Thermodynamic properties of oxygen compounds I. Vinyl acetate

A complete vibrational assignment is made and ideal gas thermodynamic properties of vinyl acetate have been reported from 100–1500 K. Internal rotational contributions have been calculated using Pitzer and Gwinn's tables.     

A relative organolithium stability scale derived from tin-lithium exchange equilibria. Substituent effects on the stability of alpha-oxy- and alpha-aminoorganolithium compounds

Quantitative thermodynamic stability scales of organolithium compounds can be derived from measurements of tin-lithium exchange equilibria. A DeltaG(eq) scale of alpha-oxy- and alpha-aminoorganolithium compounds was established, and quantitative stabilization effects of O-alkyl, O-alkoxyalkyl, O-carbamoyl, N-carbamoyl, and O-carbonyl groups of the alpha-carbanion are presented. It has been found that an alpha-oxycarbanion is far better stabilized by a carbonyl group as the O-substituent than by an alkyl or alkoxyalkyl group, while the anion-stabilizing effects of the different O-carbonyl substituents are comparable. An N-carbamoyl group was found to have a somewhat higher stabilizing effect than its O-carbamoyl counterpart. NMR data are presented that show that benzylic N- or O-substituted carbanions have highly planarized structures where the negative charge is highly delocalized. The stability data obtained from the tin-lithium exchanges can be easily converted into "effective pK" data that are useful for predicting the acid-base behavior of this type of organolithium species.     

Essential Spanning Forests and Electrical Networks on Groups

Let be a Cayley graph of a finitely generated group G. Subgraphs which contain all vertices of , have no cycles, and no finite connected components are called essential spanning forests. The set of all such subgraphs can be endowed with a compact topology, and G acts on by translations. We define a uniform G-invariant probability measure on show that is mixing, and give a sufficient condition for directional tail triviality. For non-cocompact Fuchsian groups we show how can be computed on cylinder sets. We obtain as a corollary, that the tail -algebra is trivial, and that the rate of convergence to mixing is exponential. The transfer-current function (an analogue to the Green function), is computed explicitly for the Modular and Hecke groups.     

Redox chemistry of guanine and 8-oxyguanine and a comparison of the peroxidase-catalyzed and electrochemical oxidation of 8-oxyguanine

The electrochemical oxidation of guanine and 8-oxyguanine has been studied over a wide pH range in aqueous solution. Guanine is initially oxidized in a     

Probabilistic modeling of computer system availability

System availability is becoming an increasingly important factor in evaluating the behavior of commercial computer systems. This is due to the increased dependence of enterprises on continuously operating computer systems and to the emphasis on fault-tolerant designs. Thus, we expect availability modeling to be of increasing interest to computer system analysts and for performance models and availability models to be used to evaluate combined performance/availability (performability) measures. Since commercial computer systems are repairable, availability measures are of greater interest than reliability measures. Reliability measures are typically used to evaluate nonrepairable systems such as occur in military and aerospace applications. We will discuss system aspects which should be represented in an availability model; however, our main focus is a state of the art summary of analytical and numerical methods used to solve computer system availability models. We will consider both transient and steady-state availability measures and for transient measures, both expected values and distributions. We are developing a program package for system availability modeling and intend to incorporate the best solution methods.