398 research outputs found

    Formation of secondary organic aerosols from the ozonolysis of dihydrofurans

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    In this work we report the study of the ozonolysis of 2,5-dihydrofuran and 2,3-dihydrofuran and the reaction conditions leading to the formation of secondary organic aerosols. The reactions have been carried out in a Teflon chamber filled with synthetic air mixtures at atmospheric pressure and room temperature. The ozonolysis only produced particles in the presence of SO2. Rising relative humidity from 0 to 40% had no effect on the production of secondary organic aerosol in the case of 2,5-dihydrofuran, while it reduced the particle number and particle mass concentrations from the 2,3-dihydrofuran ozonolysis. The water-to-SO2 rate constant ratio for the 2,3-dihydrofuran Criegee intermediate was derived from the secondary organic aerosol (SOA) yields in experiments with different relative humidity values, kH2O/kSO2 = (9.8 ± 3.7) × 10-5. The experimental results show that SO3 may not be the only intermediate involved in the formation or growth of new particles in contrast to the data reported for other Criegee intermediate-SO2 reactions. For the studied reactions, SO2 concentrations remained constant during the experiments, behaving as a catalyst in the production of condensable products. Computational calculations also show that the stabilised Criegee intermediates from the ozonolysis reaction of both 2,5-dihydrofuran and 2,3-dihydrofuran may react with SO2, resulting in the regeneration of SO2 and the formation of low-volatility organic acids.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

    Acotaciones a la visión orsiana de los fundamentos jurídicos del sistema económico capitalista

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    D’Ors no escribió muchas páginas sobre economía, pero tenía ideas muy claras al respecto. Entendía que el derecho era autónomo con respecto a la economía, o más bien que ésta debería estar condicionada por él. Los autores consideran que su oposición al sistema capitalista es una de las consecuencias de abordar la economía desde una perspectiva jurídica, aunque no cabe negar la razonabilidad de sus argumentos. Hay dos puntos básicamente, que le suscitan problemas: la percepción de un interés por el préstamo de dinero y la confusión entre préstamo y propiedad en el caso de las sociedades anónimas.D'Ors did not write many pages about economics but had very clear ideas about it. He understood that law was autonomous with respect to economy, or rather that economy should be conditioned by law. The authors consider that his opposition to the capitalist system is one of the consequences of approaching the economy from a legal perspective although it should not be ignored the reasonableness of d’Ors arguments. There are basically two issues that are problematics for him: the perception of an interest in the loan of money and the confusion between loan and property in the case of corporations

    The Non-thermal Radio Jet Toward the NGC 2264 Star Formation Region

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    We report sensitive VLA 3.6 cm radio observations toward the head of the Cone nebula in NGC 2264, made in 2006. The purpose of these observations was to study a non-thermal radio jet recently discovered, that appears to emanate from the head of the Cone nebula. The jet is highly polarized, with well-defined knots, and one-sided. The comparison of our images with 1995 archive data indicates no evidence of proper motions nor polarization changes. We find reliable flux density variations in only one knot, which we tentatively identify as the core of a quasar or radio galaxy. An extragalactic location seems to be the best explanation for this jet.Comment: 12 pages, 5 figure

    Manual de técnicas de estabilización biotécnica en taludes de infraestructuras de obra civil

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    Formation of secondary organic aerosols from the ozonolysis of dihydrofurans

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    In this work we report the study of the ozonolysis of 2,5-dihydrofuran and 2,3-dihydrofuran and the reaction conditions leading to the formation of secondary organic aerosols. The reactions have been carried out in a Teflon chamber filled with synthetic air mixtures at atmospheric pressure and room temperature. The ozonolysis only produced particles in the presence of SO2. Rising relative humidity from 0 to 40% had no effect on the production of secondary organic aerosol in the case of 2,5-dihydrofuran, while it reduced the particle number and particle mass concentrations from the 2,3-dihydrofuran ozonolysis. The water-to-SO2 rate constant ratio for the 2,3-dihydrofuran Criegee intermediate was derived from the secondary organic aerosol (SOA) yields in experiments with different relative humidity values, kH2O/kSO2 = (9.8 ± 3.7) × 10-5. The experimental results show that SO3 may not be the only intermediate involved in the formation or growth of new particles in contrast to the data reported for other Criegee intermediate-SO2 reactions. For the studied reactions, SO2 concentrations remained constant during the experiments, behaving as a catalyst in the production of condensable products. Computational calculations also show that the stabilised Criegee intermediates from the ozonolysis reaction of both 2,5-dihydrofuran and 2,3-dihydrofuran may react with SO2, resulting in the regeneration of SO2 and the formation of low-volatility organic acids.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

