013219   Annadurai V;Sangappa;Somashekar R (Studies in Physics Dep, Mysore Univ, Manasagangotri, Mysore-570 006, Email: rs@uomphysics.net) : Rate of recovery of long periodicity in stretched muscle specimen using SAXS data. J Polym Mater 2004, 21(4), 439-44.

An expression for scattered X-ray intensity from one-dimensional Hosemann's linear paracrystalline model consisting of alternate crystalline and amorphous regions has been reduced to easily computational form by employing exponential distribution function here. This theoretical approach to analyse the lwamoto et al's SAXS data of stretched frog muscle fibers obtained at every millisec from the released state and hence to compute the long periodicity of myosin along with the rate of recovery of this muscle fiber for the first time. It was found that the changes are linear in nature. The width of the crystalline phase length distribution does not vary with the released time indicating the changes are within the layer wherein the chain unfolds at the rate of 1.15 Angstrum/ms in myosin fibers. Fraction of amorphous component which we have computed on the basis of paracrystalline model has been reported. The parameters which are related to nucleation growth rates, growth geometry and type of nucleation have been computed using Avrami equation. These results have been compared with the values observed for polymers.

4 illus, 1 table, 14 ref

013218   Alam M;Mondal S K;Uddin R;Ahmad G (Mathematics and Physics Dep, East West University, Dhaka, Bangladesh, Email: alam2204@yahoo.com) : Internal radiation absorbed dose estimation in human brain due to techenetium-99m and iodine-131. J med Phys 2004, 29(2), 77-9.

Internal dosimetry is a branch of medical physics that deals with the measurement of the internally absorbed dose by an organ after applying isotopes. In this study, internal radiation absorbed dose has been calculated for ^99mTc and ¹³¹I, which are frequently used for functioning tests and therapeutic treatments of thyroid, respectively. In these cases, some amount of isotopes are accumulated in other tissues like brain, which are very soft and cannot be regenerated if they are damaged. Using ionizing radiation inside the body and to ensure the safety of brain, the internal radiation absorbed dose has been calculated applying direct counting measurement. Accumulation of isotopes to target organ has been measured and this target organ is considered as primary target organ; also this organ is considered as source with respect to other organs. These organ counts have been measured by computer-based scintillation system. The amount of exposure in brain has been measured with the help of the data obtained from the special set-up equipment, including Nal detector, radiation survey meter and water phantoms of various sizes. Absorbed dose in brain for each isotope has been calculated by applying time-activity curve analysis. Finally, these results have been compared with the data in ICRP Reports 53 and 71.

2 illus, 11 ref

013217   Akkurt I (Suleyman Demirel University Fen-Edehiyat Fak, , Fizik B51, Isparta, Turkey) : Calibration of a TOF spectrometer in neutron measurements. Indian J Phys 2004, 78(11), 1239-42.

Calibration procedure of a time-of-flight (TOF) spectrometer used in neutron measurements at Maxlab, is described. This includes both pulse height and neutron flight time which is important in neutron energy determinations. The pulse is recorded by ADC and time information is recorded by TDC in electronic system.

6 illus, 13 ref

013216   Abu-Issa M S;Leghrouz A A;Elias E I; Barghouthi I A (Dep of Physics, Al-Quds University, P. O. Box 20002, Jerusalem, Palestine, Email: abuissal2@Yahoo.com) : O<. Indian J Phys 2004, 78(12), 1303-7.

Used Monte Carlo simulations of O⁺ ion temperature in the auroral ionosphere (200 km - 450 km) to calculate O⁺-O collision frequency and O⁺-O⁺Coulomb self-collision frequency. The Monte Carlo model used includes O⁺-O resonant charge exchange and polarization collisions as well as O⁺-O⁺ Coulomb self-collisions; it also includes the effect of ExB drift. The variations of O⁺ temperature, O⁺-O and O⁺-O⁺ collision frequencies are discussed with respect to the electric field and at different altitudes. Finaly that in the auroral ionosphere O⁺temperature increases as electric field increases due to O⁺ frictional heating with the neutrals O. For increasing O⁺ temperature, the O⁺-O collision frequency increases for a constant altitude while the O⁺-O⁺ Coulomb self-collision frequency decreases. The relative importance of collision frequencies in the auroral ionosphere is discussed.

4 illus, 21 ref

012279   Yadav S;Bandyopadhyay A K;Gupta V K;Gupta A C (Pressure & Vacuum Standards, National Physical Laboratory, New Delhi-110 012) : A glimpse of national standards for hydrulic pressure measurements. Bhartiya Vaigyanik Evam Audyogik Anusandhan Patrika 2004, 12(2), 340-1.

Since last two decades, Pressure and Vacuum Standards Group of National Physical Laboratory, New Delhi is actively engaged in the research and developmental activities in pressure metrology, establishment, development, maintenance and upgradation of pressure standards. The paper highlights the glimpse of the national hydraulic pressure standards established and maintained at National Physical Laboratory, New Delhi. The international, bilateral and mutual in-house laboratory traceability of these national standards is also described.

012278   Yadav B C;Shukla R K;Bali L M (Opto-Electronic Research Laboratory, Department of Physics, University of Lucknow, Lucknow-226 007, Email: balchandra_yadav@rediffmail.com) : Sol-gel processed TiO₂ films on U-shaped glass-rods as optical humidity sensor. Indian J pure appl Phys 2005, 43(1), 51-5.

