013239   Datta S;Roy A (Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore-560 080, Email: aroy@rri.res.in) : Experimental studies of the transient fluctuation theorem using liquid crystals. Pramana J Phys 2009, 72(5), 797-804.

In a thermodynamical process, the dissipation or production of entropy can only be positive or zero, according to the second law of thermodynamics. However, the laws of thermodynamics are applicable to large systems in the thermodynamic limit. Recently a fluctuation theorem, known as the transient fluctuation theorem (TFT), which generalizes the second law of thermodynamics to small systems has been proposed. This theorem has been tested in small systems such as a colloidal particle in an optical trap. We report for the first time an analogous experimental study of TFT in a spatially extended system using liquid crystals.

3 illus, 18 ref

013238   Damle R;Kulkarni P N;Bhat S V (Physics Dep, Bangalore Univ, Bangalore-560 056, Email: ramkrishnadamle@bub.ernet.in) : Effect of composition, electron irradiation and quenching on ionic conductivity in a new solid polymer electrolyte: (PEG)_xNH₄I. Pramana J Phys 2009, 72(3), 555-68.

Prepared, characterized and investigated a new PEG-2000 based solid polymer electrolyte (PEG) χNH₄I. Ionic conductivity measurements have been made as a function of salt concentration as well as temperature in the range 265-330 K. Selected compositions of the electrolyte were exposed to a beam of 8 MeV electrons to an accumulated dose of 10 kGy to study the effect on ionic conductivity. The electrolyte samples were also quenched at liquid nitrogen temperature and conductivity measurements were made. The ionic conductivity at room temperature exhibits a characteristic double peak for the composition x = 20 and 70. Both electron beam irradiation and quenching at low temperature have resulted in an increase in conductivity by 1-2 orders of magnitude. The enhancement of conductivity upon irradiation and quenching is interpreted as due to an increase in amorphous region and decrease in crystallinity of the electrolyte. DSC and proton NMR measurements also support this conclusion.

10 illus, 4 tables, 40 ref

013237   Chaurasia S;Leshma P;Tripathi S;Murali C G; Munda D S;Sharma S M;Kailas S;Gupta N K;Dhareshwar L J (High Pressure and Synchrotron Radiation Physics Div, Physics Group, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : Simultaneous measurement of particle velocity and shock velocity for megabar laser driven shock studies. BARC Newsl 2010, (NULL), 13-21.

Studies of hydrodynamics of the laser driven targets are important for various applications. Determination of equation-of-state (EOS) of materials subjected to multi-Mega bar pressure by laser ablation involves the simultaneous measurements of shock velocity and particle velocity. We have developed an accurate technique to achieve this. Multi-frame optical shadowgraphy technique coupled with an optical streak camera has been used to measure shock pressure with an accuracy of +/- 7%. Free surface velocity (particle velocity) of a laser driven target foil has been measured with multi-frame optical shadowgraph technique and shock velocity is measured with the optical streak camera. The shock pressure measured with the laser intensity up to 2.5 x 10¹⁴ W/cm² is about 25 Mbar in aluminum foils.

7 illus, 9 ref

013236   Chaudhary A K;Molla A;Asfaw A (Advanced Centre of Research in High Energy Materials, P-002, Science Complex, Hyderabad Univ, Hyderabad-500 046, Email: anilphys@yahoo.com) : Measurement of refractive index of biaxial potassium titanyl phosphate crystal plate using reflection spectroscopic ellipsometry technique. Pramana J Phys 2009, 72(4), 731-41.

Reports the measurement of refractive indices and anisotropic absorption coefficients of biaxial potassium titanyl phosphate (KTP) crystal in the form of thin plate using reflection ellipsometry technique. This experiment is designed in the Graduate Optics Laboratory of the Addis Ababa University and He-Ne laser (λ = 632.8 run), diode laser (λ = 670.0 nm) and temperature-tuned diode laser (λ = 804.4 and 808.4 nm), respectively have been employed as source. The experimental data for n_xn_y are fitted to the Marquardt-Levenberg theoretical model of curve fitting. The obtained experimental data of refractive indices are compared with different existing theoretical and experimental values of KTP crystals and found to be in good agreement with them.

4 illus, 1 table, 26 ref

013235   Chandrachud P;Joshi K;Krishnamurty S;Kanhere D G (Physics Dep, Pune Univ, Ganeshkhind, Pune-411 007, Email: kanhere@unipune.ernet.in) : Stability of gold cages (Au16 and Au17) at finite temperature. Pramana J Phys 2009, 72(5), 845-55.

Employed ab initio molecular dynamics to investigate the stability of the smallest gold cages, namely Au₁₆ and Au₁₇, at finite temperatures. First, we obtain the ground state structure along with at least 50 distinct isomers for both the clusters. This is followed by the finite temperature simulations of these clusters. Each cluster is maintained at 12 different temperatures for a time period of at least 150 ps. Thus, the total simulation time is of the order of 2.4 ns for each cluster. Observed that the cages are stable at least up to 850 K. Although both clusters melt around the same temperature, i.e. around 900 K, Au₁₇ shows a peak in the heat capacity curve in contrast to the broad peak seen for Au₁₆.

