009351   Mahalakshmi S;Srinivasa Manja K (Department of Physics, Pondicherry University, Pondicherry-605 014, Email: mahalakshmism@gmail.com) : IR and X-ray studies on nickel ferrite with rare earth doping. Indian J Phys 2006, 80(4), 401-3.

The nickel ferrite of composition Ni_xFe_3-xO₄ with x = 0.3, 0.5, 0.7, 0.9 doped with neodymium and gadolinium were studied by infrared absorption spectroscopy. The IR spectrum showed two main absorption bands v<1 and v₂ in the range of 400cm^-1-600cm^-1 arising from the octahedral and tetrahedral complexes. The positions of absorption bands are compositional dependent whose dependence could be attributed to the variation in cation - oxygen bond distances. The force constant of tetrahedral and octahedral sites supports cation distribution. With the addition of gadolinium the absorption bands v₁ and v₂ were found to be broadened and the peaks are diffused. The lattice constants were found to decrease with the addition neodymium and gadolinium.

1 illus, 1 table, 14 ref

009350   Kushwaha A K;Kushwaha S S (Department of Physics, Bundelkhand University, Jhansi-284 128, Email: akkphys_bu@yahoo.com) : Phonons behavior in ternary chalcogenide mixed spinel. Indian J Phys 2006, 80(4), 397-9.

In recent years, various studies of electrical, magnetic and vibrational properties of mixed spinels have been reported which are interesting both practically and theoretically. In the present note we have developed a theoretical model and interpreted the concentration-dependence of lattice vibration frequencies of CDCr₂Se_{401-x and Zn1-xHgxCr2Se4. Finds an overall good agreement between theoretical and experimental data.}

2 illus, 2 tables, 11 ref

009349   Kar A;Bose C (Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata-700 032, Email: juetce_01543@hotmail.com) : Ground state energy in a spherical GaAs-(Al, Ga) As quantum dot with parabolic confinement. Indian J Phys 2006, 80(4), 357-60.

An attempt is made to derive the grournd state energy of a spherical dot having finite quantum well with parabolic potential. The derived result is computed as a function of the size of GaAs-Al_xGa_1-xAs spherical quantum dot, for different barrier heights of the potential well. The ground level in a parabolic dot is found to lie much higher than that in a similar dot with square-well potential.

2 illus, 9 ref

009348   Joseph D;Saxena A;Kailas S;Kaimal R R;Kadam A;Kumar S V;Reddy G L N (Division on Nuclear Physics, BARC, Trombay, Mumbai-400 085, Email: djoseph@magnum.barc.ernet.in) : Chemical effects in Ag and Cr compounds studied by EDXRF, WDXRF and PIXE. Indian J Phys 2006, 80(4), 341-5.

K X-ray intensity ratios of Ag and its compounds such as Agl, AgBr, AgCl, Ag₂SO₄, AgNO₃ and AgCO₃, and Cr and its compounds such as Cr₂O₃, K₂Cr₂O₇, K₂CrO₄, CrSO₄ and CrCl₃ were measured using 59.56 keV γ-rays emitted from ²⁴¹Am 'radioisotope source (EDXRF), X-ray photons from Rh X-ray tube (WDXRF) and protons from the 6MV FOTIA accelerator (PIXE) of energy 2.5 MeV and 5 MeV. The measured ratios in pure metal were compared with Scofield theoretical values. The ratio for K X-ray emission rates by photon excitation, X-ray and proton excitation showed variation for the compounds from the pure elements and for different modes of excitation.

6 illus, 2 tables, 21 ref

009347   Ghosal A;Chattopadhyay D (Institute of Radio Physics and Electronics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata-700 009, Email: aghosal16@yahoo.com) : Diffusion thermopower in CdSe single quantum wells. Indian J Phys 2006, 80(4), 405-7.

Diffusion thermopower (S_d) of the two-dimensional (2D) electron gas in CdSe single quantum wells is calculated in the temperature range 1.4K-12K in the framework of Fermi-Dirac statistics incorporating carrier scattering through acoustic phonons via deformation-potential and piezoelectric couplings, and through background and remote ionized impurities. The quantity -S_d is found to increase with temperature and the 2D electron concentration, and is mainly limited by ionized impurity scattering. The dependence of S_d on the well width and the ionized impurity concentration is found to be insignificant.

2 illus, 9 ref

009346   Ganguly N D;Lyer K N (Department of Physics, St. Xavier's College, Ahmedabad-380 009) : Impacts of the 20<. Indian J Phys 2006, 80(4), 335-9.

The ozone data obtained from Nimbus-7 and Earth probe Total Ozone Mapping Spectrometer (TOMS) has been used to study the impact of coronal mass ejection (CME) on the columnar ozone concentration in India. A comparison of columnar ozone values for different solar proton events (SPE) observed at Srinagar indicates that although the 20th Jan., 2005 SPE was the most intense in the last 15 years, the ozone depletion was found to be maximum in the 23th March, 1991 event followed by 20th Jan., 2005, 4th Nov., 2001, 19th Oct., 1989 and 28th Oct., 2003 events. A comparison between the ozone levels observed in different Indian cities for a few days after the 20th Jan., 2005 SPE indicates that the ozone values were found to decrease sharply at higher latitudes compared to places located in the tropics. The ozone values measured by TOMS. Dobson Spectrometer and AURA Ozone Monitoring Instrument (OMI) were found to decrease for a short period from 20th January to 25th January after which the ozone levels started recovering to normal values. The vertical ozone profiles obtained from Microwave Limb Sounder for New Delhi, indicate that the ozone-mixing ratio in the 3.0 to 10.0 hPa pressure range decreased consistently from 21st Jan., 2005 to 25th Jan., 2005 and thereafter, recovered by the 31st January, 2005.

