008381   Radhakrishnan S R (Physics Dep, Avinashilingam Women Univ, Coimbatore-43, Email: rugminiradhakrishnan@yahoo.com) : Design, development and study of a demonstration model solar updraft tower - a novel approach for generating electricity from solar thermal convective acceleration. Ultra Scient phys Sci 2009, 21(2), 419-24.

The solar updraft tower is a renewable energy device which uses solar thermal energy to provide upward convective acceleration to the inflow air by greenhouse effect. The hot air rising through the chimney stack drives the turbine and the rotational energy of the turbine is converted into electricity by a generator. The paper presents the design details and performance analysis of a self designed simple and compact demonstration model solar updraft tower made with locally available materials. The model is constructed with the prime aim of understanding chimney concept in experimental studies. Tests were conducted to evaluate the performance of the device by measuring the test parameters updraft velocity, temperature profiles of various junctions and power output. The results obtained indicate that the updraft velocity and power output depend on solar insolation and the height of the chimney stack with a constant collector area.

2 illus, 2 tables, 5 ref

008380   Pavuna D;Ariosa D;Cloetta D;Cancellieri C; Abrecht M (Institute of Physics of Complex Matter, FSB, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland, Email: davor.pavuna@epfl.ch) : Direct angle resolved photoemission spectroscopy and superconductivity of strained high-T_c films. Pramana J Phys 2008, 70(2), 237-43.

Since 1997 we systematically perform direct angle resolved photoemission spcdroscopy (ARPES) on in-situ grown thin (<60>30 nm) cuprate films. Specifically, we probe low-energy electronic structure and properties of high-T_c superconductors (HTSC) under different degrees of epitaxial (compressive vs. tensile) strain. In overdoped and underdoped in-plane compressed (the strain is induced by the choice of substrate) ≈15 nm thin La₂-_xSr_xCuO₄ (LSCO) films we almost double T_c to 40 K, from 20 K and 24 K, respectively. Yet the Fermi surface (FS) remains essentially two-dimensional. In contrast, ARPES data under tensile strain exhibit the dispersion that is three-dimensional, yet T_c drastically decreases. It seems that the in-plane compressive strain tends to push the apical oxygen far away from the CuO₂ plane, enhances the two-dimensional character of the dispersion and increases T_c, while the tensile strain acts in the opposite direction and the resulting dispersion is three-dimensional. Established the shape of the FS for both cases, and all our data are consistent with other ongoing studies, like EXAFS. As the actual lattice of cuprates is like a 'Napoleon-cake', i.e. rigid CuO₂ planes alternating with softer 'reservoir', that distort differently under strain, our data rule out all oversimplified two-dimensional (rigid lattice) mean field models. The work is still in progress on optimized La-doped Bi-2201 films with enhanced T_c.

2 illus, 1 table, 16 ref

008379   Paul J;Nishimatsu T;Kawazoe Y;Waghmare U V (Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560 064, Email: waghmare@jncasr.ac.in) : First-principles study of phase transitions in ultrathin films of BaTio₃. Pramana J Phys 2008, 70(2), 263-70.

Determines the effects of film thickness, epitaxial strain and the nature of electrodes on ferroelectric phase transitions in ultrathin films of BaTiO₃ using a first-principles effective Hamiltonian in classical molecular dynamics simulations. Presents results for polarization and dielectric properties as a function of temperature and epitaxial strain, leading to size-dependent temperature-strain phase diagram for the films sandwiched between 'perfect' electrodes. In the presence of non-vanishing depolarization fields when non-ideal electrodes are used, we show that a stable stripe-domain phase is obtained at low temperatures. The electrostatic images in the presence of electrodes and their interaction with local dipoles in the film explain these observed phenomena.

5 illus, 15 ref

008378   Pandey S K;Bindu R;Ashwani Kumar;Khalid S; Pimpale A V (NO, UGC-DAE Consortium for Scientific Research, Univ Campus, Khandwa Road, Indore-452 017, Email: ash_kmr2000@yahoo.com) : Doping and bond length contributions to Mn K-edge shift in La₁-_xSr_xMnO₃(x=0-0.7) and their correlation with electrical transport properties. Pramana J Phys 2008, 70(2), 359-66.

Room temperature experimental Mn K-edge X-ray absorption spectra of La₁-_xSr_xMnO₃ (x = 0-0.7) are compared with the band structure calculations using spin polarized density functional theory. It is explicitly shown that the observed shift in the energy of Mn K-edge on substitution of divalent Sr on trivalent La sites corresponds to the shift in the center of gravity of the unoccupied Mn 4p-band contributing to the Mn K-absorption edge region. This correspondence is then used to separate the doping and size contributions to the edge shift due to variation in the number of electrons in valence band and Mn-O bond lengths, respectively, when Sr is doped into LaMnO₃. Such separation is helpful to find the localization behaviour of charge carriers and to understand the observed transport properties of these compounds.

3 illus, 23 ref

008377   Nath G;Paikaray R (Engg Physics Dep, Dhaneswar Rath Institute of Engg. and Management Studies (DRIEMS), Tangi, Cuttack-754 022, Email: ganesh_nath99@yahoo.co.in) : Frequency dependent studies of acoustic parameters in binary mixture of non-polar and polar liquid. Ultra Scient phys Sci 2009, 21(2), 333-8.

The binary mixture of di-isopropylether (DIPE) and toluene has been studied extensively from the view point of their acoustic behaviour at different frequencies (1MHz, 3MHz and 5MHz) and constant temperature 303 K. Experimental values of ultrasonic velocity and density are used to compute the derived parameters. Further, these values are used for the calculation of excess parameters, since excess parameters are a better measure of intermolecular interactions than the derived ones. The variations of these excess parameter with frequencies are useful in several industrial and technological processes.

