001074   Muthcurmaraswamy R;Ganesan P;SOundagekar V M (Dep Math Computer Applic, Sri Venkateswara College of Engineering, Sriperumbudur-605 105) : The study of flow past an impulsively started isothermal vertical plate with variable mass diffusion. J Energy Heat Mass Transfer 2001, 23(1), 63-72.

An exact solution to the problem of flow past an impulsively started infinite isothermal vertical plate in the presence of variable mass diffusion is presented by the Laplace-transform technique. The velocity, temperature and concentration profiles are studied for different parameters like thermal Grashof number, Prandtl number, Schmidt number and for multiple buoyancy effects aiding and opposing. It is observed that the skin-friction increases in the presence of opposing flows and decreases with aiding flows. The values of the skin-friction are tabulated.

5 illus, 6 ref

001073   Mohamed K A (Dep Phys, Aligarh Muslim Univ, Aligarh-202 002) : New hot bands in high resolution FTIR spectrum of <. Indian J pure appl Phys 2002, 40(11), 765-9.

The high resolution Fourier transform infrared spectrum of ¹³C2H₂ shows several bands in the 3 μm region. Some bands were reported earlier. A few new hot bands have been identified and assigned. The line positions of these bands, the rotational constants and the centrifugal distortion constants of the upper and lower states involved in the transitions, and the effective l-doubling constants q4 and q5 have also been reported.

2 illus, 6 tables, 9 ref

001072   Modi K B;Joshi H H (Department of Physics, Saurashtra University, Rajkot-360 005 Gujarat) : Compositional and temperature dependent electrical behaviour of zinc- substituted copper- ferri-chromates. Indian J Phys-Pt A 2002, 76(6), 543-7.

The compositional and thermal variation of electrical properties of Zn_xCu_1-xFeCrO₄ (x=0.0, 0.2, 0.4, 0.6) spinel ferrite system were studied by means of d.c. resistivity and thermoelectric power measurements. The electrical parameters like Fermi - energy charge carrier concentration and mobility were determined and probable conduction mechanism in the system has been suggested

3 illus, 28 ref

001071   Mehta G K (NO, University of Allahabad, Allahabad-211 002) : Heavy ion accelerator and associated developments in India. Pramana J Phys 2002, 59(5), 703-12.

Developments of ion accelerator and associated facilites in India are presented. Various types of accelerator facilities which are systematically built in the country through sustained development and research programs at various research centres and institutions are highlighted. Impact of accelerator in different interdisciplinary fields of research are highlighted.

^iia1 table

001070   Manohar D;Nagarajan A S;Ramakrishna S; SOundalgekar V M (Dep Math, S. V. Univ, Tirupati-517 502) : Mass transfer effects on free convection flow of an incompressible viscous dissipative fluid. J Energy Heat Mass Transfer 2001, 23(4), 445-54.

A finite difference solution of mass transfer effects on free convection flow of an incompressible viscous dissipative fluid past an infinite vertical plate, on taking into account viscous dissipative heat, is presented. The velocity profiles, the temperature profiles and the concentration profiles are shown on graphs for different values of Pr, E, t and Sc. The numerical values of the skin friction, the rate of heat transfer and the rate of mass transfer are entered in tables. It is observed that greater values of Sc leads to a fall in the velocity, temperature and concentration. An increase in Pr leads to fall in skin fiction and rate of heat transfer, where as rate of mass transfer increases as Pr increases.

10 ref

001069   Manam J;Singh A K;Sharma S K (Department of Applied Physics, Indian School of Mines, Dhanbad-826 004) : Thermally stimulated luminescence studies of undoped, Cu and Mn doped lithium borate compounds.. Indian J Phys-Pt A 2002, 76(6), 549-52.

Thermally stimulated luminescence (TSL) studies of undoped. Cu and Mn doped Li₂B₄O₇ are reported. The polycrystalline samples of undoped and doped Li₂B₄O₇ were prepared by melting method. The formation of the undoped compound was checked by X-ray differaction and Fourier transforms infrared (FTIR) studies. The compound has orthorhombic structure at room temperature. In TSL studies undoped sample exhibits two glow peaks at the temperatures 190 and 280°C. The Cu-doped lithium tetraborate sample exhibits three glow peaks at the temperature 185, 290 and 350°C whereas the Mn doped sample exhibits glow peaks at 190 and 300°C. The results show that Cu-doped Lithium tetraborate is more sensitive and the TSL intensities of 185 and 290°C flow peaks in Cu doped Li₂B₄O₇ are enhanced by about 25 and 10 times respectively when compared with the corresponding glow peak intensities in undoped Li₂B₄O₇.

5 illus, 12 ref

001068   Mallick P S;Mukhopadhyay D (Department of Electronics and Communication Engineering, National Institute of Science and Technology, Palur Hills, Berhumpur-761 008) : Monte carlo calculation of electron transport in InSb. Indian J Phys-Pt A 2002, 76(6), 553-5.

The velocity field characteristics of InSb have been obtained at 77K by the Monte Carlo simulation technique. The results agree with the experimental data and also with those obtained by using the diosplaced Maxwellian distribution function. The effects of the various simulation parameters as well as that of the ionized impurity concentration on the mobility values for InSb have been discussed and results presented.