5 illus, 9 ref

009345   Farag E S M (Department of Basic Science of Engineering, Faculty of Engineering,, Shebin El-Kom, Minufiya University, Egypt, Email: awsymkh@yahoo.com) : Electrical properties and the crystallization kinetics of amorphous a-Ge_30-xSb_xS₇₀ films. Indian J Phys 2006, 80(4), 367-71.

Amorphous Ge_30-xSb_xS₇₀ films have been prepared by thermal evaporation technique and electrical conductivity has been measured in the temperature range of 300-400K. The temperature dependence of the electrical conductivity for all compositions has been recorded and discussed. The change in the electrical conductivity with time was also recorded at different temperatures during the amorphous-crystalline transition. The kinetic parameters determined have made it possible to discuss the growth of the crystals in two or three dimensions.

6 illus, 3 tables, 22 ref

009344   Chakrabarti S;Pradhan A;Bandyopadhyay A;Ray A;Ray B;Bhattacharya D;Ghosh P N (Department of Physics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata-700 009) : Velocity selective resonances and electromagnetically induced transparency in atomic rubidium. Indian J Phys 2006, 80(5), 487-9.

Using the same experimental setup, two different configurations of the pump and probe laser fields are studied in this work. When the pump and probe laser fields together produce a Λ system. Gets a centrally located dip due to Electromagnetically Induced Transparency. However, when the pump and probe laser fields produce a V-system we observe Velocity Selective Resonance Dips.

6 illus, 4 ref

009343   Bhar G C;Chatterjee U (Department of Physics, Laser Laboratory, Burdwan University, Burdwan-713 104, Email: dgp_buphygcb@sanchernet.in) : Development of ultraviolet laser for disinfection of potable water. Indian J Phys 2006, 80(5), 517-21.

The ultraviolet (UV) radiation is an effective means against bacteria and protozoan pathogens for disinfection of drinking water killing micro-organisms by causing irrepairable damage to their DNA. Some protozoan cysts like giardia require a high doze of UV intensity of 16000 μW.s/cm² for total destruction. Low level of UV radiation as that available from commercial source for insecticides and viriside is incapable of elimination of such resistive cysts. So UV radiation is of demand for this. But except excimer lasers that are of limited life and hard to operate, there is practically no UV laser as such. The easy way is to generate through nonlinear frequency mixing of laser radiations from Nd : YAG and Dye lasers in a suitable nonlinear crystal. Except borates few nonlinear crystals can be used in the UV region down to 200 nm or below. The borate group includes BBO, LBO, CLBO, LB₄ etc. while the most recent addition is KABO. Although the generation of UV radiation of 240-280 nm that is important for DNA absorption is of no problem, but tuning below 200 nm is not quite easy. The shortest wavelength generated is 187.9 nm in BBO through sumfrequency mixing. Shows that it can be tuned to still lower wavelength if impurity-free BBO is used and the crystal be cooled. Crystal LB₄ is better in this respect as it transmits down to 170 nm. But since nonlinearity of LB₄ is very low, available intensity of UV radiation may not be sufficient for such disinfecting applications. So some ingenious technique of multipass has been proposed and demonstrated to realize high conversion in such crystals.

3 illus, 1 table, 7 ref

009342   Baldev Raj;Tata B V R (Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Resear, , Kalpakkam-603 102) : Confocal laser scanning microscopy and laser light scattering: applications in soft matter and technological materials. Indian J Phys 2006, 80(5), 471-86.

The availability of laser light sources and powerful low-cost computer data processing and imaging systems have helped in popularizing the confocal laser scanning microscope (CLSM) in the field of materials science and technology and in life sciences. CLSM has great advantage over a conventional microscope because it rejects light that does not come from the focal plane, enabling one to perform optical slicing and construction of three-dimensional (3D) images. Because of this unique feature, CLSM is now finding wider applications in the study of a variety of materials and process such as crystallization and glass transition in colloidal systems, phase separation in polymer blends, fracture toughness in alloys and microvisualization of corrosion. This paper reviews some of these recent applications and also discusses our results in providing evidence for long-range attraction between like-charged particles and for the occurrence of gas-solid transition in highly charged colloidal systems. Apart from colloids, other macromolecular systems (e.g. gels, surfactant systems, membranes etc.) that constitute soft matter are characterized by building blocks with typical length scales that range between tens of nanometers to micrometers. The increased dimension of these basic building blocks essentially causes the materials to be soft (i.e. elastic constants of the order of 10-100 dynes/cm²) and dynamics to be very slow (- microseconds to several seconds). The information with regard to the structure and dynamits at the lower end of length and time scales in the soft matter can be obtained using laser light scattering (photon correlation spectroscopy) and that at the higher end using CLSM. By combining judiciously the two techniques, investigates charged colloidal systems for their structure, dynamics and phase behavior and these results are discussed in this paper.

13 illus, 47 ref

009341   Acharya A (Department of Physics, University College of Engineering, Burla-768 018, Email: anjana@iopb.res.in) : Complex shape parameter for s-wave scattering from zero-energy wave functions. Indian J Phys 2006, 80(4), 409-11.

Using an extension of the method of Kermode and Van Dijk [Phys. Rev. C42 1891 (1990)] we show how a complex shape parameter for complex local potential can be determined in terms of zero-energy wave functions for s-wave scattering.

1 illus, 7 ref

008276   Wenhong T;Yin W;Xinghua FU;Qihong W (Materials Science and Engineering Dep, Jinan University, Jinan 250022, PR China, Email: mse_fuxh@ujn.edu.cn) : Influence of bismuth on properties and microstructures of Sr_0.5Ba_0.5-xBi_xTiO₃ thin films. Bull Mater Sci 2006, 29(5), 523-7.

