000034   Muraliji D;Sekar S;Dhanalakshmi A;Ramkumar A R (P G & Research, Dep of Phys, National College, Tiruchirapalli-1) : Internal pressure and free volume in vanillin through ultrasonic measurements. J pure appl Ultrasonics 2002, 24(3-4), 68-70.

Vanillin is one of the popular flavoring and perfuming materials. Levopoda, which is used as a drug for Parkinson's disease, is synthesised from vanillin. Study of internal pressure and free volume yield valuable information regarding molecular interactions in solutions. The parameters of aqueous solutions of vanillin with different concentrations at temperatures ranging from 303K to 328K have been determined through ultrasonic measurements. Molecular interactions in these solutions have been analysed on the basis of variations in their internal pressure and free volume with concentration at various temperatures.

2 illus, 1 table, 6 ref

000033   Muraliji D;Sekar S;Dhanalakshmi A;Ramkumar A R (P G & Research, Phys Dep, National College, Tiruchirapalli-14) : Study of ultrasonic velocity and thermodynamic parameters of vanillin. J pure appl Ultrasonics 2002, 24(3-4), 63-7.

Vanillin is one of the popular flavoring and perfuming materials. Levopoda, a drug for Parkinson's disease is synthesized from vanillin. Ultrasonic velocity and thermodynamic parameters of aqueous solutions of vanillin at different concentrations have been studied using an ultrasonic interferometer at various temperatures ranging from 303K to 328K. Acoustical impedance, adiabatic compressibility, intermolecular free length, Rao's constant, Wada's constant, relative association and available volume of these solutions have been computed from the measurements of their ultrasonic velocity, density and viscosity. Their acoustical relaxation time, ultrasonic attenuation, Lennard Jones potential and Van der Waal's constant have also been computed. Molecular interactions in these solutions have been analysed on the basis of non-linearity between these parameters and solute concentrations at various temperatures.

4 illus, 2 tables, 7 ref

000032   Misra D K;Tiwari R S;Srivastava O N (Phys Dep, Banaras Hindu Univ, Varanasi-221 005) : Devitrification of rapidly quenched Al-Cu-Ti amorphous alloys. Bull Mater Sci 2003, 26(5), 553-8.

X-ray diffraction, transmission electron microscopy and differential scanning calorimetry were carried out to study the transformation from amorphous to icosahedral/crystalline phases in the rapidly quenched Al₅₀Cu₄₅Ti₅ and Al₄₅Cu₄₅Ti₁₀ alloys. The formation and stability of amorphous phase in Al₅₀Cu₄₅Ti₅ and Al₄₅Cu₄₅Ti₁₀ rapidly quenched alloys have been studied. The DSC curve shows a broad complex type of exothermic overlapping peaks (288-550°C) for Al₅₀Cu₄₅Ti₅ and a well defined peak around 373°C for Al₄₅Cu₄₅Ti₁₀ alloy. In the case of Al₅₀Cu₄₅Ti₅ alloy amorphous to icosahedral phase transformation has been observed after annealing at 280°C for 73 h. Large dendritic growth of icosahedral phase along with α-Al phase has been found. Annealing of Al₅₀Cu₄₅Ti₅ alloy at 400°C for 8 h results in formation of Al₃TI Type phase. Al₄₅Cu₄₅Ti₁₀ amorphous alloy is more stable in comparison to Al₅₀Cu₄₅Ti₅ alloy and after annealing at 400°C for 8 h it also transforms to Al₃Ti type phase. However, this alloy does not show amorphous to icosahedral phase transformation.

6 illus, 1 table, 18 ref

000031   Lipare A Y;Vasambekar P N;Vaingankar A S (Post Graduate Electronics Dep, Shivaji Univ, Kolhapur-416 004) : A.c. susceptibility study of CaCl₂ doped copper-zinc ferrite system. Bull Mater Sci 2003, 26(5), 493-7.

Polycrystalline soft ferrites, Zn_xCu_1-xFe₂O₄ (x = 0.30, 0.50, 0.70, 0.80 and 0.90), doped with controlled amount of calcium chloride (CaCl₂) were prepared by standard ceramic route and studied for a.c. susceptibility. X-ray diffraction studies of the compositions reveal formation of single-phase cubic spinel. The values of lattice constant increase as doping percentage of CaCl₂ increased from 0.01% to 0.05% and afterwards decrease slightly. The presence of chlorine ions is confirmed by absorption peak in far IR spectra near 650 cm^-1 for all the samples. The variation of a.c. susceptibility with temperature shows the existence of single domain structure for x = 0.3 and exhibits transition from single domain to multidomain structure with increased Ca²⁺ contents from 0.01 to 0.1%. The composition, x = 0.5, shows multidomain structure independent of Ca²⁺ content. The samples for x = 0.70, 0.80 and 0.90 show paramagnetic behaviour at and above room temperature.

5 illus, 1 table, 32 ref

000030   Khodier S A (National Institute for Standards, Optical Metrology Department, , P O Box 136, Giza, 12211 Egypt) : Measurement of wire diameter by optical diffraction. J Optics 2003, 32(1), 19-25.

A combined interference and diffraction pattern, in the form of equidistant interference fringes, resulting from illuminating a vertical metallic wire by a laser beam is analyzed to measure the diameter of four standard wires. The diameters range from 170 to 450 μm. It is found that the error in the diameter measurements increases for small metallic wires and for small distances between the wire and the screen due to scattering effects. The intensity of the incident laser beam was controlled by a pair of sheet polaroids to minimize the scattered radiation. The used tehcnique is highly sensitive, but requires controlled environmental conditions and absence of vibration effects. The expanded uncertainty is calculated and found to decrease from ±1.45 mm for the wire of nominal diameter of 170 μm, to ±0.57 μm for the diameter, 450 μm.

