014250   Ahmed M A;Hanafy T A (Dep of Phys Fac of Sci, Cairo Univ, Giza, Egypt) : Optical absorption and electrical properties of polyvinyl alcohol (PVA-gelatin blend. Indian J Phys 2005, 79(10), 1149-55.

The optical obsorption, real (ε') and imaginary parts (ε") of the dielectric constant, dc conductivity (σ), and I-V characteristics of poly vinyl alcohol (PVA)-gelatin blend were investigated in the temperature range of 290 to 460 K. The identification of the structure and assignments of energy bands were derived in terms of the ligand field theory. The main absorption band at 244 nm, was affected by the gelatin concentration. Two relaxation processes namely α_a and α_c were obtained at the glass-rubber transition temperature T_g. The first one is due to the rotation of free C=O and NH₂ groups inside the amorphous pan of PVA while the second one is due to the rotation of the conjugate of C=O groups and semi-crystalline structure on PVA. The calculated values of the activation energies provide us the information about the presence of ionic conduction. At 303 K the conduction mechanism is Ohmic because there is no injection carriers from the electrode contact, while Richardson-Schottky (RS) effect is predominant in the second region at <62> 333 K.

10 illus, 2 tables, 24 ref

014249   Ahmad S N;Khan M R;Moinuddin (Dep of Electron and Commun Engng F/o Engng & Technol, Jamia Millia Islamia, New Delhi-110 025) : Operational transconductance amplifier based voltage-mode universal filter. Indian J pure appl Phys 2005, 43(9), 714-19.

An operational transconductance amplifier (OTA) based voltage-mode universal filter is presented. The proposed circuit employs four OTAs with two grounded capacitors and realizes lowpass, bandpass and highpass filter functions. The pole-frequency W_p and pole-Q, Q_p are orthogonally adjustable by proper choice of transconductance gains of OTAs and capacitor values. The proposed universal filter can also be used for the realization of notch filter function. In addition a current feedback amplifier (CFA)-based universal filter is also realized by converting the OTA-based circuit using standard tranformation method?1 [Hou C L & Wang W Y, IEE Proc Circuits Devices and Systems, 144, 209-212]. Both the circuits have been studied in detail. The simulation results have also been included.

9 illus, 12 ref

014248   Aggarwal S K;Gupta R;Haldar S;Gupta M;Gupta R S (Motilal Nehru Coll, Univ of Delhi, South Campus, New Delhi-110 021) : Analytical model for high temperature performance of non-self aligned SiC MESFET. Indian J pure appl Phys 2005, 43(9), 697-704.

An analytical model to evaluate the performance of a non-self-aligned SiC MESFET at elevated temperatures is developed. The formulation, devoid of complex mathematics takes into account all the major effects such as effective mobility, gate-bias dependent parasitic resistances and self-back gating effect. The model evaluates Ids~Vds characteristics, transconductance, channel conductance, intrinsic device capacitances and their dependence on temperature has also been discussed.

6 illus, 25 ref

014247   Agarwal S;Bhatnagar D (Microwave Lab Dep of Phys, Univ of Raj, Jaipur-302 004, Email: dbhatnagar_2000@rediffmail.com ) : Dielectric behaviour of powdered samples in pellet form at microwave frequencies. Indian J Phys 2005, 79(10), 1203-6.

The dielectric relaxation behaviour of powdered PVC and its pellets is studied at fixed temperature (35°C) and microwave frequency 9.67 GHz. Dielectric parameters ε', ε" relaxation time rand conductivity σ of both types of samples are determined. By using measured data, work on pellets is reported under two conditions. First, these pellet samples are prepared under constant external pressure by varying weight of powdered sample in steps of 0.5 gm. In the second case, weight of powdered sample is kept constant and pellets are prepared by applying different pressures. Based upon measured results, several conclusions are drawn.

4 illus, 2 tables, 8 ref

013265   Tiwary K P;Singh L S S;Purohit R K;Husain M; Zaidi Z H (Dep STOPWORD Phys, Jamia Millia Islamia, New Delhi-110 025) : Etching of CZT material in CCl₂F₂/Ar discharge by ECR etching technique and their surface characterization. Bull pure appl Sci-Sect D 2004, 23(2), 117-22.

ECR Plasma Etching technique is one of the leading techniques in the fabrication of semiconductor devices that leads to anisotropic profiles and damage free surfaces. The ECR plasma etching of CZT in a CCl₂F₂/Ar discharge with rf biasing were investigated at different temperature and different flow rate ratio. The etch rate increases with the increase in flow rate of reactive gas and temperature The etch depths were measured by Dektek Profilometry and the surface morphology were investigated with Scanning Electron Microscopy. Reports the etch results of CZT material obtained at different process temperature and various gas flow rates of CCl₂F₂, and Ar. An attempt on study the defects of the etched surface by spectroscopic method has also been made here in this paper.

6 illus, 9 ref

013264   Tayal V;Gupta G P;Tripathi A N (Dep STOPWORD Phys, S.D. (Postgraduate) Coll, Muzaffarnagar, Email: tayalvikas11@rediffmail.com) : Calculated energy levels, oscillator strengths and lifetimes in Mg-like argon. Indian J Phys 2005, 79(11), 1243-51.

Calculates the excitation energies for the lowest 86 fine-structure levels as well as oscillator strengths and radiative decay rates for the transitions among (1s²2s²2p⁶)3s²(¹S), 3s3p(^1.3P°), 3s3d (^1.3D), 3s4s(^1.3S), 3s4p (^1.3p °), 3s4d (^1.3D), 3s4f(^1.3F°) 3p²(¹S, ³P, ¹D), 3p3d(^1.3D °, ^1.3D°, ^1.3F°), 3p4s(^1.3P°), 3p4p(^1.3S, ^1.3P, ^1.3D), 3p4d(^1.3p°, ^1.3D°, ^1.3F°), 3p4f(^1.3D, ^1.3F, ^1.3G) and 3d²(¹S, ³P, ¹D, ³F, ¹G) states in Ar VII. These states are represented by extensive configuration-interaction (CI) wave functions obtained with the C1V3 computer code of Hibbert. The relativistic effects in intermediate coupling are incorporated by means of the Breit-Pauli Hamiltonian which consists of the non-relativistic term plus the one-body mass correction, Darwin term, and spin-orbit, spin-other-orbit, and spin-spin operators. In order to keep the calculated energy splittings as close as possible to the experimental values, have made small adjustments have been made to the diagonal elements of the Hamiltonian matrices. The energy splitting of 87 fine-structure levels, the oscillator strengths and transition probabilities for some strong dipole-allowed and intercombination transitions and the lifetimes of some fine-structure levels are presented and compared with available experimental and other theoretical values. The calculated fine-structure energies, including their ordering, show excellent agreement (better than 1.0%) with the available experimental results. In this calculation, new data have been predicted for several levels where no other theoretical and experimental results are available.

