006126   Mahto J P;Mahto S B;Pandit S R (Physics Dep, S.K.M. Univ, Dumka (Santhal Pragana), Jharkhand) : Evaluation of volume plasmon dispersion coefficient of A B group of semiconductors. Bull phy Sci 2009, 5(1), 15-21.

Using the Mishra and Tripathy model Hamiltonian, the plasmon dispersion coefficient of A^IIIB^V group of semiconductors are evaluated by writing plasmon energy equal to E_g √ε₀. E_g is gap parameter and ε ₀ is static dielectric constants. Our evaluated results for α are in good agreement with those of the experimental data.

2 tables, 16 ref

006125   Mahto J P;Mahto S B;Pandit S R (Physics Dep, Govt. Polytechnic Bhagalpur, P.O. + P.S. -Barari, Bhagalpur-812 003) : Theoretical evaluation of optical constants of semiconductors as a function of photon energies. Bull phy Sci 2009, 5(1), 7-13.

Using the method of Kramers-Kronig Analysis (KKA), we have evaluated optical constants of large number of semiconductors taking the real and imaginary part of dielectric constants. Our theoretically evaluated results are in good agreement with that of the other workers and also with the experimental data.

6 tables, 20 ref

006124   Devaraju T C;Alapieti T T;Kaukonen R J; Sudhakara T L (Rajamangala, Saptapur, Haliyal Rd., Dharwad-5800 001, Email: devaraj63@sancharnet.in) : Chemistry of cr-spinels from ultramafic complexes of Western Dharwar cration and its petrogenetic implications. J Geol Soc India 2007, 69(6), 1161-75.

Ultramafic complexes containing chromite-bearing units occur scattered over a large area of the Western Dharwar Craton (WDC). They are broadly separated into two groups; the older complexes, forming a part of the oldest known Sargur Group and occurring as dismembered enclaves within the Peninsular Gneissic Complex, and the younger, forming part of greenstone belt sequence having emplaced in the early stages of basin formation. In this study, chromite-bearing units of the ultramafic complexes of the older group forming the Nuggihalli belt and Rangapura-Shivani complex and the younger group forming the ultramafic complexes of Channagiri, Shankaraghatta and Usgao, have been selectively examined. While Shankaraghatta ultramafite contains sparse disseminations, the other complexes include in addition mm-cm scale bands and lensespods of chromite; commercially workable deposits of chromite are confined only to the Nuggihalli belt. Further, whereas PGE mineralization of possible commercial value is recognized in the Channagiri complex, the Shankaraghatta complex encloses Ni-Au-PGE mineralization. Almost 200 spot analyses of chromite grains occurring in the five different ultramafic complexes of WDC have been obtained. Although it is the most resistant mineral of the rocks, in the intensely altered Channagiri complex it shows deep alteration whereas in the other less altered complexes the alterations are localized to outer zones and margins of the mineral. The least altered Cr-spinel composition (Spl) with X_Mg 0.01-0.656, X_Cr 0.553-0.955 and X_Fe 0.014-0.215 is on the whole in the range of aluminian chromite, but, it shows significant variations from one complex to the other and even within the limits of a single complex, related to primary magmatic processes. An interesting finding is the presence of occasional relics of titanium chromite in the PGE mineralized Channagiri complex.

9 illus, 6 tables, 56 ref

006123   Das N K;Chaudhuri H;Bhandari R K;Ghose D;Sen P;Sinha B (NO, Variable Energy Cyclotron Centre, 1/AF, Bidhannagar Kolkata-700 064) : Purification of helium from natural gas by pressure swing adsorption. Curr Sci 2008, 95(12), 1684-7.

Technique known as pressure swing adsorption (PSA) has been employed in a novel way to concentrate a lean amount of helium present in natural gas through selective physical elimination of N₂, CO₂, CH₄ and C₂⁺ (heavier hydrocarbons) in a stepwise cycle sequence at preset time intervals. The PSA-based helium pilot plant consists of four stages, with each stage composed of three parallel adsorber beds (vessels packed with adsorbents). The plant has been designed and operated for purifying helium to a level of better than 99.0 vol% from a feed natural gas containing helium to the tune of 0.06 vol%. The normal feed pressure range is 4-5 bar (abs). The overall recovery of the pilot plant is around 61%. The features of the PSA system are described here with a detailed description of the operating parameters of the helium pilot plant.

8 illus, 2 tables, 3 ref

006122   Bansal D;Man Mohan;Mittal R K (NO, , 120, Shiv colony, Hari Marg, Tonk Road Jaipur-302 015) : Reactions of hexabutylditin with ligands such as β-diketones and β-Ketoesters. Ultra Scient phys Sci 2008, 20(3), 519-22.

Reactions of hexabutylditin with β- diketones and β-ketoesters in the molar ratio of 1:2 were studied in the medium of anhydrous benzene Complexes of the type R₃Sn-L (where R= -C₄H₉) have been synthesized. All the reactions were not so facile and tin-tin bond to have trigonal bipyramidal geometry.

1 illus, 1 table, 6 ref

006121   Bali R;Awasthi U (NO, Mathematics Harcourt Butler Technolgical Institute Dep, Kanpur-208 002, Email: dr.rekha_bali@yahoo.co.in) : Mathematicla model for oxygen transport in capillary-tissue exchange system in the presence of magnetic field. Ultra Scient phys Sci 2008, 20(3), 593-604.

Mathematical analysis for oxygen transport in capillary and tissue is presented for the case of first order consumption by the tissue in presence of magnetic field. This model consist of a single capillary from which substrate diffuses into a surrounding co-axial tissue. The oxygen transport is appreciably influenced by the application of the magnetic field. Analytical results are obtained by using a series solution method and Picard's type iterative procedure. Obtained the results for oxygen concentration in capillary and tissue region. This description has a complete view on effects of different parameter on the oxygen concentration in both regions.

6 illus, 37 ref

006120   Arafah M R (Physics Dep. Faculty of Sciences, King Abdulaziz Univ, B.O.Box 80203, Jeddah (SAUDI ARABIA), Email: marafah@kau.edu.sa) : Phenomenological analysis of π-Ca elastic scattering. Ultra Scient phys Sci 2008, 20(3), 513-18.

Presents phenomenological analysis of π^{±--Ca elastic scattering at 400, 500 and 672 MeV. The analysis is made within the framework of the diffraction model using parameterized phase shift function. Good agreement with the experimental data is achieved, at all energies.}

6 illus, 1 table, 16 ref

006119   Altaf M;Singh K K;Singh A K;Koul B L;Lalmani (Physics Dep, National Institute of Technology, Hazratbal Srinagar-190 006) : Statistical study of ESD whistlers observed during daytime at a low latitude Indian ground station Jammu (L=1.17). Ultra Scient phys Sci 2008, 20(3), 455-62.

