Bronces de óxido de vanadio como catalizadores para la activación selectiva de enlaces C-H y S-H

[ES] En los últimos años, debido al aumento de la contaminación global y su impacto sobre el medio ambiente, se ha puesto especial énfasis en el desarrollo de nuevos procesos catalíticos respetuosos con el medioambiente. La síntesis de nuevos materiales, para su aplicación como catalizadores activos y selectivos en procesos de petroquímica y de eliminación de contaminantes, es uno de los campos de investigación más activo dentro del área de los procesos químicos. Entre los diferentes tipos de materiales, se ha puesto de manifiesto el interés en el desarrollo de catalizadores basados en óxidos mixtos no estequiométricos, empleados para reacciones de oxidación parcial de hidrocarburos y de derivados de la biomasa, o incluso para la eliminación de contaminantes. En la presente tesis doctoral se estudia, de forma comparativa, la síntesis y caracterización de bronces de óxidos de vanadio del tipo MxV2O5 (donde M = Na, Ag, Ca y Cu), en especial aquellos con estructura β-MxV2O5 (β-Na0,33V2O5, β-Ag0,333V2O5, β-Ca0,17V2O5 y β´-Cu0,261V2O5), y su empleo como catalizadores para la oxidación parcial de sulfuro de hidrógeno a azufre elemental y para la oxidación parcial de etanol y metanol. En primer lugar, se prepararon los catalizadores por el método hidrotermal y fueron caracterizados mediante el empleo de diferentes técnicas físico-químicas: adsorción de N2, DRX, TPR-H2, microscopía electrónica de barrido (SEM), EDX y las espectroscopias Raman, FTIR y XPS. Los resultados de la caracterización mostraron que las características estructurales y texturales de los materiales sintetizados dependen del precursor metálico y de la relación M/V empleada en el gel de síntesis. Pero, además, ambos factores afectan de forma diferente dependiendo del metal y del bronce de óxido de vanadio estudiado. A continuación, se estudió el comportamiento catalítico de materiales basados en bronces de óxido de vanadio, tales como β-Na0,33V2O5, β-Ag0,333V2O5, β-Ca0,17V2O5 y β´-Cu0,261V2O5. Pero también, la influencia de la presencia de otras fases cristalinas (V2O5, vanadatos metálicos y otros tipos de bronces de vanadio MxV2O5) sobre la actividad catalítica y la selectividad para la reacción de oxidación parcial de sulfuro de hidrógeno. Los resultados que se exponen en la presente memoria, confirman que los bronces de óxido de vanadio con estructura monoclínica (β-Na0,33V2O5, β-Ag0,333V2O5, β-Ca0,17V2O5 y β´-Cu0,261V2O5) son activos y selectivos en la reacción de oxidación parcial de H2S a azufre. Además, la actividad aumenta con la reducibilidad del bronce debido no sólo a la presencia de pares V4+-O-V5+, sino también, a la influencia del metal incorporado (Mn+···V4+-O-V5+) que afecta de manera diferente a las propiedades redox de los átomos de vanadio. Por otra parte, la caracterización de los catalizadores después de reacción muestra que la estructura cristalina de dichos bronces es estable durante la reacción, mientras que la presencia de otras fases (V2O5 o vanadato) da lugar a una disminución de la actividad catalítica y de la estabilidad de dichos catalizadores. Finalmente, el estudio comparativo de la oxidación parcial de metanol y etanol sobre los bronces de óxido de vanadio (β-Na0,33V2O5, β-Ag0,333V2O5, β-Ca0,17V2O5 y β´-Cu0,261V2O5) confirman que estos materiales son también activos y selectivos a la formación del correspondiente aldehído, si bien el comportamiento catalítico (cuando comparamos la selectividad a altas conversiones de alcohol) depende no sólo de la habilidad redox de los átomos de vanadio (y la posible velocidad de reoxidación del catalizador durante la reacción), sino también de las características ácidas de estos materiales, impurezas de Na+ y Ca2+, y reactividad del alcohol. Del estudio de la transformación aeróbica de ambos alcoholes se desprende que la actividad catalítica para la conversión de etanol es mayor que para la conversión de metanol. Además, en general, la selectividad a formaldehído (a partir de metanol) o acetaldehído (a partir de etanol) es similar entre ellos, y también similar al V2O5. Esto podría estar relacionado con la influencia del estado de oxidación de los átomos de vanadio en los catalizadores durante la reacción, lo que podría ser consecuencia de pequeños cambios con respecto a lo observado para la reacción de oxidación de H2S. También se discuten las diferencias en el mecanismo de reacción para la transformación de ambas moléculas.