015964   Gandhi D C (Physics Dep, A.M. College, At & P.O. Jhalda, Purulia-723 202) : Magnetic dipole radiative decay of mesons in potential models. Indian J Theor Phys 2006, 54(1), 43-58.

Studies the magnetic dipole transitions of the low-lying mesons in potential models with confining potential =r^β for β = 0.1, 0.3, 1, 2. This sytematic study not only accounts for the observed decay widths and predicts some others but also helps us to comment on-some important aspects of quark-antiquark potentials.

3 tables, 36 ref

015963   Gagan Kumar;Kanthwal M;Chauhan B S;Singh M (Physics Dep, Himachal Pradesh University, Summer-Hill, Shimla-171 005) : Cation distribution in mixed Mg-Mn ferrite systems from X-ray diffraction technique and saturation magnetization. Indian J pure appl Phys 2006, 44(12), 930-4.

Ferrites with general formula Mg0.9 Mn0.1 Fe_2-x In_x O₄, Mg_0.9 Mn_0.1 Fe_2-y Al_y O₄ and Mg_0.9 Mn_0.1 Al_0.3 Co_z Fe_1.7-z O₄ (where x, y = 0.0, 0.1, 0.3, 0.5 and z = 0.3, 0.5, 0.7) were prepared by citrate precursor technique and studied by means of X-ray diffraction and saturation magnetization. The X-ray analysis confirmed the single-phase formation of the sample. The cation distribution is inferred from the results of X-ray diffraction and magnetization measurements.

3 illus, 1 table, 18 ref

015962   Ananthanarayan B;Gautham C;Mavalankar A; Shivaraj K;Uma Sankar S;Upadhyay A (Centre for High Energy Physics, Indian Institute of Science, Bangalore-560 012) : Progress in determination of neutrino oscillation parameters. Curr Sci 2006, 91(7), 864-7.

30 ref

014746   Zhu D;Luo O;Zhang T;Cheg H;Zeng S;Ulyanov S (The Key Laboratory of Biomedical Photonics of Ministry of Education, Huazhong Univ of Science and Technology, Wuhan, 430074, P.R. China) : Laser speckle microscopic system for monitoring of dynamic blood perfusion. Asian J Phys 2006, 15(1), 67-75.

Measurement of blood perfusion has been playing an important role in the field of clinical medicine, but it has been a problem for monitoring blood perfusion in the clinical practices like disease diagnostics, drug delivery, and tumor hyperthermia. A new apparatus for non-contacting and non-disturbance, which combined laser speckle microscopic technique with video camera, was developed. Dynamic blood flow rate was measured with laser speckle microscopy by using the techniques of zero-crossings, and corresponding blood vessel diameter was recorded with video camera. Based on the measurements of blood flow rate and vessel diameter, the blood perfusion could be deduced. This apparatus was applicable for monitoring relative change in blood perfusion of rat mesentery during cooling or heating at different constant temperature. When the temperature was lower or higher than core temperature, the blood perfusion decreased or increased at initial 20 minutes, and tended to be in equilibrium, whereas the blood perfusion was almost steady. Moreover, the increment of blood perfusion in equilibrium is linear with temperature, which is consistent with the conclusion from thermal physics method. The results showed that blood flow rate could not provide reliable information for dynamics of blood perfusion unless the dynamics of vessel diameter is considered. The comparative research proved that it is valid to investigate kinetics of blood perfusion with laser speckle microscopic monitoring technique, which could provide a new method for measuring real time dynamic blood perfusion under exterior factors.

6 illus, 25 ref

014745   Zheng Y;Yingpeng L;Jun C (Department of Precision Instruments, Tsinghua University, Beijing, China) : Measurement of novel micro bulk defects in semiconductive materials based on mie scatter. Indian J pure appl Phys 2007, 45(4), 372-6.

Introduces a new micro bulk defects measurement method in semiconductive materials, which scales the defects by analyzing scattering light distribute based on Generalized Lorenz and Mie Theory (GLMT). A method named character recognition and pick up two characters as defect criterions have been presented. Moreover, a set of experimental apparatus is built to prove the detect method and defect criterions. The micro bulk defects in semiconductive materials have been detected experimentally.

5 illus, 4 tables, 14 ref

014744   Zhang W;Xue C;Xiong J;Xie B;Wei T;Chen Y (Kay Lab of Instrumentation Science & Dynamic Measurement of Ministry, North University of China, Taiyuan, Shanxi 030051, China, Email: wdzhang@nuc.edu.cn) : Piezoresistive effects of resonant tunneling structure for application in micro-sensors. Indian J pure appl Phys 2007, 45(4), 294-8.

Piezoresistive properties of resonant tunneling structure made of undoped InGaAs/AlAs double-barrier quantum layers have been experimentally investigated, and the resonant tunneling structure was grown by molecular beam epitaxy (MBE) on semi-insulation (001)-oriented GaAs substrate. We found that the piezoresistivity of such quantum layers is about one order higher than that of the commonly used silicon structures. Micro accelerometers based on InGaAs/AlAs double-barrier resonant tunneling structures have also been designed and fabricated by control hole technique.

9 illus, 4 ref

014743   Yang X;Zhou Z;Wu Y;Xiao M;Luo Q;Shao C (Department of Precision Instruments & Mechanology, MEMS Lab, Tsinghua University, P R China, Email: yangxing@mail.tsinghua.edu.cn) : Measurement and simulation of carbon nanotube's piezoresistance property by a micro/nano combined structure. Indian J pure appl Phys 2007, 45(4), 282-6.

The status of carbon nanotube's electromechanical properties was reviewed. The relationships among the carbon nanotube's resistance, gauge factor and the rates of change of the band gaps with strain (dE_g/dε) were analyzed and simulated. Then, a micro/nano combined device and method for measuring the piezoresistance property of carbon nanotube were proposed. The device is consisted of a silicon chip and a printed circuit board which is used for loading and leading wire. The microelectrodes were fabricated on the silicon chip by FIB and a CVD-growth single-wall carbon nanotube was connected with the microelectrodes. The voltage-current characteristic of the carbon nanotube was measured using the proposed device. The relationship between the current and the voltage is basically linear, which demonstrates that the carbon nanotube is metallic. The experimental results show that the micro/nano combined device can be used for measuring the piezoresistance of carbon nanotube in our future work.