2 illus, 1 table, 16 ref

000029   Kedar Singh;Saxena N S (Physics Dep, Univ of Rajasthan, Jaipur-302 004) : Kinetics of Ge₂₀Se_80-xAs_x (x = 0, 5, 10, 15 and 20) in glass transition region. Bull Mater Sci 2003, 26(5), 543-6.

The results of differential scanning calorimetric (DSC) measurements on Ge₂₀Se_80-xAs_x (x = 0, 5, 10, 15 and 20) system with the specific aim of investigating the effect of heating rate and composition on glass transition temperature have been discussed. The results indicate that the glass transition temperature (T_g) is dependent both on the heating rate and composition. The glass transition activation energy (E_t) and heat absorbed in glass transition region (ΔH) are higher for Ge₂₀Se₆₅As₁₅ as compared to the values of other compositions of arsenic. An effort has also been made to develop an empirical model for the composition dependence of ΔH. A good agreement has been observed between the experimental values and the results of model calculation.

4 illus, 1 table, 15 ref

000028   Govindarajan R (Fluid Dynamics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560 064) : Surprising effects of minor viscosity gradients. J Indian Inst Sci 2002, 82(2), 121-7.

It is shown that a small stratification of viscosity in the flow through a channel, if carefully located to overlap the production layer of disturbance kinetic energy, can produce a large effect on flow stability. Some implications are discussed.

8 illus, 18 ref

000027   Das N C et al (Spectroscopy Div, Bhabha Atomic Research Centre, Mumbai-400 085) : Development of angle resolved photoelectron spectroscopy beamline at Indus-1 synchrotron radiation source. J Optics 2003, 32(1), 27-35.

A beamline for angle resolved photoelectron spectroscopy (ARPES) using Indus-1 synchrotron source has been recently commissioned at the Centre for Advanced Technology, Indore. The optical system for the beamline consists of a pre-focussing toroidal mirror, 1.4 meter toroidal grating monochromator (TGM-1400) and a post-focussing toroidal mirror to cover the spectral region of 40 Angstrom to 1000 Angstrom. The beamline is coupled with an ARPES experimental station which houses the indigenously built electron analyser, sample manipulator, LEED/Auger probes, sputter etch Ar ion gun, sample load and lock facility. The photoemission spectra of some solid samples which have been recorded through this beam line have been presented.

6 illus, 5 ref

000026   Biering I;Larsen K;Garp T;Christensen D H; Bender Koch C;Waage Jensen P;Faurskov Nielsen O (Chem Institute, University of Copenhagen, Universitetsparken, 5, DK-2100 Copenhagen, Denmark) : NIR-FT micro Raman spectroscopy of the meteorite Axtell. Asian Chem Lett 2003, 7(2), 99-105.

NIR-FT-Raman spectroscopy was used to characterize the chemical composition of the meteorite Axtell. This is a carbonaceous chondrite of the CV3 type. The exciting laser wavelength was 1064 nm. Various sites of the surface of this inhomogeneous meteorite were investigated by use of a Raman microscope. Spots of different colours differed in the chemical composition. The minerals pyroxene and olivine were identified. The carbon containing regions showed bands characteristic for ordered (G-band) and disordered (D-band) graphite. These bands were compared to Raman spectra of the carbon modification known as shungite, Type I found on the earth. The D-band is activated by disorder in the structure of sp²-hybridised carbons. The appearance of the D-band depends on the phonon dispersion curves for the two materials. Phonon dispersion curves reflect basically the overall structure of a material, indicating a similarity between the carbon structures of the meteorite from space and shungite from the earth. As expected, the Raman shift of the D-band was changed when an exciting wavelength at 514,5 nm was used.

7 illus, 16 ref

000025   Bajpai R;Sharma S;Vastal V K;Chandra B P (Dep of Postgraduate Studies and Res Phys, Rani Durgavati Univ, Jabalpur-482 001) : Photoplastic effect in polycarbonate using microhardness measurements. Bull Mater Sci 2003, 26(5), 537-41.

Vickers microhardness indentation technique has been employed to detect the photoplastic effect in the transparent polycarbonate specimens in darkness and under mercury illumination. For low applied loads, the hardening of specimens under illumination confirms the positive photoplastic effect that causes illumination-induced increase of crosslinking (in polymer). For high applied loads the positive photoplastic effect decreases as the level of microhardness decreases.

5 illus, 8 ref

000024   Bajpai P K;Ratre K;Pastor M;Sinha T P (School of Pure and Applied Physics, Guru Ghasidas Univ, Chattisgarh-495 009) : Preparation, characterization and dielectric behaviour of some yttrium doped strontium stannates. Bull Mater Sci 2003, 26(5), 461-4.

Samples of Sr_(1-3x/2)Y_xSnO₃ are prepared by usual solid state reaction route. X-ray diffraction studies confirm the formation of single cubic perovskite single phase. The dielectric constant and dielectric loss at 1 kHz were measured in the temperature range from room temperature up to ≅ 150°C. The dielectric constant decreases and losses increase with increased yttrium content in the samples. The percentage porosity and unit cell parameters are also calculated for the samples.