[EN] In last years, the increase in global pollution and its negative impact on the environment has led to the development of new environmentally friendly catalytic processes. The synthesis of new materials, for application as active and selective catalysts in petrochemical and pollutant removal processes, it is one of the most active fields of research in the area of chemical processes. There is special interest in the development of catalysts based on non-stoichiometric mixed, used for partial oxidation reactions of hydrocarbons and biomass derivatives, or even for the removal of contaminants. The present doctoral thesis presents a study, in a comparative way, on the synthesis and characterization of MxV2O5 vanadium oxide bronzes (for M=Na, Ag, Ca y Cu), specifically catalysts with structure ß-MxV2O5 (ß-Na0,33V2O5, ß-Ag0,333V2O5, ß-Ca0,17V2O5 and ß-Cu0,261V2O5), and its use as catalyst in the partial oxidation of hydrogen sulphide to sulphur and partial oxidation of ethanol and methanol. Firstly, it was prepared the catalysts by hydrothermal method and the physic-chemical characterizations of catalysts have been determined by using: adsorption of N2, DRX, TPR-H2, scanning electron microscope (SEM), EDX, Raman spectroscopy, FTIR and XPS. The results of characterization showed that the structural and textural properties of the synthesized materials depend on the metal precursor and the M/V ratio used in the synthesis gel. But, in addition, both factors affect differently depending on the type of metal and the vanadium oxide bronze studied. In a second step, the catalytic behaviour of materials based on vanadium oxide bronzes, such as ß-MxV2O5, were studied. Also, it has been studied the influence of the presence other crystalline phases (V2O5, metal vanadate and other vanadium bronzes MxV2O5) on the catalytic performance of these catalysts for the partial oxidation of H2S to sulphur. The results have allowed us to confirm that the vanadium oxide bronzes (ß-MxV2O5) are active and selective in the partial oxidation of H2S to sulphur. In addition, the catalytic activity increases with the catalyst reducibility, due not only to the presence of V4+-O-V5+ pairs in these bronzes, but also to the influence of the incorporated metal (Mn+···V4+-O-V5+) that differently affects the redox properties of vanadium atoms. On the other hand, the characterization of the catalysts after reaction shows that the ß-MxV2O5 crystalline structure is stable during the partial oxidation of H2S, while catalysts presenting other crystalline phases (V2O5 or vanadate) decrease both the catalytic activity and the stability of some catalysts. Finally, a comparative study of the partial oxidation of methanol and ethanol (to formaldehyde and acetaldehyde, respectively) on vanadium oxide bronzes (ß-MxV2O5) have confirmed that these materials are active and selective to the formation of the corresponding aldehyde. However, their catalytic behaviour (especially when comparing selectivity at high alcohol conversion) strongly depends not only on the redox ability of vanadium atoms (and the possible rate of catalyst reoxidation during the reaction), but also of the acidic characteristics of these materials, impurities of Na+ or Ca2+, and the reactivity of alcohols. The study of the aerobic transformation of both alcohols shows that the catalytic activity for the conversion of ethanol is greater than for the conversion of methanol. In addition, in general, similar results to formaldehyde (from methanol) or acetaldehyde (from ethanol) have been observed, presenting also selectivity to aldehyde similar to pure V2O5. This could be related to influences on the oxidation states of vanadium atoms in the catalysts during the reaction, which could be as a consequence of small changes with respect to observed during the H2S oxidation. Also, it was discussed the differences in the mechanism of reaction for the transformation of both methanol and ethanol.