022979   Nagarajan P;Sulochana N;Muralidharan V S (P G & Res Chem Dep, Bishop Heber College, Tiruchirapalli-620 017) : Cyclic voltammetric reduction of 7-hydroxy and acetoxy flavones at glassy carbon electrode. Bull Electrochem 2004, 20(2), 93-6.

Electrochemical reduction behavior of 7-acetoxyflavone was compared with 7-hydroxyflavone on glassy carbon electrode with DMF and 60% DMF/Britton Robinson buffer at pH 3.8 & 10.1 using cyclic voltammetry. Single irreversible reduction waves were observed due to the reduction of keto moiety. The effects of change in medium, pH and sweep rate were evaluated. The electrode process was found to be diffusion controlled and enhanced substituent effect was noticed due to extended conjugation. Kinetic parameters were calculated from cyclic voltammetric measurements using R.S. Nichlolson and I. Shain's equation.

3 illus, 3 tables, 7 ref

022978   Kaler R S;Sharma A K;Kamal T S (Electronics and Communication Engng Dep, Thapar Institute of Engng and Technology, Patiala-147 004) : Simulation results for four wave mixing in an optical fibre near zero-dispersion wavelength. J Instn Engrs-Pt ET 2004, 85(Jul), 31-6.

Four wave mixing (FWM) effect has been illustrated through computer simulations. It has been shown that FWM effect can be suppressed by increasing dispersion in the fibre. The FWM signal power decreases with increasing dispersion but the decrease is not same for equal and unequal spacing. The decrease in FWM power is more for unequal spaced channels as compared to equal spaced channels. Further it has been shown that with increase in effective area of the fibre, the FWM effect can be reduced. The combined effects of effective area and dispersion are also investigated for FWM. It has been shown that increasing the effective area and decreasing the dispersion neutralizes the net FWM effect. If both dispersion and effective area is increased, the results for FWM suppression are better. But since, such a fibre is difficult to build, it is suggested that the FWM effect can be suppressed with increased effective area and flatter dispersion slope.

7 illus, 1 table, 7 ref

022113   Yadava S S (Dep of Chemistry, D.D.U. Gorakhpur Univ, Gorakhpur- 273 009) : Evaluation of sound velocity in binary liquid mixtures. J pure appl Ultrasonics 2003, 25(4), 124-9.

Ultrasound velocities of binary liquid mixtures of some huydrocarbons, n-hexane, n-heptane and cyclothexane with isobutanol at 308.15 K and cyclothexane and carbon tetrachloride with n-heptanol at 306.15 K are evaluated using equations proposed by Nomoto, Van Dael and Vangeel, Jacobson relation based on intermolecular free length and Schaafs' equation based on collision factor theory. Sound velocities evaluated by above equations are compared with the experimental values: It is found that the ultrasound velocity evaluated on the basis of Schaafs' collision factor theory gives good agreement with the experimental values for the system studied. Non-ideality in the liquid mixtures has been discussed in terms of U²_exp/U²_imix where U_exp and U_imix are the experimental and ideal mixture velocities respectively.

2 illus, 2 table, 22 ref

022112   Veerarethinamurugan S;Kaliaperumal R (Department of Physics, A V V M Sri Pushpam College (Autonomous), Poondi 613 503) : Dielectric and conductivity studies of pure and doped polyvinyl alcohol at microwave frequencies. Bull Electrochem 2003, 19(8), 377-9.

Dielectric constant and conductivity of pur and iodine doped polyvinyl alcohol at X-band (8-12 GHz) and Ku-band (12-18 GHz) frequencies have been measured at different temperatures in the ang 303-373 K. The results show that in the X-band frequency of 9.01 GHz, the dielectric constant stays close to 2.3 at all temperatures in the range 303-373 K for the undoped sample. Also, the same value is maintained for different doping levels. But the conductivity shows a maginal increase from 4.16 x 10^-3 s/cm to 4.66 x 10^-3 s/cm on iodine doping, In the Ku-band frequency of 15.41 GHz, effective of temperature on the dielectric constant is not appreciable and the conductivity also stays at 4.7 x 10^-3 s/cm upto 353 K, whereas for the doped sample at room temperature for a doping of 0.82% by weight of iodine, the dielectric constant and the conductivity values get almost doubled.

2 illus, 2 tables, 7 ref

022111   Varghese S;Iype M;Mathew E J;Menon C S (School of Pure and Applied Physics, M.G. Univ, Kottayam-686560) : Determination of energy band gap and absorption coefficient of thin films of zinc sulphide, copper phthalocyanin and multilayer ZnS-CuPc from its optical studies. Oriental J Chem 2002, 18(2), 247-52.

Zinc sulphide thin films are deposited onto glass substrates by chemical bath deposition technique (CBD). Thin films of Copper Pathalocyanine (CuPc) are sublimed onto glass substrates in high vacuum at room temperature by thermal evaporation technique. Multi layer ZnS-CuPc thin films are obtained from ZnS films grown on glass substraes by CBD techniques and subsequently vacuum subliming CuPc onto ZnS films. These films are annealed at different temperatures. Optical properties of ZnS, CuPc and multi layer ZnS-CuPc thin films are studied in a UV-VIS-Spectro photometer and the absorbance recorded as a function of photon energy. The optical energy band gap and maximum absorption coefficient of the deposited and annealed sampled sampled are determined.

6 illus, 3 tables, 39 ref

022110   Sastry J V;Smatha K;Sharam A V (Ultrasonic Resarch Laboratories, Dep of Physics, Visakhapatnam 530 003) : Evaluation of excess thermodynamic properties in some binary mixtures. J pure appl Ultrasonics 2003, 25(4), 109-23.

