Stereochemical course of the hydrolysis reaction catalyzed by chitinases Al and D from Bacillus circulans WL-12

AbstractChitinases A1 and D were purified from the periplasmic proteins produced by Escherichia coli HB101 harbouring recombinant plasmids carrying respectively the chiA and chiD genes of Bacillus circulans WL-12. HPLC analysis indicated that during the hydrolysis of chitotriose, both chitinases initially produce N-acetylglucosamine and only one anomer of chitobiose. 1H NMR spectroscopy of the hydrolysis of chitotetraitol showed that this anomer corresponds to β-chitobiose, demonstrating that chitinases Al and D act by a molecular mechanism that retains the anomeric configuration. This mechanism is similar to that of lysozymes although both chitinases belong to a family of proteins sharing no demonstrable amino acid sequence similarity with lysozymes

Antioxidant vitamin intakes assessed using a food-frequency questionnaire: correlation with biochemical status in smokers and non-smokers

The increasing interest in the possible role of antioxidant vitamins in many disease states means that methods of assessing vitamin intakes which are suitable for large-scale investigations are now required. The suitability of the food-frequency questionnaire, which was developed by the Medical Research Council - Cardiff Group, for determining dietary intake of antioxidant vitamins in epidemiological studies was investigated in 196 Scottish men. The validity of the dietary data was assessed by comparison with serum vitamin concentrations, and separate analyses were performed for current smokers and non-smokers. The results showed that total energy intake and the percentage of energy derived from sugar were higher in smokers, and that both dietary and serum values of vitamin C, β-carotene and vitamin E were lower in smokers than non-smokers. After adjustment for serum lipids, energy intake and body mass index, correlation coefficients between dietary and serum vitamins C and E were similar for smokers (r 0.555 and 0.25 respectively) and non-smokers (r 0.58 and 0.32 respectively). Correlation between dietary and serum carotenes was reduced from 0.28 in non-smokers to 0.09 in smokers and correlations for retinol and total vitamin A were weakly significant only for non-smokers. The food-frequency questionnaire assigned > 70% of subjects correctly into the upper or lower plus adjacent tertiles of serum vitamin values, with the exception of β-carotene and total vitamin A for smokers. Thus, the food-frequency questionnaire appeared to be an adequate tool for assigning individuals into tertiles of serum antioxidant vitamins with the main exception of β-carotene for smokers. Marked differences do occur between the vitamins and between the smoking groups which may reflect reduced accuracy of reporting on the food-frequency questionnaire or differential absorption and metabolism of the vitamin

MAGMA : inference and prediction using multi-task Gaussian processes with common mean

A novel multi-task Gaussian process (GP) framework is proposed, by using a common mean process for sharing information across tasks. In particular, we investigate the problem of time series forecasting, with the objective to improve multiple-step-ahead predictions. The common mean process is defined as a GP for which the hyper-posterior distribution is tractable. Therefore an EM algorithm is derived for handling both hyper-parameters optimisation and hyper-posterior computation. Unlike previous approaches in the literature, the model fully accounts for uncertainty and can handle irregular grids of observations while maintaining explicit formulations, by modelling the mean process in a unified GP framework. Predictive analytical equations are provided, integrating information shared across tasks through a relevant prior mean. This approach greatly improves the predictive performances, even far from observations, and may reduce significantly the computational complexity compared to traditional multi-task GP models. Our overall algorithm is called MAGMA (standing for Multi tAsk GPs with common MeAn). The quality of the mean process estimation, predictive performances, and comparisons to alternatives are assessed in various simulated scenarios and on real datasets

β-Decay Half-Lives of 76;77Co, 79;80Ni, and 81Cu: Experimental Indication of a Doubly Magic 78Ni

published_or_final_versio

New isomers in 125 Pd 79 and 127 Pd 81 : Competing proton and neutron excitations in neutron-rich palladium nuclides towards the N=82 shell closure

The neutron-rich isotopes of palladium have attracted considerable interest in terms of the evolution of the neutron shell closure and its influence on the r-process nucleosynthesis. In this Letter, we present the first spectroscopic information on the excited states in 125Pd79 and 127Pd81 studied using the EURICA γ-ray spectrometer, following production via in-flight fission of a high-intensity 238U beam at the RIBF facility. New isomeric states with half-lives of 144(4) ns and 39(6) μs have been assigned spins and parities of () and () in 125Pd and 127Pd, respectively. The observed level properties are compared to a shell-model calculation, suggesting the competition between proton excitations and neutron excitations in the proton-hole and neutron-hole systems in the vicinity of the doubly magic nucleus 132Sn.Part of the WAS3ABi was supported by the Rare Isotope Science Project which is funded by MSIP and NRF of Korea. This work was supported by the Priority Centers Research Program in Korea (2009-0093817), OTKA contract number K100835, the U.S. DOE, Office of Nuclear Physics (Contract No. DE-AC02-06CH11357), NRF-2016R1A5A1013277 and NRF-2013M7A1A1075764, the Spanish Ministerio de Economía y Competitividad under contract FPA2017-84756-C4-2-P, the European Commission through the Marie Curie Actions call FP7-PEOPLE-2011-IEF (Contract No. 300096), German BMBF under Contract No: 05P12PKFNE, JSPS KAKENHI Grant No. 24740188 and 25247045, the National Natural Science Foundation of China (Nos. 11505302, 11575112), the National Key Program for S&T Research and Development (No. 2016YFA0400501), and STFC (UK)

Modélisation et simulation numérique par méthode FFT de la localisation des contraintes internes et des densités de dislocations dans un acier composite nouvelle génération 'Fe-TiB2'

International audienceUn modèle d'élasto-viscoplasticité cristalline (EVP), basé sur la méthode des transformées de Fourier rapide (FFT) et couplé à la mécanique des champs de dislocations (MFDM), est présenté et appliqué afin de décrire l'évolution en déformation des densités de Dislocations Géométriques Nécessaires (GND) dans un composite à matrice métallique Fe-TiB2. Des volumes élémentaires réalistes basés sur la microstructure réelle sont considérés. Les résultats montrent la capacité de l'approche à prédire les gradients des champs mécaniques proches des interfaces matrice/renforts