021338   Lakshmanan R (School of Physics, Sains Malaysia Univ, Pualu Penang-11800, Malaysia, Email: lp_dde_au@yahoo.com) : Validity of theoretical models in estimating the sound velocity in toluene-alcohol mixtures. Indian J Phys 2008, 82(11), 1503-12.

Four different theoretical models have been applied to evaluate the sound velocity values at 303 K for the systems studied in our previous work and they are compared with the experimental values. The validity of the Nomoto's relation, the ideal mixing relation, the free length theory and the Rao's specific velocity method is checked and a comparative study of the above models is made. The least square linear fitting equations are generated for additional confirmation. The non-ideal behaviour of the systems is explained in terms of molecular interactions of the constituents of the mixture.

8 illus, 2 tables, 15 ref

021337   Karot K M;Antony B;Vinodkumar M (V P & R P T P Science College, , vallabh Vidyanagar-388 120) : (NULL). Prajna 2008, 16(Oct), 110-20.

Reported calculations of total ionization cross sections (Q_ion for the boron chlorides, BCI_x (x=1-3) upon electron impact at energies from circa threshold to 2000 eY. Sphelical Complex Optical Potential (SCOP) formalism is employed to evaluate total inelastic cross section, Q_inel. The Q_ion are derived from the Q_inel using our Complex Spherical Potential - ionization contribution (CSP-ic) method. Mutual comparison of ionization cross sections for all boron chlorides is carried out to get a general picture of contribution of individual ionization cross sections. Present calculations also provide information, hitherto sparse, on the excitation processes of these targets. The results are compared with available experimental and other theoretical data and overall good agreement is Observed.

4 illus,2 table, 24 ref

021336   Karmakar M;Sarkar B K;Barman S;Mazumdar P S; Dorendrajit Singh S;Bhattacharya M (Physics Dep, A.P.C. College, New Barrackpore, Kolkata-700 131, Email: mahua_apc@yahoo.com) : Evaluation of kinetic parameters from thermoluminescence glow curves. Indian J Phys 2008, 82(11), 1495-1502.

Two methods of determination of trapping parameters from thermoluminescence glow curves are considered. One is due to Kirsh and the other is suggested by Vejnovic et al. By taking into account both the computer generated and the experimental TL peaks, it is established that the Kirsh method is superior to that of Vejnovic et at. The possible application of Kirsh method to the case of temperature dependent frequency factor is also studied.

2 tables, 19 ref

021335   Eriksen E;Gron O (Institute of Physics, University of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo, Norway, Email: Oyvind.Gron@iu.hio.no) : Significance of the Schott energy in the electrodynamics of charged particles and their fields. Indian J Phys 2008, 82(9), 1113-7.

The significance of the Schott four-momentum in the energy-momentum conservation account of a charged particle and its electromagnetic field is analyzed. Periods with preacceleration and run away motion are discussed. The existence of pre-radiation is demonstrated. The Schott energy is identified as field energy localized just outside the particle. Giving first a description with reference to an inertial frame, the analysis is then extended to a more general description valid also with reference to a uniformly accelerated frame. It is shown that the Schott energy accounts for the energy radiated by a freely falling particle. The non-invariance of electromagnetic radiation from a charged particle under transformations involving accelerated motion is discussed.

6 illus, 27 ref

021334   Dubey J D;Kushwaha J P;Prasad B (Physics Dep, Vinobha Bhave Univ, Hazaribag-825 301, Email: jd_dube2004@yahoo.co.in) : Surface stress calculation for one-monolayer adsorption of as on the Si(001) and the Ge(001) surface. Indian J Phys 2008, 82(12), 1701-5.

Reports a surface stress calculation for one-monolayer adsorption of As on the Si(001) and the Ge(001) surfaces. The density functional theory within local density approximation has been used. A comparison of our two results show that the As-adsorbed-Ge surface is more isotropic than the As-adsorbed-Si surface. The adsorption of As removes the original Si (Ge) asymmetric dimers and forms symmetric dimers. This is attributed to the decrease in stress anisotropy due to the introduction of defects on the surface. This inference is in agreement with that of He and Zhang who studied a Sb-adsorbed-Si(001) surface.