7 illus, 13 ref

008376   Mukesh Kumar (NO, , Diwakar Bhawan Mishra Tola, Gannipur, Muzaffapyr-842 001, Email: mukbihar@rediffmail.com) : Millimeter wave propagation through the layers of dielectric bodies. Ultra Scient phys Sci 2009, 21(2), 327-32.

Deals with the propagation of millimeter wave through the layers of dielectric bodies. Theoretical investigation has been carried out to estimate the absorption loss (P_abs) in which the wave guide has been utilized. For simplicity of the problem each layers of the dielectric body has been considered as a wave guide and entire layers equated as a number of transmission lines in cascade. Consequently the equation for reflection coefficient and transmission coefficient has been developed. It will be further utilized for the evaluation of absorption loss as function of frequency and the particle density. The result has good agreement with theoretical value.

4 illus, 5 ref

008375   Mookerjee A;Tarafder K;Chakrabarti A;Saha K K (Physics Dep, Indian Institute of Technology, Kanpur-208 016, Email: abhijit@bose.res.in) : Short-range order and its effect on the electronic structure of binary alloys: CuZn-a case study. Pramana J Phys 2008, 70(2), 221-35.

Discuss an application of the generalized augmented space method introduced by one of us combined with the recursion method of Haydock et al (GASH) to the study of electronic structure and optical properties of random binary alloys. As an example, we have taken the 50-50 CuZn alloy, where neutron scattering indicates the existence of short-range order.

5 illus, 56 ref

008374   Mohan R;Bharti M;Kaur M;Ganapathi K;Gupta S K (Physics Dep, Barkatullah Univ, Bhopal) : Study of gas sensing properties of ZnO nanowire sensor. BARC Newsl 2009, 309(Oct; spl), 319-23.

Authors have studied the gas sensing properties of thick films prepared using ZnO nanowires. For this purpose, a paste of nanowires was prepared in methanol, painted on Alumina substrate followed by annealing at 500°C. ZnO nanowires were prepared by carbothermal method and characterized by SEM, EDX and XRD. The performance of films as a chemical sensor was studied, as a function of temperature for several toxic gases such as H₂S, NH₃, NO, CO and CH₄. These films were found to be highly sensitive to H₂S and NO gases. It was observed, that at room temperature, the film is more sensitive to H₂S gas as compared to NO gas, but recovery after exposure to NO gas is faster. With increase in temperature, there is not much change in recovery time after NO gas exposure, but on exposure to H₂S gas, recovery time decreases appreciably with increasing temperature.

6 illus, 8 ref

008373   Manoj Kumar (NO, B.R.A. Bihar Univ, Muzaffarpur, Bihar, Email: manojkr_phys@yahoo.com) : Theory for transport properties of semiclassical fluids. Ultra Scient phys Sci 2009, 21(2), 345-50.

The effective diameter hard sphere theory is employed to estimate the transport properties (TP's) of semiclassical fluids. The TP's of the fluids are expressed in terms of a classical hard sphere (HS) fluid of properly chosen hard sphere diameter. The explicit expressions for the shear viscosity and thermal conductivity for the HS fluid are given. The theory is applied to estimate the TP's of fluids Ar and Ne. The agreement is found to be fairly good.

1 illus, 2 tables, 11 ref

008372   Manna S;Chowdhury S;Satpati S K;Roy S B (Uranium Extraction Div, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : Prediction of firing time of magnesio thermic reduction (MTR) reaction and study of relative importance of the dependent parameters using artificial neural network. BARC Newsl 2009, 309(Oct; spl), 222-32.

In uranium metal production process, uranium ingot is generally produced by Magnesio Thermic Reduction (MTR) of uranium tetra fluoride. This highly exothermic reaction is carried out in a closed vessel, called 'bomb reactor', lined with MgF₂. Initiation of this instantaneous reaction is indicated by sudden temperature shoot up of the reaction mixture and it is called firing. It is observed that the time required to initiate the reaction (firing time), depends on various parameters of the reactants and the lining material along with operating parameters. But no correlation is available to correlate the firing time as a function of all these parameters together. Artificial neural network is used here to predict firing time, based on these parameters using BIKAS software and exclusive studies were carried out here, to study the relative importance of the parameters on firing time.

4 illus, 3 tables, 11 ref

008371   Mahto S B;Mahto J P;Pandit S R (Physics Dep, S.K.M. Univ, Dumka (Santhal Pragana), Jharkand) : Evaluation of thermoelectric power oscillation in the vicinity of electronic topological transition (ETT). Ultra Scient phys Sci 2009, 21(2), 387-94.

Using the theoretical model developed by Ya. M. Blanter et. al. (Nuovo Cemento 12, 1900 (1990) and taking into account the possibility of Fermi surface topology transformations in the presence of magnetic field, the expression in different regions of ETT vicinity has ben obtained. On analysing in weak and strong magnetic field, Our analysis shows field dependence of the thermoelectric coefficient. The peaks weak linearly increases with increasing of the magnetic field.

21 ref

008370   Mahto S B;Mahto J P;Pandit S R (Physics Dep, S.K.M. Univ, Dumka (Santhal Pragana), Jharkhand) : Electron relaxation time in the vicinity of electronic topological transition (ETT) in the presence of magnetic field. Ultra Scient phys Sci 2009, 21(2), 301-6.

Kinetic phenomena in the vicinity of electronic topological transition predicted by Lifshitz have been widely studied both theoretically and experimentally. Using one electron Green's function in the framework of temperature diagrammatic technique developed by Ya. M. Blantr et. al. Nuovo Cimento vol. 12, 1900(1990), we have studied the relaxation time τ(<67>, Δ) for. EET transition. The result shows that there is an influence of magnetic field of EET relaxation time τ(<67>, Δ, Ω).

