007128   Singha A;Roy A;Sonkusare A;Pradeep Kumar;Kaul A D (Physics Dep, Indian Institute of Technology, Kharagpur-721 302, Email: anushree@phy.iitkgp.ernet.in) : Measuring nano newton forces with an indigenous atomic force microscope. Curr Sci 2007, 93(8), 1063-70.

Authors demonstrate the ability and limitation of an indigenous AFM, designed and fabricated by for various measurements. In particular, short- and long-range interactions between two surfaces, of different geometrical configurations, have been measured and analysed. Results indicate the reliability of our instrument for measuring forces in the nanonewton scale.

13 illus, 26 ref

007127   Shanta Singh N;Shambhunath Singh W; Dorendrajit Singh;Okram G S (Physics Dep, Manipur College, Imphal-795 008, Email: shantasingh1@yahoo.co.in) : Preparation and characterisation of nanocrystalline CdSe. Indian J Phys 2007, 81(2), 225-31.

Nanostructured CdSe crystals have been prepared by wet chemical method in alkaline medium at 65-70° using cadmium acetate and freshly prepared sodium selenosulphite as Cd and Se ion sources. XRD pattern of the prepared sample shows cubic zinc blende structure with average particle size of 3.4 nm. EDX measurement determines nearly equal atomic concentrations of Cd and Se. The powdered sample of CdSe is characterised using SEM and AFM. Optical absorbance study of thin film of CdSe deposited on glass substrate using chemical bath deposition method shows the blue shift of the band gap of energy of 0.12 eV from the bulk value of 1.7 eV due to quantum confinement effect. The average crystallite size is estimated using effective mass approximation (EMA) as 3.8 nm which agrees well with that obtained using the XRD pattern.

5 illus, 25 ref

007126   Sarkar S K (NO, National Physical Laboratory, New Delhi-110 012, Email: sksarkar@nplindia.ernet.in) : Wave propagation phenomena in troposphere: Indian experience. Indian J Phys 2007, 81(2), 189-215.

The work carried out on tropospheric radio wave propagation has been reviewed. Emphasis has been given on the studies related to radio climatology both for clear air and precipitation, propagation characteristics involving fixed (terrestrial line of sight and transhorizon) and mobile as well as marine communication. Attenuation of radio wave due to water vapour, rain and cloud also has been outlined.

14 illus, 102 ref

007125   Nishti S V;Kunabenchi R S;Suresh Kumar H M; Hanagodimath S M;Biradar J S (Physics Dep, Gulbarga University, Gulbarga-585 106) : Electronic excitation energy quenching of indole derivative by CCl₄ in different solvents. Indian J Phys 2007, 81(2), 251-8.

The electronic excitation energy quenching of 2-phenyl-3-(3'-hydroxythiazolidin-4'-ione-2'-yl) benz(g) indole by carbon tetrachloride (CCl₄) in different solvents viz., n-butanol, dioxane, benzene, methanol, DMF and acetonitrile has been carried out at room temperature to understand nature of quenching mechanism, The Stem-Volmer plots have been found to be linear. The value of probability of quenching per encounter p is found to be less than unity in all the solvents, and the activation energy for quenching `E<sub>a</sub>' is greater than the activation energy of diffusion `E_d'. Hence, it is inferred that the fluorescence quenching mechanism is not solely controlled by the material diffusion.

5 illus, 2 tables, 25 ref

007124   Mehta R V;Patel R;Chudasama B;Desai H B; Bhatnagar S P;Upadhyay R V (Physics Dep, Bhavnagar Univ, Bhavnagar-364 002, Email: rvm@bhavuni.edu) : Magnetically controlled storage and retrieval of light from dispersion of large magnetic spheres in a ferrofluid. Curr Sci 2007, 93(8), 1071-2.

2 illus, 21 ref

007123   Kunnil J;Sarasanandarajah S;Chacko E;Reinisch L (Physics and Astronomy Dep, University of Canterbury, Christchurch, New Zealand) : Solvent effect on autofluorescence of bacillus spores: a comparative study of dry spores and spores in aqueous, glycerol and ethanol suspensions. Sci Soc 2006, 4(2), 151-66.

