Search results for " Structural"

Structure of Aspergillus niger epoxide hydrolase at 1.8 A resolution: implications for the structure and function of the mammalian microsomal class o…

2000

AbstractBackground: Epoxide hydrolases have important roles in the defense of cells against potentially harmful epoxides. Conversion of epoxides into less toxic and more easily excreted diols is a universally successful strategy. A number of microorganisms employ the same chemistry to process epoxides for use as carbon sources.Results: The X-ray structure of the epoxide hydrolase from Aspergillus niger was determined at 3.5 Å resolution using the multiwavelength anomalous dispersion (MAD) method, and then refined at 1.8 Å resolution. There is a dimer consisting of two 44 kDa subunits in the asymmetric unit. Each subunit consists of an α/β hydrolase fold, and a primarily helical lid over the…

The Monod-Wyman-Changeux allosteric model accounts for the quaternary transition dynamics in wild type and a recombinant mutant human hemoglobin

2012

International audience; The acknowledged success of the Monod-Wyman-Changeux (MWC) allosteric model stems from its efficacy in accounting for the functional behavior of many complex proteins starting with hemoglobin (the paradigmatic case) and extending to channels and receptors. The kinetic aspects of the allosteric model, however, have been often neglected, with the exception of hemoglobin and a few other proteins where conformational relaxations can be triggered by a short and intense laser pulse, and monitored by time-resolved optical spectroscopy. Only recently the application of time-resolved wide-angle X-ray scattering (TR-WAXS), a direct structurally sensitive technique, unveiled th…

Novel 3D bio-macromolecular bilinear descriptors for protein science: Predicting protein structural classes

2015

In the present study, we introduce novel 3D protein descriptors based on the bilinear algebraic form in the ℝn space on the coulombic matrix. For the calculation of these descriptors, macromolecular vectors belonging to ℝn space, whose components represent certain amino acid side-chain properties, were used as weighting schemes. Generalization approaches for the calculation of inter-amino acidic residue spatial distances based on Minkowski metrics are proposed. The simple- and double-stochastic schemes were defined as approaches to normalize the coulombic matrix. The local-fragment indices for both amino acid-types and amino acid-groups are presented in order to permit characterizing fragme…

When two become one: Integrating FRET and EPR into one structural model

2021

Ultimate Shear of RC Beams with Corroded Stirrups and Strengthened with FRP

2019

Transverse reinforcement plays a key role in the response behavior of reinforced concrete beams. Therefore, corrosion of steel stirrups may change the failure mode of elements from bending to shear, leading to a brittle and catastrophic crisis. It is important to strengthen reinforced concrete beams with corroded stirrups to enhance the shear resistance. This paper presents a formulation, based on the modified compression field theory, to estimate the ultimate shear of reinforced concrete beams strengthened with FRP, because of stirrup corrosion. The detrimental effect of corrosion on steel stirrup yield strength was taken into account by introducing an empirical decay law. The effective st…

Nonlinear Analysis of Beams Reinforced in Shear with Stirrups and Steel Fibers

2012

The modified compression field theory (MCFT) and the disturbed stress field model (DSFM) are often used to predict the nonlinear behavior of reinforced concrete structures. This study presents several extensions of the MCFT and DSFM to the case of high-strength steel fiber-reinforced concrete beams subjected to transverse loads. Experimental four-point bending tests were conducted on 12 concrete beams with a different percentage of fibers and/or stirrups. To validate the updates introduced in the analytical models, numerical analysis was performed using nonlinear finite element software. Modeling of the post-peak softening branch of the tensile and compressive constitutive curves of fibrous…

Savoir évaluer les compétences développées par les élèves : quels outils à la disposition du chercheur en éducation ?

2008

08099; Cet article porte sur la structure et l'évolution des compétences développées par les élèves au cours de l'école élémentaire. A partir d'analyses menées sur les données de panel du ministère de l'Education nationale, le questionnement général repose sur une mesure originale des compétences, basée sur des modèles structuraux. Il comporte deux aspects complémentaires. Le premier concerne la transversalité des apprentissages qui s'inscrivent dans une logique d'interdépendance. La maîtrise d'une compétence peut être ainsi fortement liée à la maîtrise d'autres compétences appartenant, soit à un même domaine d'acquisition, soit à des domaines différents ; la notion de bloc de compétences e…

A new algorithm for a robust solution of the fully dynamic Saint-Venant equations

2003

A new procedure for the numerical solution of the fully dynamic shallow water equations is presented. The procedure is a fractional step methodology where the original system is split into two sequential ones. The first system differs from the original one because of the head gradient term, that is treated as constant and equal to the value computed at the end of the previous time step. The solution of this system, called kinematic, is computed in each element using a spatial zero order approximation for both the heads and the flow rates by means of integration of single ODEs. The second system is called diffusive, contains in the momentum equations only the complementary terms and can be e…

Effect of ageing on the morphology and creep and recovery of polymer-modified bitumens

2018

Polymer additives are used to improve the properties of road bitumens including their oxidative resistance. However, their usage as anti-oxidative materials remains relatively unclear. This study aims to investigate the changes in the morphology and the rheological response of polymer modified bitumens used in road pavement construction caused by ageing. An elastomer (radial styrene butadiene styrene, SBS) and a plastomer (ethyl vinyl acetate, EVA) polymer were mixed with one base bitumen at three polymer concentrations. The bitumens were RTFO and PAV aged. The morphology of the bitumens was captured by fluorescence microscopy while the rheological properties were measured by means of the m…

Students' school performance, task-focus, and situation-specific motivation

2015

Going beyond studies of individual differences in and profiles of students' motivation, we investigated situation-specific (intra-personal) experiences of autonomous (enjoyment, interest, and task choice) and controlled (having to do, and the teacher wanting them to do a task) motivation across learning situations during one week, and how these were related to student characteristics (teacher rated academic performance and task-focus). Three-hundred and fourteen primary school students (Years 5 and 6) completed electronic questionnaires on Personal Digital Assistants, on an average of 11.2 learning episodes during a week. Multilevel Structural Equation Models provided support for a model ba…