5 illus, 2 tables, 6 ref 

000023   Ashok Kumar;Khan M R;Choudhari N K (Ultrasonics Section, National Physical Laboratory, New Delhi-110 012) : Improvement in time interval measurement of ultrasonic wave propagation. J pure appl Ultrasonics 2002, 24(1), 6-10.

A more accurate method for ultrasonic time interval measurement is described. Problems associated with measurement and its causes are also discussed. Corrective measures are suggested through an additional circuit and implemented to avoid effect of noise and circuit components. The modified circuit has special significance in low frequency measurements.

9 illus, 1 table, 5 ref

000022   Arya S K;Sharma A K;Agarwala R A;Kaler R S; Kamal T S (Electronics and Communication Engineering Dep, National Institute of Technology, Jalandhar-144 011) : Dispersion effects for a four component-lightwave source in mm-wave fiber radio systems. J Optics 2003, 32(1), 5-11.

An improved analysis of dispersion effects on a lightwave source with four components of different angular frequencies corresponding to the desired millimeter (MM)-wave frequency has been reported. For optical subcarrier transmission, it is proposed to use an actively Mode Locked Laser (MLL) as an optical source. The MM-wave power penalty due to second, third and fourth order dispersion parameters has been obtained. It has been shown that the dispersion induced power penalty lies within the range of 3 dB to-0.5 dB at the linear chirp of 0.13π and transmission distance up to 10 Kms including the effect of higher-order dispersion (HOD) parameters. Further, it has been observed that dispersion induced power penalty increases with the increase in the transmission distance due to the influence of HOD terms.

4 illus, 14 ref

023060   War T A;Chandan A;Devi R;Bharti A;Khosa S K (Physics Dep, Jammu University, Jammu-180 006) : Microscopic study of low spin yrast levels in even-even krypton isotopes in the variation ater projection approach. Indian J Phys-Pt B 2003, 77(5), 465-71.

Variation after projection (VAP) calculations in conjuctions with Hartree-Bogoliubov (HB) ansatz have been carried out for A=74-82 krypton isotopes. In this framework, the yrast spectra with J^π≤16⁺, B(E2) transition probabilities, quadrupole (β₂) deformation parameter have been obtained. The results of the calculation give an idication that it is important to include the hexadecapole-hexadecapold component of the two-body interaction for obtaining various nuclear structure quantities in Kr isotopes. Besides this the yrast spectra in ^76-78Kr isotopes arise from two intrinsic states.

2 illus, 4 tables, 33 ref

023059   Vasanthi G;Krishnaswamy S (Physics Dep, Lady Doak College, Madurai) : Dipole moment in TIM alpha/beta fold proteins. Indian J Biochem Biophys 2003, 40(3), 194-202.

TIM proteins of α/β class as given in SCOP database were taken for dipole moment analysis. In all, 32 structures were analyzed for their dipole moment contributions. Representative structures from 20 super families in the α/β fold, with different enzyme functions and 12 protein domains of TIM family in TIM super family were considered. The active sites of these proteins are located on the C-terminal side of the β-strands. The molecules of same α/β fold, but differing in their functionality also showed a common electrostatic field pattern along the barrel axis and had the dipole moment along the barrel axis and towards C-terminal end of the β-strands. However, it is observed from our calculations that the dipole moment direction is possibly a consequence of the structural fold, with distribution of charges playing a modulatory role, and does not contribute to the location of active site. It has been shown that apart from the commonly held view of the role of the α helical dipole moment, the β-sheets in the barrel can also have a considerable dipole moment contribution. Taken together with dipole moment analysis on integral membrane proteins this suggests the need to examine the role of dipole moment in the case of especially β sheets forming barrels.

2 illus, 6 tables, 48 ref

023058   Thomas M;Ghosh S K;George K C (Physics Dep, S B College, Changanacherry-686 101 Kerala) : Dieliectric and impedance spectroscopic studies on nanophase silver orthophosphate. Indian J Phys-Pt B 2003, 77(5), 425-31.

Nanphase Ag₃PO₄ was prepared by chemical precipitation for three reactant concentrations (0.015 mol. L^-1, 0.01 mol, L^-1, 0.005 mol L<6>-1). Room temperature impedance spectroscopic analysis of the samples was carried out using the 'sand witch' geometry. The experimental data for the samples represented by the complex plane diagrams showed three semicircular arcs similar to that of polycrystalline, ionic conductors. Dielectric constant (ε) and loss tangent (tanδ) were measured as a function of temperature (300 K-500 K) at different frequencie (100 KHz-10MHz). Space chrge polarization effects are found to be prominent at low frequencies and at high temperatures, characteristic of nanphase materials. Reactant concentration plays a role in determining the electrical properties of nanophase Ag₃PO₄.

6 illus, 2 tables, 22 ref

023057   Thokale R N;Dongare M B (Holography Lab, Physics Dep, Shivaji Univ, Kolhapur-416 004) : Holographic interferometry for measurement of Poisson's ratio of metals. J Optics 2002, 31(1), 37-42.

Double exposure holographic interferometry (DEHI) technique can be used to study the change in object shape, such as an object deformation or displacement due to applied stress from pressure, load, heat, electric or magnetic field. It can also be used to contour an object. since the determination of Poisson's ratio. DEHI method has been employed to measure Poisson's ratio of Nickel, Lead and Titanium metals. It is noticed that the values of calculated Poisson's ratio using DEHI technique are in close agreement with the standard values of Poisson's ratio for these metals.

