Reactive Collisional Spectroscopy: Scalar and Vector InformationFrom Numerically Intensive Computing

Advances in computer technologies have made it possible to extend the numerical investigation of the detailed structure of reactive properties to several atom–diatom systems. This has allowed a better understanding of the energy structure of the reaction intermediate and of the role it plays when reaction occurs

Self-Diffusion in Nanofluids of Nonelongated Particles in the Dilute Limit

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] The dynamic features of a dilute suspension of nanoparticles (nanofuid) are fully modifed depending on the dominant particles slip mechanism acting in the suspension. Self-difusion efects in highly sheared diluted suspensions (entrance conditions and microapplications) can lead to a particles distribution fully diferent from the bulk one. The reported investigation proposes a model to determine the self-difusion of three-planes symmetric nonelongated particles inmersed in a sheared Stokes fow. The model is based on the real displacements between any pair of particles and an statistical approach to determine contact kinematic irreversibilities. According to the proposed model, the source of hydrodynamic irreversibility is closely related to the particles shape. This is clearly demonstrated through the application of the model to cubic particles. The main conclusion is that the particles shape plays a signifcant role in the dynamic behavior of the suspension and, as a result, in the self-difusion coefcient. The reported results arising from the cubic particles trajectories in a Stokes fow are reasonably close to the ones reported by Brady and Morris (J Fluid Mech, 348:103–139, 1997) for suspensions under high Pe number, and Zarraga and Leighton (Phys Fluids 13(3):565-577, 2001)The authors gratefully acknowledge the support given to the investigation reported herein by the Galician High Performance Computing Center (CESGA) and the Ministry of Economy and Competitiveness, Spain, through the Grant No. ENE2012-38326-C02-01. Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Natur

Reaction dynamics of the D+ + H2 system. A comparison of theoretical approaches

The dynamics of the deuteron-proton exchange D+ + H2 → HD + H+ reaction on its ground 11A′ potential energy surface has been the subject of a theoretical study for collision energies below 1.5 eV. The results obtained with three theoretical approaches: quasi-classical trajectory (QCT), statistical quasi-classical trajectory (SQCT), and accurate time-independent quantum mechanical (QM) calculations are compared in the range of collision energies from 5 meV to 0.2 eV. The QM calculations included all total angular momentum quantum numbers, J, up to Jmax ≈ 40 and all the Coriolis couplings. For higher collision energies, the comparison was restricted to the QCT and SQCT results given the enormous computational cost implied in the QM calculations. Reaction cross sections as a function of collision energy (excitation functions) for various initial rovibrational states have been determined and compared with the corresponding results for the endothermic H+ + D2 → HD + D + isotopic variant. The excitation function for the title reaction decays monotonically with collision energy as expected for an exothermic reaction without a barrier, in contrast to the behaviour observed in the mentioned H+ + D2 (v = 0, j ≤ 3). Reaction probabilities as a function of J (opacity functions) at several collision energies calculated with the different approaches were also examined and important differences between them were found. The effect of using the Gaussian binning procedure that preserves, to a large extent, the zero point energy, as compared to the standard histogram binning in the QCT calculations, is also examined. At low collision energy, the best agreement with the accurate QM results is given by the SQCT data, although they tend to overestimate the reactivity. The deviations from the statistical behaviour of the QCT data at higher energies are remarkable. Nevertheless, on the whole, the title reaction can be deemed more statistical than the H+ + D2 reaction. © Royal Society of Chemistry 2010.Peer Reviewe

Photodetachment spectrum of OHF-: Three-dimensional study of the heavy–light–heavy resonances

12 pages, 14 figures, 1 table.-- PACS nrs.: 82.30.Cf; 82.20.Kh; 31.15.Ar; 33.15.Mt; 33.80.Gj; 31.25.Eb; 31.50.Bc.In this work a simulation of the OHF- photodetachment spectrum is performed in a three-dimensional potential energy surface recently developed for OHF(3A''). The ground 2A' state potential of the anion is calculated in three dimensions based on accurate ab initio calculations and the reaction dynamics is studied using a wave packet method. The calculated spectrum shows a sequence of bands associated to vibrational HF(ν) up to ν = 3. Each band is formed by a continuous spectrum and resonant structures. These resonances are associated to the OH–F channel well of the 3A'' PES, in which fragmentation occurs through vibrational predissociation. Above the OH(ν = 0) threshold a new resonant pattern appears corresponding to heavy–light–heavy resonances. Special attention is paid to the assignment of these resonances because they mediate the reaction dynamics in the OH + F collision at low kinetic energies. The sequence of bands is in rather good agreement with that appearing in the experimental spectrum, especially at higher electron kinetic energies. At low kinetic energies, however, some other electronic states may contribute. The resonance structures might be washed out by the rotational average and the relatively low energy resolution of the experiment.This work has been supported by MCYT (Spain), under Grant Nos. BFM2001-2179, BQU2001-0152, and BQU2002-04462-C02-01.Peer reviewe

