Tetronamides as latent acyclic vinylogous amides in formal aza-[3 + 3] cycloaddition reactions with alpha,beta-unsaturated iminium salts. An unexpected rearrangement and an approach to synthesis of substituted piperidines

A detailed account regarding formal aza-[3 + 3] cycloaddition reactions of tetronamides with alpha,beta-unsaturated iminium salts is described here. This investigation uncovers regioisomeric cycloadducts that were not found in previous studies involving this formal cycloaddition and an unexpected rearrangement that led to pyridines and dihydropyridines. Both stereochemical and regiochemical issues raised in this study provide further mechanistic insights into this cycloaddition. With careful control of reaction temperatures, the desired formal cycloadducts are obtained. Ensuing transformation of these cycloadducts into functionalized piperidines establishes the concept of employing tetronamides as latent acyclic vinylogous amides for the formal aza-[3 + 3] cycloaddition.     

The use of a germene for the synthesis of esters of alpha-germyl-substituted alpha-amino acid and alpha-aminophosphonic acid

The first alpha-germyl-substituted alpha-amino ester and alpha-germyl-substituted alpha-aminophosphonic ester have been synthesized by a one-pot reaction between the germene Mes2Ge=CR2 (CR2 = fluorenylidene) and the iminoester or iminophosphonate Ph(H)C=NCH2-Y (Y = COOMe, P(O)(OEt)2).     

Fast randomization of an electron gas by trapped electro-acoustic waves

Summary This paper presents a simplified theoretical model for a phenomenon of fast randomization of an electron gas, investigated experimentally in this laboratory. It is assumed that a certain region in constricted electrical discharges, called plasma sac can become the siege of trapped electro-acoustic waves generated by a beam-plasma interaction. The interaction between those waves and the electron gas is treated by a pseudo collisional method, leading to a generalization of Boltzmann's H theorem. The velocity distribution which is essentially Maxwellian with a significant deficiency in the fast electron tail, is deduced.     

Modelling the Process of Multiattribute Choice

In most of the multiattribute utility models it is assumed that the analytical forms of partial and overall utility functions are known, and hence the problem becomes one of estimating the values of model parameters. This assumption is rather restrictive since one may not possess prior knowledge as to the analytical forms of such functions. The present paper is an attempt to eliminate some of the shortcomings of the existing models by proposing two new formulations of the multiattribute choice problem without a priori limitation to any strict form of partial utility function.     

Designing global supply networks for conflict or disaster support: the case of the Canadian Armed Forces

In order to fulfil Canada’s international disaster relief, humanitarian assistance, peacekeeping and peace enforcement roles, the Canadian Forces (CF) rely on a supply network to deploy and sustain its overseas missions. Warehousing, maintenance, transhipment and transportation activities are required to support missions. Currently, the CF supply network does not incorporate any permanent overseas depots. Since international needs and Canada’s roles have significantly evolved during the last decade, and given that supply network efficiency and robustness are critical for missions’ success, reengineering the CF supply network to consider the incorporation of permanent international prepositioning depots has become an important issue. This paper proposes an activity-based stochastic programming model to optimise the CF overseas supply network. It also shows how the model proposed can be used to improve the global reach of the CF.     

Well-posedness of a stochastic phase-field problem with multiplicative noises

In this paper, we prove the existence and uniqueness of the solution of a stochastic phase-field problem with multiplicative noises. Phase-field models are typically used to describe melting and solidification processes. We consider here the case of multiplicative noises induced by a Q-Brownian motion.     

Rational polynomial representation of ribonucleotide reductase activity

Background  

Recent data suggest that ribonucleotide reductase (RNR) exists not only as a heterodimer R1₂R2₂ of R1₂ and R2₂ homodimers, but also as tetramers R1₄R2₄ and hexamers R1₆R2₆. Recent data also suggest that ATP binds the R1 subunit at a previously undescribed hexamerization site, in addition to its binding to previously described dimerization and tetramerization sites. Thus, the current view is that R1 has four NDP substrate binding possibilities, four dimerization site binding possibilities (dATP, ATP, dGTP, or dTTP), two tetramerization site binding possibilities (dATP or ATP), and one hexamerization site binding possibility (ATP), in addition to possibilities of unbound site states. This large number of internal R1 states implies an even larger number of quaternary states. A mathematical model of RNR activity which explicitly represents the states of R1 currently exists, but it is complicated in several ways: (1) it includes up to six-fold nested sums; (2) it uses different mathematical structures under different substrate-modulator conditions; and (3) it requires root solutions of high order polynomials to determine R1 proportions in mono-, di-, tetra- and hexamer states and thus RNR activity as a function of modulator and total R1 concentrations.