^ssc1 table, 18 ref

021333   Deo B B;Mishra P K (Physics Dep, Utkal Univ, Bhubaneswar-751 004, Email: bdeo@iopb.res.in) : Calculation of the masses and the running masses of the quarks and leptons from electroweak to supersymmetric grand unification. Indian J Phys 2008, 82(11), 1529-61.

Makes a systematic theoretical analysis of the masses of the fermions and their variation with energy by solving the one loop renormalization group equation (RGE) in the Minimal Supersymmetric Standard Model (MSSM). A simple common mass for all the fermions around 115 GeV at GUT scale has been found as a possible solution of RGE by Deo, Maharana and Mishra. Here we undertake the unfinished but the important task of calculating the electroweak masses of the fermions at different energies. The proposed parametric unification mass and group theoretic constants for the model are well known. The mass of the top quark and its descent is studied by an approximate method very carefully. Finds that the Ramond, Roberts and Ross value of the Wolfenstein parameter is reproduced and is nearly equal to 0.22. When raised to integral powers and multiplied by 115 GeV, the whole mass spectra of the remaining eleven fermions are obtained within experimental errors. Deduced formulae for the masses and plot them for all the 12 fermions from t = log (μ/M_x) = 0 to t_x = 33; the GUT mass being M_x = 2.2 x 10¹⁶ GeV.

5 illus, 10 tables, 20 ref

021332   Chaudhuri J R;Barik D (Physics Dep, Katwa College, Katwa, Burdwan-713 130, Email: jprc_8@yahoo.com) : Self consistent microscopic theory of frictional ratchet in a nonequilibrium enviroment. Indian J Phys 2008, 82(11), 1577-90.

A system-reservoir microscopic model, where the associated reservoir is modulated by the external random force, is proposed to study the transport of an overdamped Brownian particle in a frictional ratchet system with an underlying periodic potential in presence of external Gaussian noise fluctuation. We then derived the analytical expression for the average velocity and study the dependence of the various system parameters and the nonequilibrium behavior of the heat bath on the transport properties of the Brownian particle. We observe that only bath modulation though it breaks the fluctuation-dissipation relation, will not produce any net current in absence of external modulation.

5 illus, 32 ref

021331   Chatterje A K;Bari M W;Chaudhury A K (Indian Centre for Space Physics (Malda Branch), , Atul Market, Malda-732 101) : Class transitions of compact objects cygnus X-1 and cygnus X-3. Indian J Phys 2008, 82(11), 1429-40.

Presents the evidences of class transitions (transitions from one type of light curve to the other) of light curves by analyzing the X-ray data obtained from IXAE and RXTE of the two compact objects Cygnus X-1 and Cygnus X-3. It is also observed from the Power Density Spectrum (PDS) that during class transitions the slope of the PDS changes but the slope remains same when there is no transition. We observe that the class transitions take place in a matter of minutes. Thus the variation in the accretion rates, which is thought to be the sole cause of the class-to-class variation, must be nearly freely falling like other black hole candidates such as GRS 1915+105.

20 illus, 39 ref

021330   Chandra Shekar N V;Sahu P C (Materials Science Div, Indira Gandhi Centre for Atomic Research, Kalpakkam-603 102, Email: chandru@igcar.gov.in) : Strong solids. Indian J Phys 2008, 82(12), 1645-54.

The adjectives hard, harder and hardest are commonly used to describe strong solids and diamond is described by the superlative-hardest! Synthesis of strong solids is of far reaching technological importance in the areas of abrasives, reactors, space flight, turbine technology etc. The quest for stronger materials leads scientists to understand the correlation between characteristics of interatomic interactions and macroscopic properties. This will have implications in the pursuit of designing new and novel materials. In this paper, the race for synthesizing a material which can dethrone diamond will be highlighted. Results on some low Z compounds, nitrides, carbides and borides of transition metals, hypothesized to be harder than diamond will be described. Efforts will be made to list down some important parameters that go into making a solid strong and then arrive at a possible ideal recipe for its synthesis.

5 illus, 2 tables, 51 ref 

021329   Bhakuni G;Bisht S (Physics Dep, Kumaun Univ, Nainital-263 002, Email: bhakugaur8@gmail.com) : Interaction of an electric charge in the radial field of a heavy dyon. Indian J Phys 2008, 82(11), 1563-75.

