113 research outputs found

    Insights into the catalytic production of hydrogen from propane in the presence of oxygen: cooperative presence of vanadium and gold catalysts

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    [EN] H-2 and propylene can be obtained from propane and oxygen in defect using appropriate catalysts. Meanwhile propylene is formed from propane via oxidative or non-oxidative dehydrogenation, molecular hydrogen can be obtained from several reactions such as propane dehydrogenation, coke formation and water gas shift. It has been observed that a gold catalyst hardly activates propane and no H-2 was detected, whereas using vanadium oxide a relatively high concentration of propylene and H-2 was obtained. Interestingly, the simultaneous use of vanadium oxide and gold has meant a higher hydrogen production, higher in a 40% than that of the catalyst containing only vanadium oxide. This performance has been. related to the capacity of gold to activate CO in the water gas shift reaction. (C) 2015 Elsevier B.V. All rights reserved.The authors would like to acknowledge the DGICYT in Spain (CTQ2012-37925-C03-1, CTQ2012-37925-C03-2 and CTQ2012-37984-C02-01) for financial support We also thank the University of Valencia and SCSIE-UV for assistance. J.M. Lopez would also like to thank Spanish MICINN and CSIC for funding his Ramon y Cajal contract (RYC-2009-04483).Garcia, T.; Lopez, JM.; López Nieto, JM.; Sanchis, R.; Dejoz, A.; Vazquez, MI.; Solsona, B. (2015). Insights into the catalytic production of hydrogen from propane in the presence of oxygen: cooperative presence of vanadium and gold catalysts. Fuel Processing Technology. 134:290-296. https://doi.org/10.1016/j.fuproc.2015.02.012S29029613

    Catalytic behavior of NaV6O15 bronze for partial oxidation of hydrogen sulfide

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    [EN] Na-containing V2O5 materials have been prepared hydrothermally from gels with Na/V ratios of 0.02-0.26, and calcined at 500 degrees C. The calcined samples have been characterized and tested as catalysts in the partial oxidation of H2S to elemental sulfur. At low Na-contents, V2O5 and NaV6O15 bronze are formed, with the NaV6O15/V2O5 ratio increasing with the Na-content. Pure NaV6O15 bronze is mainly formed from gels containing a Na/V ratio of 0.18. However, NaV6O15 and Na1.164V3O8 are formed from gels with Na/V ratio higher than 0.35. NaV6O15 based catalyst shows high conversion for the oxidation of H2S with a high selectivity into elemental sulfur. These catalysts are more active and stable than pure or Na-doped V2O5 catalysts. V4O9 is observed after reaction in both pure Na-doped V2O5 catalysts but also in NaV6O15/V2O5 mixed catalysts. However, no changes in the NaV6O15 crystalline structure are observed in the Na-promoted catalysts. Accordingly, NaV6O15 crystalline phase is stable for several hours of catalysisat a difference with V2O5. The active sites in V-containing vanadium catalysts are probably V5+-O-V4+ pairs as previously proposed for V4O9 crystalline phase. The best catalytic performances were achieved on V2O5-NaV6O15 mixtures which are transformed into V4O9-NaV6O15 mixtures during the catalytic tests. These catalytic results could be due to the intrinsic physical properties of both phases but also because of the optimal dispersion obtained in the synthesis procedure. (C) 2014 Elsevier B.V. All rights reserved.The authors would like to thank the DGICYT in Spain (Projects CTQ2012-37925-C03-01, CTQ2012-37925-C03-03 and MAT2010-19837-C06-05) for financial support.Soriano Rodríguez, MD.; Rodriguez-Castellon, E.; Garcia-Gonzalez, E.; López Nieto, JM. (2014). Catalytic behavior of NaV6O15 bronze for partial oxidation of hydrogen sulfide. Catalysis Today. 238:62-68. https://doi.org/10.1016/j.cattod.2014.02.030S626823

    Wind-induced changes in the dynamics of fluorescent organic matter in the coastal NW Mediterranean