6 illus, 53 ref

013234   Chandra H;Vyas G D (NO, Physical Research Laboratory, Navrangpura, Ahmedabad-380 009, Email: hchandra@prl.res.in) : Abnormally low F-layer ionization over Ahmedabad during the night of 26-27 November 1984. Indian J Radio Space Phys 2010, 39(6), 346-52.

A case study of the critical frequency of F2 layer (foF2) over Ahmedabad (Geog latitude 23°N, longitude 72.4°E) during 17-30 November 1984, a geomagnetic quiet period, has been carried out. An interesting feature observed is very low values of foF2 (2.3 MHz) around 2100 hrs LT on 26 November. The quarter hourly ionograms during the night of 26-27 November 1984 were subjected to true height -analysis to study the features of F-layer. The variations of hm show rapid rise of about 100 km at 2100 hrs LT followed by rapid fall of similar magnitude at 0100 hrs LT. The quasi-periodic variations with periods of about 90 min are also seen. The variation of the semi-thickness of F-layer also shows similar wave-like features. The wave-like perturbations of about 12 km in F-layer height and about 16 km in the semi-thickness of F-layer point to gravity waves in neutral winds and temperature as their source.

7 illus, 25 ref

013233   Chandan A;Singh S;Bharti A;Khosa S K (Physics Dep, Jammu and Kashmir Univ, Jammu-180 006, Email: arunbharti_2003@yahoo.co.in) : Microscopic study of low-lying yrast spectra and deformation systematics in neutron-rich <. Pramana J Phys 2009, 72(4), 657-68.

Variation-after-projection (VAP) calculations in conjunction with Hartree-Bogoliubov (HB) ansatz have been carried out for A = 98-106 strontium isotopes. In this framework, the yrast spectra with J^II ≥ 10+, B(E2) transition probabilities, quadrupole deformation parameter and occupation numbers for various shell model orbits have been obtained. The results of the calculation for yrast spectra give an indication that it is important to include the hexadecapole-hexadecapole component of the two-body interaction for obtaining various nuclear structure quantities in Sr isotopes. Besides this, it is also found that the simultaneous polarization of P₃/₂ and f₅/₂ proton subshells is a significant factor in making a sizeable contribution to the deformation in neutron-rich Sr isotopes.

1 illus, 5 tables, 34 ref

013232   Bizjak G;Lindemanna M;Sperling A;Sauter G (Laboratory of Lighting Engineering and Photometry, University of Ljubljana, Faculty of Electrical Engineering, Trzaska 25, SI-1000, Email: grega.bizjak@fe.uni-lj.si) : Determination of stray light at the PTB goniophotometer facility. MAPAN 2009, 24(3), 163-74.

For improved luminous flux measurements, the Physikalisch-Technische Bundesanstalt (PTB) was equipped with a new robotic goniophotometer. In order to characterize this instrument, to reduce the combined measurement uncertainty, and to determine the respective uncertainty components, the influence of stray light on the measurement results was investigated. Considering the specific structure of the robotic goniophotometer, stray light was measured on-line by means of a purpose-built "back-looking" photometer. By this means, the influence of the luminous intensity distn1JUtion of each individual light source with regard to its stray light could be considered. Before the first experimental application, the invented procedure was tested by means of calculations using mathematical models. In this paper, the mathematical model for the calculation of stray light in the goniophotometer room is presented together with the calculation results and the results of the first measurements. The achieved results indicate that the recommended stray light measurements can decrease the total relative standard measurement uncertainty of luminous flux measurements down to 2 x 10^-3.

12 illus, 3 tables, 3 ref

013231   Bannur V M;Thayyullathil R B (Physics Dep, Calicut Univ, Kozhikode-673 635, Email: vmbannur@yahoo.co.in) : Formulation of statistical mechanics for chaotic systems. Pramana J Phys 2009, 72(2), 315-23.

Formulates the statistical mechanics of chaotic system with few degrees of freedom and investigated the quartic oscillator system using microcanonical and canonical ensembles. Results of statistical mechanics are numerically verified by considering the dynamical evolution of quartic oscillator system with two degrees of freedom.

1 illus, 18 ref

013230   Banerjee P;Thorate P P (National Physical Laboratory (NPLI), Council of Scientific and Industr, , New Delhi-110 012, Email: thoratpp@mail.nplindia.org) : Evaluation of performance of GPS receiver in CRRI network survey vehicle. MAPAN 2009, 24(4), 233-40.

In connection with some sponsored project, Central Road Research Institute (CRRI), New Delhi procured an advanced Network Survey Vehicle (NSV), which is equipped with several sensors including a GPS receiver and a computer. The success of this project primarily depends on the accuracy of the extracted coordinates collected by a GPS receiver housed in NSV. To evaluate the performance of the GPS receiver, a special experiment in a campaign mode was conducted in NPL, New Delhi. This paper elaborates the experimental plan and discusses the analysis of the data.

4 illus, 1 table, 7 ref

013229   Bali Raj;Pareek U K (Mathematics Dep, Rajasthan Univ, Jaipur-302 004, Email: balirs@yahoo.co.in) : Bianchi type V magnetized string dust cosmological models with Petrov-type degenerate. Pramana J Phys 2009, 72(5), 787-96.