The influence of bismuth (Bi) on the dielectric and ferroelectric properties of Sr_0.5Ba_0.5-xBi_xTiO₃ (BST, 0 ≤x≤ 0.030 mol) thin films was studied. The results showed that the dielectric constant (ε_x) and dielectric loss (tan δ) decreased, and temperature, T_m, for maximum and δ_r (Curie temperature), moved to lower temperature with increasing Bi content. The P_r, P_s and E_c were 0.22μC/cm², 0.32μC/cm² and 60 kV/cm, respectively for Sr_0.5Ba_0.485Bi_0.015TiO₃ thin films measured at 100 Hz, 20 V. The microstructure of BST thin films was studied by XRD and TEM. Tetragonal perovskite grains existed in BST thin films, but the grain size decreased with increasing doping ratio in BST. The characteristic absorption band for octahedron [TiO₂] (471.65 cm^-1) was shifted to lower wave number.

8 illus, 6 ref

008275   Tennakone K (NO, Institute of Fundamental Studies, Hantana, Kandy, Sri Lanka, Email: tenna@ifs.ac.lk) : Ball lightning: elusive behaviour depending upon proton conductivity. Curr Sci 2006, 90(9), 1247-50.

Ball lightning is pictured as a negatively charged spherical bubble with a shell of oriented dipolar water molecules. The bubble is balanced by outward electrostatic stress and inward forces of atmospheric pressure and or surface tension forces. Because of the low electronic conductivity of condensed water, electrons slowly leak away from the surface in the radial direction, forming a corona. The charge on the ball decays exponentially with a characteristic mean life time depending on the electronic conductivity of the shell. Protons confined in the shell induce an electric conductivity to the shell in the tangential direction. When the bubble is deformed by an inductive field, mobility of the protons develops a higher charge density in the more curved regions of the shell. Differential electrostatic stress generates a feedback propelling force enabling it to bounce off from surfaces or penetrate through holes.

4 illus, 25 ref

008274   Surender V;Arundhathi N;Kishan Rao K (Physics Dep, Kakatiya University, Warangal-506 009, Email: kishankotte@yahoo.co.in) : Growth mechanism of NaClO₃ and NaBrO₃ crystals from aqueous solutions. Bull Mater Sci 2006, 29(5), 427-32.

Study of growth rates of NaClO₃ and NaBrO₃ has been carried out using a small growth cell by in situ observation. Normal growth rates of {100} faces of NaClO₃ and {111} faces of NaBrO₃ along {110} direction are measured under relatively high supersaturation ranging from 3-8%. In the initial stages of growth, {100}, {110} and {111} faces develop in NaClO₃ and gradually all the faces are replaced by the {100} faces only. In the case of NaBrO₃, mostly {111} faces develop with occasional occurrence of small {100} faces at the intersection of {111} faces. The growth mechanisms are investigated from growth rate vs supersaturation plots and from the observations of surface features. In the saturation range, the growth mechanism appears to be due to two-dimensional growth mechanisn.

5 illus, 18 ref

008273   Srivastava S K (NO, Centre for Advanced Technology, Jagadhri, Yamunanagar, Haryana-135 003, Email: sanjeevsrivastava1980@rediffmail.com) : Analysis of thermal expansivity of NaCl and KCl crystals at high temperatures. Indian J Phys 2006, 80(6), 655-8.

Various relationships for temperature dependence of thermal expansivity in high temperature domain at I bar pressure are deduced for NaCl and KCl crystals. These relationships are derived on the basis of temperature dependence of volume expansion ratio studied recently. It is found that among the various relationships, the thermal expansivity derived from the Srivastava equation of volume expansion ratio shows close agreement with the experimental data available in literature. The present relationship for thermal expansivity may be used to understand the high temperature behaviour of solids.

4 illus, 19 ref

008272   Samanta L K;Chatterjee S;Chandra P (Physics Dep, Burdwan University, Burdwan-713 104, West Bengal, Email: vebu@satyam.net.in) : On the acoustic deformation potentials of some II-IV-V₂ ternary chalcopyrites and their mixed versions. Indian J Phys 2006, 80(6), 651-4.

The valence band and conduction band acoustic deformation potentials of some II-IV-V₂ chalcopyrites and their mixed versions have been evaluated for the first time from the knowledge of the temperature dependence of the band gap dE_g/dT and the pressure dependence of the band gap dE_g/dp. It is interesting to note that the analysis gives an idea of electron-phonon contribution term to the temperature dependence of the band gap in these compounds which is very useful for understanding some physical processes taking place in these type of compounds.

2 tables, 32 ref

008271   Rao S (NO, Harish-Chandra Research Institute, Chhatnag Road, Jhusi, Allahabad-211 019, Email: sumathi@mri.ernet.in) : Nonlinear sigma model approach to quantum spin chains. Indian J Phys 2006, 80(6), 599-607.

Introduces and motivate the study of quantum spin chains on a one-dimensional lattice. Classifies the varieties of methods that have been used to study these models into three categories, (a) exact methods to study specific models (b) field theories to describe fluctuations about the classical ordered phases and (c) numerical methods. Discusses the J₁-J₂-δ model in some detail and end with a few comments on open problems.

3 illus, 21 ref

008270   Rao K J;Pecquenard B;Gies A;Levasseur A; Etourneau J (Solid State and Structural Chemistry, Indian Institute of Science, Bangalore-560 012, Email: kjrao@sscu.iisc.ernet.in) : Structural and electrochemical behaviour of sputtered vanadium oxide films: oxygen non-stoichiometry and lithium ion sequestration. Bull Mater Sci 2006, 29(5), 535-46.

