Molecular derivation of the hydrodynamic equations for a binary fluid

In this paper, the hydrodynamic equations and the associated transport coefficients are derived for a simple binary fluid from molecular considerations. This is a generalization of the methods of Felderhof and Oppenheim and of Selwyn to multicomponent systems. A linear response formalism is used to describe the relaxation of the binary system from an initial nonequilibrium state. Explicit molecular expressions are given for the transport coefficients in terms of time correlation functions of generalized current densities. These densities have the useful property of not containing a conserved part. The correlation functions are then related to a set of phenomenological coefficients in the theory of nonequilibrium thermodynamics. This explicit identification enables one to relate the correlation functions to experimentally measured transport coefficients.Supported by the National Science Foundation.     

Electrocapillarity behavior of Au111 in SO4(2-) and F-

We present the first set of results measuring the change in interfacial free energy and surface stress for Au(111) electrodes in an electrolyte containing a nonspecifically adsorbing anion and compare this behavior to that in an electrolyte containing an anion known to undergo specific adsorption. Generally, we find that the surface stress is more sensitive to changes in electrode potential and adsorption then the interfacial free energy. The results obtained in fluoride electrolytes are compared to the predictions of a thermodynamic analysis.     

Perovskite-like La1−xKxMnO3 and related compounds: Solid state chemistry and the catalysis of the reduction of NO by CO and H2

The new compounds La_1?xM_xMnO₃ (0.05 ? x ? 0.4 for M = K; x = 0.2 for M = Na, Rb) have been prepared. La_1?xK_xMnO₃ (0.05 ? x ? 0.4), LaMnO_3.01, LaMnO_3.15, La_0.8Na_0.2MnO₃, and La_0.8Rb_0.2MnO₃ have been used as catalysts in the reduction of NO. La_0.8K_0.2MnO₃ has also been used in the catalytic decomposition of NO. The activity of these catalysts is related to the presence of a Mn³⁺/Mn⁴⁺ mixed valence and to the relative ease of forming oxygen vacancies in the solid. The presence of cation vacancies in LaMnO_3.15 and the substitution of La³⁺ by alkali ions in LaMnO₃ increases the catalytic activity. The reduction of NO involves both molecular and dissociative adsorption of NO.     

Precise mass measurement of 68Se, a waiting-point nuclide along the rp process

Mass measurements of 68Ge, 68As, and 68Se have been obtained with the Canadian Penning Trap mass spectrometer. The results determine the mass excess of 68Se as -54 232(19) keV, the first measurement with a precision and reliability sufficient to address the light-curve and energy output of x-ray bursts as well as the abundances of the elements synthesized. Under typical conditions used for modeling x-ray bursts, 68Se is found to cause a significant delay in the rp process nucleosynthesis.     

Quality assurance and quality control for thermal/optical analysis of aerosol samples for organic and elemental carbon

Accurate, precise, and valid organic and elemental carbon (OC and EC, respectively) measurements require more effort than the routine analysis of ambient aerosol and source samples. This paper documents the quality assurance (QA) and quality control (QC) procedures that should be implemented to ensure consistency of OC and EC measurements. Prior to field sampling, the appropriate filter substrate must be selected and tested for sampling effectiveness. Unexposed filters are pre-fired to remove contaminants and acceptance tested. After sampling, filters must be stored in the laboratory in clean, labeled containers under refrigeration (<4 °C) to minimize loss of semi-volatile OC. QA activities include participation in laboratory accreditation programs, external system audits, and interlaboratory comparisons. For thermal/optical carbon analyses, periodic QC tests include calibration of the flame ionization detector with different types of carbon standards, thermogram inspection, replicate analyses, quantification of trace oxygen concentrations (<100 ppmv) in the helium atmosphere, and calibration of the sample temperature sensor. These established QA/QC procedures are applicable to aerosol sampling and analysis for carbon and other chemical components.