3 illus, 1 table, 18 ref

023056   Singh M P;Ajay Govind;Gupta B R K (Physics Dep, G B Pant University of Agriculture & Technology, Pantnagar-263 145 Uttranchal) : Role of CuO chains on the supercurrent density in bilayer cuprate superconductors. Indian J Phys-Pt B 2003, 77(5), 441-7.

Studies the role of CuO-chains on supercurrent density in bilayered cuprate superconductors. For this purpose, a tight binding model Hamiltonian that includes various intra and inter-bilayer interactions alongwith contributions of Josephson-like tunneling of Cooper pairs from bilayer of CuO₂ planes to CuO-chains and vice-versa as well as single particle hopping between CuO₂ bilayer to CuO-chains in the form of the bilayer chain interaction within a unit cell is considered. The situation considered is equivalent to a Josephson's coupled SNS junction. In the superconducting state, the CuO₂ bilayer serves as superconducting electrode and CuO-chains as one dimensional metal under fully oxygenated overdoped state sandwitched between these two electrodes as in the case of YBa₂Cu₃O₇ bilayer system and there is always a possibility of Cooper pairs to tunnel from one bilayer CuO₂ planes to other bilayer iva CuO-chains. To drive the expressions for the superconducting order parameter, carrier density andsupercurrent density, one relies on meanfield Green's funciton equations of motion calculations within the BCS formalism. The numerical calculations show that in bilayer cuprates, the supercurrent density depend on the interlayer pair tunneling between the CuO₂ planes, hopping matrix element (t_ch) for chains and the hopping of single particle from bilayer to chains. Finally, compares these results with the existing experimental findings.

3 illus, 36 ref

023055   Singh K Y;Gupta B R K (Physics Dep, G B Pant University of Agriculture and Technology, Pantnagar-263 145) : Analysis of temperature dependence of thermal expansion in CaSiO₃ and (Mg_1-xFe_x) SiO₃ perovskites. Indian J Phys-Pt B 2003, 77(5), 495-7.

Calculates the values of CaSiO₃, MgSiO, (Mg_0.9Fe_0.1) SiO₃ perovskites under high temperature and high pressure using the Shanker equation os thermal expansivity. The results obtained are found to be in close agreement with the recent experimental P-V-T data for the solids under study. It has been concluded that the Anderson-Gruneisen parameters varies significantly at high temperature and the results are modified. The method has been found to be useful for predicting the volumes of the solids under high temperature.

2 tables, 12 ref

023054   Singh J P;Babbar N K;Hari Krishan (NO, National Physical Laboratory, Dr. K S Krishnan Road, New Delhi - 110 012) : Feasibility study of air-conditioner using hydrogen hybride system. Indian J Cryogenics 1997, 22(2), 48-52.

Hydrogen-hydride heating/cooling device is an absorption refrigeration system using a solid and gas pair as its working substance. It has desirable features and characteristics in comparison to the conventional systems. The percent concentraion of hydrogen at different temperatures and pressures is a characteristic property of the hydride, which is utilised in this absorption refrigeration system. The system consists of two types of hydrides. One works at high temperature and the other at a comparatively lower temperature. Any heat source can be used to supply energy to the system. But to develop a proto type model an electric power for producing dry steam, superheated to a temperature of 110° C at atmosphere pressure is being employed. This dry steam is used to heat the first type of hydride. This liberates hydrogen form the first hydride which is absorbed by the second type of hydride. Heat is produced during the absorption of the hydrogen, which is removed by the cooling water. The next step is to cool the first hydride, which absorbs hydrogen back from the second hydride. During the process second hydride becomes cool and absorbs heat and cools the water which acts as a secondary refrigerant. This cold water cools the air which is blown through an air blower of the conventional fan-coil unit placed in the air-conditioned space. One of the most important part of such a system is an electronic sequential timer which operates and controls the timings and fluid flows in the different circuits of the system. Describes the conceptual design for the development of such an air-conditioner to test the feasibility of this new kind of technology for the purposes of space air-conditioning.

4 illus, 8 ref

023053   Singh J P (Department of Management Studies, Indian Institute of Technology, Roorkee-247 667 Uttranchal) : On the impact of noise on quantum chaos. Indian J Phys-Pt B 2003, 77(3), 303-13.

Using the Langevin formalism, the impact of damping, noise and potential gradient on a particle in a double well potential has been studied in the quantum regime and results compared with the h→0 classical limit. It has been shown that the effects of damping and noise on the system are complementary in so far as the reduciton of chaocity of the system is concerned, both opposing the potential drived force. Further, as regards the inducement of quantum chaos, quantum tunneling effects are shown to dominate. The limitations of the study in particular, the efficacy of the Ehrenfest's theorem in the classical regime are also explored.

6 illus, 60 ref

023052   Singh G S;Jain P K;Narasimham V M L (Advanced Optical Processing Div, Central Scientific Instruments Organization, Sector 30 Chandigarh-160 030) : Design considerations of a high magnification compact size zoom lens: choice of a zoom type. J Optics 2002, 31(1), 17-27.

The paraxial thin lens design of a large magnification compact size zoom lens has been described. Various types of four-component mechanically compensated zoom lenses are compared for their suitability to meet the specific requirements. It has been shown that Type IV Zoom lens is a best choice for this purpose

4 illus, 4 tables, 8 ref

023051   Sharma S;Bhalla G L; (Department of Physics & Astrophysics, University of Delhi, Delhi-110 007) : Effect of water of YBa_2-xSr_xCu₃O_7-δ. Indian J Cryogenics 1997, 22(4), 120-2.