17 ref

008369   Mahto S B;Mahto J P;Pandit S R (Physics Dep, S.K.M. Univ, Dumka (Santhal Pragana), Jharkhand) : Giant oscillations of thermoelectric power of the normal metal in the presence fo magnetic field using electronic topological transition (ETT). Ultra Scient phys Sci 2009, 21(2), 279-84.

Using the theoretical model developed by Ya. M. Blanter et. al. (Nuovo Cemento 12,1900 (1900). Studied the giant oscillations of thermoelectric power of the normal metal in the presence of magnetic field. This is achieved because of electronic topological transition (EET). Our theoretically evaluated result indicates the anharmonical behaviour of the thermoelectric power in the region 2π^{2/Ω ≤ ∀.}

1 illus, 18 ref

008368   Mackinnon A (Blackett Laboratory, Imperial College London, South Kensington Campus, London SW7 2AZ, UK, Email: a.mackinnon@imperial.ac.uk) : Localization in disordered systems with interactions. Pramana J Phys 2008, 70(2), 211-20.

Present an improved numerical approach to the study of disorder and interactions in quasi-1D systems which combines aspects of the transfer matrix method and the density matrix renormalization group which have been successfully applied to disorder and interacting problems respectively. The method is applied to spinless fermions in 1D and a generalization to finite cross-sections is outlined.

6 illus, 23 ref

008367   Laik A;Bhanumurthy K (Materials Science Div, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : Diffusion in CU(AL) solid solution. BARC Newsl 2009, 309(Oct; spl), 115-20.

The solid state diffusion characteristics in the Cu(AI) solid solution phase, was investigated in the temperature range of 1023-1223 K, using single phase bulk diffusion couples, between pure Cu and Cu- 10 at.% Al. The interdiffusion coefficients, D, were calculated using Boltzmann-Matano method and HalI 's method from the concentration profiles of the couples acquired using EPMA. The calculated interdiffusion coefficients (D) ranged between 1.39 X 10^-14 and 3.97 X 10^-13 m²/s in the temperature range of 1023 to 1223 K. the composition and temperature dependence of D were established. The activation energy for interdiffusion varies from 123.1 to 134.2 kJ/mol in the concentration range 1 at.%≤ C_Al ≤ 9 at.%. The impurity diffusion coefficient of Al in Cu, is determined by extrapolating the interdiffusion coeffficient values, to infinite dilution of the alloy i.e. C_Al → 0 and its temperature dependence was also established. The activation energy for impurity diffusion of Al in Cu was found to be 137.1 kJ/mol.

4 illus, 4 tables, 15 ref

008366   Kamra A K;Pathak P;Singh V A (Electrical Engineering Dep, Indian Institute of Technology, Kanpur-208 016, Email: vsingh@hbcse.tifr.res.in) : Mean field approach to Coulomb blockade for disordered assembly of quantum dots. Pramana J Phys 2008, 70(2), 279-84.

Coulomb blockade (CB) in quantum dots (QDs) is by now well documented. It has been used to guide the fabrication of single electron transistors. Even the most sophisticated techniques for synthesizing QDs (e.g. MOCVD/MBE) result in an assembly in which a certain amount of disorder is inevitable. On the other hand, theoretical approaches to CB limit themselves to an analysis of a single QD. In the present work we consider two types of disorders: (i) size disorder; e.g. QDs have a distribution of sizes which could be unimodal or bimodal in nature, (ii) Potential disorder with the confining potential assuming a variety of shapes depending on growth condition and external fields. Assume a Gaussian distribution in disorder in both size and potential and employ a simplified mean field theory. To do this we rely on the scaling laws for the CB (also termed as Hubbard U) obtained for an isolated QD [1]. We analyze the distribution in the Hubbard U as a consequence of disorder and observe that Coulomb blockade is partially suppressed by the disorder. Further, the distribution in U is a skewed Gaussian with enhanced broadening.

3 illus, 9 ref

008365   Joshi K B;Patel N N (Physics Dep, Univ College of Science, Udaipur-313 001, Email: k_joshi@yahoo.com) : Charge density fo Ga_xAl₁-_xSb. Pramana J Phys 2008, 70(2), 295-305.

Charge density calculations and electronic band structures for GaAlSb with x = 1.0, 0.5 and 0.0 are presented in this work. The calculations are performed using the empirical pseudopotential method. The charge density is computed for a number of planes, i.e. z = 0.0, 0.125 and 0.25A by generating the potential through a number of potential parameters available in the literature. The virtual crystal approximation was applied for the semiconducting alloy. The characteristics of the band structure and charge density are observed to be affected by the potential parameters. Calculated band gaps and the nature of gaps are in good agreement with the experimental data reported. The ionicity is also reasonably in good agreement with other scales proposed in the literature; however the formulation needs to be improved.Also demands indirect experimental band gap for the alloy.

10 illus, 2 tables, 17 ref

008364   Joshi A;Gangal S A;Aswal D K;Kaur M;Gupta S K;Yakhmi J V (Electroni Science Dep, Pune Univ, Pune) : Room temperature chlorine gas sensing properties of polypyrrole - ZnO composite thin films. BARC Newsl 2009, 309(Oct; spl), 331-4.

Chlorine gas sensing characteristics of polypyrrole and Polypyrrole-ZnO nanowire composite thin films have been studied. The composite films were synthesized by drop casting method. The films were characterized for its morphology as well as gas sensing characteristics for different gases such as H₂S, NH₃, CH₄, CO and NO at room temperature. The composite films were found to be more sensitive to chlorine than pure polypyrrole. They were also selective for chlorine gas over other gases. This indicates composite films can be used as room temperature chlorine sensor.