Structural and electrochemical aspects of vanadium oxide films recently reported from ICMCB/ENSCPB have been examined using appropriate structural models. It is shown that amorphous films are non-stoichiometric as a result of pre-deposition decomposition of V₂O₅. It is proposed that the structure of amorphous films corresponds to a nanotextured mosaic of V₂O₅ and V₂O₄ regions. Lithium intercalation into these regions is considered to occur sequentially and determined by differences in group electronegativities. Open circuit voltages (OCV) have been calculated for various stoichiometric levels of lithiation using available thermodynamic data with approximate corrections. Sequestration of lithium observed in experiments is shown to be an interfacial phenomenon. X-ray photoelectron spectroscopic observation of the formation of V³⁺ even when V⁵⁺ has not been completely reduced to V⁴⁺ is shown to be entirely consistent with the proposed structural model and a consequence of initial oxygen nonstoichiometry. Based on the structural data available on V₂O₅ and its lithiated products, it is argued that the geometry of VO_n polyhedron changes from square pyramid to trigonal bipyramid to octahedron with increase of lithiation. A molecular orbital based energy band diagram is presented which suggests that lithiated vanadium oxides, Li_xV₂O₅, become metallic for high values of x.

3 illus, 6 tables, 28 ref

008269   Parashar J (Applied Physics Dep, Samrat Ashok Technological Institute, Vidisha-464 001, Madhya Pradesh, Email: jparashar@hotmail.com) : Third harmonicgeneration by an obliquely incident laser on a vacuum - plasma interface. Indian J Phys 2006, 80(6), 647-50.

A high power laser obliquely incident on a plasma produces a third harmonic component in the reflected component. The process is sensitive to the plasma frequency and the angle of incidence. At higher plasma densities, the efficiency peaks at smaller angles of incidence and as the plasma becomes rarer, the efficiency peaks at higher angles of incidence. The efficiency also drops with plasma frequency. In gaseous plasma, the efficiency is higher by more than an order as compared with solid-state plasmas.

3 illus, 9 ref

008268   Mallick B;Patel T;Behera R C (NO, Institute of Physics, Sachivalay Marg, Bhubaneswar-751 005, Email: bmallick@iopb.res.in) : Effect of neutron irradiation on the 1615-cm<. Indian J Phys 2006, 80(6), 621-4.

Amorphous polyethylene terephthalate (PET) fibres of denier per filament value 2.17 were irradiated by fast neutron of energy 4.44 MeV at different fluences. The radiation-induced physical, macromolecular changes have been investigated applying micro-Raman scattering. It is observed that the 1615-cm^-1 band of amorphous PET fibre get vanished at the fluence of 1x10¹¹ n/cm² indicating the formation of pure gauche phase due to radiation heating. This gauche phase was also confirmed from the entropy value of irradiated PET material obtained using DSC technique. A phase-diagram of amorphous PET was plotted using Raman band intensity and neutron fluence.

2 illus, 20 ref

008267   Kurkcuoglu M E;Aytekin H (NO, Zonguldak Karaelmas University, Vocational School, Zonguldak, 67100, Turkey, Email: huseyinaytekin@gmail.com) : Investigation of the <. Indian J Phys 2006, 80(6), 641-5.

The experimental data on elastic scattering of ¹⁶O+¹⁶O reaction for ten incident energies between E_lab=75.0 and 145.0 MeV have been analyzed theoretically within the framework of the Optical model formalism. In the construction of the real part of the optical potential, the phenomenological Woods-Saxon squared and calculated double-folding model potential forms have been used with new parameters. The analyses using those potential forms have been compared with the experimental data. The most suitable fits have been obtained when phenomenological Woods-Saxon squared potential forms are used in both real and imaginary parts of the nuclear potential. Our cross section analyses have exhibited a very good agreement with the experimental measurements, and agreement with the experimental data is better than the previous theoretical works. Thus, the ¹⁶O+¹⁶O system has been described by optical potentials having a deep real potential part and a weak absorptive imaginary potential part.

1 illus, 1 table, 32 ref

008266   Jagannathan V (Reactor Physics Design Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: vjagan@magnum.barc.ernet.in) : Economics of nuclear power generation. Curr Sci 2006, 90(12), 1591-3.

^ssc2 ref

008265   Islam J N;Islam M R (NO, Research Centre for Mathematical and Physical Sciences, Chittagong Uni, Chittagong-4331, Bangladesh, Email: mrafiqulislam_cu@yahoo.com) : Exact solution of the time-dependent Ginzburg-Landau equations for Propagating fronts in superconductor. Indian J Phys 2006, 80(6), 637-40.

Finds an exact solution of the time dependent Ginzburg-Landau (TDGL) equations in connection with the problem of front (interface) propagation in superconductor. Finds a distinct solution of the mentioned problem found earlier by Di Bartolo and Dorsey with a front speed c = 2828 and display some of its properties.

2 illus, 9 ref

008264   Herndon J M (Transdyne Corporation, , 11044 Red Rock Drive, San Diego, CA 92131, USA, Email: mherndon@san.rr.com) : Energy for geodynamics: mantle decompression thermal-tsunami. Curr Sci 2006, 90(12), 1605-6.

^ssc15 ref

008263   Gursharan Singh et al (Bhabha Atomic Research Centre, , Trombay, Mumbai-400 085) : Automated gamma scanning system for on-line inspection of industrial process columns. BARC Newsl 2006, (NULL), 2-7.

7 illus, 5 ref

008262   Ghosh D K (NO, Indian Institute of Technology, Bombay, Powai, Mumbai-400 076, Email: dkg@iitb.ac.in) : M-G hamiltonian - a pedagogic review. Indian J Phys 2006, 80(6), 577-81.

Discusses Majumdar-Ghosh Hamiltonian which is a one dimensional system of spin 1/2 particles with isotropic interactions between nearest and next-nearest neighbours. The model is exactly solvable when the next-nearest neighbour strength is half that between the nearest neighbours. The ground state is doubly degenerate and consists of dimers of nearest neighbour singlet pairs.