Determination of plasma melatonin levels by enzyme-linked inmunoabsobent assay (EIA) in turbot (Scophthalmus maximus L.) and tench (Tinca tinca L.)

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Dynamics and kinetics of the F + OH reaction on the ground triplet potential energy surface

MRCI electronic energy calculations have been carried out for the ground triplet state of the OHF reactive system. 8069 ab initio points have been fitted with a two- and three-body polynomial expansion in modified Rydberg coordinates and a high quality global potential energy surface (PES) was thus generated. On the PES, quasiclassical trajectory calculations were run to simulate existing kinetic and dynamic experimental data for the title reaction. The calculated and measured trends with temperature of the thermal rate coefficient and rovibrational energy distribution of the HF molecule satisfactorily compare and discrepancies are explained. © 2003 Elsevier B.V. All rights reserved.This work has been supported by DGICYT (Ministerio de Ciencia y Tecnolog ıa, Spain) under grants BQU2002-04462-C02-01,BQU2001-0152andBFM2001- 2179.Peer Reviewe

Quantum stereodynamics of the F+OH(v, j) reactive collision on the 1(3) A'' state

12 pages, 7 figures.The reactivity dependence on the k, j vector correlation for the title reaction is studied for j=1, 2, 3 by a quantum wavepacket method in a large range of translational energy on a recently obtained 3A'' adiabatic potential energy surface. It is found that the reaction is extraordinarily enhanced when initially k and j are perpendicular, or equivalently, when the OH internuclear vector is parallel to the initial relative velocity in the rotating body-fixed plane. Such a result is interpreted in terms of the kinematic constraints imposed by the small skew angle in heavy-light + heavy reactions, being a general situation in this kind of HL + H → H + LH reactions. The total reaction cross-sections obtained are in rather good agreement with quasiclassical results, especially as j increases. Finally, the rate constants obtained are compared with available experimental data at nearly room temperature.This work has been supported by Ministerio de Ciencia y Tecnología (Spain), under grant numbers BFM2001-2179, BQU2001-0152 and BQU2002-04462- C02-01. Also, partial support from a Research Network HPRN-CT-1999-2005 (THEONET II) is acknowledged.Peer reviewe

Effects of melatonin implants on reproduction and growth of turbot broodstock

The effect of 18 mg. melatonin (MLT) implants on thereproductive performance of turbot (Scophthalmus maximusL.) broodstock was determined in 20 females and 12 males. Implantedanimals showed supra-physiological plasma MLT concentrations during threemonthsafter implantation, being at that time about one hundred times higher thandiurnal MLT concentrations. Direct effects of MLT implants were observed ongonadal maturation of turbot females three months after implantation (P <0.01), although the faster ovarian response to increasing photoperiod was notconsistent and no differences were detected at the final reproductiveperformance. MLT implants had a positive effect on turbot male reproductivefeatures, since gonadal recrudescence started 45 days earlier (P < 0.05)showing a trend towards higher spermatozoa concentration. Further research isadvisable to ascertain the MLT dose required for and time of implantation inturbot broodstock.Versión del editor0,912

Single-cell mtDNA heteroplasmy in colorectal cancer

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGHuman mitochondria can be genetically distinct within the same individual, a phenomenon known as heteroplasmy. In cancer, this phenomenon seems exacerbated, and most mitochondrial mutations seem to be heteroplasmic. How this genetic variation is arranged within and among normal and tumor cells is not well understood. To address this question, here we sequenced single-cell mitochondrial genomes from multiple normal and tumoral locations in four colorectal cancer patients. Our results suggest that single cells, both normal and tumoral, can carry various mitochondrial haplotypes. Remarkably, this intra-cell heteroplasmy can arise before tumor development and be maintained afterward in specific tumoral cell subpopulations. At least in the colorectal patients studied here, the somatic mutations in the single-cells do not seem to have a prominent role in tumorigenesis.Agencia Estatal de Investigación | Ref. PID2019-106247GB-I0