004406   Singh K K;Sarma R;Das H L (Department of Physics, Gauhati University, Guwahati-781 014) : Poole-Frenkel photoconductivity in CdS thin films. Indian J Phys 2005, 79(6), 631-3.

Photoconductivity of thermally vacuum evaporated CdS thin films of thickness 294 nm grown on the glass substrates held at temperature 300 K, was studied at different applied fields and ambient temperatures. A gap-type film geometry with an effective gap of 7 mm between two pre-evaporated Ag electrodes was used. The conductivity was measured with an ECIL high input impedence (10¹⁴Ω) electrometer amplifier and was found to obey two distinct conduction mechanisms within the region of the applied fields. The photoconduction was found to be ohmic at low fields and of Poole-Frenkel type at high fields.

2 illus, 21 ref

004405   Shrivastava S K;Kailash;Raju K M (Department of Physics, Bundelkhand University, Jhansi-284 128) : Thermophysical properties of alkali halides. Indian J Phys 2005, 79(6), 647-9.

The thermophysical properties of alkali halides can be evaluated using their elastic constants which are obtained by ultrasonic techniques. The thermophysical properties are linearly dependent on the product of Debye temperature and square root of molecular weight. This dependency has been examined irrespective of bcc and fcc structure of alkali halides. Comparative study has been made between theoretical and experimental values of thermophysical properties of alkali halides.

2 tables, 5 ref

004404   Sharma P R;Sharma R P;Kuma R N;Mishra U;Gour Y N (Math Dep, Univ of Rajasthan, Jaipur-302 004) : Unsteady MHD flow and heat transfer along a horizontal porous plate in the presence of heat source and periodic free stream. Indian J Theor Phys 2005, 52(1), 11-18.

Unsteady flow and heat transfer of a viscous incompressible fluid along a horizontal, porous plate in presence of transverse magnetic field, heat source and periodic free stream is investigated. The velocity and temperature distributions are derived, discussed numerically and shown through graphs. The co-efficient of skin-friction and Nusselt number at the plate are derived, discussed numerically and their numerical values for various values of parameters are presented through tables.

3 illus, 2 tables, 9 ref

004403   Sengupta P R;Basak P (Math Dep, Univ of Kalyani, Kalyani-741 235) : Stability of viscous - visco-elastic (Maxwell) fluid in porous medium in presence of suspended particles. Indian J Theor Phys 2005, 52(1), 71-80.

An investigation is undertaken to study the Rayleigh-Taylor instability of visco-elastic Maxwell fluid underlying a Newtonian viscous fluid permeated with suspended particles in a porous medium. It is found that for potentially stable configuration, the system is always stable whereas for potentially unstable configuration, the system in unstable. The effects of horizontal magnetic field and uniform rotation also considered. For both stable to unstable configuration of hydromagnetic case, the system is stable if μ_eH²₀k²_k <62> 2π(p₁ + P₂)gk(a₂ - a₁) depending on magnetic permeability, magnetic field and densities of the fluid. The system is found to be unstable for potentially unstable cases in presence of uniform rotation.

18 ref

004402   Sen D (Centre for High Energy Physics, Indian Institute of Science, Bangalore-560 012) : Field theoretic studies of quantum spin systems in one dimension. Indian J Phys 2005, 79(6), 563-81.

Author has described some field theoretic methods for studying quantum spin systems in one dimension. These include the nonlinear σ model approach which is particularly useful for large values of the spin, the idea of Luttinger liquids and bosonization which are more useful for small values of spin such as spin-1/2, and the technique of low-energy effective Hamiltonians which can be useful if the system under consideration is perturbatively close to an exactly solvable model. Authors has applied these techniques to similar spin models, such as spin chains with dimerization and frustration, and spin ladders in the presence of a magnetic field. The comparative study illustrates the relative strengths of the different methods.

10 illus, 38 ref

004401   Sailaja S;Khan R A;Kumbhare S R;Naik P A; Gupta P D (NO, , 1/1 Ground Floor, Royal Garden, 12, Park Avenue, K P Puram, Chennai-600 028, Email: ssailaja@indiatimes.com) : Gaseous clusters as targets for use in laser plasma interaction experiments. Indian J Phys 2005, 79(6), 623-30.

Author has carried out various characterisation studies for different sonic and hypersonic nozzles, to optimise cluster formation in gas jets. Studies were done to decide optimum laser focus position for the nozzles and also to determine the best nozzle for laser-cluster interaction experiments. Argon gas cluster targets were irradiated by 1.5 J/25 ps laser pulses, from the fundamental beam of our Nd : phosphate glass laser. X-ray pinhole imaging of the laser produced cluster plasmas revealed information about the plasma column in the gas jet. High laser energy absorption of 80-85% was observed for argon clusters, and this was consistent with the intense X-ray emission signals measured using filtered X-ray PIN diodes.

7 illus, 19 ref

004400   Ritu;Jha I S;Singh B P;Choudhary V N;Singh R N (Department of Physics, T M Bhagalpur University, Bhagalpur-812 007) : Thermodynamic properties on CdNa alloys. Indian J Phys 2005, 79(6), 635-7.