Fluorescence spectroscopy is a valuable tool in detecting and potentially identifying different bacteria and spores that can be used in bioterrorism. The solvent polarity and local environment Influences the emissions from intrinsic fluorophores. We report the variability of fluorescence of Bacillus globigii (BG) in dried form, in aqueous, and ethanol/ glycerol suspensions. The intrinsic steady-state fluorescence emission spectra of samples were measured at room temperature using the excitation wavelengths 280, 310, 340, 370 and 400 nm with the emission length 130 nm longer than corresponding excitation wavelengths in a scanning spectrofluorometer. For comparison fluorescence of tryptophan is also measured. At 280 nm excitation wavelength the tryptophan emission peaks were near 339,360,348 and 339 nm for dry, aqueous, ethanol and glycerol suspensions respectively. All spectra are normalised to unity. Characteristic information is extracted from spectral fluorescence excitation-emission contours. The aqueous BG spores exhibit a strong maximum in its fluorescence spectrum with the peak excitation wavelength near 320 nm and emission wavelength near 400 nm. When the BG is dried, this peak shifts to approximately 450 nm excitation maximum and 500 nm emission maximum. The ethanol suspension of BG spores exhibits a distinct peak at excitation wavelength 310 nm with emission near 355 nm and in glycerol suspension, peaks occurs near 345 with 300 excitation wavelengths. PCA were done. to discriminate the solvent effect on fluorescence of spores in different environments. Results indicate clear, identifiable differences among spores that are dried, suspended in water, ethanol or in glycerol. These results are important for rapid and automated instrumentation to detect and identify Bacillus. endospores.

5 illus, 45 ref

007122   Gopalakrishna G S;Mahesh M J;Ashamanjari K G (Studies in Geology Dep, University of Mysore, Manasagangotri, Mysore-570 006, Email: gopalakrish2004@yahoo.com) : Thermal and magnetic properties of hydrothermally synthesized K₂ M<. Indian J Phys 2007, 81(2), 233-40.

Potassium bearing copper and nickel pyrophosphate crvstals were synthesized under hydrothermal reaction at relatively moderate P-T conditions. Solubility studies revealed positive thermal coefficient in varied normality (2N - 10N) of H₃PO₄ solvent with relatively high enthalpy. The XRD data is revealed the compounds were crystallized in tetragonal and triclinic system. Thermal properties and minute structural variations of the prepared materials were investigated by DTA and FTIR studies. Magnetic results have revealed that these are frequency and temperature dependent prospective paramagnetic materials.

6 illus, 1 table, 18 ref

007121   Choudhury D K;Dhar P K (Physics Dep, Gauhati University, Guwahati-781 014) : Improved analysis of deep inelastic neutrino data with DGLAP equations at low and high x. Indian J Phys 2007, 81(2), 259-74.

The method of obtaining approximate solutions of DGLAP equations at low and high x reported earlier is re-examined and more general complete solutions are obtained. The formalism which enables one to separate out qualitatively the low x and high x regions explored in deep inelastic scattering is then tested with recent CCFR data with reasonable success.

3 illus, 2 tables, 23 ref

007120   Al Awfi S (Physics Dep, Taibah University, Madina Munawwarah, Saudi-Arabia, Email: alawfi99@hotmail.com) : Effect of phase fluctuations of a laser on the dynamic process of an atom near a metallic layer. Indian J Phys 2007, 81(2), 241-50.

The effect of phase fluctuations of a laser on the atomic reflection of evanescent light is investigated. This effect is one of the main factors that limit the performance of the atomic mirror action obstructing the ultimate goal of near-perfect coherent reflection process. It is concluded that this effect plays a significant role hence should be incorporated in the treatment of quantum dynamics. By operating at low intensities, that could be achieved by the addition of thin metallic layer, these effects can only be minimized. Based on these considerations, the atomic mirror action is determined.

6 illus, 26 ref

005958   Yusoff A R M;Syahrul M N;Henkel K (NO, , Malaysia Energy Centre, 8th Floor, North Wing, 7, Jalan Tasik, The Mines Resort City, 43300 Seri Kembangan, Selangor Dar, Email: abdrashid_4@yahoo.com) : Film adhesion in amorphous silicon solar cells. Bull Mater Sci 2007, 30(4), 329-31.

Film adhesion in amorphous silicon solar cells made on different polyimide substrats (Kapton VN, Upilex-S and Gouldflex), and the effect of tie coats on film adhesion has been presented.

5 illus, 4 ref

005957   Uddin W;Joshi B;Kumar T S;Sharma S;Sagar R (NO, Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital-263 129, Email: wahab@aries.ernet.in) : Observations of total solar eclipse of 29 march 2006 and related atmospheric measurements. Curr Sci 2007, 93(7), 957-9.

Authors report preliminary results on short-period oscilla-tions in the corona and changes in the earth's atmospheric parameters, observed during a total solar eclipse of 29 March 2006 from Manavgat, Turkey.

5 illus, 7 ref

005956   Sudhakar Reddy B;Buddhudu S (Physics Dep, Sri Venkateswara Univ, Tirupati-517 502, Email: profsb_svuniv@hotmail.com ) : Spectral analysis of Cu<. Bull Mater Sci 2007, 30(5), 481-6.

Reported development and spectral analysis of Cu²⁺ (0.5 mol%) and Mn²⁺ (0.5 mol%) ions doped in two new series of glasses. The visible absorption spectra of Cu<6>2+ and Mn²⁺ glasses have shown broad absorption bands at 820 nm and 495 nm, respectively. For Cu²⁺ BFP glasses, excitation at 380 nm, a blue emission at 441 nm and also a weak emission at 418 nm ions have been observed. For Mn²⁺ ions doped BFP glasses, excitation at 410 nm and a red shift at 605 nm emission have been observed.