Considering one scalar potential and one vector potential for the interaction of an electric charge in the radial field of a dyon we have undertaken the study of equation of motion through Lagrangian and Hamiltonian formulations. The relation of magnetic field with the vector potential has been given a new interpretation which leads to an additional angular momentum in a direction transverse to radial direction which could be understood as spinning top like angular momentum. In presence of this additional angular momentum, the commutation relations between the components of total angular momentum and other related operators of the system take spherically symmetric forms. The eigen value problem of total angular momentum and Hamiltonian operator has been also analysed.

13 ref

021328   Anbarasan P M;Meenakshi G;Jeyapriya K; Subramanian M K;Subramani K (hysics Dep, Periyar Univ, Salem-636 011, Email: anbarasanpm@gmail.com) : Growth, structural and optical studies on organic single crystal imidazole. Indian J Phys 2008, 82(11), 1473-83.

Single crystal of linear optical imidazole has been grown in the laboratory by using low temperature solution growth technique. The cell parameters were determined by powder X-ray diffraction analysis. FT-Raman, FT-IR analysis were used to confirm the presence of various functional groups in the grown crystal. We have also carried out ab initio Hartee-Fock calculations & DFT levels invoking 6-31G(d,p) and 6-311G(2df.2p) basis sets and the results are compared with the experimental values. Thermal analysis was performed to study the thermal stability of the grown crystals. The crystals possess lower UV-cut off wavelength at 50 nm has confirmed by the transmittance study. Kurtz powder SHG measurement confirms the non-existence of nonlinear property of the grown crystal.

9 illus, 1 table, 17 ref

020503   Urer G;Ozdemir L (Physics Dep, Sakarya Univ, 64187, Sakarya, Turkey, Email: iozdemir@sakarya.edu.tr) : Electric dipole transitions for Mg XI (Z = 12). Indian J Phys 2008, 82(10), 1273-85.

Wavelengths, oscillator strengths and transition probabilities for electric dipole transition (E1) between 1snl (1 ≤ n ≤ 9, 0 ≤ / ≤ 3), 2s², 2s2p, 2s3s, 2s3p, 2p², 2p3s and 2p3p states for heliumlike magnesium (Mg XI) have been calculated. For these calculations multiconfiguration Hartree-Fock approximation within the framework Breit Pauli relativistic corrections have been used. Results obtained have been compared with other experimental and theoretical results.

2 tables, 43 ref

020502   Singh S;Deo Raj (Physics Dep, CCS Univ, Meerut-250 004) : Elastic cross section for electron scattering by N₂O molecule. Indian J Phys 2008, 82(10), 1265-72.

Modified absorption potential has been used to obtain the elastic differential, integral and momentum transfer cross sections for e-N₂O scattering over a wide incident energy range (100-800) eV. The independent-atom-model (IAM) alongwith partial waves has been used for the present calculations. The present results have been compared with the available experimental data and other theoretical calculations. It is found that the present values of elastic differential (EDCS) and momentum transfer cross sections are in better agreement with the experimental data than the values obtained using the unmodified absorption potential.

3 illus, 12 ref

020501   Shinde G N;Bhagat S R (NO, Indira Gandhi College, Nanded-431 603, Email: shindegn@yahoo.co.in) : Universal second order switched-capacitor filter for different Q values. Indian J Phys 2008, 82(10), 1329-37.

Aims to show how the Switched-Capacitor (SC) concept can be used to realize a wide variety of universal filter that have the advantage of compactness and tunability. This paper also explains the basic idea behind the use of the Switched-Capacitor to replace resistor in active filter. Filter using Switched-Capacitor technique overcomes a major obstacle to filter on a chip fabrication. The implementation of resistors by simulating resistors with high speed Switched-Capacitors using MOSFET is also presented. The proposed universal second order SC filter circuit implements three filter functions - low pass, band pass and high pass simultaneously in single circuit. The circuit works for narrow band to wide band filter responses with variation in Q value. The filter works better for values of Q ≥ 1.

