Browsing by Author "Kamlesh Pandey"

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A rechargeable solid-state proton battery with an intercalating cathode and an anode containing a hydrogen-storage material
(Elsevier, 1998) Kamlesh Pandey; N. Lakshmi; S. Chandra
Rechargeable proton batteries have been fabricated with the configuration Zn + ZnSO4 · 7H2O/ /solid-state proton conductor/ /C + electrolyte + intercalating PbO2 + V2O5. The solid-state proton conductor is phosphotungstic acid (H3PW12O40 · nH2O) or a H3PW12O40 · nH2O + Al2(SO4)3 · 16H2O composite. The maximum cell voltage is ∼ 1.8 V at full charge. The cell can run for more than 300 h at low current drain (2.5 μA cm-2). Further, the cell can withstand 20 to 30 cycles. The addition of a metal hydride in the anode side enhances the rechargeability and the addition of a small amount of Al2(SO4)3 · 16H2O in the H3PW12O40 · nH2O electrolyte improves the performance of the battery. © 1998 Elsevier Science S.A. All rights reserved.
Assessment of topsoil contamination in an urbanized interfluve region of Indo-Gangetic Plains (IGP) using magnetic measurements and spectroscopic techniques
(Springer International Publishing, 2019) Abhishek Kumar Rai; Anuj Kumar Singh; Jayanta Kumar Pati; Shubham Gupta; Munmun Chakarvorty; Ambalika Niyogi; Anamika Pandey; Mrigank Mauli Dwivedi; Kamlesh Pandey; Kuldeep Prakash
The magnetic susceptibility (MS) measurements are used for rapid and cost-effective soil surveys and for accessing heavy metal contamination worldwide. In the sub-Himalayan plains of India, nearly 6.05 × 104 km2 area of most the fertile land occurs as interfluve of Late Quaternary age between the two major glacier-fed rivers (Ganga and Yamuna). The vast areal expanse of interfluve terminates at the rivers’ confluence in Sangam (25°25′13″N-81°53′22″E), Allahabad. This is the first study of MS soil survey of the interfluve region at the confluence comprising 490 samples from 49 locations. The MS values are between 8.84 and 261.25 × 10−8 m3 kg−1 and the change is more pronounced (8.84–312.65 × 10−8 m3 kg−1) with increasing depth. A sudden increase in the MS between 12- (11.28–303.32 × 10−8 m3 kg−1) and 14-cm (11.21–238.45 × 10−8 m3 kg−1) depth is observed similar to observations worldwide. The high MS hotspots are aligned parallel to major traffic networks of the city suggesting a major contribution emanating from the anthropogenic load. A significant difference has been noted in the MS values of present-day mid-channel bar sediments of Ganga (25.24 × 10−8 m3 kg−1) and Yamuna (116.47 × 10−8 m3 kg−1) Rivers. The laser-induced breakdown spectroscopy (LIBS) data showed the presence of heavy (Fe, Ti, Cr, Cu, Cd, Zn, and Pb) and light (H, C, N, and O) elements supporting MS data. The concentration of toxic elements predicted by partial least squares regression (PLSR) approach concurs with magnetic measurements. The topsoil MS values increase up to a depth of ~ 6.25 cm suggesting the dominant role of anthropogenic source for the increased heavy metal concentration compared with basement contributions. © 2019, Springer Nature Switzerland AG.
Diffusion-limited aggregation in potato starch and hydrogen borate electrolyte system
(2013) Tuhina Tiwari; Manindra Kumar; Kamlesh Pandey; Neelam Srivastava; P.C. Srivastava
Natural growth of diffusion-limited aggregate (DLA), without any external stimuli, in boric acid doped starch system is reported here. Fractals grown were confirmed to be of diffusion-limited aggregate (DLA) pattern having fractal dimension 1.49. Effect of substrate and humidity on growth pattern has also been discussed. The existence of a different vibration band of H3BO 3 in FTIR confirmed that growth structures are related to boric acid. XRD pattern has shown broad peak along with some sharp peaks. Broad peak is related to starch's amorphous nature, as where intense sharp peaks are due to boric acid. © 2013 Tuhina Tiwari et al.
Evidence of failure of hopping model of ionic conductivity in phosphomolybdic acid studied by a.c. conductivity measurements
(Kluwer Academic Publishers, 1999) Kamlesh Pandey; N. Lakshmi
The a.c. conductivity measurement has been used to probe into the possible conduction mechanisms (Vehicle or Hopping) in proton conducting acid hydrate Phosphomolybdic acid H3PO4·12MoO3·nH2O. The magnitude of hopping rate and its temperature dependence evaluated from a.c. conductivity data does not favour the hopping mechanism of conduction. The value of activation energy (Ea to approximately 0.76 eV) supports the vehicle mechanism of ion transport.