6 illus, 34 ref

005955   Shah N;Dolly Singh;Shah S;Qureshi A;Singh N L;Singh K P (Physics Dep, Baroda M.S. Univ, Vadodara-390 002, Email: singhnl_msu@yahoo.com) : Study of microhardness and electrical properties of proton irradiated polyethersulfone (PES). Bull Mater Sci 2007, 30(5), 477-80.

Polyethersulfone (PES) films were irradiated with 3 MeV proton beams in the fluence range 10¹³-10¹⁵ ions/cm². The radiation induced changes in microhardness was investigated by a Vickers' microhardness tester in the load range 100-1000 mN and electrical properties in the frequency range 100 Hz-1 MHz by an LCR meter. It is observed that microhardness of the film increases significantly as fluence increases up to 10¹⁴ ions/cm². The bulk hardness of the films is obtained at a load of 400 mN. The increase in hardness may be attributed to the cross linking effect. There is an exponential increase in conductivity with log frequency and the effect of irradiation is significant at higher fluences. The dielectric constant/loss is observed to change significantly due to irradiation. It has been found that dielectric response in both pristine and irradiated samples obey the Universal law and is given by ξα_f^n-1. These results were corroborated with structural changes observed in FTIR spectra of irradiated samples.

5 illus, 13 ref

005954   Samir O M;Somashekar R (Studies in Physics Dep, Mysore Univ, Manasagangotri, Mysore-570 006, Email: rs@uomphysics.net) : Crystal structure and elastic constants of Dharwar cotton fibre using WAXS data. Bull Mater Sci 2007, 30(5), 503-10.

Wide-angle X-ray scattering (WAXS) recordings were carried out on raw Dharwar cotton fibres available in Karnataka. Using this data and employing linked atom least squares (LALS) method, we report here the molecular and crystal structure of these cotton fibres. Employing structural data, Computed elastic moduli tensor components of these fibres. From these investigations, it turns out that the intrinsic strains present in the fibre arise due to hydrogen bonds and not covalent bonds, which is a significant result.

4 illus, 4 tables, 34 ref

005953   Ramamanohar Reddy N;Venkata Ramana M; Krishnaveni K;Siva Kumar K V;Murthy V R K (Physics Dep, Sri Krishnadevaraya Univ, Anantapur-505 003, Email: sivakumar.sivani@gmail.com ) : Dielectric, elastic, anelastic and conductivity behaviour of ferroelectromagnetic composites, Ni_0.5Zn_0.5Fe_1.95O_4-δ< B>+ Ba_0.8Pb_0.2TiO₃. Bull Mater Sci 2007, 30(4), 357-63.

Ferroelectromagnetic composites with compositions, X Ni_0.5ZnFe_1.95O_4-<100>F255> + (1 - X) Ba_0.8Pb_0.2TiO₃, in which X varies as 0, 0 005, 0.010, 0.015, 0.020, 0.040, 0.060, 0.080 and 1 in mole %, were prepared by conventional ceramic double sintering process. The presence of two phases was confirmed by X-ray diffraction. The temperature variation of dielectric constant, ε, dielectric loss, tan δ, d.c. conductivity, a.c. conductivity, elastic and anelastic behaviour of ferrite-ferroelectric composites were studied in the temperature range 30-350øC. The a.c. conductivity measurements on these composites in the frequency range 100 Hz-1 MHz at room temperature reveal that the conduction mechanism is due to small polaron hopping. The dielectric and elastic data were discussed in the light of phase transitions.

7 illus, 32 ref

005952   Meena Devi J;Gayathri N;Bharathi A; Ramachandran K (School of Physics, Madurai Kamaraj Univ, Madurai-625 021, Email: jmeenadevi@rediffmail.com) : Effect of nickel substitution on thermal properties of Na_0.9CoO₂. Bull Mater Sci 0000, 30(4), 345-8.

Effect of nickel substitution in Na_0.9CoO₂ by examining their thermal properties at room temperature has been reported. Experimental results indicate that thermoelectric efficiency is enhanced upon nickel substitution in sodium cobaltate.

3 illus, 1 table, 14 ref

005951   Madhukumar K;Varma H K;Manoj K;Elias T S; Padmanabhan V;Nair C M K (Physics Dep, Mahatma Gandhi College, Thiruvananthapuram-695 004, Email: madhusandh@yahoo.co.in) : Photoluminescence and thermoluminescence properties of tricalcium phosphate phosphors doped with dysprosium and europium. Bull Mater Sci 2007, 30(5), 527-34.

