007213   Jain M;Kundu N (Radio & Atmospheric Science Division, National Physical Laboratory, New Delhi 110 012) : Effect of volcanic aerosols on stratospheric ozone at Kodaikanal. Indian J Radio Space Phys 2004, 33(3), 170-5.

Nimbus 7 SBUV data (average of zonal means for 5-10°N) and Dobson data over Kodaikanal (10° N latitude) for the period 1979-1994 have been analysed to study the effect of El-Chichon and Pinatubo volcanic eruptions on ozone quasi-biennial oscillation (QBO). The ozone QBO has been found to be disturbed up to the height of 34 km following both the eruptions and the effect persisted even after one year of the event. The impact of El-Chichon volcanic eruption on ozone shows a depletion up to 34 km with maximum effect at 29 km, whereas the impact following Pinatubo eruption shows ozone depletion up to 29 km above which an increase in ozone is observed. The cause of depletion below about 27 km is due to well known heterogeneous chemistry. The cause of ozone depleion above 27 km following the two major eruptions has been investigated. The percentage change in ozone has been estimated after taking the warming due to aerosol into consideration. The theoretically calculated and the observed percentage deviations of ozone show good agreement in the case of El-Chichon eruption, while for Pinatubo eruption the calculated values show more negative values.

007212   Jagjiwanram;Ramvir Singh (Thermal Phys Lab, Phys Dep, Univ of Rajasthan, Jaipur-302 004) : Effective thermal conductivity of two-phase systems with cylindrical inclusions. Indian J pure appl Phys 2004, 42(8), 600-609.

A theoretical model is presented to predict effective thermal conductivity of real two-phase materials from the values of thermal conductivity of the constituent phases and their volume fractions. Two-phase materials have been assumed to contain cylindrical particles agganged in a regular three-dimensional cubic geometry. The arrangement has been divided into unit cells, each of which contains a cylinder. The resistor model has been applied to determine the effective thermal conductivity (ETC) of the unit cell. A porosity correction term F is introduced in order to incorporate varying individual geometries and non linear flow of heat flux lines generated by the difference in thermal conductivities of constituent phases. Theoretical calculations of the ETC have been carried out on a large number of samples and comparison have been made with other models and experimental values cited in the literature. The values predicted by the proposed model are in close agreement with experimental values and more accurate than those obtained from existing models.

6 illus, 1 table, 31 ref

007211   Havvayi P (Department of Physics, University of Tabriz, Tabriz (Iran)) : Linear irreversible thermodynamics and the two-fluid model of superfluid helium. Ultra Scient phys Sci 2003, 15(3), 355-62.

The general theory of linear irreversible thermodynamics has been adopted to the two-fluid model of superfluid helium. In this model He-II is considered as a system of two-components mixture, each with its own density, and to a first approximation, its own independent velocity field. In contrast to the earlier works, the model assumes that superfluid contains small amountof entropy (Σ_s≠0), owing to the fliessbach. Hence, starting from the basic conservation relations for the two-components mixture, the entropy flux and entropy Production rate is introduced. Since, the matrix elements (L_ij) appearing in the flux-force equations contain observable quantities of the system, explained the way of determining these coeficients. Using the experimental data's of Previous workers, the numerical values of Onsager;s coefficients for superfluid He-II have been evaluated.

1 illus, 21 ref

007210   Gunasekaran S;Rajkumar R (Post-Graduate and Research Department of Physics, Pachaiyappa's College, Chennai-600 030) : Internal standard calculations and quality factor determination of coconut oil. Acta Cienc Indica-Phys 2004, 30(2), 143-54.

Coconut oil is one of the many oils used by as such. Ayurvedic oils meant for massaging purposes and external application contain invariably coconut oil as one of the ingredients. Believed to be a foaming agent, coconut oil is mixed as an ingredient in bath soaps. Lauric acid, a major constituent of coconut oil, has been found to possess tremendous anti-cancer, anti-viral and anti-microbial properties, which in turn renders coconut oil as an anti-cancer, anti-viral and anti-microbial agent. A new school of thought has emerged which advocates the use of coconut oil and lipids as inactivating agent for treating HIV positive individuals. The recent research and published documents prove beyond doubt that coconut oil has beneficiary effect rather than harmful ones on human beings. Application of IR spectroscopy to determine the purity of coconut oil samples collected from different sources has been presented. The frequency assignments of the IR bands of coconut oil were made and the internal standards ratio of the specific modes of the vibration were also calculated. The frequency assignments for the IR bands of lauric acid and comparison of the spectra of lauric acid and coconut oil were also made.

5 illus, 11 tables, 31 ref

007209   Ghosh S;Pande K N;Wankhade Y D (Phys Dep, Govt. Vidarbha Inst of Sci and Humanities, Amravati) : Theoretical ultrasonic velocities in binary liquid mixtures using scaled particle theory. Indian J pure appl Phys 2004, 42(10), 729-34.