The fabrication and characterization of a thick-film optical humidity sensor based on the semiconducting metal-oxide TiO₂ have been described. The sensor element consists of a thin U-shaped borosil glass-rod having different curvature with a film of TiO₂ deposited on it. The films prepared are dried and annealed at 600°C for two hours, which make them rutile, porous and very sensitive to humidity. Both the ends of the U-shaped glass-rods are coupled to optical fibers. Light from a He-Ne laser is launched in to the sensing element through one of them. Light received from the other fibre is fed into an optical power meter. Variations in the intensity of light with changes in humidity from 5% to 95% have been recorded.

8 illus, 25 ref

012277   Tripathi P S M;Tiwari S N;Mishra K K;Tripathi N (NO, Central Fuel Research Institute, P.O. - F.R.I., Dhanbad-828 108) : Effect of gamma irradiation on the thermal decomposition behaviour and electrical resistivity of some Indian lignite and bituminous coals. Bhartiya Vaigyanik Evam Audyogik Anusandhan Patrika 2004, 12(2), 335.

012276   Suresh Kumar A;Manjubhashini A B (USIC, S V University, Tirupati-517 502) : Spectral properties of different concentrations of Nd<. Indian J pure appl Phys 2005, 43(1), 17-20.

Multi-component oxide glass systems of barium lead borophosphate with 0.01-0.05 mol% of Nd³⁺ ion were prepared using meltquenching technique. The absorption spectral profile of these glasses in the UV-VIS regions was used to determine the spectroscopic characteristic parameters such as Racah (E¹, E², E³), spin orbit (ξ_4f), configuration interaction (α, β and χ) and Judd-Ofelt (Ω₂, Ω₄ and Ω₆) intensity factors. The radiative lifetimes (τ_r) and branching ratios (β) for the fluorescent levels have been reported for all concentrations of Nd³⁺ ion in the above glass systems.

1 illus, 5 tables, 17 ref

012275   Sundaraganesan N;Saleem H;Mohan S (Engineering Physics Dep, Faculty of Engineering & Technology, Annamalai University, Annamalai Nagar-608 002, Email: sundaraganesan_n2003@yahoo.co.in) : FTIR and laser Raman spectra of 2-amino-5-bromobenzoic acid. Indian J Phys 2004, 78(6), 489-94.

The method of normal coordinate analysis is used to evaluate the force constant and the vibrational frequencies of 2-amino-5-bromobenzoic acid. FTIR and laser Raman spectra have been recorded and the assignments of vibrational freqencies have been made. The calculated values of the frequencies fairly agree with the experimental values.

3 illus, 2 tables, 25 ref

012274   Suman;Roshan Lal;Sharma N D;Taneja S P;Gupta A (Dep of Physics, Kurukshetra University, Kurukshetra-136 119, Email: physik@grnth.kuk.ernet.in) : Mossbauer, X-ray and magnetization studies of Ni_0.5Zn_0.5Al_xFe_2-xO₄ system. Indian J pure appl Phys 2005, 43(1), 44-50.

The structural and magnetic properties of the mixed spinel system Ni_0.5Zn_0.5Al_xFe_2-xO₄(x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been investigated by X-ray diffraction, magnetization and Mossbauer measurements. The variation of Mossbauer parameters, lattice parameters and crystalline size of the products formed with variation in the composition of Fe and Al ratio has been studied. The studies confirm the formation of nano-size ferrite particles. It is observed that lattice parameters decrease, with increasing aluminium concentration. A ferromagnetic relaxation occurs when x is increased to 0.6, which is followed by weak paramagnetic transition. With further increase of x to 1.0 the system again shows weak ferromagnetism. The decrease in magnetic hyperfine field with increase in Al concentration has been explained on the basis of super transferred hyperfine field. The variation of the saturation magnetic moment per formula unit measured at 300 K decreases with Al concentration x, suggesting the decrease in ferromagnetic behaviour. These observations indicate the existence of a non-collinear structure in a nano-particles ferrite system. The non-coliinear structure in this system is also verified by Neel's two sub-lattice model.

5 illus, 2 tables, 28 ref

012273   Singh V;Tiwari M;Dhoble S J (Physics Dep, Sadhu Vaswani College, Bairagarh, Bhopal-462 030, Email: vijayjiin@holmail.com) : Luminescence studies of SrS and CaS based phosphors. Indian J pure appl Phys 2005, 43(2), 100-3.

Sulphide based phosphors activated with Bi and Mn ions were prepared by solid-state diffusion method. The emission and excitation spectra of SrS:Bi, SrS:Mn and SrS:Bi, Mn phosphors were recorded at room temperature due to their photoluminescence characterization as well as the energy transfer process. The photoluminescence study of phosphors shows the energy transfer from Bi³⁺ to Mn²⁺. The thermo luminescence study of CaS:Mn and CaS:Bi was also carried out.

4 illus, 2 tables, 28 ref

012272   Singh N K S;Sarma H N K;Kumar S;Arunachalam J (Physics Dep, Manipur University, Canchipur, Imphal-795 003, Email: hnksarma@rediffmail.com) : Studies of some elements in urinary stones by proton induced X-ray emission (PIXE) technique. Indian J Phys 2004, 78(6), 511-3.

The levels of trace elements in urinary stones were investigated by PIXE technique at CCCM, Hyderabad using protons of 2.5 MeV energy. Some of the common elements detected were Ca, Fe, Cu, Zn and Sr and the distribution of the said elements were observed at various region of the stone.

1 illus, 1 table, 17 ref

012271   Singh M;Bhahada K C;Vijay Y K (Physics Dep, University of Rajasthan, Jaipur-302 004) : Variation of optical band gap in obliquely deposited selenium thin films. Indian J pure appl Phys 2005, 43(2), 129-31.