The suitability of calcium phosphate crystals for thermoluminescence dosimetry (TLD) applications is investigated, owing to their equivalence to bone mineral. The α and β phases of tricalcium phosphate (TCP) were synthesized through wet precipitation and high temperature solid state routes and doped with Dy and Eu. The photoluminescence and thermoluminescence studies of the phosphors have been carried out. The TL properties were found to be highly dependent on the method of preparation of the material. Eu doping gave good PL emission, whereas Dy doping was more efficient in TL emission. β TCP was found to be less TL sensitive than α-TCP, yet it was identified as a better phosphor material owing to its better fading characteristics. The dependence of TL of β-TCP: Dy on the energy and dose of radiation, and on the doping concentration were studied. The TL intensity was observed to fade exponentially during a storage period of 20 days, but it stabilized at 70% of the initial value after 30 days. The optimum doping concentration was found to be 0.5 mol%.

10 illus, 20 ref

005950   Gunasekaran S;Anbalagan G (Physics PG and Research Dep, Presidency College, Chennai-600 005, Email: anbu24663@yahoo.co.in) : Thermal decomposition of natural dolomite. Bull Mater Sci 2007, 30(4), 339-44.

Thermal decomposition behaviour of dolomite sample has been studied by thermogravimetric (TG) measurements. Differential thermal analysis (DTA) curve of dolomite shows two peaks at 777.8°C and 834°C. The two endothermic peaks observed in dolomite are essentially due to decarbonation of dolamite and calcite, respectively. The TG data of the decomposition steps have also been analysed using various differential, difference-differential and integral methods, viz. Freeman-Carroll, Horowitz-Metzger, Coats-Redfern methods. Values of activation entropy, Arrhenius factor, and order of reaction have been approximated and compared. Measured activation energies vary between 97 and 147 kJ mol^-1. The large fluctuation in activation energy is attributed to the presence of impurities such as SiO₂, A1₂O₃, Fe₂O₃, Cl^- etc in the samples. FTIR and XRD analyses confirm the decomposition reaction. SEM observation of the heat-treated samples at 950øC shows cluster of grains, indicating the structural transformation.

5 illus, 6 tables, 31 ref

005949   Gudage Y G;Deshpande N G;Sagade A A;Sharma R P;Pawar S M;Bhosale C H (Physics Dep, Dr B A Marathwada Univ, Aurangabad-431 004, Email: ramphalsharma@yahoo.com) : Photoelectrochemical (PEC) studies on CdSe thin films electrodeposited from non-aqueous bath on different substrates. Bull Mater Sci 2007, 30(4), 321-7.

Thin films of CdSe were deposited by potentiostatic mode on different substrates such as stainless steel, titanium and fluorine tin-oxide (FTO) coated glass using non-aqueous bath. The preparative parameters were optimized to get good quality CdSe thin films. These films were characterized by X-ray" diffraction (XRD), optical absorption and photoelectrochemical (PEC) techniques. XRD study revealed that the films were polycrystalline in nature with hexagonal phase. Optical absorption study showed that CdSe films were of direct band gap type semiconductor with a band gap energy of 1.8 eV. PEC study revealed that CdSe film depo-sited on FTO coated glass exhibited maximum values of fill factor (FF) and efficiency (η) as compared to the films deposited on stainless steel and titanium substrate.

7 illus, 4 tables, 26 ref

005948   Debnath S;Islam M R;Khan M S R (Applied Physics and Electronic Engineering Dep, Rajshahi Univ, Rajshahi 6205, Bangladesh, Email: msrkhan2003@yahoo.com) : Optical properties of CeO₂ thin films. Bull Mater Sci 2007, 30(4), 315-19.

Cerium oxide (CeO₂) thin films have been prepared by electron beam evaporation technique onto glass substrate at a pressure of about 6 x 10^-6 Torr. The thickness of CeO₂ films ranges from 140-180 nm. The optical properties of cerium oxide films are studied in the wavelength range of 200-850 nm. The film is highly transparent in the visible region. It is also observed that the film has low reflectance in the ultra-violet region. The optical band gap of the film is determined and is found to decrease with the increase of film thickness. The values of absorption coefficient, extinction coefficient, refractive index, dielectric constant, phase angle and loss angle have been calculated from the optical measurements. The X-ray diffraction of the film showed that the film is crystalline in nature. The crystallite size of CeO₂ films have been evaluated and found to be small. The experimental d-values of the film agreed closely with the standard values.

11 illus, 17 ref

005947   Bal S;Samal S S (Physics Dep, National Institute of Technology, Rourkela-769 008, Email: smrutisikha_bal@yahoo.com) : Carbon nanotube reinforced polymer composites-a state of the art. Bull Mater Sci 2007, 30(4), 379-86.

Corbon nanotubes (CNTs) are being considered as nanoscale fibres to enhance the performance of polymer composite materials because of their high mechenical strength. Novel CNT-based composites have been fabricated using different methods, expecting that the resulting composites would possess enhanced or completely new set of physical properties due to the addition of CNTs. However, the physics of interactions between CNT and its surrounding matrix material in such nano-composites has yet to be elucidated and methods for determining the parameters controlling interfacial characteristics such as interfacial shear stress, is still challenging. An improvement of the physical properties of polymer nanocomposites, based on carbon nanotubes (CNTs), is addicted to a good dispersion and strong interactions between the matrix and the filler.