Bianchi Type V massive string cosmological models with free gravitational field of Petrov Type degenerate in the presence of magnetic field with variable magnetic permeability are investigated. The magnetic field is due to an electric current produced along the x-axis. The F₂₃ is the only non-vanishing component of electromagnetic field tensor F_ij. Maxwell's equations F_[ij;k] = 0 and F^ij_j = 0 are satisfied by F₂₃ = constant. The behaviour of the model in the presence and absence of magnetic field and other physical aspects are also discussed.

30 ref

013228   Bal S;Bose M (Physics Dep, Jadavpur Univ, Kolkata-700 032, Email: mridulbose@yahoo.co.in) : Stimulated brillouin scattering of an electromagnetic wave in weakly magnetized plasma with variably charged dust particles. Pramana J Phys 2009, 72(4), 787-92.

Investigated analytically the stimulated Brillouin scattering (SBS) of an electromagnetic wave in non-dissipative weakly magnetized plasma in the presence of dust particles with variable charge.

1 illus, 12 ref

013227   Badr A M;Elshaikh H A;Ashraf I M (Physics Dep, Faculty of Science (Aswan), South Valley Univ, Egypt, Email: dr_haroun@yahoo.com) : Crystal growth, electrical and photophysical properties of Tl₂S layered single crystals. Pramana J Phys 2009, 72(5), 871-85.

The Tl₂S compound was prepared in a single crystal form using a special local technique, and the obtained crystals were analysed by X-ray diffraction. For the resultant crystals, the electrical properties (electrical conductivity and Hall effect) and steady-state photoconductivity were elucidated in this work. The electrical measurements extend from 170 to 430 K, where it was found that σ_⊥ = 8.82 x 10^-5 Sm^-1 when current flow direction makes right angle to the cleavage plane of the crystals. In the same range of temperatures, it was found that σ|| = 4.73 x 10^-5 Sm^-1 when the current flow is parallel to the cleavage plane. In line with the investigated range of temperatures, the widths of the band gaps were calculated and discussed as also the results of the electrical conductivity and Hall effect measurements. In addition, the anisotropy of the electrical conductivity (σ_⊥/σ||) for the obtained crystals was also studied in this work. Finally the photosensitivity was calculated for different levels of illumination as a result of the photoconductivity measurements, which showed that the recombination process in single crystals is a monomolecular process.

11 illus, 26 ref

013226   Ali S G;Talukdar B;Saha A (Physics Dep, Visva-Bharati Univ, Santiniketan-731 235, Email: binoy123@bsnl.in) : Effect of three-body atomic interaction and optical lattice on solitons in quasi-one-dimensional Bose-Einstein condensate. Pramana J Phys 2009, 72(2), 445-50.

Makes use of a coordinate-free approach to implement Vakhitov-Kolokolov criterion for stability analysis in order to study the effects of three-body atomic recombi-nation and lattice potential on the matter-wave bright solitons formed in Bose-Einstein condensates. We analytically demonstrate that (i) the critical number of atoms in a stable BEC soliton is just half the number of atoms in a marginally stable Townes-like soliton and (ii) an additive optical lattice potential further reduces this number by a factor of √1 - bg₃ with g₃, the coupling constant of the lattice potential and b = 0.7301.

1 illus, 10 ref

013225   Ahmad S;Aggarwal R;Pal B;Govil A K;Banerjee P (National Physical Laboratory (NPLI), Council of Scientific and Industr, , New Delhi-110 012, Email: ahmads@nplindin.org) : Validation of RF power standard in the frequency ange of 100 MHz to 18 GHz by an inter laboratory data comparison. MAPAN 2009, 24(4), 247-53.

Radio frequency (RF) power is one of the most important quantities in RF metrology. An inter laboratory data comparison of RF power for the validation of a coaxial microcalorimeter has been carried out behveen Physikalisch- Technische Bundesanstalt (PTB-Germany) and National Physical Laboratory India (NPLI). A coaxial thermistor mount equipped with type N connector is used for this intercomparison. The results show good agreement in measuring the effective efficiency of the coaxial thermistor mount between the two laboratories within their claimed expanded uncertainty. It confirms the equivalence of national standards for RF power in the frequency range of 100 MHz to 18 GHz.

3 illus, 3 tables, 8 ref

012254   Yadav R P;Darshan Dev;Vinod Kumar (Physics Dep, Govt. P.G. College, Bisalpur (Pilibhit)-262 201, Email: rpyadav93@pphysics@yahoo.co.in) : Energy consideration in shock waves moving in rotating atmosphere. Ultra Scient phys Sci 2009, 21(1), 199-206.

Adiabatic and isothermal propagations of spherical shock waves produced due to a nuclear explosion have been studied using the energy hypothesis of Thomas in the nonuniform atmosophere of the earth. The explosion is considered at different height, is calculated shock strength and shock velocity for adfabatic and isothermal flow. It has been found that shock strength and shock velocity in isothermal flow is smaller in comparison to adiabatic flow. It has been also found that the energy of shock waves in adiabatic flow is larger than isothermal flow. The effect angular velocity of rotation on the shock velocity and shock strength is also discussed.

4 tables, 8 ref

012253   Yadav R P;Dal Chand;Yadav M (Physics Dep, Govt. P.G. College, Bisalpur (Pilibhit)-162 201, Email: rpyadav93pphysics@yahoo.co.in) : Effect of overtaking distrubances on converging strong spherical shock waves in a rotating dusty gas. Ultra Scient phys Sci 2009, 21(1), 15-24.