Ultrasonic velocity and density have been measured in binary liquid mixtures of 1,1,1-trichloroethane with 1-alkanols at 303K. Shapes of constituent molecules are considered as spherical, cubical and tetrahedral with the application of scaled particle theory. Theoretical velocities have been compared with observed velocities for each shape combination. An attempt has been made to predict the behavioural shape of 1,1,1-trichloroethane, 1-propanol, 1-butanol, 1-pentanol and 1-hexanol.

3 tables, 9 ref

007208   Ghosh S;Nambissan P M G;Bhattacharya R (Phys Dep, Univ of Calcutta, 92 A.P.C. Road, Kolkata-700 009, ) : In<. Physica B 2004, 353(1-2), 75-81.

007207   Engles D;Malik S S (Electronics Technol Dep, Phys Dep, Guru Nanak Dev Univ, Amritsar-143 005) : Analysis of coupling characteristics of rectangular core optical waveguide coupler. Indian J pure appl Phys 2004, 42(9), 674-83.

A theoretical formulism based on the boundary matching technique has been proposed to study the systematic of an asymmetric waveguide coupler. Same formulism is applicable to a symmetric coupler. The equivalent parallel coupling length to account for the coupling in the two S-shaped regions in the input and the output of the coupler is obtained from the coupler geometry and is dealt with more accurately and sensitively in calculations. No fitting parameter is required for calculation. The calculated characteristics of the asymmetric coupler are very close to those of experimental ones. This model can aid in the design of diffused channel single mode rectangular core optical waveguide couplers.

9 illus, 11 ref

007206   Chate D M;Rao P S P;Momin G A;Safai P D;Ali K;Tiwari S;Praveen P S (Indian Institute of Tropical Meterology, , Pune 411 008) : Variations in the concentrations of ionic species in rain events at Pune. Indian J Radio Space Phys 2004, 33(3), 185-8.

Evolutions of the concentrationsof major neutralizing agents (Ca²⁺ and NH₄^{+) and acidic species (SO₄2 and NO₃) are computed with Slinn's model using the initial number concentrationso f particle size distributions measured at Pune during 1998-1999. Theoretically predicated ionic concentrations are compared with observed ionic concentrations in the sequential samples collected in the rain events at Pune. Also, equivalent ratios {(SO₄2 + NO₃)/(Ca2+ + NH₄+) are computed theoretically to study the neutralizing capacity of the atmosphere during precipitation events and compared them with observed ones. The variation of observed equivalent ratios with accumulated rain (mm) indicated that acidic components are always neutralized with neutralizing species.}

4 illus, 13 ref

007205   Charan R V K;Singh S N (Department of Physics, Gaya College, Gaya) : Rindo/s-CI calculation for electronic spectra of furazan & its mono-methyl derivative. Acta Cienc Indica-Phys 2004, 30(2), 163-8.

A study of the electronic spectra of five membered ring compound-Furanzan & its mono-methyl derivative has been done with the calculation of their ionisation potential, excitation & splitting energies, singlet-singlet & singlet-triplet transitions by RINDO/S-CI method and their results have been expressed in terms of valence & Rydberg excitations along with their corresponding experimental values.

6 tables, 12 ref

007204   Calla O P N;Ranjan V;Bohra C;Naik G L;Waseem Hasan;Bali H S (International Centre for Radio Science, , OM-NIWAS" A-23, Shastri Nagar, Jodhpur 342 003, Rajasthan) : Estimation of dielectric constant of soil from the given texture at microwave frequency. Indian J Radio Space Phys 2004, 33(3), 196-200.

Value of the dielectric constant of a given sample of soil has been estimated from its known texture by multiplying the given texture with the constants at different microwave frequencies. The model is tested for four samples of soil: one sample from Uttar Pradesh and three samples from Kashmir in India.

2 illus, 11 tables, 6 ref

007203   Batal F H A;Nada N;Desouky S M;Khalil M M I (Glass Res Dep, National Res Center, Dokki, Cairo, Egypt) : Absorption and infrared spectra of gamma irradiated ternary silicate glasses containing cobalt. Indian J pure appl Phys 2004, 42(10), 711-21.

Optical and infrared absorption spectra of undoped ternary silicate and CoO doped glasses were measured before and after successive gamma ray irradiation. The results obtained revealed the existence of cobalt ions mainly in tetrahedral coordination in such host glasses. The radiation-induced defects created by gamma irradiation are related to intrinsic effect of the glass constituents and extrinsic effect due to the cobalt ions. The response of the glass to irradiation and the growth rate of colour center formation are related to the equilibrium between the formation and annihilation processes of induced colour centers and the saturation or equilibrium state reached by successive irradiation.

12 illus, 2 tables, 34 ref

007202   Banerjee T;Wanchoo S K;Pai S P; Neumann-Spallart M;Narsale A M;Pinto R (SMI, MESA + Res Inst, , P O Box 217, 7500AE, Enschede, The Netherlands) : Self-injection length of polarized spins in La_0.7Ca_0.3MnO₃-YBa₂Cu₃O7-δ ferromagnet-superconductor heterostructures. Indian J pure appl Phys 2004, 42(10), 764-70.