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    Original research paperMarine biogeochemistry dynamics in coastal marine areas is strongly influenced by episodic events such as rain, intense winds, river discharges and anthropogenic activities. We evaluated in this study the importance of these forcing events on modulating seasonal changes in the marine biogeochemistry of the northwestern coast of the Mediterranean Sea, based on data gathered from a fixed coastal sampling station in the area. A 4-year (2011–2014) monthly sampling at four depths (0.5 m, 20 m, 50 m and 80 m) was performed to examine the time variability of several oceanographic variables: seawater temperature, salinity, inorganic nutrient concentrations (NO3−, PO43 − and SiO2), chlorophyll a (Chl a), dissolved organic carbon (DOC) and fluorescent dissolved organic matter (FDOM). FDOM dynamics was predominantly influenced by upwelling events and mixing processes, driven by strong and characteristic wind episodes. SW wind episodes favored the upwelling of deeper and denser waters into the shallower shelf, providing a surplus of autochthonous humic-like material and inorganic nutrients, whereas northerlies favored the homogenization of the whole shelf water column by cooling and evaporation. These different wind-induced processes (deep water intrusion or mixing), reported along the four sampled years, determined a high interannual environmental variability in comparison with other Mediterranean sampling sites. Graphical abstract Image 1 Download : Download high-res image (344KB)Download : Download full-size imageECOSER (CTM2011-15937-E), DOREMI (CTM2012-342949), SUAVE (CTM2014/ 23456/1) and ANIMA (CTM2015-65720) from the Spanish Ministerio de Economía y Competitividad (MINECO) and the Grup de Recerca Consolidat 2014SGR1179 and 2014SGR1029 financed by the Agència de Gestió d'Ajuts Universitaris i de Recerca (AGAUR) from the Generalitat de Catalunya; (JAEPre_2011_00923) from the Agencia Estatal Consejo Su perior de Investigaciones Científicas (CSIC) and the project FERMIO (MINECO, CTM2014-57334-JIN) co-financed with FEDER fundsVersión del editor3,25

    Preparation, characterization and catalytic behavior for propanepartial oxidation of Ga-promoted MoVTeO catalysts

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    [EN] Two sets of Ga-promoted MoVTeO catalysts were synthesized hydrothermally and heat-treated at 600 degrees C in N-2: (i) materials prepared from gels with Mo/V/Te/Ga atomic ratios of 1/0.60/0.17/x (x=0-0.12) (A-series) and (ii) materials prepared from gels with Mo/V/Te/Ga atomic ratios of 1/0.60-x/0.17/x (x=0.15 or 0.25) (B-series). In addition, a Ga-containing MoVTeO catalyst was also prepared from M1-containing MoVTeO material by impregnation with aqueous solution of gallium and heat-treated at 450 degrees C in N-2. Catalysts were characterized by means of powder XRD, TEM, Raman spectroscopy, NH3-TPD and XPS and tested in the partial oxidation of propane. The results showed that the addition of small amount of gallium significantly increase the selectivity to acrylic acid (AA) at low propane conversion. However, at high propane conversion, the selectivity to AA strongly depends on both the catalyst composition and the gallium incorporation method. The higher selectivity to acrylic acid over Ga-containing MoVTeO catalysts has been related to: (i) structural changes in the M1 phase by the incorporation of Ga3+ into the octahedral structural framework and/or (ii) incorporation of Ga3+ species on the catalyst surface thus modifying catalysts acid properties. (C) 2014 Elsevier B.V. All rights reserved.Financial support from DGICYT in Spain (Project CTQ2012-37925-C03-1 and Program Severo Ochoa SEV-2012-0267) is gratefully acknowledged. EGG acknowledges finantial support through spanish project MAT2010-19837-C06-05 and the ICTS-Microscopia Electronica in Madrid for facilities.Hernández Morejudo, S.; Massó Ramírez, A.; García-González, E.; Concepción Heydorn, P.; López Nieto, JM. (2015). Preparation, characterization and catalytic behavior for propanepartial oxidation of Ga-promoted MoVTeO catalysts. Applied Catalysis A: General. 504:51-61. https://doi.org/10.1016/j.apcata.2014.12.039S516150

    Determinants and Differences in Satisfaction with the Inhaler Among Patients with Asthma or COPD

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    Satisfaction with the inhaler is an important determinant of treatment adherence in patients with asthma and chronic obstructive pulmonary disease (COPD). However, few studies have compared these 2 groups to identify the factors associated with satisfaction with the inhaler. To assess and compare satisfaction with the inhaler in patients with asthma or COPD and to determine the variables associated with high inhaler satisfaction. A multicenter, cross-sectional study of 816 patients (406 with asthma and 410 with COPD) was conducted. Satisfaction was assessed with the Feeling of Satisfaction with Inhaler (FSI-10) questionnaire. All participants completed the Test of Adherence to Inhalers and either the Asthma Control Test (ACT) or the COPD Assessment Test (CAT). Overall, the asthma group was significantly more satisfied with the inhaler (mean [standard deviation] FSI-10 scores: 44.1 [6.5] vs 42.0 [7.7]; P <.001) and more satisfied on most (7 of 10; 70%) items. Patients with asthma were significantly more satisfied with the inhaler regardless of the adherence level or the type of nonadherence pattern. Younger age, good disease control (ACT ≥20 or CAT ≤10), previous inhaler training, and absence of unwitting nonadherence were all independently and significantly associated with high inhaler satisfaction. Age, disease control, and training in inhalation technique all play a more significant role than the specific diagnosis in explaining satisfaction with the device in patients with asthma and COPD. These findings underscore the need to provide better training and more active monitoring of the inhalation technique to improve patient satisfaction, treatment adherence, and clinical outcomes

