Kinetics and mechanism of the reaction between atomic chlorine and dimethyl selenide; comparison with the reaction between atomic chlorine and dimethyl sulfide

Dimethyl selenide is the most abundant gaseous selenium species in marine environments. In this work, the value of the rate coefficient for the gas-phase reaction between dimethyl selenide and Cl atoms has been determined for the first time. The value of the second-order rate coefficient obtained was (5.0±1.4)×10–10 cm3 molecule–1 s–1. The very fast nature of the reaction means that, when estimating the lifetime of dimethyl selenide in the atmosphere, loss due to reaction with Cl atoms should be considered along with loss due to reaction with O3 and with OH and NO3 radicals. Analysis of the available kinetic data suggests that at 760 Torr the dominant reaction pathway for the reaction of Cl atoms with dimethyl selenide will be the addition of Cl to the Se atom forming an adduct of the type CH3Se(Cl)CH3. Theoretical calculations, at the B3LYP/6-311++G(2df,p)//B3LYP/6-311++G(d,p) level of theory, show that at 298 K the value of rH for the formation of the adduct is –111.4 kJ mol–1. This value may be compared to –97.0 kJ mol–1, the value calculated for rH for the formation of the analogous sulfur adduct, CH3S(Cl)CH3, following the reaction between Cl atoms and dimethyl sulfide. Variational RRKM theory was used to predict the thermal decomposition rates of the two adducts back to starting materials. The estimated rate constant for the decomposition of the selenium adduct to the reactants is 5×10–5 s–1, compared to 0.02 s–1 in the case of the sulfur adduct. However, our calculations suggest that the CH3Se(Cl)CH3 adduct, which is initially formed highly excited, will not be stabilised under atmospheric conditions, but rather will decompose to yield CH3SeCl and CH3, a process that is calculated to be exothermic with respect to the initial reactants by 5.8 kJ mol–1. The formation of CH3SCl and CH3 from the sulfur adduct, on the other hand, is endothermic by 20.8 kJ mol–1 with respect to the initial reactants, and is thus not expected to occur

Volatile composition of Red Mencia and Souson cultivars from Rias Baixas and Valdeorras AOC (NW Spain)

Mencía and Sousón are two red Vitis vinifera cultivars grown in two geographic areas from Galicia (NW Spain), Appellation of Origin Controlled Valdeorras and Rías Baixas. Valdeorras AOC is situated in south east Galicia, with Continental climate, slate soil, gentle temperature and rainfall and Rías Baixas AOC is located in the southwest Galicia, near of the sea, with Atlantic climate, siliceous soil, and slightly higher temperature and rainfall than the first one. The aim of this study was to carry out a first approximation to determinate the influence of terroir on volatile composition of these red cultivars grown in Galicia. Grapes of Mencía and Sousón, collected in 2009 vintage, were crushed and the musts volatiles were extracted using Solid Phase Extraction (SPE). The identification and quantification was performed by gas chromatography-mass spectrometry (GC-MS) in free and bound form. The results showed a greater effect of terroir in bound compounds (alcohols, volatile phenols, C13-norisoprenoids and volatile fatty acids) between geographic areas for the two cultivars studied. In free fraction C6-compounds and carbonyl compounds showed variability between geographic areas for the cultivars

History states of one-dimensional quantum walks

We analyze the application of the history state formalism to quantum walks. The formalism allows one to describe the whole walk through a pure quantum history state, which can be derived from a timeless eigenvalue equation. It naturally leads to the notion of system-time entanglement of the walk, which can be considered as a measure of the number of orthogonal states visited in the walk. We then focus on one-dimensional discrete quantum walks, where it is shown that such entanglement is independent of the initial spin orientation for real Hadamard-type quantum coins and real initial states (in the standard basis) with definite site-parity. Moreover, in the case of an initially localized particle it can be identified with the entanglement of the unitary global operator that generates the whole history state, which is related to its entangling power and can be analytically evaluated. Besides, it is shown that the evolution of the spin subsystem can also be described through a spin history state with an extended clock. A connection between its average entanglement (over all initial states) and that of the operator generating this state is also derived. A quantum circuit for generating the quantum walk history state is as well provided.Comment: 12 pages, 7 figure