Stability of YBa_2-xSr_xCu₃O_7-δ (0<60>x<60>0.6) in water has been examined by using R-T measurements, x-ray diffraction and iodometric technique. Preliminary studies indicate that Sr-doped samples degrade slower than the undoped YBa₂Cu₃O_7-δ. However, the rate of degradation increases with dopant concentration.

1 illus, 1 table, 26 ref

023050   Sen Gupta N D (NO, Tata Insitute of Fundamental Research, Mumbai-400 005) : On the monopole and quantization of charge. Indian J Phys-Pt B 2003, 77(5), 473-6.

The motion of an electron in the magnetic field of a monopole is investigated, both from the Dirac and the Klein-Gordon equations. It is shown that the single-valuedness of the angular factor of the wave function in both the cases lead to the quantization of charge.

6 ref

023049   Sarah P;Suryanarayana S V (NO, C V R College of Engineering Vastunagar, Mangalpalli (V), R R District-501 510 Andhra Pradesh) : Magnetic properties of diphasic composites of LiF₅O₈-BaTiO₃. Indian J Phys-Pt B 2003, 77(5), 449-52.

Diphasic composites of ferrimagnetic LiFe₅O₈ and ferroelectric BaTiO₃ have been synthesized. Room temperature magnetic moment of these composites has been measured in varying DC magnetic fields. From the hysteresis loops, values of coercivity, saturation magnetization and magnetic loss have been obtained. Saturation magenetization and magnetic loss are found to be low. A model is suggested to explain the various magnetic properties of these composites.

5 illus, 20 ref

023048   Sahay P P;Jha S;Shamsuddin M (Physics Dep, National Insitute of Technology, Silchar-788 010 Assam) : Growth and characterization of CdSe films prepared by thermal evaporation technique. Indian J Phys-Pt B 2003, 77(5), 459-63.

CdSe thin films of varying thickness have been prepared by the thermal evaporation technique under a vaccum better than 2 x 10^-5 torr. The films thus prepared have been characterized by measuring sheet resistance/conductivity in the temperature range 300-450 K. The conductivity studies show that the films of thickness 2000 and 3000 A have grain boundary limited conduction in the temperature range 300-45- K, whereas film (1000 A) exhibits grain-boundary limited conduciton in the temperature range 300-450 K and conduction via deep energy level connected with a lattice defect in the range 375-450 K. Further, during heating cycle the films (4000 and 5000 A) exhibit differentenergies in two different temperature regions, indicating thereby two deep energy levels reponsible for conduciton.

3 illus, 11 ref

023047   Rekhi S;Bhalla G L;Trigunayat G C (Dept. of Physics and Astrophysics, University of Delhi, Delhi-110 007) : A co-ordinate mirostructural and morphological investigation on the stability of YBCO with water. Indian J Cryogenics 1997, 22(2), 57-68.

A comprehensive investigation of the stability of YBCO samples in water has been carried out, involving XRD, oxygen content estimation, susceptibility measurements, SEM and EDAX studies. The experimental results derived drom the respective studies are found to mutually compatible. Formulation of various amorphous and crystalline products, microcraks, network of macrocracks and layer fragmentation has been observed. The degradation of the material in water has been found to proceed somewhat layer by layer towards to interior of material. An efficacious model for the mechanism of degradationis suggested, involving cation adn anion exchanges within the material, followed by local colapsing of unit cells, creation of stacking faults and structural expansion along c-dimension. It statisfactorily accounts both for the present and the past experimental results.

13 illus, 2 tables, 33 ref

023046   Rahnama F;Sarkar S;Basuray A (Optics & Opto-Electronics Section, Applied Phys Dep, Univ Coll of Technol, Univ of Calcutta, 92, A.P.C. Road, Calcutta-700 009) : Observation of time periodic photoinduced birefringence in a plastic film of azo dyes. J Optics 2002, 31(4), 181-90.

The photoinduced birefringence in a transient oscillatory mode, in the case of a double-component azo-dye-doped PVA film, is reported. The temporal oscillatory profiles observed are of appreciable amplitude and frequency, suggesting the complexity in domain of various mechanisms probably by the virtue of the film's regime. The experimental results are presented with some qualitative explanation of the physical phenomena behind it.

5 illus, 11 ref

023045   Purohit G;Joshi G C;Mehata M S;Tripathi H (Centre of Energy Studies, Indian Institute of Technology, New Delhi-110 016) : Spectroscopic studies of 8-hydroxyquinoline (8-hq) doped in polymeric matrices. J Optics 2002, 31(1), 1-7.

The absorption and emission spectra of 8-hydroxyquinoline (8-HQ) in thin films of PMMA (polymethyl methacrylate) and PVA (polyvinyl alcohol) have been reported. The extents of poling have been estimated by changes in absorption and emission spectra, which appear mainly in the form of shifts in the position of band maxima, absorption coefficients and emission intensities under same geometrical condition. This understanding is necessary for the development and design of second-order nonlinear optical polymeric devices.

4 illus, 1 table, 13 ref

023044   Patil K D (NO, B. D. College of Engineering, Sewagram, Wardha-442 001 Maharashtra) : The final fate of spherical inhomogeneous dust collapse in higher dimensional spacetime. Indian J Phys-Pt B 2003, 77(3), 345-50.

Searches for the occurrence of naked singularities in higher dimensional Tolman type spherically symmetric spacetime and, if they exist, to invetigate whether the dimensionality of spacetime has any role in the nature of singularities. Shows that dimensionality of spacetime does not essentially change the basic nature of singularity of an inhomogenous dust collapse. Examines the nature of the central singularity forming in the spherically symmertric collapse of dust cloud and it is shown that this is always a strong curvature singularity where gravitational tidal force diverge powerfully.