    Vanadium oxide supported on porous clay heterostructure for the partial oxidation of hydrogen sulphide to sulfur

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    Vanadium oxide supported on porous clay heterostructures (PCH) catalysts have been synthesized, characterized and evaluated in the selective oxidation of H2S to elemental sulfur. The catalysts were characterized by XRD, adsorption-desorption of N-2 at -196 degrees C, diffuse reflectance UV-vis, H-2-TPR, Raman spectroscopy and XPS. The catalysts with higher vanadium content are more active and selective, exhibiting a H2S conversion close to 70% after 360h on stream with a high selectivity toward elemental sulfur and a low formation of undesired SO2. The catalysts with V2O5 crystallites have shown a higher activity and resistance to the deactivation. The analysis of the spent catalyst has revealed the formation of V4O9 crystals during the catalytic test, which has been reported as the active phase in the selective oxidation of the H2S. (C) 2015 Elsevier B.V. All rights reserved.The authors would like to thank the DGICYT in Spain (Projects CTQ2012-37925-C03-01, CTQ2012-37925-C03-03 and FEDER funds, and MAT2010-19837-C06-05) and project of Excellence of Junta de Andalucia (project P12-RNM-1565) for financial support. A. Natoli thanks to SECAT (Spain) for a grant.Soriano Rodríguez, MD.; Cecilia, JA.; Natoli, A.; Jimenez-Jimenez, J.; López Nieto, JM.; Rodriguez Castellon, E. (2015). Vanadium oxide supported on porous clay heterostructure for the partial oxidation of hydrogen sulphide to sulfur. Catalysis Today. 254:36-42. https://doi.org/10.1016/j.cattod.2014.12.022S364225

    Unfolding of differential energy spectra in the MAGIC experiment

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    The paper describes the different methods, used in the MAGIC experiment, to unfold experimental energy distributions of cosmic ray particles (gamma-rays). Questions and problems related to the unfolding are discussed. Various procedures are proposed which can help to make the unfolding robust and reliable. The different methods and procedures are implemented in the MAGIC software and are used in most of the analyses.Comment: Submitted to NIM

    Implementation of the Random Forest Method for the Imaging Atmospheric Cherenkov Telescope MAGIC

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    The paper describes an application of the tree classification method Random Forest (RF), as used in the analysis of data from the ground-based gamma telescope MAGIC. In such telescopes, cosmic gamma-rays are observed and have to be discriminated against a dominating background of hadronic cosmic-ray particles. We describe the application of RF for this gamma/hadron separation. The RF method often shows superior performance in comparison with traditional semi-empirical techniques. Critical issues of the method and its implementation are discussed. An application of the RF method for estimation of a continuous parameter from related variables, rather than discrete classes, is also discussed.Comment: 16 pages, 8 figure

    Efficacy and safety of preoperative preparation with Lugol''s iodine solution in euthyroid patients with Graves’ disease (LIGRADIS Trial): Study protocol for a multicenter randomized trial

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    Background: Currently, both the American Thyroid Association and the European Thyroid Association recommend preoperative preparation with Lugol''s Solution (LS) for patients undergoing thyroidectomy for Graves’ Disease (GD), but their recommendations are based on low-quality evidence. The LIGRADIS trial aims to provide evidence either to support or refute the systematic use of LS in euthyroid patients undergoing thyroidectomy for GD. Methods: A multicenter randomized controlled trial will be performed. Patients =18 years of age, diagnosed with GD, treated with antithyroid drugs, euthyroid and proposed for total thyroidectomy will be eligible for inclusion. Exclusion criteria will be prior thyroid or parathyroid surgery, hyperparathyroidism that requires associated parathyroidectomy, thyroid cancer that requires adding a lymph node dissection, iodine allergy, consumption of lithium or amiodarone, medically unfit patients (ASA-IV), breastfeeding women, preoperative vocal cord palsy and planned endoscopic, video-assisted or remote access surgery. Between January 2020 and January 2022, 270 patients will be randomized for either receiving or not preoperative preparation with LS. Researchers will be blinded to treatment assignment. The primary outcome will be the rate of postoperative complications: hypoparathyroidism, recurrent laryngeal nerve injury, hematoma, surgical site infection or death. Secondary outcomes will be intraoperative events (Thyroidectomy Difficulty Scale score, blood loss, recurrent laryngeal nerve neuromonitoring signal loss), operative time, postoperative length of stay, hospital readmissions, permanent complications and adverse events associated to LS. Conclusions: There is no conclusive evidence supporting the benefits of preoperative treatment with LS in this setting. This trial aims to provide new insights into future Clinical Practice Guidelines recommendations. Trial registration: ClinicalTrials.gov identifier: NCT03980132. © 202
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