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The effects of incoherence on the three-wave coupling process of backward stimulated Raman scattering (SRS) in inhomogeneous plasmas are investigated theoretically and numerically via a three-wave coupling model. The impact of the plasma wave nonlinearity is taken into account, namely, the effect of trapped electrons via a nonlinear frequency shift of the electron plasma wave. Incoherence in the coupling is introduced in the seed wave, and the laser pump wave via bandwidth associated with a Lorentzian power spectrum. It is found that temporal incoherence can suppress the instability as long as the gain associated with spatial amplification in an inhomogeneous plasma (“Rosenbluth gain”) is smaller than 2. Otherwise, kinetic effects may destabilize SRS and significantly increase the backscatter level. For the bandwidth effects of the pump laser, a statistical analysis has been performed to examine the real impact of bandwidth. Moreover, a semi-analytical expression of the growth rate in the nonlinear stage is given. By estimating the bandwidth effects, it is found that a broad bandwidth of the pump laser starts to mitigate the scattering provided that the laser beam coherence time τc is shorter than [Formula: see text], the inverse of the standard SRS growth rate γ0. However, to obtain effective mitigation, by maintaining SRS in an almost linear stage, it is found that the criterion [Formula: see text] has to be fulfilled.

The synergistic catalytic effect of surfactants is highlighted in the photodegradation of Orange G and Eosin Y by TiO2 at alkaline pH.

Trabajo presentado en la 13th International Conference One-Carbon Metabolsim, B-vitamins and Homocysteine, celebrada en Poznán (Polonia) del 12 al 16 de septiembre de 2021., Methionine adenosyltransferases (MATs) are the only enzymes responsible for the biosynthesis of S-adenosylmethionine (AdoMet) from methionine and ATP using Mg2+ and K+ cofactors. Prevalent cytoplasmic isoforms in adult liver hepatocytes are MAT I homotetramers and MAT III homodimers of the catalytic MAT1 subunit with different kinetic properties. In oxidative liver pathology, decreased MAT1A expression renders reduced MAT activity, increased cytoplasmic MAT III content and nuclear accumulation of MAT I and MAT1. Therefore, our aim was to get insights into the regulation of the association/dissociation mechanisms of MAT1 isoforms. Methods used include: site-directed mutagenesis to disrupt dimer-dimer interface polar interactions identified in rat MAT I structure; expression and purification of mutant and control proteins from soluble fractions and inclusion bodies; evaluation of thermal stability by activity measurements; analysis of secondary and quaternary structure changes by far-UV circular dichroism, analytical gel filtration (AGFC) and phenyl Sepharose (PSC) chromatographies; and determination of AdoMet synthesis and tripolyphosphatase kinetics. The results showed decreased expression of most single mutants in the soluble fraction vs wild type MAT¿1 (control), while double mutants appeared mainly in inclusion bodies. Circular dichroism spectra showed low impact of mutations on secondary structure. However, protein thermal stability of N106A and E112L increased, but decreased in Q81T, R85L, R85E and T63V mutants. Notably, dimers were the preferred oligomerization state, but Q81T and R85L exhibited disparities in AGFC and PSC, whereas the dimer contents of R85E, T63V and R85L-E112L increased vs control. Regarding kinetics, those of AdoMet synthesis varied from: i) modest increases in Vmax and affinities for ATP and cations (Q81T); ii) 2-10-fold decreases in Vmax (R85L, R85E, N106A, E112L, T63V, R85L-E112L); iii) reduced methionine, ATP and cations affinities (R85L, R85E, T63V); iv) increased affinity for both substrates, but decreased for Mg2+ (N106A, E112L); and v) diminished ATP and Mg2+ affinities (R85L-E112L). Conversely, tripolyphosphatase kinetics also changed with: i) 2-3 fold increased (R85L, E112L) or decreased Vmax (R85L-E112L); ii) loss of AdoMet stimulation (Q81T, R85L, R85E, N106A, T63V); and iii) increased PPPi affinities in the absence (N106A, E112L, T63V, R85L-E112L) or presence of AdoMet (most mutants, but E112L). Compared to soluble proteins, mutants refolded from inclusion bodies exhibited similar AdoMet synthesis kinetics, but evident differences in tripolyphosphatase kinetics: i) lack of AdoMet stimulation, also exhibited by the control protein; ii) no changes in PPPi affinities; but iii) decreased PPPi affinities for most mutants in the presence of AdoMet. In conclusion, kinetic changes long-described for MAT I and MAT III are mimicked by mutations favoring dimer formation, especially those on R85 and T63 residues., Funding: BMC-2002-00243, BFU 2005-00050, BFU 2008-00666, BFU 2009-0897