6 illus, 9 ref

014742   Yadav B S;Tyagi S K;Seema (Molecular Spectroscopy and Physics Laboratory, D N (PG) College, Meerut-250 002, Email: sktyagi12@rediffmail.com) : Study of vibrational spectra of 4-methyl-3nitrobenzaldehyde. Indian J pure appl Phys 2006, 44(9), 644-8.

The vibrational (infrared and Raman) spectra of 4-methyl-3-nitrobenzeldehyde have been reported. The assignments of fundamentals are proposed and discussed by assuming the molecular under C_s point group symmetry.

4 illus, 1 table, 24 ref

014741   Yadav B C;Srivastava A;Shukla R K;Dubey G C (Physics Dep, Opto Electronic Research Laboratory, Lucknow Univ, Lucknow-226 007) : Opto-electronic humidity sensor with incident light in the form of a conical beam. Indian J pure appl Phys 2006, 44(9), 694-9.

An extensive experimental investigation of TiO₂ film has been carried out. TiO₂ films have been deposited on a prism base by using sol-gel spin process. As the humidity increases in the environment where such films are placed, physisorption and chemisorption of water take place through the pores of films. This leads to a corresponding modulation in the intensity of reflected light. Thus, relative humidity is estimated directly in terms of modulation in the intensity of light observed on a digital power meter. Surface morphology of TiO₂ films has also been studied.

11 illus, 34 ref

014740   Wu Y;Zhou Z;Yang X;Xiao M;Luo Q;Zhang J;Zhang Y Y;Yao Y (State Key Lab of Precision Measurement Technology and Instrumentation, Tsinghua University, Beijing, 100084, P R China) : Fabrication of single-walled carbon-nanotube with metallic electrodes. Indian J pure appl Phys 2007, 45(4), 368-71.

Aligned array of single-walled carbon nanotubes on a substrate is synthesized by chemical vapour deposition of methane. The combined synthesis and FIB technique presented here demonstrated the nanotube devices with metallic electrodes. Sample characterization was carried out with SEM pictures and I-V curves, which show that the nanotube with metallic electrodes may be widely used in both basic research and applications.

3 illus, 5 ref

014739   Vladimirov A P;Kilunova N V;Michurov A V; Yakovleva S V (NO, Institute of Engineering Science of Ural dpt of RAS, Yekaterinburg, Russia, 620219) : Speckle dynamics produced by lecithin-water sol-gel transition. Asian J Phys 2006, 15(1), 93-100.

The goal of this work is a designing the measuring equipment and developing the procedure of parameters registration, characterizing the speckle dynamics. At the base of the experiments the following conclusions can be made: (a) an optical setting was created, allowing to visualize and register the speckle dynamics in the image area of transparent cuvette, filled with lecithin- water emulsion; (b) a strategy of parameters registration was developed, characterizing the speckle dynamics, including the film recording, forming space- temporal pictures, carrying out a correlation analysis, spectral analysis, calculating the frequency of speckle winking, deducing a mean and root-mean- square deviation of the optical signal for the researching system. With a help of the technique it was discovered, that the local maximum of the frequency speckle winking takes place at the solution- gel border, the maximum of the temporal bandwidth is reached before, and the maximum of the standard signal deviation- after the lipid solution is transferred into gel.

8 illus, 2 ref

014738   Vishwakarma R K;Ansari J A;Meshram M K (Department of Electronics Engineering, Insitute of Technology, Banaras Hindu University, Varanasi-221 005) : Equilateral traingular microstrip antenna for circular polarization dual-band operation. Indian J Radio Space Phys 2006, 35(4), 293-6.

Experimental investigations were conducted on the equilateral triangular microstrip antenna to examine the radiation characteristic with two-layer triangular patch antenna. The two-layer triangular patch at both the frequencies 3.0 and 3.5 GHz radiate maximum power, VSWR, return loss, etc. which depended heavily on two-layer triangular microstrip patch antenna. It is shown to be possible to design two-layer equilateral triangular patch antenna for dual-band operation with reasonably good circular polarization.

5 illus, 9 ref

014737   Vinod Kumar;Pant R P;Halder S K;Yadav M S (X-ray Section, National Physical Laboratory, Dr K S Krishnan Marg, New Delhi-110 012, Email: rppant@mail.nplindia.ernet.in) : Development of ferrofluid and its possible applications in MEMS. Indian J pure appl Phys 2007, 45(4), 406-10.

In micro-fluidic devices, fluid control plays a crucial role in its operation. The input and output in the device must pass through control surface. Synthesized nano magnetic fluid is characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM) techniques for its potential applications in MEMS devices as gas pressure valve. Operation of gas pressure valve was monitored at varying electromagnetic actuation level.

6 illus, 1 table, 11 ref

014736   Vadivel Murugan A;Gaikwad A B;Samuels V;Ravi V (Materials Chemistry Div, Centre for Materials Characterization, National Chemical Laboratory, Pune-411 008, Email: r.venkat@ncl.res.in.) : Coprecipitation technique to prepare Sr_0.5Ba_0.5Nb₂O₆. Bull Mater Sci 2006, 29(3), 221-3.

An aqueous mixture of ammonium oxalate and ammonium hydroxide was used to coprecipitate barium and strontium ions as oxalates and niobium ions as hydroxide under basic conditions. This precursor on calcining at 750°C yielded Sr_0.5Ba_0.5Nb₂O₆ phase. This is a much lower temperature than that prepared by traditional solid state method (1000°C) as reported for the formation of Sr_0.5Ba_0.5Nb₂O₆ (SBN). Transmission electron microscopic (TEM) investigations revealed that the average particle size was 80 nm for the calcined powders. The room temperature dielectric constant at 1 kHz was found to be 1100. The ferroelectric hysteresis loop parameters of these samples were also studied.

3 illus, 8 ref

014735   Upadhyay T C (Physics Dep, HNB Garhwal University, Srinagar, Garhwal-246 174, Email: trilokphys@yahoo.co.in) : Temperature dependence of dielectric constant and loss tangent in layered antiferroelectric squaric acid crystal. Indian J pure appl Phys 2006, 45(2), 157-62.