3 illus, 16 ref

008261   Ganguly P (Physical Chemistry Division National Chemical Laboratory, , Pune-411 008, Email: patch_ganguly@rediffmail.com) : Molecular geometry from molecular tensegrity: A case study of gas-phase MX₂ compounds. Curr Sci 2006, 90(9), 1251-3.

Defined tensegrity factor, t^±₀₀, for X-M-X linkages of gas-phase MX_n compounds (X is an atom of an insulating element) that is a measure of the matching of `ideal' 1,2-(single-bonded) M-X distance, d <sub>MX</sub><sup>00</sup> to the `ideal' (non-bonded) 1,3-X_X distances, d_MX⁰⁰. The actually observed 1,3-distance, d_xx is given (within 1% error) by 2CR(X)/Fs, where Fs (= 2-1.41^±₀₀) is shown to be an ab initio quantity with no adjustable parameter, no dependence on actual M-X distance or bond order and with 2CR(X) depending only on whether M is an atom of an insulating element (2CR(X) = d_xx⁰⁰) or whether M is metallic (2CR(X) = 1.1d_xx⁰⁰). This is illustrated for gas-phase MX₂ compounds.

2 illus, 9 ref

008260   Ganesan S;Srivenkatesan R;Murthy C S R C; Dhekne P S (Bhabha Atomic Research Centre, , Trombay, Mumbai-400 085) : A regional IAEA-NDS nuclear data mirror site in India for the Asian region. BARC Newsl 2006, (NULL), 9-21.

6 illus, 8 ref

008259   Gadkari A B;Zope Z K (Physics Dep, G.K.G. College, Kolhapur-416 012, Email: kashokabg@yahoo.com) : Electrical conductivity measurement in a Se-Te-In system. Bull Mater Sci 2006, 29(5), 461-6.

The I-V characteristics and d.c. conductivity measurements of Se₇₀Te_30-xIn_x, where x = 0,1,3,5,7, 9% atomic weight, have been experimentally investigated. The increase in room temperature conductivity is attributed to increase in the percentage of indium (In), which creates charged centres inside the bulk of the material. The decrease in activation energy with increase in indium content has been discussed on the basis of formation of new charged centres, In^-₄(C⁰₂)₃ in the mobility gap which shifts the Fermi level towards the valence band. An energy band diagram has been suggested on the basis of new charged centres, In^-₄(C⁰₂)₃ and C⁺₃, for Se-Te-In system.

6 illus, 1 table, 32 ref

008258   Das S;Biswas B B (Bhabha Atomic Research Centre, , Trombay, Mumbai-400 085) : Fault-tolerant power supply for safety significant nuclear instrumentation and control. BARC Newsl 2006, (NULL), 8-17.

8 illus, 10 ref

008257   Dalal P V;Saraf K B (PG Department of Physics, Pratap College, Amalner-425 401) : Growth and study of barium oxalate single crystals in agar gel. Bull Mater Sci 2006, 29(5), 421-5.

Barium oxalate was grown in agar gel at ambient temperature. The effect of various parameters like gel concentration, gel setting time and concentration of the reactants on the growth of these crystals was studied. Prismatic platy shaped spherulites and dendrites were obtained. The grown crystals were characterized by X-ray powder diffractometry, infrared spectroscopy, thermogravimetric and differential thermal analysis. An attempt is made to explain the spherulitic growth mechanism.

8 illus, 2 tables, 21 ref

008256   Chowdhury A;Kumar J (Materials Science Programme, Indian Institute of Technology, Kanpur-208 016, Email: preac@leeds.ac.uk) : Morphology, surface topography and optical studies on electron beam evaporated MgO thin films. Bull Mater Sci 2006, 29(5), 513-21.

Electron beam evaporated thin films of MgO powder synthesized by burning of magnesium ribbon in air and sol-gel technique are studied for their microstructure (SEM), surface topography (AFM), and optical transmission behaviour (UV-visible spectroscopy). MgO thin films are shown to be either continuous or have mesh like morphology. The bar regions are believed to be of magnesium hydroxide formed due to absorption of moisture. Their AFM images exhibit columnar/pyramidaVtruncated cone structure, providing support to the 3D Stranski-Krastanov model for film growth. Further, they are shown to have high transmittance (<126>90%) in the wavelength range 400-600 nm, but absorb radiation below 350 om substantially giving signature of a band transition.

7 illus, 3 tables, 17 ref

008255   Choudhury D K;Gogoi R (Physics Dep, Gauhati University, Guwahati-781 014, Assam, Email: dkc_phys@yahoo.co.in) : Some comments on fractality of proton at small x. Indian J Phys 2006, 80(6), 659-62.

Using the concept of self-similarity in the structure of the proton at small x, comments possibility of a single positive fractal dimension of proton in analogy with classical monofractals. Plausible dynamics and physical interpretation of fractal dimension are also discussed.

2 illus, 1 table, 23 ref

008254   Chatterji T (NO, Instutut Laue-Langevia, BP 156, 38042 Grenobie Cedex 9, France, Email: chatt@ill.fr) : Orbital ice and its melting phenomenon. J Phys 2006, 80(6), 665-75.

Coins a phrase "orbital ice" to describe the orbitally ordered phase of LaMnO₃ which is formed by the cooperative Jahn-Teller transition below T_n = 750 K. We interpret the transition at T_n to be a "melting" of the "orbital ice" by analogy with the phenomenon of ice melting. We will demonstrate some similarities between the two melting phenomena of which the first phenomenon is of electronic origin and the other of course is a well known lattice melting known to humanity for hundreds of centuries.

17 illus, 6 ref

008253   Chakraborty A (NO, , AD-369, Salt Lake City, Kolkata-700 064, Email: tpasg@mahendra.iacs.res.in) : Effect of high magnetic field on the scattering of electron with atomic hydrogen. Indian J Phys 2006, 80(6), 615-19.