The alloying behaviour of CdNa alloys is discussed on the basis of a simple theory based on the complex formation model. Though Cd and Na are simple metals but CdNa alloys exhibit anomalous behaviour. The excess free energy of mixing is negative in the region 0.6 ≤ C_Na <62> 0.1 and thereafter becomes positive. The concentration-concentration fluctuations in the long wavelength limit Scc(0) is larger than the ideal values Scc (0,id) up to C_cd= 0.55 and is less than ideal values for C_cd <62> 0.55. The concentration-dependent nature of asymmetry of the thermodynamic properties of mixing have been explained in the paper. The study reveals that Cd₂Na complex exists in the liquid phase close to melting temperature.

2 illus, 19 ref

004399   Raghavendra M K;Ramaswamy C R (Department of Physics, Bangalore University, Jnanabharathi Campus, Bangalore-560 056, Email: buiblab@yahoo.com) : Absolute intensity measurement of internal Bremsstrahlung from <. Indian J Phys 2005, 79(6), 619-22.

The Internal Bremsstrahlung (IB) spectrum from ⁵⁷Co has been re-measured in two separate experiments. In the measurement of IB in coincidence with 122 keV gamma rays of ⁵⁷Fe, the energy range of IB spectrum could be extended below 300 keV. In the other measurement involving IB in coincidence with K-X-rays of ⁵⁷Fe, the uncertainty in the end-point-energy value has reduced by almost a factor of two. In both cases, the measured intensity of IB spectra shows a good agreement with the theoretical predictions of Martin and Glauber.

8 illus, 16 ref

004398   Puri V;Darshane S;Shaikh S (Thick and Thin Film Device Lab, Department of Physics, Shivaji University, Kolhapur-416 004) : Moisture dependent Ku band microwave characteristics of red soil. Indian J Radio Space Phys 2004, 33(6), 399-404.

A study of the Ku band band (12-18 GHz) properties of red soil obtained from Shivaji University, Kolhapur, due to moisture has Been reported. The attenuation in the transmitted and reflected mode of the wetted soil has been measured using standard gain horn antenna. The effect of the angle of incidence (0° and 45°) is also reported. For very low moisture content, angle of incidence and angle of reflection dependent effects are observed. The results indicate that for very low moisture content detection in red soil, angle of incidence of 45° is more suitable and angle of reflection of 60° is most sensitive.

5 illus, 1 table, 14 ref

004397   Praveen V N;Mahadevan C K (Physics Research Centre, S T Hindu College, Nagercoil-629 002, Email: mahad@sancharnet.in ) : Electrical measurements on ZTS single crystals. Indian J Phys 2005, 79(6), 639-42.

ZTS single crystals were grown by the free evaporation method from aqueous solutions. Electrical measurements were carried out along a-, b- and c-directions of the grown crystals at various temperatures by the conventional parallel plate capacitor method. Study shows that the electrical parameters, viz. DC conductivity dielectric constant, dielectric loss factor and AC conductivity increase with the increase in temperature. Activation energies were also determined.

2 illus, 1 table, 21 ref

004396   Prabhakaran S R;Bhuvanendran C;Jyoti N;Devasi C V;Subbarao K S V (Department of Physics, University of Kerala, Karoavatton, Trivandrum-695 581) : Meridional wind derived from HF doppler radar and ionosonde over the magnetic equator. Indian J Radio Space Phys 2004, 33(6), 367-72.

The nature of plasma motion in the F-region at the magnetic equator is such that they are driven by the neutral air wind along the geomagnetic field. The meridional wind at the equatorial F-region is evaluated using HF Doppler radar of the Kerala University, Trivandrum (8.6° N, 77° E, dip 0.5°N) operated in spaced receiver configuration and ionosonde at equatorial station Trivandrum and an off-equatorial station Sriharikota (SHAR, 13.7° N, 80.2 °E, dip 10° N) for a few days during 1994-1995. The meridional component of the plasma drift at the magnetic equator is determined from the HF Doppler radar data by finding the time delay between the signals received at the central and north antennae by cross-correlation method. The thermospheric meridional wind is also determined by using h/F values obtained from the ionograms of both Trivandrum and Sriharikota. The temporal variation of meridional wind at the magnetic equator as determined by using both the HF Doppler and ionosonde methods show similar pattern. These results are compared with that obtained using HWM93. It was found that the magnitude of the poleward wind and its time of reversal depend on the altitude of the ionospheric layer.

2 illus, 24 ref

004395   Makarov I S (NO, , P.O.B. 1656, Tel Aviv 61015, Israel) : Spontaneous generation of neutrons in vacuum. Indian J Theor Phys 2005, 52(1), 51-62.

The method of the self-developing logical analysis and the adequate mathematical description has enabled to discover the phenomenon of spontaneous generation of mesons and neutrons in the vacuum, the first being the successive stages of the synthesis of the second. These particles are not elementary but consist of composiums, the components of the vacuum. The evolution and the mathematical description of these particles, found here, show that the high stability of the neutron is accounted for by its consistency with the vacuum. The results obtained shed light on the origin and the structure of the electron, some features of the measons, and the nature of the quarks.

5 ref

004394   Jaiswal S k;Ojha V N;Ajeet Singh (JVS & DC Standards, National Physical Laboratory, Dr K S Krishnan Road, New Delhi-110 012, Email: skjaiswal@mail.nplindia.ernet.in) : Estimation of uncertainty in measurement in precision calibration of DC high current source up to 100 A. J scient ind Res 2005, 64(9), 666-73.

