Hydration water and ionic aggregation in aqueous solutions of imidazolium-based protic ionic liquids

Water molecules, present as additive or as contaminant of Protic Ionic Liquids (PILs), can compete for the hydrogen bond sites leading to important modifications of the local order of these liquids and to the modulation of their physical–chemical properties. In this work, aqueous solutions of a set of N-methylimidazolium-based PILs [MIM][X] (X = NO3-- , TfO-- , HSO4-- , and Cl-- ) were investigated by deep UV Resonance Raman (UVRR) spectroscopy in the water-rich domain where ionic aggregates and bulk-like water coexist. A differential method was used to analyze the OH stretching profile to extract the so-called solute-correlated (SC) spectrum, which is particular informative of the hydration features of the PILs. Moreover, specific bands of the cation, sensitive to the hydrogen bonding, were comparatively investigated. The progressive evolution from solvent-separated ion pairs (SIP) and/or solvent-shared ion pairs (SSIP) to contact ion pairs (CIP) and/or larger ionic aggregates can be monitored as a function of the hydration level, in the water-rich domain. Our approach showed that, in the highly diluted regime, the hydration environment around the [MIM] cation does not depend on the type of anion. Moreover, [MIM][NO3] and [MIM][TfO] showed cation-water (ionic) H-bonds at the NH site stronger than the cation–anion (double-ionic) ones. The analysis of SC Raman spectra points out the formation of cation–anion Hbonds (through the CH ring groups), stronger than cation-water ones, upon PILs concentration increase, especially evident in the case of [MIM][Cl]. The H-bond strength between the anion and hydration water is found to decrease following the order: [Cl] ~ [HSO4] > [NO3] > [TfO]. Chloride ions tend to perturb a larger number of water molecules than the other anions. The number of perturbed water molecules decreases at increasing PIL concentration, showing a larger dependence for [MIM][Cl], consistently with its larger propensity to form ionic aggregates. The unique response of [MIM][Cl] to hydration found by analyzing SC-UVRR data is related to the synergy of different factors such as the anion reduced size (higher charge density), spherical symmetry, and high H-bond basicity

Reddening, Absorption, and Decline Rate Corrections for a Complete Sample of Type Ia Supernovae leading to a Fully Corrected Hubble Diagram to v<30,000kms-1

Photometric BVI and redshift data corrected for streaming motions are compiled for 111 "Branch normal", 4 1991T-like, 7 1991bg-like, and 2 unusual SNe Ia. Color excesses E(B-V)host of normal SNe Ia, due to the absorption of the host galaxy, are derived by three independent methods leading to the intrinsic colors at maximum of (B-V)00=-0.024, and (V-I)00=-0.265 if normalized to a common decline rate of Dm_15=1.1. The strong correlation between redshift absolute magnitudes (based on Ho=60), corrected only for the extrinsic Galactic absorption, and the derived E(B-V)host leads to well determined, yet abnormal absorption-to-reddening ratios of R_BVI=3.65, 2.65, and 1.35. Comparison with the canonical Galactic values of 4.1, 3.1, 1.8 forces the conclusion that the law of interstellar absorption in the path length to the SN in the host galaxy is different from the local Galactic law. Improved correlations of the fully corrected absolute magnitudes with host galaxy type, decline rate, and intrinsic color are derived. The four peculiar 1991T-type SNe are significantly overluminous as compared to Branch-normal SNe Ia. The overluminosity of the seven 1999aa-like SNe is less pronounced. The seven 1991bg-types in the sample constitute a separate class of SNeIa, averaging in B two magnitudes fainter than the normal Ia. New Hubble diagrams in BVI are derived out to ~30,000kms-1 using the fully corrected magnitudes and velocities, corrected for streaming motions. Nine solutions for the intercept magnitudes in these diagrams show extreme stability at the 0.04 level using various subsamples of the data. The same precepts for fully correcting SN magnitudes we shall use for the luminosity recalibration of SNe Ia in the forthcoming final review of our HST Cepheid-SN experiment for the Hubble constant.Comment: 49 pages, 15 figures, 8 tables, accepted for publication in the Astrophysical Journa

Previsão de Carga para Configuração Dinâmica de Aglomerados de Servidores Web

Atualmente, há uma crescente conscientização sobre computação verde em sistemas computacionais. Uma das grandes fontes de demanda energética nesses sistemas são os aglomerados de servidores web. Este trabalho avalia uma política para antecipar a carga e configurar o número de servidores ativos de forma que seja mantido uma qualidade de serviço satisfatória, enquanto se reduz o uso de energia. Experimentos são feitos em um protótipo de cluster para validar a técnica empregada

TEMPO-oxidized cellulose nanofibril/polyvalent cations hydrogels: a multifaceted view of network interactions and inner structure