Ultrasonic velocity density, viscosity, in binary mixtures of m-cresol + quinoline at 18°C, 24°C, and 32°C, m-cresol + phenylhydrazine and o-chlorophenol + phenylthydrazine at 32°C, 38°C and 45°C are measured over the entire range of composition. From the experimental data other related thermodynamic parameter viz. adiabatic compressibility, intermolecular free length, excess volume, excess adicabatic compressibility, excess viscosity, Rao's constant and Wada's constant are calculated. The deviation from ideality of these parameters is explained on the basis of molecular interaction between the consittuent of the mixtures.

5 illus, 3 tables, 40 ref

022109   Prakash S;Natarajan S;Algar M (Dep of Physics, Virudhunagar Hindu Nadars Senthikumara Nadar College, Virudhunagar-626001) : Infrared spectra of L-phenylalaninium maleate and L-alaninium maleate. Asian J Spectrosc 2003, 7(3-4), 143-9.

The infrared absorption spectrum of L-phenylalaninium maleate and L-alaninium maleate were recorded at room temperature. Tentative assignments of the observed wavenumbers were made by comparison with the known assignments of wavenumbers of the parents of the complexes. The intermolecular hydrogen bonding in the crystal leads to a shift of bands due to the stretching and bending modes of various functional groups. Also the existence of the ionized carboxylic group in the anion and the anion in cis form were confirmed.

4 illus, 3 tables, 7 ref

022108   Mathew A;Madhusoodanan K N (Dep of Instrumentation, Cochin Univ of Science & Technology, Cochin-682 022) : Optical characterisation of semiconducting amorphous As_xSe_100-x thin films. Asian J Spectrosc 2003, 7(1), 27-33.

Amorphous semiconducting chalcogenide glasses constitute an important class of materials with a wide range of potential applicatoins in device technology. Determination of optical constants of amorphos As_xSe_100-x thin films (10≤x≤60). As_xSe_100-x glasses in bulk form are prepared by the melt quenching technique have been reported. The thin film samples of these glasses are preapred by the technique of thermal evaporation in high vacuum (2x10^-5 Torr) onto glass substrates. The absorption and transmission spectra of these samples are analysed. From the absorption spectra, the optical band gaps are determined. The variation of optical band gap of these samples with composition is investigated and the observed behaviour is explained on the basis of various models proposed by several workers. A simple calculation following traditional methods has been employed for deducing the refractive indices of the samples from the fringe pattern of the transmission spectra and the variation of refractive index with wavelength for different compositions is also investigated.

4 illus, 30 ref

022107   Louati B;Guidara K;Gargouri M;Daoud A (Laboratoire de l'etal solide, Faculte des sciences de Sfax, BP 802, 3018 Sfax, Tunisia) : The possible origin of high-temperature transition in acid phosphate CaHPO₄ and SrHPO₄. Asian J Spectrosc 2003, 7(1), 35-42.

X-ray diffraction DSC and Raman spectroscopy study of AHPO₄ (A= Ca, Sr) are presented. DSC analysis show three endothermic peaks for CaHPO₄ and four peaks for SrHPO₄ in the temperature range 300-700K. The Raman spectra (300-1200cm^-1) were studied from 290 to 413K. The transition at 385K is characterised by the conversion of infinite (HPO₄^2-)₂ into (P₂O<₇^4-) dimers. The activation energy were determined from the plot Δv_1/2 as a function of temperature for the v(P-OH) bands.

10 illus, 5 tables, 11 ref

022106   Koshy J;Jose R;John A M;Thomas J K;Suresh Kumar S;Damodaran A D (Regional Res Lab (CSIR), , Trivandrum-695 019) : High temperature superconductivity: challenges in IPR regime and strategies for national initiatives. J Intellect Prop Right 2004, 7(4), 295-307.

Superconductivity offers unique opportunities for a developing country like India to be a global leader because of the availability of trained manpower resources and the scientific infrastructure. Describes briefly the developments made in the area of high temperture superconductivity (HTS) for the last 15 years and the challenges in IPR regimes. The strategies adopted by countries like US, Japan and Germany in the development and commercialization of HTS are described. Comparison of time line to commercialization of HTS with other technologies like semiconductor, digital network and fibre optics is presented. Importance of national initiatives at governmental and industrial levels, and strategical alliances involving industry, research organizations and academics for superconductor technology development is highlighted.

1 table, 40 ref

022105   Kawski A;Bojarski P (Univ of Gdansk, Institue of Experimental Physics, Wita Stwosza 57, PL-80-952 Gdansk, Poland) : The inertial effect on the rotational fluorescensce depolrization in liquids. Asian J Spectrosc 2003, 7(3-4), 97-123.

Information about the current state of experimental and theoretical works to the problem of rotational fluorescence depolarization of solute molecules in liquids has been given. The following questions are discussed.1: rotational fluorescence depolarization of spherical and asymmetric molecules, 2. influence of the moment of inertia on the rotational fluorescence depolrization, 3. relaxation process in luminescent solutions and the viscosity of liquids, 4. influence of torsional vibrations on the emission anisotropy in rigid and liquid solutions, 5. comments to the validity of Brownian rotations in solvants at extremely low viscosities.

12 illus, 6 tables, 98 ref

022104   Johnson I;Kalidoss M;Srinivasmoorthy R (Dep of Physcis, St. Joseph's College, Tiruchirappali 620 002) : Evaluation of thermo-acoustic parameters of some binary liquid mixture from volume expansivity data. J pure appl Ultrasonics 2003, 25(4), 136-42.

Researches have previously shown that the contribution of internal pressure and the temperature coeffcient of volume to the sound velocity in the condensed phase is significant and that volume expansivity is the controlling factor for satisfactory description of the various parameters which desribe the thermo-acoustic properties of polycrystalline solid, metal, alkali halide salt, polyatomic ionic liquid and organic liquid mixtures. Such a description employs only volume expansivity data. From the volume expansivity data the isothermal, isobaric and isochoric acoustical paramters, Moelwyn-Hughes parameter, fractional free volume, Huggins parameters, Sharma's parameters and repulsive exponent in Mie's potential have been evaluted in the mixtures of Cyclohexanone + Heptane, Cyclohexanone + Hexane, Cyclonexanone + Octane and Cyloctheaxnone + 2, 2, 4-trimethyl pentane at 308.15 K for the entire range of mole fraction.