4 tables, 52 ref

013263   Syam D (NO, Presidency Coll, Kolkata) : Set of new results and a formal equivalence in thermodynamics. Phys Educ 2004, 21(3-4), 207-5.

General relations between partial derivatives, as arrived at in the theory of differential equations, are exploited to generate some new results in thermodynamics. Points out the formal similarity between the Seebeck effect a well-known thermo-electric phenomenon, and a cyclic process involving first order phase transition.

1 illus, 4 tables

013262   Sunil;Sharma A (Dep STOPWORD Appl Sci, Natn Inst of Technol (Deemed University), Hamirpur, Himachal Pradesh-177 005, Email: sunil@recham.ernet.in) : Effect of dust particles on a layer of rotating ferromagnetic fluid heated and soluted from below saturating a porous medium. Indian J Phys 2005, 79(11), 1285-92.

Deals with the theoretical investigation of the effect of dust panicles on a layer of a rotating ferromagnetic fluid heated and soluted from below saturating a porous medium subjected to a transverse uniform magnetic field. For a flat fluid layer contained between two free boundaries, an exact solution is obtained using a linearized stability theory and normal mode analysis method. The cases of stationary convection and oscillatory modes have been discussed. An attempt is also made to obtain the sufficient conditions for the non-existence of overstability.

5 illus, 33 ref

013261   Srivastava O N;Srivastava A;Dash D;Singh D P; Yadav R M;Mishra P R;Singh J (Dep STOPWORD Phys, Banaras Hindu Univ, Varanasi-221 005, Email: hepons@yahoo.com) : Synthesis, characterizations and applications of some nanomaterials (TiO₂ and SiC nanostructured films, organized CNT structures, ZnO structures and CNT-blood platelet clusters. Pramana J Phys 2005, 65(4), 581-92.

TiO₂ nanostructured films have been synthesized by the hydrolysis of Ti[OCH(CH₃)₂]₄ as the precursor. These films have been utilized for the dissociation of phenol contaminant in water. Free-standing nanostructured film of silicon carbide (SiC) has been synthesized, employing a simple and new route of spray pyrolysis technique utilizing a slurry of Si in hexane. Another study is done on organized carbon nanotube (CNT) structures. These are made in the form of hollow cylinders (50 mm length, 4 mm diameter and 1.5 mm wall thickness). These CNT-based cylinders are made of conventional CNT and bamboo-shaped CNT. The filtrations of heavy hydrocarbons and E. coli bacteria from water have been carried out. In addition to this, ZnO nanostructures have also been studied. Another study concerns CNT-blood platelet clusters.

15 illus, 16 ref

013260   Sreelatha C J;Satyanarayana C;Anuradha P (Dep STOPWORD Phys, Kakatiya Univ, Warangal -506 009) : Specific volume studies of binary mixtures of ceto stearyl alcohol and dimethyl sulfoxide forming lyophae. Bull pure appl Sci-Sect D 2005, 24(1), 51-60.

Investigations on the variation of specific volume with temperature play an important role in rheological properties of condensed phases. The deviations from linearity may either be a step-raise or discontinuity of specific volume. The binary mixtures are ceto-stearyl Alcohol (CSA) and dimethyl sulfoxide (DMSO) are reported to exhibit lyotropic mesophase over a wide range of concentrations. Density measurements of these binary mixtures as function of temperature are experimentally determined using capillary method. The specific volumes of these mixtures are estimated and the linear least square fit of the data is reported in the paper.

10 illus, 10 tables, 20 ref

013259   SOOD A K;GHOSH S;DAS A (Dep STOPWORD Phys, Indian Inst of Sci, Bangalore-560 012, Email: asood@physics.iisc.ernet.in ) : Flow-driven voltage generation in carbon nanotubes. Pramana J Phys 2005, 65(4), 571-9.

Flow of various liquids and gases over single-walled carbon nanotube bundles induces an electrical signal (voltage/current) in the sample along the direction of the flow. The electrical response generated by the flow of liquids is found to be logarithmic in the flow speed over a wide range. In contrast, voltage generated by the flow of gas is quadratically dependent on the gas flow velocity. It was found that the underlying physics for the generation of electrical signals by liquids and gases are different. For the liquid, the Coulombic interaction between the ions in the liquid and the charge carriers in the nanotube plays a key role while electrical signal generation due to gas flow is due to an interplay of Bernoulli's principle and Seebeck effect. Unlike the liquid case which is specific to the nanotubes, the gas flow effect can be seen for a variety of solids ranging from single and multi-walled carbon nanotubes, graphite and doped semiconductors.

5 illus, 16 ref

013258   Smarandache F (NO, Univ of NewMexico, 200-College Road Gallup, NM 87301;USA, Email: smarand@unm.edu) : Matter, antimatter and unmatter. Bull pure appl Sci-Sect D 2004, 23(2), 173-7.

Besides matter and antimatter there must exist unmatter (as a new form of matter) in accordance with the neutrosophy theory that between an entity <60>A<62> and its opposite <60>AntiA<62> there exist intermediate entities <60>NeutA<62>. Unmatter is neither matter nor antimatter, but something in between. An atom of unmatter is formed either by (1): electrons, protons, and antineutrons, or by (2): antielectrons, antiprotons, and neutrons. At CERN it will be possible to test the production of unmatter. The existence of unmatter in the universe has a similar chance to that of the antimatter, and its production also difficult for present technologies.

5 ref

013257   Smarandache F (NO, Univ of New Mexico, 200 College Road,Gallup, NM 87301, USA) : Extension of the big bang theory. Bull pure appl Sci-Sect D 2004, 23(2), 139-40.

Proposes the extension of the Big Bang Theory of the origin of the Universe to the model that there are cycles of beginning and ending.