International audience; A new fluid model describing backward stimulated Raman scattering (SRS) is presented based on parametric three-wave coupling in multidimensional geometry. It takes into account kinetic effects in the description of the plasma wave via a non linear frequency shift due to trapped electrons. The model is valid in the regime of hot and weakly inhomogeneous plasmas under conditions relevant for inertial confinement fusion with the plasma parameter k L λ De 0.25 (k L standing for the plasma wave number and λ De for the Debye length). Benchmarks of the model have been performed against the Maxwell-particle-in-cell (PIC) code Emi2D in order to calibrate the adjustable parameters controlling the non linear frequency shift. Two major configurations have been tested, one in a homogeneous plasma, with the onset of laser pump depletion and the other in an inhomogeneous plasma, producing auto-resonant growth. Good agreement between fluid and PIC simulations has been found for both configurations, in particular for the growth of SRS, and further on in time for the average backscatter level. The model is a promising tool to be implemented in multi-dimensional laser-plasma interaction packages coupled to hydrodynamics codes in order to compute SRS in mm-size volumes, usually inaccessible with PIC codes.

Capacitive deionization (CDI) has become an important research topic in terms of water purification as it is a cost- and energy efficient approach for the desalination of brackish water. Carbon- based materials are often used as electrodes in this process due to a variety of morphologies and their suitable performance in this field. In recent studies it has been already shown that a conscientiously chosen set of electrode properties has an enormous effect on the performance behavior of CDI cells. However, most of the studies focus on the optimization of the electrosorption capacity, while the question on how material properties influence the kinetic behavior of a CDI setup has been less intensively studied so far. Here we show that the kinetic effects of electrode materials can be studied in great detail by using electrochemical impedance spectroscopy (EIS). EIS studies of CDI electrodes have been reported before, however, in contrast to these we introduce a method of presenting and analyzing EIS results. This is especially suitable for extracting the frequency ranges in which different rate limiting mechanisms dominate. The new Nyquist Incline Frequency plot (NIF) shows the local slope of the Nyquist plot in dependency of the applied frequency. By this, electron transfer and mass transfer mechanisms which show a characteristic slope in the classical Nyquist plot can be directly visualized together with the information in which time domain they occur. The data derived from the new EIS plot show a clear correlation to pore size distributions from BET measurements, as well as effective capacities and electrosorption kinetics, extracted from CDI experiments. Therefore, we think that by using the NIF plot electrode materials for CDI processes can be conveniently characterized and compared within a single diagram, helping to standardize CDI material development.

The kinetic effects of both thermal ions and energetic particles (EPs) on global Alfvén mode generation and structure symmetry breaking are important for the understanding of resonant excitation and EP transport in tokamak plasmas. In this work, the formulation for the study of the beta induced Alfvén eigenmode (BAE) driven by EPs is derived for weakly coupled poloidal harmonics with finite Larmor radius (FLR) and finite orbit width (FOW). Agreement between the theoretical model and corresponding XHMGC simulations is demonstrated. It is shown that including FLR and FOW can lead to the global mode structure broadening. The non-perturbative effects of the energetic particles on global mode structure symmetry breaking is demonstrated. In particular, when the energetic particle drive shifts away from the mode rational surface, volume averaged parallel and radial wave numbers are generated in the plasma as a demonstration of EPs' role on mode structure symmetry breaking. The connection of the mode structure symmetry breaking with experimental observations using ECEI and with particle/momentum transport are discussed. © EURATOM 2018.

