PRECONCENTRATION OF COPPER FROM DIFFERENT SAMPLES BY DISPERSIVE LIQUID-LIQUID MICROEXTRACTION

Sample preparation is a critical step of any analytical protocol. Nowadays the goals to be reached are the best results, in the shortest time, with minimal contamination, low reagent consumption and generation of minimal waste. Dispersive liquid-liquid microextraction is a miniaturized sample preparation procedure inside Green Chemistry because the low volume of dissolvent employed. All parameters that influence on the preconcentration of copper have been optimized. The detection limit was 7.9 μg L-1. The proposed method was successfully applied to the preconcentration and determination of copper in food, vegetation, and water samples and in two standard reference materials

Evaluation of patient visual comfort and repeatability of refractive values in non-presbyopic healthy eyes

•AIM: To evaluate the intra-operator repeatability in healthy subjects using the WAM-5500 auto-kerato/refractometer and the iTrace aberrometer, to compare the refractive values and the subjective refraction obtained with both devices and to determine which of these three spherocylindrical corrections allows the subject to achieve the best visual comfort. •METHODS: Forty-two non-presbyopic healthy eyes of 42 subjects were enrolled in this prospective study. Refractive values were compared, evaluating the repeatability, the relationship between the methods and the best visual comfort obtained. •RESULTS: Sphere, cylinder and axis results showed good intraclass correlation coefficients (ICC); the highest ICC was obtained using the spherical refraction with the autorefractometer and the aberrometer, achieving levels of 0.999 and 0.998, respectively. The power vector (PV) was calculated for each refraction method, and the results indicated that there were no statistically significant differences between them (P>0.05). Direct comparison of PV measurements using the three methods showed that aberrometer refraction gave the highest values, followed by the subjective values; the autorefractometer gave the lowest values. The subjective method correction was most frequently chosen as the first selection. Equal values were found for the autorefractometer and the aberrometer as the second selection. •CONCLUSION: The iTrace aberrometer and the WAM-5500 auto-kerato/refractometer showed high levels of repeatability in healthy eyes. Refractive corrections with the aberrometer, the autorefractometer and subjective methods presented similar results, but spherocylindrical subjective correction was the most frequently selected option. These technologies can be used as complements in refractive evaluation, but they should not replace subjective refraction

Easy to synthesize, robust organo-osmium asymmetric transfer hydrogenation catalysts

Asymmetric transfer hydrogenation (ATH) is an important process in organic synthesis for which the Noyori-type RuII catalysts [(arene)Ru(Tsdiamine)] are now well established and widely used. We now demonstrate for the first time the catalytic activity of the osmium analogues. X-ray crystal structures of the 16-electron OsII catalysts are almost identical to those of RuII. Intriguingly the precursor complex was isolated as a dichlorido complex with a monodentate amine ligand. The OsII catalysts are readily synthesised (within 1 h) and exhibit excellent enantioselectivity in ATH reactions of ketones

Asymmetric transfer hydrogenation by synthetic catalysts in cancer cells

Catalytic anticancer metallodrugs active at low doses could minimise side-effects, introduce novel mechanisms of action which combat resistance, and widen the spectrum of anticancer drug activity. We have used new highly-stable chiral half-sandwich organometallic Os(II) arene sulfonyl diamine complexes, [Os(arene)(TsDPEN)] to achieve highly enantioselective reduction of pyruvate, a key intermediate in metabolic pathways, both in aqueous model systems and in human cancer cells, using non-toxic concentrations of sodium formate as a hydride source. Importantly the catalytic mechanism generates selectivity towards ovarian cancer cells versus non-cancerous fibroblasts (both ovarian and lung), which are commonly used as models of healthy proliferating cells. The formate precursor N-formylmethionine was explored as an alternative to formate in PC3 prostate cancer cells, which are known to over-express a deformylase enzyme. Transfer hydrogenation catalysts generating reductive stress in cancer cells offer a ground-breaking new approach to cancer therapy

The relationship of the atlantic diet with cardiovascular risk factors and markers of arterial stiffness in adults without cardiovascular disease

Background: Studying the adherence of the population to the Atlantic Diet (AD) could be simplified by an easy and quickly applied dietary index. The aim of this study is to analyse the relationship of an index measuring compliance with recommendations regarding the Atlantic diet and physical activity with cardiovascular disease risk factors, cardiovascular risk factors, obesity indexes and arterial stiffness markers. Methods: We included 791 individuals from the EVIDENT study (lifestyles and arterial ageing), (52.3 ± 12 years, 61.7% women) without cardiovascular disease. Compliance with recommendations on AD was collected through the responses to a food frequency questionnaire, while physical activity was measured by accelerometer. The number of recommendations being met was estimated using a global scale between 0 and 14 points (a higher score representing greater adherence). Blood pressure, plasma lipid and glucose values and obesity rates were measured. Cardiovascular risk was estimated with the Framingham equation. Results: In the overall sample, 184 individuals (23.3%) scored between 0–3 on the 14-point index we created, 308 (38.9%) between 4 and 5 points, and 299 (37.8%) 6 or more points. The results of multivariate analysis yield a common tendency in which the group with an adherence score of at least 6 points shows lower figures for total cholesterol (p = 0.007) and triglycerides (p = 0.002). Similarly, overall cardiovascular risk in this group is the lowest (p < 0.001), as is pulse wave velocity (p = 0.050) and the mean values of the obesity indexes studied (p < 0.05 in all cases). Conclusion: The rate of compliance with the Atlantic diet and physical activity shows that greater adherence to these recommendations is linked to lower cardiovascular risk, lower total cholesterol and triglycerides, lower rates of obesity and lower pulse wave velocity values