4 ref

013256   Singh S;Shukla R K;Kumar A (Dep STOPWORD Phys, Harcourt Butler Technol Inst, Kanpur-208 002, Email: dr_ashok_kumar@yahoo.com) : Persistent photoconductivity in a-Se_9oGe_10-xIn_x thin films. Indian J Engng Mater Sci 2005, 12(5), 461-6.

Transient photoconductivity has been studied in amorphous Se₉₀Ge_10-xIn_x thin films prepared by vacuum evaporation. It is observed that the decay of photoconductivity is quite slow in these samples. A persistent photoconductivity, with an extremely slow decay rate is also observed during decay process. The magnitude of persistent photoconductivity increases with increase in illumination time, intensity of light and temperature of the films. The results indicate that some kind of photo induced structural changes occur in these samples, which are of reversible nature and have time constants of a few hours. Studies made on various compositions under identical conditions show that the persistent photoconductivity is minimum at 4 at. % of Indium. This discontinuity at an average coordination number <60>Z<62> = 2.2 is closer to the value suggested by topological models based on constraints theory.

4 illus, 40 ref

013255   Sharma R;Pratima C;Lamba S L;Annapoorni S (Dep STOPWORD Phys STOPWORD Astrophys, Univ of Delhi, Delhi-110 007, Email: annapoorni@physics.du.ac.in) : Interaction effects in magnetic oxide nanoparticle systems. Pramana J Phys 2005, 65(4), 739-43.

Interaction effects in magnetic nanoparticle system were studied through a Monte Carlo simulation. The results of simulations were compared with two different magnetic systems, namely, iron oxide polymer nanocomposites prepared by polymerization over core and nanocrystalline cobalt ferrite thin films prepared by sol-gel process. The size of the particles in the nanocomposites were estimated to be <126>15 nm with very little agglomeration. The low values of the coercivity obtained from the hysteresis measurements performed confirm that the system is superparamagnetic. SEM studies showed the cobalt ferrite films to have a nanocrystalline character, with particle sizes in the nanometer range. Hysteresis measurements performed on the thin films coated on silicon do not give evidence of the superparamagnetic transition up to room temperature and the coercivity is found to increase with decreasing film thickness. Comparison with simulations indicate that the nanocomposites behave like a strongly interacting array where exchange interactions lead to high blocking temperatures, whereas the films are representative of a semi-infinite array of magnetic clusters with weak interactions and thickness-dependent magnetic properties.

3 illus, 9 ref

013254   Sharma J C;Kandpal H C;Zaidi Z H (NO, Natn Phys Lab, Dr. K.S. Krishnan Road, New Delhi-110 012) : Determination of correlation properties of moving diffuser by studying the spectrum of the scattered light emerging from two pinholes. Bull pure appl Sci-Sect D 2004, 23(2), 81-92.

Correlation properties of light scattered by a moving diffuser were determined by studying the spectral characteristics of the light that emerges from two pinholes placed behind the diffuser. The amplitude and the phase of the spectral degree of coherence are determined experimentally from spectral measurements in Young's interference experiment. These properties are used for determining the correlation functions of the heights of diffuser surface and the speed with which the diffuser moves.

4 illus, 16 ref

013253   Sharma A (Dep STOPWORD Chem Engng, Indian Inst of Technol, Kanpur-208 016, Email: ashutos@iitk.ac.in) : Self-organized structures in soft confined thin films. Pramana J Phys 2005, 65(4), 601-14.

Presents a mini-review of our recent work on spontaneous, self-organized creation of mesostructures in soft materials like thin films of polymeric liquids and elastic solids. These very small scale, highly confined systems are inherently unstable and thus self-organize into ordered structures which can be exploited for MEMS, sensors, opto-electronic devices and a host of other nanotechnology applications. In particular, mesomechanics requires incorporation of intermolecular interactions and surface tension forces, which are usually inconsequential in classical macroscale mechanics. Points to some experiments and quasi-continuum simulations of self-organized structures in thin soft films which are germane not only to nanotechnology, but also to a spectrum of classical issues such as adhesion/debonding, wetting, coatings, tribology and membranes.

9 illus, 20 ref

013252   Shankar Narayana M;Laxmana Swamy K;Gopi Krishna N;Chandra Lingam S (Dep STOPWORD Phys, Kakatiya Univ, Warangal-506 009) : X-ray studies of lattice strain and Debye-Waller factors of Al-Mg solid solutions. Bull pure appl Sci-Sect D 2004, 23(2), 133-7.

Lattice strain, the Debye-Waller factor and Debye temperatures of five aluminium-magnesium alloys with solute magnesium at five different compositions 5.7, 8.6, 13.9, 16.4 and 19.1 atomic per cent Mg have beeh determined from X-ray diffraction intensities. The experimental values of Debye temperature have been compared with corresponding values obtained from Kopp-Neumann relation. Values of energy of vacancy formation for the alloys studied have been estimated using a relation connecting it with the X-Ray Debye temperature.

1 table, 16 ref

013251   Semalty P D;Kapil Dev (Dep STOPWORD Phys, H N B Garhwal Univ Campus, Badshahithaul, Tehri-Garhwal-249 199, Email: psemalty@sancharnet.in) : Lattice specific heat and local density of states of Pd_0.95Ni_0.05 dilute alloy at low temperature. Indian J Phys 2005, 79(11), 1279-83.

A theoretical study of the low temperature lattice specific heat of PdNi 5.0 at% dilute alloy has been carried out. Green's function method has been used to calculate the local density of states of substitutional impurity and change in lattice specific heat in this dilute palladium-nickel dilute alloy. The condition of resonance and localized modes has been investigated for possible occurrence of these modes. Localized modes have been obtained above the maximum frequency. However, low frequency resonance modes have not been obtained in this system. The impurity-induced reduction in lattice specific heat is explained on the basis of obtained localized modes. The calculation shows an excellent agreement with the measured lattice specific heat in this alloy.

4 illus, 24 ref

013250   Sankarappa T;Prashant Kumar M;Ahmad A;Jaleeli K A;Uthanna S (Dep STOPWORD Phys, Gulbarga Univ, Gulbarga-585 106) : Acoustic absorption and viscosity in some edible oils. Bull pure appl Sci-Sect D 2005, 24(1), 9-17.

