Thermodynamic Properties of the Internal Rotation in Methyl Alcohol Vapor from 200 to 500°K

At ordinary and lower temperatures the thermodynamic properties of the methyl alcohol internal rotation are beyond the limits of available tabulations. For any internal rotator, of a given symmetry, with a fixed moment of inertia and potential barrier, two limiting values of each property can be calculated for any chosen temperature. Available tables are restricted to those cases for which the differences between the limiting values can be neglected. When, as with methyl alcohol, the differences are large, the representative values can be found by taking proper account of the symmetry and the dependence of the internal rotator energy levels upon the external rotations.For methyl alcohol, the correct intermediate thermodynamic properties are obtained by using for the partition function and its derivatives the numerical mean of the limiting values of these sums obtained for the general rotator. This simple rule, however, is not necessarily applicable to other compounds.Heat capacities and entropies, calculated from the spectroscopic potential barrier of 932 cal./mole and other molecular constants, are considered in relation to experimental data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69898/2/JCPSA6-18-8-1051-1.pd

Hindered Rotation in Methyl Alcohol with Note on Ethyl Alcohol

The potential barrier to the internal rotation in methyl alcohol is recalculated from the entropy with the aid of new molecular dimensions generously provided by Burkhard and Dennison. The barrier calculation is examined for temperature dependence and checked for reliability by recalculation with the Clapeyron equation substituted for parts of the data. The result is 1600±700 cal./mole, which includes the new spectroscopic barrier of Burkhard and Dennison at 326 cm−1. Within the range covered by the result, a residual entropy up to 0.50 cal./mole deg. is possible, and the retention of 0.46 e.u. by the crystal is consistent with a reasonable simple assumption about the distribution of hydrogen bonds.It is suggested, by analogy, that the barrier to the hydroxyl group rotation in ethyl alcohol should be about 1000 cal./mole.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71293/2/JCPSA6-18-3-361-1.pd

Transport coefficients and nonextensive statistics

We discuss the basic transport phenomena in gases and plasmas obeying the $q$-nonextensive velocity distribution (power-law). Analytical expressions for the thermal conductivity ($K_q$) and viscosity ($\eta_q$) are derived by solving the Boltzmann equation in the relaxation-time approximation. The available experimental results to the ratio {$K_q$}/$\eta_q$ constrains the $q$-parameter on the interval $0.74 \leq q \leq 1$. In the extensive limiting case, the standard transport coefficients based on the local Gaussian distribution are recovered, and due to a surprising cancellation, the electric conductivity of a neutral plasma is not modified.Comment: 14 pages, 3 figures, REVTEX, submitted to PR

Bostonia. Volume 13

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

The Distribution and Reproductive Success of the Western Snowy Plover along the Oregon Coast - 2006

Part of the Oregon Bidiversity Information Center Repor

Decoupling electrocaloric effect from Joule heating in a solid state cooling device

We report a heat dynamics analysis of the electrocaloric effect (ECE) in commercial multilayer capacitors based on BaTiO3 dielectric, a promising candidate for applications as a solid state cooling device. Direct measurements of the time evolution of the sample's temperature changes under different applied voltages allow us to decouple the contributions from Joule heating and from the ECE. Heat balance equations were used to model the thermal coupling between different parts of the system. Fingerprints of Joule heating and the ECE could be resolved at different time scales. We argue that Joule heating and the thermal coupling of the device to the environment must be carefully taken in to account in future developments of refrigeration technologies employing the ECE.Comment: Acepted to be published in Applied Phys. Letters (2011

The Infra‐Red Absorption Spectra of Ethylene and Tetra‐Deutero‐Ethylene under High Resolution

The fine structure of several infra‐red absorption bands of C2H4 and C2D4 have been resolved. From the rotational constants so found, the C☒C and C☒H distances in this molecule were calculated to be 1.353 and 1.071A, and the H☒C☒H angle to be 119°55′. An assignment of fundamental frequencies has been made which is consistent with the observed data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69770/2/JCPSA6-10-2-88-1.pd