Studies on the self-injection length of polarized spins in La_0.7Ca_0.3MnO₃ (LCMO)-YBa₂Cu₃O_7-δ (YBCO) heterostructures on LaAlO₃ (LAO) substrates fabricated in situ with pulsed laser deposition have been carried out. The measured curitical current density, J_c of YBCO microbridges on LAO (control) arm was found to be larger than that of the microbridges on the LCMO arm. the dirrerence in J_c in the two arms indicates that a certain thickness of YBCO has become effectively normal due to self-injection of spin-polarized carriers. Further, measuring transition temperature T_c of YBCO layers with ac susceptibility, it has been found that the thickness of the non-superconducting YBCO layer, due to self-injection at the interface, depends upon the LCMO thickness. Both the above experients led us to estimate the maximum thickness of the non-superconducting YBCO layer at the interface due to self injection of spin polarized quasiparticles from YBCO into LCMO; this thickness is found to be in the range 650-850 Å for LCMO thickness ≥ 1000 Å. A control experiment performed on YBCO-LNO (LaNiO₃) heterostructure did not show any evidence of self-injection.

5 illus, 1 table, 15 ref

007201   Ayodo Y K;Khanna K M;Sakwa T W (Phys Sci Dep, Western Univ Coll, Box 190, Kakamega, Kenya) : Micro-canonical ensemble model of particles obeying bose-einstein and fermi-dirace statistics. Indian J pure appl Phys 2004, 42(10), 749-57.

A micro-canonical ensemble for an assembly of bosons and fermions is considered in which the number of particles, internal energy and volume are kept constant. A statistical distribution model, which is fermion dominated and where bosons and fermions interact in pairs, is developed. The partition function is derived. Macroscopic thermodynamic quantities such as entropy, internal energy and specific heat are obtained in terms of the partition function. The model equations are applied to a mixture of liquid helium-3 and liquid helium-4 atoms.

4 illus, 5 tables, 11 ref

007200   Ali A;Anil Kumar Nain;Sharma V K;Ahmad S (Chem Dep, Jamia Millia Islamia (Central Univ), Jamia Nagar, New Delhi-110 025) : Molecular interactions in binary mixtures of tetrahydrofuran with alkanols (C₆, C₈, C₁₀): an ultrasonic and volumetric study. Indian J pure appl Phys 2004, 42(9), 666-73.

The densities and ultrasonic speeds in binary mixtures of tetrahydrofuran (THF) with alkanols (1-hexanol, 1-octanol and 1-decanol) have been measured over the whole composition range at 35°C. Isentropic compressibility, intermolecular free length, relative association, molecular association, acoustic impedance, excess compressibility, excess molar volume, excess acoustic impedance and excess partial molar volume of alkanols in THF were calculated using the values of density and untrasonic speed. The variation of these parameters with composition indicates that the disruption of associated structures of alkanols on addition of THF dominates over that of weak interaction between unlike molecules in all the three systems investigated. Moreover, a comparison of theoretical ultrasonic speeds, calculated by using collision factor theory (CFT), free length theory (FLT), Nomoto's empirical relation and Van Dael-Vangeel's ideal mixing relation, with those obtained experimentally reveals that CFT, FLT and Nomoto's relation predict the data well than ideal mixing relation.

3 illus, 4 tables, 32 ref

007199   Alam N;Pandey A K (Department of Physics, G D College, Begusarai, L N M Univ Darbhanga, Bihar) : Theory of cohesive energy of binary liquid alloys at different concentrations. Acta Cienc Indica-Phys 2004, 30(2), 191-4.

A simplified but accurate theory of the cohesive energy of metals has been developed from the density functional formulism of Kohn-Sham. In their theory the total energy of both the free atom and the solid is expressed as a sum of a core and valence binding energy is reduced to a difference in binding energies. The free-atom binding energy is directly calculated which matches the experimental energy in metals. The binding energy of liquid binary alloys is obtained by the generalized Pseudo potential method. The calculated cohesive energy agree well with experimental result. More important is that, this method permits the physical origin of cohesion to identify in all non-transition metals. It is important that band-structure effects are important in non-alkali metals.

3 tables, 13 ref

006259   Tyagi M S;Sharma A;Dwivedi H K (Central Electronics Engineering Research Institute (CEERI), , Pilani 333 031, Rajasthan) : Development of low gas pressure hollow cathode up to 3kA peak pulsed current capability. Bull Indian Vacuum Soc 2003, 6(4), 19-23.

Cold hollow cathodes have the capability to provide high current density electron emission in gaseous atmosphere. In recent years, it has been used in plasma switches for conduction of kilo amperes of current. Another type of hollow cathodes, which are thermionic emitter based, have been in use in high power Thyratron switches. In the present work oxide coated cathode based hollow cathodes have been fabricated. These cathodes have been used for the development of prototypes of hydrogen/ deuterium Thyratrons operating at gas pressure 0.5-0.8 mbar. The cathodes have first been tested in demountable diodes for evaluation of discharge current characteristics under varying gas pressure. The peak current ratings of these cathodes can be extended depending upon pulse width, pulse repetition requirements and associated thermionic cathode type. The fabrication schedule of these cathodes involves empirical design, assembly, vacuum processing, activation and processing under gaseous atmosphere. The paper discusses the main features of the processes involved and results.