4 illus, 4 tables, 15 ref

020500   Sharan M K;Srivastava K P;Singh V K (Physics Dep, Jai Prakash Univ, Chapra-841 301) : Amorphous semi conducting carbon thin films for carbon PV cells. Acta Cienc Indica-Chem 2008, 34(1), 127-32.

The n-type un-doped semi conducting thin films of amorphous carbon were prepared by spray pyrolysis technique using different low-cost natural materials as the amorphous carbon precursors. The obtained thin films were uniform, pinhole-free and strongly adherent to the quartz substrates. The studies dealing with the temperature dependence of conductivity revealed the semi conducting nature of the films and Halls measurements indicated their n-type conduction. The low optical band gap (between 1.03- 1.5 eV) and semi conducting nature of these amorphous carbon thin films indicated the future scope of low-cost and high efficiency carbon PV solar cells.

8 illus, 14 ref

020499   Rastogi R G;Chandra H (NO, Physical Research Laboratory, Ahmedabad-380 009, Email: hchandra@prl.res.in) : IMF and geomagnetic field : a new feature. Indian J Phys 2008, 82(10), 1247-54.

It is shown that during magnetic storms, besides the decrease of AH at low latitudes synchronous with the decrease of ring current index Dst, there are significant changes in H associated with the change of IMF-Bz. Large initial phase of the storms is associated with persistent positive Bz continuing after the IP shock. Large positive AH are observed even during the peak phase of the storms due to sudden large northward turning of IMF-Bz. This seems to be a new feature detected during the nighttime with reduced amplitude at equatorial latitudes.

4 illus, 1 table, 22 ref

020498   Raghuwanshi S K;Talabattula S (NO, Applied Photonics Laboratory, Electrical Communication Engineering De, Bangalore-560 012, Email: sanjeevkr@ece.ernet.in) : Applications of degenerate/non-degenerate modes coupling in an optical waveguide. Indian J Phys 2008, 82(10), 1373-83.

Mutual coupling between optical modes is essential in the design of integrated optic devices. Describes how optical energy couples between modes within and between optical waveguides. It has been implicitly assumed so far in the literature that the modes, once formed are unchanging except perhaps through attenuation due to absorption. In reality, simple mechanisms can lead to significant energy exchange among the various modes of a structure. Coupled mode theory describes this energy exchange and serves as the primary tool for designing optical couplers, switches and filters. Explored a coupling technique that describes the scalar electromagnetic field of a perturbed waveguide in terms of a superposition of modes of the ideal waveguide. In this paper, various applications of degenerate/non-degenerate modes coupling in an optical waveguides are discussed with examples. Degenerate coupled mode theory to analyse the co-directional waveguide coupler have been applied. The coupling period of the power is verified by Beam Propagation method.

5 illus, 1 table, 19 ref

020497   Kushwaha J K;Arora V P;Raina K K;Agarwal V K (Applied Sciences Dep, Radha Govind Engineering College, Meerut-250 004, Email: kushwahajitendra@yahoo.com) : Optical and texture property studies in a nematic liquid crystal mixture. Indian J Phys 2008, 82(10), 1385-94.

Optical (using 589 nm light source) and texture (using white light source) studies as a function of temperature have been made of a multicomponent nematogen: E47 in the temperature range 288°K to 343°K. The temperature dependence of refractive indices (n_e, n_o) and the birefringence (An) agree closely with those obtained using modified four parameter model. A linear relation is observed between birefringence (An) and the order parameter (S). The normalized polarizabilities (α_e/α, α_o/α) and order parameter have been determined at different temperatures. The microscopic order parameter and normalized extraordinary polarizability fall with rise in temperature similar to other nematic mixtures. The transition temperature measured using polarizing microscope and optical studies agree closely, and do not show a sharp transition. This transition temperature range behaviour may be due to different components in the mixture.

^ssc6 illus, 1 table, 29 ref

020496   Kumar R;Ray R P K;Tiwary S N (University Department of Physics, BRA Bihar Univ, Muzaffarpur-842 001, Email: rajesh3muz@yahoo.com) : Double photoionization of Ar (1S<. Indian J Phys 2008, 82(10), 1395-7.

