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Described here is a titanocene‐catalyzed reaction for the synthesis of acetals and hemiaminals from benzylic ethers and benzylic amines, respectively, with pendant epoxides. The reaction proceeds by catalysis in single‐electron steps. The oxidative addition comprises an epoxide opening. An H‐atom transfer, to generate a benzylic radical, serves as a radical translocation step, and an organometallic oxygen rebound as a reductive elimination. The reaction mechanism was studied by high‐level dispersion corrected hybrid functional DFT with implicit solvation. The low‐energy conformational space was searched by the efficient CREST program. The stereoselectivity was deduced from the lowest lying benzylic radical structures and their conformations are controlled by hyperconjugative interactions and steric interactions between the titanocene catalyst and the aryl groups of the substrate. An interesting mechanistic aspect is that the oxidation of the benzylic center occurs under reducing conditions. [ABSTRACT FROM AUTHOR]

Yeast amino acid transporters of the APC superfamily are responsible for the proton motive force‐driven uptake of amino acids into the cell, which for most secondary transporters is a reversible process. The l‐lysine proton symporter Lyp1 of Saccharomyces cerevisiae is special in that the Michaelis constant from out‐to‐in transport (Kmout→in) is much lower than Kmin→out, which allows accumulation of l‐lysine to submolar concentration. It has been proposed that high intracellular lysine is part of the antioxidant mechanism of the cell. The molecular basis for the unique kinetic properties of Lyp1 is unknown. We compared the sequence of Lyp1 with APC para‐ and orthologues and find structural features that set Lyp1 apart, including differences in extracellular loop regions. We screened the extracellular loops by alanine mutagenesis and determined Lyp1 localization and activity and find positions that affect either the localization or activity of Lyp1. Half of the affected mutants are located in the extension of extracellular loop 3 or in a predicted α‐helix in extracellular loop 4. Our data indicate that extracellular loops not only connect the transmembrane helices but also serve functionally important roles. [ABSTRACT FROM AUTHOR]

Herein, the conversion times of biomass pyrolysis are measured at temperatures between 450 and 550 °C and particle size fractions between 0 and 400 μm using a cyclonic thermogravimetric analyzer (TGA) device. Beech, spruce, and ash wood are investigated, as well as torrefied samples. The conversion time decreases with the increasing temperature from 7 to less than 1 s. The influence of the type of biomass on the conversion time is limited and only significant for low temperatures, when kinetics dominates the conversion process. A clear influence of the torrefaction process on the pyrolysis conversion time is noted and can be explained by the modified porosity of the biomass particles during the torrefaction process. Kinetic data are extracted from the conversion times, and a model is developed for a better interpretation of the measured results. The model shows good comparison with the experimental data and may also be used for design purposes of fast pyrolysis reactors. [ABSTRACT FROM AUTHOR]

The Netherlands is characterized by highly variable land use within a small area, and a strong influence of the North Sea on national climate. Devoid of significant topography, it is an excellent location for assessing the relative influence of various factors on fog occurrence in the absence of terrain effects. Using observations from a dense network of weather stations throughout the country, the climatology of fog in the Netherlands is assessed over a period of 45 years. On a national scale, interannual variability is linked to changes in synoptic pressure‐gradient forcing. Within the country, a comprehensive in‐depth analysis of regional differences between fog occurrence is made, together with an assessment of local physical factors which could bias fog formation in one location over another. Regional variability is shown to be strongly related to the mesoscale influences of urbanization and the North Sea. In fact, some locations experience over twice as much fog as others. From this finding, a simple index is presented, which combines the water and urban fraction surrounding a station. This "Regionally Weighted Index" (RWI) is able to accurately sort the stations according to their relative fogginess. Its practical use is encouraged for assessing a given site's climatological favourability, even when in situ meteorological observations are unavailable. [ABSTRACT FROM AUTHOR]

