10,391 research outputs found
Determination of nitrogen in titanium nitride
Quantitative determination of nitrogen in titanium nitride involves dissolution of TiN in 10M hydrofluoric acid containing an oxidant. Released nitrogen is determined as ammonia. Best oxidizers are ferric chloride, potassium iodate, and potassium dichromate
Small numbers matching markets: Unstable and inefficient due to over-competition?
The extant literature on matching markets assumes ordinal preferences for matches, while bargaining within matches is mostly excluded. Central for this paper, however, is the bargaining over joint profits from potential matches. We investigate, both theoretically and experimentally, a seemingly simple allocation task in a 2x2 market with repeated negotiations. More than 75% of the experimental allocations are unstable, and 40% of the matches are inefficient (in cases where inefficiency is possible). By defining the novel concept 'altruistic core', we can explain the occurrence of inefficient matches as well as the significant behavioral differences among our six treatments. --matching market,price negotiation,optimal allocation,altruism
Superfluid gap formation in a fermionic optical lattice with spin imbalanced populations
We investigate the attractive Hubbard model in infinite spatial dimensions at
quarter filling. By combining dynamical mean-field theory with continuous-time
quantum Monte Carlo simulations in the Nambu formalism, we directly deal with
the superfluid phase in the population imbalanced system. We discuss the low
energy properties in the polarized superfluid state and the pseudogap behavior
in the vicinity of the critical temperature.Comment: 4 pages, 1 figure, To appear in J. Phys.: Conf. Ser. for SCES201
Kinetics of copper ion absorption by cross-linked calcium polyacrylate membranes
The absorption of copper ions from aqueous copper acetate solutions by cross-linked calcium acrylate membranes was found to obey parabolic kinetics similar to that found for oxidation of metals that form protective oxide layers. For pure calcium polyacrylate membranes the rate constant was essentially independent of copper acetate concentration and film thickness. For a cross-linked copolymer film of polyvinyl alcohol and calcium polyacrylate, the rate constant was much greater and dependent on the concentration of copper acetate. The proposed mechanism in each case involves the formation of a copper polyacrylate phase on the surface of the membrane. The diffusion of the copper ion through this phase appears to be the rate controlling step for the copolymer film. The diffusion of the calcium ion is apparently the rate controlling step for the calcium polyacrylate. At low pH, the copper polyacrylate phase consists of the normal copper salt; at higher pH, the phase appears to be the basic copper salt
Binary Stars as the Source of the Far-UV Excess in Elliptical Galaxies
The discovery of an excess of light in the far-ultraviolet (UV) spectrum in
elliptical galaxies was a major surprise in 1969. While it is now clear that
this UV excess is caused by an old population of hot helium-burning stars
without large hydrogen-rich envelopes rather than young stars, their origin has
remained a mystery. Here we show that these stars most likely lost their
envelopes because of binary interactions, similar to the hot subdwarf
population in our own Galaxy. This has major implications for understanding the
evolution of the UV excess and of elliptical galaxies in general. In
particular, it implies that the UV excess is not a sign of age, as had been
postulated previously, and predicts that it should not be strongly dependent on
the metallicity of the population.Comment: Proceedings of Puerto Vallarta 07, "New Quests in Stellar
Astrophysics. II. The Ultraviolet Properties of Evolved Stellar Populations",
6 pages, 2 figures. A much better version of Figure 1 can be obtained on
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Functioning of inorganic/organic battery separators in silver-zinc cells
The results of three experimental studies related to the inorganic/organic battery separator operating mechanism are described: saponification of the plasticizer, resistivity of the simulated separators, and zincate diffusion through the separators. The inorganic/organic separator appears to be a particular example of a general class of ionic conducting films composed of inorganic fillers and/or substrates bonded together by an organic polymer containing an incompatible plasticizer that may be leached by the electrolyte. The I/O separator functions as a microporous film of varying tortuosity with essentially no specific chemical inhibition to zincate diffusion
Radiochemical synthesis of pure anhydrous metal halides
Method uses radiation chemistry as practical tool for inorganic preparations and in particular deposition of metals by irradiation of their aqueous metal salt solutions with high energy electrons. Higher valence metal halide is dissolved in organic liquid and exposed to high energy electrons. This causes metal halide to be reduced to a lower valence metal halide
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