A model of pseudospin for layer type 1 and type 2 for squaric acid crystal proposed by Li and Qin, Ferroelectrics, 82 (1988) 69, has been modified to include pseudospin-phonon interaction and cubic and quartic phonon anharmonic interactions. With the help of double-time temperature dependent Green's function method and modified Hamiltonian, expressions for antiferroelectric soft mode frequency, dielectric constant, loss and transition temperature have been evaluated. By fitting model values of physical quantities in the theoretical expressions, temperature dependence of soft mode, dielectric constant and loss has been calculated in the vicinity of transition temperature. Theoretical results have been compared with experimental results of Muser, Maier et al. and Samara and Semmingsen, which show a good agreement.

3 illus, 3 tables, 21 ref

014734   Tyagi S K;Wang S;Kaushik S C (Building Services Engineering Dep, The Hong Kong Polytechnic Univ, Hung Hom, Kowloon, Hong Kong) : Irreversible modified complex brayton cycle under maximum economic condition. Indian J pure appl Phys 2006, 44(8), 592-601.

An irreversible complex Brayton cycle under maximum economic conditions has been investigated. The economic function has been optimized with respect to the cycle temperatures, reheat and intercooling pressure ratios for a typical set of operating conditions. It is found that there are optimal values of the intercooling, reheat and cycle pressure ratios at which the cycle attains the maximum objective function, maximum power and maximum efficiency. The maximum economic point, maximum power point and the maximum efficiency point exist but the economic function corresponding to the maximum power and maximum efficiency is found to be lower than that can be attained and vice-versa. The optimal values of different parameters corresponding to the maximum economic function are different from those corresponding to the maximum efficiency and maximum power for the same set of operating conditions. Again, all the performance parameters further enhance as the heat capacitance rates of the external reservoirs and increased, while it is found to be reverse in the case of the working fluid heat capacitance rate and the inlet temperature of the conversing combustion chamber (CCC). The objective function and efficiency are found to be the decreasing functions of the reheat pressure ratio for lower values of CCC inlet temperature while there are optimal values of the reheat pressure ratio for higher values of the inlet temperature of the CCC.

6 illus, 1 table, 28 ref

014733   Tewari S P;Silotia P;Saxena A;Gupta L K (Physics & Astrophysics Dep, University of Delhi, Delhi-110 007) : Effect of three-body interaction in strongly interacting Bose-Einstein condensate in isotropic and highly anisotropic magnetic trap. Indian J pure appl Phys 2006, 45(2), 173-9.

Ground state properties of Bose-Einstein condensate of 20000 ²³Na atoms confined in isotropic and highly anisotropic magnetic traps in the presence of three-body interaction, in addition to the two-body and hard-core interactions, have been theoretically studied by solving modified highly non-linear Gross-Pitaevskii-Ginzburg (GPG) equation. There is increasingly significant change in the chemical potential, total and differential energies per particle as the aspect ratio, λ, is increased from 0.1 to 1.0, with respect to the corresponding values when only two-body and hard-core interactions are considered. The condensate order parameter changes drastically and becomes quasi 1-dimensional, as λ is varied from 1 to 0.1.

4 illus, 29 ref

014732   Sutar D;Aswal D K;Gupta S K;Yakhmi J V (Technical Physics & Prototype Engineering Division, Bhabha Atomic Research Center, Trombay, Mumbai-400 085) : Electrochemical actuator from conductive electroactive polymer polypyrrole deposited on gold. Indian J pure appl Phys 2007, 45(4), 354-7.

Electrochemical bilayer actuators were fabricated from conductive electroactive polymer polypyrrole deposited by electrochemical polymerization. Films of polypyrrole doped with dodecylbenzene sulphonate (PPy-DBS) and with gold coating on one side were prepared by galvanostatic electrochemical polymerization of pyrrole. Polystyrene sheet (used for over-head-projector) with thermally deposited gold film, was used as working electrode. The strong interaction of pyrrole with gold was made use of to get a freestanding polypyrrole film with gold coating on one side (PPy-DBS/Au). Bilayer actuators, were fabricated from these freestanding films and tested in 1 M LiClO₄ solution. The actuator showed bending of up to 90° on both sides on electrochemical reduction/oxidation under an applied potential of 2-3 V. The applied voltage determined the response time, which was 2 to 3 s. The actuator action was also observed with low frequency ac signal.

4 illus, 11 ref

014731   Sunandana C S;Bharathi Mohan D (School of Physics, Hyderabad Univ, Hyderabad-500 046, Email: csssp@uohyd.ernet.in) : EPR probes ion dynamics of superionic conductors. Indian J pure appl Phys 2006, 44(9), 637-43.

Superionic conductors possess large concentrations of monovalent mobile ions such as Ag⁺ in AgI and Li⁺ in LiClO₄:PEG that travel through diffusion even larger number of defect sites leading to ionic conductivities of the order of 1S/cm around ambient temperature often through structural phase transitions. Any mobile ion complex that is part of a network or unit cell becoming paramagnetic through electron/hole capture, can serve as a probe for ion dynamics and phase transitions. This paper identifies the basic issues of superionic conductors from EPR standpoint and demonstrates through five case studies.

9 illus, 1 table, 16 ref

014730   Srivastava R;Dwivedee D K;Khanna K N (Physics Dep, V S S D College, Kanpur) : Thermodynamic properties of repulsive hard-core yukawa fluid. Indian J pure appl Phys 2006, 44(8), 612-15.

A simple analytical expression of the mean spherical solution (Mean spherical approximation - high temperature expansion) to the Ornstien-Zernike equation for repulsive hard core Yukawa fluid is examined. The thermodynamic and structural properties of purely repulsive hard-core Yukawa particles in the fluid state are determined by employing this model and compared with simulation data. The results show that the present model illustrates the remarkable improvement of internal energy per particle over existing theoretical values.

2 illus, 2 tables, 23 ref

014729   Sravana Kumar D;Krishna Rao D (Department of Physics, Acharya Nagarjuna University, Nagarjunanagar-522 510, Email: gurukripadsk@yahoo.com) : Study of molecular interactions and ultrasonic velocity in mixtures of some alkanols with aqueous propylene glycol. Indian J pure appl Phys 2007, 45(3), 210-20.

