there has been an increasing concern about uranium toxicity in some districts of Punjab State located in the North Western part of India after the publication of a report (Blaurock-Busch et al. 2010) which showed that the concentration of uranium in hair and urine of children suffering from physical deformities, neurological and mental disorder from Malwa region (Fig. 1) of Punjab State was manifold higher than the reference ranges. A train which connects the affected region with the nearby city of Bikaner which has a Cancer Hospital has been nicknamed as Cancer Express due to the frenzy generated on account of uranium related toxicity.
    Full-text Chapter · Oct 2014
  • Alok Srivastava · K. K. Swain · B. Vashisht · [...] · A. V. R. Reddy
    Article · Apr 2014 · Journal of Radioanalytical and Nuclear Chemistry
  • Arjun Singh · Mahesh Kumar · Pramod Soni · [...] · Alok Srivastava
    [Show abstract] [Hide abstract] ABSTRACT: This paper describes formulation of plastic bonded explosives (PBXs) compositions based on 2,4,6- triamino- 1,3,5-trinitrobenzene (TATB), Octahydro l,3,5,7-tetranitro- 1,3,5,7-tetrazocine (HMX) by varying their relative amounts with Viton A as polymeric binder by slurry coating technique. These PBXs compositions are studied for mechanical and detonic properties. It has been observed that sensitivity and explosive performance of PBXs based on mixture of HMX and TATB were varied over a wide considerable range by varying relative amounts of TATB and HMX. The detonation study revealed there was increased in velocity of detonation (VOD) and detonation pressure with increasing amount of HMX from 10-80 % by weight. The sensitivity test results exhibited that insensitivity to impact for PBXs compositions was found to decrease with increasing HMX amount. Friction sensitivity study showed that no reactions were observed upto 36 kg load for PBXs compositions namely HT6030, HT5040, HT4050, HT3060, HT2070 and HT1080. The compressive strength of these PBXs compositions was found within the range of 9-11 MPa.
    Article · Dec 2013 · Defence science journal
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    Arjun Singh · P. K. Soni · T. Shekharam · Alok Srivastava
    [Show abstract] [Hide abstract] ABSTRACT: This article describes a study on thermal behavior of poly(vinylidene fluoride‐chlorotrifluoroetheylene) [poly(VDF‐CTFE)] copolymers as polymeric binders of specific interest for high energy materials (HEMs) composites by thermal analytical techniques. The non‐isothermal thermogravimetry (TG) for poly (VDF‐CTFE) copolymers was recorded in air and N2 atmospheres. The results of TG thermograms show that poly(VDF‐CTFE) copolymers get degrade at lower temperature when in air than in N2 atmosphere. In the derivative curve, there was single maximum degradation peak (T max) indicating one‐stage degradation of poly(VDF‐CTFE) copolymers for all the samples. The other thermal properties such as glass transition temperature (T g ) and degradation temperature (T d ) for poly(VDF‐CTFE) copolymers were measured by employing differential scanning calorimeter (DSC) technique. The kinetic parameters related to thermal degradation of poly(VDF‐CTFE) copolymers were investigated through non‐isothermal Kissinger kinetic method using DSC method. The activation energies for thermal degradation of poly(VDF‐CTFE) copolymers were found in a range of 218–278 kJ/mol. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
    Full-text Article · Feb 2013 · Journal of Applied Polymer Science
  • Arjun Singh · P.K. Soni · Manjit Singh · Alok Srivastava
    [Show abstract] [Hide abstract] ABSTRACT: In this paper, thermal degradation and degradation kinetic of a poly(vinylidene fluoride–chlorotrifluoroethylene) (poly(VDF–CFTE)) copolymers are investigated by thermogravimetry (TG) under non-isothermal conditions. Thermal degradation of poly(VDF–CFTE) copolymers namely FKM1, FKM2, FKM3 and FMK4 samples is carried out at different heating rate under nitrogen atmosphere. The activation energies of poly(VDF–CFTE) samples are calculated from Kissinger–Akahira–Sunose (KAS) and Friedman kinetic methods. To investigate the kinetic model of thermal degradation for poly(VDF–CTFE) copolymers, Criado method is employed. The results showed that the probable model for the degradation of poly(VDF–CTFE) copolymers agreed with a power law and diffusion (D1) model. The activation energies of FKM1, FKM2, FKM3 and FKM4 samples are found to be 196, 197, 198 and 207 kJ mol−1, respectively.