The selenium thin films of obliquely and normal deposited for different thickness were prepared using thermal evaporation method at pressure of 10^-5 torr on to the glass substrate at room temperature. The band gap of thin films with respect to normal to vapour beam direction decreases with angle of deposition, which may be due to small increase in the thickness of the thin films with angle of deposition. The optical band gap has also been observed for different thin films having large variation in thickness. The optical energy band gap of these films decreases with thickness due to quantum size effect.

3 illus, 13 ref

012270   Singh K B (University Physics Dep, B R A Bihar University, Muzaffarpur-842 001) : Photonics. Bhartiya Vaigyanik Evam Audyogik Anusandhan Patrika 2004, 12(2), 341.

Willium Shaukley and his associates John Wardin and Walter Bretain discovered transistor. Due to this invention works are being carried out controlling the microelectrons. In place of electrons quanta of light that is the use of photons has become possible. This new techniques are called photonics. Important role of photonic crystal, photonic band gap, photonic fiber etc. in communication and information field is discussed in the paper.

012269   Singh A K;Mehrotra N K (Physics Dep, Lucknow University, Lucknow-226 007) : NMR spin-lattice relaxation time and activation energy of some substituted phenols. Indian J pure appl Phys 2005, 43(1), 39-43.

The experimental values of NMR spin-lattice relaxation time (T₁) of m-aminophenol, p-aminophenol, o-nitrophenol, resorcinol and p-chlorophenol have been reported. The values of activation energy (ΔE_A) obtained using dielectric relaxation time, have been correlated with calculated values of ΔE_A obtained using Arrhenius equation of NMR spin-lattice relaxation time (T₁) for these compounds. A correlation between the experimental values of T₁ and its calculated values obtained using different equations of dielectric relaxation time (τ) has been established.

4 tables, 14 ref

012268   Shrivastava P K;Singh G N (Physics Dep, Govt New Science College, Rewa-486 001) : Effect of coronal mass ejections on cosmic ray intensity variation. Bhartiya Vaigyanik Evam Audyogik Anusandhan Patrika 2004, 12(2), 340.

Coronal Mass Ejections (CMEs) carry large amount of energy and mass into the interplanetary space. Recently CMEs are known as a main source of geomagnetic disturbances and changes in cosmic ray intensity. In this work, 55 halo CME events are selected for the period of 1996 to 2000 to derive their effects on cosmic ray intensity. It has been investigated that CMEs in association with sudden storm commencement (SSC) are found to be more effective in producing short-term transient decreases in cosmic ray intensity.

012267   Shiva Prasad K;Prasad P S R;Sharma S R (NO, National Geophysical Research Institute, Hyderabad-500 007, Email: psrprasad@ngri.res.in) : Infrared spectroscopic study of phase transitions in natural scolecite. Indian J pure appl Phys 2005, 43(2), 79-82.

In-situ infrared spectroscopic (FTIR) studies are carried out on a naturally occurring scolecite, from Deccan traps, in the temperature range 300-850 K. Five bands are observed at 3589, 3507, 3409, 3327, and 3232 cm^-1 in the (OH) stretching mode region, and three bands at 1665, 1649 and 1591 cm^-1 in the bending mode region indicating a more complex molecular interaction between H₂O and network cations in scolecite. At around 500 K, stretching mode region is replaced with three band structure, and the bending mode region with a band around 1658 cm^-1, indicating partial dehydration in scolecite. At around 720 K complete disappearance of infrared modes due to water molecules indicates total dehydration. X-ray diffraction (XRD) of the sample corroborates the transformation to amorphous phase at higher temperatures.

4 illus, 1 table, 12 ref

012266   Sharma S K;Ojha V N (National Physical Laboratory, , Dr. K S Krishnan Road) : Calibration and dissemination of industrial volt through newly established bank of zener reference standard. Bhartiya Vaigyanik Evam Audyogik Anusandhan Patrika 2004, 12(2), 347.

The conventional 'National Standard' of DC voltage is maintained as a bank of saturated standard cells. Presently it is maintained by newly established automated bank of Zener reference standard. Establishment, properties and traceability have been discussed. Furthermore, dissemination of unit of volt through traceable calibration of Zener reference standard (secondary standard/working standard) their sources of uncertainty in measurements, uncertainty budget and their evaluation based on the ISO 17025 guidelines (Type A and Type B evaluation) have been discussed.

012265   Sharma S;Bajpai R;Chandra B P (Dep of Postgraduate Studies and Research in Physics, Rani Durgavati University, Jabalpur-482 001) : Temperature dependence of the photo-plastic effect in polycarbonate. Indian J pure appl Phys 2005, 43(1), 34-8.

The transparent polycarbonate specimens were illuminated with light of suitable wavelength. The magnitude of the photoplastic effect has been detected and found to be strongly temperature dependent in the range 25-100°C. At low temperature, it shows negative photoplastic effect whereas as high temperature it shows positive photoplastic effect. This observation suggests a way to distinguish among several theories of photoplasticity.

3 illus, 10 ref

012264   Sen V;Panwar N;Singhal S K;Singh B P;Agarwal S K (Superconductivity Div, National Physical Laboratory, New Delhi-110 012) : Effect of external and internal pressures on the insulator-metal transition temperature of the colossal magneto-resistive materials. Bhartiya Vaigyanik Evam Audyogik Anusandhan Patrika 2004, 12(2), 338.