Calculated the double photoionization cross section (DPICS) of Ar (1s²2s²2p²3s²3p²) ^s1S°₀ employing the configuration interaction (Cl) wave function for the ground state and Brauner, Briggs and Klar (BBK) double continuum wave function (DCWF) for the final state involved in the electric dipole transition matrix element exactly in the same as we did in our earlier work (S N Tiwary and R Kumar Indian J. Phys. 78 1095 (2004)). Comparison is made with other available experimental and theoretical results. Our present calculated result is encouraging.

1 illus, 13 ref

020495   Khare P K;Bangre G;Mishra P;Mishra J (Postgraduate Studies and Research in Physics and Electronics Dep, Rani Durgavati Univ, Jabalpur-482 001) : Exploration of space charge behaviour of polyvinyl carbazole using measurement of thermally stimulated discharge current. Indian J Phys 2008, 82(10), 1301-8.

Measurements of thermally stimulated depolarization currents (TSDC) have been employed to investigate the space charge behaviour and molecular motion in polyvinyl carbazole (PVK) foil samples at different poling fields and temperatures. One relaxation peak was observed around 70-110°C. It was found that with increasing applied electric field the order of peak current increases and peak shifts towards lower temperature side. The order of current for samples poled at 50°C was higher than the samples poled at 60°C. The activation energy decreases with the increase in poling field and temperature. The current maxima occuring above the polarizing temperature, have distributed relaxation times. The analysis of the results suggest that intense charge trapping in surface and bulk traps and of the injection of carriers from electrodes under strong field at near surface region created by heterocharge.

12 illus, 12 ref

020494   Janarthanan S;Kishore Kumar T;Selvakumar S; Pandi S;Sagayaraj P;Anand D P (Physics Dep, Presidency College, Chennai-600 005, Email: dpremanand@yahoo.co.in) : Investigation on the mechanical, dielectric and photoconductivity properties of N-methyl urea NLO single crystals. Indian J Phys 2008, 82(10), 1287-92.

Single crystal of N-Methyl Urea (NMU), an organic nonlinear optical material was grown by slow evaporation technique from methanol as solvent. The grown crystals were characterized by single crystal XRD, microhardness, dielectric and photoconductivity studies. The non-centrosymmetric space group of the crystal was elucidated by single crystal XRD analysis. The Vickers Hardness Number (VHN) values of NMU suggest that the mechanical strength of (110) plane is harder than (100) and (011) planes. It was observed from the dielectric studies that the dielectric constant and dielectric loss of NMU sample has high values at low frequency and it remains almost constant at high frequency range. Photoconductivity studies of NMU crystal revealed positive photoconducting nature of the sample.

5 illus, 10 ref

020493   Ghosh D;Deb A;Haldar P K;Guptaroy S (Nuclear and Particle Physics Research Centre, Physics Dep, Jadavpur Univ, Kolkata-700 032, Email: dipakghosh_in@yahoo.com) : Fluctuation and fractal characteristics of ring like and jet like events produced at SPS energies. Indian J Phys 2008, 82(10), 1339-71.

The study of pion fluctuation patterns in terms of Scaled Factorial Moments (SFMs) in one dimensional space (pseudorapidity and azimuthal angle) for ring like and jet like events in ³²S-AgBr interactions at 200 A GeV energy. The study reveals a clear signal of intermittency in the density fluctuations for both types of events. It is however observed that, strong intermittent pattern is revealed only in jet like events. The behaviors of anomalous fractal dimensions and generalized fractal dimensions reflect the self similar cascade mechanism. Moreover, the non-thermal phase transition is seen only in jet like events for pseudorapidity variable and in ring like events for azimuthal angle variable. The multifractal specific heats and entropy have also been calculated.

19 illus, 16 tables, 42 ref

020492   Ganesh V;Kishan Rao K (Physics Dep, Kakatiya Univ, Warangal-506 009, Email: kishankotte@yahoo.co.in) : Surface and hardness studies on as-grown {100} faces of zinc (tris) thiourea sulphate crystals. Indian J Phys 2008, 82(10), 1293-1300.