Calibration of precision DC high current source (<62>2 A and up to 100 A), widely used in industries and research, has been discussed as case studies of transconductance amplifier and precision power supply calibration. Since transconductance amplifier requires boosting device for its operation, therefore effect of boosting device was added as an additional component of uncertainty. The various sources of uncertainty in measurement and their estimation based on Type A and Type B method as per ISO 'GUM' document are discussed in detail. The results are reported at coverage factor k=2 for approx 95% confidence level. The standards used for calibration are traceable to the 'National Standards' and their uncertainties were evaluated prior to use to avoid variation in results due to drift.

2 illus, 6 tables, 10 ref

004393   Gibson M S M;Lawrence N (Department of Physics, MEPCO Schlenk Engineering College, Sivakasi, Virudhunagar-626 005) : Diffusion of hydrogen and deuterium in Ni_0.5Fe_0.5 alloy - effect of pressure. Indian J Phys 2005, 79(6), 601-6.

The phonon dispersion in the substitutional fcc alloy Ni_0.5 Fe_0.5 has been calculated theoretically by applying Born-von Karman formalism including interaction upto fifth neighbours. The Mean Square Displacement (MSD) of surrounding host atoms with hydrogen and deuterium interstitials using Green's function technique and scattering matrix formalism are investigated for the temperature range (500 K-1250 K) from normal pressure to 2.5 GPa pressure. The MSD of atoms surrounding the interstitial are found to be smaller than those of host crystal. The diffusion parameters for hydrogen and deuterium are calculated using reaction coordinate technique for the temperature and pressure ranges mentioned above. It is found that the activation energy for hydrogen diffusion is less than that of deuterium diffusion and the diffusivity ratio D_H/D_2H approaches the value of 1.75 at higher temperatures. The results are compared with the existing results and a good agreement is observed.

4 illus, 17 ref

004392   Ghosh M;Mukherjee A;Karanjai S (Math Dep, Noth Bengal Univ, PO-North Bengal University) : Approximate H-function for anisotropic scattering 1.A: pomraning phase function. Indian J Theor Phys 2005, 52(1), 5-10.

Approximate forms of H-function Sen have been extended to the case of anisotropically scattering atmosphere with phase function given by Pomraning.

8 ref

004391   Gaftoi V;Ovando G;Lopez-Bonilla J (Area de Fisica AMA Division de CBI, Universidad Autonoma metropolitana-Azcapotzalco, Apdo. Postal 16-306, 02200 Mexico, D.F., Email: gaoz@correo.azc.uam.mx) : The fueter conditions as debye expressions. Indian J Theor Phys 2005, 52(1), 1-4.

For any analytic function f of the complex variable z, it is possible to prove that f(z) is a Debye potential for itself, which permits to re-formulate the corresponding Cauchy-riemann relations. Shows that the Fueter conditions when z is a quaternion-also accept a similar reformulation.

14 ref

004390   Datta T;Bhattacharya A B (Department of Physics, University of Kalyani, Kalyani-741 235) : Atmospheric electrical field in relation to severe meteorological disturbances. Indian J Radio Space Phys 2004, 33(6), 373-9.

Techniques and instrumentation for studying atmospheric electric field including the working principle of the field mill employed for the investigation are outlined. The variations of the electric field as observed over Kolkata during unusual meteorological disturbances are reported. During local precipitation, a significant reduction of electric field is noticed in the records, while in the occasions of local thunderstorms there is a pronounced increase of the electric field, sometimes, even showing a very intense value of more than 600 Vm^-1. The results have been discussed in the light of the source activity and further problems are focused.

7 illus, 18 ref

004389   Das K K (NO, , 34 Talbagan East Rd, Nonachandanpukur Barrackpore-700 122 West Bengal) : MHD flow of a dusty visco-elastic maxwell fluid through open rectangular channel. Indian J Theor Phys 2005, 52(1), 31-7.

Makes an attempt to investigate the hydromagnetic flow of a dustry visco-elastic incompressible (Maxwell) fluid through a long uniform tube of rectangular cross-section under the influence of an arbitrary pressure gradient. Laplace tranformation is used to solve the problem. Some particular cases for pressure gradient are also considered. In investigation of the titled problems, some related papers and books have been consulted.

15 ref

004388   Chauhan D S;Jain S (Math Dep, Univ Rajasthan, Jaipur-302 004) : Steady flow between highly permeable rotating disks. Indian J Theor Phys 2005, 52(1), 39-50.

The steady coupled flow between two rotating fluid-saturated highly permeable disks has been investigated. A modified set of boundary conditions, is applied at the fluid-porous medium interface taking effective viscosity of the fluid in porous medium, into consideration. The effects of the rotational Reynolds number, permeability of the porous medium and the effective viscosity parameter, on the velocity field have been studied.

4 illus, 19 ref

004387   Chakraborty A;Ojha S (Math Dep, Jadavpur Univ, Kolkata-700 032) : Flexure of a non-homogeneous cylindrically aeolotropic cylinder with a curtrate section. Indian J Theor Phys 2005, 52(1), 63-9.

Following the method of A. Chakraborty and Seegar and Pearson, the solution of the problem of flexure of a non-homogeneous anisotropic cylinder with a curtrate section has been solved.