3 illus, 10 ref

008363   Jayannavar A M;Sahoo M (NO, Institue of Physics, Sachivalaya Marg, Bhubaneswar-751 005, Email: jayan@iopb.res.in) : Fluctuation theorems and orbital magnetism in nonequilibrium state. Pramana J Phys 2008, 70(2), 201-10.

Studies Langevin dynamics of a driven charged particle in the presence as well as in the absence of magnetic field. Discuss the validity of various work fluctuation theorems using different model potentials and external drives. Also shows that one can generate an orbital magnetic moment in a nonequilibrium state which is absent in equilibrium.

4 illus, 32 ref

008362   Gogoi P;Dixit P N;Agarwal P (Physics Dep, Indian Institute of Technology Guwahati, Guwahati-781 039, Email: pratima@iitg.ernet.in) : Transport and stability studies on high band gap a-Si:H films prepared by argon dilution. Pramana J Phys 2008, 70(2), 351-8.

Device quality hydrogenated amorphous silicon films (a-Si:H) are deposited at a high deposition rate (4-5 Angstrum/s) using a mixture of argon and hydrogen-diluted silane. The films exhibit good opto-electronic properties and show less degradation upon light soaking. Light-induced changes in conductivity could be annealed at much lower temperature. The presence of Ar* and atomic hydrogen in plasma replaces the weak Si-Si bonds, which are responsible for light-induced degradation by strong Si-Si bonds. This results in the improved stability of the films.

6 illus, 1 table, 13 ref

008361   Geetha D;Thilagavathi T;Ramesh P S;Rakkappan C (Physics Dep, Annamalai Univ, Annamalainagar-608 002, Email: gee_d72@yahoo.co.in) : Acoustical studies of solutions of surfactant-polymer in ehanol. Ultra Scient phys Sci 2009, 21(2), 239-44.

Ultrasonic velocity measurements have been made in an anionic surfactant sodium laureyl sulphate (SLS) with Dextrin (Dx), Hydroxy ethyl cellulose (HEC) and Hydroxy Propyl cellulose (HPC) in ethanol solution as a function of concentration, at a fixed frequency (2MHz). SLS with different polymers are prepared and dissolved in different concentration ratio (1:9 to 9:1). Limiting parameters have been used to explain the salvation of surfactant-polymer molecules.

2 illus, 3 tables, 10 ref

008360   Gajbhiye N S;Ningthoujam R S;Ahmed A;Panda D K;Umare S S;Sharma S J (Chemistry Dep, Indian Institue of Technology, Kanpur-208 016, Email: rsn@barc.gov.in) : Re-dispersible LI<. Pramana J Phys 2008, 70(2), 313-21.

Re-dispersible CdS, 5 at.% Eu³⁺-doped CdS, 2 at.% Li⁺ and 5 at.% Eu³⁺ cb-doped CdS nanoparticles in organic solvent are prepared by urea hydrolysis in ethylene glycol medium at a low temperature of 170°C. CdS nanoparticles have spherical shape with a diameter of ±80 nm. The asymmetric ratio (A₂₁) of the integrated intensities of the electrical dipole transition to the magnetic dipole transition for 5 at.% Eu³⁺-doped CdS is found to be 3.8 and this ratio is significantly decreased for 2 at.% Li⁺ and 5 at.% Eu^{3+ co-doped CdS (A₂₁ = 2.6). It establishes that the symmetry environment of Eu3+ ion is more favored by Li-doping. Extra peak at 550 nm (green emission) could be seen for 2 and 5 at.% Eu3+ co-doped CdS. Also, the significant energy transfer from host CdS to Eu3+ is found for 5 at.% Eu3+-doped CdS compared to that for 2 at.% Li+ and 5 at.% Eu3+ co-doped CdS.}

9 illus, 25 ref

008359   Gajbhiye N S;Bhattacharyya S;Sharma S (Chemistry Dep, Indian Institute of Technology, Kanpur-208 016, Email: nsg@iitk.ac.in) : Observation of exchange bias and spin-glass-like ordering in ε-Fe_2.8Cr_0.2N nanoparticles. Pramana J Phys 2008, 70(2), 367-73.

Nanoparticles of ε-Fe_2.8Cr_0.2N system exhibit the exchange bias phenomenon due to the exchange coupling of the spins of the antiferromagnetic (AF) oxide/oxynitride surface layer and the ferromagnetic (FM) nitride core. Exchange bias is observed at 10 K both in the absence and presence of cooling field. Due to the interface disorder, a mixture of parallel and anti-parallel/perpendicular coupling of the AF and FM spins is observed. The roughness of AF-FM interface induces disorder due to the random exchange anisotropy. The saturation magnetization is also found to be drastically lowered as compared to parent ε-Fe₃N. Below 58 K, the broad peak (TE @ T_f) in zero-field cooled (ZFC) magnetization curves indicates the presence of unidirectional anisotropy and spin-glass-like ordering, that arises from the freezing of localized frustrated spins.

5 illus, 16 ref

008358   Deokar U V;Mathew P;Kulkarni V V;Deshpande M D (Health Physics Div, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : Radiological safety aspects during operation of the advanced vitrification system (AVS), at Tarapur. BARC Newsl 2009, 309(Oct; spl), 194-8.

Advanced Vitrification System (AVS) is designed for vitrification of High Level Waste (HLW) generated in reprocessing plant operation, by using Joule Heating Ceramic Melter for the first time in India. Glass frits are used for vitrification. Health Physics Unit of WMF, Tarapur was involved in planning, setting up and operation of the radiological surveillance system, since the inception of the AVS facility. This paper summarizes the radiological safety asp during production of 100 vitrified waste products in AVS. Vitrification of the concent: High Level Waste started on 11th August, 2006 and completed 1 00 operations on 2008. Around 4.13 million curries (153070 TBq) gross beta activity, was vitrified in canisters.