The effect of external pressure (10-40Kbar) and internal pressure was studied on the conduction mechanism of Pr_2/3Ca_1/3MnO₃ colossal magneto-resistive materials. Pr_2/3Ca_1/3MnO₃ is an insulator at low temperatures and on applying external pressure above 10Kbar there is a plateau in resistivity at 115K temperature, giving indications of an insulator-metal transition. Similar indications are also seen at 113K on replacing Mn⁺³ by Fe⁺³ in Pr_2/3Ca_1/3MnO₃. Such a behaviour of Pr_2/3Ca_1/3MnO₃ and Pr_2/3Ca_1/3FeO₃ has been explained on the basis of competition between double exchange and super-exchange mechanisms.

012263   Rostami A;Tajalli H;Sahrai M (Faculty of Electrical Engineering, Tabriz University, Tabriz-51664, Iran, Email: rostami@tabrizu.ac.ir ) : Photon tunneling and light transmission in transparent media. Indian J Phys 2004, 78(6), 479-84.

It is shown that the light transmission in transparent media can be described using photon tunneling phenomenon. Photon tunneling time for the index of refraction barrier can be investigated using Helmholtz wave equation. An analytical expression for the tunneling time of a photon from the index of refraction barrier as well as the transmission coefficient have been reported. It is predicted that the tunneling time depends on the refractive index, the thickness of barrier, and also on the incident wave frequency.

6 illus, 20 ref

012262   Roshan Lal;Sharma N D;Taneja S P;Kailash Chandra (Physics Dep, Kurukshetra University, Kurukshetra-136 119) : Mossbauer, X-ray and magnetization studies of basic volcanic and hyperbasal rocks. Indian J pure appl Phys 2005, 43(2), 119-22.

The ⁵⁷Fe Mossbauer, X-ray diffraction and magnetic susceptibility studies were carried on two samples, basic volcanic (basalt) and hyperbasal (dolerite) rocks, collected from Kundal area of Rajasthan, India to identify iron-bearing minerals. Room temperature Mossbauer parameters of basalt sample show the presence of hematite (Fe₂O₃), aluminium substituted magnesioferrite [Mg(Fe_2-xAl_x)O₄] and illite. Iron is present as both Fe³⁺ and Fe²⁺ in illite. Temperature dependence of magnetic susceptibility measurements shows no transition around 120 K (Verway transition) for both the samples, indicating existence of (Mg, Al) substituted spinel ferrites. These results have been corroborated by X-diffraction and chemical analysis of the samples.

3 illus, 2 tables, 13 ref

012261   Ramamurthy N;Subashini J;Thillaivelavan K (Phys Dep, Annamalai Univ, Annamalai Nagar-608 002) : Fourier transform infrared study of some cess pool environment soils. Indian J envir Prot 2004, 24(4), 251-7.

Infrared spectra of soil samples at different depths from septic tank drainfield leachate were recorded. The observed frequencies in the region 4000-400 cm^-1 have been given in the table along with vibrational assignments and intensities. Probable assignments of the bands were made with respect to the components present in the samples.

4 illus, 1 table, 25 ref

012260   Panwar N;Sen V;Ajay Kumar;Agarwal S K;Pandya D K (Superconductivity Division, National Physical Laboratory, New Delhi-110 012) : Effect of substitution on the metal-insulator transition temperature in colossal magneto-resistive materials. Bhartiya Vaigyanik Evam Audyogik Anusandhan Patrika 2004, 12(2), 337.

The insulator-metal transition temperature T_MI of the colossal magneto-resistive materials with the perovskite structure (ABO₃) depends upon the tolerance factor t and the lattice distortion associated with it. The effect of lattice distortion on T_MI has been reported by tuning the tolerance factor t through substitution of different trivalent and divalent ions at A and B sites of La_2/3Ca_1/3MnO₃ type colossal magneto-resistive materials. The results have been analyzed in terms of a competition between double exchange and super-exchange mechanisms.

012259   Misra U D;Kumar N (Physics Dep, Lucknow University, Lucknow-226 007, Email: udmisra@rediffmail.com) : Systematization of L X-ray satellites II: Lβ₂ and Lγ satellites. Indian J pure appl Phys 2005, 43(2), 83-8.

By the use of the method of iteration, based on Hagstrom's doubly modified Moseley plot, the wavelengths of a large number Lβ₂ and Lγ satellite lines in the atomic number range Z=39 to 80 have been calculated. This has resulted in the removal of anomalies in the measurement of the wavelengths of some of these satellites. A number of experimentally measured satellites have been identified for the first time as a result of our calculations, while in other cases, erroneous identifications by earlier researchers have been corrected.

6 tables, 21 ref

012258   Mishra R;Tiwari M S (Physics & Electronics Dep, Dr. H S Gour Viswavidyalaya, Sagar-470 003, Email: tiwarims@yahoo.co.in) : Particle aspect analysis of the electrostatic ion-cyclotron instability : effects of ion and electron beam and general distribution function. Indian J Phys 2004, 78(6), 495-504.

Dispersion relation, resonant energy transferred, growth rate and marginal stability of the electrostatic ion cyclotron wave (with general loss-cone distribution function in low ft homogeneous plasma) in the presence of upgoing ion beam and downcoming electron beam are discussed by investigating the trajectories of the charged particles. The wave is assumed to propagate obliquely to the static magnetic field. The whole plasma is considered to consist of resonant and non-resonant particles. It is assumed that resonant particles participate in energy exchange with the wave whereas non-resonant particles support the oscillatory motion of the wave. Effects of the steepness of the loss-cone distribution and ion and electron beam velocities on resonant energy transferred and growth rate of the instability are discussed. It is found that the effect of upgoing ion beam is to stabilize the wave and enhance the transverse acceleration of ions whereas the downcoming electron beam acts as a source of free energy for the electrostatic ion-cyclotron wave and enhances the growth rate. Effect of steepness of loss cone is also to enhance the growth rate and decrease the transverse acceleration of ions. The results are interpreted for the space plasma parameters appropriate to the auroral acceleration region.