2 illus, 7 ref

001067   Lin C S (Dep Auto Control Engng, Feng Chia Univ, Taichung Taiwan) : Pilot-type scientific experimental device using optical method and computer vision technology. Indian J pure appl Phys 2002, 40(11), 816-27.

Digital image and mutlimedia technology projected in a modified laser shadow spot set-up to guide people to engage in the scientific model of the crack growth has been described. This novel device can be operated automatically, and economically in a participating display. A new method to process the experimental data and predict the fracture time in the PC-based digital signal processing system has been developed. With one video CCD camera and frame grabber analyzing a series of images of laser shadow spot during crack growth, the computers obtain the image size of laser shadow spot to evaluate stress intensity factor in real time. An auto-range finding algorithm is used to find the location of a laser shadow spot. Six special experimental conditions have been considered to improve this scientific model. Participants can operate the model themselves, so that they can observe the change of sizes of the laser shadow spot images and can respond in time to know the status of specimen in tension. It also can remind the attention of the participant with the sign of a speech sound before the break of specimen to achieve the effect during recreation to learn.

21 illus, 2 tables, 17 ref

001066   Lay Y L;Lin C S (Dep Electronic Engng, Natn Chin-Yi Inst Tech, Taichung, Taiwan, ROC) : Lens distortion correction by adjusting image of calibration target. Indian J pure appl Phys 2002, 40(11), 770-4.

The dilemma of lens distortion in computer vision is a common and serious phenomenon, especially when a lens captures a wide-angle image or when an object is seized within a limited range. Using correction lens, phase plates or holographic gratings, mainly, makes the corrections. However, it is extremely difficult to accurately correct the distortion using attached optic components because the design of these components is complicated and commercially hard to attain. A method is proposed to correct the distortion using the lens aberration theory and image processing techniques. A calibration target is taken as the correct and acceptable objective. The captured or seized image of the calibration target is not equally divided as original and this pixels-shift contains the distortion information which could be corrected by an image process software.

4 illus, 1 table, 7 ref

001065   Lau S C;Moon S W (Dep Mech Engng, Texas A&M Univ Coll Stn, Texas-77843-3123) : Effect of dimple geometry on flow and heat transfer in a square channel with a dimpled wall. J Energy Heat Mass Transfer 2001, 23(4), 393-416.

Dimpled surfaces may be considered for heat transfer enhancement in internal cooling of gas turbine airfoils. Heat transfer and flow characteristics of dimpled surfaces, for turbulent airflow in a square channel with concave or cylindrical dimples on one of the walls, were studied. Experiments were conducted to determine the average heat transfer coefficient on the dimpled wall and the overall pressure drop across the channel, for four concave and cylindrical dimples with a fixed diameter and two different depths, and for Reynolds numbers. between 10,000 and 65,000. Numerical results were obtained for turbulent airflow through a square dimpled channel with dimple geometries and boundary conditions that were the same as those for the experiments. The cylindrical dimples caused higher heat transfer than the concave dimples. The numerical results showed the highly complex and unique flow patterns near the surfaces with the concave and cylindrical dimplex and inside the cavities of these dimples. The numerical results also showed that cylindrical dimple configuration might be a better alternative than concave dimples in enhancing heat transfer.

12 illus, 10 ref

001064   Kurup M B (Nuclear and Atomic Physics Dep, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai-400 005) : Development of a superconducting LINAC booster for the pelletron at Mumbai. Pramana J Phys 2002, 59(5), 811-20.

Superconducting linear accelerator (LINAC) to boost the energy of the heavy ion beams from the 14 UD pelletron accelerator at Mumbai is under development. The booster is based on quarter wave resonators (QWR) coated with lead which is superconducting at liquid helium temperature. The operating frequency is 150 MHz. Four resonators each are mounted in a cryostat module built indigenously. A total of seven such modules arranged in two arms with an isochronous and achromatic beam bend in the middle comprises the full LINAC. The transverse focusing of the beam through the LINAC is carried out using periodic quadrupole doublet magnets operating at room temperature. The present status of the project is described.

8 illus, 4 ref

001063   Kumar P;Rodrigues G;Rao U K;Safvan C P; Kanjilal D;Roy A (Nuclear Science Centre, , Aruna Asaf Ali Marg, New Delhi-110 067) : ECR ion source based low energy ion beam facility. Pramana J Phys 2002, 59(5), 805-9.

Mass analyzed highly charged ion beams of energy ranging from a few keV to a few MeV plays an important role in various aspects of research in modern physics. A unique low energy ion beam facility (LEIBF) set up at Nuclear Science Centre (NSC) for providing low and medium energy multiply charged ion beams ranging from a few keV to a few MeV for research in materials sciences, atomic and molecular physics is described. One of the important features is the availability of relatively large currents of multiple charged positive ions from an electron cyclotron resonance (ECR) source placed entirely on a high voltage platform. All the electronic and vaccum systems related to the ECR source including 10 GHz ultra high frequency (UHF) transmitter, high voltage power supplies for extractor and Einzel lens are placed on a high voltage platform. All the equipments are controlled using a personal computer at ground potential through optical fibers for high voltage isolation. Some of the experimental facilities available are also described.