8 tables, 14 ref

022103   Ghoshal S K;Gill K S;Gupta U;Devendra Mohan (Dep of Applied Physics, Guru Jambheshwar Univ, Hisar, Haryana-125001) : Light emitting silicon quantum dots: A simulation study. Asian J Spectrosc 2003, 7(1), 1-9.

A computer simulation study is made to look at the variation of the band gap as a function of sizes and shapes of small silicon (Si) dots using pseudo-potential approach. Empirical pseduo-potential Hamiltonian and a plane wave basis expansion and a basic tetrahedral structure have been used. It is found that the gap decreased for increasing dot size. Furthermore, the band gap increases as much as 0.13eV on passivation the surface of the dot with hydrogen. So both quantum confinement and surface passivation determine the optical and electronic properties of siquantum dots. Visible luiminescence is probably due to rediative recombination of electrons and holes in the quantum confined nanostructures. The effect of passivation of the surface dangling bonds by hydrogen atoms and the role of surface states on the gap energy as well as on the HOMO-LUMO states has also been examined. The entire energy spectrum starting from the very low laying ground state to the very high lying exicted states have been investigated for silicon dots having 5, 8, 17, and 18 atoms. The results for size dependence of the HOMO-LUMO gap and the wave functions for the bonding-anti-bonding states are presented and the importance of the confinement and the role of hydrogen passivation on the confinement are also discussed.

2 illus, 15 ref

022102   Ghoshal S K (Department of Applied Physics, Guru Jambheshwar University, Hisar - 125 001) : Role of hydrogen on the HOMO-LUMO states of light emitting silicon quantum dots: an empirical pseudo-potential calculation. Asian J Spectrosc 2003, 7(2), 49-68.

A computer simulaion study of electronic properties of silicon nanoclusters has been presented to examine the variation of the HOMO-LUMO gap and the wave functions for the bonding-anti-bonding states as a function of sizes and shapes of small silicon (Si) dots using empirical pseudo-potential approach. Small dots having 5, 8, 17 and 18 atoms are investigated for both free as well as hydrogen passivated surfaces with no bond distortion and no overall symmetry. empirical pseudo-potential Hamiltonian with plane wave basis expansion is used for basic tetrahedral structure. The gap decreases for increasing dot size and increase as much as 0.13eV on passivation the surface of the dot with hydrogen indicates that the quantum confinement and surface passivation determine the optical and electronic properties of these structures. The entire energy spectrum starting from the very low lying ground state to the very high lying excited states has been looked into to examine the microscopic properties of individual dots responsible for visible luminescence. With hydrogen passivation, the localised dangling bond states eliminated, resulting a wider energy gap. The role of surface passivated hydrogen on the confinement and the importance of the confinement is also discussed. To support the empirical pseudo-potential data simulation based on non-orthogonal tight-bonding model for local analysis of electronic structure, which are in good agreement was performed. The optical properties of a single dot in the light of electron correlation effects have been dealt with.

8 illus, 1 table, 35 ref

022101   Deshmukh C C;Doshi A G;Deshmukh C M (Vidyabharti Institute of Research, P.G. Studies in Sci and Mangement, Amravati - 444602) : Ultrasonic behaviour of substituted pyrazoline and its complexes. J pure appl Ultrasonics 2003, 25(4), 105-8.

Ultrasonic velocity and density measurements on 3 - (2-hydroxy - 3,5 - dichloro phenyl) -5- (2-furyl) Δ² - Pyrazoline and ints complexes with Fe (II), Ni (II), CO (II), Cu (II), Mn (II), Cr (II) in acetone as a solvent, have been carried out at 298.5 K. Different acoustic properties like apparent maolar volume, apparent molar compressibility, intermolecular free length etc. have been determined. The parameters so obtained have been interpreted in terms of solute-solvent and solute-solute interactions.

2 illus, 1 table 14 ref

022100   Bayrakceken F;Keskin A U (Yeditepe Univ, Dep of Electronics Engineering, 34755, Istanbul, Turkey) : Photochromism and thermochromism of trimethylindolinobenzospiropyran in methanol. Asian J Spectrosc 2003, 7(3-4), 137-41.

Two forms of the title compound have been observed, one being colorless or light yellow, the other highly colored. The colorless form has structure, since the geometry of the spyro carbon requires that the rings be approximately at right angles to each other, effectively isolating the π) electrons of the seperate systems and restriciting light absorption to the ultraviolet region of the spectrum. The thermal formation of colored species was measured by observing the increase in abosorbance at 570 nm with an increase in temperature, 50°)C. The solution was then allowed to stand for one hour permitting a reestablishment of equilibrium and the absorption spectra was then recorded. The spectra in all cases were idential within experimental error. It has been shown that thermochromic and photochromic colours are in fact spectroscopically identical. The thermal transient decay followed first-order kinetics regardless of the wave length selected.

3 illus, 8 ref

022099   Bayrakceken F;Karaaslan I S (Yeditepe Univ, Dep of Electronics Engineering, Istanbul-34755 Turkey) : Anti-stokes Raman scattering of triptycene in solution. Asian J Spectrosc 2003, 7(3-4), 125-8.

The ultraviolet absorption and emissions as well as anti-Stokes Raman scattering of spectroscopically pure triptycene was investigated by flash and laser flash photolysis technique in solution at room temperature and at 77°K. The whole spectrum, absorption, excitation, fluorescence, phosphorescence, T-T absorption, and Anti-Stokes Raman scattering spectra were recorded photographically and photoelecrtrically in the ultraviolet region. Scattered lines were observed at 360 and 380 nm, or phosphorescence spectrum at 77°K.

