Towards Polyoxometalate‐Cluster‐Based Nano‐Electronics

We explore the concept that the incorporation of polyoxometalates (POMs) into complementary metal oxide semiconductor (CMOS) technologies could offer a fundamentally better way to design and engineer new types of data storage devices, due to the enhanced electronic complementarity with SiO₂, high redox potentials, and multiple redox states accessible to polyoxometalate clusters. To explore this we constructed a custom‐built simulation domain bridge. Connecting DFT, for the quantum mechanical modelling part, and mesoscopic device modelling, confirms the theoretical basis for the proposed advantages of POMs in non‐volatile molecular memories (NVMM) or flash‐RAM.     

Implicit function theorems for generalized equations

We show that Lipschitz and differentiability properties of a solution to a parameterized generalized equation 0 f(x, y) + F(x), wheref is a function andF is a set-valued map acting in Banach spaces, are determined by the corresponding Lipschitz and differentiability properties of a solution toz g(x) + F(x), whereg strongly approximatesf in the sense of Robinson. In particular, the inverse map (f + F)^–1 has a local selection which is Lipschitz continuous nearx ₀ and Fréchet (Gateaux, Bouligand, directionally) differentiable atx ₀ if and only if the linearization inverse (f (x ₀) + f (x₀) (× – x₀) + F(×))^–1 has the same properties. As an application, we study directional differentiability of a solution to a variational inequality.This work was supported by National Science Foundation Grant Number DMS 9404431.     

Effect of calcination temperature on the properties of industrial V2O5-TiO2 (anatase) catalysts in methanol oxidation

The properties of the catalysts for partial oxidation of o-xylene depend on the structure of the supported vanadium sites. The structure itself is strongly dependent on the calcination temperature of the catalyst at which thermal deposition of the metal oxide on the oxide support takes place. We have investigated the effect of calcination temperature on the activity and selectivity of industrial V₂O₅-TiO₂ (anatase) supported catalysts designed for partial oxidation of o-xylene in their application to methanol oxidation.This revised version was published online in December 2005 with corrections to the Cover Date.     

A proof of the Lyusternik–Graves theorem

In this paper, we give a new proof of the Lyusternik–Graves theorem, based on an intermediate result regarding linear openness inspired by works of Frankowska and Ursescu.     

Kinetics and mechanism of the cyclization of omega-(p-nitrophenyl)-hydantoic acid amides: steric hindrance to proton transfer causes a 10(4)-fold change in rate

The pH-rate profiles for the cyclization of primary 2,3-dimethyl and 2,2,3-trimethyl-hydantoinamides (2-UAm and 3-UAm respectively) differ strikingly from those for the cyclizations of the corresponding N-methylated amides 2-MUAm and 3-MUAm; which are dominated by the water reaction, spanning some 6 pH units. For the cyclization of UAm the plateau extends over no more than two pH units. The difference is due to the slower base-catalyzed cyclization of the N-methylamides. The solvent kinetic isotope effect for this hydroxide-catalyzed reaction is close to 1.2, consistent with a slow protonation by water of the amino-group of the negatively charged tetrahedral intermediate. General base catalysis was observed with bases of pKBH up to 8. The Br?nsted beta are compatible with a hydrogen bonding mechanism for the GBC. In the gem-dimethyl compounds 3 the leaving group is flanked by substituents on both sides. The N-methyl group in 3-MUAm hinders frontal access of the proton, causing a 14000 fold decrease in rate. This is only 3800 fold in the compound with one methyl group at position 2.     

Acid catalyzed intramolecular attack of β‐phenylthioureido group on amide function. Parallel formation of thiodihydrouracil and 4‐iminothiodihydrouracil. Different pathways in the Edman degradation reaction in the formation of six‐ versus five‐membered cyclic intermediates

Contrary to the cleavage of α‐phenylthioureido peptides 1 proceeding through intermediate 2‐anilinothiazolinone 2 , the b‐analog cis‐2‐(3‐phenylthioureido)cyclopentane‐carboxamide 5 forms transiently 4‐imino‐2‐thioxopyrimidine 6 . Monitoring amide cyclization and hydrolysis of iminopyrimidine 6 in acid by UV showed that an equilibrium between 5 and 6 was reached followed by slower conversion of both compounds into 2‐oxo‐4‐thioxopyrimidine 7 . Both processes were characterized by isosbestic points, the first due to parallel conversion of 5 into 6 and 7 (or 6 into 5 and 7 ) at a constant ratio while the second identical for both reactants – to conversion of equilibrated 5 and 6 into 7 . The special isosbestic points allowed the determination of the individual constants of Scheme 2. Further confirmation was obtained from NMR product analysis and following the cyclization of amide 5 in DMSO:DCl. Product 2‐oxo‐4‐ thioxopyrimidine 7 hydrolyzed reversibly to thioureido acid 8 . The cyclization rate of 8 allowed the participation of 6‐oxothiazine 10 formed by sulfur attack to be excluded. The absence of sulfur attack in the six‐membered case is explained by the longer C? S bond bringing about greater bond angle strain at the tetrahedral ring atoms due to the geometrical characteristics of five‐ and six‐membered rings with planar segments. The cyclizations of amide 5 to iminopyrimidine 6 and to thiodihydrouracil 7 are first order in [H⁺], while the reactions of protonated imine 6 H⁺ are zero order to amide and ?1 to thiodihydrouracil. The reaction orders can be reconciled by assuming a rate determining proton transfer from the tetrahedral intermediate in amide cyclization. Copyright © 2007 John Wiley & Sons, Ltd.     

Transition metal ions-doped polyaniline/graphene oxide nanostructure as high performance electrode for supercapacitor applications

Journal of Solid State Electrochemistry - Polyaniline/graphene oxide (PANI/GO) co-doped with Zn2+ and Fe3+ was synthesized via a simple and low cost one-step chronoamperometry method on stainless...     

The X2Σ+ state of LiCa studied by Fourier-transform spectroscopy

The paper reports on a successful observation of high resolution Fourier transform spectra of LiCa. The fine structure of the ground state was observed and attributed to effective spin-rotation interaction. The experimental observations are described by two models using potential energy curves. One of them takes into account the fine structure splitting by means of effective constants, the other by means of a R dependent function γ(R), built in the radial Schr?dinger equation. Ab initio calculations were performed for γ(R) which comes close to the experimental function.