Ultrasonic velocity, density and viscosity are experimentally determined in the mixtures of methanol/ethanol with aqueous propylene glycol (4.5m and 1.5m) over entire range of composition at 303.15K. Several acoustic and thermodynamic parameters such as excess viscosity, excess adiabatic compressibility, excess free volume, excess molar volume, excess enthalpy, excess free length, viscous relaxation time have been calculated to study nature and extent of molecular interactions in these mixtures. Ultrasonic velocities theoretically evaluated using Nomoto's relation, Van Dael and Vangeel's ideal mixing relation, impedance relation, Jacobson's equation, Rao's specific sound velocity relation and Junjie's equation are compared with experimental values to check applicability of these equations to the systems studied. The departure of experimental values of ultrasonic velocities from theoretical values is further analyzed to investigate molecular interactions. Two types of polynomial equations are fitted to experimental values of ultrasonic velocities. These polynomial representations of sound velocities have extremely small deviations from experimental values.

16 illus, 7 tables, 23 ref

014728   Singh V;Tripathi B V;Joshi D C (Physics Dep, H N B Garhwal Univ, Srinagar, Garhwal-246 174) : Stability analysis of dyon solutions SU(3) SU(3) in gauge theory. Indian J pure appl Phys 2006, 44(8), 567-75.

The stability of the dyon solutions obtained by using a Cabibbo Ferrari type non-abelian field tensor has been analyzed and it has been found that they obey the criterion of stability of having a finite energy with a saturated lower bound with conserved electric and magnetic charges.

16 ref

014727   Singh G;Singh M;Sandhu B S;Singh B (Physics Dep, Punjab University, Patiala-147 002) : Experimental investigation of saturation depth of 0.662 MeV gamma rays in copper. Indian J pure appl Phys 2006, 45(2), 111-15.

The effect of target thickness on 0.662 MeV multiply Compton scattered gamma photon has been studied experimentally. An intense collimated beam, obtained from 6-Ci¹³⁷Cs source, is allowed to impinge on a rectangular copper target of varying thickness and the scattered photons are detected by a properly shielded NaI(T1) scintillation detector, having dimensions 51ϕ mmx51 mm, placed at 90° to the incident beam. The subtraction of events under the analytically reconstructed full energy peak from the events recorded under the observed inelastic peak results in multiply scattered events having energy same as in single scattering. The target thickness at which the number of multiply scattered events saturates has also been determined. The signal-to-noise ratio is found to be decreasing with increasing target thickness. Monte Carlo calculation supports the present experimental results.

6 illus, 13 ref

014726   Singh G S;Bajpai R P (Advanced Optical Processing Division, Central Scientific Instruments Organization, Sector 30, Chandigarh-160 030) : Design consideration of two components mechanically compensated zoom lenses. J Optics 2006, 35(1), 18-35.

Describes a simple method developed to solve the problem of determining the kinematics of two-component mechanically compensated zoom lenses. It has been shown that a simple paraxial conjugate equation, along with magnification equation can be used successfully to solve the complex problem of component displacement in a two components mechanically compensated zoom lens. This method provides a deep insight into the image formation process by a zoom lens. The method developed is simple to program and provide excellent information about working of two-component mechanically compensated zoom lenses.

5 illus, 14 tables, 15 ref

014725   Singh G S;Bajpai R P (Advanced Optical Processing Division, Central Scientific Instruments Organization, Sector 30, Chandigarh-160 030, Email: gssingh55@yahoo.com) : Desing consideration of three component mechanically compensated zoom lenses. J Optics 2006, 35(1), 1-17.

Presents a simple method to determine the power and air space distribution for three component mechanically compensated zoom lens. Also this paper describes a method developed to solve the complex problem of kinematics determination of three-component mechanically compensated zoom lenses. It has been shown that a simple paraxial conjugate equation, along with magnification equation can be used successfully to solve the problem of component displacement in a three component mechanically compensated zoom lens. This method provides a deep in sight into the image formation process by a zoom lens.

5 illus, 7 tables, 3 ref

014724   Singh A K;Mehrotra N K (Physics Dep, Bareilly College, Bareilly-243 005, Email: ajaykumar301@rediffmail.com) : NMR spin-lattice relaxation time and activation energy in some molecular systems. Indian J pure appl Phys 2006, 45(2), 168-72.

The experimental values of NMR spin-lattice relaxation time (T₁) of N-butylamine, di-isopropylamine, N, N, N-tributylamine, N, N- dimethylformamide, N, N- dimethylacetamide have been reported. The experimental values of T₁, have been correlated with the calculated values of T₁ obtained using various equations of the dielectric relaxation time (τ). It has been concluded that Murty's equation is a better representations of the dielectric relaxation phenomenon. The values of activation energy (ΔE_A) obtained using dielectric relaxation time have been correlated with calculated values obtained using Arrhenius equation of NMR spin-lattice relaxation time (T₁) for these compounds.

2 tables, 17 ref

014723   Shreekanthan K N;Bangera K V;Shivakumar G K; Mahesha M G (Physics Dep, National Institute of Technology, Surathkal, Srinivasnagar-575 025) : Structure and properties of vacuum deposited cadmium telluride thin film. Indian J pure appl Phys 2006, 44(9), 705-8.

Systematic and detailed study of the growth and properties of vacuum deposited cadmium telluride thin films was made. Both p- and n-type films were grown and these films were characterized for their structural, optical, and electrical properties. The crystallographic structure of the deposits was found to be dependent on the rate of deposition. Low deposition rates were observed to result in hexagonal deposits whereas high rates of deposition favoured cubic structure for the film. Electrical and optical properties were also found to be dependent on the deposition parameters.

4 illus, 2 tables, 21 ref

014722   Shivnarayan;Vishvakarma B R (Electronics Engineering Dep, Institute of Technology, Banaras Hindu Univ, Varanasi-221 005, Email: brvish@bhu.ac.in) : Analysis of notch-loaded patch for dual-band operation. Indian J Radio Space Phys 2006, 35(6), 435-42.

Analysis of notch loaded rectangular patch antenna for dual-band operation has been proposed, in which dual frequency behaviour is obtained by notch loading. The theoretical analysis is based on modal expansion cavity model. The resonance frequency changes with the variation in the length and width of the notch. Thus the input impedance, VSWR, return loss and bandwidth are calculated. The obtained resonance frequency ration is variable from 1.17 to 1.77 with the length and width of the notch.