We consider the transport of vapour caused by the evaporation of a thin, axisymmetric, partially wetting drop into an inert gas. We take kinetic effects into account through a linear constitutive law that states that the mass flux through the drop surface is proportional to the difference between the vapour concentration in equilibrium and that at the interface. Provided that the vapour concentration is finite, our model leads to a finite mass flux in contrast to the contact-line singularity in the mass flux that is observed in more standard models that neglect kinetic effects. We perform a local analysis near the contact line to investigate the way in which kinetic effects regularize the mass-flux singularity at the contact line. An explicit expression is derived for the mass flux through the free surface of the drop. A matched-asymptotic analysis is used to further investigate the regularization of the mass-flux singularity in the physically relevant regime in which the kinetic timescale is much smaller than the diffusive one. We find that the effect of kinetics is limited to an inner region near the contact line, in which kinetic effects enter at leading order and regularize the mass-flux singularity. The inner problem is solved explicitly using the Wiener–Hopf method and a uniformly valid composite expansion is derived for the mass flux in this asymptotic limit.

Thin polycrystalline films based on PbSnAgTe (LATT) compounds on mica-muscovite substrates are obtained. The dependences of conductivity, mobility of current carriers and specific thermoelectric power on temperature for these condensates are investigated. It is established that the mechanisms of transport of carriers on the intergrain boundaries dominate at low temperatures, and at higher temperatures the charge transport is determined by the volume of grain. The predominant scattering mechanism at higher temperatures is scattering on acoustic phonons. В работе получены тонкие поликристаллические пленки на основе соединений PbSnAgTe (LATT) на подложках из слюды-мусковит. Исследована зависимость проводимости, подвижности носителей тока и удельной термоэлектрической мощности от температуры данных конденсатов. Установлено, что механизмы переноса носителей тока на межзеренних границах доминируют при низких темпера- турах, а при более высоких темперетурах перенос заряда определяется объемом зерна. Преобладаю- щим механизмом рассеяния при высоких температурах является рассеяние на акустических фононах. В роботі отримано тонкі полікристалічні плівки на основі сполук PbSnAgTe (LATT) на підкладках зі слюди-мусковіт. Досліджено залежність провідності, рухливості носіїв струму та питомої термоелек- тричної потужності від температури для даних конденсатів. Встановлено, що механізми перенесення носіїв струму на міжзеренних межах домінують при низьких температурах, а при вищих температу- рах перенесення заряду визначається об’ємом зерна. Переважаючим механізмом розсіяння при ви- щих температурах є розсіяння на акустичних фононах.

This study presents the carbon, oxygen, and magnesium isotope compositions of two modern brachiopods, Terebratalia transversa and Frieleia halli, and one fossil specimen (2.3 Ma), Terebratula scillae. The aim of this study is to investigate the variability of these isotopic compositions and to evaluate the potential of brachiopods as a proxy of past seawater delta Mg-26 values. The two investigated brachiopod shells present the same range of delta(26)Mgvariation (up to 2%). This variation cannot be ascribed to changes in environmental parameters (temperature or pH). As has been previously observed, the primary layer of calcite shows the largest degree of oxygen and carbon isotope disequilibrium relative to seawater. In contrast, the delta Mg-26 value of the primary layer is comparable to that of the secondary calcite layer value. In both T. scillae and T. transversa, negative trends are observable between magnesium isotopic compositions and oxygen and carbon isotopic compositions. These trends can be explained by kinetic effects linked to changes in growth rate during the brachiopod life. The innermost calcite layer of T. transversa is in isotopic equilibrium for both oxygen and magnesium and could therefore be the best target for reconstructing past delta Mg-26 values of seawater. (C) 2016 Elsevier B.V. All rights reserved.

The multiscale method for computational fluid dynamics (CFD) is proposed to solve viscous flow problems at high Reynolds numbers with a thin boundary layer. This method is a physics-based model, uses generalized hydrodynamic equations proposed by Alexeev (1994), and can be interpreted as a regularization of the Navier-Stokes equations. Numerical solutions using this approach compare favorably with experimental data for the cases we considered for different flow problems in the range of Reynolds number from Re = 3200 to 1,000,000. The method is discussed and numerical solutions are compared with the experimental data for a 3D driven cavity flow at Re = 3200 and 10,000, 2D backward facing step flow at Re = 44,000, 2D channel flow at Re number up to 1 0 6 ; and a 3D thermal convection in a cylinder at Ra = 1000 to 150,000. Comparison with the analytical asymptotic solution is provided for a thermal convection, in the electrically conducting fluid suppressed by a strong magnetic field at Hartman numbers Ha up to 20,000. This multiphysics model is not a turbulence model, and no additional equations are introduced. Kinetic effects (small flow scales) are successfully captured with new terms introduced into the governing equations, and the derived small scale of turbulence compares well with observed in the experiments by Koseff and Street (1984).