3 tables

008357   Choudhury S D (Radiation & Photochemsitry Div, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : Photoinduced electron transfer kinetics in confined systems and modulation by an external magnetic field. BARC Newsl 2009, 309(Oct; spl), 157-62.

Photoinduced Electron Transfer (PET) reactions have been studied in the presence of an external magnetic field, in order to identify the mechanism and dynamics of such reactions. It has been demonstrated that not only the structure of the participating molecules, but also the topology of the medium can have a profound influence on the magneto-dynamics of electron transfer reactions. The elusive Marcus inverted region has also been observed for bi-molecular PET reactions in some confined media.

3 illus, 16 ref

008356   Choudhary S K;Gupta A K (Physics Dep, Indian Institute of Technology, Kanpur-208 016, Email: shyamkc@iitk.ac.in ) : Some unusual electronic patterns on graphite surface. Pramana J Phys 2008, 70(2), 339-50.

Reports on the observation of some unusual electronic patterns on a graphite surf ace using scanning tunneling spectroscppy (STM). Attribute these patterns to different types of strain near the surface.One such pattern seen on a particular layer comprises of two-dimensional spatially varying super-lattice and one-dimensional fringes. This pattern is present in a finite region of a layer on the surface confined between two carbon fibers. Attribute this spatially varying super-lattice structure to the shear strain generated in the top layer due to the restraining fibers. Also developed a model with the Moire rotation hypothesis that gives us a better insight into such large-scale spatially varying patterns. Also able to model the above-observed pattern. Also report another pattern near a defect, which we attribute to the change in density of states due to the physical buckling of the top graphite layer. Part of this buckled layer is found to be buried under another layer and this region shows a reversed contrast and thus supporting our idea of buckling.Also performed tunneling spectroscopy measurements on various regions of these patterns which show significant variations in the density of states.

9 illus, 16 ref

008355   Chauhan R;Sadhna Singh (NO, Truba Institute of Engineering and Information Technology, Karod-Gandhinagar Bypass Road, Bhopal-462 038) : Structural study of novel (superhard) material : NiO. Pramana J Phys 2008, 70(2), 307-11.

Investigates the pressure-induced phase transition of NiO and other structural properties using three-body potential approach. NiO undergoes phase transition from B1 (rocksalt) to B2 (CsCl) structure associated with a sudden collapse in volume showing first-order phase transition. A theoretical study of high pressure phase transition and elastic behaviour in transition metal compounds using a three-body potential caused by the electron shell deformation of the overlapping ion was carried out. The phase transition pressure and other properties predicted by our model is closer to the phase transition pressure predicted by Eto et al.

1 illus, 2 tables, 10 ref

008354   Chaddah P;Banerjee A (NO, UGC-DAE Consortum for Scientific Research Campus Univ, Khandwa Road, Indore-452 017, Email: chaddah@csr.ernet.in) : Tunable two-phase coexistence in half-doped manganite. Pramana J Phys 2008, 70(2), 193-9.

Discuss interesting experimental observation that the low-temperature two-phase coexistence in half-doped manganites is multi-valued (at any field) in that we can tune the coexisting antiferromagnetic-insulating (AF-I) and the ferromagnetic-metallic (FM-M) phase fractions by following different paths in (H,T) space. Shown experimentally that the phase fraction, in this two-phase coexistence, can take continuous infinity of values. All but one of these are metastable, and two-phase coexistence is not an equilibrium state.

5 illus, 13 ref

008353   Bhushan K G;Gadkari S C;Yakhmi J V;Sahni V C (Technical Physics and Prototype Engineering Div, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : Novel electrostiatic ion trap and Fourier transform measurements for high-resolution mass spectrometry. BARC Newsl 2009, 309(Oct; spl), 101-7.

Reports on the development of a novel electrostatic ion trap for high-resolution mass spectrometry. The ion trap works on purely electrostatic fields, thereby allowing simultaneous trapping and studying of multiple mass species, over a large mass range. Ions are trapped and stored as a bunch between two collinearly placed electrostatic ion mirrors and oscillate continuously. The oscillatory signals are fourier-transformed to produce the frequency spectrum, wherein each frequency corresponds to a particular mass of the trapped ions. From the initial experiments a mass resolving power (m/Δm) of about 20,000 and a storage lifetime of about 100ms is observed. This unique feature and several other important characteristics of this ion trap are presented, along with its application as a high resolution mass spectrometer.

6 illus, 16 ref

008352   Behere A;Joy S;Jha K;Raut S M;Meshram M L; Nair P;Pande S S;Padmini S (Electronic Div, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : CAMAC instrumentation for accelerator based nuclear physics research experiments. BARC Newsl 2009, 309(Oct; spl), 62-70.

BARC has developes and supplies a number of CAMAC modules and systems for accelerator-based multi-parameter experiments for more than a decade. These mainly include PC-CAMAC AMPS, Nuclear ADCs and FERA-based system. These systems have been installed at Pelletron accelerator at TIFR, Mumbai and other accelerator facilities at VECC, Kolkata, IOP, Bhubaneswar, etc. They provide an indigenous solution for the high performance requirement of resolution and throughput for the experiments. A. new Embedded Crate Controller has been developed, to achieve higher performance through hardware list sequencing. It has also alleviated the problem of component obsolescence in earlier versions of controllers. The recently developed and commissioned FERA system, targets higher throughput experiments spanning multiple CAMAC crates.