6 illus, 25 ref

012257   Mandal G;Pradeep Kumar P (Physics Dep, University of Pune, Pune-411 007, Email: ppk@phystcs.unipune.ernet.in) : A laboratory study on the effect of sulfuric acid on charge transfer during ice-graupel collision. Indian J Phys 2004, 78(6), 439-44.

Charge transfer experiments were carried out inside a walk-in cold room to investigate the sign and magnitude of charge that is transferred to the graupel (soft-hail) during collision between ice crystal and graupel. Different concentrations (0%, 25%, and 50%) of aqueous solution of sulfuric acid were used to produce cloud during the experiments. A cloud of supercooled droplets is formed inside the cloud chamber by heating the aqueous solution of sulfuric acid, and the ice crystal formation in the cloud is initiated by momentarily introducing a metal rod dipped in liquid nitrogen into the cloud. It is observed that the magnitude of charge transfer increases with concentration of sulfuric acid in the aqueous solution. If the aqueous solution contains 25% and 50% of sulfuric acid by weight, a coat of dark film is seen on the crystal surface. Due to this film, the crystal boundaries are no longer sharp and well defined like that observed in the crystals produced in pure water cloud. It is suggested that during collision between ice crystal and graupel, this film could be transferred to the graupel resulting in higher values of charge transfer.

6 illus, 37 ref

012256   Lokendra Kumar;Koireng R R;Misra A;Pankaj Kumar;Dhawan S K;Kamalasanan M N;Subhas Chandra (Physics Dep, University of Allahabad, Allahabad, Email: mnkamal@mail.nplindia.ernet.in ) : Blue organic light emitting diode based on lithium tetra-(8-hydroxy-quinolinato) boron complex. Indian J pure appl Phys 2005, 43(1), 56-9.

Blue electro-luminescent materials are essential for the development of full colour display. The synthesis and characterization of blue emitter lithium tetra-(8-hydroxy-quinolinato) boron complex for organic light emitting diode (OLED) applications have been reported. The boron complex was synthesized by the reaction of lithium borohydride with 8-hydroxyquinoline at room temperature and shows absorption cut-off wavelength at 410 nm and bright blue photoluminescence (PL) with a peak wavelength at 485 nm. The electro-luminescence (EL) and I-V characteristics of bilayer OLED are also reported. The results show that boron complexes have a great potential for the blue emitters for OLED applications.

5 illus, 13 ref

012255   Joshi B C;Dhondiyal C C (Physics Dep, Kumaun University, Almora Campus, Almora) : Sensitizing Eu<. Indian J pure appl Phys 2005, 43(1), 21-3.

Enhancement of Eu³⁺ emission by non-radiative energy transfer from Dy³⁺ in zinc phosphate glass has been observed at room temperature. The variation of Dy³⁺ (donor) emission with varying Eu³⁺ concentration (acceptor) and the emission of Eu³⁺ emission in steady-state excitation have been studied. Various parameters necessary for the quantitative study e.g. energy transfer efficiencies, transfer probabilities, critical transfer distances have been computed.

4 illus, 1 table, 11 ref

012254   Harish Chander;Ghosh P K;Shanker V;Haranath D;Sharma P (Luminescent Materials and Devices Group, Electronic Materials Division, National Physical Laboratory, Dr. K S Krishnan Road, New Delhi-110 012) : Research and development of luminescent materials. Bhartiya Vaigyanik Evam Audyogik Anusandhan Patrika 2004, 12(2), 336.

To compete with global market in the field of display devices the development of high quality luminescent materials or phosphors is quite essential. In view of this, Luminescent Materials and Devices Group, NPL has been actively involved in synthesis of inorganic phosphors and fabrication of display devices for more than three decades. The main inorganic fluorescent materials are ZnS and rare-earth oxysulfide based phosphors. While alkaline earth aluminate and titanate are important amongst long decay phosphors. To increase the luminescence efficiency of the phosphors the synthesis of nanoparticles has also been initiated. The R & D activities include modification of various synthesis techniques - Sol-gel process, Combustion process, Chemical synthesis route etc.- to achieve the high efficiency nanoparticle phosphors. The paper describes in brief the synthesis and applications of fluorescent and long decay phosphors.

012253   Gunasekaran S;Abraham L (PG Dep Physics, Pachaiyappa's College, Chennai-600 030, Email: guna_pachai@hotmail.com) : Spectroscopic investigation and vibrational analysis of paraldehyde by FTIR and laser Raman techniques. Indian J Phys 2004, 78(6), 485-8.

Paraldehyde is a trimer of acetaldehyde formed from this under acid catalysis. It falls under the broad classification of the sedative hypnotics used as anti-convulsant in eplepticus and tetanus. The work presents vibrational band analysis on the molecular structure of the compound paraldehyde through infrared and Raman spectral measurements. Normal coordinate analysis has been carried out with a new set of symmetry coordinates to obtain the molecular force field of the system based on C₃V point group symmetry. Potential energy distribution evaluated for all the normal modes of vibration, confirm that the chosen set of vibrational frequencies contribute maximum to the potential energy associated with the normal coordinates of the molecule.

3 illus, 2 tables, 15 ref

012252   Getinet T (Physics Dep, Debub University, Dilla College, P.O. Box 419, Dilla, Ethiopia) : Hall coefficient and coefficient of transverse magneto-resistance of intermediately doped n-type silicon with mixed scattering. Indian J pure appl Phys 2005, 43(2), 104-8.