Origin and propagation mechanism of low latitude daytime whistlers are investigated on the basis of the very low frequency (VLF) wave measurements made continuously during day and night hours in North India at our newly setup ground based station Jammu (geomag.lat., 22° 26'N; L=1.17). From the dispersion analysis of the VLF data collected over a time span of about seven years, extremely small dispersion (ESD) whistlers with dispersion varying from 5-10 sec^{1/2 in surprisingly large numbers were found during daytime but only in geomagnetic quiet periods. This feature supports the hypothesis of combined ground ionosphere and field- aligned propagation known as hybrid mode of propagation. The lower cut-off frequencies of these whistlers have been evaluated and majority of these whistlers are found to lie in the low frequency range of ~3-4.4 kHz.}

4 illus, 1 table, 18 ref

005161   Vimalan V;Chandrakumar N (Chemistry Dep, Indian Institute of Technology Madras, Chennai-600 036, Email: nckumar@iitm.ac.in) : General approaches in ensemble quantum computing. J chem Sci 2008, 120(1), 57-69.

It has been developed methodology for NMR quantum computing focusing on enhancing the efficiency of initialization, of logic gate implementation and of readout. General strategy involves the application of rotating frame pulse sequences to prepare pseudopure states and to perform logic operations. Demonstrates experimentally the methodology for both homonuclear and heteronuclear spin ensembles. On model two-spin systems, the initialization time of one of our sequences is three-fourths (in the heteronuclear case) or one-fourth (in the homonuclear case), of the typical pulsed free precession sequences, attaining the same initialization efficiency. Implemented the logical SWAP operation in homonuclear AMX spin systems using selective isotropic mixing, reducing the duration taken to a third compared to the standard re-focused INEPT-type sequence. Introduces the 1D version for readout of the rotating frame SWAP operation, in an attempt to reduce readout time. Further demonstrates the Hadamard mode of 1D SWAP, which offers 2^{N-fold reduction in experiment time for a system with N-working bits, attaining the same sensitivity as the standard 1D version.}

7 illus, 5 tables, 31 ref

005160   Thiyagarajan M;Periasamy C (Mathematics Dep, PSG College of Arts of Science, Coimbatore-641 014, Email: periasamy90@gmail.com) : Thermal boundary layers in MHD flow over a semi-infinite flat plate by a power-law shear. J Energy Heat Mass Transfer 2008, 30(1), 45-55.

The heat transfer characteristics of a hydromagnetic flow driven by a power-law shear over a semi-infinite impermeable flat plate with asymptotic velocity profile in the presence of transverse variable magnetic field is analyzed. The fluid is assumed to be viscous, incompressible and electrically conducting. The effect of viscous dissipation is also considered. Assume that the plate temperature varies as a power of the distance along the plate for the special case of isothermal flat plate. The resulting nonlinear partial differential equations are transformed to nonlinear ordinary differential equations by utilizing similarity transformation and solved numerically by using Runge-Kutta shooting method. These numerical results are shown graphically by means of graphs. The effects of magnetic field and Eckert number are to increase the temperature of the fluid. But the temperature of the fluid decreases with the increase of Prandtl number.

7 illus, 14 ref

005159   Tamil Selvam P;Srinivasan P S S;Vallinayagam E (Mechanical Engineering Dep, SNS College of Technology, Coimbatore-641 035, Email: up_tamil@yahoo.com) : Simple prediction method for laminar film condensation over horizontal intergral-fin copper tubes. J Energy Heat Mass Transfer 2008, 30(3), 311-22.

A simple empirical model, having four non dimensional equations, has been presented for predicting the heat transfer coefficient during film condensation of fluids over horizontal integral-fin copper tubes based on direct correlation of reliable experimental data. The model uses surface tension number, obtained from the numerical study of surface tension drained condensate flow on the fin surface for the unflooded upper portion of the tube and Nusselt's gravity drained model for the flooded lower portion. About 325 experimental data pertaining to four fluids viz., water. R134a, R407c and R123. carried out by 11 investigations, are used in the study. The present model predicts 90 % of experimental data within ± 20%. The effect of fin spacing predicted by the present model is satisfactory and is comparable to other models.

4 illus, 2 tables, 32 ref

005158   Srihari K;Kishan N;Anand Rao J (Mathematics Dep, Mahatma Gandhi Institute of Technology, Gandipet-500 075, Email: kotagirisrihari@yahoo.com) : Hall effect on MHD flow and heat transfer along a porous flat plate with mass transfer and source/sink. J Energy Heat Mass Transfer 2008, 30(4), 361-76.

An analysis of heat source/sink effects on free convective MHD flow and mass transfer of an electrically conducting, viscous incompressible fluid along an infinite vertical porous plate with hall effect has been studied. The problem is solved, numerically by finite difference method for velocity, temperature, concentration field and also the expression for shearing stress is obtained. The effect of Grashof number Gr, Modified Grashof number Gm, Transpiration Cooling λ, Prandtl number Pr, Schmidth number Sc, Magnetic parameter M and Hall Parameter m on the flow field are described in the presence of source/sink parameter S, through graphs and tables.

10 illus, 1 table, 10 ref

005157   Singh N P;Singh A K;Raghav S (Mathematics Dep, V.S.S.D. College, Kanpur-208 002, Email: atulkumarsingh2008@rediffmail.com) : Hydromagnetic convective flow past a horizontal porous plate with periodic free stream velocity and temperature. J Energy Heat Mass Transfer 2008, 30(4), 397-409.

Hydormagnetic convective, laminar flow of an incompressible, electrically conducting, viscous liquid along a horizontal porous plate is studied in the presence of heat source. In the analysis, free stream velocity of the fluid as well as free stream temperature are considered to be periodic in nature. Perturbation technique is used to obtain the solutions for liquid velocity and temperature fields. Expressions for skin-friction and rate of heat transfer at the plate are also derived. The variations in velocity field and temperature distribution are depicted graphically, while variations in skin-friction and rate of heat transfer are numerically computed in terms of amplitude and phase, and presented in tabular form. The results obtained are discussed numerically.

3 illus, 23 ref

005156   Singh N P;Agarwal D C;Singh AK (Applied Sciences and Humanities Dep, Rama Institute of Engineering and Technology, Kanpur-209 217, Email: atulkumarsingh2008@rediffmail.com) : MHD free convection flow with mass transfer between two heated flat vertical plates. J Energy Heat Mass Transfer 2008, 30(4), 377-95.

Free convection and mass transfer in the unsteady flow of an incompressible, electrically conducting, viscous liquid embedded with non-conducting, spherical, solid, small dust particles of equal shape and size between two heated flat vertical plates in the presence of transverse uniform electromagnetic field has been studied in this paper. Laplace transform technique is used to obtain the solution for liquid velocity, particle velocity, temperature field and concentration field. Expressions for the rate of heat and mass transfer are also derived. The effects of various parameters on liquid velocity and particle velocity are numerically discussed with the help of graphs.