Acoustic absorption and viscosity as a function of temperature are measured in some of the refined and unrefined edible oils (coconut, castor, Sunflower, safflower and groundnut) which are predominantly used in south India. Absorption coefficient was observed to be increasing and viscosity decreasing with temperature and these variations are attributed to increase in intermolecular length with temperature. The results are found to be in agreement with others observations made in different oil systems and fatty acids.

2 illus, 17 tables, 17 ref

013249   Salvi S V;Pimpale S S (Dep STOPWORD Phys, Inst of Sci, 15 Madame Cama Road, Mumbai-400 032, Email: sushama_pimpale@rediffmail.com) : Surface origin of light effect in gases. Indian J Phys 2005, 79(11), 1305-11.

A series of comparative measurements in two ozoniser type discharge tubes one filled with air and the other with hydrogen at P = 4 mm Hg have been made. These ozonisers have the same height but different ratios of surface to volume. Using these tubes, the potential variation (50Hz) of the discharge current (i.e. sealer counts) with and without irradiation is taken for two different values of d.c. bias, x = 5 and y = 50 volts. For various potentials, the ratio of discharge currents at the two biases is then determined in dark (D) and under light (L). The difference between the two ratios, i.e. Δ(i_x/i_y)=(i_x/i_y)_I-(i_{x< D>/iy)D, represents the net effect of light at a given potential. The percentage value of this light- effect turns out to be [Δ(ix/iy)/(ix/iy)D]x 100. The measurements are repeated at different potentials in the range 0.7- 3.36kV (r.m.s.) in their increasing and decreasing fields. The non-identity of the current ratios and of the associated effects refers to the hysteresis or anti-hysteresis. In the case of hydrogen, the values of current with decrease in applied potential are found to be greater than those observed during its progressive increase and hence, the process is termed as anti-hysteresis and the hysteresis is observed in the case of air. In air under a c. field, magnitude of the net effect of current ratio is comparatively less pronounced than those observed in hydrogen. For a given potential and temperature, +Δ(ix/iy) inverts to -Δ(ix/iy), as the potential is increased progressively above the threshold potential. The origin of this light effect is traced to the action of light on electronic surface charges (produced under discharge) on the glass walls of an annular discharge space of the ozoniser tube. Mechanism of the discharge as also that of the formation of surface charge is explained.}

4 illus, 5 tables, 33 ref

013248   Sailaja R;Sreeja V;Bisht P B (Dep STOPWORD Phys, Indian Inst of Technol, Madras, Chennai-600 036, Email: bisht@iitm.ac.in) : Studies of self-phase modulation under cw and picosecond laser pumping: white light continuum generation in water. Indian J Phys 2005, 79(11), 1299-1304.

White light continuum generation (WLC) has been studied in water, D₂O and their mixture under ps laser pumping. Its spectrum extends from 450 to 970 nm. Strong contributions from self-phase modulation (SPM) and stimulated Raman scattering (SRS) are observed. To study the spatial SPM and SRS separately from each other, the stimulated Raman scattering spectrum has been recorded for acetone by using the ps laser at 1064 nm while the effect of spatial SPM is demonstrated with a Gaussian profile of Ar ion laser in an organic dye. The high optical nonlinearity of the dye results in diffracted rings in the far field of the observed diffracted pattern. A comparison with the WLC obtained by fs pumping, has been given on the basis of the available data in the literature.

6 illus, 30 ref

013247   Sahoo S;Mandal M K (Dep STOPWORD Phys, Natn Inst of Technol, Durgapur-713 209, Email: sukadevsahoo@yahoo.com) : How simple is simple harmonic motion?. Phys Educ 2004, 21(3-4), 207-12.

Simple harmonic motion is one of the commonest types of motion found in nature. Examples are ranging from the ripples on a pond to radio waves. The analysis of simple harmonic motion (SHM) is of great significance because it is not only of tremendous practical importance but it also allows us to understand various systems for example, mechanical, acoustical, electrical, atomic etc. Among various varieties of oscillatory motions, SHM is of central importance for three reasons: (i) The oscillation of all physical systems is simple harmonic or a close approximation to it, if the oscillation is not too violent, (ii) We can study complex oscillations with the help of SHM. Complex Oscillations can be expressed as a superposition of harmonic motions. (iii) The study of SHM is essential for the understanding of wave motion. Discusses SHM, its differential equation and solution of the differential equation very briefly.

2 illus, 7 ref

013246   Ramasamy V;Ponnusamy V;Meenakshisundaram V; Gajendran V (Dep STOPWORD Phys, Annamalai Univ, Annamalainagar-608 002, Email: srsaranram@rediffmail.com) : Evaluation of natural radioactivity and radiological hazards in various granites of Tamil Nadu. Indian J Phys 2005, 79(11), 1293-7.

The radioactivity concentrations of ²³⁸U, ²³²Th and ⁴⁰K have been determined by gamma ray spectrometry with Nal(Tl) detector in granitic samples collected from different places of western ghat granitic quarries, Tamilnadu. The samples showed high mean concentrations of 42.02 Bqkg^-1 for ²³⁸U, 236.90 Bqkg^-1 for ²³²Th and 1196.47 Bqkg^-1 for ⁴⁰K. The mean annual effective dose equivalent of 266.11 μSvy^-1 was found. A linear relationship is obtained for ERDM values with calculated dose rates. Assessment of radiological hazards was made by calculating radium equivalent (Ra_eq) activities with external and internal hazard indices. The Ra_eq activity ranges from 304.48 Bqkg^-1 to 741.50 Bqkg^-1 with a mean of 472.93 Bqkg^-1. The external and internal hazard indices range from 0.8222 to 2.0022 and 0.9039 to 2.1804 with a mean of 1.2770 and 1.3906, respectively. A positive correlation is obtained for total activity, calculated absorbed dose rate and Ra_eq with Si-content. The investigations show some granites are having hazardous nature to human health.

2 illus, 2 tables, 13 ref

013245   Rajamoorthy M;Selvarajan P;Srinivasan N; Sivadhass A (P G Dept STOPWORD Phys, Sri Paramakalyani Coll, Alwarkurichi-627 412) : XRD, FTIR, thermal and dielectric studies of barium oxalate crystals grown by gel technique. Bull pure appl Sci-Sect D 2005, 24(1), 33-40.

