Ergodic theory of amenable semigroup actions

In this paper, among other things, we state and prove the mean ergodic theorem for amenable semigroup algebras.     

A novel synthetic route to 2-alkylpropane-1,3-sultones and its application to the synthesis of 2-alkyl derivatives of tramiprosate

A practical synthetic route to various 2-alkylpropane-1,3-sultones, the key intermediates for the preparation of 2-substituted homotaurines as analogs of tramiprosate, was developed.     

A portable positron accumulator for antihydrogen formation

A pulsed source of positrons has been developed which may be useful for antihydrogen ( ) formation because it is portable when compared to accelerator-based sources. This positron accumulator uses a Penning-style trap to collect moderated positrons from a radioactive source. The positron pulses may be emitted with repetition rates in the range of 50–1000 Hz, which is appropriate for production schemes involving laser-induced recombination. Bunching techniques may be used to vary the width of the positron pulses over the range 30–120 ns (FWHM) to match the width of the antiproton and/or laser pulses. The efficiency of the accumulator increases from ∼ 10% at 100 Hz to ∼ 50% at 1000 Hz. 250 Hz the efficiency is ∼ 25% and the accumulator has delivered up to 8 e⁺/pulse per mCi of positron activity. This translates into ∼ 1.2 × 10⁵ e⁺/pulse for a 100 Ci⁵⁸Co source.     

Immobilization of a nickel complex onto functionalized Fe3O4 nanoparticles: a green and recyclable catalyst for synthesis of 5-substituted 1H-tetrazoles and oxidation reactions

Research on Chemical Intermediates - In the present research, a magnetically recoverable catalyst was easily prepared by anchoring nickel onto the surface of organically modified magnetite...     

Silica-Supported MnII Sites as Efficient Catalysts for Carbonyl Hydroboration,Hydrosilylation, and Transesterification

Manganese, the third most abundant transition-metal element after iron and titanium, has recently been demonstrated to be an effective homogeneous catalyst in numerous reactions. Herein, the preparation of silica-supported Mn^II sites is reported using Surface Organometallic Chemistry (SOMC), combined with tailored thermolytic molecular precursors approach based on Mn₂[OSi(OtBu)₃]₄ and Mn{N(SiMe₃)₂}₂⋅THF. These supported Mn^II sites, free of organic ligands, efficiently catalyze numerous reactions: hydroboration and hydrosilylation of ketones and aldehydes as well as the transesterification of industrially relevant substrates.     

聚乙烯基吡啶高氯酸盐作为高效固体酸催化剂在无溶剂条件下催化醛化学选择性制备二乙酸盐(英文)

Poly(4-vinylpyridinium) perchlorate has been used as a supported,recyclable,environmentally-benign catalyst for the formation of acylals from aliphatic and aromatic aldehydes in good to excellent yields under solvent-free conditions.Notably,the reaction conditions were tolerant of ketones.This methodology offers several distinct advantages,including its operational simplicity and high product yield,as well as being green in terms of avoiding the use of toxic catalysts and solvents.Furthermore,the catalyst can be recovered and reused several times without any loss in its activity.     

1,3-Dibromo-5,5-dimethylhydantoin(DBH)/kaolin:An efficient reagent system for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes under solvent-free conditions

1,3-Dibromo-5,5-dimethylhydantoin,has been used as an efficient catalyst for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes in the presence of kaolin.All reactions are performed in the absence of solvent in relatively short reaction times in good to high yields.     

NH2SO3H and H6P2W18O62 · 18H2O-Catalyzed,Three-Component,One-Pot Synthesis of Benzo[c]acridine Derivatives

We report here two simple methods for the synthesis of benzo[c]acridine derivatives from three-component, one-pot condensation of 1-naphthylamine, dimedone, and a variety of substituted aldehydes in the presence of a catalytic amount of NH₂SO₃H or H₆P₂W₁₈O₆₂ · 18H₂O under solvent-free conditions at 120 °C or in refluxing ethanol.     

One-pot synthesis of 5-(furo[3,4-b]chromenyl)-5-hydroxybarbiturates via a three-component cascade reaction

A three-component domino reaction between a 3-formylchromone, an isocyanide, and 1,3-dimethylalloxan which affords novel 5-(furo[3,4-b]chromenyl)-5-hydroxybarbiturate derivatives is reported. The reaction sequence consists of an initial [4+1] cycloaddition followed by an activated electrophilic heteroaromatic substitution on the furan ring to afford the products. This novel cascade reaction sequence represents an atom-economic route to biologically interesting molecules.