2 illus, 33 ref

005155   Singh A K (Mathematics Dep, C.L. Jain (P.G.) College, Firozabad-283 203, Email: aksinghnpsingh@rediffmail.com) : Hydromagnetic mixed convection flow and heat transfer with periodic suction velocity, permeability and heat sink. J Energy Heat Mass Transfer 2008, 30(1), 21-43.

The purpose of the study is to discuss unsteady, laminar, hydromagnetic, convection flow of a viscous incompressible, electrically conducting fluid past a porous vertical plate embedded within highly porous medium when the plate is subjected to a periodic suction velocity, permeability and heat sink. The flow field is considered in the presence of a uniform magnetic field applied normal to the flow. Approximate solutions for velocity and temperature field are obtained using multi-parameter perturbation technique. Expressions for skin-friction and rate of heat transfer are also derived. The results obtained are discussed for various numerical values of the parameters, entered into the equations governing the flow, with help of graphs and tables.

7 illus, 2 tables, 26 ref

005154   Sehrawat A (NO, FC College, Hisar, Haryana) : Reflection and transmission of shearwaves in a self reinforced elastic layer sandwiched between two elastic half-spaces. Arya Bhatta J Math Informatics 2009, 1(1-2), 21-37.

4 illus, 7 ref

005153   Sarkar A;Mahapatra S K;Pal J N;Sarkar A (Mechanical Engineering Dep, National Institute of Technology Rourkela, Rourkela-769 008, Email: swarupkumar_m@yahoo.com) : Effect of eccentricity of natural convection inside a differentially heated horizontal cylindrical annuli. J Energy Heat Mass Transfer 2008, 30(2), 149-66.

Natural convection in a two-dimensional differentially heated cylindrical annulus has been investigated considering the flow to be laminar, incompressible. The fluid properties are considered to be constant over the temperature domain. The vorticity-stream function formulation of the Navier-Stokes equation in cylindrical coordinate system has been employed and FDM is used as the numerical technique. The effect of both vertical eccentricity and horizontal eccentricity of inner cylinder on natural convection has also been examined. The Rayleigh number is varied from 10 to 10^{5. The horizontal eccentricity does not influence the phenomenon much, whereas the vertical eccentricity has substantial influence on the phenomenon.}

6 illus, 5 tables, 16 ref

005152   Ramachandra Prasad V;Bhaskar Reddy N (Mathematics Dep, Madanapalle Institute of Technology and Science, Madanaplle-517 325, Email: rcpmaths@yahoo.com) : Radiation effects on an unsteady MHD convective heat and mass transfer flow past a semi-infinite vertical permeable moving plate embedded in a porous medium. J Energy Heat Mass Transfer 2008, 30(1), 57-78.

An analysis of unsteady, two-dimensional, laminar, boundary-layer flow of a viscous, incompressible, electrically conducting and radiating fluid along a semi-infinite vertical permeable moving plate in the presence of a uniform transverse magnetic field with heat and mass transfer is presented. The Rosseland approximation is used to describe the radiative heat transfer in the limit of optically thick fluids. The plate is assumed to move with a constant velocity in the direction of fluid flow while the free stream velocity is assumed to follow the exponentially increasing small perturbation law. The dimensionless governing equations for this investigation are solved analytically using two-term harmonic and non-harmonic functions. Numerical evaluation of the analytical results is performed and graphical results for velocity, temperature and concentration profiles within the boundary layer and tabulated results for the skin-friction coefficient, Nusselt number and Sherwood number are presented and discussed. It is observed that, when the radiation parameter increases the velocity and temperature decrease in the boundary layer, where as, when thermal and solutal Grashof increases the velocity increases.

10 illus, 5 tables, 19 ref

005151   Petrovic S;Leskovac A;Joksic G (NO, Vinca Institute of Nuclear Sciences, POB 522, 11001, Belgrade, Serbia, Email: sandra@vin.bg.ac.yu) : Radioprotective properties of Gentiana dinarica polyphenols on human lymphocytes in vitro. Curr Sci 2008, 95(8), 1035-41.

The radioprotective properties of polyphenols from the plant Gentiana dinarica Beck. (family Gentianaceae) were evaluated in cultured human peripheral blood lymphocytes exposed to 2 Gy of gamma radiation in vitro. Major constituents of G. dinarica roots include tetraoxygenated xanthones (gentiacaulein and gentia-kochianin), tetraoxygenated xanthone glycosides (nor-swertianin-l-0-primveroside and norswertianin-8-O-primveroside), C-glucoflavones (isoorientin and isoori-entin-4'-O-glycoside) and secoridoids. The incidences of micronuclei, cell proliferation, apoptosis and lipid peroxidation products were examined. Isoorientin, isoorientin-4'-O-glycoside and norswertianin-1-O-prim-veroside showed antioxidant properties, whereas nor-swertianin-8-O-primveroside and gentiacaulein exhibited pro-oxidative effects. Gentiakochianin exhibited cytostatic effects in irradiated lymphocytes. These results contribute to the search for novel radioprotective agents.

1 illus, 1 table, 47 ref

005150   Oommen R;Parameswari R (Physics Dep, Avinashilingam Univ for Women, Coimbatore-641 043, Email: rachell2in@yahoo.co.in) : Fabrication and study on the performance analysis of the wick type solar still. J Energy Heat Mass Transfer 2008, 30(2), 193-208.

The need of the hour in the places where portable -water is scare is solar distillation. The wick type solar still is of academic interest since no commercial or large plant has been installed. The advantage of this type is that due to its very low thermal capacity and exactly parallel and very nearly transparent cover, solar radiation absorption is high thus resulting in higher output In this case, saline water is supplied from the topside of the still to the entire area of the wick remains wet all the time. Solar energy is absorbed by water in the wick which gets evaporated and later condensed on the under side of the glass and finally collected in the condensate channel fixed on the lower side of glass. A single slope wick type solar still of I sqm area was designed, fabricated and oriented with its glass cover with the inclination of 11°. Numerical analysis has been carried out to evaluate the technical feasibility of the still by incorporating the effects of water temperature, cover temperature, heat transfer coefficient etc. Glass temperature, wick temperature, reservoir water temperature insolation, ambient temperature, wind velocity were recorded for regular intervals of time on sunny as well as cloudy days. The distillate yield collected is in the range of 1000 to 1700 ml between 9.00 a.m. to 4.00 p.m. The thermal efficiency of the system is found to be in the range of 10 to 30% for solar insolation of 500 to 800 w/m^{2. The internal and external heat transfer modes are studied. The theoretical results are found to be in agreement with the experimentally observed results.}

11 illus, 5 ref

005149   Olajuwon B I (Mathematics Dep, Agriculture Univ, Abeokuta, Nigeria) : Convective heat and mass transfer in a power law fluid with heat generation and thermal diffusion past a vertical plate. J Energy Heat Mass Transfer 2008, 30(1), 1-19.