The explicit expressions for Hall coefficient and coefficient of transverse magneto-resistance in an intermediately doped n-type silicon with mixed scattering of electrons by both ionized impurities as well as acoustic phonons by using the modified density of states function have been derived. These explicit expressions are used to numerically calculate the dimensionless Hall coefficient and coefficient of transverse magneto resistance for different doping concentrations at room temperature. By using the modified density of states function changes the coefficients by as much as 62% and 11% for the normalized Hall coefficient and coefficient of transverse magneto resistance, respectively at room temperature when compared with the corresponding calculations obtained by using the parabolic density of states function.

3 illus, 8 ref

012251   Dutta T;Kabiraj S K;Tarafdar S (Physics Dep, St Xavier's College, Kolkata-700 016) : Three-dimensional viscous fingering patterns in a lifting Hele-Shaw cell: a simulation study. Indian J Phys 2004, 78(6), 455-61.

A hierarchical pattern is formed by viscous fingers in a lifting Hele-Shaw cell. If the defending fluid is visco-plastic, a permanent three-dimensional pattern is formed which is usually approximated as quasi-two-dimensional. The viscous fingers show a hierarchical pattern due to competition between growing fingers in a converging geometry. Using a simple algorithm, a Monte-Carlo simulation is presented which attempts to reproduce the real three-dimensional pattern in rectangular geometry. The finger-length distribution, rate of increase of coverage of the invading fluid, the height profile of the final pattern is calculated and their variation studied with changes in the characteristics of the fluid.

5 illus, 19 ref

012250   Dubey R K;Menon V J;Tripathi D N (Physics Dep, Banaras Hindu University, Varanasi-221 005, Email: jayaram_bhu@yahoo.co.in) : Time dependence of Lippmann-Schwinger states. Indian J pure appl Phys 2005, 43(1), 63-6.

Due to the presence of an infinitesimal parameter ε in the resolvent, the Lippmann-Schwinger states cannot be strict eigenstates of the Hamiltonian, and their time evolution is very non-trivial (in agreement with Fermi's golden rule). In sharp contrast, strict Schrodinger eigenstates cannot make transitions into free channels. Artefacts such as adiabatic switching, wave packets, or infinite time span are not needed in the analysis.

6 ref

012249   Chaturvedi A;Singh M P (Computer Science Dep, Institute of Basic Science, Khandari, Dr. B R A University, Agra-282 002, Email: manu_p_singh@hotmail.com) : Study of bound states in Schrodinger equation of a particle using the Hopfield model of artificial neural network. Indian J Phys 2004, 78(6), 463-9.

In the solution of Schrodinger equation for a particle, confined within one-dimensional infinitely hard boundaries, there are discrete energy states in which the particle can exist. The particle has finite probability of finding itself inside the boundaries for ground, first, second... n-th excited states (i.e. for quantum numbers n = 1, 2, 3,..n). To explore the optimized possibility of finding a particle inside the boundaries for any quantum number, the Stochastic Hopfield Neural Network Model with Mean field Approximation of Simulated Annealing has been used. In this process, the network activation dynamics at a given temperature, reaches the thermal equilibrium position. This equilibrium position is the steady state position of the network that is achieved only if the probability of visiting the global minimum energy states becomes maximum and it refers to the optimized probability of finding the particle inside the boundaries.

1 illus, 13 ref

012248   Chatterjee P (Mathematics Dep, , ) : Large amplitude ion-acoustic solitary waves in a relativistic multi-component plasma. Indian J Phys 2004, 78(6), 505-9.

Exact Sagdeev potential for a multidimensional relativistic multi-component plasma consisting of both positive and negative ions is derived without neglecting electron inertia. It is shown how the negative ion concentration, solitary L.v_λ0/c all play significant role in determining the nature of solitary waves.

3 illus, 20 ref

012247   Chakrabarti S;Chatterjee S;Chattopadhyay U L; Chakravorty J N (NO, Centre for Space Physics, 43, Chalantika, Garia Station Main Road, Kolkata-700 084, Email: space_phys@vsnl.com) : Theoretical study of waves diffracted from asymmetrical profile lamellar gratings. Indian J Phys 2004, 78(6), 471-7.

Diffraction from a microwave asymmetrical lamellar grating (ALG) has been thoroughly investigated. Expressions for intensity, dispersive and resolving power for such a grating have been derived. It is anticipated that such gratings with asymmetrical structure may be used with significant advantage for taking observations in both optical and quasi-optical region. By a suitable choice of geometrical parameters, its applicability may as well be extended to the millimeter and microwave bands which will have significant applications in instruments for astronomical observations and microwave space-communication.

6 illus, 16 ref

012246   Chakrabarti S;Chatterjee S;Chattopadhyay U; Chakravorty J N (Centre for Space Physics, , 43, Chalantika, Garia Station Main Road, Kolkata-700 084, Email: space_phys@vsnl.com) : Studies on microwave lamellar reflection gratings. Indian J Phys 2004, 78(6), 431-7.

The expression was derived for the intensity of the diffracted waves from a lamellar reflection grating. The effects of the elevations and that of the depressions were examined separately and finally derive the resultant intensity was derived. If suitably designed, the applicability of such a grating may be extended to the microwave regions apart from the normal optical and near infra-red region in which it is mostly used- Such a microwave reflection lamellar grating can have significant applications in astronomy and astrophysics. By proper choice of geometrical parameters and modifying its construction with suitable materials, a lamellar grating may be used as a microwave antenna in space communications as well.

