Numerous attempts to determine the degree ofaggregation ofcompounds 1 by using differential-vapor osmometry in anology to the experiments of Bickelhaupt et al. led to the expected association value of 2, but with a low reproducibility of our results and a large standard deviation. For a recent review on the reactions of organozinc derivatives: P.Diazo compounds with suitably oriented substituents can undergo intramolecular cyclizations by metal-promoted reactions that presumably involve insertion of metallocarbenes into C -H Most of the known reactions of this type involve rhodium complexes,[31 typically bearing optically pure ligands from amino but two of us recently reported that optically active copper catalysts seemed to be superior for the reaction shown in Scheme I .Is1 In the best case, the product 3 was isolated in 64 % yield as a 2.3: 1 .O mixture of diastereomers. The object of the current study was to use high throughput catalyst screening to improve these results. CO&-Men) COp(L-Men) major diastereomer Scheme 1. L-Men = L-menthyl r] Prof.

A kinetic model for methanol (MeOH) synthesis over Cu/ZnO/Al2O3/ZrO2 catalyst has been developed and selected to evaluate the effect of carbon dioxide on the reaction rates due to its high activity and stability. Detailed kinetic mechanism, on the basis of different sites on Cu for the adsorption of carbon monoxide and carbon dioxide, is applied, and the water−gas shift (WGS) reaction is included in order to provide the relationship between the hydrogenations of carbon monoxide and carbon dioxide. Parameter estimation results show that, among 48 reaction rates from different combinations of rate determining steps (RDSs) in each reaction, the surface reaction of a methoxy species, the hydrogenation of a formate intermediate HCO2, and the formation of a formate intermediate are the RDS for CO and CO2 hydrogenations and the WGS reaction, respectively. It is shown that the CO2 hydrogenation rate is much lower than the CO hydrogenation rate, and this affects the methanol production rate. However, carbon dioxide decreases the WGS reaction rate, which prevents methanol from converting to dimethyl ether, a byproduct. In such a way, a small fraction of carbon dioxide accelerates the production of methanol indirectly within a limited range, showing a threshold value of the CO2 fraction for the maximum methanol synthesis.

No abstract

Amyloid diseases like Alzheimer's disease and familial amyloidosis of Finnish type (FAF) stem from endoproteolytic cleavage of a precursor protein to generate amyloidogenic peptides that accumulate as amyloid deposits in a tissue-specific manner. FAF patients deposit both 8 and 5 kDa peptides derived from mutant (D187Y/N) plasma gelsolin in the extracellular matrix (ECM). The first of two aberrant sequential proteolytic events is executed by furin to yield a 68 kDa (C68) secreted fragment. We now identify the metalloprotease MT1-matrix metalloprotease (MMP), an integral membrane protein active in the ECM, as a protease that processes C68 to the amyloidogenic peptides. We further demonstrate that ECM components are capable of accelerating gelsolin amyloidogenesis. Proteolysis by MT1-MMP-like proteases proximal to the unique chemical environment of the ECM offers an explanation for the tissue-specific deposition observed in FAF and provides critical insight into new therapeutic strategies.