A L Verma - Academia.edu (original) (raw)

Papers by A L Verma

Indian Journal of Pure & Applied Physics, 1999

A composite polymer electrolyte based on polyethylene oxide (PEO): NaI system dispersed with sodi... more A composite polymer electrolyte based on polyethylene oxide (PEO): NaI system dispersed with sodium metasilicate (Na2Si03) has been reported. The structural, thermal and electrical behaviour of the materials have been characterised using optical microscopy, X-ray diffraction, differential scanning calorimetry and impedance spectroscopy . A maximum electrical conductivity of 10--<> S.cmat 4 5°C and 1.2 x 10-3 S.cm -I at 100°C has been achieved with the dispersion of the adduct, Na2SiOJ' The temperature dependence of the conductivity follows an Arrhenius type plots before and after the melting temperature {TJ1l} of PEO in the composite materials.

Chemical Physics Letters, 1997

Pump/probe time-resolved resonance Raman experiments (TR 3) on free-base tetraphenylporphyrin (H2... more Pump/probe time-resolved resonance Raman experiments (TR 3) on free-base tetraphenylporphyrin (H2TPP) in benzene and benzene plus CCI~ mixed solvents were carried out to probe the mechanistic details and transient species involved in the photooxidation of H2TPP. We have detected spectral features due to the w-radical cation, and exciplex transient species in the singlet and triplet excited states at different timescales in the presence of CCI a under laser irradiation. A mechanism for the photooxidation of porphyrins is discussed.

Journal of Physics and Chemistry of Solids, 1994

... Chem. Solids 28, 405 (1967). 7. Huong PV and Hilczer B., J. Chem. Phys. 72, 4412 (1980). 8. L... more ... Chem. Solids 28, 405 (1967). 7. Huong PV and Hilczer B., J. Chem. Phys. 72, 4412 (1980). 8. Lock PJ, Phys. Lett. (USA) 19, 390 (1971). 9. Galanov EK, Opt. Speclr. 24, 137 (1968). 10. Kislovski LD, Galanav EK and Shuvalov LA, Opt. Spectr. 24, 102 (1978). 11. ...

University of Wisconsin Whitewater Library, Oct 11, 2009

Gastroenterología y Hepatología, 2022

Colorectal cancer 5-years-survival is 57%, partway due to a low rate of participation in screenin... more Colorectal cancer 5-years-survival is 57%, partway due to a low rate of participation in screening programmes. Instruments analyzing causes of low adherence are needed. To evaluate the validity and internal consistency of the Spanish version of Rawl's Questionnaire for the screening of colorectal cancer by faecal occult blood testing. Questionnaire validation methodology. Three Primary Care Centres in Valencia. Age, sex, civil status, educational level, social class, smoking, alcohol consumption, Body Mass Index, personal and family history of cancer. We analyzed 408 individuals (237 cases and 171 controls). Mean age was 59.45 years (SD 5.17). Internal consistency of all variables reached a Cronbach's alfa of 0.796. The Cronbach's alfa benefit dimension of the screening was 0.871 and for the barrier dimension of the screening it was 0.817. Intraclass correlation coefficients of the test-retest for the benefit dimension of the screening was 0.809 (CI 95% 0.606-0.913) and 0.499 (CI 95% 0.126-0.750) for the barrier dimension. The Spanish version of Rawl's Questionnaire is valid, reliable and reproducible, so we have this validated instrument with which to identify barriers and benefits in a colorectal screening programme in Spain.

Jurnal Aktual Justice, 2021

Decentralization is one of the political choices in order to ensure the implementation of governm... more Decentralization is one of the political choices in order to ensure the implementation of government affairs in the regions. History has noted that Indonesia has attempted (still) an ideal formula in the administration of local government, starting from the implementation of symmetrical or asymmetrical decentralization. This is not an easy matter considering the diversity that exists in each region, so a special method is needed to be able to fulfill the wishes of each region proportionally. The decentralization that Indonesia needs does not seem to be just ordinary decentralization, empirically Indonesia has actually implemented what is called asymmetric decentralization or decentralization that is not the same/not uniform for each region. The Papua region is an example of the implementation of asymmetric decentralization, but the problem is that the special labeling of the region reflects an asymmetrical framework, namely a serious effort designed to accommodate regional needs by ...

