Numerical simulation of aileron buzz using an adaptive-grid compressible flow solver for dynamic meshes

The paper presents numerical results from a novel scheme for the solution of the flow equations in two dimensional domains by an Arbitrary Lagrangian Eulerian formulation able to cope with deforming and adaptive two dimensional grids without recurring to any explicit interpolation scheme. The method is applied to the investigation of a classical transonic aeroelastic instability phenomenon: the aileron buzz. By resorting to deforming and adaptive grids, the method allows to highlight the dependency of the aeroelastic stability boundaries on the mesh spacing

Finite element modeling of non-equilibrium fluid-wall interaction beyond the continuum regime

The numerical modeling of the aerodynamic interactions at high-altitudes and high-Mach numbers is considered in view of its importance when studying problems where the continuum hypothesis at the foundation of the Navier-Stokes equations becomes invalid. One of the difficulties associated with these flight conditions is that both the velocity and the temperature of the fluid do not abide by the no - slip conditions at the wall. A weak-Galerkin Finite Element formulation of the Maxwell-Smoluchowsky model is introduced to discretize the velocity slip and temperature jump conditions with better accuracy than the standard Finite Element approximation. The methodology is assessed on configurations such as cylinders and spheres for flow conditions ranging from quasi-equilibrium to non-equilibrium. Improvements are observed in the slip regime compared to available data. Nonetheless, the results in the transition regime highlight the need for more sophisticated physical modeling to address non-equilibrium at the wall

Finite element modeling of nonequilibrium fluid-wall interaction at high-Mach regime

The numerical modeling of the aerodynamic interactions at high-Altitudes and high-Mach numbers is considered in view of its importance when studying problems where the continuum hypothesis at the foundation of the Navier- Stokes equations becomes invalid. One of the difficulties associated with these flight conditions is that both the velocity and the temperature of the fluid do not abide by the no-slip conditions at the wall. A weak Galerkin finite element formulation of the Maxwell-Smoluchowki model is introduced to discretize the velocity slip and temperature jump conditions with better accuracy than the standard finite element approximation. The methodology is assessed on configurations such as cylinders and spheres for flow conditions ranging from quasi-equilibrium to nonequilibrium. Improvements are observed in the slip regime compared with available data. Nonetheless, the results in the transition regime highlight the need for more sophisticated physical modeling to address nonequilibrium at the wall

The extraordinary catalytic ability of peroxiredoxins: a combined experimental and QM/MM study on the fast thiol oxidation step

Peroxiredoxins (Prxs) catalyze the reduction of peroxides, a process of key relevance in a variety of cellular processes. The first step in the catalytic cycle of all Prxs is the oxidation of a cysteine residue to sulfenic acid, which occurs 103–107 times faster than in free cysteine. We present an experimental kinetics and hybrid QM/MM investigation to explore the reaction of Prxs with H2O2 using alkyl hydroperoxide reductase E from Mycobacterium tuberculosis as a Prx model. We report for the first time the thermodynamic activation parameters of H2O2 reduction using Prx, which show that protein significantly lowers the activation enthalpy, with an unfavourable entropic effect, compared to the uncatalyzed reaction. The QM/MM simulations show that the remarkable catalytic effects responsible for the fast H2O2 reduction in Prxs are mainly due to an active-site arrangement, which establishes a complex hydrogen bond network activating both reactive species.Fil: Zeida Camacho, Ari Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; ArgentinaFil: Reyes, Aníbal M.. Universidad de la República; UruguayFil: González Lebrero, Mariano Camilo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Biológica; ArgentinaFil: Radi Isola, Rafael. Universidad de la República; UruguayFil: Trujillo, Madia. Universidad de la República; UruguayFil: Estrin, Dario Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Finite-element formulation of a Jacobian-free solver for supersonic viscous flows on hybrid grids

A parallel Jacobian-free solver for supersonic flows on unstructured hybrid meshes is proposed. An edge-based Finite Element formulation is used for spatial discretization with flow stabilized via either AUSM+-up or a Roe scheme. The Jacobian-free Newton-Krylov method is used as linear system solver and the lower-upper symmetric Gauss-Seidel method is used for matrix-free preconditioning. In the present formulation, second order approximations of spatial derivatives of the inviscid fluxes are introduced efficiently. Numerical results for Mach 1.93 flow past a sphere, Mach 4 flow past a waverider, and Mach 10.01 flow past a sphere, are presented

How future surgery will benefit from SARS-COV-2-related measures: a SPIGC survey conveying the perspective of Italian surgeons

COVID-19 negatively affected surgical activity, but the potential benefits resulting from adopted measures remain unclear. The aim of this study was to evaluate the change in surgical activity and potential benefit from COVID-19 measures in perspective of Italian surgeons on behalf of SPIGC. A nationwide online survey on surgical practice before, during, and after COVID-19 pandemic was conducted in March-April 2022 (NCT:05323851). Effects of COVID-19 hospital-related measures on surgical patients' management and personal professional development across surgical specialties were explored. Data on demographics, pre-operative/peri-operative/post-operative management, and professional development were collected. Outcomes were matched with the corresponding volume. Four hundred and seventy-three respondents were included in final analysis across 14 surgical specialties. Since SARS-CoV-2 pandemic, application of telematic consultations (4.1% vs. 21.6%; p < 0.0001) and diagnostic evaluations (16.4% vs. 42.2%; p < 0.0001) increased. Elective surgical activities significantly reduced and surgeons opted more frequently for conservative management with a possible indication for elective (26.3% vs. 35.7%; p < 0.0001) or urgent (20.4% vs. 38.5%; p < 0.0001) surgery. All new COVID-related measures are perceived to be maintained in the future. Surgeons' personal education online increased from 12.6% (pre-COVID) to 86.6% (post-COVID; p < 0.0001). Online educational activities are considered a beneficial effect from COVID pandemic (56.4%). COVID-19 had a great impact on surgical specialties, with significant reduction of operation volume. However, some forced changes turned out to be benefits. Isolation measures pushed the use of telemedicine and telemetric devices for outpatient practice and favored communication for educational purposes and surgeon-patient/family communication. From the Italian surgeons' perspective, COVID-related measures will continue to influence future surgical clinical practice

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Finite-volume solution of two-dimensional compressible flows over dynamic adaptive grids

A novel Finite Volume (FV) technique for solving the compressible unsteady Euler equations is presented for two-dimensional adaptive grids over time dependent geometries. The interpretation of the grid modifications as continuous deformations of the underlying discrete finite volumes allows to determine the solution over the new grid by direct integration of the governing equations within the Arbitrary Lagrangian–Eulerian (ALE) framework, without any explicit interpolation step. The grid adaptation is performed using a suitable mix of grid deformation, edge-swapping, node insertion and node removal techniques in order to comply with the displacement of the boundaries of the computational domain and to preserve the quality of the grid elements. Both steady and unsteady simulations over adaptive grids are presented that demonstrate the validity of the proposed approach. The adaptive ALE scheme is used to perform high-resolution computations of the steady flow past a translating airfoil and of the unsteady flow of a pitching airfoil in both the airfoil and the laboratory reference, with airfoil displacement as large as 200 airfoil chords. Grid adaptation is found to be of paramount importance to preserve the grid quality in the considered problems