12 illus, 4 tables, 18 ref

014721   Sharma V;Thakur N;Sharma D R;Negi N S;Rangra V S (Physics Dep, H P University, Shimla-171 005, Email: ntb668@yahoo.co.in) : Dielectric relaxation study of binary mixtures of ethyl alcohol and N, N-dimethylformamide in benzene solution from microwave absorption data. Indian J pure appl Phys 2006, 45(2), 163-7.

Dielectric constant (ε') and dielectric loss (ε") of ethanol (C₂H₅OH), and binary mixtures of ethanol and N, N-dimethylformarnide (DMF) in benzene solutions have been measured at microwave frequency 9.883 GHz at different temperatures 25, 30, 35 and 40°C. Standing microwave techniques and Gopala Krishna's [Trans Faraday Soc, 33 (1957)767.] single frequency concentration variation method have been used for above measurements. The measured values of ε' and β" have been used to evaluate dipole moment (μ) and relaxation time (τ). Various thermodynamic parameters (ΔH_ε) ΔF_ε, and ΔS_ε for the dielectric relaxation process of binary mixtures containing 50% mole fraction of OH have been calculated using Eyring's rate equations. Comparison has been made with the corresponding energy parameters for viscous flow process. It is found that the dielectric relaxation process can be treated as the rate process like the viscous flow process. Non-linear variation of relaxation time with molar concentration of ethanol in the whole concentration range of the binary mixture indicates the existence of solute-solute type of molecular association.

5 illus, 2 tables, 18 ref

014720   Sharma P;Koul S K;Chandra S (Center for Applied Research in Electronics, Indian Institute of Technology Delhi, Hauz-Khas, New Delhi-110 016, Email: shiban_koul@hotmail.com) : Studies on RF MEMS shunt switch. Indian J pure appl Phys 2007, 45(4), 387-94.

Radio Frequency Micro-Electro-Mechanical-Systems (RF MEMS) based switches are expected to play a key role in the field of microwave switching. Traits like low-loss performance; zero-power consumption and very low inter-modulation distortion have made these switches well suitable for high-performance microwave and millimeter-wave circuits. The design of RF MEMS switches, however, require sophisticated modeling techniques because of their complicated 3-D geometries with critical aspect ratios and strong in-homogeneities. The effect of various geometric dimensional parameters on the electromagnetic and mechanical behaviour of a shunt capacitive MEMS switch using finite element method based Ansoft High Frequency Structure Simulator (HFSS) software tool has been presented. This exercise will provide a better insight into designing a reliable and high-performance MEMS shunt switch.

11 illus, 4 tables, 5 ref

014719   Sharma D K;Konwar M;Sharma S;Das J;Pal S (Department of Physics, Kohima Science College, Kohima, Nagaland-797 002) : Characteristics of brightness temprature with respect to rain rate over ocean and land and its implication on rain rate retrieval. Indian J Radio Space Phys 2006, 35(4), 259-69.

Studies the characteristics of brightness temperature (BT) with respect to rain rate over ocean and land and its subsequent implication on rainfall retrieval utilizing artificial neural network (ANN). The BTs data are obtained from Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI). Variations of BT with rain rate are compared for all the nine channels over ocean and land, and over ocean 10.67 GHz is found to be most sensitive to rain rate. For 37.0 GHz channels, emission effect is not noticed over land, but it is prominent over ocean for lower value of rain rate. Over land, lower frequency channels (Nos 1-4) are least sensitive to rain rate. From a quantitative comparison of the 85.5 GHz channels over ocean and land, BT difference of <126>10 K is observed. It is also observed that polarization difference between the BTs for this frequency channel is more over ocean. A difference of ~ 10 K and -3 K are noticed over ocean and land, respectively. Neural networks are trained over ocean and land to give rain rate as output. The nine channel BTs from TMI are considered as input for training the networks. The collocated near-surface rainfall rate data from TRMM precipitation radar are considered as target. Correlation values of 0.92 and 0.82 are observed for validation set over ocean and land, respectively, with root mean square error (rmse) values of 2.26 mm/h and 3.54 mm/h. It is observed that rain rate retrieval is better over land after discarding the lower frequency channels. The ANN retrieved rain rate is compared with TMI rain rate and correlations of 0.71 and 0.57 are observed over ocean and land, respectively.

9 illus, 1 table, 22 ref

014718   Sharma A;Verma R C (Department of Physics, Punjabi University, Patiala-147 002, Email: arvind_kks1@rediffmail.com) : Exclusive weak hadronic decays of charmed baryons in flavor SU(3) reanalyzed. Indian J pure appl Phys 2007, 45(3), 189-97.

Two-body exclusive weak hadronic (1/2⁺→1/2⁺ 0') decays of the charmed baryons Λ⁺_c, ⇐⁺_c and ⇐⁰_c are studied employing the SU(3) flavor symmetry. Using the available experimental data on Λ⁺_c→Λ< 112>⁺Σ+π°/< F128><88>°K⁺ decays to fix the reduced amplitudes, predictions are obtained for the branching ratios and asymmetries in the Cabibbo-favored (CF), Cabibbo-suppressed (CS), and Cabibbo-doubly-suppressed (CDS) decay modes. Results obtained are consistent with the available data.

2 tables, 33 ref

014717   Sharma A;Qureshi A;Singh N L;Shrinet V; Avasthi D K;Rakshit A K (Physics Dep, The M S University of Baroda, Vadodara-390 002) : Effect of 50 MeV Li-ion irradiation on thermal and structural characteristics of polymer blends. Indian J pure appl Phys 2006, 45(2), 127-30.

Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA) investigations of pristine and irradiated blended films were carried out. The experimental observations provide a quantitative evaluation of the IR results on the deterioration of chemical bonding with irradiation fluence. It is found that chemical structure is subjected to alteration in intensity with the fluence. It is revealed from TGA thermogram that blended polymer consisting of PVC and EVA in equal composition exhibits better thermal properties. DSC thermograms indicate that T_g has been shifted to lower temperature with broadening of peak, while no change in T_m has been observed up to the fluence of 10¹⁴ ions/cm².

3 illus, 1 table, 6 ref

014716   Sathyanarayana B;Savitha Jyostna T; Satyanarayana N (Chemistry Dep, Kakatiya Univ, Warangal-506 009) : Acoustic studies of binary mixture of N-methylacetamide with some chloroethane and chloroethens at308.15 K. Indian J pure appl Phys 2006, 44(8), 587-91.

