CO conversion via hydrogenation over iron-based catalysts on non-carbon supports produces mainly CO or methane by the Sabatier reaction, while the formation of C hydrocarbons is of greatest interest. CH production from CO may be considered as a two-step process with the initial formation of carbon monoxide by the reverse water gas shift reaction followed by the Fischer-Tropsch synthesis (FTS). In the present work CO hydrogenation over iron-based catalysts (Fe, FeCr, FeK) deposited on a carbon carrier has been studied.
View Article and Find Full Text PDFBackground: Whether spinocerebellar ataxia 27B (SCA27B) may present as a cerebellar multiple system atrophy (MSA-C) mimic remains undetermined.
Objectives: To assess the prevalence of FGF14 (GAA) expansions in patients with MSA-C, to compare SCA27B and MSA-C clinical presentation and natural history.
Methods: FGF14 expansion screening combined with longitudinal deep-phenotyping in a prospective cohort of 195 patients with sporadic late-onset cerebellar ataxia.
Introduction: Longitudinal studies of child mental disorders in the general population (herein study) investigate trends in prevalence, incidence, risk/protective factors, and sequelae for disorders. They are time and resource intensive but offer life-course perspectives and examination of causal mechanisms. Comprehensive syntheses of the methods of existing studies will provide an understanding of studies conducted to date, inventory studies, and inform the planning of new longitudinal studies.
View Article and Find Full Text PDFBackground: Heterozygous GAA expansions in the FGF14 gene have been related to autosomal dominant cerebellar ataxia (SCA27B-MIM:620174). Whether they represent a common cause of sporadic late-onset cerebellar ataxia (SLOCA) remains to be established.
Objectives: To estimate the prevalence, characterize the phenotypic spectrum, identify discriminative features, and model longitudinal progression of SCA27B in a prospective cohort of SLOCA patients.
The fundamental role of the carbon carrier Sibunit® in the formation of active and selective phases in low-percentage Pt-containing catalysts Pt/C, Pt/Ni/C, Pt/Ni-Cr/C for the complete dehydrogenation of bicyclohexyl into biphenyl (320 °C, 1 atm) is shown. The Pt/Ni-Cr/C catalyst showed the greatest activity and selectivity in the complete dehydrogenation of bicyclohexyl into biphenyl. Detailed analysis of the catalyst surface by XPS, TEM-HR and EDX methods revealed two main processes associated with the high activity and successful course of the reaction of bicyclohexyl dehydrogenation: the formation of an active carbide PtC phase and graphitization of the carbon carrier.
View Article and Find Full Text PDFBackground: Despite recent progress in the field of genetics, sporadic late-onset (> 40 years) cerebellar ataxia (SLOCA) etiology remains frequently elusive, while the optimal diagnostic workup still needs to be determined. We aimed to comprehensively describe the causes of SLOCA and to discuss the relevance of the investigations.
Methods: We included 205 consecutive patients with SLOCA seen in our referral center.
Hydrogenation of phenol in aqueous solutions on Pt-Ni/SiO, Pt-Ni-Cr/AlO, Pt/C, and Ru/C catalysts was studied at temperatures of 150-250 °C and pressures of 40-80 bar. The possibility of hydrogenation of hydrolysis lignin in an aqueous medium in the presence of a Ru/C catalyst is shown. The conversion of hydrolysis lignin and water-soluble sodium lignosulfonate occurs with the formation of a complex mixture of monomeric products: a number of phenols, products of their catalytic hydrogenation (cyclohexanol and cyclohexanone), and hydrogenolysis products (cyclic and aliphatic C-C hydrocarbons).
View Article and Find Full Text PDFObjectives: Nigrostriatal dopaminergic denervation (NSDD) remains poorly characterized in cerebellar multiple system atrophy (MSA-C). We aimed to study NSDD progression in MSA-C and evaluate the capacity for [123I]-FP-CIT-SPECT and parkinsonism to differentiate MSA-C from idiopathic late-onset cerebellar ataxia (ILOCA).
Methods: We included 85 patients successively referred for sporadic late-onset cerebellar ataxia (SLOCA).
Background: The recent lockdown due to the COVID-19 pandemic has been linked to a higher incidence of psychiatric manifestations and substance abuse. The recreative use of nitrous oxide is more and more widespread and neurological complications are frequent.
Methods: We report clinical characteristics and biological findings of five consecutive patients presenting to our tertiary care center between April 2020 and February 2021 with various neurological symptoms occurring after recent nitrous oxide abuse.
Reduction of CO with hydrogen into CO was studied for the first time on alumina-supported Co and Fe catalysts under supercritical conditions with the goal to produce either CO or CH as the target products. The extremely high selectivity towards methanation close to 100% was found for the Co/AlO catalyst, whereas the Fe/AlO system demonstrates a predominance of hydrogenation to CO with noticeable formation of ethane (up to 15%). The space-time yield can be increased by an order of magnitude by using the supercritical conditions as compared to the gas-phase reactions.