Examines the convection heat and mass transfer in a pseudoplastic power law fluid with heat generation and thermal diffusion past a vertical plate. The governing non - linear partial differential equations describing the flow and heat transfer problem are transformed into non - linear ordinary differential equation, using similarity transformation, and the resulting self similar problem is solved numerically using Runge - Kutta shooting method. The problem is studied for power law exponents between 0 and 1. The result is presented as velocity, temperature and concentration profiles. And the numerical values of the skin friction, heat transfer rate, and the mass transfer rate are shown in tabular form. And the analysis of results obtained showed that the heat generation parameter, Schmidt number and the Soret number have significant influence on the heat and mass transfer.

8 tables, 14 ref

005148   Nithiyanandam S;Srinivasan P S S (Mechatronics Engineering Dep, Kongu Engineering College, Perundurai, Erode-638 052, Email: pssmech@yahoo.com) : Energy savings in compressed air supply system using dynamic controller. J Energy Heat Mass Transfer 2008, 30(1), 89-105.

The power required to operate an air compressor depends on the operating pressure bandwidth and the control method used for the compressor. Generally in industries, the maximum operating pressure is set at a higher level due to various reasons with fixed operating pressure bandwidth (PBW). A new attempt has been made to vary the operating pressure bandwidth dynamically based on the consumption of air inside the industry and presented in this paper, for compressors with load/unload type of control. The dynamic control system continuously monitors the consumption of air and reduces the operating pressure bandvidth if the consumption reduces, without affecting other operating conditions. Data taken from the compressed air supply system of a medium sized engineering industry is used for validation. The results prove that energy savings to the extent of 2.26% is possible when pressure bandwidth is dynamically varied instead of having fixed pressure bandwidth.

005147   Muthucumaraswamy R;Kulandaivel T (Information Technology Dep, Sri Venkateswara College of Engineering, Sriperumbudur-602 105, Email: msamy@svce.ac.in) : Radiation effects on moving vertical plate with variable temperature and uniform mass diffusion. J Energy Heat Mass Transfer 2008, 30(1), 79-88.

Thermal radiation effects on unsteady flow past an impulsively started in-finite vertical plate with variable temperature and uniform mass diffusion is studied. The fluid considered here is a gray, absorbing-emitting radiation but a non-scattering medium. The plate temperature is raised linearly with time and the concentration level near the plate is raised to C'_w. The dimensionless governing equations are solved using Laplace-transformation technique. The velocity, temperature and skin-friction are studied for different parameters like radiation parameter, thermal Grashof number, mass Grashof number, Schmidt number and time. It is observed that the velocity increases with decreasing values of the radiation parameter.

6 illus, 1 table, 5 ref

005146   Mhetras S;Ahn H S;Lau S C (Mechanical Engineering Dep, Texas A&M Univ, College Station, Texas 77843-3123, U.S.A., Email: sclau@tamu.edu) : Effect of jet impingement on heat transfer in annular channels with parallel and counter flows. J Energy Heat Mass Transfer 2008, 30(3), 229-50.

This experimental research examines, for turbulent parallel and counter flaws of air through an annular channel, the effects of varying the geometries of the channel and the array of holes along the inner tube on the heat transfer distribution on the inner surface of the outer tube. Each hole array has 5 or 6 inline or staggered circular holes around the circumference of the inner tube at 10 axial stations along the inner tube. Heat transfer experiments are performed for three inner tube diameters, two hole diameters, and Reynolds numbers of 5,000, 12.250 and 30,000, to determine the distribution of the regional average Nusselt numbers along the outer tube, as a result of the jets impinging on its inner surface. Pressure measurements give the overall pressure drops, and the pressure distributions along the inner tube and the annular channel between the inner and outer tubes. The pressure data is needed to determine the mass flow rates of the impinging jets along the inner tube. The jets along the inner tube enhance the regional heat transfer on the inner surface of the outer tube by up to eight times when compared with the heat transfer for fully developed turbulent flow through an annular channel. Heat transfer enhancement is higher for a smaller inner tube and a lower Reynolds number. In the parallel flow case, the heat transfer coefficient on the outer wall of the annular channel is higher near the downstream end of the annular channel, while in the counter flow case, the heat transfer coefficient is higher near the upstream end of the annular channel. For both parallel and counter flows, the heat transfer coefficient is higher in a channel with a larger inner tube. With smaller holes along the inner tube, the heat transfer coefficient along the outer tube is higher and more uniform. Smaller holes, however, cause a higher overall pressure drop across the annular channel, resulting in a lower thermal performance. Increasing the total number of holes lowers the heat transfer, and causes a lower overall pressure drop. The hole mass flow rate increases along the main flow direction in the annular channel for parallel flow, and decreases for counter flow. The variation of the hole mass transfer is smaller for a larger inner tube diameter.

8 illus, 3 tables, 25 ref

005145   Karthikeyan P;Reddy K S (Heat Transfer and Thermal Power Laboratory, Mechanical Engineering Dep, Indian Institute of Technology Madras, Chennai-600 036, Email: ksreddy@iitm.ac.in ) : Absolute steady-state thermal conductivity measurement of insulation materials using square guarded hot plate apparatus. J Energy Heat Mass Transfer 2008, 30(3), 273-86.

An absolute steady-state thermal conductivity measurement of fibrous and non-fibrous insulation materials is carried out using Square Guarded Hot Plate (SGHP) apparatus. The light weight fibrous insulating blankets (25 kg/m^{3 to 190 kg/m3) as well as the heavy insulating slabs (1800 kg/m3 to 2000 kg/m3) of 300 mm x 300 mm size specimens are considered for the thermal conductivity measurement. The thermal conductivities of fibrous insulation blanket and heavy insulating plates are found in the range of 0.0357 to 0.112 ± 0.0028 W/m. K and 0.050 to 0.239 ± 0.0048 W/m.K respectively. The thermal conductivity data obtained from measurements are compared with analytical model for various heavy insulating plates. The results are in good agreement with the analytical model with maximum deviation of ± 2l % for heavy Insulating plates. An uncertainty analysis yields a combined measurement uncertainty of ± 5.75 % at no flow condition. The steady-state square guarded hot plate apparatus can be used effectively to estimate the effective thermal conductivity for all types of insulation materials.}

8 illus, 3 tables, 18 ref

005144   Karmare S V;Tikekar A N (Mechanical Engineering Dep, Government College of Engineering, Karad-411 124, Email: karmaresv@rediffmail.com) : Thermohydraulic performance of solar air heaters with discrete metal rib gris roughness. J Energy Heat Mass Transfer 2008, 30(2), 167-81.