The densities and speeds of sound of mixtures of 1,2 dichloroethane, 1,1,2 trichloroethane, 1,1,2,2 tetrachloroethane, trichloroethene and tetrachloroethene with N-methylacetamide, over the entire range of composition, have been measured at a temperature of 308.15 K. The deviations in speed Δu, isentropic compressibility ΔK_S, intermolecular free-length ΔL_F and relative association R_A have been computed using speed and density values. The Δu values are negative whereas ΔK_S and ΔL_F values are positive for all the systems, which indicate the non-specific interactions between unlike molecules. The results are discussed in the light of intermolecular interactions occurring in the solutions. The computed results of ΔKs, have been fitted to a Redlich-Kister type polynomial equation.

1 illus, 3 tables, 125 ref

014715   Saha R K;Roy M K;Karmakar S;Saha S;Sen S K (NO, Saha Institute of Nuclear Physics, 1/AF Bidhanagar, Kolkata-700 064) : Development of an experimental arrangement for precise measurement of angular distribution of ultrasound scattering. Indian J pure appl Phys 2006, 44(9), 661-9.

Describes step-by-step development of a custom-made measurement system and also provides an assessment of the reliability of the set-up. The angular distribution of the scattered field generated by a sufficiently long cylindrical scatterer in water medium has been measured by this system. The measured values have been compared with the theoretical results to validate the instrument. The theoretical curves have been obtained by using the Faran's theory. In this study, an acoustic wave of frequency 2.19 MHz emitted by a medical ultrasound source has been employed to provide energy to the scattering object. Two steel wires of different gauges (0.68mm and 0.91mm in diameter) with size parameters ka ≈ 3.12 and 4.17, respectively, have been taken as prototype scatterers. Here, k is the wave number of the incident wave and a is the radius of the target. Results show that the system is stable, capable of precise scattering measurements and measured values are reproducible. The system has also the flexibility of incorporating scatters of different shapes and also ultrasound probes of different frequencies.

5 illus, 1 table, 18 ref

014714   Rudra Pratap;Arunkumar A (Department of Mechanical Engineering, CranesSci MEMS Lab, Indian Institute of Science, Bangalore-560 012) : Material selection for MEMS devices. Indian J pure appl Phys 2007, 45(4), 358-67.

As MEMS design matures and migrates from process centric design to performance based design, MEMS designers would need a rational method for selecting an appropriate material that is not based on ease of processing alone. While there is a growing number of thin film materials that can be used in inicromachining for MEMS devices, the selection of a particular material is rarely based on quantifiable criterion that relates directly to the optimum performance of the device. In this study, we present a methodology for creating material related device performance indices that can be used for selecting best possible material for a device. This study is inspired by the Ashby approach and its extension to the microworld in recent studies, where materials are graded on material performance indices and the most appropriate material is selected from the Ashby charts so created. We extend this concept further in this paper and create device performance indices that can be used to grade MEMS materials in performance parameter space. We first create and discuss a material index for thermoelastic damping, an important index for vacuum packed dynamic MEMS devices that has been missing from the list of performance indices previously considered. Presents two case studies of material selection, for a MEMS gyroscope and a MEMS ultrasound transducer, to illustrate the methodology and show two different approaches for creating optimality criterion in the presence of several competing performance indices.

5 illus, 4 tables, 20 ref

014713   Rout S K;Panigrahi S P (Physics Dep, National Institute of Technology, Rourkela-769 008) : Mechanism of phase formation of BaTiO₃-SrTiO₃ solid solution through solid oxide reaction. Indian J pure appl Phys 2006, 44(8), 606-11.

The formation of solid solution composition Ba_0.5Sr_0.5TiO₃, from BaCO₃, SrCO₃ and TiO₂ powders has been studied through solid oxide reactions using TGA/DSC and XRD. The compound BaCO₃ decomposes at much lower temperature in the mixture due to the presence of acidic TiO₂. BaTiO₃ (BT) and SrTiO₃ (ST) which start forming from the temperatures 700 and 800°C, respectively without formation of BaO/SrO or any titanate phases. Rietveld refinement shows the rate of formation of BT is relatively higher than that of ST. The solid solution Ba_0.5Sr_0.5TiO₃ (BST (ss)) starts forming from 1000°C. The rate of formation of BaTiO₃ is higher than that of SrTiO₃. Activation energy for formation of BaTiO₃ (40.41 kcal/mol) is higher than that of SrTiO₃ (58.867 kcal/mol) in the system. Lattice parameter of initial solid solution phase is higher indicating that the BST forms with the interface of BT. The final BST (ss) formation requires more activation energy (76.999 kcal/mol) than initial BT and ST.

5 illus, 1 table, 128 ref

014712   Roshan Lal;Suman;Sharma N D;Taneja S P;Reddy V R (Department of Physics, Kurukshetra University, Kurukshetra-136 119) : Structural and magnetic properties of zinc ferrite aluminates. Indian J pure appl Phys 2007, 45(3), 231-7.

Zinc ferrite aluminates ZnAl_xFe_2-xO₄ with composition (0≤x ≤1) were synthesized at 1150°C using the usual ceramic method and studied by X-ray diffraction, magnetization and Mossbauer measurements. It is observed that lattice parameter decreases, with increasing Al concentration (x). Mossbauer absorption spectra of all the samples recorded at room temperature showed three hyperfine magnetic sextets and a single quadrupole doublet. The outer sextet is assigned to α- Fe₂O₃ crystalline phase, whereas inner two sextets refer to Fe³⁺ ions at octahedral (B) site and tetrahedral (A) site showing the formation of zinc ferrite aluminates phase. The hyperfine magnetic field was found to decrease with increasing Al concentration and has been explained on the basis of super transferred hyperfine field. The central doublet is partially dissociated forming ZnFeO₂ (delafossite) phase overlapping the main Mossbauer spectra measured at room temperature. The observed variations in saturation magnetization in all the samples have been explained on the basis of site distribution and the strength of the exchange interactions between the magnetic ions. On the basis of these observations, it is concluded that the present ferrite system exhibits a non-collinear magnetic structure with a very weak ferromagnetic character, which starts dominating further when zinc ferrite is diluted with non-magnetic Al³⁺ ions.