14 ref

023043   Nayak P K;Vijayan V;Chakravorthy V;Bhatta D; Singh P (Chemistry Dep, Utkal University, Bhubaneswar-751 004) : Estimation of K, U and Th in precambrian ores by low-level γ-ray spectroscopy. Indian J Phys-Pt B 2003, 77(5), 503-6.

Gamma-ray spectroscopy technique has been employed to estimate the concentration of three large ion lithophile elements, namely K, U and Th present in banded iron-formations, ferromanganese oxides the chromites collected from different mines of eastern Indian geological belt. The results obtained by this method have been discussed on the basis of ancient ocean condition, effect of weathering and on selectivity of large io lithophile elements towards major elemental phase, i.e. silica, iron, chromium and manganese.

1 illus, 2 tables, 18 ref

023042   Narayan Bhat M;Dharmaprakash S M (Physics Dep, Mangalore Univ, Mangalagangothri-574 199) : New semiorganic material for optical second harmonic generation : glycine sodium nitrate. J Optics 2002, 31(4), 159-67.

Single crystals of glycine sodium nitrate (GSN) is a semiorganic nonlinear optical material that has been grown from solution by slow evaporation at ambient temperature. the solubility of GSN has been determined in water. Formation of the new crystal has been confirmed by powder X-ray diffraction pattern and IR spectra. The transmission spectra of GSN have been recorded. The optical second harmonic generation (SHG) conversion efficiency was determined using Kurtz-powder technique and found to be two times that of KDP.

5 illus, 2 tables, 15 ref

023041   Miranda P L;Lopez Bonilla J L;Acevedo M; Meneses R (Postgraduate Section of the Superior School of Mechanical and Electric, Politechnic Institute of Mexico Zacatenco Campus, U.P.A.L.M., Edif. Z, Acc, 3, 3er Piso, Col. lindavista, C.P. 07738 Mexico) : Multipath environment indoor analysis by sommerfeld integrals, geometric optics and norton surface-wave. Indian J Phys-Pt B 2003, 77(3), 283-9.

In the analysis of indoor wireless communication systems, the multipath environment is a concerning topic and optimum models are looked for. A frequency and time- domain investigation for an indoor environment by Sommerfeld Integrals, Geometric Optics and Norton Surface Wave in relation to an elementary dipole radiation above a ground plane (plane of reference) has been presented in US Department of Commerce, NTIA Reprot 00-379 (200). These models were applied using a two-elements antenna and the probabilistic model [IEEE Trans. Antennas Prapaget. 48 1161 (2000)] of a multipath indoor analysis is presented. The results show Sommerfeld integrals have more accuracy of 6 DB than Geometric Optics plus Norton Surface-Wave and of 11 dB than Geometric Optics.

5 illus, 17 ref

023040   Manik N B;Basu A N (Condensed Matter Physics Research Centre, Dept. of Physics, Jadavpur University, Calcutta-700 032) : Calibration and display technique of a nonlinear signal and a computer based low temperature measurement system using thermocouple sensor. Indian J Cryogenics 1997, 22(4), 137-42.

A measurement scheme of low temperature by a computer (PC-XT/AT) using a thermocouple (TC) sensor has been described. Attention has been paid on the process of non-linear signal for calibration and display. It is well known that the variation of thermo-emf with temperature is nonlinear. The process of calibration of nonlinear signal and its display by analog means is rather difficult and it is understood that all the existing sensors have either static or dynamic nonlinear response with respect to input variables. Instead of linearising this nonlinear signal a polynomial fit to the temperature versus thermo-emf as obtained from the experiment is used. The temperature value corresponding to a thermo-emf as obtained from this relation. The cold junction compensation has been done by using another temperature sensor. A commonly available silicon diode In-4148 is used for this purpose. The addition of this compensation voltage has been done by the software technique. The temperature can be measured with an accuracy of the order of ±0.07°C over the temperature range from -196° C to + 100° C. For interfacing the TC sensor to the computer a analog to digital (AD) card ALS-PCO2 has been used.

7 illus, 10 ref

023039   Mahesh Chandra;Bhalla G L;Trigunayat G C (Dept. of Physics and Astrophysics, University of Delhi, Delhi - 7) : Thermal expansion of high temperature super conductors : a survey. Indian J Cryogenics 1997, 22(2), 69-78.

A comparative study of thermal expansion of high temperature superconductors (HTSC) is presented for doped and undoped LaCuO, YBaCuO and BiSrCaCuO superconductors. Distinct features of thermal expansin such as anisotropy, jump at superconducting transition temperature etc. are discussed.

10 illus, 3 tables, 48 ref

023038   Kurian A;George N A;George S D;Unnikrishnan K P;Paul B;Gopinath P;Nampoori;Vallabhan C P G (International School of Photonics, Cochin Univ of Sci & Technology, Cochin-682 022) : Effect of pH on quantum yield of fluorescein using dual beam thermal lens technique. J Optics 2002, 31(1), 29-35.

Dual beam thermal lens technique is employed for the determination of absolute fluorescence quantum yield of fluorescein dye solutions in different pH environments. Dependence of the quantum yield on pH and concentration of dye solution is discussed.

4 illus, 27 ref

023037   Kumar Rai V;Rai S B (Laser and Spectroscopy Laboratory, Department of Physics, Banaras Hindu University, Varanasi-221 005) : Overtone absorption spectra of some aliphatic amines. Indian J Phys-Pt B 2003, 77(3), 351-4.

