Open Access Short Research Article

Maxwell Relations for Substances with Negative Thermal Expansion and Negative Compressibility

Igor A. Stepanov

Physical Science International Journal, Page 1-6
DOI: 10.9734/PSIJ/2017/33660

It is shown that taking into account the negative compressibility of substances changes Maxwell relations. The earlier results of the author indicating that these relations differ for substances with negative thermal expansion have received additional confirmation. Universal Maxwell relations have been derived. The results obtained have been confirmed experimentally by a number of authors.

 

Open Access Original Research Article

Health Detriment Associated with Exposure to Natural Radioactivity from the Soil of Ondo and Ekiti States South Western, Nigeria

A. E. Ayodele, A. M. Arogunjo, J. I. Ajisafe, O. T. Arije

Physical Science International Journal, Page 1-11
DOI: 10.9734/PSIJ/2017/32273

The health detriment associated with human exposure to primordial radionuclides from the earth crust has been a major source of concern to public health observers across the globe. The level of such detriment can be mitigated by continuous monitoring in order to ascertain that the safe threshold is maintained from time to time. In the light of the above, the activity concentrations of naturally occurring radioactivity (i.e 232Th, 226Ra and 40K) were determined in seventeen soil samples collected from selected cities across Ondo and Ekiti States using gamma ray spectrometry. The measured activity concentrations ranged from 31.93±1.77 to 227.50±4.43 Bq Kg-1 for 232Th, 45.60±2.99 to 210.36±8.76 Bq Kg-1 for 226Ra, 364.89±6.40 to 1274.57±12.48 Bq Kg-1 for 40K, and 48.64±2.04 to 207.22±5.50 Bq Kg-1 for 232Th, 73.52±3.81 to 209.15±7.45 Bq Kg-1 for 226Ra, 542.26±10.41 to 2348.86±21.83 Bq Kg-1 for 40K for Ondo and Ekiti States, respectively. Absorbed dose was calculated using the measured activity concentrations. The mean absorbed dose rate and standard deviation in nGy h-1 were 140.89±65.27 and 173.27±85.40 for Ondo and Ekiti States, respectively. These results are beyond the limits (30 nGy h-1-70 nGy h-1) recommended by UNSCEAR, 1988 for area of normal background radiation. Health detriment to various organs of the body resulting from the exposure scenario was evaluated.

 

Open Access Original Research Article

Far-infrared Spectra of the Alloy of Germanium-Antimony-tellurium in the Glassy and Crystalline State

V. A. Ryzhov, D. Arsova

Physical Science International Journal, Page 1-8
DOI: 10.9734/PSIJ/2017/33572

Far-infrared spectra of a germanium-antimony-tellurium alloy in the glassy and crystalline states have been measured and analyzed in the frequency range 20–400 cm-1 at room temperature. The absorption in this range is due to the phonon modes of the structural units of crystalline and correlated librational vibrations (boson peak) of glassy alloy, which precede the appearance of relaxation dynamics. The vibrational assignments of various absorption bands and the differences revealed in the spectra will make it possible to more confidently elucidate the possible molecular mechanism of the crystal-to-amorphous transition in other chalcogenide alloys. New details of the crystal-to-amorphous transition scenario are suggested.

 

Open Access Original Research Article

Deposition of Silicon Films from Liquid Cyclopentasilane Precursors Using High Pressure Spray System

H. Frey, R. Lauth, H. R. Khan, N. Eisenreich, A. Koleczko

Physical Science International Journal, Page 1-12
DOI: 10.9734/PSIJ/2017/33788

Si- films were deposited from liquid precursors, especially cyclopentasilane using a high pressure spray deposition system based on an electronically controlled piezo-injector in a inert gas atmosphere. This equipment might be applicable to other liquid precursors and targeted thin Si-films of importance. The thermal properties and reactivity with oxygen of pure liquid cyclopentasilane and its solutions in toluene are investigated by temperature dependent FTIR-Spectroscopy and Differential Scanning Calorimetry. The homogenous films of silicon in µm range thickness are deposited from pure liquid cyclopentasilane and its solutions in toluene on rigid carbon glass plates and on flexible carbon glass fiber substrates using a high pressure spray deposition system. The morphological and structural properties of the silicon films were investigated. These results and the chemical analysis of the films show that the annealed films are homogenous, adhesive and consist of pure polycrystalline silicon. The silicon films deposited from liquid cyclopentasilane in toluene solutions show cracks, whereas silicon films deposited from pure cyclopentasilane are cracks free over at least 400 cm2 and might enable to develop large area solar cells.

 

Open Access Original Research Article

Effect of Prandtl Number and Inclination Angle on MHD Natural Convection in Inclined Open Square Cavity

Sheikh Anwar Hossain, M. A. Alim, Satrajit Kumar Saha

Physical Science International Journal, Page 1-13
DOI: 10.9734/PSIJ/2017/33067

MHD natural convection and fluid flow in a two-dimensional open and inclined square cavity with a heated circular cylinder was considered in this work. The opposite wall to the opening side of the cavity was first kept to constant heat flux q, at the same time the surrounding fluid interacting with the aperture was maintained to an ambient temperature T¥. The top and bottom wall was kept to low and high temperature respectively. As a result a natural convection is formed in the cavity due to buoyancy force and temperature difference in the cavity. The governing equations for mass, momentum and energy conservation are expressed in a normalized primitive variables formulation. The streamlines and isotherms are produced, heat transfer parameter Nu are obtained for Prandtl number Pr = 0.72, 2, 5, 7 and inclination angles from 0°, 5°, 20°, 35°, 50° for fixed Hartmann number 60. The results are presented in graphical as well as tabular form. In the result it is found that heat flux is increasing function of Prandtl number Pr, while Rayleigh number is 10000 and heat flux is maximum when inclination angle is 5°. It is observed that fluid moves counterclockwise around the cylinder. Various recirculations are formed around the cylinder and one small vortex is formed into the flow field for 50° inclination and Pr = 0.72 near the cylinder. The almost all isotherm lines are concentrated at the right lower corner of the cavity. The present result agree with the existent heat transfer and boundary layer theory.