Single crystals of barium oxalate were grown by diffusion of aqueous solution of barium chloride into the set gel embedded with oxalic acid. The grown crystals were subjected to various studies like powder X-ray diffraction (XRD) studies. Fourier transform Infrared (FTIR) spectroscopic studies, thermal and dielectric studies. Well defined Bragg peaks at specific 2 θ angles in the X-ray diffraction pattern suggested that the grown crystals were single crystalline in nature. The various functional groups of the grown crystals were established from the FTIR spectrum and from thermal studies, it was established that there were only transformations associated with mass changes. From dielectric studies, it was observed that the dielectric constant and loss of the grown crystals increase with increase in temperature. The obtained results were reported and discussed.

6 illus, 2 tables, 14 ref

013244   Rajamannan B;Viruthagiri G;Ravisankar R; Krishnan A;Meenakshisundaram V (Dep STOPWORD Phys, Annamalai Univ, Annamalainagar-608 002, Email: cdmrasikrishll@sify.com) : Natural radioactivity measurement of brick samples of Cuddalore district, Tamil Nadu. Indian J Phys 2005, 79(11), 1319-20.

The specific radioactivity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K were measured using a gamma ray spectroscopy technique. The average values of radium equivalent (Ra_eq) activities in samples collected from two riverbed areas, Cuddalore district. Tamilnadu. India, were calculated. These values are within the limit (i.e.. less than 370 Bq kg^-1) recommended for the safe use of construction materials by OECD Nuclear Energy Agency Paris (1979).

2 tables, 6 ref

013243   Raghu A;Ananthamurthy S (Dep STOPWORD Phys, Bangalore Univ, Bangalore-560 056, Email: sharath_ananthamurthy@hotmail.com) : Construction of an optical tweezer for nanometer scale rheology. Pramana J Phys 2005, 65(4), 699-705.

Optical tweezer is a versatile set-up that can be employed in a wide variety of studies investigating the microscopic properties of materials. In particular, this set-up has in recent times been gainfully employed in probing rheological properties of materials that exhibit viscoelasticity. These measurements can provide data at the micro and nanometer scales, not normally accessible by rheometers that are used for measurements on bulk samples. Describes a single laser beam optical tweezer set-up, which is built around an inverted open microscope. The trapped polystyrene particle bead's deviation from the trap potential minimum is monitored by laser back-scattering technique and the bead position measured by a quadrant photodiode detector. Additionally, a provision is made for video microscopic studies on dispersed beads using a CCD camera. A single particle microrheological experiment that can be performed using the set-up is described with relevant calculations.

2 illus, 21 ref

013242   Rabounski D (NO, , Sirenevi boulevard, 69-1-65, Moscow 105484, Russia) : The speed of gravitation. Bull pure appl Sci-Sect D 2004, 23(2), 141-8.

Regular approach looks the speed of gravitation as a speed of weak waves of the metrics. Study realizes a new approach, defining the speed as a speed of travelling waves in the field of gravitational inertial force. D'Alembert's equations of the field show that this speed is equal to the light velocity corrected with gravitational potential. The approach leads to the new experiment to measure the speed of gravitation, which, having "detectors" like as planets and their satellites a base, is not linked to deviation of geodesic lines and quadrupole mass-detectors with its specific technical problems.

11 ref

013241   Prasad R;Anju;Gupta R N;Gupta G K (Dep STOPWORD Phys, DDU Gorakhpur Univ, Gorakhpur-273 009) : Electrical characterization of multilayer thin films. Bull pure appl Sci-Sect D 2004, 23(2), 71-4.

Multilayer thin films of gallium arsenide germanium of different thicknesses between 14 to 77 nm were deposited on glass substrate at room temperature in high vacuum of 5 x 10^-6 torr by electron beam evaporation technique, in individual evaporation technique in individual evaporations. The conductivity of these films was determined by measuring the developed current with applied voltage at different temperatures between the probe points four-probe system. It is found that the conductivity is linear function of reciprocal temperature; decreasing with decreasing temperature, in the temperature range studied and also decreasing with film thickness. From the slope of the plot, the activation energy evaluated to be about 0.500eV.

2 illus, 17 ref

013240   Pathare S R;Pradhan H C (NO, Homi Bhabha Cent for Sci Educ (TIFR), Mumbai) : Students' alternative conceptions in pressure, heat and temperature. Phys Educ 2004, 21(3-4), 213-15.

Heat and thermodynamics is a major component of physics curricula from the higher secondary school stage. The conceptual and non-intuitive nature of the topic makes it difficult for both learning as well as teaching. As a result students develop many alternative conceptions in this topic. Explores students alternative conceptions with respect to basic concepts in thermodynamics like heat, temperature and pressure. Finds that for students heat and temperature are not different. They do not seem to understand the concept of thermal equilibrium. Further, for them pressure is predominantly the weight of a vertical column of a fluid.

4 illus, 1 table, 6 ref

013239   Panchal C J (Dep STOPWORD Appl Phys Fac STOPWORD Technol STOPWORD Engng, M.S. Univ of Baroda, Vadodara-390 001, Email: cjpanchal_msu@yahoo.com) : Fabrication and characterization of CdSe thin film transistor (TFT) using Y₂O₃ gate insulator. Indian J Phys 2005, 79(11), 1269-73.

A thin film transistor (TFT) using CdSe was fabricated on glass substrates with Y₂O₃ gate insulator. The fabrication process has been explained in detail. The drain and transfer characteristics of CdSe TFT have been studied and the electrical parameters have been determined. The effect of annealing on the drain characteristics was also studied. Source-drain gap and gate insulator thickness were optimized to enhance the performance of the TFT.

4 illus, 1 table, 18 ref

013238   Pal S;Medda C;Pal S (NO, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur-741 252) : Fitting of a growth curve to fish length data on Puntius sophore (Ham.). J Inld Fish Soc India 2005, 37(1), 75-6.

^ssc1 table, 4 ref

013237   Ojha D P (Cent STOPWORD Liq Crystal Res STOPWORD Educ Fac STOPWORD Phys Sci, Nagarjuna Univ, Nagarjuna Nagar-522 510) : Computer simulations of ordering in CPPB based on quantum mechanics and intermolecular forces. Bull pure appl Sci-Sect D 2004, 23(2), 163-72.