    Pressure-Driven Isostructural Phase Transition in InNbO4: In Situ Experimental and Theoretical Investigations

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    "This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/page/policy/articlesonrequest/index.html"[EN] The high-pressure behavior of technologically important visible-light photocatalytic semiconductor In.NbO4, adopting a monoclinic wolframite-type structure at ambient conditions, was investigated using synchrotron-based X-ray diffraction, Raman spectroscopic measurements, and first-principles calculations. The experimental results indicate the occurrence of a pressure-induced isostructural phase transition in the studied compound beyond 10.8 GPa. The large volume collapse associated with the phase transition and the coexistence of two phases observed over a wide range of pressure shows the nature of transition to be first-order. There is an increase in the oxygen anion coordination number around In and Nb cations from six to eight at the phase transition. The ambient-pressure phase has been recovered on pressure release. The experimental pressure volume data when fitted to a Birch-Murnaghan equation of states yields the value of ambient pressure bulk modulus as 179(2) and 231(4) GPa for the low and high-pressure phases, respectively. The pressure dependence of the Raman mode frequencies and Gruneisen parameters was determined for both phases by experimental and theoretical methods. The same information is obtained for the infrared modes from first-principles calculations. Results from theoretical calculations corroborate the experimental findings. They also provide information on the compressibility of interatomic bonds, which is correlated with the macroscopic properties of InNbO4.This research was supported by the Spanish Ministerio de Economia y Competitividad (MINECO), the Spanish Research Agency (AEI), and the European Fund for Regional Development (FEDER) under Grant Nos. MAT2013-46649-004-01/02/03-P, MAT2016-75586-C4-1/2/3-P, and MAT2015-71070-REDC (MALTA Consolider). J.A.S. acknowledges financial support through the Ramon y Cajal Fellowship.Garg, AB.; Errandonea, D.; Popescu, C.; Martínez-García, D.; Pellicer Porres, J.; Rodríguez-Hernández, P.; Muñoz, A.... (2017). Pressure-Driven Isostructural Phase Transition in InNbO4: In Situ Experimental and Theoretical Investigations. Inorganic Chemistry. 56(9):5420-5430. https://doi.org/10.1021/acs.inorgchem.7b00437S5420543056

    Calidad de la leche cruda para consumo humano en dos localidades de Sucre (Colombia)

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    Objective. To determine the physicochemical, microbiological and somatic cell count of raw milks marketed for human consumption in neighborhoods of Sincelejo and Corozal (Sucre). Materials and methods. A cross-sectional study was carried out in 97 samples of raw milk marketed for human consumption in different neighborhoods of Sincelejo and Corozal (Sucre). Physical-chemical, microbiological and somatic cell count parameters were determined. The data obtained were analyzed according to the regulations in normative measures in Colombia. Results. Most of the physical-chemical parameters of the raw milk samples analyzed were found within the normal range according to Colombian legislation. Mesophilic count and somatic cells count was found to be above what is allowed by the legislation. The presence of total and fecal coliforms, antibiotics and adulterants such as sucrose and starches were determined. Conclusions. Raw milks distributed for human consumption in Sincelejo and Corozal presents good physical-chemical quality but poor microbiological quality; it becomes necessary to increase surveillance and to demand the production of excellent quality milk in the primary sector in the dairy chain.Objetivo. Determinar la calidad fisicoquímica, microbiológica y recuento de células somáticas de leches crudas que se distribuyen para consumo humano en diferentes barrios de Sincelejo y Corozal (Sucre). Materiales y métodos. Mediante un estudio descriptivo de corte transversal, se tomaron 97 muestras de leche cruda; se determinaron algunos parámetros fisicoquímicos, microbiológicos y recuento de células somáticas. Los datos obtenidos se analizaron de acuerdo a la normatividad vigente en Colombia. Resultados. La mayoría de los parámetros fisicoquímicos de las muestras de leche cruda evaluadas se encontraron dentro de los parámetros normales de la legislación colombina. El recuento estándar en placa y el recuento de células somáticas se encontraron por encima de lo permitido por la legislación. Se demostró la presencia de coliformes totales, coliformes fecales, antibióticos y adulterantes como sacarosa y almidones. Conclusiones. La leche cruda que se distribuye para consumo humano en  Sincelejo y Corozal presenta  buena calidad fisicoquímica pero deficiente calidad microbiológica; se hace necesario incrementar la vigilancia y exigir al eslabón primario de la cadena láctea la producción de leche de excelente calidad

