The Algebraic K-Theory of Operator Algebras

We the study the algebraic K-theory of C *-algebras, forgetting the topology. The main results include a proof that commutative C*-algebras are K-regular in all degrees (that is, all theirN ^T K _iand extensions of the Fischer-Prasolov Theorem comparing algebraic and topological K-theory with finite coefficients.     

On the probability distributions of relaxation times in glasses

The scale of relaxation times in glasses has led to generalizations of the Drude model of the dielectric function in terms of an integral, containing a Drude kernel and a probability distribution. This integral equation is solved by a Mellin or a Stieltjes transform. Beyond known results, we obtain the probability distribution of the Havriliak-Negami dielectric function. Even more general classes of dielectric models can be dealt with, using Mellin's transform. They may serve as checks for numerical procedures applied to the underlying ill-posed problem, if experimental data for the dielectric function are used. Received: 2 February 1998 / Accepted: 17 March 1998     

Synthesis of novel deoxynucleoside S-methylphosphonic acids using S-(diisopropylphosphonomethyl)isothiouronium tosylate, a new equivalent of mercaptomethylphosphonate

The synthesis of the novel nucleotide analogues 5'-deoxynucleoside-5'-S-methylphosphonates, starting from 5'-deoxy-5'-haloribonucleosides, 5'-O-tosylribonucleosides, and 2'-O-triflylnucleosides, is described. The phosphonothiolation of these compounds was achieved using S-(diisopropylphosphonomethyl)isothiouronium tosylate, a new, odourless, and efficient equivalent of mercaptomethylphosphonate. The thiolate anion of mercaptomethylphosphonate was generated in situ from the isothiouronium salt in both protic and aprotic solvents using two equivalents of sodium iso-propoxide. The prepared nucleoside 5'-S-methylphosphonates were deprotected, and the free phosphonic acids were transformed into diphosphoryl derivatives (the NTP analogues). Both mononucleotides and NTP analogues were studied as substrates/inhibitors of several enzymes that are involved in the nucleoside/nucleotide metabolism.     

Determination of pK(a) values of N-heterocyclic bases by fluorescence spectrophotometry

Fluorimetry is a relatively fast and accurate means of determining the dissociation constants of sparingly soluble heterocyclic bases. Complications can arise, however, from the dependence of fluorescence on excited-state as well as ground-state acid-base chemistry. Several approaches to circumventing or compensating for this difficulty are discussed. To demonstrate the utility of the methods, the pK(a), values of the conjugate acids of two bases are evaluated by the methods described.     

UV-induced Coulomb crystallization of dust grains in high-pressuregas

A scheme for forming a Coulomb lattice of positively charged dust grains in a high-pressure (P>torr) gas is discussed theoretically. The grains are charged positively by photoemission in the presence of a flux of ultraviolet (UV) photons with energy larger than the work function of the grains, but lower than the ionization potential of the background gas. Methods for levitating and containing the dust using photophoretic forces (both UV and non-UV), gas drag, and electrostatic forces are considered     

Proceedings of the conference on organic chemistry at clusters and surfaces

The Proceedings of the Conference on Organic Chemistry at Clusters and Surfaces will comprise Volume 3, Number 3 (September 1992); Volume 3, Number 4 (December 1992); and Volume 4, Number 1 (March 1993).