Artificial roughness has been found to enhance the heat transfer from the collector plate to the air in a solar air heater. However, it would result in increase infrictional losses and hence, power required by fan or blower. This paper presents the results of an experimental investigation of roughened solar air heaters with metal rib grits. The effect of roughness on thermal and thermo hydraulic performance is discussed. It also includes the comparison of roughened heaters with that of smooth heaters. The range of variations of system and operating parameters are investigated within the limits, for e/D_h: 0.035 to 0.044, p/e as 17.5 and l/s as 1.72, against variation of Reynolds number from 3600 to 17000. The study shows substantial enhancement in thermal efficiency (10 to 30%), over solar air heaters with smooth collector, due to enhancement in the Nusselt number (50 to 100%). The thermal efficiency enhancement is also accompanied by a considerable increase in the pumping power requirement due to the increase in the friction factor (80 to 250%). At low flow rate, the solar air heater with high relative roughness height yields a better performance. However, at high flow rates the increase in the pumping power is greater than the energy collection for a greater relative roughness height and, hence, the net gain is higher for smaller roughness heights. At still higher flow rate, the smooth duct air heater has better effective efficiency.

12 illus, 1 table, 15 ref

005143   Kandasamy R;Hashim I;Khamis A B;Muhaimin (Centre for Science Studies, University Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor, Malaysia, Email: kandan_kkk@yahoo.co.in) : Thermal stratification and variable viscosity effects on heat transfer along Hiemenz flow over a porous wedge in the presence of heat source. J Energy Heat Mass Transfer 2008, 30(2), 209-27.

The effect of variable viscosity on mixed convection Hiemenz flow over a thermally stratified porous wedge plate has been studied in the presence of heat source. The wall of the wedge is embedded in a uniform Darcian porous medium in order to allow for possible fluid wall suction or injection and has a power-law variation of the wall temperature. An approximate numerical solution for the steady laminar boundary-layer flow over a wall of the wedge in the presence of hear source has been obtained by solving the governing equations using numerical technique. The fluid is assumed to be viscous and incompressible. Numerical calculations are carried out for different values of dimensionless parameters and an analysis of the results obtained shows that the flow field is influenced appreciably by the heat source, thermal stratification, viscosity and suction/injection at wall surface. Effects of these major parameters on the transport behaviors are investigated methodically and typical results are illustrated to reveal the tendency of the solutions. Representative results are presented for the velocity and temperature distributions, as well as the skin friction and rate of heat transfer. Comparisons with previously published works are performed and excellent agreement between the results is obtained. The results are presented graphically and the conclusion is drawn that the flow field and other quantities of physical interest are significantly influenced by these parameters.

11 illus, 35 ref

005142   Jain M;Sharma G C;Singh A (Mathematics Dep, Institute of Basic Science, Dr. B.R. Ambedkar Univ, Khandari, Agra-208 002, Email: mdhujain@sancharnet.in) : Blood flow and diffusion in narrow vessels with mild stenosis under the effect of magnetic field and body force. J Energy Heat Mass Transfer 2008, 30(4), 411-30.

The effects of magnetic field and external body force have been examined on the flow of blood and diffusion in narrow vessels with mild stenosis. We determine the pressure difference, velocity distribution and velocity flow rate of the blood in the capillary. The concentration of undisolved cells with source or sink term is considered in this investigation. The concentration of solute with resistance factor in diffusion is also approximated with the help of non-dimensional analysis. To examine the effects of various other parameters and to validate the analytical results, numerical example is given.

005141   Islam M Q;Ali M;Saha S (Mechanical Engineering Dep, Bangladesh Univ of Engineering and Technology (BUET), Dhaka 1000, Bangladesh, Email: quamrul@me.buet.ac.bd) : Low cost high solidity horizontal axis wind turbine for irrigation in Bangladesh. J Energy Heat Mass Transfer 2008, 30(2), 183-92.

The possibilities of introducing small scale wind powered water pumping in Bangladesh have been assessed based on the available wind data from the Bangladesh Meteorological Department. The large scale wind energy extraction is not feasible in Bangladesh due to low wind speed. There is a potential of small scale wind power pumping in some regions in the country if a proper selection of wind turbine is made. The wind turbine may be useful to drive commercially available No. 6 hand tubewell for irrigating agricultural land. The performance of high solidity horizontal axis wind turbine, made from the discarded domestic ceiling fan blades, is found to be satisfactory. The combined efficiency of wind turbine pump set is found to be about 20% at a wind speed of 2.5 m/s. The Reynolds number (based on wind speed and rotor swept diameter) is in the range of 4.7 x 105 to 1.9 x 106.

8 illus, 4 ref

005140   Haughland D L;Larsen K W;Wheatley M (Biological Sciences Dep, Alberta Univ, Edmonton, Alberta, T6G 2E9, Canada, Email: klarsen@tru.ca) : Importance of radio-telemetry in arboreal squirrel research. Curr Sci 2008, 95(7), 912.

Radio-telemetry allows individual squirrels to be tracked through time and space, providing vital data on individual- and population-level parameters, and minimizing biases inherent in opportunistic observational studies. To emphasize the utility (if not necessity) of telemetry in squirrel research, provide three case studies from our own research involving previously unpublished results on the North American red squirrel (Tamiasciurus hudsonicus) and the northern flying squirrel (Glaucomys sabrinus). We also provide examples of the type of research being conducted worldwide on arboreal squirrels using telemetry. We conclude by discussing advances in telemetry that help minimize the costs and risks of this important technology.

4 illus, 1 table, 46 ref

005139   Ganji D D;Varedi S M;Rahimi M (Mechanical Engineering Dep, Babol Univ of Technology, P.O. Box 484, Babol, Iran, Email: ddg_davood@yahoo.com) : Application of analytical methods to some systems of nonlinear equations arising in fluid flows with variable viscosity. J Energy Heat Mass Transfer 2008, 30(3), 287-310.

Most engineering problems, especially heat transfer and fluid mechanics equations are mostly nonlinear. Variational iteration method (VIM) and homotopy perturbation method (HPM) are useful numerical and analytical methods for solving nonlinear heat transfer and fluid mechanics equations. Perturbation methods depend on a small parameter, which is difficult to be found for real-life nonlinear problems. To overcome this shortcoming, two newly powerful analytical methods are introduced to solve nonlinear heat transfer problems in our work; one is the VIM and the other one is the HPM. The VIM is to construct correction functionals using general Lagrange multipliers identified optimally via the variational theory, and the initial approximations can be freely chosen with unknown constants. The HPM makes a difficult problem much easier to be evaluated. In this research, these methods are used to solve two nonlinear ordinary differential systems for plane couette flow having a variable viscosity.

12 illus, 29 ref

005138   Chaudhuri S;Roy S;Unnikrishnan C S (Fundamental Interactions Laboratory, Gravitation Group, Tata Institute of Fundamental Research, Mumbai-400 005, Email: wrishi@tifr.res.in) : Bose-Einstein condensation in optical traps and in a 1D optical lattice. Curr Sci 2008, 95(8), 1026.