14 illus, 44 ref

005946   Alsaad A M;Ahmad A A (Physical Sciences Dep, Jordan Univ Science & Technology, P.O. Box 3030, Irbid-221 100, Email: sema@just.edu.jo) : Structural phase transitions and piezoelectric anomalies in ordered Sc_0.5Ga_0.5N alloys. Bull Mater Sci 2007, 30(4), 407-13.

Local-density approximation calculations (LDA) within density functional theory (DFT). and Berry phase approach within modern theory of polarization are performed to predict the structural and piezoelectric properties of ordered Sc_0.5Ga_0.5N alloys under compressive and tensile in-plane strain. This alloy is found to exhibit a tremendous piezoelectric response, associated with a phase transition from nonpolar p6₃/mcc(D_{6h) space group to a polar p63mc(C6v) structure, at fixed Ga and Sc compositions when continuously changing the experimental accessible parameters (i.e. the compressive and tensile strain). The mechanism of the effects behind such anomalous behaviour is revealed and explained.}

4 illus, 40 ref

005945   Ahmad A A;Alsaad A M (Physical Sciences Dep, Jordan Univ Science and Technology, P.O. Box 3030, Irbid 22110, Email: sema@just.edu.jo) : Adhesive B-doped DLC films on biomedical alloys used for bone fixation. Bull Mater Sci 2007, 30(4), 301-8.

Grade 316L stainless steel and grade 5 titanium alloy (Ti-6AI-4V) were used as biomaterial substrates. They were coated with DLC films containing boron additives at various levels using various Si interfacial layer thicknesses. The best film adhesion was achieved at 8% and 20% on DLC coated Ti-6A1-4V and grade 316L substrates, respectively. It has been demonstrated that doping the DLC with boron increases their adhesion strength to both substrates even without silicon interfacial layer and increases it substantially with optimum silicon layer thickness. The adhesion strength is also correlated with the hydrogen contents in the B-DLC films. It is found to reach its maximum value of 700 kg/cm² and 390 kg/cm² at 2/7 and 3/6 for CH₄/Ar partial pressures (in mTorr ratio) for Ti-6A1-4V and 316L substrates, respectively.

6 illus, 2 tables, 31 ref

004945   Ray A;Barat P;Mukherjee P;Sarkar A; Bandyopadhyay S K (Variable Energy Cyclotron Centre, , 1/AF, Bidhan Nagar, Kolkata-700 064, Email: pbarat@veccal.ernet.in) : Effect of transient change in strain rate on plastic flow behaviour of low carbon steel. Bull Mater Sci 2007, 30(1), 69-71.

Plastic flow behaviour of low carbon steel has been studied at room temperature durign tensile deformation by varying the initial strain rate of 3.3 x 10^-4s^-1 to a final strain reate ranging from 1.33 x 10^-3s^-1 to 2 x 10^-3s^-1 at a fixed engineering strain of 12%. Haasen plot revealed that the mobile dislocation density remained almost invariant at the juncture where there was a sudden increase in stress with a change in strain rate and the plastic flow was solely dependent on the velocity of mobile dislocations. In that critical regime, the ariation of stress with time was fitted with a Boltzmann type Sigmoid function. The increase in stress was found to increase with final strain rate and the time elapsed in attaining these stress value showed a decreasing trend. Both of these parameters saturated asymptotically at a higher final strain rate.

4 illus, 16 ref

004944   Ramana Reddy M V;Gopal Reddy C;Narasimha Reddy K (Dep. of Physics, Post-Graduate college of Science, Osmania University, Hyderabad 500 004) : Thermoluminescence characteristics of Sm<. Bull Mater Sci 2007, 30(1), 1-3.

Thermoluminescence (TL) characteristics of NaYF₄ crystals doped with Sm³⁺ have been studied after γ-ray irradiation. Dependence of luminescence efficiency on Sm³⁺ concentration and radiation dose has been measured and possible applications of NaYF₄:Sm³⁺ as a novel phosphor for TL dosimetry have been investigated. the efficiency of 0.3 mole % Sm³⁺ doped NaYF₄ crystal has been found to be maximum and comparable with commercial thermoluminescence dosimetric (TDL) materials.

3 illus, 7 ref

004943   Narayana Reddy C;Asokan S;Anavekar R V (Dep of Physics, Bangalore Univ, Bangalore-560 056, Email: anavekar_271@yahoo.co.in) : High field electrical behaviour in lithium-phospho-vanadate glass system. Bull Mater Sci 2007, 30(1), 65-8.