Investigation has been carried out to show the effect of high magnetic field over the scattering parameters for electron-hydrogen scattering. The magnitudes of the magnetic field vary from 0.2 to 5 a.u. Three first-order models have been employed to study the system. These models reveal the relative effect of high magnetic field on the projectile and the target both separately and simultaneously. The scattering cross sections are compared amongst themselves and also with the corresponding field-free results. It has been found that the effect of field distortion of the target is negligible on the scattering parameters. But the dressing of the incoming electron for the magnetic field bring significant qualitative change.

5 illus, 14 ref

008252   Chakrabarti B K;Inoue J (NO, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700 064, Email: bikask.chakrabarti@saha.ac.in) : Solvable quantum antiferromagnet model. Indian J Phys 2006, 80(6), 609-12.

Introduces a quantum antiferromagnet model, having exactly soluble thermodynamic properties. It is an infinite range antiferromagnetic Ising model put in a transverse field. The free energy gives the ground state energy in the zero temperature limit and it also gives the low temperature behaviour of the specific heat, the exponential variation of which gives the precise gap magnitude in the excitation spectrum of the system. The detailed behaviour of the (random sub lattice) staggered magnetisation and susceptibilities are obtained and studied near the Neel temperature and the zero temperature quantum critical point.

2 illus, 10 ref

008251   Bose I (Physics Dep, Bose Institute, 93/1, A.P.C. Road, Kolkata-700 009, Email: indrani@bosemain.boseinst.ac.in) : Majumdar-Ghosh-like spin models in low dimensions. Indian J Phys 2006, 80(6), 593-7.

The Majumdar-Ghosh model occupies a special position amongst the models of interacting spin systems. The model has motivated the search for other low-dimensional spin systems with quantum paramagnetic ground states and a gap, the so-called spin gap, in the excitation spectrum. In this brief review, some generic features of MG-like spin models will be described in terms of theoretical results and experimentally observed phenomena.

32 ref

008250   Bhuvana;Kulkarni G U (Chemistry and Physics of Materials Unit and DST Unit on Nanoscience, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur PO, Bangalore-560 064, Email: kulkarni@jncasr.ac.in) : Optimising growth conditions for electroless deposition of Au films on Si(111) substrates. Bull Mater Sci 2006, 29(5), 505-11.

Electroless deposition of Au films on Si(111) substrates from Duorinated-aurate plating solutions has been carried out at varying concentrations, deposition durations as well as bath temperatures, and the resulting films were characterized by X-ray diffraction, optical profilometry, atomic force microscopy and scanning electron microscopy. Depositions carried out with dilute plating solutions (<62> 0.1 mM) at 28°C for 30 min produce epitaxial films exhibiting a prominent Au(111) peak in the diffraction patterns, while higher concentrations or temperatures, or longer durations yield polycrystalline films. In both epitaxial and polycrystalline growth regimes, the film thickness increases linearly with time, however, in the latter case, at a rate an order of magnitude higher. Interestingly, the surface roughness measured using atomic force microscopy shows a similar trend. On subjecting to annealing at 250°C, the roughness of the film decreases gradually. Addition of poly (vinylpyrrolidone) to the plating solution is shown to produce a X-ray amorphous film with nanoparticulates capped with the polymer as evidenced by the core-level photoelectron spectrum. Nanoindentation using AFM has shown the hardness of the films to be much higher (<126>2-19 GPa) than the bulk value.

5 illus, 1 table, 33 ref

008249   Baskaran G (NO, Institute of Mathematical Sciences, Chennai-600 113, Email: baskaran@imsc.res.in) : Resonating valence bond states in 2 and 3D - brief history and recent examples. Indian J Phys 2006, 80(6), 583-92.

Resonating valence bond states are quantum spin liquids, having low energy spin- 1/2 (spinon) or spin-1 excitations. Although spins are 'disordered', they possess subtle topological orders and some times chiral orders. RVB states are easily appreciated and seem natural in the quantum fluctuation dominated ID world. In 2 and 3D, competing orders such as antiferromagnetism, charge order or even superconductivity often hide an underlying robust quantum spin liquid state. Introduction of additional spin interactions or doping of delocalized charges, or finite temperatures, could frustrate the long range magnetic order and reveal a robust RVB state. To this extent they are natural in 2D and above. Presents a brief history of insulating RVB states. Gives summery of recent theory of RVB states for 2 and 3D systems, including some newly synthesised ones: (i) boron doped diamond, (ii) Na_xCoO₂:yH₂O , (iii) quasi 2D organic conductors and (iv) a 2D graphene sheet.

11 illus, 95 ref

008248   Bari R H;Patil L A;Patil P P (P.G. Department of Physics, Pratap College, Amalner-425 401, Email: lapresearch@rediffmail.com) : Structural, optical and electrical properties of chemically deposited nonstoichiometric copper indium diselenide films. Bull Mater Sci 2006, 29(5), 529-34.

Thin films of copper indium diselenide (CIS) were prepared by chemical bath deposition technique onto glass substrate at temperature, 60°C. The studies on composition, morphology, optical absorption, electrical conductivity and structure of the films were carried out and discussed. Characterization included X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray analysis (EDAX) and absorption spectroscopy.

6 illus, 3 tables, 27 ref

008247   Abdelkhaled M M (Nuclear Physics Dep, Nuclear Research Centre, Atomic Energy Authority, Inshas, P.O. Box-13759, Cairo, Egypt, Email: Mohamed_moustafa_2000@yahoo.com) : Unsteady MHD convection and mass transfer flow of micropolar fluids past a vertical permeable moving plate with heat absorption. Indian J Phys 2006, 80(6), 625-35.