2 illus, 1 table, 5 ref

001062   Karan S;Sen Gupta S P (Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700 032) : Deffect characterizations in solution-grown single crystals of magnesium sulphate heptahydrate (MgSO₄, 7H₂O) by chemical etch technique. Indian J Phys-Pt A 2002, 76(6), 561-5.

Chemical etch technique has been successfully employed on {010} faces of solution-grown single crystals of magnesium sulphate heptahydrate (MgSO₄, 7H₂O) for the first time with greater details. Growth hillocks, macrospirals and etch channels are the main features observed and interpreted. Surface structures of the etched pits were photographed in an optical microscope. Some photographs were also recorded with a scanning electron microscope.

6 illus, 1 table, 24 ref

001061   Kansara M J;Sapna P;Subrahmanyam N B V;Bhatt J P;Singh P (Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai-400 085) : Development of a terminal voltage stabilization system for the FOTIA at BARC. Pramana J Phys 2002, 59(5), 761-4.

Terminal voltage stabilization system for the folded tandem ion accelerator (FOTIA) was developed and is in continuous use. The system achieves good voltage stabilization, eliminates ground loops and noise interference. It incorporates a correcting circuit for compensating the mains frequency variations in the GVM amplifier circuit. The present system has two modes of operation namely GVM control mode and slit control mode. A voltage stability of about ±2 kV has been achieved. Some of the salient features of the voltage stabilization system are discussed.

2 illus, 6 ref

001060   Hellborg R;Hakansson K;Faarinen M;Kiisk M; Persson P;Skog G;Stenstrom K (Dep Physics, Lund University, Solvegatan-14, SE-223 62 Lund, Sweden) : Mechanical design of the recirculating, terminal pumping in the Lund pelletron, and experimental experience. Pramana J Phys 2002, 59(5), 725-37.

Recirculating terminal pumping system has been installed in the 3 MV Pelletron tandem accelerator in Lund. An extremly limited space in the high voltage terminal and the absence of electrical power in the terminal, forced us to provide a unique design for the installation and powering of the new pumps. Details of the technical design, as well as experience of the use of the new system for accelerator mass spectrometry, have been given.

8 illus, 1 table, 21 ref

001059   Hankare P P;Gavali L V;Chavan S S (Department of Chemistry, Shivaji University, Kolhapur-416 004) : X-ray diffraction studies of azo schiff base. Indian J Phys-Pt A 2002, 76(6), 587-9.

An X-ray diffraction study has been carrie dout for 4-[2' hydroxy salicylidene 5'-(2"-thiazolylazo)] toluene. This ligand was synthesized by condensing 5'-(2'-thiazolylazo) salicyladehyde and p-toluidine. The purified sample has been subjected for structural characterization. the structure of compound is found to be tetragonal belonging to non-primitive system. The strain broadening effects are also examined and discussed.

2 illus, 2 tables, 8 ref

001058   Haldar S C (Dep Mech Engng, Reg Engng Coll, Rourkela-769 008) : Buoyancy effects on fully developed forced flow through horizontal rod-bundles. J Energy Heat Mass Transfer 2001, 23(1), 87-99.

Numerical solution of combined convection has been carried out in horizontal concentric annulus the core of which represents a rod of a rod-bundle assembly and the annular space around it was assumed to be the zone of thermal-hydraulic influence of this rod. At lower Gr, the prescribed uniform heat flux condition on the rod surface maintains a uniform temperature too. With increasing buoyancy, this isothermality is destroyed and the rod temperature gradually increases from the bottom to the top. Buoyancy increases Nu quite significantly for Grashof number based on hydraulic diameter more then 10⁴ while the increase in fRe is marginal. The single cell flow structure at low Gr changes to a multicellular one at higher Gr.

8 illus, 14 ref

001057   Ghosh S et al (Nuclear Science Centre, , Aruna Asaf Ali Marg, New Delhi-110 067) : First on-line test of the LINAC superbuncher at Nuclear science centre. Pramana J Phys 2002, 59(5), 881-4.

An on-line test of the LINAC superbuncher at Nuclear Science Centre has been successfully performed. DC O⁷⁺ beam of nominal energy 92 MeV was accelerated through the superbuncher resonator, operating at a field of 4.54 MV/m. The total energy gain of the beam was measured to be 4.5 MeV. For the pulsed beam test a phase locked bunched beam of ⁷⁺ of nominal energy 92 MeV, FWHM 1.3 ns from the pre-tandem multiharmonic buncher was injected into the superbuncher. By properly adjusting the phase and amplitude of the resonator, the best FWHM of the bunched beam was measured to be 185 ps near the entrance of the first LINAC module. Fully depleted cooled surface barrier detector was used for measuring the time width. In a separate experiment the intrinsic time resolution of the same detector was measured to be 134 ps. Consequently, the intrinsic time width of the bunched beam, after correcting for the detector resolution, would be 127 ps. Details of the experiment and results are presented.

2 illus, 5 ref

001056   Dutta K;Karmakar A;Dutta L;Sit S K;Acharyya S (Dep Phys Raiganj Coll, University College, PO Raiganj Dist, Uttar Dinajpur-733 134) : Double relaxation phenomena of di-substituted benzenes and anilines in non-polar aprotic solvents under high frequency electric field. Indian J pure appl Phys 2002, 40(11), 801-15.