Si bien la dinámica macroscópica de los plasmas en el medio interplanetario se estudiaadecuadamente a través de una descripción magnetohidrodinámica (MHD),a escalas más peque˜nas comienzan a manifestarse efectos cinéticos que producenconsecuencias observables. La presente Tesis propone investigar y entender algunosfenómenos físicos que requieren apartarse de la descripción MHD tradicional,tales como el efecto Hall y la inercia electrónica. En particular, se estudiarála generación y distribución de ondas de ultra-baja frecuencia asociadas alas magnetosferas planetarias, la importancia de la inercia electrónica en procesosde reconexión magnética no-colisional y el estudio del espectro de energía electromagnética en las peque˜nas escalas en el viento solar. El estudio teórico-numéricode estos fenómenos se complementará con el análisis de mediciones in-situ desatélites orbitando alrededor de planetas con campo magnético intrínseco, como la Tierra o Saturno. Palabras claves: magnetohidrodinámica, efectos cinéticos, turbu-lencia, reconexión magnética, ondas de ultra-baja frequencia The one-fluid magnetohydrodynamics (MHD) describes space plasma phenomenaat macroscopic temporal and spatial scales. However, this description is no adequatewhen small-scale processes become significant. In this Thesis, we theoreticallydescribe small-scale plasma processes observed in different regions of the interplanetarymedium. In particular, we focus our attention on the turbulent nature of thesolar wind, collisionless magnetic reconnection, and the generation and distributionof ultra-low frequency waves in planetary foreshocks. The theoretical andnumerical study will be complemented with the analysis of in-situ measurementsprovided by Cassini and Cluster spacecrafts. Keywords: magnetohydrodynamics, kinetic effects, turbulence, mag-netic reconnection, ultra-low frequency waves Fil: Andrés, Nahuel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

International audience; During the summer 2012, we carried out continuous measurements of the isotopic composition (δ) of water vapor over the near-surface subtropical North Atlantic Ocean (STRASSE cruise). In this region of excess evaporation, we investigate the control of evaporation and mixing with a lower troposphere-derived, isotopically depleted air mass on the near-surface δ. We use a simple model to simulate the near-surface δ as the result of a two end-member mixing of the evaporative flux with free tropospheric air. The evaporative flux δ was estimated by the Craig and Gordon equation while the δ of the lower troposphere was taken from the LMDZ-iso global atmospheric circulation model. This simulation considers instantaneous mixing of lower tropospheric air with the evaporated flux and neglects lateral advection. Despite these simplifications, the simulations allow to identify the controls on the near-surface δ. The d-excess variability is largely a consequence of varying kinetic effects during evaporation, even during a convection event when the input of tropospheric vapor was strong. Kinetic effects and mixing processes affect simultaneously the near-surface δ and result in the vapor occupying distinct domains in the δ18O-δD space. The relative humidity-d-excess relationship shows that the closure assumption overestimates the d-excess variability at short time scales (less than a day). We interpret this as due to an effect of the residence time of the near-surface water vapor on the d-excess. Finally, we highlight the importance of reproducing mixing processes in models simulating isotopes over the subtropical North Atlantic Ocean and propose an extension of the closure assumption for use in initial conditions of distillation calculations.

10.1021/jz500790b Experimental measurements for a variety of surfactants unexpectedly show that the critical micelle concentration (CMC) becomes constant with respect to increasing the size of the hydrophobic tail. This observation disagrees with theoretical models where it is expected to continue to decrease exponentially. Because of the lack of a satisfactory explanation for such a discrepancy from theory, we have studied these systems using a coarse-grained model within the single-chain mean field (SCMF) theory combined with relevant micellar kinetic effects. In particular, a microscopic model for poly(ethylene oxide) alkyl ether was applied to describe a series of nonionic gemini surfactants. When kinetic effects are used to correct the equilibrium CMC values from the SCMF scheme together with the loss of surfactants due to adsorption on the experimental recipient, it is possible to reproduce the correct order of magnitude of the experimental CMC results. Hence it appears that the experimental values disagree with the theoretical predictions because they are not true equilibrium values due to the fact that the time scales for these low CMC values become astronomically large.