Abstract: We present a combined electrochemical, kinetic, and synthetic study with a novel and easily accessible class of titanocene catalysts for catalysis in single‐electron steps. The tailoring of the electronic properties of our Cp2TiX‐catalysts that are prepared in situ from readily available Cp2TiX2 is achieved by varying the anionic ligand X. Of the complexes investigated, Cp2TiOMs proved to be either equal or substantially superior to the best catalysts developed earlier. The kinetic and thermodynamic properties pertinent to catalysis have been determined. They allow a mechanistic understanding of the subtle interplay of properties required for an efficient oxidative addition and reduction. Therefore, our study highlights that efficient catalysts do not require the elaborate covalent modification of the cyclopentadienyl ligands. [ABSTRACT FROM AUTHOR]

Abstract: Background: More than 20 years ago, our reappraisal of the Hutchinson's sign (HS) gave birth to the concept of the pseudo‐Hutchinson's sign. Objectives: We have found it interesting to emphasize some important histologic points and to expand the list of the numerous HS simulants. Methods: We have examined the cutaneous samples taken from the pigmented skin of patients in association with nail matrix biopsy. We have also extended the long list of non‐melanoma HS based on comprehensive literature review. Results: Histologically, HS may present only as an epidermal pigmentation, depending on the area sampled. Occasionally, there may be a sparse junctional melanocytic proliferation which does not demonstrate cytologic atypia due to an underlying melanocytic naevus of the nail matrix. However, early HS often shows a melanoma in situ, with a HS at the proximal nail fold (PNF) and confluent “atypical” melanocytes in the nail matrix. Finally, involvement of the PNF, nail matrix and nail bed containing atypical melanocytes in irregular array may be seen in more advanced lesions. The recent literature on non‐melanoma HS simulants is summarized and clinical examples are provided. Conclusion: The mere presence of periungual pigmentation is neither clinically nor histologically pathognomonic of subungual melanoma and justifies the usefulness of this work stressing the non‐melanoma HS. [ABSTRACT FROM AUTHOR]

Decisions about disaster preparedness are rarely informed by cost-benefit analyses. This paper presents an economic model to address the thorny question, 'how prepared is prepared enough?' Difficulties related to the use of cost-benefit analysis in the field of disaster management concern the tension between the large number of high-probability events that can be handled by a single emergency response unit and the small number of low-probability events that must be handled by a large number of them. A further special feature of disaster management concerns the opportunity for cooperation between different emergency response units. To account for these issues, we introduce a portfolio approach. Our analysis shows that it would be useful to define disaster preparedness not in terms of capacities, but in terms of the frequency with which response capacity is expected to fall short. [ABSTRACT FROM AUTHOR]

Evidence is accumulating that calcium-rich microdeposits in the vascular wall might play a crucial role in the onset and progression of atherosclerosis. Here we investigated an atherosclerotic lesion of the carotid artery in an established murine model, i.e. the apolipoprotein E-deficient (APOE) mouse to identify (i) the presence of microcalcifications, if any, (ii) the elemental composition of microcalcifications with special reference to calcium/phosphorus mass ratio and (iii) co-localization of increased concentrations of iron and zinc with microcalcifications. Atherosclerosis was induced by a flow-divider placed around the carotid artery resulting in low and high shear-stress regions. Element composition was assessed with a proton microprobe. Microcalcifications, predominantly present in the thickened intima of the low shear-stress region, were surrounded by areas with normal calcium levels, indicating that calcium-precipitation is a local event. The diameter of intimal microcalcifications varied from 6 to 70 μm. Calcium/phosphorus ratios of microcalcifications varied from 0.3 to 4.8, mainly corresponding to the ratio of amorphous calcium-phosphate. Increased iron and zinc concentrations commonly co-localized with microcalcifications. Our findings indicate that the atherosclerotic process in the murine carotid artery is associated with locally accumulated calcium, iron and zinc. The calcium-rich deposits resemble amorphous calcium phosphate rather than pure hydroxyapatite. We propose that the APOE mouse, in which atherosclerosis was evoked by a flow-divider, offers a useful model to investigate the pathophysiological significance of accumulation of elements such as calcium, iron and zinc. [ABSTRACT FROM AUTHOR]