[CA] Als últims anys, a causa de l’augment de la contaminació global i l’impacte sobre el medi ambient, s’ha posat especial èmfasi en el desenvolupament de nous processos catalítics respectuosos amb el medi ambient. La síntesi de nous materials, per a la seua aplicació com a catalitzadors actius i selectius en processos de petroquímica i d’eliminació de contaminants, el qual és un dels camps d’ investigació més actiu de l’àrea dels processos químics. I, entre els diferents tipus de materials, s’ha posat de manifest l’interès en el desenvolupament de catalitzadors basats en òxids mixtes no estequiomètrics, empleats per reaccions d’oxidació parcial d´hidrocarburs i de derivats de la biomassa, o fins i tot per l’eliminació de contaminants. En la present tesi doctoral s’estudia, de forma comparativa, la síntesi i caracterització de bronzes d’òxid de vanadi del tipus MxV2O5 (on M = Na, Ag, Ca y Cu), en especial aquells amb estructura β-MxV2O5 (β-Na0,33V2O5, β-Ag0,333V2O5, β-Ca0,17V2O5 y β´-Cu0,261V2O5), i la seua utilització com a catalitzadors per a l’oxidació parcial de sulfurs d’hidrogen a sofre elemental i per a l’oxidació parcial d’etanol i metanol. En primer lloc, es van preparar els catalitzadors pel mètode hidrotermal i van ser caracteritzats per la utilització de tècniques fisicoquímiques: adsorció de N2 (SBET), DRX, TPR-H2, microscòpia de barrejada (SEM), EDX i les espectroscòpies Raman, FTIR i XPS. Els resultats de la caracterització mostraren que les característiques estructurals i texturals dels materials sintetitzats depenen del precursor metàl·lic i de la relació M/V empleada en el gel de síntesi. Però a més a més, tots dos factors afecten de forma diferent depenent del tipus de metall i del bronze de òxid de vanadi estudiat. A continuació, es va estudiar el comportament catalític de materials basats en bronzes d’òxid de vanadi, tals com β-Na0,33V2O5, β-Ag0,333V2O5, β-Ca0,17V2O5 y β´-Cu0,261V2O5. Però, també l’influencia de la presencia d’impureses d’altres fases cristal·lines (com el V2O5, vanadats metàl·lics i altres tipus de bronzes de vanadi xV2O5) sobre l’activitat catalítica i la selectivitat per a la reacció d’oxidació parcial de sulfur d’hidrogen a sofre elemental. Els resultats que s’exposen en la present memòria, confirmen que els bronzes d’òxid de vanadi en estructura monoclínica (β-Na0,33V2O5, β-Ag0,333V2O5, β-Ca0,17V2O5 y β´-Cu0,261V2O5)són actius i selectius en la reacció d’oxidació parcial de H2S. I, a mes a més, l’activitat augmenta en la reductibilitat del bronze degut no sols a la presència de pars V4+-O-V5+ en aquests bronzes, sinó també la influència del metall incorporat (Mn+···V4+-O-V5+) que afecta de manera diferent les propietats redox dels àtoms de vanadi. Per altra banda, la caracterització dels catalitzadors després de la reacció, mostra que l’estructura cristal·lina d’aquests bronzes és estable durant la reacció, mentrestant la presència d’altres fases (V2O5 o vanadat) dona lloc a la disminució de l’activitat catalítica i de l’estabilitat de aquests catalitzadors. Finalment, l’estudi comparatiu de l’oxidació parcial de metanol i etanol sobre els bronzes de òxid de vanadi (β-Na0,33V2O5, β-Ag0,333V2O5, β-Ca0,17V2O5 y β´-Cu0,261V2O5) confirmen que aquests materials són també actius i selectius a la formació del corresponent aldehid, si bé el comportament catalític (quan comparem la selectivitat a altes conversions d’alcohol) depén no sols de l’habilitat redox dels àtoms de vanadi (i la possible velocitat de re-oxidació del catalitzador durant la reacció), sinó també de les característiques àcides d’aquests materials, impureses de Na+ i Ca2+, ireactivitat de l´alcohol. De l’estudi de la transformació aeròbica d’ambdós alcohols es desprén que l’activitat catalítica per a la conversió d’etanol és major que per a la conversió de metanol. Aleshores, en general, la selectivitat a formaldehid (a partir de metanol) o la selectivitat a acetaldehid (a partir d’etanol) és similar entre ells, i també similar al V2O5. Això podria estar relacionat amb la influència de l´estat d´oxidació dels àtoms de vanadi en els catalitzadors durant la reacció, el que podria ser conseqüència de xicotets canvis respecte a allò observat per a la reacció d’oxidació de H2S. També es discuteix les diferències als mecanismes de reacció per a la transformació d’ambdues molècules.Ruiz Rodríguez, L. (2020). Bronces de óxido de vanadio como catalizadores para la activación selectiva de enlaces C-H y S-H [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/149488TESI