Computer simulations of ordering in 4-cyanophenyl 4-n-pentylbenzoate (CPPB) has been carried out based on quantum mechanics and intermolecular forces. The evaluation of atomic charges and dipole moments at each atomic centre has been carried out using the CNDO/2 method. The modified Rayleigh-Schrodinger perturbation theory along with multicentered-multipole expansion method has been employed to evaluate the long-range intermolecular interactions while '6-exp' potential function has been assumed for short-rang interactions. The various possible geometrical arrangements of molecular pair during the different modes of interactions have been considered and the most favourable configuration of pairing has been obtained. A comparative picture of molecular parameters like total energy, binding energy and total dipole moment of CPPB with other nematogen 5-(trans-4-ethylcyclohexyl)-2-{4-cyanophenyl)-pyrimidine (ECCPP) and 4'-methoxy benzylidene-4-acetoxyaniline (MBAA) has been given. The results are discussed in the light of experimental as well as other theoretical observations.

7 illus, 17 ref

013236   Nair C M;Sabna C;Murty K V G K;Ramanan S V (AU-KBC Res Cent, Madras Inst of Technol, Chromepet, Chennai-600 044, Email: raman@au-kbc.org) : Permeability of R6G across Cx43 hemichannels through a novel combination of patch clamp and surface enhanced Raman spectroscopy. Pramana J Phys 2005, 65(4), 653-61.

Measures the permeability of rhodamine-6G across Cx43 hemichannels reconstituted on a pipette tip. Cx43 hemichannels were overexpressed in Sf9 cells, and affinity-purified. The hemichannels were reconstituted in a lipid bilayer on a pipette tip by the tip-dip method. R6G in the pipette permeated across the channels into the bath. The permeability ot R6G was quantified by measuring R6G concentration in the bath after several hours by surface enhanced Raman spectroscopy (SERS) with 100 nm silver colloid particles. The ratio of the permeability of dye to salt, as extracted by this combined electrical-SERS technique, is compatible with similar ratios for other dyes across whole gap junction channels. The results for the permeability ratio were further compared to fluorescence measurements. The novel combination of patch and SERS techniques can be extended to quantifying the transport of biologically significant non-fluorescent molecules, such as cAMP and IP3, across 1 nm sized pores, such as the gap junction channel.

3 illus, 22 ref

013235   Nair A S;et al (Dep STOPWORD Chem STOPWORD Sophisticated Analyt Instrument Facility, Indian Inst of Technology-Madras, Chennai-600 036, Email: pradeep@iitm.ac.in) : Nanoparticles-chemistry, new synthetic approaches, gas phase clustering and novel applications. Pramana J Phys 2005, 65(4), 631-40.

An overview of the synthesis, chemistry and applications of nanosystems carried out in our laboratory is presented. The discussion is divided into four sections, namely chemistry of nanoparticles, development of new synthetic approaches, gas phase clusters and device structures and applications. In chemistry of nanoparticles' describes a novel reaction between nanoparticles of Ag and Au with halocarbons. The reactions lead to the formation of various carbonaceous materials and metal halides. In development of new synthetic approaches' our one-pot methodologies for the synthesis of core-shell nanosystems of Au, Ag and Cu protected with TiO₂ and ZrO₂ as well as various polymers are discussed. Some results on the interaction of nanoparticles with biomolecules are also detailed in this section. The third section covers the formation of gas phase aggregates/clusters of thiol-protected sub-nanoparticles. Laser desorption of H₂MoO₄, H₂WO₄, MoS₂, and WS₂ giving novel clusters is discussed. The fourth section deals with the development of simple devices and technologies using nanomaterials described above.

6 illus, 53 ref

013234   Nageswara Rao A S;Radhakrishna Murthy C (Dep STOPWORD Phys, Kakatiya Univ, Warangal-506 009) : Whole - atom differential incoherent scattering cross sections at 59.5 keV. Bull pure appl Sci-Sect D 2005, 24(1), 65-7.

Incoherent scattering cross sections are determined at 59.5 keV γ-ray energy in the angles 75<144 90<144 and 105° in Cu, Zn, Nb, Mo, Ag, Cd, In and Sn. The measurements were carried out using an Nal (TI) detector coupled to a ND-62 multichannel analyzer. The scattering functions so determined experimentally have been compared with values evaluated on the basis of non-relalivistic SCF-Hartree-Fock wave function. A reasonable agreement is observed between the theory and experiment with in the limit of experimental errors.

1 table, 9 ref

013233   Nag A;Panda B R;Chattopadhyay A (Dep STOPWORD Chem, Indian Inst of Technol Guwahati, Guwahati-781 039, Email: arun@iitg.ernet.in) : Performing chemical reactions in virtual capillary of surface tension-confined microfluidic devices. Pramana J Phys 2005, 65(4), 621-30.

Reports a new method of fabrication of surface tension-confined microfluidic devices on glass. It has been also successfully carried out some well-known chemical reactions in these fluidic channels to demonstrate the usefulness of these wall-less microchannels. The confined flow path of liquid was achieved on the basis of extreme differences in hydrophobic and hydrophilic characters of the surface. The flow paths were fabricated by making parallel lines using permanent marker pen ink or other polymer on glass surfaces. Two mirror image patterned glass plates were then sandwiched one on top of the other, separated by a thin gap-created using a spacer. The aqueous liquid moves between the surfaces by capillary forces, confined to the hydrophilic areas without wetting the hydrophobic lines, achieving liquid confinement without physical side-walls. Shows that the microfluidic devices designed in such a way can be very useful due to their simplicity and low fabrication cost. More importantly, also demonstrated that the minimum requirement of such a working device is a hydrophilic line surrounded by hydrophobic environment, two walls of which are constituted of air and the rest is made of a hydrophobic surface.

6 illus, 20 ref

013232   Murugan R (Dep STOPWORD Phys, Pondicherry Engng Coll, Pondicherry 605 014, Email: moranamurugan@yahoo.com) : Thermo-raman spectroscopy. Phys Educ 2004, 21(3-4), 189-99.

