In situ high-resolution transmission electron microscopy synthesis observation of nanostructured carbon coated LiFePO4

In situ high-resolution transmission electron microscopy (HRTEM) studies of the structural transformations that occur during the synthesis of carbon-coated LiFePO₄ (C-LiFePO₄) and heat treatment to elevated temperatures were conducted in two different electron microscopes. Both microscopes have sample holders that are capable of heating up to 1500 °C, with one working under high vacuum and the other capable of operating with the sample surrounded by a low gaseous environment. The C-LiFePO₄ samples were prepared using three different compositions of precursor materials with Fe(0), Fe(II) or Fe(III), a Li-containing salt and a polyethylene-block-poly(ethylene glycol)-50% ethylene oxide or lactose. The in situ TEM studies suggest that low-cost Fe(0) and a low-cost carbon-containing compound such as lactose are very attractive precursors for mass production of C-LiFePO₄, and that 700 °C is the optimum synthesis temperature. At temperatures higher than 800 °C, LiFePO₄ has a tendency to decompose. The same in situ measurements have been made on particles without carbon coat. The results show that the homogeneous deposit of the carbon deposit at 700 °C is the result of the annealing that cures the disorder of the surface layer of bare LiFePO₄. Electrochemical tests supported the conclusion that the C-LiFePO₄ derived from Fe(0) is the most attractive for mass production.     

A fuzzy screening model for multiple attribute decision-making

A method for the screening of multiple attribute decision-making problems is presented. The model assists the decision-maker in eliminating inferior alternatives and insignificant attributes prior to a detailed evaluation. A preliminary evaluation of the alternatives provides the information necessary for the reduction of the decision problem. The procedure calculates maximum preference factors on which the decision-maker can base his screening decisions. These factors assess the role of alternatives in the final ranking by estimating their potential to become superior to other alternatives. Since screening tasks are carried out early in decision-making, the information available is generally uncertain. Uncertainty is represented in the model using fuzzy sets. This framework permits the handling of both imprecise and precise (crisp) estimates of impacts and provides a possibil-istic assessment of the risk associated with screening decisions.     

Taming reactive phenol tautomers and o-quinone methides with transition metals: a structure-reactivity relationship

Quinone methides act as important intermediates in organic syntheses, as well as in chemical and biological processes; however, examples of such isolated species are scarce as a result of their high reactivity. Phenol tautomers (keto form of phenol) are also important intermediates in several organic and organometallic reactions; nevertheless, isolated complexes are rare. This Account reviews the recent progress on the synthesis and reactivity of iridium and rhodium o-quinone methide complexes as well as on iridium-mediated ortho functionalization of phenols. This reaction was at the origin of the discovery of a general synthetic procedure to prepare the first metal-stabilized o-quinone methide.     

Low-dissipation and low-dispersion fourth-order Runge–Kutta algorithm

An optimized explicit low-storage fourth-order Runge–Kutta algorithm is proposed in the present work for time integration. Dispersion and dissipation of the scheme are minimized in the Fourier space over a large range of frequencies for linear operators while enforcing a wide stability range. The scheme remains of order four with nonlinear operators thanks to the low-storage algorithm. Linear and nonlinear propagation problems are finally solved to illustrate the accuracy of the present Runge–Kutta scheme.     

A Survey of Desynchronization in a Polychronous Model of Computation

The synchronous hypothesis arose in the late Eighties as a conceptual framework for the computer-aided design of embedded systems. Along with this framework, the issue of desynchronization was simultaneously raised as the major topic of mapping the ideal communication and computation model of synchrony on realistic and distributed computer architectures.The aim of the present article is to survey the development of this topics in the particular yet promising model of one of the prominent environments that were build along these principles: Signal and its polychronous (synchronous multi-clocked) model of computation, before to give some hints and ideas about ongoing research addressing this issue.     

Changes in land surface temperatures and NDVI values over Europe between 1982 and 1999

We used land surface temperature (LST) algorithms and NDVI values to estimate changes in vegetation in the European continent between 1982 and 1999 from the Pathfinder AVHRR Land (PAL) dataset. These two parameters are monitored through HANTS (Harmonic ANalysis of Time Series) software, which allows the simultaneous observation of mean value, first harmonic amplitude and phase behaviors in the same image. These results for each complete year of data show the effect of volcanic aerosols and orbital drift on PAL data. Comparison of time series of HANTS cloud-free time series with the original time series for various land cover proves that this software is useful for LST analysis, although primarily designed for NDVI applications. Comparison of yearly averages of HANTS LST over the whole Europe with air temperature confirms the validity of the results. Maps of the evolution for both parameters between periods 1982/1986 and 1995/1999 have been elaborated: NDVI data show the well confirmed trend of increase over Europe (up to 0.1 in NDVI), Southern Europe seeing a decrease in NDVI (− 0.02). LST averages stay stable or slightly decrease (up to − 1.5 K) over the whole continent, except for southern areas for which the increase is up to 2.5 K. These results evidence that arid and semi-arid areas of Southern Europe have become more arid, the rest of Europe seeing an increase in its wood land proportion, while seasonal amplitude in Northern Europe has decreased.