Experimental Synthesis of Coloured Soda-lime-silica (SLS) Glasses using Untreated Silica Sand of Shankargarh Area (Prayagraj District, Uttar Pradesh, India) and its Ramifications
(Springer, 2022) Anuj Kumar Singh; Pawan Kumar Rajak; Jayanta Kumar Pati; Mrigank Mauli Dwivedi; Kamlesh Pandey; Kuldeep Prakash; Abhishek Kumar Rai; Shivanshu Dwivedi
The physical, mechanical and chemical processing of silica sand, the main ingredient of silicate glass, are routinely carried out in glass and ceramic industries worldwide to enhance the silica content and to reduce the concentration of ferromagnesian impurities. The processing of silica sand prior to glass synthesis generally involves washing with water, physical screening (size and magnetic separation) and chemical treatments. The silica sand mining, in parts of Prayagraj (earlier known as Allahabad) district, Uttar Pradesh, is continuing for more than six decades and yet meager peer-reviewed published scientific data is available hitherto. On the other hand, the continued rampant water cleaning of silica sand for more than six decades has led to the accumulation of toxic sludge in the vicinity and also causing ground water depletion in the area. In order to find an amicable balance amongst silica sand processing, ground water depletion and environmental degradation, an attempt has been made to use untreated/raw silica sand of Prayagraj district, mainly from the Shankargarh area, to synthesize soda-lime-silica (SLS) glass. Following this objective, thirty five silica sand samples are collected from different washeries and grouped into seven classes based on their magnetic susceptibility values (30.23 to −0.71 × 10−8 m3kg−1). Representative silica sand samples from these seven groups are mixed with sodium carbonate (Na2CO3) and calcium carbonate (CaCO3) in a ratio of 75:15:10 and melted at 1300°C under one atmospheric pressure for a run duration of 90 minutes. Transparent to translucent SLS glasses of various hues and variable refractive indices (1.504–1.547) are formed. The glasses, thus analyzed by the electron probe micro analyzer (EPMA), comprise SiO2 (80.56–85.79 wt%), Na2O (9.70–12.69 wt%), CaO (4.80–6.51 wt%), Al2O3 (0.51–1.46 wt%), FeOT (0.15–0.95 wt%) and TiO2 (0.12–0.29 wt%), similar to the commercial SLS glasses manufactured worldwide. The present study suggests that the raw silica sand from Shankargarh area can be used to synthesize coloured SLS glasses even without washing with water and as a consequence the water resources and geo-environment of the area shall remain protected from further degradation. © 2022, Geological Society of India, Bengaluru, India.
Rapid Communication: Protonic Transport in Dehydrated Aluminium Sulphate
(1992) S.A. Hashmi; Kamlesh Pandey; S. Chandra
Dehydrated aluminium sulphate has been shown to possess H4 ion conductivity at high temperatures (~ 200-400 °C) as studied by a in air and hydrogen ambient and IB and electrochemical EMF measurements. This suggests that some dehydrated salts may be tried as a route for developing new proton conductors. © 1992 IOP Publishing Ltd.
Supercapacitor performance of polymer-in-salt electrolyte/water-in-polymer salt electrolyte synthesized by complexing glutaraldehyde crosslinked corn starch with Mg(ClO4)2
(Springer Science and Business Media Deutschland GmbH, 2024) Dipti Yadav; Kamlesh Pandey; Kanak Aggarwal; Neelam Srivastava
Energy devices with high energy/power density are the need of the day, and to achieve the same, electrolytes with faster ion transport and wider electrochemical stability window are required. Polymer-in-salt electrolytes (PISEs) are predicted to have the better required electrochemical properties in comparison to salt-in-polymer electrolytes (SIPEs), but desired success is still to be achieved due to recrystallization problems. PISEs suffer from poor mechanical and/or electrochemical properties along with aging effects as well; hence, special efforts are required to reduce the crystallinity of PISEs. The present paper discusses a crosslinked corn starch complexed with Mg(ClO4)2 which not only has desired electrochemical properties but is also flexible. XRD study confirms the absence of crystalline nature, without any extra efforts to reduce it. Synthesized PISEs have high conductivity (~0.01 Scm−1), wide ESW (> 3 V), and low relaxation time (µs) along with being economical. Supercapacitors fabricated using this novel PISE with laboratory synthesized activated carbon (from leaves and corn starch) have shown good specific capacitance (~ 20 Fg−1 and ~ 45 Fg−1, respectively). The power density is of the order of kW kg−1, which is quite high in comparison to other reports. The shape of CV and LSV is strongly influenced by the salt concentration, i.e., by the ion-cluster size, and is also affected by the volume/size of the activated carbon pores. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.
Transport and thermal behaviour of composite : xH3PMo12O40.nH2O + (1-x)Al2O3
(1999) Kamlesh Pandey; N. Lakshmi; S. Chandra
Proton conducting composite electrolyte consisting of hydrated phosphomolybdic acid and Al2O3 has been prepared. Composition dependence of conductivity has been explained on the basis of the interface created by the adsorption of water derived from the hydrated acids onto the Al2O3 particulates. Evidence of such bonding has been obtained from the resulting changes in DTA/TGA and IR spectra of the composite electrolyte.