1 illus, 17 ref

022098   Bayrakceken F (Yeditep Univ, Dep of Electronics Engineering, Istanbul 81120 Turkey) : Triplet triplet absorption spectrum of 1,2,3,4-dibenzanthracene in EPA. Asian J Spectrosc 2003, 7(1), 11-3.

Triplet-triplet absorption spectrum was experimentally observed by flash and laser flash photolysis at room temperature. Dibenzanthracene molecules were excited in a two-step process. In the first step, an excited singlet level by intersytem crossing. The recreated first excited singlet of dibenzathracene decays back to the ground state by emitting B-Type of delayed fluorescence which was observed at the same emission band of prompt fluorescence.

1 illus, 9 ref

022097   Bayrak A B;Bayrakceken F;Keskin A U (Yeditepe Univ, Dep of Electronics Engineering, 34755 Istanbul Turkey) : Spectroscopic study of p-methoxy-styrene in aqueous media. Asian J Spectrosc 2003, 7(1), 15-8.

Flash spectroscopic study of p-methoxy-styrene (hereafter PMS) inwater at room temperature gave first order photochemical reactions. In the first step an exicted singlet S₁ is created then S₁→S₀ transitions were recorded. The 1/e decay time of promt fluoresence of PMS in water at room temperature were measured by using flash photolysis technique, and the fluorescence decay time was found to be 19 ns. Due to the various quenching processes neither delayed fluorescences nor triplet-triplet emissions could be recorded.

4 illus, 1 table, 10 ref

000057   Varma S (Institute of Physics, , Bhubaneswar-751005) : Scanning Probe Microscopes. Phys Educ 2003, 20(1-2), 51-6.

The scanning probe microscopes (SPM) Scanning Tunneling Microscope (STM) and Atomic Force microscope (AFM), have revolutionzed the physics of surface as these techniques allow one to observe the topography of the surfaces with atomic resolution in real space. These techniques have become also useful in the other branches like biology, nanostructures, devices etc.

6 illus, tables, 9 ref

000056   Singh S P;Aman;Tarafder A (Department of Ceramic Engineering, Institute of Technology, Banaras Hindu University, Varanasi 221 005) : Comparative investigation on the effect of alkaline earth oxides on the intesity of absorption bands due to Cu<. Bull Mater Sci 2004, 27(3), 281-7.

Absorption characteristics of Cu²⁺, Mn³⁺ and Cr³⁺ ions in ternary silicate (20Na₂O.10RO.70SiO₂, where R+Ca,Sr,Ba) glasses were investigated. The intensities of absorption bands due to Cu²⁺ ion was found to increase with increasing ionic radii of the alkaline earth ions whereas it was found to decrease in case of Mn³⁺ and Cr³⁺ ions with increasing ionic radii of the alkaline earth ions. The results were discussed in the light of relation between linear extinction coefficients of these ions and coulombic force of alkaline earth ions. The change in intensities of Cu²⁺, Mn³⁺ and Cr³⁺ ion is attributed due to change in silicate glass compositions.

4 illus, 4 tables, 25 ref

000055   Singh N L;Sharma A;Shrinet V;Rakshit A K; Avasthi D K (Department of Physics, Department of Chemistry, M S University of Baroda, Vadodara 390 002) : Electrical properties of ion irradiated polypropylene films. Bull Mater Sci 2004, 27(3), 263-7.

The effect of high-energy (50 MeV) Li³⁺ ion beam irradiation on polypropylene (PP) film has been studies in the fluence range 2.4 x 10¹²-1.5 x 10¹⁴ ions/cm². The a.e. electrical properties of PP films were measured in the frequency range from 0.05-100 kHz, and at temperature range between 30 and 140°C. This study indicates two peaks at 60°C and 120°C with comparatively high magnitudes. There is an exponential increase in conductivity with log of frequency and the effect is significant at higher fluences. The loss factor (tan δ) vs frequency plot suggests that PP film based capacitors may be useful below 10 kHz. The capacitance is constant over a wide temperature range up to 130°C. FTIR spectra of the PP films before and after irradiation indicate that intensity of C-H stretching vibration at 2900 cm^-1 is modified. The presence of many new peaks with the increase of fluence suggests the formation of alkanes and alkynes which might by responsible for the observed changes in the dielectric and electrical properties of PP films.

7 illus, 15 ref

000054   Sarathi R;Chandrasekar S;Sabari Giri V; Venkataseshaiah C;Velmurugan R (Department of Electrical Engineering, Composite Technology Centre, Indian Institute of Technology Madras, Chennai 600 036) : Analysis of surface degradation of high density polyethylene (HDPE) insulation material due o tracking. Bull Mater Sci 2004, 27(3), 251-62.

Tracking phenomena has been studied with HDPE material under a.c. voltage, with ammonium chloride as the contaminant. It is noticed that the tracking time depends on the conductivity and flow rate of the material were identified by carrying out a methodical experimental study. The physico-chemical analyses viz. wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and dynamic mechanical analyses (DMA), were carried out and it was concluded that the mechanism of tracking process is due to the surface degradation. The surface condition of the insulation structure was characterized for any surface discharges or tracking, using the leakage current measurement, utilizing the wavelet concepts.

15 illus, 5 tables, 14 ref

000053   Sanmathi C S;Prasannakumar S;Sherigara B S (Department of Industrial Chemistry, Kuvempu University, Jnana Sahyadri, Shankaraghatta, Shimoga 57 451) : Terpolymerization of 2-ethoxy ethylmethacrylate, styrene and maleic anhydride:determination of the reactivity ratios. Bull Mater Sci 2004, 27(3), 243-9.