5 illus, 4 ref

006258   Singh M;Vijay Y K (Phys Dep, Univ of Rajasthan, Jaipur-302 004) : Preparation and characterization of Zn-Se bilayer thin film structure. Appl Surf Sci 2004, 239(1), 79-86.

006257   Sen S;Muthe K P;Joshi N;Gadkari S C;Gupta S K;Jagannath;Roy M;Deshpande S K;Yakhmi J V (Inter University Consortium, Mumbai Center, BARC, Mumbai 400 085) : Room temperature operating NH₃ Gas sensor based on tellurium thin film. Bull Indian Vacuum Soc 2003, 6(4), 3-7.

Tellurium thin films were studied for use as ammonia gas sensors operable at room temperature. The films showed a reversible increase in resistance when exposed to ammonia and the response was found to be linear in the range of 0-100 ppm. The interaction of ammonia with tellurium film was investigated using Raman, X-ray photoelectron and impedance spectroscopy techniques. The results of Raman and XPS spectroscopy showed that ammonia reduces tellurium oxide present on the surface and grain boundary region of the film to tellurium. Results of impedance spectroscopy revealed that the change the resistance of the film after exposure of NH₃ is mainly contributed by intragrain region. On interaction with NH₃ the electrons trapped by adsorbed oxygen in the grain boundaries are released which decreases the majority carriers and thereby increases the resistance of the Te film.

6 illus, 1 table, 9 ref

006256   Sahoo N K;Thakur S;Senthilkumar M;Tokas R B; Das N C (Modular Lab, Spectroscopy Div, Bhabha Atomic Res Centre, Trombay, Mumbai-400 085) : Observation and analysis of self-organized surface grain structures in silica films under nonepitaxial growth mode. Vacuum 2004, 77(1), 87-96.

006255   Ramakrishnan V;Sai P S T (Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600 036) : Optimization of air distribution in direct reduction process in rotary kilns with pneumatic char injection. J Energy Heat Mass Transfer 2002, 24(3), 255-67.

An algorithm is proposed for optimization of air distribution in a direct reduction process in rotary kilns where pneumatic char injection and natural gas are used as a means of secondary heat supply, based on Pontryagin's continuous maximum principle. The optimum air distribution has been obtained for given operating conditions. The influence of kiln holdup on the performance of the direct reduction process in rotary kiln has been studied using a one dimensional dimensional steady state model and the process behavior has been analyzed. The results suggest a range of 17-20% to be the most suitable.

6 illus, 2 tables, 6 ref

006254   Pranav V;Anil kumar S;Balaji C (Heat Transfer and Thermal Power Laboratory, Department of Mechanical E, Indian Institute of Technology Madras, ) : Optimization of natural convection heat transfer from a horizontal cylinder with external longitudinal fins. J Energy Heat Mass Transfer 2002, 24(3), 269-79.

This is a sequel to the paper by Perumallu and Balaji in an earlier issue of this journal. In this study, the Nusselt number correlation developed in [1] is used determine the optimal heat transfer by natural convection from a horizontal cylinder with external longitudinal fins. The optimization of geometric and thermal parameters, important from design point of view, like, fin thickness fin heights, and fin thermal conductivities has been done. The optimization was done using a search algorithm and validated using the Newton Raphson technique.

5 illus, 3 tables, 5 ref

006253   Pathan H M;Lokhande C D (Phys Dep, Thin Film Phys Lab, Shivaji Univ, Kolhapur-416 004) : Chemical deposition and characterization of copper indium disulphide thin films. Appl Surf Sci 2004, 239(1), 11-18.

006252   Pancholi R M (Fionica Society, , Saru section road, Jamnagar 361 006 (Gujarat)) : A form of factorial function and its application. Phys Educ 2004, 20(3-4), 127-33.

The Stirling's approximate formula, viz., In (n!)~n In (n) or (n!) ~nⁿ e^-n, which is extensiely used in statistical mechanics, quantum statistics and mathematics, is valid only when the value of n is large. The new factorial function put forward in this paper not only has a form that is similar to the above mentioned approximate formula but it is also valid for values of n defined as: 3≤n≤∞.

3 ref

006251   Ong K S;Hamlaoui A (Monash University Malaysia,, , Bandar Sunway 46150 Petaling Jaya Malaysia) : Experimental observations of water-filled and R134a-filled thermosyphons operating at low temperatures. J Energy Heat Mass Transfer 2002, 24(3), 235-54.

Heat pipes are low cost and efficient heat exchangers. In the tropics they could be employed to perform heat exchange betwen the cold outgoing air and the warm incoming fresh air HVAC systems. Heat pipes are ideal for such low temperature energy recovery systems. Since R134a is an environmentally friendly refrigerant and water is cheap and readily available they are ideal liquids to use for filling the heat pipes. Both are suitable for low-temperature heat-pipe applications. In this paper, the heat transfer characteristics of a wickless heat pipe or thermosyphon filled with either water or R134a were obtained experimentally. The evaporator section was immersed in a hot water bath while the condenser section was wrapped in a concentric pipe water jacket. The effects of operating temperature difference between evaporator and condenser sections, fill ratio and the mass flow rate of he water in the cooling jacket of the condenser section on the peformance of the thermosyphon were determined. The results obtained indicated that the heat transfer rate and overall thermal coefficient of thermosyphons increased with increasing operating temperature difference, fill ratio and coolant water flow rate, and The water-filled thermosyphon was found to perform better than the R134a-filled unit.