Describes the realization of Bose-Einstein conden-sates (BEC) of ⁸⁷Rb atoms with relatively large number of atoms at high density, in laser-optical traps in our laboratory. Starting from a giant magneto-optical trap containing nearly 10¹⁰ atoms, authors transfer about 5 x 10⁷ atoms into the optical dipole trap formed by crossing two high-power focused CO₂ laser beams. BEC containing about 10⁵ atoms was produced by forced evaporative cooling of the atomic sample in the crossed optical trap down to about 140 nK, in just about a second. The BEC was also produced in a 1D optical lattice formed by the standing wave of a retro-reflected focused CO₂ laser beam, with about 80,000 atoms in the condensate. Effects of mean-field interaction characteristic of BEC were observed in the expansion dynamics of the condensate. We discuss/both the techniques and the innovations that enabled the efficient execution of the multiple steps involved in producing the BEC, starting from a thermal sample of rubidium gas.

11 illus, 35 ref

005137   Chattaraj P K;Sengupta S;Giri S (Chemistry and Centre for Theoretical Studies Dep, Indian Institute of Technology, Kharagpur-721 302, Email: pkc@chem.iitkgp.ernet.in) : Quantum-classical correspondence of a field induced KAM-type transition: a QTM approach. J chem Sci 2008, 120(1), 33-7.

Transition from regular to chaotic behaviour in the dynamics of a classical Henon-Heiles oscillator in the presence of an external field is shown to have a similar quantum signature when studied using the pertaining phase portraits and the associated Kolmogorov-Sinai-Lyapunov entropies obtained through the corresponding Bohmian trajectories.

3 illus, 25 ref

005136   Chakrabarty D;Brahma R (Automobile Engineering Dep, MCKV Institute of Engineering, Liluah-711 204, Email: dipes_chak@yahoo.co.in) : Effect of wall proximity in fluid flow and heat transfer from a triangular prism placed inside a wind tunnel. J Energy Heat Mass Transfer 2008, 30(2), 107-29.

Experimental investigations in fluid flaw and heat transfer have been carried out to study the effect of wall proximity due to flow separation around triangular prisms. Experiments have been carried out for the Reynolds number 4.9 x 10^{4, blockage ratios are 0.1, 0.2, 0.3 and 0.4, different height-ratios and various angles of attack. The static pressure distribution has been measured on all faces of the triangular prisms. The results have been presented in the form of pressure coefficient, drag coefficient for various height-ratios and blockage ratios. The pressure distribution shows positive values on the front face whereas on the rear face negative values of the pressure coefficient have been observed. The positive pressure coefficient for different height-ratios does not vary too much but the negative values of pressure coefficient are higher for all points on the surface as the bluff body approaches towards the upper wall of the wind tunnel. The drag coefficient decreases with the increase in angle of attack as the height-ratio decreases. The minimum value of drag coefficient is observed at an angle of attack nearly 60 for all blockage ratios and Reynolds numbers in case of the triangular prism. The heat transfer experiments have been carried out under constant heat flux condition. Heat transfer coefficient are determined from the measured wall temperature and ambient temperature and presented in the form of Nusselt number. Both local and average Nusselt numbers have been presented for various height- ratios. The variation of local Nusselt number has been shown with non-dimensional distance for different angles of attack and blockage ratios. The variation of average Nusselt number has also been shown with different angles of attack for blockage ratios. The local as well as average Nusselt number decreases as the height-ratio decreases for all non-dimensional distance and angle of attack respectively for triangular prisms. The average Nusselt number for triangular prisms of different blockage ratio varies with the angle of attack. But there is no definite angle of attack at different blockage ratio at which the value of average Nusselt number is either maximum or minimum. Empirical correlations for average Nusselt number have been presented for triangular prism as a function of Reynolds number, Prandtl number and relevant non-dimensional parameters.}

29 illus, 23 ref

005135   Chakrabarti S;Ray S;Sarkar A (Mechanical Engineering Dep, Bengal Engineering and Science Univ, Shibpur, Howrah-711 103, Email: somnathbec@rediffmail.com) : Numerical analysis for sudden expansion with fence in low reynolds number regime. J Energy Heat Mass Transfer 2008, 30(2), 131-48.

The performance simulation of a sudden expansion with fence has been carried out in low Reynolds number regime. The two-dimensional steady differential equations for conservation of mass and momentum has been solved for the Reynolds number ranging from 20 to 100 and distance of fence from throat from 0.2 to 2 for the aspect ratio of 2, fence subtended angle of 10° and fully developed velocity profile at inlet. The effect of each variable on stagnation pressure, average static pressure, and the diffuser efficiency has been studied in detail, and compared with sudden expansion without fence. From the study, it has been revealed that, when the fence is incorporated at the down stream of throat, average stagnation pressure drop becomes less and a sharp increase in average static pressure takes place at the section of fence. For a particular value of Re, variation in location of fence offers no benefit as far as the location of maximum pressure is concerned. In the lower flow Reynolds number, sudden expansion without fence performs better than that of sudden expansion with fence as far as diffuser efficiency is concerned. In the higher flow Reynolds number, the fence should be placed at a distance of around 1 from the throat for the best performance of the diffuser.

6 illus, 3 tables, 11 ref

005134   Bouttout A;Bessaih R (Laboratoire d'Engergetique Appliquee et de Pollution, Genie Mecanique, Mentouri-Constantine Univ, Route d' Ain El. Bey, Constantine 25000, Algeria, Email: Bessaihr@yahoo.fr) : Steady and oscillatory natural convection air cooling of protruding thermal sources mounted in a rectangular enclosure. J Energy Heat Mass Transfer 2008, 30(3), 251-71.

Steady solutions and the onset of instability in natural convection flow due to single and two identical protruding thermal sources, which simulate electronic components mounted in a rectangular enclosure have been studied numerically. The finite volume method has been used to solve the governing equations of two-dimensional unsteady natural convection. The results show that for the case of a single heat source, the flaw becomes oscillatory for the critical Rayleigh numbers, Ra_cr=l.26*10⁴, 1.9X-10⁴ and 1.02 x 10⁵, corresponding to the thermal conductivities of aluminium, silicon and ceramic, respectively. However, for the case of two heat sources, the spacing between them has a significant effect on the fluid flow and heat transfer, and therefore, on the value of the critical Rayleigh number. The Fast Fourier Transform (FFT) has been used to determine the oscillations frequencies. Stability diagram has also been presented in this paper.

18 illus, 1 table, 17 ref

005133   Alam M;Begum D;Yamamoto K (Mathematics Discipline, Khulna Univ, Khulna 9208, Bangladesh) : Flow through a curved duct with large aspect ratio. J Energy Heat Mass Transfer 2008, 30(4), 431-41.

The incompressible viscous steady flow through a curved duct is investigated numerically to examine the combined effects of aspect ratio, γ pressure driven parameter, D_n (Dean number) and curvature, δ (centrifugal force). The flow depends on the Dean number, the dimensionless curvature of the duct and the aspect ratio. The numerical calculations are carried out for D_n =100 and it is covering a wide range of aspect ratio (1.0 ≤ γ ≤8.5). The 2-cell & 8-cell secondary flow patterns are obtained in case of 1.0 ≤ γ ≤ 6.58 and 6.38 ≤ γ ≤ 8.5 respectively.