    Article · Nov 2012 · Thermochimica Acta
  • Munendra Singh · Alok Srivastava · Amol D. Shinde · [...] · I. B. Singh
    [Show abstract] [Hide abstract] ABSTRACT: In northern part of Indian sub-continent, As related environmental and health issues receive attention from all over the world. Forty-eight sediment samples were collected from the Ganga Alluvial Plain (GAP) and its weathering products (from the Gomati River) for the study of As distribution and mobilization. These sediment samples were analyzed by Instrumental Neutron Activation Analysis (INAA) method using Cirus Research Reacter of Bhabha Atomic Research Centre, Mumbai. Average As concentrations in the GAP sediments (10.44 mg kg−1), the Gomati River bed sediments (1.36 mg kg−1) and the Gomati River suspended sediments (5.30 mg kg−1) were reported. Significant decrease of As content from the alluvial sediments to the river sediments is a clear indication of its mobilization by chemical weathering processes of mineral biotite. Present study demonstrates the importance of INAA for quantification and mobilization of As and improves our understanding related to As related environmental issues in northern India and elsewhere.
    Article · Nov 2012 · Journal of Radioanalytical and Nuclear Chemistry
  • Prerna Aggarwal · Virendra Singh · Arjun Singh · [...] · Alok Srivastava
    [Show abstract] [Hide abstract] ABSTRACT: Thin films of poly(ethyleneterephthalate) (PET) were exposed to different radiation dose brought about by 80 MeV carbon and 98 MeV silicon ion beam. The UV–vis absorption studies reveal that there is decrease in optical band gap energy to the extent of ∼29.3 and 42.1%. The X-ray diffraction analyses have shown that crystallite size decreased by ∼18.6 and 52.6%, indicating amorphization of PET. The colour of PET films change from colourless to light yellowish followed by light brown as radiation dose is increased. The colour formation has been ascribed to an increase in conjugation in the carbon chain. In the case of PET irradiated with carbon ion, the electrical conductivity increased with frequency beyond a threshold value of 1 kHz. The increase in conductivity of PET films on irradiation is due to formation of defects and carbon clusters as a result of polymer chain scission. The thermal study further confirmed the increase in amorphous nature with increase in radiation dose. The results indicate that radiation dose brings about significant physicochemical transformations in PET.
    Article · Mar 2012 · Radiation Physics and Chemistry
  • Alok Srivastava · K. K. Swain · Nicy Ajith · [...] · Uttam Mete
    [Show abstract] [Hide abstract] ABSTRACT: Kidney stones obtained from six patients belonging to the stone belt region of India (Punjab) were analyzed for inorganic constituents using instrumental neutron activation analysis (INAA) and energy dispersive X-ray fluorescence (EDXRF) techniques. For INAA, samples were irradiated along with IAEA RM Soil 7 as reference standard in CIRUS reactor, BARC, Mumbai. Gamma activity of irradiated samples was measured using a 45% relative efficiency HPGe detector coupled to 8 k channel analyzer. EDXRF method was used for determination of concentration of Ca. The concentrations of ten elements namely Ca, Na, K, Mn, Co, Cr, Zn, Br, Sm and Cl, are reported and discussed.
    Article · Dec 2011 · Journal of Radioanalytical and Nuclear Chemistry
  • Alok Srivastava · D. Pathania · K. K. Swain · [...] · H. Nayyar
    [Show abstract] [Hide abstract] ABSTRACT: The phyto-accumulation efficacy of selenium (Se) from soil by chickpea plant is reported. Chickpea plants were grown in soil having different concentrations (1–4 mg kg−1) of Se. Samples of soil and different parts of chickpea plants in Se rich soil were analyzed for determination of Se concentrations by instrumental neutron activation analysis (INAA). Samples were irradiated in self-serve facility of CIRUS reactor, BARC, Mumbai at a neutron flux of the order of 1013 cm−2 s−1. The gamma activity at 264.7 keV of 75Se (119.8 d) was measured using a 45% relative efficiency HPGe detector coupled to MCA. Dependence of Se distribution in soil and plants on its spiking concentration was evaluated in this work. The Se concentrations determined in plant parts grown in control soil and in soil spiked with Se (4 mg kg−1) are in the range of 0.6–0.8 and 65–68 mg kg−1 respectively.