Single crystals of zinc (tris) thiourea sulphate are grown at 30°C by slow evaporation method. Surface studies have been carried out on a number of {100} faces of these crystals. Typical striations are observed on these faces, mostly they are oriented parallel to shorter face of the crystals. In very few cases striations parallel to the longer face are also observed. These studies suggest that the growth occurs by 2D nucleation. Further chemical etching technique has been employed to study dislocations in these crystals. The dislocations are randomly distributed, they are mainly observed at the edges of the crystal. The average dislocation density is about 4 x 10⁵/cm². Mechanical characterization has been done by Vicker's microhardness technique. The work-hardening index number (n) for these crystals is about 1.9 which is close to theoretically expected value of 2. The hardness studies made on about 50 crystals suggest that hardness (H_v) value is about 76 ± 1 kg/mm².

7 illus, 1 table, 17 ref

020491   Dhokne R J;Sangawar V S;Chikhalikar P S;Thool V S;Ubale AU;Junghare A R (P G Dep of Physics, Govt. Vidarbha Institute of Science and Humanities, Amravati-444 604, Email: raginidhokne@yahoo.co.in) : Structural characterization and electrical conductivity of naphthalene doped polyblend films of polystyrene (PS) and polymethyl methacrylate (PMMA). Indian J Phys 2008, 82(10), 1309-18.

A thermally stimulated depolarization conductivity (TSDC) investigation in short circuit configuration have been carried out on physical blend of polystyrene (PS) and polymethyl methacrylate (PMMA) with composition 80:20 and naphthalene doped blend (PS : PMMA). The films of undoped blend and naphthalene doped blend were prepared by isothermal evaporation technique. Thermoelectrets of these films are formed at polarizing temperature 343 K and different polarizing field (Ep) 3, 5, 10,15 kV/cm. The depolarization conductivity recorded as a function of temperature and polarizing fields were characterized by two well defined peaks. The first peak is obtained at 338 ± 5 K due to the low temperature β relaxation and second peak at 363 ± 5 K may be due to the higher temperature a relaxation. The magnitude of peak conductivity increases linearly with the polarizing field.

5 illus, 2 tables, 14 ref

020490   Borse R Y;Garde A S (Thin and Thick Film Laboratory, Electronic Science Dep, M S G College, Malegaon Camp, Malegaon, Dist-Nasik-423 105, Email: ratanborse@yahoo.co.in) : Effect of firing temperature on electrical and structural characteristics of SnO₂ thick films. Indian J Phys 2008, 82(10), 1319-28.

Tin-oxide (SnO₂) thick films were fabricated by using standard screen-printing technology on alumina substrates. The films were dried and fired at different firing temperatures for 30 minutes. The variation of D.C. resistance of thick films was measured in air as a function of temperature. The SnO₂ films studied were showing decrease in resistance with increase of temperature, showing semiconducting behaviour. The resistivity (p), activation energy, and temperature coefficient of resistance (TCR) are evaluated at different firing temperatures. The X-ray diffraction (XRD) patterns of the films indicate the presence of tetragonal SnO₂ phase. The elemental analysis was confirmed by EDAX spectra. The surface morphological study of the films was analyzed by Scanning Electron Micrograph (SEM). The microstructure of the films was porous resulting from loosely interconnected small crystallites.

6 illus, 2 tables, 43 ref

019429   Zambare A P;Sai Prasad A S;Natrajan V; Nageswara Rao B;Murthy K V R (Physics Dep, Agasti Arts, Commerce & D R Science College, Akole, Tal-Akole, Dist- Ahmednagar-422 601, Email: avinashzambare2003@yahoo.co.in) : Thermoluminescence studies of BaMgAl₁₀O₁₇ doped with Eu phosphors. Indian J pure appl Phys 2009, 47(6), 453-5.

BaMgAl₁₀ O₁₇:Eu, phosphors have been synthesized in air atmosphere by high temperature solid state reaction. Two well defined thermoluminescence (TL) glow peaks are shown at 180 and 330°C under gamma irradiation. The TL emission spectra of samples reveal two emission peaks at 617 and 895 nm. These changes are probably due to electronic charges and sizes of Eu^{3+ dopant ions.}

019428   Yerpude A N;Puppalwar S P;Dhoble S J;Animesh Kumar (NO, Kamla Nehru College, Sakkardara Square, Email: sjdhoble@rediffmail.com) : Effect of Mg and P ions on photoluminescence characteristics of Li₂SO₄: Cu phosphor. Indian J pure appl Phys 2009, 47(6), 447-9.