By the use of the theory of micropolar fluids due to Eringen, perturbation method is presented to study an unsteady MHD convection and mass transfer flow of micropolar fluids past a vertical permeable moving plate with heat absorption. The plate moves with a constant velocity in the direction of fluid flow, while the free stream velocity follows an exponentially increasing or decreasing small perturbation law. Approximate solutions of the coupled nonlinear governing equations are obtained for different values of microrotation and magnetic parameters. Numerical calculations are carried out for the various parameters entering into the problem. The results of velocity, angular velocity, temperature and concentration profiles have been presented graphically for various values of the material parameters. The results indicate that the micropolar fluids display a reduction in drag as well as heat transfer rate when compared with Newtonian fluids.

29 illus, 20 ref

007263   Vaid B H;Gnanaseelan C;Thompson B;De A; Salvekar P S (Indian Inst of Trop Meteorology, , Dr. Homi Bhabha Road, Pashan, Pune-411 008, Email: seelan@tropmet.res.in) : Heat storage variability in the Indian Ocean using topex/poseidon altimeter data. J Indian Geophys Union 2006, 10(2), 101-17.

Sea surface height anomalies (SSHA) derived from the Topex/Poseidon (T/P) satellite are used for computing heat storage anomalies (HSA) and heat storage rates (HSR) over the north Indian Ocean [20°S - 25°N and 35°E - 115°E] for a period of 10 years (1993-2002). In normal years during September to November positive HSA and HSR were observed in the region 10°S - Equator, 90°E -110°E. But during the years 1994 and 1997 negative HSA and HSR were observed in this region, this interannual variability has recently been addressed as Indian Ocean Dipole (IOD). The heat content anomaly clearly showed the existence of the dipole like structure in the equatorial Indian Ocean (IO) in 1994 and 1997. The T/P measurement showed large SSHA in the western equatorial Indian Ocean during 1994-1995 and 1997-1998 IOD events that represent the oceanic response to the surface wind forcing. These anomalies in turn played an important role in forming the sea surface temperature anomalies (SSTA). The 1997 Dipole mode structure was observed to be stronger than 1994 and that can be clearly seen in calculated HSA, HSR, T/P SSH anomalies, thermocline depth (D20) anomaly derived from Simple Ocean Data Assimilation (SODA) and in HADISST anomaly. The Rossby wave propagation is found to have a good correlation with the heat content anomaly derived from Topex/Poseidon sea surface height anomalies. During the dipole years 1994-95 and 1997-98 the anomalous westward propagation of SSHA and HSA were clearly observed especially in the region south of 7°S and strengthened in 80 - 90°E belt. Wind stress curl anomalies play an important role in strengthening this propagation in 80-90°E and hence warming the west Indian Ocean in the early months of 1998. It was seen that positive and negative dipole years are inversely correlated in the southeastern equatorial Indian Ocean (10°S - Equator, 90°E-110°E). To understand the interannual variability of upper ocean SSHA, Complex Empirical Orthogonal Function (CEOF) has been applied to T/P SSHA and HSA. IOD has been shown to be the leading mode of the interannual variability of the upper ocean SSHA and HSA. The westward propagation of the phase is in agreement with the sea saw thermocline variability observed in the equatorial Indian ocean.

11 illus, 42 ref

007262   Sidharth B G (B.M.Birla Sci Cent, , Adarsh Nagar, Hyderabad-500 063) : The fuzzy space-time universe. Int J Syst Cybernetics Inf 2006, (Jan), 43-7.

42 ref

007261   Sastry R G;Jose M K (Dep of Earth Sci, IIT, Roorkee-247 667, Email: rgss1fes@iitr.ernet.in) : A semi-analytical procedure for the computation of hydraulic heads and streamlines in multi-layered aquifer systems. J Indian Geophys Union 2006, 10(2), 131-40.

Analytical solutions are presented for the computation of steady-state hydraulic heads and streamlines in multi-layered aquifer systems. Considering the analogy between direct-current electrical flow and groundwater flow, the proposed methodology, point source over n-layer (NLPNT) invokes the geoelectric sounding principles. Numerical examples for the cases of a 3, 4, and 5-layered aquifer system are presented. Comparison of NLPNT solutions with the corresponding solutions obtained from popular MODFLOW indicate that the NLPNT is quite cost-effective in computing hydraulic heads and streamlines.

8 illus, 16 ref

007260   Rastogi R G (Phys Res Lab, , Ahmedabad-380 009, Email: profrgrastogi@yahoo.com) : Declination effects on magnetospheric ring current over the magnetic equator. J Indian Geophys Union 2006, 10(2), 63-8.

It has been shown that the magnetospheric ring current has a very significant effect on the storm time variations of the Eastward component (Y) besides the horizontal component (H) at ground magnetic observatories. The storm time variation of H is a depression at low and middle latitude at any of the longitudes, roughly following the variations of Dst index. The storm time variation of the Y at equatorial electrojet region shows a large depression in East Brazil longitudes and a large increase in East African longitudes, and only small changes in the Pacific longitudes. These changes are shown to be related to the index sin^-1 (ψ - D) where ψ and D are the dipole and dip declination at the stations. At equatorial stations the ionospheric Sq current flows along the dip equator while the disturbance ring current flows along the dipole equator.

5 illus, 2 tables, 12 ref

007259   Murty T S;Rao A D;Nirupama N;Nistor I (Dep of Civ Engng, Univ of Ottawa, Ottawa, Canada, Email: smurty@hotmail.com) : Tsunami warning systems for the hyperbolic (Pacific) parabolic (Atlantic) and elliptic (Indian) oceans. J Indian Geophys Union 2006, 10(2), 69-78.