21 illus, 2 tables, 22 ref

006250   Nazar R;Amin N;Pop I (Department of Mathematics, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia) : Mixed convction boundary layer flow from a sphere with a constant surface heat flux in a micropolar fluid. J Energy Heat Mass Transfer 2002, 24(3), 195-211.

The steady mixed convection boundary layer flow of an incompressible micropolar fluid about a sphere with a constant surface heat flux q_w is considered for both the assisting and opposing flow cases. The transformed conservation equations of the non-similar boundary layers are solved numerically using a very efficient finite-difference method known as the Keller-box scheme. Numerical results are presented for different values of the material and mixed convection parameters K and λ, respectively, and with the Prandtl number Pr=0.7. It is found that assisting flow (λ<62>0) delays separation of the boundary layer and can, if the assisting flow is strong enough, suppress it completely. The opposing flow (λ ≤<60>0), on the other hand, brings the separation point nearer to the lower stagnation point of the sphere and for sufficiently strong opposing flows there will not be a boundary layer on the sphere.

6 illus, 7 tables, 26 ref

006249   Lim K S;Babu P;Jayasankar C K;Lee S K;Pham V T;Seo H J (Phys Dep, Inst for Basic Sci Res, Chungbuk National Univ, Cheongju, 361-763, South Korea) : Optical spectroscopy of thulium-doped oxyfluoroborate glass. J Alloys Compounds 2004, 384(1-2), 12-18.

006248   Kandasamy R (Department of Mathematics, Institute of Road and Technology, Erode 638 316) : Effects of chemical reaction, heat and mass transfer on nonlinear boundary layer flow with thermal stratification and thermal diffusion in the presence of suction. J Energy Heat Mass Transfer 2002, 24(3), 223-33.

The problem is concerned nonlinear laminar boundary layer, chemical reaction, heat and mass transfer flow of an incompressible and viscous fluid past a continuously moving infinite vertical porous plate in the presence of suction under theinfluence of thermal stratification and thermal diffusion. The similarity transformation has been utilized to convert the governing nonlinear partial differential equations into nonlinear ordinary differential equations and then the numerical solution of the problem is drawn using R K Gill method. The analysis of this results obtained shows that the flow field is influenced appreciably by the presence of suction at the surface, chemical reaction and magnetic effects.

9 illus, 19 ref

006247   Ghatak A K;Goyal I C (Department of Physics, Indian Institute of Technology, New Delhi 110 016) : Use of confluent hypergeometric function in quantum mechanics and waveguide theory. Phys Educ 2004, 20(3-4), 115-116.

7 ref

006246   Ganesan P;Palani G (Department of Mathematics, Anna University, Chennai 600 025) : Free convection effects on impulsively stared semi-infinite inclined plate with constant heat flux. J Energy Heat Mass Transfer 2002, 24(3), 213-21.

An analysis is performed to study the transient free convection flow of a viscous incompressible fluid past an impulsively started semi-infinite inclined plate with constant heat flux. The dimensionless governing equations are unsteady, coupled and non-linear integro partial differential equations. Analytical methods fail to give a solution. Hence an implicit finite difference scheme of Crank-Nicolson method is employed. The velocity profiles are compared with exact solution for vertical plate and are found to be in excellent agreement. It is observed that the time required to reach steady state value is less with an increase in the inclination angle ϕ to the horizontal. The velocity is found to increase due to rise in an inclination angle ϕ with the horizontal. The velocity, temperature, skin friction and Nusselt number are shown graphically and are analyzed.

8 illus, 4 ref

006245   Derose D J;Krishnan J;Bhanumurthy K;Kale G B (Centre for design and manufacture, Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085) : Vacuum diffusion bonding of tunable disc-a component of linac accelerator. Bull Indian Vacuum Soc 2003, 6(4), 27-32.

The solid state bonding technique has been used to manufacture a tunable disc made of OFHC-Cu and austenitic stainless steel (AISI304). Joining of these materials have been carried out using Ni as an interlayer. In addition few specimens have also been bonded without Ni interlayer. Diffusion bonding experiments have been performed at temperature range from 750 to 900 °C for times up to 60 min and at a pressure from 10 to 20 MPa. Taking into account of the results of mechanical testing and microstrucal observation, for a sound bond, the optimum bonding conditions were obtained at temperature 850°C for 60 min at 10 MPa. Based on these studies a flow chart is made for the fabrication of the tunable disc.

4 illus, 1 table, 10 ref

006244   Datta S (NO, , 656, `Snehalata", 13th Main, 4th Stage, T K Layout, Mysore 570 009) : A Hypergeometric view of bessel functions in physics. Phys Educ 2004, 20(3-4), 85-114.