13 illus

008351   Asgari R;Tanatar B (School of Physics, Institute for Studies in Theoretical Physics and Mathematics, 19395-5531 Tehran, Iran, Email: asgari@theory.ipm.ac.ir) : Quasi-particle properties in a quasi-two-dimensional electron liquid. Pramana J Phys 2008, 70(2), 285-93.

Consider the quasi-particle properties such as the effective mass and spin susceptibility of quasi-two-dimensional electron systems. The finite quantum well width effects are incorporated into the local-field factors that describe the charge and spin correlations. Employ the Fermi-hypernetted chain formalism in conjunction with fluctuation-dissipation theorem to obtain the local-field factors. Our results are in good agreement with recent experiments.

3 illus, 31 ref

008350   Arkhincheev V E (Buryat Science Center of Russian Academy of Sciences, Str. Sakhyanovoi 6, Ulan - Ude, 670047 Russia, Email: varkhin@yahoo.com) : Bound values for hall conductivity of heterogeneous medium under quantum hall effect conditions. Pramana J Phys 2008, 70(2), 271-7.

Bound values for Hall conductivity under quantum Hall effect (QHE) conditions in inhomogeneous medium has been studied. It is shown that bound values for Hall conductivity differ from bound values for metallic conductivity. This is due to the unusual character of current percolation under quantum Hall effect conditions.

2 illus, 8 ref

008349   Aggarwal S K;Alamelu D;Parab A R;Shahi Bhushan K (Fuel Chemistry Div, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : Studies on the application of internal normalization in the determination of uranium isotopic ratio using oxygen isotopic ratio. BARC Newsl 2009, 309(Oct; spl), 205-8.

Describes a new methodology of internal normalization, to correct for the isotopic fractionation of U, using UO⁺ions for obtaining isotopic analysis data for U. The methodology is promising for application to U isotopic analysis by TIMS. The suitable conditions for application of this method are also discussed.

4 illus

006143   Yadav R P;Harminder Singh;Bhoopal Singh (Physics Dep, Govt. P.G.College, Bisalpur-262 201, Email: rpyadav93pphysics@yahoo.co.in) : Experimental studies on the blood flow in stenosis arteries in presence of magnetic field. Ultra Scient phys Sci 2008, 20(3), 499-504.

An experimental model of blood flow in stenosis artery under the action of an applied axial magnetic field is proposed. A variable magnetic field ranging from 5.46 - 21.84 gauss is used to conduct the experiment. This model consist with the principles of ferrohydrodynamics and magne-tohydrodynamics and takes into account the magnetization property of blood. The flow is appreciably influenced by the application of the magnetic field. A comparison of the derived results is also taken into account.

1 illus, 2 tables, 12 ref

006142   Tripathi R K;Singh Jai;Singh P K (Mathematics Dep, Allahabad Univ, Allahabad-211 002, Email: rkt_au@rediffmail.com) : Chemical reaction effects on the flow past an infinite plate in porous medium with constant heat flux. Ultra Scient phys Sci 2008, 20(3), 431-6.

An analysis has been carried out for a two dimensional, incompressible viscous flow in a porous medium with variable permeability past an infinite plate with constant heat flux and chemical reaction effects. An analytical solution has been obtained by introducing non-dimensional parameters. The effects of permeability and chemical reaction parameters on the flow field has been obtained and discussed with the help of graphs.

5 illus, 10 ref

006141   Tiwari S N;Dwivedi A K;Shukla S N (Physics and Electronics Dep, Dr. R.M.L. Avdha Univ, Fizabad-224 001, Email: sachida_shukla@yahoo.co.in) : Qualitative analysis of modified darlington amplifier. Ultra Scient phys Sci 2008, 20(3), 625-9.

Modification in Darlington pair amplifier is proposed by adding an extra biasing resistance R_D in the conventional circuit. This simultaneously produces high voltage gain and wide bandwidth. Proposed modification also removes the consequences of conventional Darlington pair amplifier at higher frequencies. Proposed amplifier may be useful for amplification of small signals in mid frequency range and beneficial for various analog communication applications.

7 illus, 9 ref

006140   Srivastava S K;Amar Bahadur;Singh S P;Singh A K (Physics Dep, Kamla Nehru Institute of Physical and Social Sciences, Sultanpur, Uttar Pradesh, Email: amar.b.007@gmail.com) : Plasmon excitation inphoton excited K_α X-ray satellite spectra of Si and Sio₂. Ultra Scient phys Sci 2008, 20(3), 587-92.

Investigated photon excited K_α x-ray satellite spectra of Si and SiO₂ using plasmon theory. The KαL¹/ KαL° and KαL² / KαL° intensity ratio are found to be agreed well with experimentally observed values. In the calculation of relative intensity; intrinsic, extrinsic and their relative contributions have been discussed.

2 tables, 32 ref

006139   Singh V;Satyendra Singh;Gaur K (Physics Dep, K.N. Govt. P.G. College, Gyanpur, Bhadohi) : High lithium ion conductivity in the system Li₂O : V₂O₅ : WO₃. Ultra Scient phys Sci 2008, 20(3), 559-64.

Electrical conductivity (a) and Seebeck Coefficient (S) studies have been reported from 500 K to the melting point (1150 K) the solidified melt of the superionic system Li2O : X₂O₅: WO₃. The material is not hygroscopic and does not have a real superionic phase, however, in the temperature range 320 K to 550 K it has high ionic conductivity (σ_i, = 2.1 x 10^-2 Ω^-1 m^-1 at 330K) with small (0.21 eV) activation energy but relatively large (between 10 to 15 percent) electronic conductivity. Anomaly observed in σ and S data is also reflected in molar magnetic susceptibility (χ_M) and dielectric constant (K) results.