8 ref

004386   Calla O P N;Kalita H S (NO, International Center for Radio Science, OM-NIWAS, A-23, Shastri Nagar, Jodhpur-342 003) : Estimation of scattering coefficient of saline soil for slightly rough surface and undulating surface at microwave frequencies. Indian J Radio Space Phys 2004, 33(6), 405-10.

Microwave remote sensing of soil requires the study of electrical parameters of the soil like (permittivity, emissivity and scattering coefficient) along with its physical parameters like surface roughness and undulation. Out of these the dielectric constant can be used for estimating emissivity and scattering coefficient. Microwave backscattering from soil depends on its dielectric constant. In the paper the scattering coefficient has been estimated for a slightly rough surface and undulating surface for saline soil, using the Perturbation Model and Geometric Optics Model. The database of the estimated scattering coefficient at X-band (8-10 GHz) for saline soil with different moisture content for both horizontal and vertical polarization and different look angles and two types of surfaces has been generated. The result shows that as the salinity increases, the scattering coefficient decreases. Also scattering coefficient increases with the increase in the moisture content. For active microwave remote sensing the scattering coefficient data for saline soil for different moisture content and for different types of surfaces are useful for image analysis and its applications. By using this database it is possible to design an active microwave sensor used for remote sensing of soil, which is largely useful in the field of agriculture.

4 illus, 7 ref

004385   Boruah B K;Baishya B (Department of Physics, Dibru College, Dibrugarh-786 003, Email: boruah_bipul@yahoo.co.in) : Comparison of microwave absorption and dielectric relaxation of some benzene derivatives and their binary mixtures. Indian J Phys 2005, 79(6), 643-5.

The dielectric absorption of some benzene derivatives and their binary mixtures have been studied at 10.03 GHz frequency in the range of temperature of 25°C-45°C. The relaxation time, dipole moment, and the thermodynamic parameters, free energy of activation (ΔF_ε), enthalpy of activation (ΔH_ε) and entropy of activation (ΔS_ε) for relaxation process have been measured. The results have been discussed on the basis of molecular size, molecular polarity, molecular environment, molecular interaction, effect of localisation of charge density and contribution for the formation of H-bond structure.

2 tables, 9 ref

004384   Ahmed M A;Abo Ellil M S;El-Dine M T (Department of Physics, Faculty of Science, Cairo University, Giza, Egypt, Email: moala47@hotmail.com) : Enhancement of the transport and dielectric behaviour of pure and blended CPVC by metal ions. Indian J Phys 2005, 79(6), 651-5.

The AC conductivity and the dielectric properties were measured as a function of temperature and frequency for the pure and blended chlorinated poly vinyl chloride (CPVC) polymer samples. The DC conductivity was measured in the same range of temperature. The effect of metal ion concentration as well as its ionic radius on the above properties was studied. The measurements of conductivity showed the existence of more than one conduction mechanism. Both DC and AC conductivities increase with increasing the metal ion content. The obtained values of the activation energy indicate the semi conducting behaviour for metal-doped samples.

5 illus, 1 table, 21 ref

004383   Acharya D P;Mondal A (NO, Bangabasi Morning Coll, Kolkata-700 009) : Effect of rotation on rayleigh surface waves under the linear theory of non-local elasticity. Indian J Theor Phys 2005, 52(1), 81-9.

Deals with the propagation of Rayleigh surface waves in an elastic semi-infinite rotating solid medium under the linear theory of non-local elasticity. It is shown that these waves are dispersive in nature where as classical Rayleigh waves and Rayleigh waves in a rotating body are non-dispersive.

12 ref

003423   Yajiang L;Juan W;Yansheng Y;Haijun M (Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, China, Email: yajli@sdu.edu.cn) : Diffusivity of Al and Fe near the diffusion bonding interface of Fe₃Al with low carbon steel. Bull Mater Sci 2005, 28(1), 69-74.

The distribution of elements near the Fe₃Al/Q235 diffusion bonding interface was computed by the diffusion equation as well as measured by means of EPMA. The results indicated close agreement between the two for iron and aluminium. Diffusion coefficient in the interface transition zone is larger than that in the Fe₃Al and Q235 steel at the same temperature, which is favourable to elemental diffusion, The diffusion distance near the Fe₃Al/Q235 interface increased with increasing heating temperature, T, and the holding time, t. The relation between the width of the interface transition zone, x, and the holding time, t, conformed to parabolic growth law: x²- 4.8 x 10⁴ exp(- 133/RT), (t -t₀). The width of the interface transition zone does not increase significantly for holding times beyond 60 min.

7 illus, 3 tables

003422   Yadav R P;Sharma R (Department of Physics, Govt. P.G. College, Bisalpur (Pilibhit)-262 201) : Effect of gravity on weak converging shock waves in water. Acta Cienc Indica-Phys 2005, 31(1), 95-116.

Neglecting the effect of overtaking disturbances, Chester-Chisnell-Whitham method has been used to study effect of gravity on weak converging shock waves in water. Analytical relations for flow variables have been obtained for initial density distribution <114>₀ = <114>r/^<109>, where <109> is a constant and <114>' is the density at centre/axis of symmetry. Finally the results obtained are compared with those obtained earlier.

25 illus, 21 tables, 10 ref

003421   Upadhyay P N;Yadav N (Department of Physics, Nalanda Mahila College, Biharsharif-803 101) : Status of the <104> (548) Meson. Acta Cienc Indica-Phys 2005, 31(1), 43-60.