In the paper effect of overtaking disturbances on the freely propagation of converging strong spherical shock through a rotating dusty gas is studied by a technique developed by Yadav. The dusty gas is assumed to be a mixture of a perfect gas and small solid particles. Assuming an initial density distribution law as ρ₀=ρ_cr^-α , where ρ_c is the density at the axis of symmetry and a a positive constant, the analytical relations for flow variables modified by overtaking disturbances are obtained. The variations of flow variables with (i) propagation distance, (ii) mass concentration of solid particles in the mixture, (iii) specific density G and (iv) angular velocity Ω, are obtained. The results obtained here are also compared with those for a freely propagating shock.

3 illus, 4 tables, 16 ref

012252   Yadav M;Chauhan D S (Physics Dep, Govt. P.G. College Kotdwara, Garhwal-246 149, Email: laxidev25@yahoo.com) : Strong cylindrical shockwaves under the influence overtaking disturbances. Ultra Scient phys Sci 2009, 21(3), 477-84.

Inclusion of effects of disturbances behind the shock waves moving in uniform and non-uniform medium modifies the approximate method used to investigate their propagation. Using modified CCW Method an attempt has been made to study the propagation of strong cylindrical shock waves including the effect of disturbances behind the shock through an ideal and rotating gas at permissible shock front locations for an arbitary initial density distribution of the form, say, ρ₀ - ρ' log(1+λr), where ρ' is the density at the axis of symmetry and ρ is non-dimensionalyzing constant. The numerical estimate of the flow variables have been computed at only on those values of propagation distance r which are permitted by the entropy distribution condition. The result obtained has been presented through graph and compared with the earlier work.

2 illus, 1 tables, 23 ref

012251   Yadav D S;Singh D (Physics Dep, Agra College, Agra-282 002, Email: dherendra0000@gmail.com) : Bond ionicity and electronic polarizability of A<. Ultra Scient phys Sci 2009, 21(1), 193-8.

Using Phillips and Van-Vechten (PVV) theory^1-3, the values of homopolar gap, ionic gap and Penn gap have been evaluated for A-C and B-C bonds in A^IIB^IVC₂^V ternary chalcopyrite semiconductors. Using the above parameters, the bond ionicity (ƒ) has been determined. The values obtained are in good agreement with the literature value. The electronic polarizabilities have also been evaluated using-the Clausius-Mossotti relation. The values are in good agreement with the ordinary sums of the polarizabilities of individual bonds.

3 tables, 19 ref

012250   Wamalwa D S;Omolo J A (Physics Dep, maseno Univ, P.O. Private Bag, Maseno, Kenya, Email: dismasw@yahoo.com) : Generalizaed relativistic dynamics in a non-inertial reference frame. Indian J Phys 2010, 84(9), 1241-55.

Generalized relativistic field equations have been derived for dynamics in a non-inertial reference frame interpreted as a Finsler space where events are specified by both spacetime coordinates and corresponding velocities (tangent vectors). The field equations follow in two alternative forms from exact general conservation laws derived through application of Cartan covariant differentiation within the framework of Finsler geometry. Velocity-dependent (curvature) terms in the field equations can account for the anisotropy of the gravitational field, together with the associated acceleration and expansion of the universe.

28 ref

012249   Ubale A U;Bargal A N (Physics Dep, Govt. Vidarbha Institute of Science and Humanities, Amravati-444 604, Email: ashokuu@yahoo.com) : Characterization of nanostructured photosensitive cadmium sulphide thin films grown by SILAR deposition technique. Indian J Phys 2010, 84(11), 1497-1507.

Paper reports the preparation of photosensitive nanostructured CdS thin films by Successive Ionic Layer Adsorption and Reaction (SILAR) method at room temperature. To obtain good quality CdS thin films, preparative conditions such as concentration of cationic and anionic precursors, adsorption and rinsing time durations etc. are optimized. The structural, optical, and electrical characterizations of the as-deposited and annealed CdS thin films were carried out using X-ray diffraction, scanning electron microscopy, optical absorption and electrical resistivity methods. The photoconductivity studies showed that the annealed films are more than that photosensitive. The TEP measurement shows that deposited films are of n-type.

12 illus, 2 tables, 18 ref

012248   Tripathi D (Physics Dep, Gujarat Univ, Ahmedabad-380 009) : Carbon and oxygen related deep acceptor states in hydrogenated n-type silicon. Natn Acad Sci Lett 2009, 32(1-2), 45-50.

Hydrogen induced changes in n-type crystalline Silicon has been investigated in infrared absorption range of 900 cm^-1 to 1600 cm^-1 to study chemical activity of hydrogen with unintentionally doped impurities, (like Carbon and Oxygen) present in n-type Silicon. Hydrogen is introduced into n-type Silicon by exposing the sample through an evaporated Pd layer to molecular hydrogen at room temperature. The I-R spectrum after hydrogenation shows growth of a peak around 1000 Cm^-1 related to Ci-Oi complexes (where i refers to interstitial sites) which are found to give rise deep acceptor like states in Silicon band gap. The forward bias C-V studies done earlier have already shown the presence of hydrogen induced acceptor like deep states in the band gap of hydrogenated n-type Silicon, which support present results.