4 illus, 22 ref

006138   Pensia R K;Ghorela V;Chhajlani R K (Physics Dep, Govt. P.G. College, Neemuch-0458 4416, Email: Vishalsurati2000@yahoo.com) : Thermal Instability of a self gravitating, rotating gaseous plasma with generalized Ohm's law. Ultra Scient phys Sci 2008, 20(3), 541-4.

Thermal instability of an infinitely homogeneous, Self gravitating, rotating gaseous plasma has been investigated here in the presence of the effects of Generalised ohm's law and viscosity. The dispersion relation has been obtained for parallel propagation and numerical calculation has been performed to obtain the dependence of the growth rate on the various physical effects. It is found that, in the case of parallel by a transverse magnetic field and axis of rotation is taken along the direction of magnetic field, the growth of instability is independent of the magnetic field.

10 ref

006137   Pandit S R;Prasad L B;Singh S S;Mandal K K (Physics Dep, S.K.M. Univ, Dumka (Jharkhand)) : Effect of electron-phonon interaction on semiconduction carbon nanotubes. Bull phy Sci 2009, 5(1), 33-6.

Carbon nanotubes have the highest theory^{8 strength which are more then hundred times that of steel, although specific gravity are only one sixth that of the latter carbon nanotubes have special advantages in the field of shielding and absorbing electromagnetic radiation, field emission, thermal conducting, hydrogen storing adsorbing catalyzing etc. In the present communication, the effect of electron-phonon interaction of semiconducting carbon nanotubes have been studied under the influence of electromagnetic radiation. The potential to create an entirely green energy system, solar cells and fuel cells powered by fullerenes and anotubes produced from biofuels.}

14 ref

006136   Pandit S R;Mandal K K;Singh S S;Prasad L B (P.G. Physics Dep, S.K.M. Univ, Dumka (Jharkhand)) : Theoretical study on the behaviour of electronic states of heterojunctions and quantum dots on carbon nanotubes under magnetic fields. Bull phy Sci 2009, 5(1), 29-32.

The communication is an attempt to study on the behavior of electronic states of heterojunctions and quantum dots on carbon nanotubes under magnetic fields. The theoretical capability was envisioned as early as 1959 by the renowned physicist Richard Feynman.^{9 SWNTs come in many structural forms and their electronic properties vary with differences in their structures. Each batch that is produced by Smalley's Hipco process contains about 50 different species of nanotubes each within a characteristic diameter and chiral angle- the angle at which is rolled. Armchair SWNTs are also metallic in electronic character.}

12 ref

006135   Pandit S R;Mahto S B;Mahto J P;Mandal K K; Singh S S (P.G. Physics Dep, S.K.M. Univ, Dumka (Jharkhand)) : Survey for the determination of fermi energy and concentration of conduction electrons of alkali metals. Bull phy Sci 2009, 5(1), 1-5.

The study presents the results and expected conclusion for the determination of Fermi energy and concentration of conduction electrons of alkali metals at low temperatures. A close examination in the light of observed Fermi energy of alkali mental has found its success in many cases and failure in a few other cases [Berman and Mac Donald^{3, Hulm10, cezairliyan5, Cezairliyan & Toulouskian6]. An improvement in the generality of the determination of Fermi energy may be expected by the introduction of the contribution due to impurities and thermal motions of atoms. The previous idea regarding the electrons as the principal carriers of heat in metals even at sufficiently low temperatures appears to be shunted by the results.}

2 tables, 18 ref

006134   Pandit R S;Mahto S B;Mahto J P;Yadav S K; Mandal K K (Physics Dep, C.N. College, Ramgarh (Jharkhand), Email: mahto_1969@rediffmail.com) : Reversibility of Peltier and Thomson effects in a thermocouple. Bull phy Sci 2009, 5(1), 23-7.

The communication is concerned with the thermoelectric phenomena in metals and thermocouples at normal temperature. It has been focused on the reversibility of the Peltier and the Thomson effects. The sources of the thermoelectric effects and theoretical relations suggested for them have been reviewed on the light of experimental findings.

1 table, 12 ref

006133   Palani R;Geetha A;Balakrishnan S;Jayanthi C (Physics Dep, D.D.E., Annamalai Univ, Annamalainagar-608 002, Email: palani_physics06@yahoo.co.in) : Physico-chemical behaviour of some aromatic amines in 1-propanol mixture at 303.15 K. Ultra Scient phys Sci 2008, 20(3), 505-12.

Density (ρ), viscosity (η) and ultrasonic velocity (U) have been carried out in three binary liquid mixtures for aniline, 2-chloro aniline and 3-chloro aniline with a polar compound of 1 -propanol at 303.15 K. The experimental data have been used to calculate the adiabatic compressibility (β5), free length (L_f), free volume (V_f), internal pressure (π₁), Gibb's free energy (ΔG), Grunberg interaction parameter (d) and their excess values. The results of excess parameter can be discussed in the light of intermolecular interaction in the binary mixtures.

6 illus, 2 tables, 17 ref

006132   Palani R;Geetha A;Balakrishnan S;Catherine M (Physic Dep, D.D.E., Annamalai Univ, Annamalainagar-608 002, Email: plani_physics06@yahoo.co.in) : Acoustical studies on ion-solvent interaction of some electrolytes in aqueous DMF mixed solvent system at different temperatures. Ultra Scient phys Sci 2008, 20(3), 485-92.

Density (ρ), viscosity (η) and ultrasonic velocity (U) have been measured for sodium halide solutions namely sodium fluoride (NaF), sodium chloride(NaCl), sodium bromide (NaBr) in aqueous dimethylformamide (DMF) (1m) at 303, 308 and 313K. Using the experimental values, the adiabatic compressibility (β), hydration number (n_H), apparent molal compressibility ), apparent molal volume ( φ_v ), limiting apparent molal compressibility ), limiting apparent molal volume ( (φ⁰_V ) and their constants (S_K, S_v) and viscosity A and B coefficients of Jones-Dole equation were calculated and the results have been discussed in terms of ion-solvent interactions.