The <104> is well established meson at its mass (547.30 <145>0.1) MeV and full width (1.18 <145> 0.11) KeV: Its quantum number are CI^G J^P = + 0⁺ 0^-. Its main decay modes are 2<103>, 3<112>⁰<112>⁺<112>^- <112> and e⁺e^-<103>. An account of its theoretical and experimental results has been presented.

6 illus, 2 tables, 79 ref

003420   Ubale A U;Kulkarni D K (Department of Physics, Govt Vidarbha Institute of Science and Humanities, Amravati-444 604, Email: ashokuu@yahoo.com) : Preparation and study of thickness dependent electrical characteristics of zinc sulfide thin films. Bull Mater Sci 2005, 28(1), 43-7.

Zinc sulfide thin films have been deposited onto glass substrates by chemical bath deposition. The various deposition parameters such as volume of sulfide ion source, pH of bath, deposition time, temperature etc are optimized. Thin films of ZnS with different thicknesses of 76-332 nm were prepared by changing the deposition time from 6-20 h at 30<144>C temperature. The effect of film thickness on structural and electrical properties was studied. The electrical resistivity was decreased from 1.83 x 10⁵ <87>-cm to 0.363 x 10⁵ <87>-cm as film thickness decreased from 332 nm to 76 nm. The structural and activation energy studies support this decrease in the resistivity due to improvement in crystallinity of the films which would increase the charge carrier mobility and decrease in defect levels with increase in the thickness.

5 illus, 7 tables, 15 ref

003419   Singh V;Tiwari M;Gundu Rao T K;Dhoble S J (Department of Physics, Regional Institute of Education, Bhopal-462013, Email: vijayjiin@hotmail.com) : Luminescent studies of impurity doped SrS phosphors. Bull Mater Sci 2005, 28(1), 31-4.

SrS phosphors activated with Ce and Dy ions were prepared by solid-state diffusion method. Photoluminescent study was carried out on SrS : Ce, SrS : Dy and SrS : Dy, Ce. Thermoluminescence and electron spin resonance studies were also carried out on SrS : Dy phosphor. The thermoluminescence glow curve shows a peak at around 142<144>C. Irradiated SrS : Dy exhibits an ESR line due to a defect centre. Thermal annealing behaviour indicates that this centre correlates with the TL peak at 142<144>C. The centre is characterized by an isotropic g -value of 2.0039 and is assigned to a F⁺ centre.

5 illus, 20 ref

003418   Singh R S;Singh R S;Anzer A;Singh N P;Sinha A K;Verma P K;Mishra L K (Department of Physics, Magadh University, Bodh Gaya-824 234) : An evaluation of thermal conductivity of <. Acta Cienc Indica-Phys 2005, 31(1), 37-42.

Thermal conductivity of³ He-⁴. He liquid mixtures near the <108> line using the theoretical formalism of Dohm and Folk [Phys. Rev. B 28, 1332 (1983)]. Experiment on thermal conductivity show a rapid departure for dilute mixtures from the behaviour of pure 4He as concentration X increases. Authors have evaluated the thermal conductivity Kasa function of (T- T<108>)/ T<108> for X = 5 x 10^-2, 3 x 10^-2,1 x 10^-2, 1 x 10^-3 and 1 x 10^-4. Our theoretical results indicates that as X decreases K increases with (T- T<108>/T<108>.

3 tables, 25 ref

003417   Singh R K;Singh S N (Department of Physics, C.M Science College, Darbhanga, Bihar) : Realization of SC active networks. Acta Cienc Indica-Phys 2005, 31(1), 139-43.

SC equivalent resistance has been produced and such resistance has been employed with op-amp, the performance of op-amp, is found to be improved. Well known active circuits are compared with SC networks, their performance is studied. In the differential integrator the resister is replaced by SC circuit. The magnitude response of this circuit has been studied and results are compared with its active network counter part.

5 illus, 1 table, 8 ref

003416   Shalini K;Shivashankar S A (Materials Research Centre, Indian Institute of Science, Bangalore-560 012) : Oriented growth of thin films of samarium oxide by MOCVD. Bull Mater Sci 2005, 28(1), 49-54.

Thin films of Sm₂O₃ have been grown on Si(100) and fused quartz by low-pressure chemical vapour deposition using an adducted <98>-diketonate precursor. The films on quartz are cubic, with no preferred orientation at lower growth temperatures (<126> 550<144>C), while they grow with a strong (111) orientation as the temperature is raised (to 625<144>C). On Si(100), highly oriented films of cubic Sm₂O₃ at 625<144>C, and a mixture of monoclinic and cubic polymorphs of Sm₂O₃ at higher temperatures, are formed. Films grown on either substrate are very smooth and fine-grained. Infrared spectroscopic study reveals that films grown above 600<144>C are free of carbon.

6 illus, 22 ref

003415   Saxena S K (Department of Physics, Upadhi (P.G.) Mahavidyalaya, Pilibhat-262 001) : Analysis of wave operators for trace for class perturbations. Acta Cienc Indica-Phys 2005, 31(1), 117-20.

Strong wave operator have been derived under the assumption that HJ-JH₀ is a trace operator.

8 ref

003414   Saxena N;Saxena M (Department of Physics, Moradabad Institute of Technology, Ramganga Vihar, Phase-2, Moradabad-244 001) : An overview of current status of renewable energy resources in India. Acta Cienc Indica-Phys 2005, 31(1), 135-7.