High field electrical switching behaviour of lithium-phospho-vanadate glasses has been studied by determining the current-voltage characteristics. The investigated glasses exhibit temperature, thickness and composition dependent trends. At low current, the I-V characteristics obey Ohm's law followed by a negative resistance region where the bulk behaviour dominates and at higher values of current the sample goes to a low resistance state. The studied glasses exhibit memory type switching. It is suggested that electrical switching is due to the formation of conducting channels that are due to electronic origin while thermal effects dominate once the channels are formed resulting is crystallization.

4 illus, 2 tables, 15 ref

004942   Mangal R K;Tripathi B;Singh M;Vijay Y K (Dep of Physics, University of Rajasthan, Jaipur 302 004) : Annealing effects in Al-Sb bilayer thin films. Bull Mater Sci 2007, 30(1), 5-7.

Presents preparation and characterization of Al-Sb bilayer thin films. Thin films of thicknesses, 3000/1000 Å and 3000/1500 Å, were obained by the thermal evaporation (resistive heating) method. vacuum annealing and rapid thermal annealing methods were used to mix bilayer thin film structure. Results obtained from optical band gap data and Rutherford back scattering spectrometry showed mixing of Al-Sb bilayer system.

2 illus, 1 table, 14 ref

004941   Deshmukh S H;Burghate D K;Akhare V P; Deogaonkar V S;Deshmukh P T;Deshmukh M S (Dep of Physics, Shri Shivaji Science college, Amravati-444 603) : Electrical conductivity of polyaniline doped PVC-PMMA polymer blends. Bull Mater Sci 2007, 30(1), 51-6.

Electrical conductivity of polyaniline doped polyvinylchloride (PVC) and poly (methyl methacrylate) (PMMA) thin films has been measured by studying the I-V characteristics at various temperatures in the range 323-363 K. The results are presented in the form of I-V characteristics and analysis has been made by interpretation of Poole-Frenkel, Fowler-Nordheim, Schottky In(J) vs T plots, Richardson and Arrhenius plots. The analysis of these results suggests that Schottky and Richardson mechanisms are primarily responsible for the observed conduction.

8 illus, 26 ref

004940   Benny Joseph;Menon C S (School of Pure and Applied Physics, Mahatma Gandhi Univ, Kottayam-686 560, Email: sjvben@yahoo.com) : Optical properties and surface morphology of nickel phthalocyanine thim films. E J Chem 2007, 4(2), 255-64.

Thin films of Nickel Phthalocyanine (NiPc) are fabricated at a base pressure of 10^-5 m.bar using Hind-Hivac thermal evaporation plant. The films are deposited on to glass substrates at various temperatures 318, 363, 408 and 458K. The optical absorption spectra of these thin films are measured. Present studies reveal that the optical band gap energies of NiPc thin films are highly dependent on the substrate temperatures. The structure and surface morphology of the films deposited on glass substrates of temperatures 303, 363 and 458K are studied using X-ray diffractograms and Scanning Electron Micrographs (SEM), show that there is a change in the crystallinity and surface morphology due to change in the substrate temperatures. Full width at half maximum (FWHM) intensity of the diffraction peaks is also found reduced with increasing substrate temperatures. Scanning electron micrographs show that these crystals are fiber like at high substrate temperatures. The optical band gap increases with increase in substrate temperature and is then reduced with fiber-like grains at 408K. The band gap increases again at 458K with full of fiber like grains. Trap energy levels are also observed for these films.

8 illus, 3 tables, 28 ref

004065   Yadav R K;Shanker R (Atomic Physics Laboratory, Physics Dep, Banaras Hindu Univ, Varanasi-221 005, Email: rshanker@bhu.ac.in) : Energy and angular distributions of backscattered electrons from collisions of 5 ke V electrons with thick Al, Ti, Ag, W and Pt targets. Pramana J Phys 2007, 68(3), 517-28.

The energy and angular distributions of backscattered electrons produced under the impact of 5 keV electrons with thick Al, Ti, Ag, W and Pt targets are measured. The energy range of backscattered electrons is considered between E_B = 50 eV and 5000 eV. The angle of incidence a and take-off angle θ are chosen to have values α = 0° and 10° and θ = 100°, 110° and 120° respectively. The measured energy spectra are compared with the available theoretical models for α = 0° and 10°. The elastic peak intensity of backscattered electrons is found to be a function of angle of incidence, take-off angle and atomic number of the target material. The considered theories are reasonably in good agreement with experiment for the energy spectra of the backscattered electrons having their reduced energies ε(= E_B/E₀) in the range of 0.20 to 1.00.

6 illus, 30 ref

004064   Yadav R K;Shanker R (Atomic Physics Laboratory, Physics Dep, Banaras Hindu Univ, Varanasi-221 005, Email: rshanker@bhu.ac.in) : Contribution of backscattered electrons to the total electron yield produced in collisions of 8-28 keV electrons with tungsten. Pramana J Phys 2007, 68(3), 507-15.