The infrared and near-infrared overtone absorption spectra of ethyl, n-butyl and isopropyl amines have been studied in pure and diluted form. Vibrational frequency and the anharmonicity constants for the C-H, and symmetric and asymmetric N-H stretching vibrations for the three molecules have been determined using local mode model. A dilution study clearly indicates the presence of intermolecular hydrogen bonding in all the three cases.

3 illus, 5 tables, 5 ref

023036   Khare P K;Verma A;Sahu D K;Srivastava R K (Dept. of P G Studies & Research in Physics, Rani Durgavati University, Jabalpur-482 001 Madhya Pradesh) : The evaluation of dielectric properties of pure polyvinyl pyrrolidone films. Indian J Phys-Pt B 2003, 77(5), 453-7.

Dielectric relaxation are studied by measuring simultaneously the capacitances (permittitivities) and the losses at regularly varying temperatures from 40 to 220° C and at different constant frequencies from 0.5 to 30 kHz, for different electrode configurations of pure polyvinyl pyrrolidone (PVP) films of 20μm tickness. The capacitances are found to increase with the increase in temperature for similar electrode Al-PVP-Al systems, however, in case of dissimilar electrode Al-PVP-Ag combinations, a shoulder peak is found at ~105±5°C and remaining variations are the same, as found in case of similar electrode system. The variation of premittivity with temperature is attributed to thermal expansion in the lower temperature region and to the orientation of dipolar molecules in the neighbourhood of glass rubber transition temperature Tg(~170°C) of PVP. The variation of loss factor with temperature at different constant frequencies show two loss maxima, first at 90±10° C and second at 108±10° C, below and near Tg of PVP, corresponding to α-and β-relaxations of the polymer which shift to lower temperatures as frequency is decreased. The increase in losses with the decrease of frequency is ascribed to the increased in conductivity of the polymer.

4 illus, 21 ref

023035   Khan M;Bhattacharyya A (NO, Centre for Plasma Studies, Jadavpur Univeristy, Kolkata-700 032) : Design, fabrication and characterization of a capacitatively coupled RF discharge plasma system. Indian J Phys-Pt B 2003, 77(3), 323-6.

A capacitatively coupled radio-frequency discharged plasma in a discharge tube of cylindrical topology with low-cost components is fabricated. Argon plasma is produced at 10^-5 mBar pressure and electron density is estimated. Also estimates conductivity of plasma. Thereafter, proposes an analytical model of experimental set-up and compare the results.

3 illus, 9 ref

023034   Kalita P K;Sarma B K;Das H L (Physics Dep, Gauhati University, Guwahati-781 014) : Structural characterization of ZnTe films by x-ray diffraction techniques. Indian J Phys-Pt B 2003, 77(5), 487-90.

Structural defects originating from the lattice misfit in ZnTe thin films can be minimized by depositing the films at elevated substrate temperatures (T_s) in the range 473K-623K and thereby enhancing the film crystallinity. The average stress and microstrain decrease in this T_s range. The conductivity is found to be maximum for film deposited at 473 K. These structural effects in correlation with film conductivity is expected to be governed by the predominant recrystallization process which facilates in reducing native defects in ZnTe films.

2 illus, 1 table, 11 ref

023033   Jana M;Das D (Energy Research Unit, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700 032) : Microcrystallization and /or columnar growth at Si:H network induced by Ar dilution ot the SiH₄ plasma in rf glow discharge. Indian J Phys-Pt B 2003, 77(5), 433-9.

In quest of an alternative to H₂ dilution for rapid microcrystallization, the effect on the Si:H film properties has been studied for Ar dilution to the SiH₄ plasma over an extremely wide range from Φ(Ar)=Ar/SiH₄=60 to 1200. It is demonstrated that Ar dilution in SiH₄ plasma induces crystallization i Si:H at a low rf power. It is proposed that Ar^* in Ar-diluted plasma plays an analogous role for initiating microcrystallization, as atomic H does in H₂-diluted plasma. However, extremely high Ar dilution induces a heterogenous network and leads to columnar structure.

9 illus, 17 ref

023032   Gupta S;Bhalla G L (Department of Physics and Astrophysics, University of Delhi, Delhi - 110 007) : Synthesis and characterisation at Ag-Doped YBCO. Indian J Cryogenics 1997, 22(2), 53-6.

Electrical resistance, X-ray diffraction and microstructural analysis of Ag-doped YBa₂ (Cu_1-xAg_?x)₃ O_7-y superconductors with x=0, 0.04, 0.08, 0.12, 0.16, 0.18. In the low doping limit. Ag impurities behave as an oxygen stabilizing agent and results in enhancement of critical temperature. Increase in "c" cell parameter with x is found. Microstructural investigations exhibit betterdensification with Ag-substitution owing to the formation of liquid phase at high doping levels.

3 illus, 1 table, 7 ref

023031   Gupta K K;Singh P J (Physics Dep, M. S. J. College, Bharatpur, Rajasthan-321 001) : Influence of solvent environment on dielectric behaviour of cyclohexylamine. Indian J Phys-Pt B 2003, 77(3), 299-302.