The derived linear equation for different weight freactions of di-substituted benzenes and anilines (j) in aprotic and non-polar solvents. Under 9.945 GHz electric field are obtained from the available measured dielectric relative permittivities at 35°C. The double relaxation times τ₁ and τ₂ of the flexible part and the whole molecule are estimated from the slope and intercrept of the above equation. The real and imaginary parts of the high frequency complex orientational dielectric susceptibility. Is the low frequency dielectric susceptibility, which is real. They are, however, related with the measured relative permittivities. Values to τj are calculated from the ratio of the individual slopes of the variations. Assuming single Debye-like dispersions. The weighted contributions c₁ and C₂ towards dielectric relaxations for τ1 and τ2 can be obtained from Frohlich's theoretical formulations. The latter measured values are employed to get symmetric distribution parameter γ to yield symmetric relaxation time τ_s. The dipole moments μ₁ and μ₂ for the flexible part and the whole molecule are ascertained from τ₁ and τ2. The values of μ are finally compared with the reported μ's.

8 illus, 4 tables, 28 ref

001055   Dubey R N;Qureshi M S;Singh V;Tiwari M;Dhoble S J (Department of Physics, Maulana Azad College of Technology, Bhopal-462 007) : On the paramagnetic behavior of CaS: Pr phosphors. Indian J Phys-Pt A 2002, 76(6), 591-3.

Magnetic susceptibility of CaS:Pr has been studied at room temperature (300°K) by varying the concentration of Pr from 0.004 to 0.120% by weight. Paramagnetic behavior of Pr ions is explained using tri/tetra velent state of Pr along with cluster hypothesis. This study shows that activator enters CaS lattice in trivalent state at lower concentration and in tetravalent state at higher concentration. Clustering of ions occurs at 0.02% by weight of Pr and above.

2 illus, 1 table, 19 ref

001054   Dogan A;Arslan A;Havvatoglu Y (KSU Fen-Edebiyat Fakultesi, , Fizik Bolumu-46100) : Temperature dependence of strain associated with domain walls in martensitic phase transition from fcc to fct. Indian J pure appl Phys 2002, 40(11), 775-9.

In-Tl alloy undergoes a martensitic transition from fcc to fct and is treated by a phenomenological theory based on Landau's theory of phase transitions. Analytic expressions concerning the temperature dependence of the strain associated with the domain walls observed in this type of alloys are given.

4 illus, 13 ref

001053   Dhoble S J;Nayar V;Kher R S;Chandra B P; Khokhar M S K (Kamla Nehru College, Sakkardara Square, Nagpur-440 009, Maharashtra) : Effect of lyoluminescence decay in KCl microcrystalline powder in lyoluminescence dosimetry of ionization radiations. Indian J Phys-Pt A 2002, 76(6), 577-9.

The lyoluminescent intensity of gamma irradiated potassium chloride powder of different particle sizes have been investigated. In the mesh range -75-250 μm, the lyoluminescence(LL) peak intensity increases with increasing particle size. Above 250 μm and upto 425 μm, the LL peak intensity decreases. For particle size greater than 425 μm, the LL peak intensity increases again. The LL glow curves show that LL decay times consist of two components for all particle sizes. The dependence of decay time, especially the longer component on the particle size has been investigated. Particle size has no significant effect on the shorter decay component in LL emission. A possible explanation for the experimental results has been attempted.

4 illus, 7 ref

001052   Chopra S et al (NO, Nuclear Science Centre, Post Box-10502, New Delhi) : New modifications in 15 UD pelletron at Nuclear Science Centre. Pramana J Phys 2002, 59(5), 753-9.

The 15 UD pelletron at NSC has been operational and performed well during the last 11 years. There have been major modifications performed for upgradation of pelletron system over this period. Major upgradations which have been implemented are new resistor network system for voltage gradient, doublet to singlet unit conversion for accelerator units, turbopump based gas stripper system etc., In addition, accelerator mass spectroscopy program has also been started. A new multi-cathode source, Wien filter etc. have been procured and will be added soon in the system. An overview of the most significant upgradations undertaken and other activities for the system are being reported.

7 illus, 1 table, 4 ref

001051   Chandrasekar M (Sch Math, Anna Univ, Chennai-600 025) : Non equilibrium thermodynamics. J Energy Heat Mass Transfer 2001, 23(1), 101-16.

The variational principle developed by Gyarmati embodying the principles of non-equilibrium thermodynamics is employed to study the effects of suction and injection in laminar boundary layer flow and heat transfer over a semi-infinite flat plate. The velocity and temperature fields inside the boundary layer are approximated by simple polynomial functions and the functional of the variational principle is constructed. The hydrodynamical and thermal boundary layer thicknesses are derived as the Euler-Lagrange equations of the variational principles. The obtained skin friction and heat transfer values were computed for various values of suction and injection parameter and the Prandtl number. Analytical solution for various values of H is compared with the available approximate and numerical solution and are found to be in good agreement with the numerical results and the accuracy is remarkable for the case H=O.

2 illus, 5 table, 12 ref

001050   Chakrabarti C G;De M K (Department of Applied Mathematics, University of Calcutta, Kolkata-700 009) : Statistics of closed multi-component system : entropy, fluctuation and stability. Indian J Phys-Pt A 2002, 76(6), 573-6.