5 illus, 1 table, 10 ref

005132   Abbas G;Ananthanarayan B;Kriti Ashok;Uma Sankar S (Physics Dep, Indian Institute of Technology, Mumbai-400 076, Email: anant@cts.iisc.ernet.in) : Recent advances in the study of B-meson systems. Curr Sci 2008, 95(7), 827-8.

1 illus, 15 ref

004101   Zannin P H T;Ferreira A M C (Laboratorio de Acustica Ambiental - Industrial e Conforto Acustico - U, Universidade Federal do Parana, Bairro Jardim das Americas, Curitiba, Parana, CEP: 81.531.990, Brasil) : Field measurements of acoustic quality in university classrooms. J scient ind Res 2009, 68(12), 1053-57.

Evaluates acoustic quality of university classrooms in terms of acoustical parameters [external and internal equivalent sound pressure level, reverberation time(RT) and sound insulation of facades]. Only one classroom of BG building exhibited internal equivalent sound pressure level exceeding permissible value of 50 dB(A). RT values, measured in PC Building, were in 6 classrooms in accordance with recommended values from international standards. On the other hand, in BG building, RT measured in all classrooms exceeded established limits. Only completely occupied classrooms in BG building exhibited better acoustic quality in terms of RT as compared to partially occupied and empty classrooms.

004100   Yadav H S;Asthana S N;Subhananda Rao A (NO, High Energy Materials Research Laboratory, Pune-411 021) : Critical shock energy and shock and detonation parameters of an explosive. Def Sci J 2009, 59(4), 436-40.

Deals with the connection between critical shock energy and detonation properties of an explosive. A relation for critical shock energy has been derived in terms of detonation velocity, width of reaction zone, initial density of the explosive, specific heat ratio of detonation products and either constants of linear relation between shock and particle velocity of the explosive or the constants of the Murnaghan.s type of equation of state of the explosive. These relations have been used to calculate the critical shock energy of RDX, HMX, RDX/TNT (60/40) and TNT explosives. The values of critical shock energies obtained in this study are in close agreement with those reported in the literature.

2 illus, 3 tables, 11 ref

004099   Srivastava S K;Avasthi D K (NO, Indian Institute of Technology Kharagpur, Kharagpur-721 302) : Swift heavy ion-induced mixing. Def Sci J 2009, 59(4), 425-35.

Possible swift heavy ion (SHI)-matter interaction processes and their applicability to SHI-induced mixing have been discussed. The assumption that the SHI mixing is a consequence of a transient molten state diffusion has been brought forward. The following experimental evidences have been presented to verify the concepts developed for SHI mixing process: (i) Evidence of high temperature conditions in materials produced by SHI's via the study of SHI mixing in an Fe/Fe⁵⁷/Si system; (ii) Verification of the hypothesis of transient molten state diffusion via a detailed study on Fe/Si system; (iii) The role played by a thermodynamical parameter, viz., interfacial free energy via a SHI mixing study on an Fe/Si multilayer; (iv) Demonstration of the occurrence of the process in an exclusively thermal-spike determined metal/metal system, viz., Fe/Ni multilayer; and (v) synthesis of technologically important SiC phases at room temperature via SHI mixing of C-allotrope/Si multilayers.

14 illus, 1 table, 31 ref

004098   Som T;Sinha O P;Ghatak J;Satpati B;Kanjilal D (NO, Institute of Physics, Bhubaneswar-751 005, Email: tsom@iopb.res.in) : Swift heavy ion beam-induced recrystallisation of buried silicon nitride layer. Def Sci J 2009, 59(4), 351-5.

Studies on MeV heavy ion beam-induced epitaxial crystallisation of a buried silicon nitride layer are reported. Transmission electron micrographs and selected area diffraction patterns have been used to study the recrystallisation of an ion beam-synthesised layer. Complete recrystallisation of the silicon nitride layer having good quality interfaces with the top- and the substrate-Si has been obsorved. Recrystallisation is achieved at significantly lower temperatures of 100 and 200°C for oxygen and silver ions, respectively. The fact that recrystallisation is achieved at the lowest temperature for the oxygen ions is discussed on the basis of energy loss processes.

^iia3 illus, 21 ref

004097   Samadi S;Mahdavi M;Sharifi F;Bihamta M R (Research & Science Branch, Islamic Azad University, Tehran, Iran, Email: zahra.samadi@gmail.com) : Methodology for selecting the best predictor for climate change impact assessment in Karkheh basin, Iran. J envir Sci Engng 2009, 51(4), 249-56.

Prediction of local extreme climatic events, particularly days of heavy rainfall and high temperature which can lead to flash flooding and droughts respectively, is an important study in the present day context. These extreme climatic events can cause devastative effects in agriculture, water infiltration, soil, public hygiene, industry, economy of the country etc. In the future, the rainfall in the region of Karkheh basin (Iran) is expected to be less, but there may be more intense rainfall events. The temperature and rainfall are important parameters for water planning the management. Hence, the climatic change impact studies on different systems such as water resources can lead to more optimal water resource management and planning. On a large scale, General Circulation Models (GCMs) are able to simulate reliably the most important means features of the global climate. The main disadvantage of GCMs is low spatial resolution (2.50). Their results are representative on a large scale, but not on a regional or even a local scale. So these models should be downscaled to study at station scale. For statistical downscaling, 26 predicators are used, but before downscaling the best predictor should be selected. Compares different methods and highlights the steps followed to select the best predictor in Karkheh basin (Iran).

6 illus, 4 tables, 29 ref

004096   Sahoo P K;Kalyan Kamal S S;Jagadeesh Kumar T; Sreedhar B;Singh A K;Srivastava S K (NO, Defence Metallurgical Research Laboratory, Hyderabad-500 058) : Synthesis of silver nanoparticles using facile wet chemical route. Def Sci J 2009, 59(4), 447-55.

Stable aqueous monodispersed silver nanoparticles were synthesised by reducing silver nitrate using various sugars such as glucose, fructose, lactose, and sucrose at 55-60 °C. A mixture of two stabilising agents, polyvinyl pyrrolidone (PVP) of molecular weight (MW 40, 000) and gelatin plays a decisive part in controlling size and shape of superfine silver nanoparticles. Using PVP, better control of particle size was obtained, whereas a mixture of PVP, and gelatin resulted in sea urchin kind of structure. Effects of several processing parameters such as pH, quantities of alkaline solution, reaction time, concentration of stabilising agent, and the metal/dispersant ratio were investigated. The suspensions were stable for at least one week. Silver nanoparticles can be easily collected by centrifugation on mixing with sufficient amount of acetone. Structural characterisation of synthesised silver nanoparticles was carried out by X-ray diffraction (XRD), which shows that the as-synthesised silver nanoparticles are face-centered cubic crystalline. Chemical characterisations of as-synthesized silver nanoparticles were done using inductively-coupled plasma-optical emission spectrometry (ICP-OES) and LECO gas analysers. The optical properties of silver nanoparticles were monitored using UV-Vis spectrophotometer. Role of stabilising agent in protecting the silver nanoparticles was studied using fourier transform infrared spectroscopy (FTIR). Particle size and distribution were characterised using small-angle X-ray scattering (SAXS), zeta particle size analyser (PSA), scanning electron microscopy, and transmission electron microscopy. The average particle size of the as-synthesised silver nanoparticles was 35 nm.