It is shown that the Pacific, Atlantic and Indian Oceans have very different tsunami characteristics. Hence the numerical modelling of tsunamis in these three oceans has to be quite different, with particular relevance for the tsunami warning system. The Pacific and Indian Oceans generate ocean-wide tsunamis, but with one major difference. The Indian Ocean, being much smaller in geographical extent than the Pacific Ocean, has shorter tsunami travel times and in the Indian Ocean, reflected waves from the coast lines can interact with subsequent tsunami waves. Hence to determine the maximum tsunami amplitudes in the Indian Ocean, boundary reflections must be taken into account. In the much larger Pacific Ocean, the influence of boundary conditions is somewhat minimal. In the Atlantic Ocean, unlike in the Pacific and Indian Oceans, there are no converging tectonic plates, where tsunamigenic earthquakes could be generated. The mid-Atlantic Ridge is a diverging plate boundary. In the Atlantic Ocean, there are tsunamis only in the marginal seas at the edges. Since tsunamis travel slower in shallow water, Atlantic tsunamis are slow moving, somewhat like a diffusion or a Parabolic process. On the other hand, Pacific tsunamis, which are more influenced by initial conditions, are a Hyperbolic process. Indian Ocean tsunamis, which are strongly influenced by the boundary conditions, have to be modelled as an Elliptic process.

10 illus, 7 ref

007258   Murthy G R (NO, IIIT, Hyderabad) : Towards experimental verification of distributed, spinning/vibrating string energy systems at cosmic level. Int J Syst Cybernetics Inf 2006, (Jan), 9-15.

In the field of cosmology/astro-physics, based on cosmological models, researchers predicted/postulated the existence of hypothetical dark matter in the universe. Describes the discovery of one form of dark matter (that could be experimentally created on earth) and various experiments to study the properties of dark matter. Some experimental procedures which could potentially demonstrate the spinning/vibrating string model of mass/energy units at the cosmic level are described. It is postulated that the recently predicted dark energy (non-radiating energy) will result from spinning/vibrating strings (compacted into the form of massy particles) observed in various forms of dark matter. The dark energy also potentially arises from the energy associated with the vacuum between galaxies and other astronomical bodies. Also based on an empirical quantization law of Bode, procedure to arrive at FINE GRAIN quantization laws for translational harmonics (of spinning/vibrating planet strings as well as solar string) are derived. Then interpreting Kepler's second law properly, procedure to derive fine grain quantization laws for rotational harmonics is described. Using Kepler's third law on a proper time scale rotational and translational harmonics is related. These quantization laws can be readily extended to other astronomical bodies. An important hypothesis about mass/energy units at the atomic and cosmic level is formulated. This hypothesis explains the experimentally observed SIX quarks and one electron. The experimental procedures to verify the hypothesis and thus an attempt at experimental verification of string theory at atomic level are avoided here for brevity and are described in a subsequent paper. The ideas of theoretical model are briefly described.

8 ref

007257   Muraleedharan G;Rao A D;Sinha M;Mahapatra D K (Cent for Atmospheric Sci, Indian Inst of Technol, Delhi, Hauz Khas, New Delhi-110 016) : Analysis of triple collocation method for validation of model predicted significant wave height data. J Indian Geophys Union 2006, 10(2), 79-84.

The validation of the model (Wam, Swan and Nested-Swan) predicted significant wave height data using the new triple collocated statistical method suggests that the predicted values are sufficiently accurate when compared with the buoy measurements. The Wam and Nested-Swan significant wave height estimations give significant positive correlation with deep and shallow water buoy measurements respectively. The linear regression (LR) method is inconsistent and the new method (Functional Relationship, FR) paves way for estimating the variances of the errors in measuring and predicting the physical truth (here significant wave height). The larger the random errors, the larger are the deviations between FR and LR lines. The FR model lines align with the best fit-line (x=y) while comparing the model results and buoy measurements. Also the deviations of the data from the FR model lines are a minimum. Thus FR model as compared to LR model is more realistic when inherent error exists in both cases, measurement by instruments and model predictions.

6 illus, 1 table, 7 ref

007256   Jose M K;Sastry R G (NO, Natn Inst of Hydrology, Jalvigyan Bhawan, Roorkee-247 667, Email: mjose@nih.ernet.in) : Hydraulic potentials due to finite-length line source over an anisotropic aquifer system with inclined bedding planes. J Indian Geophys Union 2006, 10(2), 119-29.

Water resources planning and management require estimation of seepage losses from surface water bodies like streams, rivers and canals to aquifer systems or recharge characteristics of aquifer systems. In such cases, numerical groundwater flow models are not quite capable of simulating flow in anisotropic aquifer systems with inclined planes of stratification. However, analytical results can be useful for simulating hydraulic heads/flow in such systems. An analytical procedure for computing hydraulic heads in such a homogeneous anisotropic aquifer system due to a finite-length surface water source is presented. The procedure has been demonstrated using numerical experiments with the results as equipotential plots. Different coefficients of anisotropy, and orientation of bedding planes have been considered for the illustrations.

4 illus, 2 tables, 12 ref

007255   Deo A A;Ganer D W;Salvekar P S (NO, Indian Inst of Trop Meteorology, Dr. Homi Bhabha Road, Pashan, Pune-411 008, Email: aad@tropmet.res.in) : Sensitivity of oceanic mixed layer to different model resolutions in response to Indian ocean cyclone. J Indian Geophys Union 2006, 10(2), 87-99.

Deals with the numerical investigation of the oceanic upper mixed layer response to Indian Ocean cyclones by changing different model parameters such as horizontal resolution, vertical temperature gradient in a simple 1 1/2-layer wind driven reduced gravity ocean model. The sensitivity experiments are performed for a cyclone moving along a northward track, initially. Cyclones in the Arabian Sea and Bay of Bengal during the year 2004 are chosen. The sensitivity of ocean response to model resolution is examined by increasing the model resolution from 1/2°x 1/2° to 1/8 x 1/8° and 1/12° x 1/12°. Further, the sensitivity to initial vertical temperature gradient is also studied. The model simulated SSTs are compared with the observed SSTs during cyclone period. It is found that the cooling in model SSTs is in agreement with that in the observed SSTs for each case.

9 illus, 15 ref