Dehiscencia anastomótica tras cirugía por enfermedad diverticular del colon: estudio comparativo

Introducción: La enfermedad diverticular del colon (EDC) es muy frecuente en nuestro medio. De modo preferente, afecta al colon sigmoide. La mayoría de los pacientes se controlan con tratamiento conservador, pero en los que precisan intervención quirúrgica, la colectomía sigmoidea es uno de los principales tratamientos y la dehiscencia anastomótica (DA) una de las complicaciones más importantes y temidas. En la literatura existen resultados contradictorios entre los diferentes factores de riesgo (FR) relacionados con el desarrollo de esta. Objetivo: Estudiar si existen diferencias en una serie de variables clínicas y/o quirúrgicas entre los pacientes que desarrollan una dehiscencia anastomótica y aquellos que no, tras ser tratados de enfermedad diverticular de colon con resección del colon y reconstrucción del tránsito digestivo. Material y métodos: Se trata de un estudio clínico retrospectivo, observacional y analítico. Los datos se obtuvieron de los pacientes intervenidos por EDC en el Servicio de Cirugía General del Hospital Universitario de San Juan de Alicante (HUSJA) con resección y anastomosis de colon en el periodo comprendido de septiembre de 2016 a diciembre de 2022. Se dividió a los pacientes en dos grupos, por un lado, los que desarrollaron DA tras la intervención, y por el otro lado, los que no, comparando entre ellos diferentes variables demográficas, clínicas y quirúrgicas. Resultados: La muestra fue de un total de 68 pacientes intervenidos por EDC con resección y anastomosis, en el tiempo estudiado. A partir de la información derivada del total de la muestra obtenemos que la mediana de edad fue de 58 años, con una mayoría de pacientes varones (58,8%), la comorbilidad más prevalente fue el consumo de tabaco (32,4%), el 94,1 % de los pacientes fueron intervenidos de manera electiva, empleando en el 92,6% de las ocasiones como abordaje quirúrgico la laparotomía, y el principal tipo de anastomosis empleada fue manual (72%). Presentaron DA 13 pacientes lo que representa un 19,1% de la muestra. La mediana del día postoperatorio que aparece la DA es a los 13 días, en su mayoría se trataron y solucionaron con terapia conservadora. En estos pacientes se prolongó la estancia hospitalaria, con una mediana de duración de 16 días. Se encontraron diferencias estadísticamente significativas cuando se comparó al grupo de DA y no DA en una serie de variables, tales como: transfusiones perioperatorias (p=0.003), niveles de PCR en el tercer día postoperatorio (p<0.01), complicaciones postoperatorias de tipo no DA (p=0,035) y en la duración de la hospitalización (p=0.013). Por otra parte, no encontramos diferencias en otras variables tales como vía de abordaje quirúrgica, tipo de intervención o la variable relacionada con el cirujano, entre otras. Conclusiones: Se encontraron diferencias estadísticamente significativas en los pacientes que desarrollaron DA, para las variablestransfusiones perioperatorias, niveles de PCR al tercer día postoperatorio, complicaciones postoperatorias de tipo no DA y duración de la hospitalizaciónIntroduction: Diverticular disease of the colon (DDC) is very common in our environment. Preferably, it affects the sigmoid colon. Most patients are treated with conservative treatment, but in those who require surgical intervention, sigmoid colectomy is one of the main treatments and anastomotic dehiscence (AD) is one of the most important and feared complications. There are conflicting results in the literature regarding the different risk factors (RF) related to the development of AD. Objective: To study whether there are differences in a series of clinical and/or surgical variables between patients who develop anastomotic dehiscence and those who do not, after being treated for diverticular disease of the colon with colon resection and reconstruction of the digestive tract. Materials and methods: This is a retrospective, observational, and analytical clinical study. The data were obtained from patients operated on for DDC in the General Surgery Department of the University Hospital of San Juan de Alicante (HUSJA) with colon resection and anastomosis from September 2016 to December 2022. The patients were divided into two groups: those who developed AD after the intervention, and those who did not, comparing different demographic, clinical, and surgical variables between them. Results: The sample consisted of a total of 68 patients who underwent EDC with resection and anastomosis during the study period. Based on the information derived from the total sample, we found that the median age was 58 years, with most male patients (58.8%). The most prevalent comorbidity was tobacco use (32.4%), 94.1% of the patients underwent elective surgery, and laparotomy was used as the surgical approach in 92.6% of cases, with manual anastomosis being the main type used (72%). Thirteen patients (19.1% of the sample) presented with anastomotic dehiscence (AD). The median postoperative day on which AD occurred was 13 days, and the majority were treated and resolved with conservative therapy. These patients had a prolonged hospital stay, with a median duration of 16 days. Statistically significant differences were found when comparing the AD and non-AD groups in several variables, such as perioperative transfusions (p=0.003), PCR levels on the third postoperative day (p<0.01), non-AD postoperative complications (p=0.035), and hospitalization duration (p=0.013). On the other hand, no differences were found in other variables such as surgical approach, type of intervention, or surgeon-related variables, among others. Conclusions: Statistically significant differences were found in patients who developed AD for the variables of perioperative transfusions, PCR levels on the third postoperative day, non-AD postoperative complications, and hospitalization duration

