Polytechnic University of Turin

About: Polytechnic University of Turin is a education organization based out in Turin, Piemonte, Italy. It is known for research contribution in the topics: Finite element method & Computer science. The organization has 11553 authors who have published 41395 publications receiving 789320 citations. The organization is also known as: POLITO & Politecnico di Torino.

BiVO4 as photocatalyst for solar fuels production through water splitting: A short review

Abstract: As solar energy is the most abundant energy source, it has been widely exploited for thermal and electrical power generation. However, owing to the greater convenience of chemical energy storage, such as H 2 , compared to electricity, solar fuels have been considered as one of the most promising technological concepts due to their potential higher efficiency and environmental suitability. In this context, the photocatalytic water splitting into O 2 and solar fuels ( e.g. H 2 ) is a topic of current interest. Furthermore, the development of photocatalysts that can utilize the whole electromagnetic spectrum is preferable in order to enhance the overall water splitting efficiency. Direct photocatalytic water splitting is a challenging problem because the water oxidation (WO) reaction is thermodynamically uphill. Hence, several WO photocatalysts have been developed and assessed over the last few decades, and it has been reported that BiVO 4 is one of the most active O 2 evolution photocatalysts. In this review, a first introduction regarding the solar fuel production and the water oxidation reaction is reported. Subsequently, the crystal and electronic structures as well as the optical properties that are closely related to the photoelectrochemical properties of BiVO 4 are described. Finally, the monoclinic BiVO 4 synthesis methods and the optimization methods to improve the performances of BiVO 4 are discussed. The information gained from this analysis contributes to the better understanding of the main parameters affecting the activity and will ultimately lead to the optimized synthesis of a more efficient BiVO 4 photocatalytic material.

Structural basis of histidine kinase autophosphorylation deduced by integrating genomics, molecular dynamics, and mutagenesis.

Abstract: Signal transduction proteins such as bacterial sensor histidine kinases, designed to transition between multiple conformations, are often ruled by unstable transient interactions making structural characterization of all functional states difficult. This study explored the inactive and signal-activated conformational states of the two catalytic domains of sensor histidine kinases, HisKA and HATPase. Direct coupling analyses, a global statistical inference approach, was applied to >13,000 such domains from protein databases to identify residue contacts between the two domains. These contacts guided structural assembly of the domains using MAGMA, an advanced molecular dynamics docking method. The active conformation structure generated by MAGMA simultaneously accommodated the sequence derived residue contacts and the ATP-catalytic histidine contact. The validity of this structure was confirmed biologically by mutation of contact positions in the Bacillus subtilis sensor histidine kinase KinA and by restoration of activity in an inactive KinA(HisKA):KinD(HATPase) hybrid protein. These data indicate that signals binding to sensor domains activate sensor histidine kinases by causing localized strain and unwinding at the end of the C-terminal helix of the HisKA domain. This destabilizes the contact positions of the inactive conformation of the two domains, identified by previous crystal structure analyses and by the sequence analysis described here, inducing the formation of the active conformation. This study reveals that structures of unstable transient complexes of interacting proteins and of protein domains are accessible by applying this combination of cross-validating technologies.

Faithful effective-one-body waveforms of small-mass-ratio coalescing black-hole binaries

Abstract: We address the problem of constructing high-accuracy, faithful analytic waveforms describing the gravitational wave signal emitted by inspiralling and coalescing binary black holes. We work within the effective-one-body (EOB) framework and propose a methodology for improving the current (waveform) implementations of this framework based on understanding, element by element, the physics behind each feature of the waveform and on systematically comparing various EOB-based waveforms with exact waveforms obtained by numerical relativity approaches. The present paper focuses on small-mass-ratio nonspinning binary systems, which can be conveniently studied by Regge-Wheeler-Zerilli-type methods. Our results include (i) a resummed, 3 PN-accurate description of the inspiral waveform, (ii) a better description of radiation reaction during the plunge, (iii) a refined analytic expression for the plunge waveform, (iv) an improved treatment of the matching between the plunge and ring-down waveforms. This improved implementation of the EOB approach allows us to construct complete analytic waveforms which exhibit a remarkable agreement with the exact ones in modulus, frequency, and phase. In particular, the analytic and numerical waveforms stay in phase, during the whole process, within $\ifmmode\pm\else\textpm\fi{}1.1%$ of a cycle. We expect that the extension of our methodology to the comparable-mass case will be able to generate comparably accurate analytic waveforms of direct use for the ground-based network of interferometric detectors of gravitational waves.

Free vibration analysis of functionally graded shells by a higher-order shear deformation theory and radial basis functions collocation, accounting for through-the-thickness deformations

Abstract: This paper deals with free vibration problems of functionally graded shells. The analysis is performed by radial basis functions collocation, according to a higher-order shear deformation theory that accounts for through-the-thickness deformation. The equations of motion and the boundary conditions are obtained by Carrera’s Unified Formulation resting upon the principle of virtual work, and further interpolated by collocation with radial basis functions. Numerical results include spherical as well as cylindrical shell panels with all edges clamped or simply supported and demonstrate the accuracy of the present approach.