Synthése d'héterocycles. XX. Reaction du malononitrile avec quelques cinnamonitriles

Reaction of cinnamonitriles with malononitrile, in methanolmethoxide, yield dihydropyridines, which by aromatisation give pyridines. Pyridine is directly obtained when p-nitrocinnamonitrile is used     

Synthesis of heterocyclic compounds. XXIV. Synthesis of pyridines from β-substituted α-phenylacrylonitriles

The reaction of malononitrile with α-phenylcinnamonitriles in ethanolic sodium ethanethiolate is studied as a convenient route to 2-amino-4-aryl-5-cyano-6-ethylthio-3-phenyl-3,4-dihydropyridines ( 5 ) and the corresponding pyridines 6 . From the study of the structure of 5a (Ar = Ph) we can conclude that this cyclization reaction proceeds via a site-selective addition of the ethanethiolate to the cyano group i of the 1,3-tricarbonitrile ( 2 ).     

Temperature effect on electrochemical properties of lithium manganese phosphate with carbon coating and decorating with MWCNT for lithium-ion battery

Journal of Solid State Electrochemistry - The increasing demands for higher energy density and higher power capacity of Li-ion secondary batteries have led to a search for electrode materials whose...     

Robust pair‐copula based forecasts of realized volatility

A useful application for copula functions is modeling the dynamics in the conditional moments of a time series. Using copulas, one can go beyond the traditional linear ARMA (p,q) modeling, which is solely based on the behavior of the autocorrelation function, and capture the entire dependence structure linking consecutive observations. This type of serial dependence is best represented by a canonical vine decomposition, and we illustrate this idea in the context of emerging stock markets, modeling linear and nonlinear temporal dependences of Brazilian series of realized volatilities. However, the analysis of intraday data collected from e‐markets poses some specific challenges. The large amount of real‐time information calls for heavy data manipulation, which may result in gross errors. Atypical points in high‐frequency intraday transaction prices may contaminate the series of daily realized volatilities, thus affecting classical statistical inference and leading to poor predictions. Therefore, in this paper, we propose to robustly estimate pair‐copula models using the weighted minimum distance and the weighted maximum likelihood estimates (WMLE). The excellent performance of these robust estimates for pair‐copula models are assessed through a comprehensive set of simulations, from which the WMLE emerged as the best option for members of the elliptical copula family. We evaluate and compare alternative volatility forecasts and show that the robustly estimated canonical vine‐based forecasts outperform the competitors. Copyright © 2013 John Wiley & Sons, Ltd.     

Selecting green suppliers based on GSCM practices: Using fuzzy TOPSIS applied to a Brazilian electronics company

Due to an increased awareness and significant environmental pressures from various stakeholders, companies have begun to realize the significance of incorporating green practices into their daily activities. This paper proposes a framework using Fuzzy TOPSIS to select green suppliers for a Brazilian electronics company; our framework is built on the criteria of green supply chain management (GSCM) practices. An empirical analysis is made, and the data are collected from a set of 12 available suppliers. We use a fuzzy TOPSIS approach to rank the suppliers, and the results of the proposed framework are compared with the ranks obtained by both the geometric mean and the graded mean methods of fuzzy TOPSIS methodology. Then a Spearman rank correlation coefficient is used to find the statistical difference between the ranks obtained by the three methods. Finally, a sensitivity analysis has been performed to examine the influence of the preferences given by the decision makers for the chosen GSCM practices on the selection of green suppliers. Results indicate that the four dominant criteria are Commitment of senior management to GSCM; Product designs that reduce, reuse, recycle, or reclaim materials, components, or energy; Compliance with legal environmental requirements and auditing programs; and Product designs that avoid or reduce toxic or hazardous material use.     

Gaps in the poset of projections in the Calkin algebra

We study the gap structure of the partial order of projections of the Calkin algebra of a complex, separable, infinite-dimensional Hilbert space. We prove the existence of an analytic Hausdorff gap in this partial order. As a consequence we obtain that under Todorcevic’s Axiom and MA the gap spectrum of P(C(H)) is strictly bigger than the gap spectrum of P(ω)/Fin.     

Compact,convex sets in R n and a new banach lattice. II.- Application: An approximation problem.

We develop a calculus structure in the Banach lattice introduced in a preceding paper, having in mind an approximation problem appearing in non-smooth optimization. We show that the essential results depend as much on the order structure as on the analytical one.     

Experimental study of transition to turbulence of a round thermal plume by ultrasound scattering

In this study, we carried out the characterization of the transition to turbulence of a thermal pure plume by using ultrasound scattering. For this, the position, amplitude and broadening of the scattering peak are analyzed. The technique is based upon the scattering of an ultrasound wave coupling with an unstable flow. The coupling between the acoustic mode with both vorticity and entropy modes is derived from non-linear terms of Navier–Stokes and energy equations. When the scattering mechanism occurs, the characteristic length scale of the flow structure under observation is comparable with the wavelength of incoming sound. Thus, the flow can be probed at different length scales by only changing the frequency of incoming sound. The thermal plume rises from a heated disk immersed into a quiescent medium and can reach transition and fully turbulent regimes. Criteria allowing the identification of both the beginning and the end of transition are derived from the results. The characteristics of the scattering process show evidence that allows us to discern the beginning of transition. The analysis of the amplitude of the scattering peak revealed a homogeneous behavior and led us to think of a possible principle of similarity. The evolution of both thermal and velocity fluctuations has made it possible to establish the limits of both the beginning and the end of transition, in terms of local Grashof number Gr_z and position of the measurement zone z/D. The limits for transition reported in this work are comparable in its magnitude order with those of the literature. It was verified that thermal and velocity transition are phenomena that begin and finish almost simultaneously.     

A Look at BMOϕ(ω) through Carleson Measures

As Fefferman and Stein showed, there is a tight connection between Carleson measures and BMO functions. In this work we extend this type of results to the more general scope of the BMO_ϕ(ω) spaces. As a byproduct a weighted version of the Triebel-Lizorkin space is introduced, which turns out to be isomorphic to BMO(ω) as in the unweighted case.