Terpolymerization of 2-ethoxyethyl methacrylate(2-EOEMA), styrene (St) and maleic anhydride (Ma) initiated by benzoyl peroxide was carried out in acetone as common solvent for three monomers. The structure and composition of terpolymer were determined by FTIR spectroscopy by recording analytical absorption bands for St (3002 cm^-1), Ma (1781 cm^-1 and 2-EOEMA (1261 cm^-1) units, respectively. The reactivity ratios for the monomers were calculated according to the general copolymerization equations following the Finnemann-Ross and Kelen-Tudos models. The results show that terpolymerization were carried out through primary `complex" mechanism at near-binary copolymerization of {St...Ma} complex with 2-EOEMA. Structure of the resulting terpolymer illustrated by ¹H-NMR and differential scanning calorimeter showed reduction in T_g value.

6 illus, 3 tables, 23 ref

000052   Saha R;Bhattacharyya S P (Phys Chem Dep, Indian Ass for the Cultiv of Sci, Jadavapur, Kolkata-700 032) : On solving schrodinger equation for the ground state of a two-electron atom using genetic algorithm. Curr Sci 2004, 86(7), 960-3.

A recipe is proposed for solving the radial Schrodinger equation (SE) for ground state of helium atom using genetic algorithm. A fitness landscape is generated and the problem of solving the radial SE is reduced to a search for the maximum on this landscape.

2 illus, 10 ref

000051   Pasricha R (Centre for Material Characterization, National Chemical Laboratory, Pune-411008) : Transmission Electron Microscope. Phys Educ 2003, 20(1-2), 41.

Nanophase and naopartilce materials are a new generation of advanced materials that are expected to exhibited unusual chemical and physical properties different from those of bulk materials. The unique properties of nanophase materials are deterimined by their atomic scale structures. This study is only possible with the use of Transmission Electron Microscopes (TEM) as the wavelength of electrons allows for the study at this level. This article deals with the principle of TEM, the process of image formation and the application of this sophisticated instrument.

3 illus, tables, 4 ref

000050   Mythili C V;Retna A M;Gopalakrishnan S (Department of Chemistry, Manonmaniam Sundaranar University, Abishekapatti, Tirunelveli 627 012) : Synthesis, mechanical, thermal and chemical properties of polyurethanes based on cardanol. Bull Mater Sci 2004, 27(3), 235-41.

Cardanol, an excellent monomer for polymer production, has been isolated form CNSL and allowed to react with formaldehyde in a particular mole ratio in the presence of glutaric acid catalyst to give high-ortho novolac resin. Such characterized polyol has been condensed with diphenylmethane diisocyanate to produce rigid polyurethane. A commercially available polyol, polypropylene glycol-2000 (PPG-2000), has also been condensed with diphenylmethane diisocyanate and polyol to produce tough polyurethane. These polyurethanes were characterized with respect to their resistance to chemical reagents and mechanical properties such as tensile strength, percentage elongation, tear strength and hardness. Differential thermal analysis (DTA) and thermo-gravimetric analysis (TGA) were undertaken for thermal characterization.

6 illus, 3 tables, 18 ref

000049   Meeto Singh;Sharma J K;Parashar J (Appl Phys Dep, Samrat Ashok Technol Inst, Vidisha-464 001) : Resonant sum frequency generation in a semiconductor with a magnetic wiggler. Curr Sci 2004, 86(7), 958-60.

Two laser beams propagating collinearly through a semiconductor in the presence of a wiggler magnetic field produce phase-matched sum frequency electromagnetic radiation. The magnetic wiggler provides the uncompensated momentum required to make the process a resonant one. The required wiggler wave number falls with plasma frequency and sum frequency.

^ssc3 illus, 1 table, 14 ref

000048   Malghe Y S;Gurjar A V;Dharwadkar S R (Department of Chemistry, The Institute of Science, 15, Madam Cama Road, Mumbai 400 032) : Synthesis of BaTiO₃ powder from barium titanyl oxalate (BTO) precursor employing microwave heating technique. Bull Mater Sci 2004, 27(3), 217-20.

Cubic barium titanate BaTiO₃ powder was synthesized by heating barium titanyl oxalate hydrate, BaTiO(C₂O₄)₂4H₂O (BTO) precursor in microwave heating system in air at 500°C. Heating BTO in microwave about 600°C yielded tetragonal form of BaTiO₃. Experiments repeated in silicon carbide furnace showed that BaTiO₃ was formed only above 700°C. The product obtained was cubic.

5 illus, 13 ref

000047   Latha Kumar;Subramanyam S V (Department of Physics, Indian Institute of Science, Bangalore 560 012) : Structural and electrial properties of amorphous carbon-sulfur composite films. Bull Mater Sci 2004, 27(3), 289-94.

The synthesis of carbon-sulfur composite (a-C:S) films by vapour phase pyrolysis of maleic anhydride and sulfur has been discussed. Structural changes in the system are analysed by scanning electron microscopy and powder X-ray diffraction have been discused. Microhardness test depicts an increase in the value of hardness with an increase in sulfur concentration. Electrical conductivity of composite samples varies with sulfur concentration. Magnetoresistance (MR) measurements show a drastic increase in the value of MR for the samples prepared at <60>900_°C. Thermal stability of these samples is analysed by thermogravimetric analysis, which depends on the host structure and the amount of intercalated species.

7 illus, 12 ref

000046   Kulkarni S K;Deshpande A C (Dep of Physics, Univ of Pune, Pune-411007) : Scanning near field optical microscope (SNOM). Phys Educ 2003, 20(1-2), 57-63.

An optical miroscope which overcomes the usual /2 limit of the spatial resolution of any optical or electron miroscope and allows very high resoultion in nanometer range using visible wavelength has emerged in recent years as an important microscope. The microscope is known as Scanning Near Field Optical Microscope (SNOM) a Near Field Scanning Optical Microscope (NSOM). It can be used to carry out various spectroscopies like fluorescence, Raman etc. This microscopy is useful for nanometric objects also. This article aims to introduce the exciting field of SNOM to the readers.