Partial oxidation of H2S to sulfur on V-Cu-O mixed oxides bronzes

[EN] The present paper shows the influence of Cu-content in Cu-promoted V2O5 catalysts on both the physicochemical characteristics of catalysts and their catalytic performance in the partial oxidation of hydrogen sulfide. Both, the catalytic activity for H2S conversion and the selectivity to sulfur increased when increasing the Cu/V ratio of catalysts. The best catalyst gives a selectivity to sulfur at ca. 98% at total conversion of H2S. According to the characterization results (XRD, FTIR), V2O5 is partially transformed into vanadium oxide bronze, i.e. beta-Cu0.261V2O5, up to Cu/V ratios of 0.25. For higher Cu/V ratios, CuV2O6 and beta-Cu0.261V2O5 are observed. In the same way, the reducibility of V-species increased when increasing the Cu/V ratio of catalysts. On the other hand, the characterization of used catalysts indicates the transformation of V2O5 into V4O9, whereas the vanadium oxide bronze is stable under the studied reaction. The catalytic results are explained on the basis of the nature of crystalline phases and the presence of V5+-O-V4+ pairs in the more selective catalysts.The authors would like to acknowledge the Spanish MINECO Projects (CTQ2015-68951-C3-1-R and CTQ2015-68951-C3-3-R) and Severo Ochoa Program (SEV-2016-0683), and FEDER funds, for financial support. LRR thanks the MINECO for a predoctoral contract.Ruiz-Rodríguez, L.; Blasco Lanzuela, T.; López Nieto, JM.; Rodríguez-Castellón, E. (2019). Partial oxidation of H2S to sulfur on V-Cu-O mixed oxides bronzes. Catalysis Today. 333:237-244. https://doi.org/10.1016/j.cattod.2018.07.050S23724433

Correlation Between Endoglin and Malignant Phenotype in Human Melanoma Cells: Analysis of hsa-mir-214 and hsa-mir-370 in Cells and Their Extracellular Vesicles.