2 illus, 1 tables, 23 ref

012247   Tiwari S N;Pandey B;Shukla S (Physics and Electronics Dep, Dr. R.M.L. Avadh Univ, Faizabad-224 001) : Qualitative analysis of two distinct wide band triple darlington amplifiers. Ultra Scient phys Sci 2009, 21(1), 117-20.

TWO distinct Modifications are proposed in the conventional circuit of Triple Darlington amplifier by adding an extra biasing resistance RD. First amplifier completely removes the problem of poor response of Triple Darlington at higher frequencies as well as provides wide band frequency response for small signals. While, the second amplifier effectively widens the frequency band. Hence the proposed small signal amplifiers can be significantly used in various commercial electronics and communication circuits.

5 illus, 11 ref

012246   Tiwari S N;Pandey B;Dwivedi A K;Shukla S (Physics and Electronics Dep, Dr. Ram Manohar Lohia Avadh Univ, Faizabad-224 001, Email: sachida_shukla@yahoo.co.in) : Development of small-signal amplifiers by placing BJT and JFET in Darlington pair configuration. Ultra Scient phys Sci 2009, 21(3), 509-14.

Darlington pair amplifier in CC/CE configuration is a useful amplifier circuits for low voltage signals. First time authors have proposed two distinct modifications in CC/CE Darlington pair amplifier by replacing one of the BJT of pair from FET and by including an extra biasing resistance RP. It was observed that one amplifier produce high voltage gain with improved bandwidth while another produces extremely wide bandwidth with consistent voltage gain. Such amplifiers with distinct behaviour may be very useful for amplification of small signals in mid frequency or wide frequency bands.

7 illus, 11 ref

012245   Tiwari R K;Shukla H P (Physics and Electronics Dep, Dr. R.M.L. Awadh Univ, Faizabad) : Introduction to emerging reversible logic technology and it's applications. Ultra Scient phys Sci 2009, 21(3), 461-6.

In the recent years, reversible logic has emerged as a promising technology having its applications in low power CMOS, Quantum Computing, Nanotechnology and Optical Computing. Mostly in every Computing Systems bit information is either erased or changes its status every time it performs a logic operation. This erasure is done very inefficiently and heat is dissipated in each bit of erasing. Energy efficient digital circuits used in computing systems are being developed using Reversible Logic Technique. In this paper concepts of various reversible logic gate has been described which may be used as building blocks of digital circuits used in computing system.

16 illus, 13 ref

012244   Tiwari R K;Mishra G R;Misra M (Physics and Electronics Dep, Dr. R.M.L. Avadh Univ, Faizabad) : High performance low voltage CMOS differential amplifier. Ultra Scient phys Sci 2009, 21(3), 493-8.

Differential amplifiers play an important role in the analog circuit design because of their excellent performance as input amplifiers and the straightforward application with the possibility of feedback to the input. The differential amplifier circuit characterized in terms of self-bias capability, common-mode rejection, voltage gain, and the gain-bandwidth product. In this paper a new model for high performance low voltage CMOS differential amplifier has been proposed. This model is simulated using SPICE simulator and optimized device parameter with 25 micron CMOS technology.

3 illus, 22 ref

012243   Thapa R;Saha B;Goswami S;Chattopdhyay K K (Physics Dep, Center for Nanoscience and Technology, Jadavpur Univ, Kolkata-700 032, Email: kalyan_chattopadhyay@yahoo.com) : Field emission and dielectric properties of AIN films prepared by DC sputtering technique at different substrate temperatures. Indian J Phys 2010, 84(10), 1347-54.

Nanocrystalline AIN thin films were prepared via DC sputtering technique at different substrate temperature. The crystal orientation and particle size of aluminum nitride thin films were investigated by XRD analysis. Study indicated that the sample contained pure phase hexagonal AIN nanoparticles with a single peak corresponding to the (100) planes. The peak at 665 cm^-1 in the FTIR spectrum of film was assigned to the LO phonon of hexagonal AIN. The particle size of the film, prepared at substrate temperature 200°C was about 9.5 nm, as investigated by atomic force microscope. Field emission study indicated that it can be used as a good field emitter. Turn-on field (E_to) of 15.02 V/μm was observed for the AIN films synthesized at substrate temperature 200 °C. Dielectric constant of the AIN film was found nearly independent of frequencies in the measured frequency range 1 KHz to 1 MHz, i.e. in the audio frequency range. The values of dielectric constant (ε) were 10.07, 9.46 and 8.65 for the film prepared at 70°C, 150°C and 200°C, respectively, at frequency 1 KHz.

6 illus, 21 ref

012242   Thakkar K;Parmar A;Patel B;Vinodkumar P C (Physics Dep, Sardar Patel Univ, Vallabh Vidyanagar-388 120, Email: p.c.vinodkumar@gmail.com) : Magnetic moments of light flavour baryons in a hypercentral quark model. Prajna 2010, 18(1-4), 157-62.

The light flavour baryons are studied within the quark model using the hyper central description of the three-body system. The confinement potential is assumed as hypercentral coulomb plus power potential ( hCPP_v ) with power index V. The masses and magnetic moments of light flavour baryons are computed for different power index, V starting from 0.5 to 1.5. The predicted masses and magnetic moments are found to attain a saturated value with respect to variation in V beyond the power index V <62> 1.0.