5 illus, 2 tables, 21 ref

014711   Rastogi V K;Palafox M A;Lang K;Singhal S K; Soni R K;Sharma R (Physics Dep, CCS Univ, Meerut-250 004) : Vibrational spectra and thermodynamics of biomolecule: 5-chlorocytosine. Indian J pure appl Phys 2006, 44(9), 653-60.

The laser Raman and IR spectra of biomolecule 5-chlorocytosine have been recorded in solid phase. The vibrational spectra have been analysed assuming planar geometry and C_s point group symmetry for the molecule and observed fundamentals have been assigned to different normal modes of vibrations. The studies indicate that the features that are characteristic of the vibrational spectra of cytosine and its derivatives are retained by the spectrum of 5-chlorocytosine and it exists in amino-oxo form in solid phase. The validity of empirical relation vs = 345.5 + 0.876 v_asym suggests the equivalence of the two NH bonds of the NH₂ group. The observed fundamental frequencies are used to calculate the thermodynamic functions, namely, the enthalpy, entropy, heat capacity and the free energy were also computed in the temperature range 200-1000K using the rigid-rotor harmonic oscillator approximation. For this purpose, the fundamental wavenumbers obtained in the present study were taken, while the structural parameters were taken from literature.

7 illus, 2 tables, 49 ref

014710   Ranjan R R;Ganguly N D;Joshi H P;Iyer K N (Department of Physics, Saurashtra University, Rajkot-360 005) : Aerosol optical depth and precipitable water vapour content at Rajkot, a tropical semi-arid station. Indian J Radio Space Phys 2007, 36(1), 27-32.

Aerosol optical depth (AOD) at 1020 nm for the period July 2004 - July 2005 and at six different wavelengths ranging from 380 nm to 1020 nm for March-June 2005 is studied. The measurements are being made at the tropical semi-arid location Rajkot (22°18' N, 70°44' E, 142 m above sea level) using a hand-held microprocessor-based sun photometer, MICROTOPS-II under the aegis of ISRO's Geosphere Biosphere Programme (IGBP). Prectpitable water vapour is estimated from the measurements of solar intensity at 936 nm and 1020 nm. The AOD shows seasonal variation with high values (0.41) in summer and low values (0.11) in winter. Angstrom wavelength exponent a has been found to be high (0.59) during March, indicating relative dominance of accumulation-mode particles. During summer season, low value (0.25) of Angstrom wavelength exponent a indicates relative dominance of coarse-mode particles. The changes in the column water vapour have been found to be correlated with the changes in AOD. This is supported by the observed increase of AOD with relative humidity at high humidity values.

7 illus, 22 ref

014709   Ramanamurthy P V M;Ahrens R;Karmalkar S (Department of Electrical Engineering, Indian Institute of Technology, Madras-600 036, Email: karmal@ee.iitm.ac.in) : Piezoelectric microvalve. Indian J pure appl Phys 2007, 45(4), 278-81.

A normally closed microvalve is a very important component of a microfluidic system. The fabrication of an active, normally-closed piezoelectric microvalve useful for automated drug delivery or control of fluids in microreactor systems has been studied. The microvalve has dimensions of 19 mm x 19 mm x 7 mm, an inlet diameter of 200 μm, a dead volume of 0.33 μl and has a steady-state flow-rate of about 240 seem.

5 illus, 6 ref

014708   Rama Rao G V;Sandhya Sri P B;Viswanatha Sarma A;Rambabu C (Physics Dep, Dharma Appa Rao College, Nuzvid-521 201) : Comparative study of theoretical ultrasonic velocities of binary mixtures of methanol and pyridine at different temperatures. Indian J pure appl Phys 2006, 45(2), 135-42.

Theoretical velocities of binary liquid mixtures of methanol with piperidine and morpholine and pyridine with piperidine and morpholine at 303.15, 308.15, 313.15 and 318.15K have been evaluated by using theoretical models of liquid mixtures such as Nomoto, Van Dael-Vangeal, impedance dependence, Rao's specific velocity method and Junjie's relations. Ultrasonic velocity and density of these mixtures have also been measured as a function of concentration and temperature and the experimental values are compared with theoretical values. A good agreement has been found between experimental and Nomoto's ultrasonic velocities. U²_exp/U²_imx has also been evaluated for non-ideality in the mixtures. The relative applicability of these theories to the present systems have been investigated. The results are explained in terms of intermolecular interactions occurring in these binary liquid mixtures.

4 illus, 18 tables, 32 ref

014707   Rajput S;Chaudhary S;Kashyap S C;Srivastava P (Physics Dep, Indian Institute of Technology, New Delhi-110 016, Email: sujeetc@physics.iitd.ernet.in) : On the study of phase formation and critical current density in superconducting MgB₂. Bull Mater Sci 2006, 29(3), 207-11.

Superconducting bulk MgB₂ samples have been synthesized by employing sintering technique without using any additional process steps, generally undertaken in view of the substantial loss of magnesium, during heat treatment. Starting with Mg rich powders having different atomic ratios of Mg: B, as against the nominally required Mg :B = 1:2 ratio, authors have obtained superconducting MgB₂ samples of different characteristics. The effect of excess Mg in the starling mixture and processing temperature on the phase-formation, transition temperature (T_c) and critical current density (J_c) have been investigated by electrical transport and a.c. susceptibility measurements. The X-ray diffraction and X-ray photoelectron spectroscopic analyses of MgB₂ bulk samples have been carried out to understand the role of excess Mg and the effect of processing temperature. It is established that MgB₂ samples with high critical current density can be synthesized from a Mg rich powder having Mg: B in 2:2 ratio, at temperatures around 790°C. Critical current density has been found to vary systematically with processing temperature.

4 illus, 1 table, 29 ref

014706   Rajnikant;Dinesh;Deshmukh M B;Kamni (Condensed Matter Physics Group, Postgraduate Dep of Physics, Jammu Univ, Jammu Tawi-180 006) : Synthesis, crystal structure and study of X-H...A interactions in N,N'-bis-(4-methoxy-benzylidine)-hydrazine. Indian J pure appl Phys 2006, 44(8), 602-5.