Endoglin (CD105) is an auxiliary receptor of transforming growth factor (TGF)-β family members that is expressed in human melanomas. It is heterogeneously expressed by primary and metastatic melanoma cells, and endoglin targeting as a therapeutic strategy for melanoma tumors is currently been explored. However, its involvement in tumor development and malignancy is not fully understood. Here, we find that endoglin expression correlates with malignancy of primary melanomas and cultured melanoma cell lines. Next, we have analyzed the effect of ectopic endoglin expression on two miRNAs (hsa-mir-214 and hsa-mir-370), both involved in melanoma tumor progression and endoglin regulation. We show that compared with control cells, overexpression of endoglin in the WM-164 melanoma cell line induces; (i) a significant increase of hsa-mir-214 levels in small extracellular vesicles (EVs) as well as an increased trend in cells; and (ii) significantly lower levels of hsa-mir-370 in the EVs fractions, whereas no significant differences were found in cells. As hsa-mir-214 and hsa-mir-370 are not just involved in melanoma tumor progression, but they can also target endoglin-expressing endothelial cells in the tumor vasculature, these results suggest a complex and differential regulatory mechanism involving the intracellular and extracellular signaling of hsa-mir-214 and hsa-mir-370 in melanoma development and progression.S

The role of promoters on the catalytic performance of MxV2O5 bronzes for the selective partial oxidation of H2S

[EN] Metal-containing vanadium oxide bronzes (MxV2O5; M= Cu, Ag and Ca) have been prepared, characterized (before and after reaction) by various physicochemical techniques, and tested in the partial oxidation of H2S. The catalysts were prepared hydrothermally at 175 ¿C (from gels containing M/V molar ratios of 0.17 or 0.33) and heat-treated at 500 ¿C/2 h in N2. The most effective catalysts, showing a sulfur selectivity greater than 95 % for a H2S conversion beyond 90 %, were those presenting vanadium oxide bronze (ß-Cu0.261V2O5 or Ag0.333V2O5) as the main crystalline phase. Cu- and Ag-containing vanadium oxide bronzes were stable under reaction conditions. For calcium containing materials (mainly presenting the Ca0.17V2O5 bronze phase), the formation of CaSO4 has been observed during the reaction, which resulted in a negative effect on both activity and selectivity. The nature of active and selective sites in this type of catalysts, as well as the role of promoters, are also discussed.The authors would like to acknowledge the Ministerio de Ciencia e Innovacion of Spain (TED2021-130756B-C31, TED2021-130756B-C32 and MAT2017-84118-C2-1-R projects) . Authors from ITQ also thank Project SEV-2016-0683 for supporting this research. A.A. acknowledges Severo Ochoa Excellence Program for his fellowship (BES-2017-080329) and Dr. Ferran Sabate from ITQ for his assistance with the EPR data treatment.Ruiz-Rodríguez, L.; De Arriba-Mateos, A.; Vidal Moya, JA.; Blasco Lanzuela, T.; Rodríguez-Castellón, E.; López Nieto, JM. (2022). The role of promoters on the catalytic performance of MxV2O5 bronzes for the selective partial oxidation of H2S. Applied Catalysis A General. 647:1-11. https://doi.org/10.1016/j.apcata.2022.11890011164

Endoglin Protein Interactome Profiling Identifies TRIM21 and Galectin-3 as New Binding Partners