As the second largest country of the world undergoing explosive growth, India represents a unique and little-tapped source of expertise on multifarious issues of economics and social development. Among many problems of concern, the development of alternative sources of energy is crucial to the future well being of India indeed, of the globe. Yet in spite of its great practical need and considerable human and institutional resources, India remains a blind spot in the view of many professional from the fields of energy and international development.

2 tables, 4 ref

003413   Saha S L;Rezaul Hauque Khan M;Sawaki N (Department of Applied Physics and Electornics, University of Chittagong, Chittagong-4331, Bangladesh, Email: rhkcu@yahoo.com) : Deep level studies of GaN by deep level transient spectroscopy. Indian J Phys 2005, 79(5), 491-5.

Deep level studies of undoped lightly-doped and moderately-doped GaN have been done, the dopant being Mg. An energy level of L, = 0.25 eV has been observed in all three types of samples and is considered to be due to unintentional dopant/impurity present in the grown sample. The concentration of this L₁ level is independent of doping, level. Another level L₃, = 0.62 eV has been observed in lightly-doped and moderately-doped samples. The concentration of this L₃ level depends on the doping concentration and is considered to be due to Mg dopant. Another broad energy level L₂, has been observed only in lightly-doped sample but does not appear in undoped and moderately-doped sample. The broadening and peak height of this L₂ level are attributed to the contribution of more than one deep level. The origin and disappearance of this L₂, level in undoped and moderately-doped sample is not clear.

6 illus, 1 table, 30 ref

003412   Sable M C;Labde B K;Shamkuwar N R (Department of Physics, Dr Babasaheb Ambedkar Marathwada University, Aurangabad-431 004, Email: mcsable@rediffmail.com) : X-ray and magnetic studies of Zn<. Bull Mater Sci 2005, 28(1), 35-7.

Seven samples of the polycrystalline, Ni_1.25-xZn_xPb_{0.25Fe1.5O4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) ferrites, were prepared by usual double sintering ceramic method. X-ray diffraction patterns of the samples revealed single-phase cubic spinel structure. The magnetic properties were investigated by means of magnetization and a.c. susceptibility (X) measurements. A.C. susceptibility was measured from room temperature to the Curie temperature (Tc) of the samples. Variation of a.c. susceptibility (X) with temperature showed that the samples with x = 0.3 and 0.5 contain single-domain (SD) particles whereas the samples with x = 0.4 and 0.6 showed multi-domain (MD) nature. Values of Curie temperature (Tc ) as obtained from the study of variation of a.c. susceptibility with temperature were found to decrease with increase in the Zn²⁺ concentration (x). Magnetic measurements showed increase in magnetization as Zn²⁺ content was increased from 0.0 to 0.5. Further increase in Zn2+ content (x) reduces the magnetization.}

2 illus, 1 table, 19 ref

003411   Ranga Nayakulu S V;Venkateswar S;Sreenivasa Reddy C;Reddy D L (Department of Physics, University College of Sciences, Osmania University, Hyderabad-500 007) : Kinetic studies on changes of ultrasonic velocities in the mixing of solvents. Acta Cienc Indica-Phys 2005, 31(1), 125-9.

Kinetic studies have been carried out by measuring ultrasonic velocities (<110>) in the mixing of bases like aniline, acids like phenol with esters like ethyl acetate and with octonol as hydroxylic solvent. The ultrasonic velocities (<110>) were measured using ultrasonic pulse echo system (model UX4400-M) on mixing of different solvents at various concentrations and at different temperatures. The results are interesting because increase in the basic content in the binary mixture increases the ultrasonic velocity (<110>), where as increase in acid content decreases the ultrasonic velocities. Kinetically, the mixing process is first order in the reactive component, acid or base. Another important feature is effect of solvents like octonol instead of ethyl acetate on the kinetic process. The reaction rate is larger with octonol compared to ethyl acetate. Arrhenius parameters were computed for phenol-ethyl acetate system and energy of activation (E_a), enthalpy of activation (<68>H). Free energy of activation (<68>F) and entropy of activation (<68>S) are the right order of magnitude for these kinetic processes.

6 tables, 12 ref

003410   Ramesh K;Arumugam V;Mohan Kumar G (Department of Physics, Annamalai University, Annamalai Nagar-608 002) : Electrical resistivity measurements in concrete structures by four probe resistivity method. Acta Cienc Indica-Phys 2005, 31(1), 71-80.

The scope of electrical resistivity measurements as a non-destructive technique for concrete structures has been examined. It is shown that there is a linear relationship between resistivity, porosity and compressive strength. An important observation is that a highly porus concrete, specimens are having very high resistivity values which mean low strength. The study also shows that a battery operated portable resistivity meter can be conveniently used as a non-destructive testing tool for in situ measurements on concrete structures.

9 illus, 4 tables, 27 ref

003409   Ramesh K;Arumugam V (Department of Physics, Annamalai University, Annamalai Nagar-608 002) : Specific gravity and porosity studies in some selected wood specimens. Acta Cienc Indica-Phys 2005, 31(1), 131-3.

The porosity and specific gravity measurement have been carried out in some selected wood specimens using water absorption and mercury method. Some cases have been tested and the results are also given in the text.