Great advances made recently in instrumentation have resulted the thermal analysis being an extremely active field with applications in numerous directions. The composition changes and phase transformations of a sample as a function of temperature are important for technological application of materials, which can not be observed directly and in situ with the conventional thermal analysis techniques. Raman spectroscopy has been enthusiastically adopted by the materials community and is becoming more popular for industrial process monitoring. Recently, it was extended to thermal analysis of material in dynamic and static thermal processes to monitor the composition changes and phase transformations based on the spectra measured in a temperature interval of 1°C and named as thermo-Raman spectroscopy (TRS). Different forms of thermograms; band position, intensity, intensity variation, and bandwidth as a function of temperature were also plotted to derive detail information about the composition changes and phase transformations.

6 illus, 2 tables, 32 ref

013231   Lakshmi S;Pati S K (Theoretical Sci Unit, Jawaharlal Nehru Cent for Advd Scientific Res, Jakkur P.O., Bangalore-560 064, Email: pati@jncasr.ac.in) : Negative differential resistance in a one-dimensional molecular wire with odd number of atoms. Pramana J Phys 2005, 65(4), 593-9.

Investigates the effects of electron-phonon coupling on the current-voltage characteristics of a one-dimensional molecular wire with odd number of atoms. The wire has been modelled using the Su-Schreiffer-Heeger (SSH) Hamiltonian and the current-voltage characteristics have been obtained using the Landauer's formalism. In the presence of strong electron-lattice coupling, one finds that there are regions of negative differential resistance (NDR) at some critical bias, due to the degeneracy in the energies of the frontier molecular orbitals. The presence of the applied bias and the electron-lattice coupling results in the delocalization of these low-lying molecular states leading to the NDR behaviour.

4 illus, 24 ref

013230   Joshi V (Dept. STOPWORD Phys, Nowrosjee Wadia Coll, Pune-411 001) : Physics of musical instruments. Phys Educ 2004, 21(3-4), 163-9.

Among stringed instruments the intensity of the harmonics present in the notes produced depends upon whether the string is plucked or bowed or it is struck. The tonal quality of the sound depends on this factor and also many others which makes each musical instrument to have its unique characteristics. Discusses musical instruments such as violin, sarangi, dilruba, (bowed stringed instruments) and the various factors important from the point of their quality.

1 illus, 6 ref

013229   Jana P K;Nandi S C (Dep STOPWORD Chem, Inst of Educ (PG) for Women, Chandernagore, Hooghly-712 138) : Depletion of ozone and its effect on night airglow intensity of Na 5893A° at New Delhi (29°N, 77°E) and Halley Bay(76°S, 27°W). Indian J Phys 2005, 79(11), 1313-17.

The effect of O₃ depletion on night airglow emission of Na 5893A° line at New Delhi (29°N, 77°E) and Halley Bay (76°S, 27°W), a British Antarctic Survey Station has been presecuted. Calculations based on chemical kinetics reveal that the airglow intensity of Na 5893A° line is also affected due to ozone decline. The nature of yearly variation and seasonal variation of intensity of Na 5893A° line for the above two stations have been studied and compared. It is observed that the rate of decrease of yearly intensity of Na 5893A° line is comparatively more at Halley Bay due to dramatic decrease of Antarctic O₃ concentration. A possible explanation for the dramatic decrease of Antarctic O₃ concentration is also mentioned.

3 illus, 3 tables, 11 ref

013228   Jana D (Dep STOPWORD Phys, Univ Coll of Sci and Technol Univ of Calcutta, 92 APC Road, Kolkata-700 009, Email: d.jana@cucc.ernet.in) : Thermodynamics of N ising spins on n vertices of regular polygon. Phys Educ 2004, 21(3-4), 153-61.

Describes the two simple toy examples of Ising systems in one dimension space whose thermodynamics can be calculated exactly. Besides, this small finite system can show some important property of a large thermodynamic system in one dimensional space. These systems do not show spontaneous magnetization at any finite non-zero temperature. The above two models to regular polygon having N vertices. The basic features of the phase transition in one dimension can be demonstrated by these simple mathematically tractable models.

2 tables, 9 ref

013227   Hegde M S;Nagaveni K;Roy S (Solid St STOPWORD Structural Chem Unit, Indian Inst of Sci, Bangalore-560 012, Email: mshegde@sscu. iisc.ernet.in) : Synthesis, structure and photocatalytic activity of nano TiO₂ and nano Ti_1-x M_xO_{2-δ (M = Cu, Fe Pt, Pd, V, W, Ce, Zr).} Pramana J Phys 2005, 65(4), 641-5.

Synthesizes 5-7 nm size, highly crystalline TiO?2 which absorbs radiation in the visible region of solar spectrum. The material shows higher photocatalytic activity both in UV and visible region of the solar radiation compared to commercial Degussa P25 TiO₂. Transition metal ion substitution for Ti⁴⁺ creates mid-gap states which act as recombination centers for electron-hole induced by photons thus reducing photocatalytic activity. However, Pt, Pd and Cu ion substituted TiO₂ are excellent CO oxidation and NO reduction catalysts at temperatures less than 100°C.

2 illus, 13 ref

013226   Gupta V;Mozumdar S;Chowdhuri A;Sreenivas K (Dep STOPWORD Phys STOPWORD Astrophys, Univ of Delhi, Delhi-110 007, Email: subho@bol.net.in) : Influence of CuO catalyst in the nanoscale range on SnO₂ surface for H₂S gas sensing applications. Pramana J Phys 2005, 65(4), 647-52.

Dispersal of CuO catalyst on the surface of the semiconducting SnO₂ film is found to be of vital importance for improving the sensitivity and the response speed of a SnO₂ gas sensor for H₂S gas detection. Ultra-thin CuO islands (8 nm thin and 0.6 mm diameter) prepared by evaporating Cu through a mesh and subsequent oxidation yield a fast response speed and recovery. Ultimately nanoparticles of Cu (average size = 15 nm) prepared by a chemical technique using a reverse micelle method involving the reduction of Cu(NO₃)2 by NaBH₄ exhibited Significant improvement in the gas sensing characteristics of SnO₂ films. A fast response speed of <126>14 s and a recovery time of <126>60 s for trace level <126>20 ppm H₂S gas detection have been recorded. The sensor operating temperature (130°C) is low and the sensitivity (S = 2.06 x 10³) is high. It is found that the spreading over of CuO catalyst in the nanoscale range on the surface of SnO₂ allows effective removal of excess adsorbed oxygen from the uncovered SnO₂ surface due to spill over of hydrogen dissociated from the H₂S-CuO interaction.

