Thermal Stresses in an Accreting Medium with Heat Generation

In this paper, the problem of a semi-infinite accreting medium moving with a constant velocity is studied. The heat generation in the medium begins at a constant rate and continues indefinitely. Using the modified heat conduction theory, temperature distribution was determined and the associated thermoelastic problem was solved with Laplace transform technique. The results are evaluated numerically and presented graphically

Free Volumes of Aqueous Nonelectrolytes

510-51

Excess Thermodynamic Functions of Water + Pyridine System

724-72

Temperature dependence of lattice energy of fluorite type AB₂ crystals, alkaline earth oxides and heavy metal halides – Evaluation from sound velocity data

660-663Lattice energies of CaF2, SrF2, BaF2, CdF2, EuF2, MgO, SrCl, AgCl and TlBr at different temperatures have been evaluated making use of single crystal elastic constant data and employing Kudriavtsev’s theory which relates the lattice energy of the crystal, U, with mean sound velocity, um, in the crystal. The lattice energies of both MgO and SrO decrease with increase in temperature and the variations are parabolic and similar. The lattice energies of AgCl and TlBr vary with temperature parabolically up to 80 K and thereafter linearly up to 300 K. The results are explained in terms of the structure of the crystals, mutual interaction of the ions and anharmonic effects associated with as a function of temperature

Lattice energy of mixed alkali halide crystals:Evaluation from sound velocity studies

495-498Based on single-crystal elastic constant data and employing Kudriavtsev's theory, which relates the lattice energy of the crystal U to the mean sound velocity μm in the crystal, the lattice energies or NaCl-KCl, NaBr-KBr, Kl -KBr and KCl-RbCl mixed crystals have been evaluated. In general, the lattice energies of these mixed crystal have been found to decrease with increase in the concentration of the second component. The present study highlights the application of Kudriavtsev's theory in predicting the lattice energies of mixed ionic crystals making use of sound velocity measurements

Ultrasonic studies on dilute solutions of water in <i>n</i>-alcohols and 2-alkoxyethanols

259-264Ultrasonic velocities in dilute solutions of water in n-alcohols (methanol, ethanol, n-propanol and n-butanol), and 2-alkoxyethanols (2-methoxyethanol, 2-ethoxyethanol and 2-butoxyethanol) have been determined at 298.15 K using single crystal variable path interferometer working at 3 MHz. The excess ultrasonic velocities have been evaluated using the formula, which is thermodynamically valid. A distinctive non-linear variation of ultrasonic velocity with concentration of water in both n-alcohols and 2-alkoxyethanols has been observed over a small range of concentration. A similar behaviour is also observed in the concentration dependence of excess ultrasonic velocity in these solutions. This behaviour has been explained by considering the existence of water molecules as monomers up to certain optimum concentration, (X2)opt, of water and the non-linear behaviour observed beyond (X2)opt has been explained in the light of water-water and water-alcohol interactions leading to the formation of islands of water-alcohol extended structures

Effect of ammonium halides on the temperature of sound velocity maximum of water

683-689<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Effect of ammonium halides on the temperature of sound velocity maximum (TSVM) of water has been studied by determining the ultrasonic velocity with an accuracy of ± 0.003 % using <span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">single- crystal <span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">variable-path interferometer working at 3 MHz. The velocity measurements were carried out at = 2°C intervals over a range of 5 °C to either side of the TSVM of the solutions. The accuracy in fixing the TSVM is ± 0.2 °C. The shift in TSVM of water due to the addition of the NH4Cl, Δ Tobs is found to be positive up to w = 3.4×10-2 and negative thereafter, where w represents weight fraction of the solute. The shifts in TSVM of water due to the addition of the NH4Br and NH4I are found to be negative throughout the concentration range. The structural contribution to the shift in TSVM of water, ΔTstr , is found to be positive for NH4Cl and increases with increase in the concentration nonlinearly. ΔTstr for NH4Br is almost zero up to w = 3×10-2 and thereafter becomes negative. ΔTstr for NH4I is found to be negative throughout the concentration range. The results are explained in terms of the structure, making and breaking nature of anions and cations present in the solutions.</span

Ultrasonic studies in dilute solutions of water and nonelectrolytes

10-14<span style="font-size:16.0pt;mso-bidi-font-size: 11.0pt;line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";color:black;mso-ansi-language:en-in;mso-fareast-language:="" en-us;mso-bidi-language:hi"="" lang="EN-IN">Ultrasonic velocities in dilute solutions of water in n-propanol, isopropanol<span style="font-size:16.0pt; mso-bidi-font-size:11.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";mso-ansi-language:en-in;mso-fareast-language:="" en-us;mso-bidi-language:hi"="" lang="EN-IN">, glycerol, formamide. N-methyl formamide, dimethyl formamide tetrahydrofuran and propylene glycol have been determined 298.15 K using single crystal variable path interferometer working at 3 Mhz. Excess sound velocities, have been evaluated using the formula which is thermodynamically valid. Both the ultrasonic velocity and excess ultralsonic velocity have been found to vary nonlinearly with concentration in the high dilution range of water in non electrolytes studied. The results are explained by considering the existence of water molecules <span style="font-size:15.5pt;mso-bidi-font-size:10.5pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";color:black;="" mso-ansi-language:en-in;mso-fareast-language:en-us;mso-bidi-language:hi"="" lang="EN-IN">as monomer up to certain optimum concentration (X2)opt of water and the nonlinear behaviour observed beyond<span style="font-size:12.5pt;mso-bidi-font-size:7.5pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";color:black;="" mso-ansi-language:en-in;mso-fareast-language:en-us;mso-bidi-language:hi"="" lang="EN-IN"> <span style="font-size:15.5pt;mso-bidi-font-size:10.5pt;line-height:115%; font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-us;mso-bidi-language:="" hi"="" lang="EN-IN">(X2)opt <span style="font-size: 16.0pt;mso-bidi-font-size:11.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";color:black;mso-ansi-language:en-in;="" mso-fareast-language:en-us;mso-bidi-language:hi"="" lang="EN-IN">has been explained in the light water-water and water- nonelectrolyte interactions leading to the formation of island of water-nonelectrolyte complexes.</span