It is shown experimentally that under energetic electron bombardment the backscattered electrons from solid targets contribute significantly (<126>80%) to the observed total electron yield, even for targets of high backscattering coefficients. It is further found -that for tungsten (Z = 74) with a backscattering coefficient of about 0.50, about 20% of the total electron yield is contributed by the total secondary electrons for impact energies in the range of 8-28 keV. The yield of true backscattered electrons at normal incidence (770), total secondary electrons (δ) and the total electron yield (δ_tot) produced in collisions of 8-28 keV electrons with W have been measured and compared with predictions of available theories. The present results indicate that the constant-loss of primary electrons in the target plays a significant role in producing the secondary electrons and that it yields a better fit to the experiment compared to the power-law.

3 illus, 27 ref

004063   Wagner V et al (NO, Nuclear Physics Institute of AS CR, CZ-25068 Rez, Czech Republic, Email: wagner@ujf.cas.cz ) : The possibility to use 'energy plus transmutation' set-up for neutron production and transport benchmark studies. Pramana J Phys 2007, 68(2), 297-306.

Set-up 'energy plus transmutation', consisting of a thick lead target and a natural uranium blanket, was irradiated by relativistic proton beams with the energy from 0.7 GeV up to 2 GeV. Neutron field was measured in different places of this setup using different activation detectors. The possibilities of using the obtained data for benchmark studies are analyzed. Uncertainties of experimental data are shown and discussed. The experimental data are compared with results of simulation with MCNPX code.

8 illus, 1 table, 7 ref

004062   Vijaya Bhasker Reddy P;Lalitha G;Raman Reddy M V;Reddy G (Physics Dep, Osmania Univ, Hyderabad-500 007) : Elastic behavior of sol-gel prepared lithium-zinc ferrites. Acta Cienc Indica-Phys 2007, 33(2), 183-7.

A series of Lithium-Zinc ferrites, with compositional formula, Li_0.5-x/2 Zn_x Fe_2.5-x/2 O₄ (where x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by sol gel route and were later characterized structurally by XRD. The samples are found to have spinel structure with no detectable impurity phase. After measuring their bulk densities, the ultrasonic longitudinal (V_l) and shear velocities (V_s) have also been measured at room temperature using the pulse transmission technique. Using the ultrasonic data, the values of Young's and rigidity moduli along with Poisson's ratio and Debye temperatures have been calculated. Further, as the materials are porous, zero porous elastic moduli have also been arrived at using a well-known model. The observed elastic behavior of these materials is explained.

2 illus, 3 tables, 7 ref

004061   Titarenko Y E;Batyaev V F;Zhivun V M; Kudryashov V O;Lipatov K A;Ignatyuk A V;Mashnik S G (NO, Institute for Theoretical and Experimental Physics-117 218, , Email: yuri.titarenko@itep.ru) : Excitation functions of residual nuclei production from 40-2600 MeV proton-irradiated <. Pramana J Phys 2007, 68(2), 289-95.

The work is aimed at experimental determination of the independent and cumulative yields of radioactive residual nuclei produced in intermediate-energy proton-irradiated thin targets made of highly isotopic enriched and natural lead (^{206,207,208,nat}pb) and ²⁰⁹Bi. 5972 radioactive product nuclide yields have been measured in 55 thin targets induced by 0.04. 0.07, 0.10, 0.15, 0.25, 0.6, 0.8, 1.2, 1.4, 1.6 and 2.6 GeV protons extracted from the ITEP U-10 proton synchrotron. The measured data have been compared with data obtained at other laboratories as well as with theoretical simulations by seven codes. It is found that the predictive power of the tested codes is different but is satisfactory for most of the nuclides in the spallation region, though none of the codes agree well with the data in the whole mass region of product nuclides and all should be improved further.

1 illus, 5 tables, 9 ref

004060   Tikekar R;Jotania K (NO, Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Pune-411 007, Email: tikekar@iucaa.ernet.in) : On relativistic models of strange stars. Pramana J Phys 2007, 68(3), 397-406.

The superdense stars with mass-to-size ratio exceeding 0.3 are expected to be made of strange matter. Assuming that the 3-space of the interior space-time of a strange star is that of a three-paraboloid immersed in a four-dimensional Euclidean space, authors obtain a two-parameter family of their physically viable relativistic models. This ansatz determines density distribution of the interior self-gravitating matter up to one unknown parameter. The Einstein's field equations determine the fluid pressure and the remaining geometrical variables. The information about mass-to-size ratio together with the conventional boundary conditions lead to the determination of total mass, radius and other parameters of the stellar configuration.

4 illus, 2 tables, 20 ref

004059   Thakur A K;Srivastava K (Research Scholar, Lalit Narayan Mithila Univ, K. Nagar, Darbhanga-846 004) : Realization of SC active all pass transfer function with varied topologies for sensitivity minimization. Acta Cienc Indica-Phys 2007, 33(2), 215-19.