The family of Bessel functions as an offshoot of the solutions of the hypergeometric equation has been reviewed. Series and integral solutions of the hypergeometric equation are converted to the corresponding solutions of the confluent hypergeometric equation by the `confluence procedure". They are then converted to the family of Bessel functions through a connection formula, exploiting the condition c=2a. This condition leads to specialized solutions of the confluent hypergeometric equation, viz., logarithmic solution G(c<157>x) and an integral solution y1 (a<157>x) which make the transitions to Nv (z) and Jv(Z) transparent and easier. Finally the hypergeometric route to the asymptotic solutions of the Bessel equation has been reviewed.

17 ref

006243   Chattopadhyay A N;Dasgupta P;Jana Y M;Ghosh D (NO, B K C Coll, 111/2 B T Road, Bonhoogly, Kolkata-700 108) : Study on crystal field effect and single ion anisotropy in pyrochlore europium titanate (Eu₂Ti₂O₇). J Alloys Compounds 2004, 384(1-2), 6-11.

006242   Bhasin I J;Goyal N K;Jain V K (NO, Instruments Research & Development Establishment, Dehra Dun-248 001) : Electrooptical evaluation techniques of image intensifier tubes-part II. Def Sci J 2004, 54(4), 503-13.

Electrooptical evaluation techniques of image intensifier tubes for some of the important parameters like resolving power, absolute spectral responses of photocathode, spectral response of phosphor screen, modulation transfer function, recovery time, gas grade, and fixed-pattern noise have been described.

13 illus, 2 tables, 10 ref

006241   Awana V P S;Ansari M A;Gupta A;Saxena R B; Kishan H;Rawat R;Ganesan V;Narlikar A V;Buddhikot D;Malik S K (Superconductivity and Cryogenics Div, National Phys Lab, K S Krishnan Marg, New Delhi-110 012) : Induction of superconductivity in Y_0.4Pr_0.6Ba_2-xSr_xCu₃O₇ system with increasing sr substitution. Physica C 2004, 417(1-2), 33-39.

005242   Suman C K;Prasad K;Choudhary S N (University Department of Physics, T M Bhagalpur University, Bhagalpur 812 007) : Electrical properties of Pb₂Sb₃DyTi₅O₁₈ ceramic. Indian J Phys 2004, 78(8), 849-53.

Single phase orthorhombic tungsten bronze ceramics ofPb₂Sb₃DyTi₅O₁₈(PSDT) were prepared by a high temperature solid-state reaction method. Electrical impedance, phase angle, dielectric constant and dielectric loss have been measured in the frequency range 0.1 kHz o 3 MHz in the temperature region 28°C to 35°C. Dielectric studies show PSDT have low dielectric constant, low loss and undergo diffuse phase transition at 301°C. AC impedance analyses suggested the phase element to be capacitive. The activation energy has been estimated to be 0.62 eV from the temperature variation of dc resistivity. The nature of variation of resistivity with temperature suggested NTCR behaviour.

6 illus, 24 ref

005241   Suman C K;Prasad K;Choudhary R N P (University Department of Physics, T M Bhagalpur University, Bhagalpur 812 007,Bihar) : Diffuse phase transition in Pb₂Bi₃GdTi₅O₁₈. Indian J Phys 2004, 78(8), 855-9.

Single phase orthorhombic tungsten bronze ceramics ofPb₂Bi₃GdTi₅O₁₈ (PBGT) were prepared by a high temperature solid-state reaction method. Electrical impedance, phase angle, dielectric constant and dielectric loss have been measured in the frequency range 0.1 kHz to 3 MHz in the temperature region 25°C to 300°C. Dielectric studies show PBGT have low dielectric constant, low loss and undergo diffuse phase transition at 226°C. AC impedance analyses suggested the phase element to be capacitive. The activation energy has been estimated to 0.598eV from the temperature variation of dc conductivity. The nature of variation of conductivity with temperature suggested NTCR behaviour.

5 illus, 26 ref

005240   Sukhatankar K V;Narasale A M;Belekar M M; Arora B M (Phys Dep, Univ of Mumbai, Vidyanagari, Mumbai-400 098) : Low cost PC-based I-V measurement set-up for ion implanted semiconductor devices. Indian J pure appl Phys 2003, 41(1), 64-72.

10 illus, 1 table, 12 ref

005239   Srivastava K K P (Department of Physics, T M Bhagalpur University, Bhagalpur 812 007, Bihar) : Magnetic relaxation in nanoparticles of iron oxides: magnetic recording applications. Indian J Phys 2004, 78(8), 725-8.

The single domain anisotropic magnetic particles with high coercivity are suitable for magnetic recording and therefore magnetic relaxation effect which tends to destroy their magnetization is important. A quantum mechanical model was recently developed by the author to calculate the magnetic relaxation rate of nano-particles of iron oxides (magnetite and hemetite). These results have been applied to estimate their particle size for magnetic tapes/films on the consideration that the relaxation rate (magnetic fluctuation) must not be too high to wash out the magnetization produced by audio and visual electrical signals which operate at frequfencies 10²-10⁶ and 10⁹-10¹⁰ Hz respectively. In the first approximation it appears that particles of size 240-270 A (diameter) are suitable for audio recording and those of 190-200 A for video recordings. It is the first calculation of this type.