2 illus, 4 tables, 52 ref

012241   Tandon P N;Shikha (H.B.T.I. Kanpur, India and Brunei Darussalam Univ, Bareilly College, Bereilly) : Megnetohydrodynamics flow of a viscous fluid through an infinite circular region bounded by a porous medium fully saturated an other viscous fluid. Ultra Scient phys Sci 2009, 21(3), 675-82.

Presented herein are the studies of the effect of applied magnetic field on two region flows: one a clear fluid flowing in an infinite circular region and in porous region surrounding the circular region. Two cases have been considered - the porous region is bounded and unbounded. Analysis confirms the positive effects of reducing the velocities in both regions. The effect of slip parameter is also to decrease the velocities in both regions at fixed values of applied magnetic field identified by the parameter Mo. The effect of increasing values of parameter (3 is to decrease the velocity in clear fluid whereas the results are reversed in porous region. In the limiting case i.e. in absence the magnetic field, the results agree with Srivastava et.al.⁹ in the first case only. For other results the particular cases are not available in literature.

7 illus, 22 ref

012240   Talware R B;Surywanshi D B;Kumbharkhane A C; Mehrotra S C (NO, Physical Sciences School, Swami Ramanand Teerth Marathwada Univ, Nanded-431 606, Email: akumbharkhane@yahoo.co.in) : Dielectric behaviour of aqueous CsCI solutions. Indian J Phys 2011, 85(2), 301-10.

Complex dielectric permittivity spectra, in the frequency range 10 MHz to 20 GHz are reported for aqueous cesium chloride (CsCI) solutions at 25°C using time domain reflectometry technique. The static dielectric constant, relaxation time and conductivity have been determined using nonlinear least squares fit method. From the static dielectric constant, hydration numbers were determined by using measured solutions density at different concentrations.

8 illus, 2 tables, 20 ref

012239   Sunita Devi;Srivastva M (Chemistry Dep, Meerut College, Meerut-250 005, Email: drmsrivastava_56@yahoo.com) : Solgel synthesis and structural characterization of silver-silica nanocomposites. Indian J Phys 2010, 84(11), 1561-6.

The solgel process has been successfully used to prepare silver/silica nanocomposites. After drying in air at 50°C for 30 min, samples were heat treated in air, at 100, 200, 400 and 500°C for the formation of silver nanoparticles. Evolution of silver nano-particles in the amorphous SiO₂ matrix as a function of annealing temperature has been studied. Characterizations were made by X-ray diffraction, ultraviolet-visible, and infrared spectroscopy. Mechanisms of silver clusters formation in the densified silica matrix with respect to thermal treatment are discussed.

3 illus, 21 ref

012238   Sumesh C K;Patel K D;Pathak V M;Srivastava R (Physics Dep, Faculty of Technology and Engineering, Charotar Sciences and Technolog, Changa, Anand-388 421, Email: cksumesh.cv@ecchanga.ac.in) : Native defects in MoSe₂ crystals grown by direct vapor transport. Prajna 2010, 18(1-4), 129-31.

The presence of native defects in crystals of MoSe₂ grown by direct vapour transport has been investigated. The XRD and EDAX shows the presence of MoO₂, MoO₃, Se and SeO₂ along with MoSe₂. The formula assigned to grown crystals is MoSe_2.03 accounting for excess of selenium as seen from EDAX. This excess in selenium may be attributed to the use of molybdenum in formation of MoO₂ and MoO₃ with residual oxygen in the ampoule which outweighs slightly the use of selenium in formation of SeO2 in addition to unreacted selenium. The n-type conductivity of grown crystals can be attributed to the compensating nature of defects incorporated during growth. The extrinsic electrical behavior of MoSe₂ is therefore ascribed to the presence of both donors and acceptor impurities originating from the defect structure of MoSe₂ crystals.

3 illus, 20 ref

012237   Singh M K;Pathak R;Singh V (Physics Dep, Tilakdhari Postgraduate College, Jaunpur-222 002, Email: venkaz@yahoo.com ) : Characteristics of alpha projectile fragments emission in interaction of nuclei with emulsion. Indian J Phys 2010, 84(9), 1257-73.

The properties of the relativistic alpha fragments produced in interactions of 84Kr at around 1 A GeV in nuclear emulsion are investigated. The experimental results are compared with the similar results obtained from various projectiles with emulsion interactions at different energies. The total, partial nuclear cross-sections and production rates of alpha fragmentation channels in relativistic nucleus-nucleus collisions and their dependence on the mass number and initial energy of the incident projectile nucleus are investigated. The yields of multiple alpha fragments emitted from the interactions of projectile nuclei with the nuclei of light, medium and heavy target groups of emulsion-detector are discussed and they indicate that the projectile-breakup mechanism seems to be free from the target mass number. It is found that the multiplicity distributions of alpha fragments are well described by the Koba-Nielsen-Olesen (KNO) scaling presentation. The mean multiplicities of the freshly produced or newly created charged secondary particles, normally known as shower and secondary particles associated with target in the events where the emission of alpha fragments were accompanied by heavy projectile fragments having Z≥ 3 seem to be constant as the alpha fragments multiplicity increases, and exhibit a behavior independent of the alpha fragments multiplicity.

8 illus, 3 tables, 27 ref

012236   Singh M (Physics Dep, Jagdam College, Chapra) : D.C. electric field mill for measuting vertical potential gradient of atmosphere. Ultra Scient phys Sci 2009, 21(1), 215-22.