7 illus, 18 ref

012245   Aynyas M;Jha P K;Sanyal S P (Physics Dep, S V P G College, Bairagarh, Bhopal-462 030, Email: spsanyal@sancharnet.in) : Lattice dynamics of thorium pnictides and chalcogenides. Indian J pure appl Phys 2005, 43(2), 109-14.

The phonon spectra of thorium pnictides and chalcogenides (ThX) have been analysed using rigid ion and breathing shell models, in view of their structural properties at high pressure. The significance of these two approaches in predicting the dynamical properties of ThX compounds has been discussed and the role of f-electron has been examined. The dominant ionic nature of bonding has been predicted for ThX compound from the large LO-TO phonon splitting at zone centre. The low temperature specific heat for these compounds has been reported.

3 illus, 4 tables, 25 ref

012244   Ananda Kumari R;Chandramani R (Physics Dep, Sree Siddaganga College for Women, Tumkur-572 101, Email: smshashidhara@yahoo.com) : Electrical conductivity and dielectric measurements in Au<. Indian J pure appl Phys 2005, 43(2), 123-8.

Pure potassium dihydrogen orthophosphate (KDP) containing KC1 or NaCl with and without gold doping were grown by slow evaporation technique. All the grown crystals were γ-irradiated using ⁶⁰Co source. Electrical conductivity measurements were carried out perpendicular to the unique direction before and after γ-irradiation. The conductivity of KDP crystals increases with the addition of KCl and NaCl and with gold doping as well as temperature. Computed values of activation energies from the conductivity measurements are given. The dielectric constant and dielectric loss have been measured as a function of frequency. The study confirms the contribution of space charge polarization.

11 illus, 2 tables, 13 ref

012243   Ahsan M R;Uddin M A;Mortuza M G (Physics Dep, University of Rajshahi, Rajshahi 6205, Bangladesh, Email: ranzuphy@yahoo.com) : Infrared study of the effect of P₂O₅ in the structure of lead silicate glasses. Indian J pure appl Phys 2005, 43(2), 89-99.

The infrared spectra of xPbO (1-x-z)SiO₂zP₂O₅ glasses with a PbO:SiO₂ molar ratio of 3:2 and z=0,1,2,5,30,40 and 50 mol% have been examined in the region 4000-400 cm^-1, together with XRD. The structure of PbO-SiO₂ binary glass is significantly different from that of P₂O₅ substituted glasses. The low amount of P₂O₅ containing PbO-SiO₂ glasses results in infrared spectra of the same pattern as 3:2 binary lead silica glass but the maximum peak intensities and positions are different. The spectra of high P₂O5 (30-50 mol%) containing glasses show an increased number of distinct peaks in the low frequency region with a convolution of several broad Gaussians in the high frequency region. All the spectra are base line corrected and deconvoluted to appropriate number of Gaussians. The peaks and peak positions of the Gaussians are assigned to Si-O-Si, Si-O-Pb, Si-O-P, P-O-P, O-P-O, P=O, P-O^- etc. bonds. A variation in the band positions and the relative amounts of bonds with P₂O₅ is also shown. The result indicates that ortho- and pyro-phosphate are formed around 1-5 mol% P₂O₅ containing glasses and meta-phosphate species from the high P₂O5 containing glasses. The ionic character of the phosphate groups P-O^-, PO₄^3- is well revealed by the formation of new band within 1250-900 cm^-1. The incorporation of high contents of P₂O₅ in the materials suggests that P⁵⁺ occupies the network position and forms the linkage Si-O-P in the glasses. This Si-O-P bond may lead to the formation of five and six coordinated silicon in the glass matrix. X-ray diffraction pattern of the base samples, within the detection limit shows that all are homogeneous glasses and these have not shown any evidence of phase separation on optical inspection.

4 illus, 5 tables, 40 ref

011283   Yadav S;Bandyopadhyay A K;Gupta V K;Gupta A C (Pressure & Vacuum Standards, National Physical Laboratory, New Delhi-110 012) : A glimpse of national standards for hydrulic pressure measurements. Bhartiya Vaigyanik Evam Audyogik Anusandhan Patrika 2004, 12(2), 340-1.

Since last two decades, Pressure and Vacuum Standards Group of National Physical Laboratory, New Delhi is actively engaged in the research and developmental activities in pressure metrology, establishment, development, maintenance and upgradation of pressure standards. The paper highlights the glimpse of the national hydraulic pressure standards established and maintained at National Physical Laboratory, New Delhi. The international, bilateral and mutual in-house laboratory traceability of these national standards is also described.

011282   Yadav B C;Shukla R K;Bali L M (Opto-Electronic Research Laboratory, Department of Physics, University of Lucknow, Lucknow-226 007, Email: balchandra_yadav@rediffmail.com) : Sol-gel processed TiO₂ films on U-shaped glass-rods as optical humidity sensor. Indian J pure appl Phys 2005, 43(1), 51-5.

The fabrication and characterization of a thick-film optical humidity sensor based on the semiconducting metal-oxide TiO₂ have been described. The sensor element consists of a thin U-shaped borosil glass-rod having different curvature with a film of TiO₂ deposited on it. The films prepared are dried and annealed at 600°C for two hours, which make them rutile, porous and very sensitive to humidity. Both the ends of the U-shaped glass-rods are coupled to optical fibers. Light from a He-Ne laser is launched in to the sensing element through one of them. Light received from the other fibre is fed into an optical power meter. Variations in the intensity of light with changes in humidity from 5% to 95% have been recorded.