National Academy Science Letters, 2018

AbstractThe vanadyl doped K1.98 (NH4)0.02(C2O4)2.H2O system is studied at room temperature using ... more AbstractThe vanadyl doped K1.98 (NH4)0.02(C2O4)2.H2O system is studied at room temperature using Electron Paramagnetic Resonance (EPR) technique. Two distinct interstitial sites for vanadyl ion are found in the potassium oxalate monohydrate crystal grown with 1% ammonium oxalate monohydrate salt. This is confirmed from angular variation of EPR spectra with static magnetic field H in the ac crystal plane. The ammonium ions seem to act as catalyst for vanadyl ions to occupy otherwise more difficult two interstitial sites in the mixed system. The formation of VO [(C2O4)4.H2O] complex is envisaged in our system and relevant ‘g’ and ‘A’ parameters are obtained through EPR studies.

Spectrochimica Acta Part A: Molecular Spectroscopy, 1971

Abstract The i.r. spectra of diethyl amine have been investigated over the frequency range 4000–2... more Abstract The i.r. spectra of diethyl amine have been investigated over the frequency range 4000–250 cm−1 in the vapour, liquid, and solid phases and as solution in various solvents. The Raman spectrum of the liquid has been recorded photoelectrically and depolarization measurements have been made. The temperature dependence of some of the i.r. bands indicate the presence of at least two rotational isomers (trans-trans and trans-gauche) in fluid phase, whereas in the solid phase at low temperature, the molecule assumes the “trans-gauche” conformation having no symmetry. A vibrational assignment for the observed bands has been proposed, keeping in view the presence of rotational isomers in vapour and liquid phases.

Physical Review B, 1993

Stage-1 iodine-intercalated IBi 2 Sr 2 CaCu 2 O 8 single crystals with T c= 78 K were studied by ... more Stage-1 iodine-intercalated IBi 2 Sr 2 CaCu 2 O 8 single crystals with T c= 78 K were studied by Raman microspectroscopy in comparison with undoped Bi 2 Sr 2 CaCu 2 O 8. Evidence is shown for the existence of an asymmetrical I 3-state and a weak interaction is revealed ...

Thin Solid Films, 2011

We have developed a process for preparation of composites by blending and ultrasonification of mu... more We have developed a process for preparation of composites by blending and ultrasonification of multi-walled carbon nanotubes with metal-phthalocyanines and have used the same as very selective and sensitive sensor for detection of H 2 O 2 vapors. A combination of sensors made from composites of cobalt-phthalocyanine and copper-phthalocyanine with multiwall carbon nanotubes has been found to show opposite conductivities to H 2 O 2 vapors while the pair shows similar response to other chemical vapors. This unusual behavior makes this paired sensor as a reliable method to selectively identify the presence of H 2 O 2 vapors with response and recovery times of few seconds. Our developed sensors work at room temperature and show resistivity in the range of 10 4 to 10 5 Ω cm. They can be employed for detection of H 2 O 2 based explosives, to monitor levels of H 2 O 2 in industrial units and other applications.

Polymer Engineering & Science, 2013

Polymer nanocomposites (NCs) are a special class of materials having unique properties and wide a... more Polymer nanocomposites (NCs) are a special class of materials having unique properties and wide application potential in electronics and other diverse areas. In this study, NCs consisting of poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonate) (PEDOT:PSS) matrix reinforced with graphite nanosheets were fabricated by solution method. The graphite used was functionalized before fabrication of NCs. The functionalized graphite was characterized by transmission electron microscopy (TEM) and Fourier transform Infrared spectroscopy (FTIR) technique. The NCs prepared were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and FTIR technique. The conductivity studies of the prepared NCs were carried out. The prepared NCs films were investigated for the detection of nitrobenzene vapors. The detection mechanism is based on measuring resistivity changes that occur in a NC due to the absorption of nitrobenzene vapors by PEDOT:PSS film. These sensors exhibited excellent response at room temperature when exposed to vapors of nitrobenzene. Sensitivity as high as 18.5% was observed for PEDOT:PSS/NGPs composite. The chemresistor exhibits a fast response ($1.14 min) and good recovery time ($1-2 min). The response of NC to the nitrobenzene vapors is reproducible.