In the last years, hydrogels from renewable biopolymers and low-cost row materials are a hot topic for biomedical applications. In this context, cellulose nanofibrils are considered suitable building blocks for the synthesis of many biocompatible products, with a variety of chemical-physical properties. Herein we report a multi-technique and multi-scale study, from the molecular to the nanometric length scale, of the sol-gel transition observed in aqueous solutions of TEMPO-oxidized nano-sized cellulose fibrils (TOCNFs), when in the presence of polyvalent cations (Mg2+ and Ca2+). We combine the data from Small Angle Neutron Scattering (SANS), which provide information about the inner structure of the nanofibril, with those from UV Resonant Raman (UVRR) spectroscopy, which is a sensitive probe of the intra- and inter-molecular interactions in the gel and the liquid state. The transition between the gel and the liquid phases is investigated as a function of the concentration of both TOCNFs and cations, the nature of the latter, and the pH at which the phenomenon is observed. SANS analysis reveals that ion concentration induces an anisotropic swelling in the nanofibrils which, at the same time, become more and more flexible. The nanofibrils flexibility is also dependent on TOCNF concentration and pH value. UVRR allows us to elucidate the structural organization and hydrogen-bonding properties of water in aqueous TOCNF dispersions and gels, showing how water molecules partially lose their typical bulk-like tetrahedral organization when ions are added, and the gel phase is formed

Radio echo sounding data analysis of the Shackleton Ice Shelf

In this study, our initial results are presented for the interpretation of the radio echo sounding data collected over the Shackleton Ice Shelf and adjacent ice sheet (East Antarctica) during the 2003/2004 Australian- Italian expedition. The Shackleton Ice Shelf is one of the larger ice shelves of the East Antarctic Ice Sheet. The radar survey provided data relating to ice thickness and bed morphology of the outlet glaciers, and thickness of their floating portions. The glacier grounding lines were determined by assessment of the basal echo characters. The information derived is compared with data from the BEDMAP database and from other sources

Modelling aspects of terrestrial ecology in an italian endemic salamander, Salamandrina perspicillata

Density and other aspects of terrestrial activity were studied in a population of Salamandrina perspicillata from central Italy (Vejo Natural Park, province of Rome). Salamander density was studied by line-transect methodology with Distance modelling procedures. Linear distance of each salamander from water was also measured, as well as the correlations between population density, distance of salamanders from water, and some habitat variables. In total, a sample of 227 captures was collected and analysed. The distance of salamanders from water increased significantly with time (number of days after the beginning of the study, i.e. 13 April), considering either as dependent variable the mean distance of salamanders on each day of survey or the individual distances recorded for all the salamanders captured during the present investigation. After subdividing the stream into various sectors classifi ed on the basis of their morphological and habitat variables, a General Linear Model (full factorial design) showed that the salamander distance from water varied significantly among sectors of the stream, with also an effect of time elapsed since the first day of survey and an effect of stream sector*time. Estimated density varied remarkably with day-of-survey, ranging from 0 to over 55 individuals/ha. The mean density of salamanders was 24.6 ± 14.7 individuals/ha, similar to that of many other salamander species studied so far. According to both multivariate analyses and logistic regression models, two habitat variables (inclination of the slopes surrounding the stream and type of stream banks) significantly affected the population densityModélisation d'aspects de l'écologie terrestre d'une salamandre endémique italienne, Salamandrina perspicillata.- La densité et d'autres aspects de l'activité terrestre ont été étudiés dans une population de Salamandrina perspicillata du centre de l'Italie (parc naturel de Vejo, province de Rome). La densité des salamandres a été établie par la méthode des line-transects avec le logiciel Distance. La distance à l'eau de chaque individu a également été mesurée ainsi que les corrélations entre densité de population, distance à l'eau et diverses variables de l'habitat. Au total, un échantillon de 227 captures a été obtenu et analysé. La distance à l'eau s'est avérée croître significativement avec le temps (nombre de jours à partir du début de l'étude, c-à-d. le 13 avril), que l'on prenne tant comme variable indépendante la distance moyenne des individus établie chaque jour du suivi que les distances individuelles de toutes les salamandres enregistrées durant l'étude. Après subdivision du cours d'eau en secteurs classés en fonction de leur morphologie et de leurs variables d'habitat, un modèle général linéaire a montré que la distance à l'eau variait de manière significative entre les secteurs, avec aussi un effet temps écoulé depuis le premier jour de suivi et un effet secteur x temps. La densité estimée variait de manière remarquable de 0 à plus de 55 individus/ha selon le jour de suivi. La densité moyenne était de 24,6 ± 14,7 individus/ha, similaire à celle de beaucoup d'autres espèces de salamandres étudiées jusqu'à présent. Tant des analyses multivariées que des modèles de régression logistique ont montré que deux variables d'habitat (l'inclinaison des pentes entourant le cours d'eau et le type de bord du cours d'eau) affectaient de manière significative la densité de population

Adding diphenyl diselenide in the diets of quails improves the quality of meat.