1 table, 6 ref

003408   Raj D;Meetu (Department of Physics, C.C.S. University, Meerut-250 004) : Differential cross sections for e- CO elastic scattering. Indian J Phys 2005, 79(5), 529-31.

In a recent investigation, Raj and Kumar [Phys. Lett. A282 284 (2001)] modified the absorption potential of Staszewska et al [Phys. Rev. A28 2740 (1983)] in such a way that it yielded the best agreement between theory and experiment for elastic cross sections when applied to e<96> - O₂ scattering over a wide incident energy range same modified absorption potential of Raj and Kumar has been employed to obtain the elastic differential cross sections (EDCS) for electron scattering by CO molecules at intermediate energies (100-800 eV). The independent atom model alongwith partial waves has been used for these calculations. The results of EDCS are in fairly good agreement with the experimental data.

3 illus, 11 ref

003407   Nair S U K;Warriar P R S;Koshy J (Department of Physic, University College, Trivandrum-695 034, Email: sukn@rediff.com ) : Ba₂ErNbO₆: a new perovskite ceramic substrate for Bi(2223) superconducting thick films (T_c(0) = 110 K). Bull Mater Sci 2005, 28(1), 39-41.

Barium erbium niobate (Ba₂ErNbO₆) has been developed as a new substrate for (Bi,Pb)₂Sr₂Ca₂Cu₃O_x [Bi(2223)] superconductor film. Ba₂ErNbO₆ (BENO) has a cubic perovskite structure with lattice constant, a = 8.318 Angstrum. The Bi(2223) superconductor does not show any detectable chemical reaction with BENO even under extreme processing conditions. Dip coated Bi (2223) thick film, Ba₂ErNbO₆ substrate, gave a T_c (0) of 110 K and current density of <126> 4 x 10³ A cm^-2 at 77 K and zero magnetic field.

5 illus, 1 table, 10 ref

003406   Kokate S;Mahajan S K;Machwe V G;Mehta A S (Department of Applied Physics, Samrat Ashok Technological Institute, Vidisha-464 001, Email: sachin_k_mahajan@rediffmail.com) : Luminescence and upconversion process in Er<. Indian J Phys 2005, 79(5), 533-5.

The photoluminescence properties of Er³⁺ doped alkali telluride glasses are investigated. The matrix system is 80Te₂O₂ -20Na₂ CO₃-Er₂O₃. We grows glasses at varying concentrations of Er from 0.5<37> to 2.5<37> The Stokes luminescence characteristics under 380nm excitation have been studied and intense green emission was observed from samples of Er³⁺ doped glassy material. Infrared to visible upconversion has been observed under IR at 800 nm excitation. Visible upconversion center at 540nm corresponding to the ⁴S_3/2<142>⁴I_15/2 in Er, sharp intense green emission occurs when concentration of Er₂O₃ is about 1.5 mol<37>. Excited state absorption is discussed as possible mechanisms for the upconversion process under IR excitation.

3 illus, 9 ref

003405   Kalita P K;Sarma B K;Das H L (Department of Physics, Guwahati College, Guwahati-780 021, Email: pkkgc@yahoo.co.in) : Space charge limited positive and negative photoconductivity in CdTe thin films. Indian J Phys 2005, 79(5), 497-502.

Thermally evaporated CdTe thin films, having thickness in the range of 1000-4700Angsturm and deposited within the substrate temperature 473K -583K, show weak crystailinity and cause both space charge limited positive and negative photconductivity. The occurrence of negative photoconductivity depends on the applied field, temperature and the illumination level, which is governed by the minority carrier hole's optically freed from the trapping centers. The prime deep trap depths responsible for negative photoconductivity are 0.514<145>0.002 ev ands 0.516 <145> 0.002 eV estimated from thermally stimulated current, as well as, SCLC measurements. The positions of electron Fermi level and recombination centers are calculated as 0.57eV and 0.77eV-for n-type CdTe thin films.

8 illus, 1 table, 25 ref

003404   Gunsekaran S;Sankari G (P.G. & Research Department of Physics, Pachiyappa's College, Chennai-30) : Analysis of cyanocobalamin by spectroscopic measurements. Acta Cienc Indica-Phys 2005, 31(1), 61-70.

The infrared, Raman and UV-visible spectroscopic measurements are employed for the qualitative analysis of a pharmaceutical active compound, cyanocobalamin. Cyanocobalamin is commonly known as vitamin B₁₂ and is used in the treatment of megaloblastic anemia. The different functional groups present in the compound are identified and assigned satisfactorily using the FTIR and FT Raman spectra. The UV-visible spectral measurement carried out on the compound identifies three wavelength maxima. By exposing the drug to various environmental exposures like infrared radiation and sun light, the qualitative change in the behaviour of the drug is tested by employing internal standard calculations among the wavelength maxima. The interaction of the compound with some trace elemental concentrations such as sodium and calcium has been analysed by employing UV-visible spectral measurements.

4 illus, 4 tables, 11 ref

003403   Gunasekaran S;Natarajan R K;Rathikha R; Syamala D (Post Graduate and Research Department of Physics, Pachaiyappa's College, Chennai-600 030) : Fourier transform infrared and fourier transform raman spectra and normal co-ordinate analysis of benzocaine. Indian J Phys 2005, 79(5), 509-13.