Development of Genetic Tools for the Manipulation of the Planctomycetes

Bacteria belonging to the Planctomycetes, Verrucomicrobia, Chlamydiae (PVC) superphylum are of interest for biotechnology, evolutionary cell biology, ecology, and human health. Some PVC species lack a number of typical bacterial features while others possess characteristics that are usually more associated to eukaryotes or archaea. For example, the Planctomycetes phylum is atypical for the absence of the FtsZ protein and for the presence of a developed endomembrane system. Studies of the cellular and molecular biology of these infrequent characteristics are currently limited due to the lack of genetic tools for most of the species. So far, genetic manipulation in Planctomycetes has been described in Planctopirus limnophila only. Here, we show a simple approach that allows mutagenesis by homologous recombination in three different planctomycetes species (i.e., Gemmata obscuriglobus, Gimesia maris, and Blastopirellula marina), in addition to P. limnophila, thus extending the repertoire of genetically modifiable organisms in this superphylum. Although the Planctomycetes show high resistance to most antibiotics, we have used kanamycin resistance genes in G. obscuriglobus, P. limnophila, and G. maris, and tetracycline resistance genes in B. marina, as markers for mutant selection. In all cases, plasmids were introduced in the strains by mating or electroporation, and the genetic modification was verified by Southern Blotting analysis. In addition, we show that the green fluorescent protein (gfp) is expressed in all four backgrounds from an Escherichia coli promoter. The genetic manipulation achievement in four phylogenetically diverse planctomycetes will enable molecular studies in these strains, and opens the door to developing genetic approaches not only in other planctomycetes but also other species of the superphylum, such as the Lentisphaerae.ER-M and DPD are supported by the Spanish Ministry of Economy and Competitivity (Grant BFU2013-40866-P) and the Junta de Andalucía (CEIC Grant C2A program to DPD). IC and ES are supported by the Spanish Ministry of Economy and Competitivity (Grant BIO2014-57545-R).Peer reviewedPeer Reviewe

Singularity Structure, Symmetries and Integrability of Generalized Fisher Type Nonlinear Diffusion Equation

In this letter, the integrability aspects of a generalized Fisher type equation with modified diffusion in (1+1) and (2+1) dimensions are studied by carrying out a singularity structure and symmetry analysis. It is shown that the Painlev\'e property exists only for a special choice of the parameter ($m=2$). A B\"acklund transformation is shown to give rise to the linearizing transformation to the linear heat equation for this case ($m=2$). A Lie symmetry analysis also picks out the same case ($m=2$) as the only system among this class as having nontrivial infinite dimensional Lie algebra of symmetries and that the similarity variables and similarity reductions lead in a natural way to the linearizing transformation and physically important classes of solutions (including known ones in the literature), thereby giving a group theoretical understanding of the system. For nonintegrable cases in (2+1) dimensions, associated Lie symmetries and similarity reductions are indicated.Comment: 8 page

Hilbert-Schmidt Separability Probabilities and Noninformativity of Priors

The Horodecki family employed the Jaynes maximum-entropy principle, fitting the mean (b_{1}) of the Bell-CHSH observable (B). This model was extended by Rajagopal by incorporating the dispersion (\sigma_{1}^2) of the observable, and by Canosa and Rossignoli, by generalizing the observable (B_{\alpha}). We further extend the Horodecki one-parameter model in both these manners, obtaining a three-parameter (b_{1},\sigma_{1}^2,\alpha) two-qubit model, for which we find a highly interesting/intricate continuum (-\infty < \alpha < \infty) of Hilbert-Schmidt (HS) separability probabilities -- in which, the golden ratio is featured. Our model can be contrasted with the three-parameter (b_{q}, \sigma_{q}^2,q) one of Abe and Rajagopal, which employs a q(Tsallis)-parameter rather than $\alpha$, and has simply q-invariant HS separability probabilities of 1/2. Our results emerge in a study initially focused on embedding certain information metrics over the two-level quantum systems into a q-framework. We find evidence that Srednicki's recently-stated biasedness criterion for noninformative priors yields rankings of priors fully consistent with an information-theoretic test of Clarke, previously applied to quantum systems by Slater.Comment: 26 pages, 12 figure

La variedad Albariño en el Valle del Salnés (D.O. Rias Baixas)

El Valle del Salnés es la subzona de la D.O. Rías Baixas con más del 50% de la superficie vitícola de la D.O.. Dentro de las variedades de uva cultivadas en esta D.O., la Albariño (Vitis vinifera L.) se destaca como la más representativa, suponiendo un 95% de la producción total (Consello Regulador D.O. Rías Baixas, datos cosecha 2009). En el presente trabajo, se realizó una caracterización aromática de la uva Albariño producida en el Valle del Salnés en la cosecha 2009