Deals with the derivation of the probability distribution of a closed multi-component system, the expression of entropy-production for chemical reaction, the criterion of chemical stability and the generalized Le-Chatelier-Braun principle of chemical equilibrium on the basis of a probabilistic model of the closed multi-component system.

10 ref

001049   Bhalekar A A (Dep of Chem, Nagpur University, Amravati Raod Campus, Nagpur-440 010) : Irreversible thermodynamic framework using compatible equations from thermodynamics and fluid dynamics a second route to generalized phenomenological irreversible thermodynamic theory (GPITT). Bull Calcutta Mathl Soc 2002, 94(3), 209-24.

How to develop an irreversible thermodynamic framework both for spatially uniform and non-uniform systems have been addresed. That every irreversibility has its chemical interaction component which is needed to be quantified through the Gibbs function. This has been revealed by systematic handling of Clausius' inequality to arrive at the entropy function for nonequilibrium and then coupling it with the "universe of operations" of thermodynamics. It has become apparent that the internal thermodynamic states have to be identified. This is a finer aspect of chemical interactions. The mass fractions of these populations and the corresponding chemical potentials determine the type and extent of irreversibility due to the existence of spatial non-uniformity. These pairs of thermodynamic parameters can be taken as the ones conjectured by bridgman for nonequilibrium.

24 ref

001048   Bhalekar A A (Dep of Chem, Nagpur Univ, Amravati Road Campus, Nagpur-440 010) : Fluid dynamical conservation equations of internal energy and matter for spatially non-uniform systems vis-A-vis the local equilibrium assumption of irreversible thermodynamics. Bull Calcutta Mathl Soc 2002, 94(3), 185-96.

The much celebrated local equilibrium assumption (LEA) of classical irreversible thermodynamics (CIT) have been criticised pointing out that it does not conform to the dictates of the second law of thermodynamics. The dictates of the second law of thermodynamics and Eddington's law of Nature (1931) unambiguously establish that the so-called LEA is an ill conceived proposition and hence it led irreversible thermodynamics to the troubled waters, as is amply evident from the contemporary thermodynamic literature. It has been proved herein that the traditional Gibbs relation even at the local level remains valid only for the spatially uniform systems nonetheless it adequately describes irreversibility originating from the finite rates of chemical conversions irrespective of whether the system happens to be close to or far away from equilibrium.

64 ref

001047   Bhagwat P V (Nuclear Physics Division, BARC-TIFR Pelletron Accelerator Facility, , Mumbai-400 005) : Improvement in performance and operational experience of 14 UD pelletron accelerator facility, BARC-TIFR. Pramana J Phys 2002, 59(5), 719-24.

14 UD Pelletron Accelerator Facility at Mumbai has been operational since 1989. The project MEHIA (medium energy heavy ion accelerator) started in 1982 and was formally inaugurated on 30th December 1988. Since then the accelerator has been working round the clock. Improvement in accelerator performance and operational experience are described.

5 illus, 1 table

001046   Bansod V J (Fac Math, Dr B A Technol Univ, Lonere-402 103) : Boundary layer solution of convective heat and mass transfer from a horizontal surface in a non-darcy porous media. J Energy Heat Mass Transfer 2001, 23(4), 379-91.

The non-Darcy natural convection heat and mass transfer near a horizontal impermeable surface embedded in a fluid-saturated porous medium has been analysed. A similarity solution is presented in the boundary layer region for the case of constant surface heat and mass fluxes at the wall. The structure of flow, temperature and concentration fields are governed by the parameters like the buoyancy ratio, Lewis number and the flow controlling parameter. The effect of these parameters on the non-dimensional heat and mass transfer coefficients are presented and it is found that the interial effects reduce the heat and mass transfer coefficients.

6 illus, 20 ref

001045   Ashok Kumar;Naithani U C;Semwal B S (Dep Phy, Garhwal Univ, Pauri Campus, Pauri (Garhwal)) : Study of Ba_x Sr_1-x TiO₃ mixed system. Indian J pure appl Phys 2002, 40(11), 831-4.

Pellets of Ba_xSR_1-x TiO₃ using solid solution reaction method have been prepared. The prepared samples have been characterized using X-ray diffraction method and grain size have been found using SEM photographs. The loss tangent of these materials has been measured in para-electric phase. The temperature, frequency and concentration dependences of dielectric properties have been studied. Apart from experimental study on Ba_xSr_1-xTiO₃, the parameters α,β,γ by using the empirical formula [(T-T_c) tanδ=ω(α+<98>T+γT²)] for different values of x in ba_xSr_1-xTiO₃ have been calculated. The results have been compared with the previous experimental and theoretical results.

1 table, 35 ref

001044   Ashenfelter J (Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut, USA) : Operational performance of the Yale ESTU. Pramana J Phys 2002, 59(5), 713-7.

The ESTU began operation in 1988 and achieved the design voltage of 20 MV in 1990. Since that time, improvements to the gas handling system, negative ion injector, accelerator terminal and control system have greatly increased its capability and reliability. Today, the ESTU can efficiently produce an extensive assortment of stable ions at wide-ranging energies in support of low-energy nuclear physics.