Experimental investigation of a thermal storage system using phase change materials

A home-made heat exchanger (HE), used in the evaluation of the performance of different phase change materials (PCMs), was designed, mounted and operated. The HE unit was used as a heat thermal storage system for recovering the residual energy coming from a hydrogen cycle, which could be in turn used in building air-conditioning facilities. Four PCMs (Rubitherm® RT28, Rubitherm® RT48, Rubitherm® RT55 and Mikrocaps PCM35; the latter supplied as a slurry of microcapsules) was selected for their suitable thermal properties. Water was used as the heat transfer fluid (HTF) while the PCM was tightly stored inside the shell. Among all the studied PCMs, Rubitherm® RT48 presented the best thermal performance since it accumulated the maximum amount of energy. The influence of the HTF flow rate on the thermal performance of the shell and tube HE was also evaluated. Low HTF flow rates led to high values of heat transferred. Finally, different operation modes (watertight and countercurrent PCM flow) were compared by using Mikrocaps PCM35. PCM countercurrent flow system showed to be the best experimental set-up configuration system for energy transfer, reaching values of heat accumulation about 71% higher than that shown by the watertight mode.Se diseñó, montó y operó un intercambiador de calor casero (HE), utilizado en la evaluación del desempeño de diferentes materiales de cambio de fase (PCM). La unidad HE se utilizó como sistema de almacenamiento térmico de calor para recuperar la energía residual procedente de un ciclo de hidrógeno, que a su vez podría utilizarse en la construcción de instalaciones de aire acondicionado. Se seleccionaron cuatro PCM (Rubitherm® RT28, Rubitherm® RT48, Rubitherm® RT55 y Mikrocaps PCM35; este último suministrado como una suspensión de microcápsulas) por sus propiedades térmicas adecuadas. Se usó agua como fluido de transferencia de calor (HTF) mientras que el PCM se almacenó herméticamente dentro de la carcasa. Entre todos los PCM estudiados, Rubitherm® RT48 presentó el mejor desempeño térmico ya que acumuló la máxima cantidad de energía. También se evaluó la influencia del caudal de HTF en el rendimiento térmico de la carcasa y el tubo HE. Las bajas tasas de flujo de HTF condujeron a altos valores de transferencia de calor. Finalmente, se compararon diferentes modos de operación (flujo PCM estanco y contracorriente) utilizando Mikrocaps PCM35. El sistema de flujo a contracorriente PCM demostró ser el mejor sistema de configuración experimental para la transferencia de energía, alcanzando valores de acumulación de calor un 71% superiores a los mostrados por el modo estanco

Discovery of the broad-lined Type Ic SN 2013cq associated with the very energetic GRB 130427A

Long-duration gamma-ray bursts (GRBs) at z < 1 are in most cases found to be accompanied by bright, broad-lined Type Ic supernovae (SNe Ic-BL). The highest-energy GRBs are mostly located at higher redshifts, where the associated SNe are hard to detect observationally. Here we present early and late observations of the optical counterpart of the very energetic GRB 130427A. Despite its moderate redshift z = 0.3399+/-0.0002, GRB 130427A is at the high end of the GRB energy distribution, with an isotropic-equivalent energy release of Eiso ~ 9.6x10^53 erg, more than an order of magnitude more energetic than other GRBs with spectroscopically confirmed SNe. In our dense photometric monitoring, we detect excess flux in the host-subtracted r-band light curve, consistent with what expected from an emerging SN, ~0.2 mag fainter than the prototypical SN 1998bw. A spectrum obtained around the time of the SN peak (16.7 days after the GRB) reveals broad undulations typical of SNe Ic-BL, confirming the presence of a SN, designated SN 2013cq. The spectral shape and early peak time are similar to those of the high expansion velocity SN 2010bh associated with GRB 100316D. Our findings demonstrate that high-energy long-duration GRBs, commonly detected at high redshift, can also be associated with SNe Ic-BL, pointing to a common progenitor mechanism.Comment: 12 pages, 4 figures, 1 table, accepted for publication in Ap

SSDSS IV MaNGA - Properties of AGN host galaxies

We present here the characterization of the main properties of a sample of 98 AGN host galaxies, both type-II and type-I, in comparison with those of about 2700 non-active galaxies observed by the MaNGA survey. We found that AGN hosts are morphologically early-type or early-spirals. For a given morphology AGN hosts are, in average, more massive, more compact, more central peaked and rather pressurethan rotational-supported systems. We confirm previous results indicating that AGN hosts are located in the intermediate/transition region between star-forming and non-star-forming galaxies (i.e., the so-called green valley), both in the ColorMagnitude and the star formation main sequence diagrams. Taking into account their relative distribution in terms of the stellar metallicity and oxygen gas abundance and a rough estimation of their molecular gas content, we consider that these galaxies are in the process of halting/quenching the star formation, in an actual transition between both groups. The analysis of the radial distributions of the starformation rate, specific star-formation rate, and molecular gas density shows that the quenching happens from inside-out involving both a decrease of the efficiency of the star formation and a deficit of molecular gas. All the intermediate data-products used to derive the results of our analysis are distributed in a database including the spatial distribution and average properties of the stellar populations and ionized gas, published as a Sloan Digital Sky Survey Value Added Catalog being part of the 14th Data Release: http://www.sdss.org/dr14/manga/manga-data/manga-pipe3d-value-added-catalog/Comment: 48 pages, 14 figures, in press in RMxA