Synthesis of the Li₂SO₄: Cu phosphor has been done by using wet chemical method The XRD technique shows the crystalline nature of the prepared material. Photoluminescence (PL) emission spectra of Li₂SO₄: Cu phosphor shows the strong prominent peak at 387nm in the violet region of the visible spectrum due to the transition of 3d^{10↔3d94s1 of Cu+ ion. The increase in photoluminescence of Li₂SO₄:Cu by co-doping with Mg and P has been studied.}

019427   Yadav R S; Khan A F;Harish Chander;Haranath D;Yadav A;Sharma A K;Chawla S (NO, National Physical Lab, Dr. K.S. Krishnan Road, Email: santa@nplindia.org) : Development of plasma display panel phosphors at National Physical Laboratory, New Delhi. Indian J pure appl Phys 2009, 47(6), 300-401.

Plasma Display Panel (PDP) phosphors of three primary colours red, green and blue (RGB) have been developed for application in 50" HDPDP panel at SAMTEL. Three phosphors one each for red, green and blue was zeroed down. Synthesis processes by high temperature solid state reaction were optimized to achieve maximum quantum efficiency. Also synthesizes RGB nanophosphors by autocombustion method and compared with bulk RGB phosphor. Photoluminescence emission characteristics under VUV (172 nm) and UV (250 nm) excitation of the RGB phosphors show their suitability for PDP applications.

019426   Upender G;Kamalaker V;Vardhani C P;Chandra Mouli V (Glassy Materials Research Lab, Physics Dep, Osmania University, Hyderabad-500 007, Email: vorucm90@yahoo.com ) : ESR, infrared and optical absorption studies of Cu<. Indian J pure appl Phys 2009, 47(8), 551-6.

ESR, IR and optical absorption studies on 60B₂O₃-10TeO₂-(30-x)MO-xPbO (where M=Zn, Cd) glasses containing Cu²⁺ spin probe have been carried out. The IR results prove the distribution of trigonal bipyramids (TeO₃) which determines the network and the distribution of borate triangles (BO₃) and borate tetrahedral (BO₄) groups. Structural changes take place with variation of PbO content in BTZP and BTCP series. ESR results show that the g<124><124> > g⊥ indicating that the Cu^{2+ ion is in tetragonal distorted octahedral site and its ground state is d_x2-y2. There are considerable changes in g<124><124>, g⊥ and A<124><124> values with the increasing concentration of PbO in both BTZP and BTCP glass systems. The optical absorption spectra results show that the absorption peak of Cu2+ is a function of composition. The observed optical absorption peak of Cu2+ has been found to be maximum at 813 nm for x=30 mol% of PbO content. Bonding parameters are calculated from both optical and ESR data. All these variations clearly indicate the structural changes in the present glass systems with varying PbO content.}

019425   Tyagi S K;Park S R;Tyagi V V;Anand S (Geothermal Energy Research Centre, Korea Institute of Energy Research, PO Box 103, Yuseong-gu, Daejeon 305-343, South Korea, Email: sudhirtyagi@yahoo.com) : Economical and thermal optimization of possible options to control visible plume from wet cooling towers. Indian J pure appl Phys 2009, 47(8), 597-608.

Economic study has been done for the heat pumps, biogas and solar collectors along with the phase change materials (PCM) storage and the results have been compared for various costs. The different combinations and options for the heating and cooling requirements, the heating capacities and the comparisons of different costs are studied in detail. It has been found that all the costs are much lesser for a solar collector system followed by the biogas plant and the heat pump systems. On the other hand, all the costs are found to be the highest in the case of an air cooled geothermal heat pump system, while it is reverse in case of the water cooled solar collector system.

019424   Tiwari A;Khanna K N (Physics Dep, VSSD College, Kanpur, Email: knkhanna@rediffmail.com) : Pair correction function for square-well fluids. Indian J pure appl Phys 2009, 47(8), 582-5.

The analytical forms of the modified pair correlation function at contact for square-well fluids have been proposed. These expressions can be employed to determine thermodynamical properties of square-well fluids and are simple, easily computable and accurate over wide range of densities.