    High-Pressure Properties of Wolframite-Type ScNbO4

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    In this work, we used Raman spectroscopic and optical absorption measurements and first-principles calculations to unravel the properties of wolframite-type ScNbO4 at ambient pressure and under high pressure. We found that monoclinic wolframite-type ScNbO4 is less compressible than most wolframites and that under high pressure it undergoes two phase transitions at ∼5 and ∼11 GPa, respectively. The first transition induces a 9% collapse of volume and a 1.5 eV decrease of the band gap energy, changing the direct band gap to an indirect one. According to calculations, pressure induces symmetry changes (P2/c–Pnna–P2/c). The structural sequence is validated by the agreement between phonon calculations and Raman experiments and between band structure calculations and optical absorption experiments. We also obtained the pressure dependence of Raman modes and proposed a mode assignment based upon calculations. They also provided information on infrared modes and elastic constants. Finally, noncovalent and charge analyses were employed to analyze the bonding evolution of ScNbO4 under pressure. They show that the bonding nature of ScNbO4 does not change significantly under pressure. In particular, the ionicity of the wolframite phase is 61% and changes to 63.5% at the phase transition taking place at ∼5 GPa

    Effect of β-Glucans in Diets on Growth, Survival, Digestive Enzyme Activity, and Immune System and Intestinal Barrier Gene Expression for Tropical Gar (Atractosteus tropicus) Juveniles

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    The application of β-1,3/1,6-glucan derived from yeast at five concentrations (0%, 0.5%, 1.0%, 1.5%, and 2.0%) in formulated diets was evaluated in juveniles for its effects on the growth, survival, digestive enzymatic activity, and expression of genes associated with the immune system (interlukin-10 (IL-10), transforming growth factor (TGF), occludin (OCC), mucin2 (MUC2), lysozyme (LYS), and nucleotide-binding and oligomerization domain 2 (NOD2)) in tropical gar (Atractosteus tropicus). For the experiment, three replicates of 30 fish per experimental unit (70 L) were cultivated for 62 days. The growth results showed no statistically significant differences in relation to weight and total length between treatments. The activity of digestive enzymes (alkaline proteases, trypsin, leucine aminopeptidase, and amylase) did not show significant differences between treatments, except for chymotrypsin activity, where fish fed 1.0% and 1.5% of β-glucans showed higher activities compared with the rest of the treatments. On the other hand, the analysis of gene expression did not show significant differences between treatments, although a tendency of increase in the expression of IL-10, TGF, MUC2, and OCC was observed with an addition of 1.5% of the prebiotic, but there was a decrease in the fish fed with 2% of the prebiotic. It is possible to include concentrations of between 0.5% and 1.5% of β-glucans in the diets for A. tropicus, with no detectable adverse effects on growth, survival, digestive enzyme activity, or specific gene expression. β-glucan 1,3/1,6 added at 1.0% and 1.5% in the diet significantly increases chymotrypsin activity.info:eu-repo/semantics/publishedVersio

    Sex differences in treatment strategy for coronary artery aneurysms: Insights from the international Coronary Artery Aneurysm Registry

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    INTRODUCTION: Sex disparities exist in coronary artery disease (CAD) in terms of risk profile, clinical management and outcome. It is unclear if differences are also present in coronary aneurysms, a rare variant of CAD. METHODS: Patients were selected from the international Coronary Artery Aneurysm Registry (CAAR; ClinicalTrials.gov: NCT02563626), and differences between groups were analysed according to sex. The CAAR database is a prospective multicentre registry of 1565 patients with coronary aneurysms (336 females). Kaplan-Meier method was used for event-free survival analysis for death, major adverse cardiac events (MACE: composite endpoint of death, heart failure and acute coronary syndrome) and bleeding. RESULTS: Female patients were older, were more often hypertensive and less frequently smoker. They were treated conservatively more often compared to male patients and received significantly less frequently aspirin (92% vs 88%, p = 0.002) or dual antiplatelet therapy (DAPT) (67% vs 58%, p = 0.001) at discharge. Median DAPT duration was also shorter (3 vs 9 months, p = 0.001). Kaplan-Meier analysis revealed no sex differences in death, MACE or bleeding during a median follow-up duration of 37 months, although male patients did experience acute coronary syndrome (ACS) more often during follow-up (15% vs 10%, p = 0.015). CONCLUSIONS: These CAAR findings showed a comparable high-risk cardiovascular risk profile for both sexes. Female patients were treated conservatively more often and received DAPT less often at discharge, with a shorter DAPT duration. ACS was more prevalent among male patients; however, overall clinical outcome was not different between male and female patients during follow-up
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