We present a detailed study of intermittency in the velocity and magnetic field fluctuations of compressible Hall-magnetohydrodynamic turbulence with an external guide field. To solve the equations numerically, a reduced model valid when a strong guide field is present is used. Different values for the ion skin depth are considered in the simulations. The resulting data is analyzed computing field increments in several directions perpendicular to the guide field, and building structure functions and probability density functions. In the magnetohydrodynamic limit we recover the usual results with the magnetic field being more intermittent than the velocity field. In the presence of the Hall effect, field fluctuations at scales smaller than the ion skin depth show a substantial decrease in the level of intermittency, with close to monofractal scaling., 10 pages, 8 figures

Heating of polycrystalline cis aquabis(L-valinato)copper(II) at 90 °C resulted in a dehydrated powder. Recrystallization from aqueous solution of the obtained product yielded anhydrous trans bis(L-valinato)copper(II). The X-ray crystal and molecular structures of trans bis(L-valinato)copper(II) and cis aquabis(L-valinato)copper(II) are presented. Molecular modeling calculations were attempted to resolve factors that influenced the isomerization and crystallization of either the aqua cis- or the anhydrous trans-isomer. Conformational analyses of trans- and cis-isomers were completed in vacuo and in crystal by molecular mechanics, and in aqueous solution by molecular dynamics (MD) simulations using the same force field. Although the conformers with trans-configuration are the most stable in vacuo, those with cis-configuration form more favorable intermolecular interactions. Consequently, both cis- and trans-isomers are predicted to be present in aqueous solution. According to the crystal structure simulations and predictions, cis-isomer requires water molecules to form energetically more stable crystal packings than trans-isomer. The MD modeling of the self-assembly of 16 bis(L-valinato)copper(II) complexes in aqueous solution for the first time predicted the crystallization nucleus formation to proceed from monomers to oligomers by Cu-to-O(carboxylato) and/or N-H···O(carboxylato) weak bonds; these oligomers then bind together via water molecules until they acquire the right positions for noncovalent bonding like in the experimental crystal structures. Fifty-nanosecond MD simulations accomplished for a system consisting of equal numbers of complexes and water molecules at 298 and 370 K suggested complete cis-to-trans transformation at the higher temperature. Prevalence of either cis- or trans-conformers in water upon dissolvation may explain the crystallization results.

Висвітлено основні віхи життєвого шляху відомого вченого фізика професора А. В. Федосова.;The paper presents the career and scientific achievements of well-known physicist Professor Anatolyj Fedosov.

Step instability and surface mass transport strongly influence the kinetics of the two- to three-dimensional (2D-3D) transition in InAs/GaAs self-assembly epitaxy. In this paper we report evidence of the step erosion of quantum dots (QDs) nucleated on step edges for samples having different surface morphologies and the explosive nucleation of 3D QDs triggered by it. Related issues such as the temperature dependence of the critical thickness, the volume dependence of the surface mass transport, and the scaling behaviour are illustrated by means of RHEED and AFM measurements and data analysis for small increments of InAs coverage throughout the 2D-3D transition.

QC 20120528

International audience; This study aimed to investigate the environmental controls on the oxygen isotope composition of shells of the European abalone, Haliotis tuberculata. Seasonal delta O-18 profiles from the outer prismatic layer of four abalone shells, collected live in northwest Brittany (France) in 2002 and 2012, were compared to local temperatures and salinities. According to the findings herein, delta O-18 variations in abalone shells corresponded to seasonal variations, and thus, shell composition represented a reliable tool for aging and growth studies. Seawater temperatures estimated from the abalone collected in 2012 reflected the in situ measured temperatures, but the reconstructed temperatures from shells of the three specimens collected in 2002 deviated from measured temperatures by 2.5 degrees C. This overestimation of temperatures corresponded to a "kinetic effect" related to very high annual abalone growth rates; thus, it could be corrected by applying +053%. to the delta O-18(shell). This methodology was then applied to a fossil (6000 cal yr BP) collected in the Bay of Biscay. Given the worldwide distribution of both live and fossilized abalones, the results of the present study showed that this genus represents a promising paleoclimatic tool.