2 illus, 1 table, 9 ref

001043   Abou El-Ela (Department of Physics, Ain Shams University, Heliopolis, Cairo, Egypt) : Transient hot electron transport properties in ZnS:Mn. Indian J Phys-Pt A 2002, 76(6), 581-5.

The time dependence of transport properties of ZnS:Mn such as the total average electron velocity, the total average energy, the total average electron temperature and the average fraction number in central valley (Γ-valley) have been calculated for uniform electeric fields. These calculations were used to determine the electron scattering mechamisms responsible for hot electron transient behaviour in ZnS;Mn at very high electric fields. In these calculations, the Monte Caro method at the lattice temperature of 77 and 300 K were used. The results showed that the steady state conditions were reached within 0.5 pico second or less depending on the strength of the electric field and the lattice temperature. The essential feature of time transport is the overshoot behaviour owing to the intervalley phonons scattering.

7 illus, 23 ref

000209   Verma A L;Thanga H H;Kitagawa T (Dep Physics, North-Eastern Hill University, NEHU Campus, Shillong-793 022) : Excitation wavelength dependence of photoreduction of cytochrome c and its mechanism monitored by resonance Raman spectroscopy. Asian J Spectrosc 2001, 5(3), 97-111.

Purified monomeric cytochrome c (Cyt-c) at neutral pH exhibited extensive photoreduction under anaerobic conditions (a fore pressure of 10^-5 Torr) upon laser irradiation in the 400-450 nm region and the resonance Raman (RR) spectrum of the photoreduced species was identical with that of the chemically reduced species. However, only partial photoreduction occurred at pH 10.1 where the axial methionine ligand is replaced probably by lysine, and no photoreduction took place after the transitions with pK_a = 12.76 and 2.5 where the axial histidine ligand is replaced by other residue. The photoreduction was completely inhibited in the presence of oxygen suggesting active participation of a triplet state in this process. The relative quantum yield for photoreduction of Cyt-c at neutral pH as a function of excitation wavelengths shows a weak maximum centered around 410 nm while it increases almost exponentially when excitation wavelength is moved from 380 to 330 nm and then tends to saturate from 330 to 260 nm. Immediate electron donors to the heme and plausible mechanisms of the photoreduction are discussed. Also investigates the effects laser power, salt and buffer concentration on the yield of photoreduction.

28 ref

000208   Venkata Ramana G;Rajagopal E;Manohara Murthy N (Physics Dep, Srikrishnadevaraya Univ, Anantapur-515003) : Effect of ammonium halides on the temperature of sound velocity maxium of water. Indian J pure appl Phys 2002, 40(10), 683-9.

Effect of ammonium halides on the temperature of sound velocity maximum (TSVM) of water has been studied by determining the ultrasonic velocity with an accuracy of ±0.003% using single-crystal variable-path interferometer working at 3 MHz. The velocity measurements were carried out at ≅2°C intervals over a range of 5°C to either side of the TSVM of the solutions. The accuracy in fixing the TSVM is ±0.2°C. The shift in TSVM of water due to the addition of the solute. The shifts in TSVM of water due to the addition of the NH₄CI, ΔT_obs, is found to be positive up to w≅3.4x10^-2 and negative thereafter, where w represents weight franction of the solute. The shifts in TSVM of water due to the addition of the NH₄Br is almost zero up to w≅ 3x10^-2 and thereafter become negative. ΔT_str for NH₄I is found to be negative throughout the concentration range. The results are explained in terms of the structure, making and breaking nature of anions and cations present in the solutions.

6 illus, 1 table, 27 ref

000207   Upreti U C;Narlikar A V (NO, Nat Phys Lab, Dr K S Krishnan Road, New Delhi-110 012) : Low concentration dopant disorder modified carrier scattering and related correlations in YBCO. Indian J pure appl Phys 2002, 40(9), 637-42.

The possible carrier scattering modifications and the related correlations due to low concentration planar and chain site, Zn and Fe, dopings in YBCO thin films have been explored. Zn seems to lower T_c as well as resistivity up to about 300 K whereas Fe raises the mean field T_c slightly but enhances the resistivity remarkably. The resistivity behaviour, site selectivity effect on resistivity and coherence length, and the interaction effects in resistivity and coherence data have been presented. Indicates strong interplay between impurity effects and carrier-carrier scattering. The inverse variation of T_c with coherence length ξ and the T_c degradation and ξ enhancement seem to be due to change of the carrier-carrier scattering by impurity not by the direct carrier-impurity scattering.

30 ref

000206   Upadhyay T C;Semwal B S (Phys Dep, HNB Garhwal Univ, Srinagar (Garhwal), Uttaranchal-246 174) : Temperature dependence of dielectric tangent loss in KDP and DKDP crystals at microwave frequencies. Indian J pure appl Phys 2002, 40(9), 615-9.

By adding cubic and quartic phonon anharmonic interactions in the pseudospin phonon coupled mode (PLCM) model for KDP type crystals and using double-time temperature-dependent Green's function method, expressions for soft mode frequency, dielectric constant and dielectric tangent loss have been obtained. Using model parameters, the dielectric losses are calculated for KDP and DKDP crystals. In the microwave frequency range, an increase in frequency is followed by an increase in dielectric tangent loss. The loss decreases with increase in temperatures for KDP and DKDP crystals, respectively, in their para-electric phase. This shows Curie-Weiss behaviour of the dielectric tangent loss.