8 illus, 25 ref

011281   Tripathi P S M;Tiwari S N;Mishra K K;Tripathi N (NO, Central Fuel Research Institute, P.O. - F.R.I., Dhanbad-828 108) : Effect of gamma irradiation on the thermal decomposition behaviour and electrical resistivity of some Indian lignite and bituminous coals. Bhartiya Vaigyanik Evam Audyogik Anusandhan Patrika 2004, 12(2), 335.

011280   Suresh Kumar A;Manjubhashini A B (USIC, S V University, Tirupati-517 502) : Spectral properties of different concentrations of Nd<. Indian J pure appl Phys 2005, 43(1), 17-20.

Multi-component oxide glass systems of barium lead borophosphate with 0.01-0.05 mol% of Nd³⁺ ion were prepared using meltquenching technique. The absorption spectral profile of these glasses in the UV-VIS regions was used to determine the spectroscopic characteristic parameters such as Racah (E¹, E², E³), spin orbit (ξ_4f), configuration interaction (α, β and χ) and Judd-Ofelt (Ω₂, Ω₄ and Ω₆) intensity factors. The radiative lifetimes (τ_r) and branching ratios (β) for the fluorescent levels have been reported for all concentrations of Nd³⁺ ion in the above glass systems.

1 illus, 5 tables, 17 ref

011279   Sundaraganesan N;Saleem H;Mohan S (Engineering Physics Dep, Faculty of Engineering & Technology, Annamalai University, Annamalai Nagar-608 002, Email: sundaraganesan_n2003@yahoo.co.in) : FTIR and laser Raman spectra of 2-amino-5-bromobenzoic acid. Indian J Phys 2004, 78(6), 489-94.

The method of normal coordinate analysis is used to evaluate the force constant and the vibrational frequencies of 2-amino-5-bromobenzoic acid. FTIR and laser Raman spectra have been recorded and the assignments of vibrational freqencies have been made. The calculated values of the frequencies fairly agree with the experimental values.

3 illus, 2 tables, 25 ref

011278   Suman;Roshan Lal;Sharma N D;Taneja S P;Gupta A (Dep of Physics, Kurukshetra University, Kurukshetra-136 119, Email: physik@grnth.kuk.ernet.in) : Mossbauer, X-ray and magnetization studies of Ni_0.5Zn_0.5Al_xFe_2-xO₄ system. Indian J pure appl Phys 2005, 43(1), 44-50.

The structural and magnetic properties of the mixed spinel system Ni_0.5Zn_0.5Al_xFe_2-xO₄(x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been investigated by X-ray diffraction, magnetization and Mossbauer measurements. The variation of Mossbauer parameters, lattice parameters and crystalline size of the products formed with variation in the composition of Fe and Al ratio has been studied. The studies confirm the formation of nano-size ferrite particles. It is observed that lattice parameters decrease, with increasing aluminium concentration. A ferromagnetic relaxation occurs when x is increased to 0.6, which is followed by weak paramagnetic transition. With further increase of x to 1.0 the system again shows weak ferromagnetism. The decrease in magnetic hyperfine field with increase in Al concentration has been explained on the basis of super transferred hyperfine field. The variation of the saturation magnetic moment per formula unit measured at 300 K decreases with Al concentration x, suggesting the decrease in ferromagnetic behaviour. These observations indicate the existence of a non-collinear structure in a nano-particles ferrite system. The non-coliinear structure in this system is also verified by Neel's two sub-lattice model.

5 illus, 2 tables, 28 ref

011277   Singh V;Tiwari M;Dhoble S J (Physics Dep, Sadhu Vaswani College, Bairagarh, Bhopal-462 030, Email: vijayjiin@holmail.com) : Luminescence studies of SrS and CaS based phosphors. Indian J pure appl Phys 2005, 43(2), 100-3.

Sulphide based phosphors activated with Bi and Mn ions were prepared by solid-state diffusion method. The emission and excitation spectra of SrS:Bi, SrS:Mn and SrS:Bi, Mn phosphors were recorded at room temperature due to their photoluminescence characterization as well as the energy transfer process. The photoluminescence study of phosphors shows the energy transfer from Bi³⁺ to Mn²⁺. The thermo luminescence study of CaS:Mn and CaS:Bi was also carried out.

4 illus, 2 tables, 28 ref

011276   Singh N K S;Sarma H N K;Kumar S;Arunachalam J (Physics Dep, Manipur University, Canchipur, Imphal-795 003, Email: hnksarma@rediffmail.com) : Studies of some elements in urinary stones by proton induced X-ray emission (PIXE) technique. Indian J Phys 2004, 78(6), 511-3.

The levels of trace elements in urinary stones were investigated by PIXE technique at CCCM, Hyderabad using protons of 2.5 MeV energy. Some of the common elements detected were Ca, Fe, Cu, Zn and Sr and the distribution of the said elements were observed at various region of the stone.

1 illus, 1 table, 17 ref

011275   Singh M;Bhahada K C;Vijay Y K (Physics Dep, University of Rajasthan, Jaipur-302 004) : Variation of optical band gap in obliquely deposited selenium thin films. Indian J pure appl Phys 2005, 43(2), 129-31.

The selenium thin films of obliquely and normal deposited for different thickness were prepared using thermal evaporation method at pressure of 10^-5 torr on to the glass substrate at room temperature. The band gap of thin films with respect to normal to vapour beam direction decreases with angle of deposition, which may be due to small increase in the thickness of the thin films with angle of deposition. The optical band gap has also been observed for different thin films having large variation in thickness. The optical energy band gap of these films decreases with thickness due to quantum size effect.

3 illus, 13 ref