1 table, 11 ref

005238   Som T;Satpati B;Satyam P V;Kabiraj D;Gupta A; Mishra N C (Institute of Physics, , Sachivalaya Marg, Bhubaneswar 751 005, Orissa) : Swift heavy ion induced interface modification in metal/Ge systems. Indian J Phys 2004, 78(8), 815-18.

Reports on swift heavy ion induced interface modification in metal/Ge thin film bilayer system. 100 MeV Au⁷⁺ ions have been used for irradiationof the UHV grown thin films of Co/Ge and Ni/Ge at three different temperatures of 100 K, 300 K and 385 K and with fluences in the range of 5 x 10¹²ions/cm² to 1 x 10¹⁴ions/cm². Irradiation induced interfacial changes were studied by Rutherford backscattering spectrometry. The changes in the surface morphology andother structural aspects have been studied by transmision electron microscopy. Interface modification has been explained in terms of synergetic effect of electronic and nuclear energy loss processes.

4 illus, 18 ref

005237   Sinha S K;Barhal P K (Department of Applied Physics, Birla Institute of "Technology, Mesra-835 215, Jharkhand) : Study of defects in GaN/sapphire using rutherford backscattering spectroscopy and channeling. Indian J Phys 2004, 78(8), 739-42.

III-V nitrides like GaN, AIN, InV have opened up new opportunities in low-wavelength optical light emitters and in high frequency and high power electronic devices working at high temperature. But it is difficult to grow these materials due to lattice-mismatched substrate. GaN on sapphire were grown by MOCVD technique. Rutherford backscattering spectra together with channeling along {0001} axis were recorded to study the defects at the interface. Detail calculation shows that defects are distributed into the whole thickness of the film and are dislocations mainly aligned along the growth direction.

3 illus, 2tables, 8 ref

005236   Singh S S (Department of Physics, M S College (B B A Bihar University, Muzzaffarpur), Motihari 845 401, Bihar) : A simple theory for thermodynamics of liquids. Indian J Phys 2004, 78(8), 743-6.

A smiple theory for the thermodynamic properties of liquids is developed. based on the physical interpretation of the reciprocal of activity. Expressions for the effective pairpotentials are derived for different thermodynamic properties of the fluid. The theory os applied to estimate the effect of the triple dipole potential on the equationo f state and exces free energy of the liquid. The effect of the triple dipole potential, which increases with the increase of the atomic mass, is found to be small.

3 tables, 10 ref

005235   Singh A K (Math Dep, C L Jain (PG) Coll, Firozabad-283 203) : MHD free convection and mass transfer flow with hall current, viscous dissipation, joule heating and thermal diffusion. Indian J pure appl Phys 2003, 41(1), 24-35.

The combined effect of Hall current, viscous dissipation, Joule heating and thermal diffusion on the hydromagnetic free convection and mass transfer flow of an electrically conducting, viscous, incompressible fluid past an infinite vertical porous plate, has ben studied. The governing partial differential equations of this MHD-free convective boundary layer flow are reduced to non-linear ordinary differential equations by introducing suitable similarity transformations. the problem is solved analytically, and the velocity, temperature and concentration profiles are presented graphically. The skinfriction coefficient, the Nusselt number and the Sherwood number and calculated and presented. Finally, a thorough discussion has been presented for the results obtained.

10 illus, 4 tables, 20 ref

005234   Sharma J K;Parashar J;Mehta A S (Applied Phys Dep, Samrat Ashok Technol Inst, Vidisha (MP)-464 001) : Relativistic stimulated Raman scattering in a plasma channel. Indian J pure appl Phys 2003, 41(1), 73-6.

An intense laser radiation propagating in a plasma channel undergoes stinilated Raman scatering (SRS) and produces a Langmuir and a sideband electromagnetic wave. At higher laser power, relativistic effects become important. It has been found that, the growth rate is dependent on the localization of the Langmuir wave. The growth rate of the process is maximum near the axis.

^ssc1 illus, 17 ref

005233   Shah A K (Sheth R A Bhavan's Science College, , Khanpur, AHmedabad 380 001, Gujarat) : Lifetime of minority charge carriers in MoS_xSe_2-x layered compounds. Indian J Phys 2004, 78(8), 845-7.

The study on measurement of lifetime of the minority charge carriers in grown crystals of transition metal dichalcogenides (TMDC) material MoSxSe_2-x has been reported for stoichiometric variation X = 0,0.5, 1,1.5. The electrical field excitation method has been used for illuminating of the single crystal MoS_xSe_2-x. The lifetime of minority charge carriers have been evaluated from the analysis of exponential decay curve of the output voltage traced under swiping modeo f CRO. It is found from the present investigation that as X in the MoS_xSe_2-x TMDC layer compounds increase the lifetime of the charge carrier is also increases. The possible causes of such dependency of the lifetime of charge carriers on the stoichiometric variation in such TMDC layer compound are explained.

8 illus, 9 ref

005232   Sarkar S K (Electronics and Telecommunication Engng Dep, Jadavpur Univ, Kolkata-700 032) : Degradation of photon distribution and its effect on high frequency performance of 2D hot electrons in CdS quantum wells. Indian J pure appl Phys 2003, 41(1), 52-6.