4 illus, 23 ref

000205   Thakur M L;Sharma K S (PG Dept of Physics, T M Bhagalpur University, Bhagalpur) : Test of values of parameter of L-J (m, n) potential models and laws of intermolecular forces for second virial coefficient and viscosity of gases He, Ne and Ar. Acta Cienc Indica-Phys 2002, 28(1), 19-26.

3 illus, 6 tables, 18 ref

000204   Sinha S N (Dept of Physics, R K Dwarika College, Patna) : MRINDO/s calculation on the electronic spectra of ethylene oxide and acetic acid. Acta Cienc Indica-Phys 2002, 28(1), 11-14.

MRINDO/S method was applied on ethylene oxide and acetic acid to account for their electronic spectra. The importance of output (Rydberg) atomic orbitals is stressed and it is found that some of the transitions lead to excited state with considerable Rydberg character. The ionization potentials of the molecular series are also interpreted.

3 tables, 10 ref

000203   Singh A K;Manindra Kumar;Kumar S K (Dept of Physics, C M Sciences College, Darbhanga) : Electronic conduction in disordered and non-crystalline medium. Acta Cienc Indica-Phys 2002, 28(1), 27-30.

Considering scattering of electrons by a random distribution of centres a conductivity formula for metallic impurity conduction is obtained. Ziman's weak scattering theory is used in which scattering by each centre is considered small and the mean free path L is consequently large (KL >> I). This formula is applied in calculating resistivity of heavily doped semiconductor e.g., n-type germanium and the results obtained thus are found in fair agreement with experimental values.

8 ref

000202   Singh A K (Mathematics Dep, VSSD Coll, Kanpur-208002) : MHD free convective flow through a porous medium between two vertical parallel plates. Indian J pure appl Phys 2002, 40(10), 709-13.

Free convective flow of a viscous, incompressible, electrically conducting fluid through a porous medium between two vertical parallel plates which are heated or cooled uniformly, under a pressure gradient in presence of uniform transverse magnetic field has been studied. The governing equations are solved to obtain approximate analytical solutions for velocity field and temperature distribution for small values of Rayleigh number, usign regular perturbation technique. Two physical situations, namely, steady heating of ascending cold fluid (SHACF) and steady cooling of ascending hot fluid (SCAHF) have been investigated. The effect of various parameters on velocity field, temperature distribution, mass flow rate ratio, friction factor ratio and heat transfer rate has been discussed.

6 tables, 14 ref

000201   Sikka S K;Roy F;Basu T K (Seismology Div, Bhabha Atomic Research Centre, Mumbai-400 085) : Body-wave magnitude bias between Pokhran and eastern Kazakh nuclear test sites. Curr Sci 2002, 83(8), 992-7.

For estimating the yield of the Indian nuclear explosions of 11 May 1998 (POK2), some seismologists have used the parameters of Shagan River test site (SRTS) eastern Kazakh as a representative for Pokhran test site, and have underestimated the yield of POK2. Shown that there is a body-wave magnitude bias of <126>0.4 units between the SRTS and the Pokhran site. It would be necessary to take this bias into account before estimating the yield of POK2 using a yield-magnitude relation that is applicable to the SRTS alone.

4 illus, 2 tables, 22 ref

000200   Sharma A (Directorate of Education, Community Science Centre, Post Box 107, Shimla-171 001) : Einstein's inconsistent light energy-inertia (mass) equation <128><68>m=L/C<. Acta Cienc Indica-Phys 2002, 28(1), 35-40.

1 table, 5 ref

000199   Sardana H K;Julka G;Chhabra j K (Cen Scien Instrum Org, , Sector-30, Chandigarh-160030) : Integrating communication with sensing micro-bending of multi-mode optical fibre. Indian J pure appl Phys 2002, 40(10), 720-5.

Environmental perturbations on a multi-mode fibre lead to changes in intensity at the output due to bending induced losses. A carrier signal has been modulated in a form such that, the amplitude of the light signal is not affected, which is left for sensing light intensity variations due to micro-bending. Pulse frequency modulation has been suggested for this purpose using a voltage-to-frequency converter. This information is again decoded at the receiver end using frequency-to-voltage conversion. A fibre link, which is acting as a perturbation sensor, also acts as a communication link without affecting the sensing capability as long as the link is not damaged due to perturbation. It is known that, the multi-mode fibre can be used to sense any form of environment perturbation, such as strain, pressure, force, position, acceleration, temperature etc^1-3. The proposed approach is applicable in all these situations with integrated communication capability.

2 illus, 1 table, 11 ref

000198   Roy V K (University Department of Physics, L N Mithila University, Darbhanga-846 004) : Theoretical study of the effects of multipath on antenna time delays. Acta Cienc Indica-Phys 2002, 28(1), 1-6.

An analytical expression is presented for calculating the effects of multipath on antenna time delays. These discoveries led to the eventual development of new "translator-calibration technique", which has been and is still being used to calibrate ground-station delays, as part of the process of determining the range to a spacecraft. Theoretical curve shows plots of the upper and lower bounds of the groups delay in a free-space medium. The upper bound is obtained when the leakage and primary waves are in phase whereas in the lower bound they are out of phase.