This article belongs to the Special Issue TGF-beta/BMP Signaling PathwayEndoglin is a 180-kDa glycoprotein receptor primarily expressed by the vascular endothelium and involved in cardiovascular disease and cancer. Heterozygous mutations in the endoglin gene (ENG) cause hereditary hemorrhagic telangiectasia type 1, a vascular disease that presents with nasal and gastrointestinal bleeding, skin and mucosa telangiectases, and arteriovenous malformations in internal organs. A circulating form of endoglin (alias soluble endoglin, sEng), proteolytically released from the membrane-bound protein, has been observed in several inflammation-related pathological conditions and appears to contribute to endothelial dysfunction and cancer development through unknown mechanisms. Membrane-bound endoglin is an auxiliary component of the TGF-ß receptor complex and the extracellular region of endoglin has been shown to interact with types I and II TGF-ß receptors, as well as with BMP9 and BMP10 ligands, both members of the TGF-ß family. To search for novel protein interactors, we screened a microarray containing over 9000 unique human proteins using recombinant sEng as bait. We find that sEng binds with high affinity, at least, to 22 new proteins. Among these, we validated the interaction of endoglin with galectin-3, a secreted member of the lectin family with capacity to bind membrane glycoproteins, and with tripartite motif-containing protein 21 (TRIM21), an E3 ubiquitin-protein ligase. Using human endothelial cells and Chinese hamster ovary cells, we showed that endoglin co-immunoprecipitates and co-localizes with galectin-3 or TRIM21. These results open new research avenues on endoglin function and regulation.This work was supported by grants from Ministerio de Ciencia, Innovación y Universidades of Spain (SAF2013-43421-R to CB and SAF2017-84183-R to MQ), Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER; ISCIII-CB06/07/0038 to CB and contract CNV-234-PRF-360 to LR-L) and Consejo Superior de Investigaciones Científicas (CSIC; 201920E022 to CB). JC-V was supported by a postdoctoral contract co-funded by Consejo Superior de Investigaciones Científicas, Ministerio de Ciencia, Innovación y Universidades and the European Social Fund (ESF). CIBERER and CIBERNED are initiatives of the Instituto de Salud Carlos III (ISCIII) of Spain supported by European Regional Development (FEDER) funds

Geodiversity, Geoconservation, and Geotourism in Central America

Abstract: Central America is located in a dynamic region where tectonics and volcanism together with the tropical climate and its diverse vegetation have shaped the landscapes. Our main objective is to review the status of the geodiversity, geoconservation, and geotourism in Central America. We will identify the region’s geomorphic environments and geodiversity using classic regional geomorphology mapping techniques. Likewise, using touristic maps and webpages, we identify the most prominent geosites of different origin in Central America. Moreover, we will explore the national environmental policies, natural conservation systems, and tourism initiatives to promote their national geoheritage through geotourism. We found that volcanic, coastal, karstic, glacial, and fluvial geomorphic environments are the most common in the region. In addition, we identified 393 geosites of volcanic, coastal, karstic, glacial, fluvial, and archeological origin in Central America. The promotion of geoheritage, geodiversity, geoconservation, and thus the development of geoparks are excellent opportunities to promote sustainable development, sustainable lifestyles, appreciation of natural and cultural diversity, and the promotion of peace. These results may prove important to spread information about geoscience widely to decision makers on geotourism and conservation in each country and the stakeholders of the region. Geoheritage studies in tropical and developing countries such as those in Central America should be improved, and priority should be given to the geomorphological dynamics and strong anthropic pressures on their geo- and biodiversity to increase their income through geotourism, especially among the less favored communities and avoid affecting their already threatened natural resources.UCR::Vicerrectoría de Docencia::Ciencias Sociales::Facultad de Ciencias Sociales::Escuela de Geografí

Percepción del estrés en los estudiantes de Enfermería ante sus prácticas clínicas

