Ultrasound-assisted synthesis of C-glycosides

A significant rate enhancement was observed in the preparation of allyl and allenyl-C-glycosides from glycosyl acetate or methyl O-glycoside precursors when ultrasound irradiation was employed as an energy source. The C-glycosides were obtained in 77-96% yields in <20 min using TMSOTf as promoter. These results show that sonication provides rapid and efficient access to useful C-glycoside-based building blocks.     

Combinatorially Factorizable Inverse Monoids

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Algorithms for the Laplace–Stieltjes Transforms of First Return Times for Stochastic Fluid Flows

We derive several algorithms, including quadratically convergent algorithms, which can be used to calculate the Laplace–Stieltjes transforms of the time taken to return to the initial level in the Markovian stochastic fluid flow model. We give physical interpretations of the algorithms and consider their numerical analysis. The numerical performance of the algorithms, which depends on the physical properties of the process, is discussed and illustrated with simple examples. Besides the powerful algorithms, this paper contributes interesting theoretical results. In particular, the methodology for constructing these algorithms is a valuable contribution to the theory of fluid flow models. Moreover, useful physical interpretations of the algorithms, and related expressions, given in terms of the fluid flow model, can assist in further analysis and help in a better understanding of the model. The authors would like to thank the Australian Research Council for funding this research through Discovery Project DP0770388.     

A convenient preparation of 3-methyl-3,4-dihydro-2(1H)-quinazolinone

3-Methyl-3,4-dihydro-2(1H)-quinazolinone ( 5 ) can be prepared in good yield and quality from o-nitrobenzyl chloride ( 1 ). The three-step sequence requires no purification of intermediates or final product.     

Psilocin analogs II. Synthesis of 3-[2-(dialkylamino)ethyl]-, 3-[2-(N-methyl-N-alkylamino)ethyl]-, and 3-[2-(cycloalkylamino)ethyl]indol-4-ols

Structural alteration of the N^b-substituents of psilocin (3-[2-dimethylamino)ethyl]indol-4-ol) ( 12a ) has led to a number of compounds containing known pharmacophoric groups. Further, it is hoped that the subtle changes in the nature of these substituents may lead to a clearer understanding of the structure-activity relationships of the 4-hydroxytryptamine hallucinogens.     

The 3ν1 + ν3 vibrational overtone spectrum of CH4

The 3 ν₁ + ν₃ vibrational overtone spectrum of ¹³CH₄ is recorded under Doppler-limited resolution conditions using a titanium sapphire laser-based photoacoustic spectrometer. Data at two temperatures, 100 and 293 K, are presented. The observed spectral congestion is qualitatively similar to that observed for ¹²CH₄, but the detailed ro-vibrational structure of the two isotope variants is completely different. The data reflect the complicating influences of tetrahedral fine structure and vibrational state mixing.     

Double resonance ejection in a micro ion trap mass spectrometer

Ion ejection from a cylindrical micro ion trap by resonance excitation of the secular motion is observed to be strongly dependent on the frequency of the secular motion at resonance. Both the intensity of the ion signal and the mass resolution of the resulting mass spectrum are increased when the ion secular frequency is approximately that of a nonlinear resonance of the trap. The resonances are attributed to electrical as well as geometrical considerations.     

A systematic approach to the study of multicomponent polymerization kinetics: The butyl acrylate/methyl methacrylate/vinyl acetate example. IV. Optimal Bayesian design of emulsion terpolymerization experiments in a pilot plant reactor

A systematic study of the terpolymerization of butyl acrylate/methyl methacrylate/vinyl acetate (BA/MMA/VAc) is being conducted. In this stage of the study, emulsion terpolymerizations were performed in a 5 L stainless steel pilot plant reactor. The experimental trials were of the two-level factorial type and were designed optimally using a Bayesian method. The design procedure allowed us to improve our knowledge about the process using our prior knowledge and our subjective judgement. The polymers produced were characterized for conversion, composition, molecular weight, and particle size. The Bayesian design of experiments is shown to have several advantages over conventional factorial designs. © 1996 John Wiley & Sons, Inc.     

Decomposition of the lattice of pseudovarieties of finite semigroups induced by bands

It has been shown by the authors that the mapping,where B is the pseudovariety of finite bands, is a complete retraction of the lattice L(F) of pseudovarieties of finite semigroups onto the lattice of pseudovarieties of bands. It follows that the classes of the induced congruence on L(F), or on the lattice of subpseudovarieties L(W) for any subpseudovariety W of F, are intervals. In this paper we solve the membership problem for the upper limit of the classes of restricted to L(W) for various , including F itself, and provide bases of pseudoidentities for certain cases. Received April 7, 1999; accepted in final form April 30, 2000.