Abstract: Diphenyl diselenide (Ph2Se2) is an organic selenium compound that is known for its antioxidant characteristics. Thus, the aim of this study was to evaluate whether Ph2Se2 in quail (Coturnix japonica) diets influences the oxidative/antioxidant status and meat quality. Materials and methods. Four diets (0; 0.3; 0.6; 0.9 ppm Ph2Se2) were provided to 56 male quails (Coturnix japonica) distributed in a completely randomized design with 14 repetitions in order to check whether (PhSe)2 would change their blood and tissue oxidative/antioxidant status, which would lead to an improvement in the meat quality. Results. Adding Ph2Se2 in diets led to increased antioxidant activity of enzymes such as catalase, superoxide dismutase, and glutathione peroxidase, which consequently reduced oxidative levels in blood and tissues. Besides that, we observed an improvement in the quail meat quality; in other words, we observed an increased ability to hold water, a reduction in water loss from cooking, and reduced intensity of the yellow color in the breasts of birds that were fed with Ph2Se2. Conclusions. Therefore, we concluded that the antioxidant defense improvement in tissues that was provided by Ph2Se2 has a beneficial effect on meat quality. Resumen: El diseleniuro de difenilo (Ph2Se2) es un compuesto de selenio orgánico que es conocido por sus características antioxidantes. Por lo tanto, el objetivo de este estudio fue evaluar si Ph2Se2 en las dietas de codorniz (Coturnix japonica) influye en el estado oxidativo/antioxidante y la calidad de la carne. Materiales y métodos. Se proporcionaron cuatro dietas (0; 0.3; 0.6; 0.9 ppm Ph2Se2) a 56 codornices machos (Coturnix japonica) distribuidas en un diseño completamente aleatorizado con 14 repeticiones para verificar si Ph2Se2 cambiaría su sangre y tejido oxidativo/antioxidante, estado, lo que llevaría a una mejora en la calidad de la carne. Resultados. La adición de Ph2Se2 en las dietas provocó un aumento de la actividad antioxidante de enzimas como la catalasa, la superóxido dismutasa y la glutatión peroxidasa, lo que redujo los niveles de oxidación en la sangre y los tejidos. Además de eso, observamos una mejora en la calidad de la carne de codorniz; en otras palabras, observamos una mayor capacidad para retener agua, una reducción en la pérdida de agua debido a la cocción y una menor intensidad del color amarillo en las mamas de las aves que fueron alimentadas con Ph2Se2. Conclusiones. Por lo tanto, concluimos que la mejora de la defensa antioxidante en los tejidos proporcionada por Ph2Se2 tiene un efecto beneficioso sobre la calidad de la carne

Interacting Preformed Cooper Pairs in Resonant Fermi Gases

We consider the normal phase of a strongly interacting Fermi gas, which can have either an equal or an unequal number of atoms in its two accessible spin states. Due to the unitarity-limited attractive interaction between particles with different spin, noncondensed Cooper pairs are formed. The starting point in treating preformed pairs is the Nozi\`{e}res-Schmitt-Rink (NSR) theory, which approximates the pairs as being noninteracting. Here, we consider the effects of the interactions between the Cooper pairs in a Wilsonian renormalization-group scheme. Starting from the exact bosonic action for the pairs, we calculate the Cooper-pair self-energy by combining the NSR formalism with the Wilsonian approach. We compare our findings with the recent experiments by Harikoshi {\it et al.} [Science {\bf 327}, 442 (2010)] and Nascimb\`{e}ne {\it et al.} [Nature {\bf 463}, 1057 (2010)], and find very good agreement. We also make predictions for the population-imbalanced case, that can be tested in experiments.Comment: 10 pages, 6 figures, accepted version for PRA, discussion of the imbalanced Fermi gas added, new figure and references adde

Microstructural differences in the thalamus and thalamic radiations in the congenitally deaf

There is evidence of both crossmodal and intermodal plasticity in the deaf brain. Here, we investigated whether sub-cortical plasticity, specifically of the thalamus, contributed to this reorganisation. We contrasted diffusion weighted magnetic resonance imaging data from 13 congenitally deaf and 13 hearing participants, all of whom had learnt British Sign Language after 10 years of age. Connectivity based segmentation of the thalamus revealed changes to mean and radial diffusivity in occipital and frontal regions, which may be linked to enhanced peripheral visual acuity, and differences in how visual attention is deployed in the deaf group. Using probabilistic tractography, tracts were traced between the thalamus and its cortical targets, and microstructural measurements were extracted from these tracts. Group differences were found in microstructural measurements of occipital, frontal, somatosensory, motor and parietal thalamo-cortical tracts. Our findings suggest there is sub-cortical plasticity in the deaf brain, and that white matter alterations can be found throughout the deaf brain, rather than being restricted to, or focussed in auditory cortex