2 illus, 9 ref

000197   Roy S;Singh C P;Reddy K P J (Physics and Computer Science Dep, Dayalbagh Educational Institute, Agra-282 005) : Analysis of all-optical switching in bacteriorhodopsin. Curr Sci 2002, 83(5), 623-7.

All optical switching has been demonstrated in bacteriorhodopsin (bR) based on nonlinear, intensity-induced excited state absorption. The transmission of a cw probe laser beam at 640 nm corresponding to the peak absorption of O-state through a bR film is switched by a pulsed pump laser beam at 570 nm that corresponds to the maximum initial B-state absorption. The switching characteristics have been analysed using the rate equation approach and the six intermediate states in the bR photocycle. The effect of various parameters such as pump pulse width and intensity, rate constants of M and O states and absorption cross-section of the B-state at probe wavelength on switching, have been analysed in detail. It has been shown that the probe laser beam can be completely switched off by the pump laser beam at relatively low pump powers, if the B-state does not absorb the probe beam.

5 illus, 21 ref

000196   Rao P K;Dodd D S;Virender Singh (Cen Scient Instrum Organ, , Sector 30, Chandigarh-160 030) : Night driving filter for automobiles. Indian J pure appl Phys 2002, 40(9), 611-4.

The dazzle (excessive visible radiation) produced by the headlights of the oncoming vehicles, blinds the driver's eyes instantly, during night driving. The frequent dazzling not only makes the driving difficult but, it also impairs the vision. Therefore, it is essentially required to suppress the dazzle by means of an optical filter. The night driving filter absorbs the excessive radiations resulting in reducing the glare. The night driving filter consists of a vacuum deposited gradient density, neutral film, having a required thickness gradation profile on a glass substrate. Online testing of filter was done, by fitting it in the car and driving on light and un-lighted roads, single and dual carriage-ways. The results show that the right hand portion of the filter blocks the glare and reduces it to about 25-30 percent. View of the road from the center as well as from left hand portion of the filter, is not reduced.

2 illus, 1 table, 7 ref

000195   Prabhavathi T;Sridharbabu Y;Quamara J K (Appl Phys Dep, Regional Engng Coll, Kurukshetra-136 119) : Dielectric relaxation studies of 100 MeV Ni<. Indian J pure appl Phys 2002, 40(9), 645-9.

Kapton-H polyimide samples of thickness 12.5 μm have been irradiated with 100 MeV Ni⁵⁸ ion beam with fluences 6.295 x 10¹¹ and 2.57 x 10¹² ions/cm². The dielectric constant/loss investigations have been measured from 30 to 240 °C for different frequencies ranging from 100 Hz to 3 MHz. The nature of ε^'-T curve in low temperature region (30-70 °C) is mainly governed by γ-relaxation. The dielectric loss peak at 60 °C is in conformity with this relaxation. The dielectric constant in the temperature range 70-180 °C is mainly governed by dipolar and space charge relaxations. The new energy traps due to the formation of free radicals by high-energy ion irradiation, contributes significantly towards space charge relaxation. In that temperature region, ε^' of high flux irradiated samples is more than low flux irradiated samples. In high temperature region (180-240 °C) the increase in ε^' with temperature is mainly due to interfacial polarization, which arises due to formation of new phases by irradiation. The loss maximum in ε^"-T curve at 240 °C confirms the presence of this relaxation.

2 illus, 14 ref

000194   Paul I;Varghese G;Ittyachen M A (Sch Pure Appl Phys, Mahatma Gandhi University, Kottayam, Kerala-686 560) : Thermal decomposition studies of struvites. Indian J pure appl Phys 2002, 40(9), 664-9.

Ammonium magnesium phosphate hexahydrate crystals (struvites) were grown using silica gel technique by the controlled reaction method. The grown crystals were characterized using X-ray powder diffraction. Thermal analysis of these crystals was studied in the temperature range 30-1000 °C in argon atmosphere. A two-stage decomposition occurs. Corresponding activation energies are determined using Coats-Redfern method.

4 illus, 2 tables, 14 ref

000193   Okunade A A ;Ogundare F O;Hussain L A (Dep Phys, Obafemi Awolowo Univ, Ile-Ife, Osun State Nigeria) : Analytical models for the angular distributions of filter-generated scatter in diagnostic radiology. Indian J pure appl Phys 2002, 40(10), 732-42.

Analytical models for describing large volume of data on angular distributions of photons that have undergone Compton & Rayleigh interactions while passing through spectrally equivalent filter materials commonly considered useful in diagnostic radiology have been developed. The comparison of the results of simulation of scatter data from these filter materials, using Monte Carlo techniques with those from the models developed, are in reasonable agreement.

5 illus, 6 table, 15 ref

000192   Mishra M C (Dept of Physics, M L Academy, Laheriasarai, Darbhanga) : Analysis of radar backscatter cross section from clouds. Acta Cienc Indica-Phys 2002, 28(1), 7-10.

Analyses reflections of Gigahertz Frequency Radar Singals from typical clouds over Bihar. Four principal mechanisms of reflection are identified. While the backscatter cross sections for these are mostly well known, there is a need to identify which, if any, are dominant in each frequency range. Numerical studies of superpositions of the main back scatter mechanisms are presented.

2 illus, 14 ref