Dielectric study of cyclohexylamine has been carried out with three non-polar solvent such as benzene, n-heptane and 1, 4-dioxane at 313 K. Molar polarization (P₂), Kirkwood correlation factor (g), excess correlation factor (δg) and excess free energy (ΔG) have been determined for the molecule as a function of mole fraction of solute using static dielectric constant and dieliectric constant at optical frequency. The g values are greatly affected by the presence of different environment. In 1, 4-dioxane, the high values of g as compared to other two environmentas is explained on the basis of hydrogen bonding interaction. Presence of α and β multimers is identified for all the environments.

3 illus, 1 table, 10 ref

023030   Gunasekaran S;Hemamalini R (Physics Dep, Queen Mary's College, Chennai-600 004) : Spectroscopic analysis on the structure of poly methylmethacrylate (PMMA). Indian J Phys-Pt B 2003, 77(3), 319-22.

Studies of the structure and potential energy distribution of crystalline Poly Methylmethacrylate (PMMA). A quanlitative analysis of the pure sample of PMMA has been made by a satisfactory vibration band assignment using FTIR and Raman spectra. A normal coordinate analysis has been carried out using the method of kinetic constants. A systematic set of potential constants have been computed using the method of kinetic constants on the basis of C_s

3 illus, 1 tables, 19 ref

023029   Garg A;Singh A P;Kapoor A;Tripathi K N (Electronic Sci Dep, Univ of Delhi, South Campus, Bentio Juarez Road, New Delhi-110 021) : Multiple pulse laser induced damage studies in InSb at1.06μm wavelength-a comparative study in nanosecond and picosecond regime. J Optics 2002, 31(1), 9-15.

Experimental investigations of multiple pulse laser damage at 1.06μm wavelength in InSb crystal with nanosecond and picosecond pulses near single pulse damage threshold is reported. Damage morphology in two cases is widely different. Damage morphology in nanosecond regime is consistent with surface melting and solidification alongwith an evidence of subsurface overheating. Multiple pulse damage in picosecond regime clearly shows strong influence of subsurface over heating in the sample. Thermal modeling of pulsed laser heating of InSb at 1.06μm wavelength clearly shows nonequilibrium heating of smaple surface.

4 illus, 1 table, 14 ref

023028   Dubey J D;Singh R K;Mahto T P (University Dept. of Physics, Vinoba Bhave University, Hazaribag-825 301) : Energy band gap of β-GaN and its variation with pressure. Indian J Phys-Pt B 2003, 77(5), 491-3.

A semi-empirical calculation has been carried out to find out the energy band gap of Gallium Nitride in Zinc Blende sturucture. The normal or zero pressure lattice constant has then been used as variables parameter, and the band gap and the deformation potential has been calculated for ten values of the parameters below and above the normal lattice constant. The lattice parameter variation corresponds to pressure variation of about ± Kbar. The bad gap is not found to vary linearly, the E_g→a curve showing concavity upwards, thereby eliminating the possibility of a transition to metallic phase. The results are compared with available data from other reported works.

2 illus, 8 ref

023027   Dorendrajit Singh S;Shambhunath Singh W; Mazumdar P S (Physics Dep, Manipur University, Canchipur-795 003 Manipur) : Thermoluminescence of NaCl and NaCl:Rb. Indian J Phys-Pt B 2003, 77(5), 499-502.

Comparison of optical absorption spectrum and TL of pure NaCl and NaCl:Rb 90.7% by weight) is made. The composite TL peaks of pure and doped NaCl are deconvoluted using both general order (GO) and mixed order (MO) kinetics model giving the trap parameters. The effect of optical bleaching of γ-irridiated NaCl is discussed. The growth curve of pure NaCl is presented.

4 illus, 1 table, 13 ref

023026   Dey T K;Singh S C;Sinha S K (Department of Physics, Govt. Mahila Inter College, Purnia-854 301 Bihar) : Quantum corrections to equation of state of fluid mixtures of hard non-spherical molecules. Indian J Phys-Pt B 2003, 77(3), 291-7.

The expression for the leading quantum correction to the third virial coefficient and equation of state of the fluid mixture of the hard Gaussian overlap molecules are given. The numerical results are discussed under the conditiosn of (i) σ⁰₂₂=σ⁰_{22 and (ii) v=v2. The quantum effects depend of the conditions and relative values of the shape parameters K in general and increase with the packing fractions η in particular.}

2 illus, 5 tables, 8 ref

023025   Daga O P;Aji Baby;Kothari H S;Singh J K;Singh B R (Opto-Electronics Devices Group, Central Electronics Engineering Res Institute, Pilani (Rajasthan)-333 031) : High power 980-nm in GaAs'AlGaAs strained quantum well lasers for pumping applications. J Optics 2002, 31(4), 153-7.

Deals with the material and device design, technology and recent results on the performance of 980 nm laser diodes developed at CEERI. The issues related to material structure, device design and optimised process parameters are discussed. Typical L-I characteristics of these devices and important device parameters such as threshold current, emission wavelength and slope efficiency are included and discussed.

3 illus, 1 table, 6 ref

023024   Dabhi R M;Joshi M J (Physics Dep, Saurashtra University, Rajkot 360 005 Gujarat) : Thermal studies of gel-grown cadmium tartrate crystals. Indian J Phys-Pt B 2003, 77(5), 481-5.

Cadmium tartrate crystals were grown by the gel method. The effect of optically sensitive tartaric acid. i.e. dextro tartaric acid and levo tartaric acid, was studied. The crystals were having dendritic type morphology. The thermal study was carried out by employing thermogravimetry. The kinetic and thermodynamic parameters were calculated from the thermogram for the dehydration process using Coats and Redferm and Horowitz and Metzger relations.

8 illus,2 tables, 19 ref