6 illus, 2 tables, 5 ref

013225   Goud R V S;Sharmila D (Dep STOPWORD USIC, Acharya Nagarjuna Univ, NagarjunaNagar-522 510) : Dielectric characterization in the vicinity of SmA-SmC* phase transition in a room temperature ferroelectric liquid crystal. Bull pure appl Sci-Sect D 2005, 24(1), 41-9.

Dielectric behavior exhibited by a room temperature ferroelectric liquid crystal close to smectic-A to smectic-C* (SmA - SmC*) phase transition is studied in the frequency range of 5 Hz to 13 MHz. The dielectric permittivity and loss factor at phase transition temperature, the bias dependence of goldstone mode dielectric permitivity, the cole-cole plots of soft mode in SmA, goldstone mode and soft mode in SmC* were studied. The dielectric dispersion in the vicinity of SmA-SmC* is detailed to measure relaxation frequencies during soft mode in smectic-A, soft mode and goldstone mode in smectic-C* phases.

4 tables, 12 ref

013224   Gopi Krishna N;Kishan Rao K (Dep STOPWORD Phys, Kakatiya Univ, Warangal-506 009, Email: nallacheruvu_gopi@yahoo.com ) : Microhardness and Debye temperatures of some rare earth HCP metals. Bull pure appl Sci-Sect D 2004, 23(2), 97-101.

In view of the discrepancies in the available information on the hardness of rare earth metals, systematic studies on hardness have been carried out on highly pure and well-characterized samples of gadolinium (Gd), terbium (Tb), dysprosium (Dy), erbium (Er), lutetium (Lu) and yttrium (Y) using Vicker's pyramidal indenter and the true hardness has been estimated. The Debye temperatures of these metals have been estimated from the hardness and are compared with those obtained from specific heats, elastic constants and X-ray intensity measurements.

3 illus, 12 ref

013223   Gokhale B G (NO, , A 203, C.I. Homes, Opp. Mata Mandir, South T.T. Nagar, Bhopal-462 003) : On the use of muscovite mica in bent crystal transmission X-ray spectrographs. Phys Educ 2004, 21(3-4), 175-87.

It has been pointed out that besides the (100) and (<96>201) planes of muscovite mica, there are number of other planes which can be profitably employed in a bent crystal (Cauchois) X-ray spectrograph. Formulas are given for the calculation of their interplaner spacings d (hkl), their inclinations α(hkl) with the normal to the mica sheet, as well as for the structure factors F(hkl) for these planes. Tables are given for the values of these quantities, as also for the dispersion in xu/mm in the region of MoKα₁ for a large number of planes belonging to the (100), (3<96>10), (1<96>10) and (010) zones of muscovite mica. Finally, attention is drawn to a number of hitherto unused planes which could be of interest for use in the Cauchois spectrograph.

4 illus, 5 tables, 15 ref

013222   Gautam U K;Sardar K;Deepak F L;Rao C N R (Chem STOPWORD Phys STOPWORD Mater Unit STOPWORD CSIR Cent STOPWORD Ex, Jawaharlal Nehru Cent for Advd Scientific Res, Jakkur P.O., Bangalore-560 064, Email: cnrrao@jncasr.ac.in) : Soft chemical routes to semiconductor nanostructures. Pramana J Phys 2005, 65(4), 549-64.

Soft chemistry has emerged as an important means of generating nanocrystals, nanowires and other nanostructures of semiconducting materials. Author described the synthesis of CdS and other metal chalcogenide nanocrystals by a solvothermal route. It describes the synthesis of nanocrystals of AlN, GaN and InN by the reaction of hexamethyldisilazane with the corresponding metal chloride or metal cupferronate under solvothermal conditions. Nanowires of Se and Te have been obtained by a self-seeding solution-based method. A single source precursor based on urea complexes of metal chlorides gives rise to metal nitride nanocrystals, nanowires and nanotubes. The liquid liquid interface provides an excellent medium for preparing single-crystalline films of metal chalcogenides.

11 illus, 29 ref

013221   Dubey P;Muthukumaran D;Dash S;Mukhupadhyay R; Sarkar S (Dep STOPWORD Chem, Indian Inst of Technol, Kanpur-208 016, Email: abya@iitk.ac.in) : Synthesis and characterization of water-soluble carbon nanotubes from mustard soot. Pramana J Phys 2005, 65(4), 681-97.

Carbon nanotubes (CNT) has been synthesized by pyrolysing mustard oil using an oil lamp. It was made water-soluble (wsCNT) through oxidative treatment by dilute nitric acid and was characterized by SEM, AFM, XRD, Raman and FTIR spectroscopy. The synthesized wsCNT showed the presence of several junctions and defects in it. The presence of curved graphene structure (sp²) with frequent sp³ hybridized carbon is found to be responsible for the observed defects. These defects along with the presence of di- and tri-podal junctions showed interesting magnetic properties of carbon radicals formed by spin frustration. This trapped carbon radical showed ESR signal in aqueous solution and was very stable even under drastic treatment by strong oxidizing or reducing agents. Oxidative acid treatment of CNT introduced several carboxylic acid group functionalities in wsCNT along with the nicking of the CNT at different lengths with varied molecular weight. To evaluate molecular weights of these wsCNTs, an innovative method like gel electrophoresis using high molecular weight DNA as marker was introduced.

14 illus, 52 ref

013220   Devlal K;Johri U C;Shrivastva N;Bhattacharya B (Dep STOPWORD Phys, G.B. Pant Univ of Agric & Technol, Pantnagar-263 145) : Electrical properties of CdS dispersed ammonium alum composite solid electrolyte. Indian J Phys 2005, 79(11), 1275-8.

Solid electrolytes (superionic solids) are a class of materials of great interest for its applications in the devices like solid-state batteries, fuel cells, sensors, electrochemical devices. CdS dispersed ammonium alum composite is studied for its electrical properties. The ionic conductivity of this kind of composite depends on the percentage of CdS by weight in the alum. The conductivity of composite initially increases to a maximum and then decreases gradually. The transference number measured for these samples give the information about ionic conductivity, which decreases with increase of CdS. The study also shows if the material absorbs moisture, then its conductivity is enhanced linearly. Thus, the conductivity of such type of materials strongly depends on the humidity of the surroundings and the material can be used for humidity sensor.

4 illus, 2 tables, 20 ref