View Article and Find Full Text PDFPurpose: The aim of the study was to evaluate the prevalence of acute kidney injury (AKI) in a cohort of surgically treated patients with peripheral artery disease (PAD) and its association with the short-term and long-term outcome.
Materials And Methods: We conducted a retrospective cohort study on all the consecutive PAD inpatients in 2008. Data on the patients' demographic characteristics, medical history, treatment, outcome and laboratory tests measurements were retrieved from the medical records.
The discovery of 5 subtypes of dopamine receptors revealed their important role in development of arterial hypertension and obesity. Reduce of their functional activity or number with age conduces to the increase of tone of the sympathetic nervous system, dyspoiesis of leptin, hyperphagia, development of obesity and arterial hypertension. Prescription of dopamine agonists conduces to reduction of in, normalization of leptin, diminishing of appetite and body mass, decrease of blood pressure.
View Article and Find Full Text PDFThis paper presents an analysis of the thermodynamics of a model glass former. We have performed equilibrium sampling of a popular binary Lennard-Jones model, employing parallel tempering Monte Carlo to cover the crystalline, amorphous, and liquid regions of configuration space. Disconnectivity graphs are used to visualize the potential energy landscape in the vicinity of a crystalline geometry and in an amorphous region of configuration space.
View Article and Find Full Text PDFFamiliar concepts for small molecules may require reinterpretation for larger systems. For example, rearrangements between geometrical isomers are usually considered in terms of transitions between the corresponding local minima on the underlying potential energy surface, V. However, transitions between bulk phases such as solid and liquid, or between the denatured and native states of a protein, are normally addressed in terms of free energy minima.
View Article and Find Full Text PDFWe present a "basin-sampling" approach for calculation of the potential energy density of states for classical statistical models. It combines a Wang-Landau-type uniform sampling of local minima and a novel approach for approximating the relative contributions from local minima in terms of the volumes of basins of attraction. We have employed basin-sampling to study phase changes in atomic clusters modeled by the Lennard-Jones potential and for ionic clusters.
View Article and Find Full Text PDFPhilos Trans A Math Phys Eng Sci
February 2006
Acoustic waves are generated by the convective motions in the solar convection zone. When propagating upwards into the chromosphere they reach the height where the sound speed equals the Alfvén speed and they undergo mode conversion, refraction and reflection. We use numerical simulations to study these processes in realistic configurations where the wavelength of the waves is similar to the length scales of the magnetic field.
View Article and Find Full Text PDFOscillatory phenomena observed in sunspot umbrae and penumbrae are reviewed and critically discussed. A natural interplay between the thermal atmospheric stratification and the ordered collimation imposed by the intense magnetic field leads naturally to the characteristic properties of the umbral chromospheric and photospheric oscillations and their interpretation as low-beta (beta = 8pip/B2) slow magneto-acoustic-gravity waves guided along the ambient magnetic field.
View Article and Find Full Text PDFCatastrophe theory predicts that in certain limits universal relations should exist between barrier heights, curvatures and the positions of local maxima and minima on a potential or free energy surface. In the present work we investigate these relations for both first- and second-order phase transitions, revealing that the ideal ratios often hold quite well over a wide range of conditions. This elementary catastrophe theory is illustrated for the melting transition of an atomic cluster, the isotropic-to-nematic transition in a liquid crystal, and the ferromagnetic-to-paramagnetic phase transition in the two-dimensional Ising model.
View Article and Find Full Text PDFAltogether eight keto and enol tautomers of guanine were studied theoretically in the gas phase, in a microhydrated environment (1 and 2 water molecules) and in bulk water. The structures of isolated, as well as mono- and dihydrated tautomers were determined by means of the RI-MP2 method using the extended TZVPP (5s3p2d1f/3s2p1d) basis set. The relative energies of isolated tautomers included the correction to higher correlation energy terms evaluated at the CCSD(T)/aug-cc-pVDZ level.
View Article and Find Full Text PDFPhys Rev E Stat Nonlin Soft Matter Phys
November 2002
We investigate the continuum limit of a class of self-organized critical lattice models for solar flares. Such models differ from the classical numerical sandpile model in their formulation of stability criteria in terms of the curvature of the nodal field, and are known to belong to a different universality class. A fourth-order nonlinear hyperdiffusion equation is reverse engineered from the discrete model's redistribution rule.
View Article and Find Full Text PDFPhys Rev E Stat Nonlin Soft Matter Phys
April 2002
We investigate the geometrical properties of avalanches in self-organized critical models of solar flares. Traditionally, such models differ from the classical sandpile model in their formulation of stability criteria in terms of the curvature of the nodal field, and belong to a distinct universality class. With a view toward comparing these properties to those inferred from spatially and temporally resolved flare observations, we consider the properties of avalanche peak snapshots, time-integrated avalanches in two and three dimensions, and the two-dimensional projections of the latter.
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