The design, fabrication and calibration of a d.c. electric field mill to measure electrostatic field of disturbed weather conditions of the atmosphere has been described. The electrical noise and complexity have been reduced by introducing the penchart recorder directly through a Teflon coated coaxial cable in place of pushpull d.c. amplifier, potentiometer and a galvanometer as used by Gunn³. Provision has been made for selecting the desired sensitivity of the electric field meter. The electric field mill provides a reliable output even in periods of severe conditions of the atmosphere.

3 illus, 6 ref

012235   Singh K;Shrivastava P K (Physics Dep, Govt. P.G. Science College, Rewa, Madhya Pradesh, Email: pankj_in_2001@rediffmail.com) : Average characteristics of cosmic ray daily variation for the period of 1995 to 2006. Ultra Scient phys Sci 2009, 21(3), 533-6.

Cosmic ray neutron monitor data of Haleakala station are used for an extensive study of cosmic ray diurnal and semi-diurnal variation for the period of 1995 to 2006. We have derived an average characteristics of first two harmonics of cosmic ray daily variation. The amplitude of the diurnal/semi diurnal variation has an eleven year cycle. Time of maxima exhibits a 22 year cycle for diurnal anisotropy.

2 illus, 7 ref

012234   Singh J;Shyampati;Lalmani (Physics Dep, G.G.M. Science College, Canal Road, Jammu) : Pulsing VLF hiss emissions observed at low latitude Indian ground station Jammu. Ultra Scient phys Sci 2009, 21(3), 525-32.

The pulsing hiss emissions recorded during daytime in the frequency range of 50 Hz -15 kHz at low latitude station Jammu (geomag. lat. = 22° 26 N; L = 1.17) are reported. The reported pulsing VLF emissions is a rare phenomena at low latitudes and the spectrograms of pulsing VLF hiss emissions clearly show band limited spectrums regularly pulsing with almost equal period of the order of few seconds in the frequency range of <126> 3 to 8 kHz. Generation and propagation mechanism of these emissions are briefly discussed.

2 illus, 12 ref

012233   Singh D;Jaggi N;Nafa Singh (Physics Dep, Dyal Singh College, Karnal-132 001, Email: ds_kuk@yahoo.com) : Vibrational analysis of 1-chlorooctane. Indian J Phys 2010, 84(9), 1163-76.

The organic compound 1-chlorooctane exists in liquid state at ambient temperatures and has numerous synthetic applications. Fourier transform infrared and Raman spectra of this molecule have been recorded in the range of 4000-400 cm^-1 and 3500-200 cm^-1, respectively. A detailed vibrational analysis in terms of assignment of the observed frequencies of this molecule for its four most probable conformations in liquid phase, having symmetries C_s and C***,, has been done using normal co-ordinate calculations. The force-field transferred from already studied lower chain chloro-alkanes is subjected to refinement so as to fit the observed infrared and Raman frequencies with those of calculated ones. The potential energy distribution has also been calculated for each mode of vibration of the molecule for the most probable conformations present in its liquid phase.

3 illus, 1 table, 36 ref

012232   Singh A;Shrivastava A;Dubey P;Tiwari A K (Physics Dep, A.P.S. Univ, Rewa-486 003) : Interplanetary disturbances effect on geomagnetic field. Ultra Scient phys Sci 2009, 21(3), 667-74.

The solar output and its variations have been quantified by several interplanetary parameters generated for near earth space at 1 AU. Earlier studies had established the relative role of the solar wind speed, as well as the magnitude of the interplanetary magnetic field in generating magnetic field disturbances. The high speed solar wind streams were studied and sorted for solar cycle 22 &23 on the basis of strict selection criteria. In the study period of solar cycles 22 and 23, a total number of 294 high-speed solar wind stream (HSWS) events have been sorted out in which 116 HSWS events were observed in solar cycle 22, whereas 178 HSWS events have been observed in solar cycle 23. 93 HSWS events were registered to be flare-generated stream events where as 201 HSWS events are registered to be coronal hole associated stream events during the whole period of solar cycles 22 and 23. It is observed that larger numbers of the HSWS events occur during the descending phases, whereas minimum number of HSWS events is observed in the ascending phases of solar activity cycle. High-speed solar wind streams are found to be significantly effective in producing geomagnetic field disturbances. Flare-generated HSWS events are found to be more effective in producing large geomagnetic disturbances in both solar cycles (22 & 23). Frequency of occurrence of HSWS events and sunspot number in the ascending phase of the solar cycles 22 and 23 are positively correlated, while in the maximum, descending and minimum phases of solar cycles (22 and 23) anti-correlation is observed. We find that the plasma electric field (VB) is the most effective parameter for producing.

4 illus, 23 ref

012231   Shi J;Luo M;Huang C (Chemistry and Life Sciences College, Guangxi Teachers Education Univ, Nanning 0530001, China, Email: mfai668@sina.com) : Signal transmission in two-way coupled neural system: system size effect. Indian J Phys 2010, 84(9), 1229-39.