Objective: This research aims to establish what the Nursing students’ main stress sources are during their practice period, according to their gender, grade and age. Methodology. It is a descriptive transversal study. The sample was composed by 45 Nursing students, 30 women and 15 men, at the University of Murcia in 2010/2011. The information gathering tool was KEZKAK questionnaire. Results. The ignorance facing a determined clinical situation and the risk of damaging the patient are the Nursing students’ two main stress sources. Men often suffer from a bigger stress than women; nevertheless, as well as the age increases and the students pass grades, the stress level is smaller. Conclusions. Nursing students’ stress determines their formation within their clinical practices period. Thus, it is necessary that the theoretical learning that supports these practices considers theses needs that own Nursing students require.OBJETIVO. Esta investigación pretende conocer cuáles son las principales fuentes de estrés durante el periodo de prácticas de los estudiantes de Enfermería de la Universidad de Murcia en función de su sexo, curso y edad. METODOLOGÍA. Se trata de un estudio transversal de corte descriptiva. La muestra estuvo compuesta por un total de 45 alumnos, 30 mujeres y 15 hombres, de Enfermería de la Universidad de Murcia del curso académico 2010/2011. El instrumento de recogida de la información fue cuestionario KEKZAK. RESULTADOS. El desconocimiento ante una determinada situación clínica y el riesgo de dañar al paciente son las dos principales fuentes estresoras para los estudiantes de enfermería. Los hombres suelen sufrir un mayor estrés que sus compañeras; no obstante, a medida que aumenta la edad y se avanza de curso el grado de estrés es cada vez menor. CONCLUSIONES. El estrés de los estudiantes de enfermería marca su formación durante el período de prácticas clínicas. Por tanto, se hace necesario que el aprendizaje teórico que sustenta a las prácticas atienda a estas necesidades que los propios estudiantes de enfermería demandan

V- and Nb-containing tungsten bronzes catalysts for the aerobic transformation of ethanol and glycerol. Bulk and supported materials

[EN] This work report the applicability of reflux to the synthesis of supported tungsten bronzes (i.e. W-V-O and W-Nb-O), using mesoporous KIT-6 as inert support. For comparison, the corresponding bulk materials prepared by reflux or by hydrothermal synthesis have been also prepared. The catalysts were characterized by several techniques (X-ray diffraction, N-2 adsorption, temperature programmed desorption (NH3), and Raman and FTIR spectroscopies) and tested in the selective aerobic transformation of ethanol and glycerol. These results demonstrate the formation of V- and Nb-containing tungsten oxide bronzes in all of the heat-treated samples (bulk and supported materials), as well as the effective incorporation of metals (V or Nb) in the framework of tungsten bronzes. During the aerobic transformation of ethanol, diethyl ether and ethylene (in Nb-containing catalysts) and acetaldehyde, diethyl ether and ethylene (in V-containing catalysts) were the main reaction products, with very small formation of carbon oxides. During the aerobic transformation of glycerol, acrolein was mainly formed over Nb-containing catalysts, whereas acrylic acid, acrolein and COx were mainly observed over V-containing catalysts. The differences between bulk and supported catalysts have been explained according to changes in their physico-chemical properties: V-containing catalysts presenting both acid and redox sites; and Nb-containing catalysts presenting acid sites. In this way, supported materials seems to be effective in both redox and acid reactions due to the small modifications of the acid characteristics of catalysts.The authors would like to acknowledge the DGICYT (CTQ2015-68951-C3-1-R) and Secretary of State for International Cooperation in Spain (Project AP/040992/11). N.S and D.D thank "Conselho Nacional de Desenvolvimento Cientifico y Tecnologico (CNPq)" in Brasil and Severo Ochoa Excellence Program (SVP-2014-068669) in Spain, respectively, for their fellowships. Authors are also grateful to the Electron Microscopy Service (Universitat Politecnica de Valencia) for facilities.La Salvia, N.; Delgado-Muñoz, D.; Ruiz-Rodríguez, L.; Nadji, L.; Massó Ramírez, A.; López Nieto, JM. (2017). V- and Nb-containing tungsten bronzes catalysts for the aerobic transformation of ethanol and glycerol. Bulk and supported materials. Catalysis Today. 296:2-9. https://doi.org/10.1016/j.cattod.2017.04.009S2929