9 illus, 1 table, 54 ref

004095   Rawal D S;Agarwal V R;Sharma H S;Sehgal B K; Muralidharan R (NO, Solid State Physics Laboratory, Delhi-110 054, Email: dsr2002rawal@rediffmail.com) : Dry etching of GaAs to fabricate via-hole grounds in monolithic microwave integrated circuits. Def Sci J 2009, 59(4), 363-70.

Investigates the dry etching of 60 μm dia, 200 μm deep holes for fabrication of through substrate via holes for grounding monolithic microwave integrated circuits (MMICs), on 3-inch dia semiinsulating GaAs wafer using RIE and ICP processes with CFC and non-CFC gas chemistry, respectively. The effect of various process parameters on GaAs etch rate and resultant etch profile was investigated. Two kinds of masks, photoresist and Ni, were used to etch GaAs and performance was compared by investigating effect on etch rate, etch depth, etch profile, and surface morphology. The etch profile, etch depth, and surface morphology of as-etched samples were characterised by scanning electron microscopy. The desired 200 mm deep strawberry profile was obtained at 40 mTorr for both RIE and ICP processes with an etch rate of ~1.3 μm/min and ~4 μm/min respectively. Ni metal mask was used for RIE process due to poor photoresist selectivity, whereas ICP process utilised photoresist as mask. The vias were then metallised by depositing a thin seed layer of Ti/Au (1000 angstrom) using radio frequency sputtering and Au (~5 μm) electroplated to connect the frontside pad and back side ground plane. The typical parasitic inductance offered by these via for RIE and ICP processes was ~76 pH and 83 pH respectively, which is well within the acceptable limits. The developed process was finally integrated to in-house MMIC production line.

14 illus, 1 table, 12 ref

004094   Raghunathan V A (NO, Raman Research Institute, Bangalore-560 080, Email: varnathan@yahoo.com) : Mesh phases of surfactant-water systems. J Indian Inst Sci 2008, 88(2), 197-210.

Mesh phases are a class of intermediate phases found in many surfactant systems, which provide a topological link between the hexagonal phase made up of cylindrical micelles and the lamellar phase made up of planar bilayers. Gives a brief review of the structures of these phases and also of different surfactant systems where they occur. The emphasis will be on a class of mixed surfactant systems in which mesh phases have been shown to occur recently. The influence of various structural parameters of the surfactant on the structure and stability of these phases is also discussed.

18 illus, 29 ref

004093   Paramanik D;Majumder S;Sahoo S R;Varma S (NO, Institute of Physics, Bhubanewsar-751 005) : Nano pattern formation and surface modifications by ion irradiation. Def Sci J 2009, 59(4), 413-24.

Ion Irradiation is a technologically important technique to modify the surfaces. Investigated the patterning of InP(111) surfaces by low energy (3 keV) as well as high energy (1.5 Mev) ion beams. After low energy ion irradiation, surfaces exhibit well defined nano dots which ripen at initial stages but exhibit fragmentations at high fluences. The surface rms, at both the energies, displays a similar behaviour of initially increasing with increasing fluences but decreasing for higher fluences. The studies show some common features at these low and high energies, like the smoothening of surface beyond the a/c transition.

14 illus, 1 table, 48 ref

004092   Nambissan P M G (NO, Saha Institute of Physics, 1/AF Bidhannagar, Kolkata-700 064, Email: pmg.nambissan@saha.ac.in) : Characterisation of ion implantation-induced defects in certain technologically important materials by positron annihilation. Def Sci J 2009, 59(4), 329-41.

Application of positron annihilation spectroscopy for the studies of defects produced by different types of charged particles and ions in a variety of materials is discussed with specific examples. The ability to detect and quantify the information through the characteristic parameters of the annihilation radiation in a totally non-destructive method has made the fundamental process of electron-positron annihilation a powerful spectroscopic probe for investigating the structure and properties of materials. Ion implantation produces defects in the structure of solids and the latter can be recovered from the defects by annealing at high temperatures. Here the annealing is done in sequential steps so that the different stages of evolution of defects and their interaction with impurity atoms can be studied systematically. Defects produced by irradiation by particles like protons, alpha, boron and neon ions in materials ranging from simple metals to binary alloys are discussed. A detailed evaluation of the positron lifetimes in terms of the popular positron trapping models is also presented. Further as a special case, the method of extraction of values of several useful physical parameters of inert gas bubbles inside a metal matrix is explained with the help of a model analysis.

^iia15 illus, 1 table, 40 ref

004091   Jagtap U;Sharma A K (NO, Dhanaji Nana College, Faizpur-425 503, Email: jagtapuday@rediffmail.com) : Some characteristics of F-region plasma depletions during geo magnetic quiet condition using OI 630.0 nm nightglow emissions at Kolhapur (16.8°N; 74.2°E). Asian J chem envir Res 2008, 1(1), 27-30.

Regular Night Airglow observations were made from Kolhapur, a low latitude station (16.8°N; 74.2°E) in India on clear moonless nights using tilting photometers. The photometers are portable and can be directed to any desired point in the sky (viz., along the Zenith, 30° East, and 30° North of zenith direction). For the study only two photometer were operative (Zenith, and 30° North). During this study, percentage depth, width of depletion and medidional plasma speed are computed. It was found that, (a) width of bubble varied from 315 to 360 km, and (b) the meridional plasma drift speeds ranging from 73 to 161 m s^-1. It was also found that, at night the meridional winds were equatowards and abated at midnight. Authors compared our data obtained using tilting photometer with the ionospheric data (h;F) and scintillation data. The ionospheric data were used from Ahmedabad (23.02°N, 72.6°E) station to know ionospheric conditions during the period of airglow observations. The scintillation data was obtained from Kolhapur.

13 ref

004090   Dhaul A;Sharma S K;Sharma R K;Kapoor A K (NO, Solid State Physics Laboratory, Lucknow Road, Delhi-110 054) : Characterisation of semiconductor materials/device structures usign SIMS. Def Sci J 2009, 59(4), 342-50.

Secondary ion mass spectrometry (SIMS) is an analytical technique that can be used to characterise the surface and near-surface region of solids. The instrument operation and data analysis have been discussed to obtain meaningful results. Discusses the technique of sequential sputtering to elucidate the thickness of individual layers in a multilayer structure. The application of the technique for failure analysis, standard generation and interface studies have been discussed in detail taking examples of multilayer structures of compound semiconductors being developed at SSPL.

^iia15 illus, 3 tables, 24 ref