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Journal of Molecular Spectroscopy, 1971

Dimethoxymethane CH30CH,0CH3 is one of the most fundamental ether molecules and its vibrational s... more Dimethoxymethane CH30CH,0CH3 is one of the most fundamental ether molecules and its vibrational spectra have been investigated in detail [l-3]. The previous studies showed the presence of only the gauche-gauche form in any state of aggregation. Recent systematic studies on the vibrational spectra of alkyl ethers [4, 51, among which dimethoxymethane was not in-cIuded, prompted us to reexamine more closely the rotational isomerism of this molecule_ In the present study, therefore, the Raman and IR spectra of dimethoxymethane in various states of aggregation were analysed and rotational isomers existing in each state were determined on the basis of the calculation of normal coordinates. Since a dimethoxymethane molecule has two internalrotation axes associated with the rotational isomerism, there are four possible rotational isomers, i.e., gauche-gauche (GG), trans-gauche (TG), transtram (TT) and gaucheqauche' (GG').

CHINESE …, 1993

Page 1. . t Refereed version of the contributed paper presented at the International Conference o... more Page 1. . t Refereed version of the contributed paper presented at the International Conference on Super-conductors, August 27-30, 1993, Sun Moon Lake, Nan-tou, Taiwan, ROC 1151 @ 1993 THE PHYSICAL SOCIETY OF THE REPUBLIC OF CH1N.A ...

Journal of Physics and Chemistry of Solids, 1977

Crystal Research and Technology, 2002

Phase transition studies in mesogenic dimers Schiff base liquid crystal dimers, both symmetric an... more Phase transition studies in mesogenic dimers Schiff base liquid crystal dimers, both symmetric and non-symmetric, in which two anisotropic groups are linked by a flexible spacer, exhibit a rich variety of smectic mesomorphism. The interest in this class of mesogens stems not only from their ability to act as model compounds for semi-flexible mainchain liquid crystal polymers but also from their quite different properties compared to conventional low molar mass liquid crystals (monomers). We report here the phase transition studies on two examples of these schiff base liquid crystal dimers using the Differential Scanning Calorimetry and density measurements as a function of temperature. The symmetric liquid crystal dimer, α,ω-bis (4-ndodecylaniline benzylidene-4′-oxy)decane (10.O12O.10) exhibits a very rare Isotropic to G transition. Where as, the non-symmetric dimer, α-(4-cyano biphenyl-4′-yloxy)-ω-(4-n-decylanilinebenzylidene-4′-oxy)decane (CB.O10O.10) exhibits a rare nematic to intercalated smectic A phase transition. The transitions studied, isotropic to nematic and isotropic to G exhibit a large density jump at the transition confirming their first order nature. Nematic to intercalated smectic A transition is found to be a second order transition whose behavior is similar to nematic to smectic A transition. Calculated values of pressure dependence of transition temperature and thermal expansion coefficient are also reported.

Bulletin of Materials Science

We report Raman spectral studies of pure potassium oxalate monohydrate, K 2 C 2 O 4 • H 2 O (POM)... more We report Raman spectral studies of pure potassium oxalate monohydrate, K 2 C 2 O 4 • H 2 O (POM) and its doped varieties with 1 and 5% vanadyl concentrations at room temperature. Apart from many other interesting changes in the Raman spectra on doping with VO 2+ , one of the most intriguing observations is the change in relative intensities of factor group split components of several Raman bands including some bands in the lattice mode region. We have explained the relative intensity changes of factor group split components in terms of locking of adjacent C 2 O 4 −H 2 O−C 2 O 4 −H 2 O chains due to vanadyl doping in the POM lattice. The reduction in the intensities of water bands on vanadyl doping also supports this view.

Journal of Physics C: Solid State Physics

The temperature dependence of the halfwidth and centre frequency of the v3 fundamental and its co... more The temperature dependence of the halfwidth and centre frequency of the v3 fundamental and its combination with the low-frequency gap mode of t h e N O j ion doped in KI single crystal has been investigated from 1.7 to 77 K. From this study, detailed information about the variation of halfwidth and centre frequency of the gap mode as a function of temperature has been obtained which can be satisfactorily explained in terms of anharmonic interactions of the gap mode with lattice phonons.

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