3 tables, 18 ref

006131   Pal T;Bandopadhaya P C;Mitra S K;Raghav S (Geological Survey of India, Salt Lake, Kolkata-700 091, Email: tapanpal_in@yahoo.co.uk) : The 2005 eruption of barren volcano: an explosive inner arc volcanism in Andaman sea. J Geol Soc India 2007, 69(6), 1195-1202.

The 2005 eruption of Barren Volcano was explosive and pulsative Strombolian type (15-30 seconds interval). A thick column of grey smoke along with red-hot pyroclasts was found ejecting out with rumbling sound from the crater. The eruption column of ash particles attained a height of more than 300 m, whereas larger pyroclasts were ejecting out to about 100 m above the crater. The assorted mixture of air fall tephrain the form of blocks, cinders, lapilli and spatter along with ash formed two cinder cones. Pyroclasts are of basaltic composition and show vitrophyric texture with phenocrysts of plagioclase, olivine and diopside set in a glassy groundmass. EPMA of the mineral phases shows that plagioclase phenocrysts are represented by anorthite (An 94.5) and bytownite (An81.6-89.0),whereas in the groundmass, feldspar microlites are labradorite (An57.3). Compositionally olivines are forsteritic (Fo72-79), and the clinopyroxenes as phenocrysts are diopside and clinopyroxenes in groundmass as pigeonite. Major oxide analyses of the bulk pyroclastics show that the basalts are high alumina basalt of Island Arc Tholeiitic (IAT) affinity Mineralogical as well as chemical similarities of these basalts with lavas of earlier eruptions from Barren Volcano suggests no major change in magmatic evolution with time in the inner arc setting of Andaman subduction complex.

8 illus, 3 tables, 13 ref

006130   Pachauri A K (Earth Sciences, Indian Institute of Technology, Roorkee-247 667, Email: ashokfes@iitr.ernet.in) : Facet based landslide hazard zonation (LHZ) maps for the Himalayas: example from Chamoli region. J Geol Soc India 2007, 69(6), 1231-40.

Discusses the facet based Landslide Hazard Zonation (LHZ) methodology with an example from Chamoli region in Higher Himalayas. It is based on hierarchical classification of terrain into homogenous units called facet (Pachauri 1970,1998; Pachauri and Krishna 1984; Pant and Pachauri 1989; Pachauri, 2001; Wagner 1981; Wagner et al. 1987;Deoja et al. 1991). Facets are essentially slopes of varying degrees mapped at 1:50,000 or larger scales. The weighted rating of parameters like slope angle, distance from ridge and others, is taken into account for arriving at a cumulative score for each slope facet. A landslide hazard zonation map can be prepared with zones of hazard values related to relative intensities, using different colour, pattern or shades. The scheme is suitable for high relief terrain like the Himalayas and the Nilgiri Hill region and application of this work spans the Himalayan terrain of Nepal and Bhutan. The methodology is essentially based on geological parameters and is easy to apply in two steps: I. Classification of terrain, and II. Landslide Hazard Zonation using cumulative scores. It is both cost effective and cheap.

6 illus, 36 ref

006129   Ogra K;Lalmani;Koul B L (Physics Dep, National Institute of Technology (Srinagar), Camp Classes, Old Univ Campus, Canal Road, Jammu-180 014) : Ultrasonic study of aqueous potassium citrate. Ultra Scient phys Sci 2008, 20(3), 437-45.

Measurement of the acoustics wave velocity through a fluid combined with physical properties of the medium such as its density, temperature and pressure provide information about thermodynamic parameters of the fluid such as: specific acoustic impedance (Z), adiabatic compressibility (β), apparent molal compressibility (φ(k)), molar sound velocjlx (R), inter-molecular free length (L_fn). The estimation of the thermodynamic parameters in aqueous solutions of electrolytes of different valence types has been carried and the dependence of these parameters on cationic and anionic radii established. In the case of an electrolyte having anionic radius of 18.75 Angstrum and cationic radius of 1.33 Angstrum, the changes observed in the parameters have been studied, which provide an insight into the influence of cationic size on these parameters. It is found that the size of the cation appreciably influences these parameters.

1 illus, 4 tables, 32 ref

006128   Mondal P;Ghosh S (Physics Dep, Nizam College, Osmania Univ, Hyderabad-500 001, Email: saisum@hotmail.com) : Diffraction images of truncated square-wave periodic objects formed by a human eye in the presence of Stiles-Crawford effect-I. Natn Acad Sci Lett 2008, 31(5-6), 197-200.

An expression that gives the intensity distribution in the diffraction images of truncated, one-dimensional periodic objects with square-waveform, formed by the human eye in the presence of Stiles - Crawford Effect of the First Kind has been derived using optical transfer function approach. The object is considered to be incoherent. We have also evaluated the Modulations in the images and average irradiance.

2 illus, 1 table, 7 ref

006127   Mishra S B;Mohanty P C;Mishra P K;Patnaik A K (Chemistry Dep, Utkal Univ, Bhubaneswar, Orissa) : Viscosity studies of Cu(NO₃)₂.3H₂O in propan-2ol+water solvent at 303.15 K. Ultra Scient phys Sci 2008, 20(3), 545-8.

The viscosity of the Cu(NO₃)₂.3H₂O at 10%, 20% and 30% (w/w) of Propan-2-ol +Water mixtures at 30°, 35° and 40° C has been measured. The ions appear to interact and the ion-solvent interaction or structure-breaking effect of the anions changes with the change in Propan-2-ol content.

2 tables, 8 ref