7 illus, tables, 4 ref

000045   DhageS R;Gaikwad S P;Samuel V;Ravi V (Physical and Materials Chemistry Division, Catalysis Division, National Chemical Laboratory, Pune 411 008) : Synthesis of nanocrystalline SnO₂ powder at 100°C. Bull Mater Sci 2004, 27(3), 221-2.

A simple gel to crystal conversion route has been followed for the preparation of nanocrystalline SnO₂ at 80-100°C under refluxing conditions. Freshly prepared stannic hydroxide gel is allowed to crystallize under refluxing and stiring conditions for 4-6 h. Formaion of nano crystallites of SnO₂ is confirmed by X-ray diffraction (XRD) study. Transmission electron microscopic (TEM) investigations revealed that the average particle size is 30 nm for these powders.

2 illus, 10 ref

000044   Chand Navin;Jain D (Regional Research Laboratory, , Hoshangabad Road, Habibganj Naka, Bhopal 462 026) : Evaluation of a.c. conductivity behaviour of graphite filled polysulphide modified epoxy composites. Bull Mater Sci 2004, 27(3), 227-33.

Composites of epoxy resin having different amounts of graphite particles have been prepared by solution casting method. Temperature dependence of dielectric constant, tan δ and a.c. conductivity was measured in the frequency range, 1-20 kHz, temperature range, 40-180°C for 0.99, 1.96 and 2.91 wt% graphite filled and unfilled epoxy composites. It was observed that the dielectric constant, tan δ and a.c. conductivity increase with increasing temperature. Near the transition temperature the materials show anomalous behaviour for the observed properties. Peaks of dielectric constant, tan δ and a.c. conductivity were observed to shift towards lower temperature with increasing frequency. Clear relaxation (tan δ) peaks around 169°C were observed in epoxy resin, which shifted to lower temperature side on increasing the frequency. Addition of 2.91 wt% graphite shifted the tan δpeaks towards higher temperature side by creating hindrances to the rotation of polymer dipoles. Addition of 2.91 wt% graphite leads to an increased relaxation time τ of dipoles in polysulphide epoxy from 1.44x10^-5-3.92x10^-5(s) at 90°C by creating the hindrance to the rotation of dipoles.

5 illus, 3 tables, 14 ref

000043   Ashtaputure S;Kharrazi S;Kulkarni S k (Dep of Physics, Univ of Pune, Pune-411007) : Spectromicroscopy using synchrotron radiation. Phys Educ 2003, 20(1-2), 67-73.

Microscopy and spectrocopy are usually complementary techniques. Uisng microscopy, one observed the morphological details of a sample surface where as, by spectroscopy one obtains its chemical information and energy level structure. With the availability of intense x-rays at synchrotron radiation facilities, it has now become possible to perform high spatial resolution microscopy combined with spectroscopy. Such microscopes are termed as spectromicroscopes. Since the spectromicroscopes give simultenious infromation of surface morphology and chemical nature, albit as less resolution microscopy combined wiht spectroscopy. Since the specrtromicroscopes give simultenious information of surface morphology and chemical nature, albit at less resolution of about 50 nm, this technique is finding increasing popularity with scientists working in nano science. In this article a comparison of different microscopes along with principles of X-ray photelectron spectroscopy (XPS) and Auger electron spectrosocpy (AES) will be given. A brief discussion on synchrotron radiation source is followed by principle of x-ray photomession electron microscope and an example.

8 illus, tables, 4 ref

000042   Alem A A;Solaimani E (Department of Inorganic Chemistry, Faculty of Chemistry, University of Tabriz, Iran) : Synthesis and crystal structure determination of Br₂SeIBr Polyhalogen-chalcogen. Bull Mater Sci 2004, 27(3), 223-5.

Polyhalogen-chalcogen Br₂SeIBr was synthesized and the crystal structure was determined by single crystal X-ray diffraction method. This compound was prepared in the temperature range 150-50°C which was brownish-red in colour and crystallized in monoclinic crystal system and space group P2_1/e with four molecules per unit cell. Lattice parameters were: a=6.3711(1), b=6.7522(2), c=16.8850(5) Angstrong, d=r=90°,β=95.96°, v=722.45 Angstrong³.

2 illus, 5 tables, 8 ref

020029   Venkateswaran G (Applied Chemistry Div, Bhabha Atomic Research Centre, Mumbai, ) : Chemical decontamination of BWR nuclear systems. BARC Newsl 2003, 237(Oct), 24-36.

The dilute chemical decontamination (DCD) of Clean-up System of Unit-2 of Tarapur Atomic Power Station was carried out during August 2000 during the 16th refuelling outrage of the unit. This was the result of a decade long laboratory cum loop studies, design and indigenous fabrication of components, phase-1 testing without chemicals all of which together finally led to the execution of the actual chemical decontamination of the system. A two-stage three-cycle AP-CEA process developed for stainless steel surfaces, involving an oxidative pre-treatment of the oxide surface using an alkaline permanganate (AP) solution to remove selectively Chromium from the oxide as the first stage and a second stage wherein oxide dissolution was achieved by using a formulation consisting of Citric acid-EDTA-Ascorbic acid (CEA), was employed. Decontamination factors (DFs) ranging from 1.2 to 10 depending on locaiton were obtained. The three regenerative heat exchangers and the two non-regenerative heat exchangers, which are the main pieces of equipment from the surface area consiseration, have shown DFs from 3-10. A total of 3.68 Curies comprising mainly of ⁵¹Cr radioactivity (97%) along with 3.2 kg of chemical Chromium was removed in the three AP cycles. A total of 8.96 Curues comprising mainly of ⁶⁰Co along with 6 kg f chemical Iron was removed from the three citric acid washes cum CEA cycles. The spent decontamination solution was successfully treated with a set of ion-exchange columns. A Na⁺ form of cation exchange resin (gel type) column was employed for the removal of manganese from the spent pre-treatment solution.