    Article · Nov 2011 · Journal of Radioanalytical and Nuclear Chemistry
  • Sajeela Awasthi · Alok Srivastava · M.L. Singla
    [Show abstract] [Hide abstract] ABSTRACT: Cyclic voltammetry was used to investigate the electrochemical behavior of citric acid (CA) and quinine hydrochloride (QH) at a polypyrrole-pentacyanoferrate/Platinum (PPY–PCNFe/Pt) electrode in aqueous medium. The analytical plots obtained were found to be linear in the concentration range between 1.0 and 9.0mM for both the analyte solutions. The detection limits (3δ) were found to be 1.17×10−4M and 1.08×10−5M for CA and QH analyte solutions, respectively. It was further observed that the diffusion of ionic species into and out of the polymeric film made the PPY–PCNFe/Pt electrode highly electroactive thereby enabling it to efficiently detect the analyte solutions having concentration as low as 1mM.
    Article · Aug 2011 · Synthetic Metals
  • Alok Srivastava · G S Bains · R Acharya · A V R Reddy
    [Show abstract] [Hide abstract] ABSTRACT: Soil samples from the seleniferous region of Punjab State in India were analyzed by instrumental neutron activation analysis (INAA) using reactor neutrons and high resolution γ-ray spectrometry. Samples were collected from three different depths namely surface, root and geological bed zones. Concentrations of 15 elements including selenium and arsenic were determined by relative method. For comparison purposes, soil samples collected from a non-seleniferous region were also analyzed.
    Article · Feb 2011 · Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine
  • Virendra Singh · Manindar Kaur · Tejvir Singh · [...] · Alok Srivastava
    [Show abstract] [Hide abstract] ABSTRACT: A polyaniline based conducting composite was prepared by oxidative polymerisation of aniline in presence of polyvinylchloride (PVC) matrix. The coherent free standing thin films of the composite were prepared by solution casting method. The PVC-polyaniline composite (90:10) of thickness 40 μm was irradiated with 90 MeV C5+ ions at different ion fluence ranging 5× 1011-5× 1013 ions/cm2. The changes in resistance of pristine and irradiated composite in presence of ammonia gas were studied. A general decrease in surface resistance is observed upon irradiation. The sensitivity, response time and recovery time were studied as a function of ion fluence on exposing the sensor material to ammonia gas at ambient condition. It is observed that irradiated composite films are more sensitive and fast in response to ammonia gas. The preliminary results observed are encouraging.
    Article · Jan 2011 · MRS Online Proceeding Library Archive
  • [Show abstract] [Hide abstract] ABSTRACT: The mungbean plants were grown hydroponically in the absence (control) or presence of 0.1, 0.25, 0.50 and 0.75 ppm selenium (as sodium selenate) for 10 days. The growth of shoots and roots increased with application of selenium with greater extent in shoots. With 0.5 and 0.75 ppm Se levels, the shoot growth was stimulated by 24% to 27% over control, respectively, while the roots showed a corresponding increase of 18-19%, respectively. The shoot-to-root ratio was enhanced significantly with Se application and maximum effects occurred at 0.75 ppm Se. A significant increase was observed in chlorophyll and cellular respiration ability with 0.5 and 0.75 ppm selenium. The increase in growth by selenium was accompanied by elevation of starch, sucrose and reducing sugars. The activity of starch hydrolysing enzymes--amylases and sucrose hydrolysing enzyme--invertase was stimulated significantly with selenium. This was associated with elevation of activities of sucrose synthesising enzymes--sucrose synthase and sucrose phosphate synthase. It was concluded that increase in growth of shoots and roots by application of Se was possibly the result of up-regulation of enzymes of carbohydrate metabolism thus providing energy substrates for enhanced growth.
    Article · Oct 2010 · Biological trace element research
  • Sajeela Awasthi · Alok Srivastava · M. L. Singla
    [Show abstract] [Hide abstract] ABSTRACT: With a view to develop conducting polymer film of high electroactivity, pentacyanonitrosylferrate (PCNFe) doped polypyrrole (PPY) composite films are prepared using cyclic voltammetry deposition method. The PPY–PCNFe composite is characterized by FTIR, TEM and TGA analysis. The electroactivity of PPY–PCNFe composite film is studied in 3 mM KCl (common electrolyte) solution. Two redox pairs at E1/2 = −0.59 V and 0.02 V due to redox behavior of polymer and dopant anions respectively are observed. The electroactivity study reveals the existence of two types of PCNFe dopant anions in the polymeric film: one form is loosely held and prone to easy removal from the polymer matrix whereas the other form is strongly bound to polymer backbone and prone to electrochemical redox reaction by movements of electrons. The high electroactivity of the film is attributed to the movements of ionic species into and out of the polymeric film as well as movements of electron.
    Article · Jul 2010 · Synthetic Metals