Recent development of switched capacitor resistor (SCR) has brought revolutionary changes in traditional active networks. The SC filters provide a high degree of achievable accuracy. Synthesis of SC all pass filter will be realized following its active counterpart. The sensitivity of the SC network will also be described as main topic of discussion.

2 illus, 7 ref

004058   Sundriyal Y P;Tripathi J K;Sati S P;Rawat G S;Srivastava P (Geology Dep, H.N.B. Garhwal Univ, Srinagar (Garhwal)-246 174, Email: pradeep@wihg.res.in) : Landslide-dammed lakes in the Alaknanda basin, lesser Himalaya: causes and implications. Curr Sci 2007, 93(4), 568-74.

Authors present observations on landslide-dammed lake deposits located in the vicinity of the E-W and NW-SE trending, south-dipping North Almora Thrust, in the Alaknanda Basin around Srinagar Garhwal. Preliminary observations suggest that activation of crumpled and unstable phyllite dominated slopes led to temporary damming of second and third order tributaries of the Alaknanda river. Sedimentary styles of the succession indicate deposition under the transient lacustrine environment, with seasonality. Luminescence chronology suggests that the lakes were formed after the Last Glacial Maximum (LGM) and probably continued till the Mid-Holocene. Lake formation is attributed to the reactivation of phyllite-dominated slopes following the reestablishment of the southwest monsoon after the LGM. Presence of contorted laminas is interpreted as episodic events of seismic activity. Finally the lakes disappeared due to large-scale slope reactivation around Mid-Holocene.

8 illus, 1 table, 27 ref

004057   Sinha S;Singh H S;Mishra L K (Physics Dep, A.N. College, Patna,Bihar) : An evaluation of temperature dependent absorption coefficient α (h, ω) for mercuy cadmium telluride Hg1-xCdx Te as a function of photon energy hω. Acta Cienc Indica-Phys 2007, 33(2), 141-52.

Using the theoretical formalism of Amirthraj and Burnell evaluated the temperature dependent absorption coefficient α(h , ω) as a function of photon energy h ω. The theoretical results are in good agreement with that of the experimental data and also from the other works.

1 illus, 4 tables, 42 ref

004056   Sinha B O P;Murari A (Physics Dep, Vinoba Bhave Univ, Hazaribag Jharkhand) : An evaluation of inelastic scattering time τ in for noble metal thin films and thin wire as a function of temperature T. Acta Cienc Indica-Phys 2007, 33(2), 221-8.

Inelastic scattering time τ_in for noble metals thin films were evaluated using the theoretical formalism of M. Kaveh and M. Wiser. Theoretical results for noble metal thin films are in good agreement with the experimental data as well as with other workers.

4 tables, 38 ref

004055   Sinha A K;Singh S K;Jha M P;Mishra L K (Physics Dep, Magadh Univ, Bodh-Gaya-824 234) : An evaluation of transition temperature T amorphous T₅T₉ transition-metal alloys. Acta Cienc Indica-Phys 2007, 33(2), 273-80.

Using McMillan equation for electron-phonon transition temperature T_c of several amorphous transition metal alloys (T₅T₀) were calculated using the value of θ_D and μ. The value of electron phonon parameter λ was also determined by using Ginzburg-Landau, Abrikosov-Gorlcov {GLAG) theory. Our theoretical evaluated values of T_c are in good agreement with those of the experimental data and also with other workers.

4 tables, 42 ref

004054   Sinha A K;Singh S K;Jha M P;Mishra L K (Physics Dep, Magadh Univ, Bodh-Gaya-824 234) : An evaluation of coherence length ξ(O)electron-phonon coupling parameterλ and density of states at the fermi level N (E_f) of amorphous La-Al alloys. Acta Cienc Indica-Phys 2007, 33(2), 205-13.

Coherence Length ξ, (0), electron-phonon coupling parameter λ and density of states N (E_r) at the Fermi Surface were calculated by using well known formula used for these parameters for different percentage of Al in La -Al alloys. The theoretical results are in good agreement with those of the earliest workers and also with the experimental data.

4 illus, 2 tables, 26 ref

004053   Singh P et al (Nuclear Physics Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: psingh@barc.gov.in) : Accelerator development in India for ADS programme. Pramana J Phys 2007, 68(2), 331-42.

At BARC, development of a Low Energy High Intensity Proton Accelerator (LEHIPA), as front-end injector of the 1 GeV accelerator for the ADS programme, has been initiated. The major components of LEHIPA (20 MeV, 30 mA) are a 50 keV ECR ion source, a 3 MeV Radio Frequency Quadrupole (RFQ) and a 20 MeV drift tube linac (DTL). The Low Energy Beam Transport (LEBT) and Medium Energy Beam Transport (MEBT) lines match the beam from the ion source to RFQ and from RFQ to DTL respectively. Design of these systems has been completed and fabrication of their prototypes has started. Physics studies of the 20-1000 MeV part of the Linac are also in progress.The present status of this project is presented.

13 illus, 14 tables, 1 ref