Me?apparate

Ohne Zusammenfassung     

A taylor weak-statement algorithm for hyperbolic conservation laws

Finite element analysis, applied to computational fluid dynamics (CFD) problem classes, presents a formal procedure for establishing the ingredients of a discrete approximation numerical solution algorithm. A classical Galerkin weak-statement formulation, formed on a Taylor series extension of the conservation law system, is developed herein that embeds a set of parameters eligible for constraint according to specification of suitable norms. The derived family of Taylor weak statements is shown to contain, as special cases, over one dozen independently derived CFD algorithms published over the past several decades for the high speed flow problem class. A theoretical analysis is completed that facilitates direct qualitative comparisons. Numerical results for definitive linear and non-linear test problems permit direct quantitative performance comparisons.     

Kinetics of Oxidation of L‐Cysteine by trans‐ and cis‐CoIII and FeIII Complexes based on α‐ and γ‐Diimine Schiff Base Ligands

Kinetics of oxidation of L ‐cysteine by Co^III and Fe^III complexes based on α‐ and γ‐diimine Schiff base ligands were studied in aqueous solution. Pairs of trans and cis isomers of the metal complexes were used in the studies. Kinetic measurements were performed at 25 °C and constant pH and ionic strength under pseudo‐first order condition, in which the concentration of cysteine was around two orders of magnitude greater than that of the metal complex. The observed rate constant was obtained by following the change in absorbance of the reaction mixture with time at a predetermined wavelength. The overall rate constant and order of the reaction with respect to cysteine and metal complex were determined. For both metal ions studied, the oxidation rate constant for the trans isomer was higher than that for the cis isomer. This was attributed to the contribution of the steric factor and the trans effect. The effects of substituents and the nature of the metal ion on the reaction rate are discussed.     

A stereoselective cyclisation cascade mediated by SmI2–H2O: synthetic studies towards stolonidiol

A cascade reaction involving sequential conjugate reduction, stereoselective aldol cyclisation and chemoselective lactone reduction mediated by SmI₂–H₂O provides access to a cyclopentanol bearing two vicinal quaternary stereocentres with good stereocontrol. The functionalised cyclopentanol product has been converted to a key intermediate in ongoing asymmetric studies towards stolonidiol.     

Corner ion,edge-center ion,and face-center ion Madelung expressions for sodium chloride

Building on work of Tyagi (Progr Theor Phys 114(3):517–521, 2005), we present expressions for calculating the corner ion, edge-center ion, and face-center ion Madelung constants for bulk sodium chloride crystals.     

Luminescent Carbon Nanodots: Emergent Nanolights

Similar to its popular older cousins the fullerene, the carbon nanotube, and graphene, the latest form of nanocarbon, the carbon nanodot, is inspiring intensive research efforts in its own right. These surface‐passivated carbonaceous quantum dots, so‐called C‐dots, combine several favorable attributes of traditional semiconductor‐based quantum dots (namely, size‐ and wavelength‐dependent luminescence emission, resistance to photobleaching, ease of bioconjugation) without incurring the burden of intrinsic toxicity or elemental scarcity and without the need for stringent, intricate, tedious, costly, or inefficient preparation steps. C‐dots can be produced inexpensively and on a large scale (frequently using a one‐step pathway and potentially from biomass waste‐derived sources) by many approaches, ranging from simple candle burning to in situ dehydration reactions to laser ablation methods. In this Review, we summarize recent advances in the synthesis and characterization of C‐dots. We also speculate on their future and discuss potential developments for their use in energy conversion/storage, bioimaging, drug delivery, sensors, diagnostics, and composites.