Benzocaine is one of the important local anaesthetic with molecular formula C₉ H₁₁ NO₂. This has been used as a cutting agent in the illicit drugs. Fourier transform infrared (FTIR) and Fourier transform Raman (FTR) spectra of benzocaine contain a number of bands at specific wave numbers. A detailed vibrational analysis has been made in deciding which of the vibrational modes gives rise to each of these observed modes. A normal coordinate analysis has been carried out for benzocaine assuming the ethyl group as point mass. A set of molecular constants has been evaluated on the basis of C_s symmetry. The evaluated potential constants have been compared with those of related molecules and are in good agreement with the literature. To check whether the chosen set of normal coordinates contribute maximum to the potential energy associated with the normal coordinates of the molecule, potential energy distribution (FED) has been evaluated.

2 illus, 1 table, 12 ref

003402   Gopalakrishna G S;Doreswamy B H;Mahesh M J; Mahendra M;Sridhar M A;Shashidhara Prasad J;Ashamanjari K G (Department of Studies in Physics, University of Mysore, Mysore-570 006) : Hydrothermal synthesis, structure and characterization of new NASICON related potassium iron (III) pyrophosphate. Bull Mater Sci 2005, 28(1), 1-7.

A new potassium iron (III) pyrophosphate was synthesized by hydrothermal technique and characterized by X-ray studies. The compound crystallizes in a monoclinic space group, P2₁/c, with cell parameters, a = 7.365(2) Angstrum, b = 10.017(2) Angstrum, c = 8.214(1) Angstrum, <98> = 106.50(1)<144> and Z = 4. The structure has tunnel-type cavities and are congenial for ion transportation through them. The compound exhibits moderate thermal stability.

7 illlus, 5 tables, 19 ref

003401   Ghanshyam;Tripathi V K (Department of Physics, Bihar Institute of Technology, Sindri, Dhanbad-828 123) : Stimulated Raman scattering instability of laser beam propagating through a collisional plasma in a self-focused filament. Indian J Phys 2005, 79(5), 515-21.

The stimulated Raman scattering instability is treated for laser beam propagating through a collisional plasma in a self-focused filament where nonlinear refraction due to the redistribution of the electron density caused by nonuniform ohmic heating of electron is balanced by diffraction divergence. The filament supports radially localized Langmuir waves. A high power laser beam propagating through a collisional plasma breaks into high-intensity filaments of size <126>c/<119>_p where c is the velocity of light in vacuum and <119>_p is the plasma frequency. Inside a filament, the laser undergoes stimulated Raman backscattering (B-SRS). Since the temperature inside a filament is higher and density is lower than those outside, the collisional damping rates of the decay waves are lowered and hence, the threshold power for B-SRS is reduced. It is shown that self-focusing of perturbations in the incident laser beam can greatly enhance the growth rate of the instability. This result may help to explain experimental observation of Raman scattering at nominal incident intensities well below the theoretical threshold.

2 illus, 11 ref

003400   Dileep Kumar;Jha H K (Department of Mathematics, K B Jha College, Katihar, Bihar) : Solutions of static charged spheres in general relativity. Acta Cienc Indica-Math 2005, 31(1), 159-64.

A new formalism to obtain Einstein-Maxwell's equation / for static charged spheres has been reported. The present formalism is more suitable to derive new solutions of Einstein-Maxwell's equations for static spheres. The present solution is very strong gravitational field with <101> = 2<114> and accordingly they also exhibit singularities at the centre. It may further be added that it is possible to give a direct generalization of the present formalism to the case of a charged anisotropic fluid of null conductivity. Also, the present formalism helps us to analyse the role of the energy density of the free gravitational field in relation to matter and charge densities.

10 ref

003399   De S;Datta T;De M;Bhattacharya A B (Department of Physics, University of Kalyani, Nadia-741 235) : Variability of Indian monsoon and its rainfall forecasting. Indian J Phys 2005, 79(5), 475-71.

The present state of knowledge out the variability of Indians monsoon with special emphasis on the intra-seasonal and inter-annual variation of the monsoon giving importance to 'monsoon jets', seasonal oscillations, annual viriability and coherent intra-seasonal oscillations are discussed at length. Different techniques and models implemented for forecasting monsoon rainfall have been throughly considered. A link between stratosphere and monsoon rainfall is examined. The instability characteristics of monsoon disturbances are outlined. Finally, scope of future investigations are pointed out.

6 illus, 1 table, 131 ref

003398   Dabhi R M;Parekh B B;Joshi M J (Crystal Growth Laboratory, Department of Physics, Saurashtra University, Rajkot-360 005, Email: mshilp24@hotmail.com) : Dielectric studies of gel grown zinc tartrate crystals. Indian J Phys 2005, 79(5), 503-7.

Zinc dextro tartrate and zinc levo tartrate crystals were grown by using, opticilly sensitive dextro tartaric acid and levo tartaric acid, respectively. These crystals were grown by a single diffusion gel growth technique using silica hydro gel. The variation in dielectric constant and loss tangent values, for both zinc dextro tartrate and zinc levo tartrate crystalline samples, was measured at different temperatures in the frequency range from 5 kHz to 1 MHz. A sharp peak was observed in the dielectric constant versus temperature plots at 121.52<144>C indicating a phase transition. Beyond this temperature, the Curie- Weiss law was found to be followed; the variation of the dielectric constant with frequency was also studied. The results are discussed.

9 illus, 16 ref