8 illus, 7 ref

020028   Thenappan T;Sankar U (Phys Dep, alagappa Univ, Karaikudi-630 003) : Studies on fluid structure and molecular interactions of amides. Indian J pure appl Phys 2004, 42(6), 435-439.

Fluid structure in amides could be readily studied by dielectric measurements by virtue of the influence of local order and the overall dipole moment. The short-range interactions between permanent dipoles could be described by the Kirkwood-Frohlich correlation factor. In dilute solutions of amides with inert solvents, the interaction between the solute species among themselves may be given by the modified form the the correlation factor (g') by taking care of solvent-solvent interaction. The dielectric constants of the binary mixtures of acrylamide, acetamide, benzamide and pthalimide in 1,4-dioxan were measured at 298, 308 and 318 K. The results were interpreted in the light of the theory. The nature of interaction was identified in all systems.

1 illus, 1 table, 22 ref

020027   Singh A K;Vrushali Deo (Instt of Armament Technol, , Girinagar, Pune-411 025) : Vibrating single crystal piezoelectric disc gyroscope. Indian J pure appl Phys 2004, 42(6), 452-8.

Deals with a single crystal piezoelectric disc gyro sensor. The principle of basic operation and the practical structure of the disc vibrating gyro has been described along with the experimental results for a prototype of the gyro sensor. The results obtained show that the proposed disc resonator operates as a gyro sensor, having sensitivity of about 0.9 mV/ "/s, and behaves almost linear in the range of up to 10"/s.

8 illus, 2 tables, 13 ref

020026   Singh A K;Hussain M M;Singh S P;Date V G (Atomic Fuels Div, Bhabha Atomic Research Centre, Mumbai) : Low temperature superconductor - fabrication and application. BARC Newsl 2003, 237(Oct), 198-202.

3 illus, 4 tables, 7 ref

020025   Sharma N K;Gupta B D (Physics Dep, Indian Institute of Technology Delhi, New Delhi-110016) : U-shaped fiber optic pH sensor : effect of temperature and ionic strength. Asian J Phys 2003, 12(2-3), 225-31.

Febrication of a fiber optic pH sensor based on U-shaped probe and dye doped sol-gel immobilization technology is presented. The influence of ionic strength and temperature of the fluid on the response characteristics of the sensor are studied. It has been found that the response curve is independent of ionic strength upto 1.0 M ionic strength. This occurs, possible, due to the presence of these dyes in the film. Their individual effects are of different sign making the net zero. However, the temperature affects the response curve. The effect of temperature is nonlinear. This suggests that the pH sensor is likely to perform best under well-defined sample conditions ©Anita Publicatoins. All rights reserved.

3 illus, tables, 25 ref

020024   Sen S;Aswal D K;Ajay Singh;Rao T V C;Muthe K P;Vyas J C;Gupta S K;Sahni V C;Gupta L C (Technical Physics & Prototype Engineering Div, Bhabha Atomic Research Centre, Mumbai) : Preparation and characterization of MgB₂ superconductor. BARC Newsl 2003, 237(Oct), 133-49.

Superconducting MgB₂ crystallites having a size up to 3x2x1 mm³ have been grown using a liquid-assisted-sintering process under atmospheric pressure of argon. The magnetization measurements have been carried out on MgB₂ samples to determine upper critical field, critical current density and irreversibility line. The obtained values of critical current density and upper critical field were <126>10⁶ A/cm² (at 1 T and 5 K) and 12 T, respectively. The Andreev reflection studies carried on metallic MgB₂/Ag planar junctions revealed a novel two-energy gap like structure for MgB₂. Surface analysis using X-ray photoelectron spectroscopy revealed that MgB₂ is sensitive to environmental degradation.

28 illus, 2 tables, 28 ref

020023   Sehrawat K;Mehra R M (Electronic Sci Dep, Univ of Delhi South Campus, New Delhi-110 021) : Modification in photoluminescence spectra of porous silicon by changing the surrounding dielectric environment. Indian J pure appl Phys 2004, 42(6), 419-22.

A method to control porous silicon (PS) emission properties by changing the dielectric environment surrounding the S-crystallites has been demonstrated by undertaking a systematic investigation of photoluminescence (PL) spectra from PS recorded in a chosen set of organic solvents. On increasing the dielectric constant of the embedding medium from 2 to 24, a drastic drop (about four orders of magnitude) in PL intensity (I_PL) accompanied with a blue shift of about 230 nm has been observed. The results have been explained quantitatively in terms of geminate recombination of an isolated electron hole pair applying Onsagar's model that predicts variation of Onsager length(l_u) with dielectric constant of the embedding medium. This approach leads to Onsager length of the order of the PS nanostructure size for dielectric constant greater than 24, beyond which no further quenching was observed. The results suggest use of materials with low dielectric constant for encapsulating porous silicon without compromising its PL properties.

2 illus, 2 tables, 15 ref

020022   Sebastin S;Abdul Khadar M (School of Pure and Appl Phys, Mahatma Gandhi Univ, Priyadarshini Hills, P.O.kottayam 686 560) : Ac electrical properties of 60B₂O₃-<40-x) PbO-xMCl₂ 50B₂O₃-(50-x)PbO-xMCl₂ (M=Pb, Cd) glasses. Indian J pure appl Phys 2004, 42(6), 445-451.

The glasses 60B₂O₃-<40-x) PbO-xMCl₂ 50B₂O₃-(50-x)PbO-xMCl₂ (M=Pb, Cd) containing different concentration of PbCl₂ and CdCl₂ were prepared. The ionic transference number of the glass samples was determined using dc polarization technique. The ionic transference number obtained is nearly 1 indicating that the electrical conduction in the glass samples is purely ionic. The dependence of ac conductivity and dielectric constant on temperature and frequency was investigated and the electrical moduli were analyzed. The variation of dielectric constant and ac conductivity with increase in mole percentage PBCL₂ or CdCl₂ has been investigated on the basis of structural changes occurring in the glass samples.