Study the collective dynamical behavior of two-way coupled neural system, which is subject to external noise at the first neuron. It is shown that, for smaller system size, coherence resonance without tuning can occur under certain conditions; for larger system size, a critical value of coupling strength is found, which is a threshold for occurrence of array-enhanced coherence resonance and undamped signal transmission. In particular, when system size is increased, it is more efficient to sustain and amplify the internal signal.

6 illus, 39 ref

012230   Sheikh S A;Koul B L;Lalmani (Physics Dep, National Institute of Technology, Hazaratbal, Srinagar, Kashmir, Email: drlalmani@yahoo.com) : Experimental observations of whistlers and VLF emissions at Srinagar. Ultra Scient phys Sci 2009, 21(3), 541-6.

Different types of whistlers and VLF emissions recorded during day and night times are reported at our newly set-up ground station Srinagar (geomag. lat. 24° 10 N). Dispersion analysis of whistlers recorded during March- June 2009 shows that the dispersion of the whistlers recorded during daytime is higher than those recorded during nighttime. Daytime whistlers are found to appear during very restricted hours in the late afternoon. On the other hand, nighttime whistlers are observed over a wide time interval but generally peak in the early morning, and their dispersion is widely distributed. Further our data analysis shows the occurrence of different types of VLF emissions during day and night times.

2 illus, 11 ref

012229   Saxena N K;Nitendar Kumar;Pourush P K S (Physics Dep, Microwave Lab, Agra College, Agra-282 002, Email: ppourush@yahoo.co.in) : On switiching behavior of ferrrite substrate with magnetostatic and spin wave exchange term. Indian J Phys 2010, 84(9), 1193-1202.

Due to the generation of magnetostatic and spin waves, switching phenomena of ferrite substrate with a normal magnetic biasing field is presented. Generally below the X-band of microwave range, the Pozar's quasi TEM waves (extraordinary waves) were studied, but for the study of X-band there should be an inclusion of spin wave exchange term (ωr) in the magnetostatic wave analysis which depends upon the static internal field (Hex). This term is included in analysis because the wavelength of microwave approach is the inter-atomic distance of ferrite material. In this work we synthesize LiTi ferrite through Solid State Reaction Technique (SSRT) and obtained electric and magnetic properties for the analysis. Absorbing and transmission power coefficients have been calculated to obtain the power loss and transmitted power through the substrate, respectively. The absorbing power coefficient verifies the switching behavior of substrate for certain range of applied external magnetic field (H_o) which depends on the resonance line width parameter (AH) of ferrite material.

4 illus, 1 table, 13 ref

012228   Saxena N K;Nitendar Kumar;Pourush P K S (Physics Dep, Microwave Lab, Agra College, Agra-282 002, Email: nav3091@rediffmail.com) : Theoretical study of circular array of rectangular patches on LiTiMg ferrite substrate at 10 GHz under external magnetic field. Asian J expl Sci 2011, 25(1), 103-8.

Theoretical investigation of 4 elements circular array of microstrip rectangular patches (CAMRP) on LiTiMg ferrite substrate with the effect of magnetic biasing perpendicularly to the substrate at 10 GHz. In this work we synthesized the polycrystalline LiTiMg ferrite of 2200 Gauss 4πM_s and characterize their electric and magnetic properties as a substrate for CAMRP. The important parameters like directivity, radiation power, total impedance, etc. are computed with mathematical software. The total field patterns for array geometry are plotted using vector wave technique and pattern multiplication approach. Results show that applied magnetic field controls the directive beam.

5 illus, 2 tables, 11 ref

012227   Sarmah S;Kumar A (Physics Dep, Tezpur Univ, Tezpur-784 028, Email: ask@tezu.ernet.in) : Optical properties of SnO₂ nanoparticles. Indian J Phys 2010, 84(9), 1211-21.

Considerable research efforts have been focused on the exploration of novel optical properties of nanocrystalline SnO₂ particles such as photoluminescence (PL). In the present work, spherical Sn0₂ nanoparticles are synthesized by solid state reaction at different temperatures using tin chloride dihydrate and sodium hydroxide flakes as precursors. Transmission electron micrograph shows uniform and spherical Sn0₂ nanoparticles of diameter 30-40 nm. Micro-Raman spectra show an inverse relationship of line-width with SnO₂ particle size. The band gap of SnO₂ is calculated by plotting (αh**v)² vs. hv and extrapolating the linear portion of it to a = 0 and found it to be 3.76-4.24 eV. Photoluminescence intensity increases with the increase of solid state reaction temperature up to 873 K. This is attributed to the generation of the oxygen ion vacancies in SnO₂.

8 illus, 1 tables, 35 ref

012226   Sanyal P;Tarat S;Majumdar P (NO, Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad-211 019, Email: prabs@mri.ernet.in) : Order-disorder transitions: structural and magnetic ordering in double perovskites. Indian J Phys 2010, 84(10), 1379-90.

Using an effective lattice gas-like model for B-B' site ordering study order-disorder transitions in double perovskite materials A₂BB'O₆. Motivates this effective model from a microscopic hamiltonian. Using this model, we are able to address several experimentally observed issues including nonmonotonic dependence of the degree of order on annealing temperature, and the rapid decrease of order upon overdoping with either B or B' species. We also study ordering in the 'ternary' compounds A₂BB'_1-y B''_yO₆, using a variant of the Blume-Emery-Griffiths model. Several issues related to structural and magnetic ordering are discussed.

11 illus, 17 ref