The high frequency performance of two-dimensional hot electron in CdS quantum well is studied in the framework of the heated, drifted Fermi-Dirac distribution function, incorporating the relevant scattering mechanisms. The effects of non-equilibrium longitudinal optic (LO) phonons are also included in the calculations. the influences of large - q LO phonon and electron - LO phonon interaction at low qL_z are also studied. The ac mobility normalized by its de value is found to decrease with increasing frequency of the applied field beyond about 100 GHz while the drift velocity lags behind the applied field above, about 10 GHz. The degradation of phonon distribution enhances the 3 dB cut-off frequency at which the ac mobility drops to 0.707 ofits low frequency value.

3 illus, 18 ref

005231   Rout S K;Bera J (Department of Ceramic Engineering, National Institute of Technology, Rourkela 769 008, Orissa) : Dielectric properties of acceptor-doped SrTiO₃ ceramics. Indian J Phys 2004, 78(8), 819-22.

0.5 atom % Ni-doped SrTiO₃ was prepared by solid-state reaction route. Average grain sizes of un-doped and doped samples were 1.3 and 4.1 micron respectively. Relative permittivity of ST ceramics was found to increase with Ni-doping. Capacitance was measured at temperatures ranging from 400° to 700°C in the frequency range 10 Hz to 13 MHz. Grain and grain boundaries relaxation frequencies were shifted to higher frequency with temperature. Impedance measurements were conducted at 400°C to separate grain and grain-boundary contributions. Bulk and grain-boundary resistance were evaluated from impedance complex plain plot. Bulk resistance of doped and un-doped one, indicating GB resistance increases with acceptor doping.

5 illus, 12 ref

005230   Rout G C;Parhi N;Behera S N (Condensed Matter Physics Group, Govt Science College, Chatrapur 761 020) : Study of magneto-resistivity in manganite systems. Indian J Phys 2004, 78(8), 697-703.

Considers the band Jahn-Teller distortion in dynamic limit and ferromagnetism in the same itinerant e_g band of the manganese atom in presence of an external field. The electron Green's functions are calculated by Zubarev's technique for the colossal magnetoresistance system in presence of electron-phonon interaction. The Jahn-Teller distortion (e) and the magnetization (m) are calculated self consistently. The resistivity for the system is calculated from the electron relaxation time in Drude model taking into account the phonon frequencies in the Einstein limit. The temperature dependence of magneto-resistance is studied for different lattice coupling parameters and external magnetic field strengths. It is observed that the temperature variation of resistivity explains experimental results qualitatively.

6 illus, 15 ref

005229   Ray Chaudhuri B (Department of Physics, Presidency College, 86/1, College Street, Kolkata 700 073) : Study of spectral response of plant pigments for remote sensing applications. Indian J Phys 2004, 78(8), 677-80.

A common of different applications of remote sensing to plant sciences is to study the visible and infrared radiation reflected from vegetation canopies. The reflectance is governed by chlorophyll andother plant pigments and also by the presence of water, other tissues and the ground itself. Therefore the standardization of spectral response of the pigments is very important. The present work characterized the visible spectral response of chlorophyll and carotenoids at different growth stages of the leaves and justifies its capability to monitor maturity stages of vegetation. Only the visible region of spectral band is chosen because that is mainly concerned with the property of the vegetation itself. Instead of the amplitude of the peak reflectance band, as considered conventionally, the wavelength corresponding to the peak reflectance is taken into acount. To indicate crop maturity stage like `greenness" and `yellowness", fuzzy operations over reflectance data are suggested so as to simulate human reasoning.

4 illus, 2 tables, 6 ref

005228   Rai B (Department of Physics, R D S College, B R A Bihar University, Muzaffarpur 842 001, Bihar) : Thermodynamic properties of associating chain molecules. Indian J Phys 2004, 78(8), 689-92.

When a molecule has two or more anisotropic attraction sites, chain ring and tree-like cluster can form. The fraction of clusters of a given size can be estimated using purely statistical arguments. The effect of molecular associations on the attractive centers is investigated. Such a system's thermodynamic properties can be calculated by using expression based on a theory recently proposed by Wertheim. The approach is extended to examine associating chain molecules. In this study, the separate effects of molecular and chain size on the coexistence properties are investigated.

2 illus, 13 ref

005227   Prasad A;Kumar K N (University Department of Physics, Tilkamanjhi Bhagalpur University, Bhagalpur 812 007) : A proposal for the development of a fiber-optic interferometer for the determination of piezoelectric coefficient. Indian J Phys 2004, 78(8), 827-31.

Deals with the fabrication and characterization of different piezoelectric ceramics, polymers or their composites by finding their nonzero electromechanical coupling coefficients, the piezoelectric coefficients d_ij with the help of a self designed, sensitive, all-fiber Mach-Zehnder interferometer based on the principle of Pockels effect or acousto-optic effect with the aim of finding suitable materials in devices like variasters, electro-optic and acousto-optic modulators, transparent conductors, ultrasonic transducers, masers, phospher and gas igniters etc.

23 ref