6 illus, 1 table, 37 ref

020021   Saxena S K;Mathew C;Ramu Ram;Manolkar R B; Majali M A;Balakrishnan S A;Pillai M R A;Goswami G L (Radiopharmaceuticals Div, Bhabha Atomic Research Centre, Mumbai) : Laser beam welding facility for sealing of miniature radiation sources. BARC Newsl 2003, 237(Oct), 158-60.

A Nd: YAG laser welding facility was installed in the radioactive laboratory of the Radiopharmaceuticals Division, BARC to obtain high quality welds of the titanium encased radiation sources. Radiation sources based on ¹²⁵I for the treatment of ocular tumors were developed which are encapsulated in ISO specified titanium capsules. The inner core of the tiny sources were prepared and were sealed in titanium capsules of dimensions 0.8mm (φ) x 4.5mm (I) by laser welding. the laser beam parameters such as energy, frequency, pulse duration and welding speed were optimized to obtain leak proof welds. Laser welds were also characterised by optical and scanning electron microscopy for assessing their quality. The welded sources showed a total release <60> 5 nCi of ¹²⁵I, which is less than the permissible levels. Describes the laser welding set up and results of initial development work to obtain radioactive leak proof laser welding of the ¹²⁵I sources in titanium capsules.

4 illus, 1 table, 2 ref

020020   Roy S C;Uppirddt K;Shara G L;Bhatnagar M C (Thin Film Laboratory, Dep of Physics, Hauz Khas, New Delhi-110016) : Humdity sensing characteristics of potassium doped barium strontium titanate (Ba_x Sr_{1-xTiO3) thin films prepared by sol-gel technique.} Asian J Phys 2003, 12(2-3), 293-7.

The effect of Potassium doping on the humidity sensing behaviour of sol-gel derived Barium Strontium Titanate (Ba_(x)Si_(1-x)TiO₃) this films have been studied with varied pH conditions of precursor sol. The precursor sol was deposited onto stainless steel substraes by spin coating technique. Ba-acetate, Sr-acetate and Ti-isopropoxide were taken as the initial precursors. For Potassium doping, 10 atomic percent of Potassium acetate salt was dissolved in the BST sol. Also, the precursor sol with two different pH values 8 and 9 taken to study the effect of varying sol pH on humidity sensing behaviour. An MM (metal-insulator-metal) type-sensing device was made and capacitive response of the films was measured as a function of relative humidity. It has been found that potassium doping greatly improves the linear behaviour of humidity sensing characterstics. Also, films deposited from a sol with higher pH were found to be more sensitive to the change in relative humidity as compared to the films prepared lower pH sol. The acelectrical impedance of the both undoped and doped set of samples, as a function of relative humidity has also been studied.

5 illus, tables, 8 ref

020019   Murthy A R K;Rangacharyulu M (Phys Dep, Nagarjuna Univ, Nagarjuna Nagar, Guntur-522 510) : Molecular polarizabilities of some organic solvents. Indian J pure appl Phys 2004, 42(6), 407-10.

The one-dimensional semi-empirical δ-function potential of chemical binding proposed by Lippincott and Stuttman has been applied to calculate the average molecular polarizability of some important organic solvents. the culculated values are compared with the molecular polarizability values calculated using the Lorentz-Lorentz formula. Reasonable agreement between the theoretical and the experimental values is observed.

1 table, 17 ref

020018   Mitra S;Mukhopadhyay R (Solid State Physics Div, Bhabha Atomic Research Centre, Mumbai) : Molecular motions in condensed matter neutron scattering studies. BARC Newsl 2003, 237(Oct), 116-20.

5 illus, 18 ref

020017   Mahmoud M A (Phys Dep, South Valley Univ, Faculty of Science, Sohg-Egypt) : Excitation and ioniation of laser-pumped potassium vapour. Indian J pure appl Phys 2004, 42(6), 429-34.

The excitation and ionization of low dense K vapur (n_o≡10¹⁴ cm^-3) by resonant cw laser radiation (1 ≡10³ w.cm^-2) have been studied theoretically and the processes responsible for the transfer of energy from the laser - excited atoms into ionization have been presented. It has been established that seed electrons created by collisional ionization processes were heated in superelastic collisions with laser excited atoms, and subsequent elctron - impact excitation and ionization as well as Penning ionization of high lying levels lead to the creating of more electrons.

4 illus, 1 table, 28 ref

020016   Krishnakumar V;Arivazhagan M (Postgraduate Dep of Appl Phys, Nehru Memorial Coll, Puthanampatti-621 007) : Vibrational and normal coordinate analysis of xanthine and hypoxanthine. Indian J pure appl Phys 2004, 42(6), 411-18.

The FTIR and FT-Raman spectra of xanthine and hypoxanthine have been recorded in the region 4000-50 cm^-1 and 100-3500 cm^-1 respectively. The normal coordinate calculations were carried out using Wilson's FG matrix mechanism on the basis of General Valence Force Field for both in-plane and out-or-plane vibrations. all the normal modes of vibrations were assigned and discussed. Potential energy constants obtained in this study were refined using numerical methods.

4 illus, 2 tables, 13 ref

020015   Gupta A S (National Phys Lab, , New Delhi-110 012) : High spectral purity cavity stabilized microwave oscillators. Indian J pure appl Phys 2004, 42(6), 459-64.

Low noise microwave oscillators and novel techniques of reducing the close in noise in these oscillators by using a high Q cavity as a frequency discriminator have been presented. In essence the discriminator converts noise induced frequency fluctuations into corresponding phase variations of a signal reflected from it. An accurate model for the noise floor of the cavity discriminator has been described. The noise cancellation depends on factors such as the cavity Q, microwave power into the cavity, the input coupling coefficient and the level of carrier suppression. Experimental results indicate reasonable good agreement with the model.

5 illus, 11 ref