Synthesis and crystal structure of N,N'-bis-(4-methoxy-benzylidine)-hydrazine have been reported. The title compound crystallizes in the monoclinic space group C2/c with unit cell parameters a = 17.416(3), b = 10.711(3) and c =8.428(3)Angstrom, β =113.64(2)°, V = 1440.2(8)Angstrum³3 and Z = 4. The structure has been refined to a R-value of 0.038 for 937 observed reflections. The molecules adopt columnar packing in the unit cell and the crystal structure is stabilized by two intra- and five intermolecular hydrogen bonded interactions.

3 illus, 17 ref

014705   Rajesh Kumar;Rajendra Prasad, (Applied Physics Dep, Z H College of Engineering & Technology, Aligarh Muslim University, Aligarh-202 002, Email: drrajesh04@rediffmail.com) : Measurement of radon and its progeny levels in dwellings of Srivaikuntam, Tamilnadu. Indian J pure appl Phys 2006, 45(2), 116-18.

Measurements of indoor radon concentrations were performed in the dwellings in one hundred twenty rooms in the dwellings of Srivaikuntam town of Tamilnadu in Southern India by using Solid State Nuclear Track Detectors (SSNTD's). The SSNTDs were hung in different type of rooms such as office rooms, living rooms, bedrooms, kitchens and laboratories for 120 days exposure time. The indoor radon levels have been measured which are found to be in the range 30-287 Bqm^-3. The mean annual radon effective dose equivalent in living rooms was estimated to be mSv. The average life time risk of lung cancer from the chronic radon progeny exposure is estimated to be 6.8 x 10^-3 (0.68%).

4 tables, 14 ref

014704   Rajesh Kumar;Prasad R (Applied Physics Dep, Z H College of Engineering & Technology, Aligarh Muslim Univ, Aligarh-202 002, Email: drrajesh04@rediffmail.com) : Study of <. Indian J pure appl Phys 2006, 44(9), 649-52.

Polymer films are finding many applications like in ion track registration, microfilters for gas separation, water purification etc. Positron Annihilation Lifetime Spectroscopy (PALS) provides non-destructive and non-interfering probe, having high detection efficiency for free volume hole properties. Makrofol - KL polycarbonate films (22 μm) were irradiated by ^l36Xe (11.56 MeV/n) with the fluences of 10⁵ ions/cm². Ion beam modifications were studied by PALS technique. From the o-Ps lifetime, mean free volume, hole radius and microvoid volume have been obtained which are found to increase with irradiation.

1 illus, 2 tables, 18 ref

014703   Qiang X;Zhaoying Z;Junhua Z;Yanying F;Dong L; Guibin D (State Key Laboratory of Precision Measurement Technology and Instrumen, Tsinghua University, Beijing, China 100 084, Email: serzha@gmail.com) : Piezoelectrically actuated array microjet for biochemical purpose. Indian J pure appl Phys 2007, 45(4), 273-7.

Presents a micromachining-based piezoeleotrically actuated array microjet for biomedical purposes such as inhalation drug therapy (IDT) and drug microencapsulation. The microjet consists of a reservoir and a fluid chamber, which is formed by a piezoelectric transducer bonded to a silicon chip with numerous micro nozzles. Inside the fluid chamber, a continuous pressure wave generated by the piezoelectric transducer propagates towards the silicon chip and squeezes the liquid out through the nozzles. The pressure wave in fluid chamber is numerically simulated using finite elements method to give a reference for nozzles arrangement. Diameter and velocity measurements of droplets, temperature estimations on working device and a preliminary animal experiment of IDT are done to characterize the microjet. As a result, the microjet could be a promising tool in biomedicine field.

8 illus, 8 ref

014702   Pushpanjali G M;Konda R B;Mulgi S N;Satnoor S K;Hadalgi P M;Hunagund P V (Applied Electronics Dep, Gulbarga Univ, Gulbarga-585 106) : Design of wideband equilaterial triangular microstrip antennas. Indian J Radio Space Phys 2006, 35(6), 443-7.

A novel design of corporate fed two-element slotted equilateral triangular microstrip array antenna (SETMSA) for enhancing the impedance bandwidth and gain is presented. The experimental results show improvement in both impedance bandwidth and gain compared to the conventional two-element equilateral triangular microstrip array antenna (ETMSA) without changing much the radiation characteristics. A study is also made by using a common rectangular parasitic element in the form of gap coupled between the two slotted equilateral triangular microstrip elements, and the antenna is fed by aperture-coupled feeding technique. This modified antenna further enhances the impedance bandwidth and it operates for three bands of frequencies. If a slot is inserted in the parasitic element, the antenna operates at two nearly equal widebands of frequencies. This type of wideband and multiband operation of antenna may find application in wireless communication.

9 illus, 1 table, 13 ref

014701   Prasad P B V;Sashikant P B;Neelima P (SR Research Laboratory for studies in Crystillization Phenomena, 10-1-, , Mamillaguda, Khammam-507 001, Email: drpbvprasad@rediffmail.com.) : Power XRD studies on n-C₂₈H₅₈:n-C_xH_2x+2(x = 10, 12, 14, 16, 18) hydrocarbon mixture: phase strength analysis. Bull Mater Sci 2006, 29(3), 213-9.

Powder XRD investigations were made on mixtures of title compounds and strength of monoclinic, orthorhombic and super-lattice phases were evaluated. Interpretations were made in terms of the influence of tunnel-like defects (TLIDs) and a linear relationship was noticed between the strength of orthorhombic phase and <193>l_TLID<62>.

6 illus, 3 tables, 22 ref

014700   Prajapati A N;Rana V A;Vyas A D (Physics Dep, School of Science, Gujrat Univ, Ahmedabad) : Microwave absorption and relaxation studies of binary mixtures of fluoro substituted anilines with some primary alcohols in benzene solutions. Indian J pure appl Phys 2006, 44(8), 620-4.

Complex permittivity at 9.1 GHz, static permittivity at 455 kHz and refractive index at optical frequency of methanol, ethanol, 1-propanol, 2-fluoroaniline, 4-fluoroaniline and their binary mixtures have been measured at a single temperature (30°C) in dilute solution of non-polar solvent benzene. The measured values of permittivity and dielectric loss have been used to evaluate distribution parameter (α) and relaxation times τ₀, τ₁, τ₂ and dipole moment (μ). The variation of relaxation time versus concentration suggests solute-solute/solute-solvent type of association through hydrogen bonding.

3 tables, 23 ref