Articles written in Pramana – Journal of Physics

    • Converging shock waves in metals

      H S Yadav V P Singh

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      Study of propagation of a spherically converging shock wave has been carried out by Whitham’s method. The variation of shock velocity and pressure along the radius of curvature has been calculated numerically for a number of metals. Attempt has also been made to compare the experimental results of velocity of detonation wave with those reported elsewhere by the application of Whitham’s method. A good agreement between experimental and theoretical results has been obtained in this study.

    • Effect of thermal pressure in converging detonation waves

      V P Singh

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      Propagation of converging detonation waves in various explosives is studied using the equation of state, which considers both the thermal and elastic pressures. It is seen that the rate of increase of thermal pressure is higher than that of the elastic pressure during convergence. The present equation of state is better since it also gives the variation of temperature, whereas the polytropic form of the equation of state is independent of temperature. It is seen that the total detonation pressure is slightly greater than the elastic pressure. Results are compared with those reported elsewhere.

    • Simulation of pressure-space-time history in underwater explosions

      V P Singh A M N Yogi

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      Pressure-space-time history of shock waves due to the detonation of explosive charge in water is obtained by simulating the numerical integration of shock trajectory with the variation of fluid parameters behind the shock front. Results are compared with those obtained experimentally elsewhere.

    • Electro-optical characterization and analysis of CuPc-based solar cells with high photovoltage

      V P Singh R S Singh A M Hermann

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      Organic solar cells using the CuPc and PTCBI semiconductor layers were studied. A high open circuit voltage of 1.15 V was obtained in a device with ITO/PEDOT:PSS/CuPc (15 nm)/PTCBI (7 nm)/Al structure. Results were interpreted in terms of a modified CuPc-Al Schottky diode for the thin PTCBI case and a CuPc-PTCBI heterojunction for the thick PTCBI case. Also, the formation of a thin aluminum oxide layer under the aluminum electrode was postulated. This layer has a beneficial aspect wherein shunting losses are reduced and a high photovoltage is enabled. However, it adds greatly to the series resistance to a point where the short circuit current density is reduced. CuPc Schottky diodes with an ITO/PEDOT:PSS/CuPc/Al structure yielded a high Voc of 900 mV for a CuPc layer of thickness 140 nm. The Voc increased with increase in CuPc layer thickness.

    • Current nanoscience and nanoengineering at the Center for Nanoscale Science and Engineering

      A M Hermann R S Singh V P Singh

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      The Center for Nanoscale Science and Engineering (CeNSE) at the University of Kentucky is a multidisciplinary group of faculty, students, and staff, with a shared vision and cutting-edge research facilities to study and develop materials and devices at the nanoscale.

      Current research projects at CeNSE span a number of diverse nanoscience thrusts in bio-engineering and medicine (nanosensors and nanoelectrodes, nanoparticle-based drug delivery), electronics (nanolithography, molecular electronics, nanotube FETs), nanotemplates for electronics and gas sensors (functionalization of carbon nanotubes, aligned carbon nanotube structures for gate-keeping, e-beam lithography with nanoscale precision), and nano-optoelectronics (nanoscale photonics for laser communications, quantum confinement in photovoltaic devices, and nanostructured displays).

      This paper provides glimpses of this research and future directions.

    • Monte Carlo simulation for the estimation of iron in human whole blood and comparison with experimental data


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      Monte Carlo N-particle (MCNP) code has been used to simulate the transport of gamma photon rays of different energies (22, 31, 59.5 and 81 keV) to estimate the iron content in solutions. In this study, MCNP simulation results are compared with experiment and XCOM theoretical data. The simulation shows that theobtained results are in good agreement with experimental data, and better than the theoretical XCOM values. The study indicates that MCNP simulation is an excellent tool to estimate the iron concentration in the blood samples. The MCNP code can also be utilized to estimate other trace elements in the blood samples.

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