316 research outputs found

    γ-Al2O3 as acid catalyst for dehydration of glucose to 5-hydroxymethylfurfural

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    Currently, the search and development of sustainable feedstocks for chemicals derived from petrol have gained worldwide attraction because of the instability of the price of crude oil, the reduction of fossil oil reserves, and the environmental concerns associated to the greenhouse effect caused by CO2 emissions, being biomass one of the world’s most important renewable carbon sources. The major component of plant-derived biomass are carbohydrates, being of great importance to develop efficient and green approaches to their valorization by conversion into high value-added products. Thus, glucose can be transformed by dehydration into 5-hydroxymethylfurfural (HMF), which is a versatile and key intermediate for the production of a wide variety of biobased chemicals and it is attracting much attention in biofuels and chemical industry. Different catalytic systems have been evaluated for HMF production from C6 carbohydrates as glucose, mostly based on heterogeneous catalysis as alternative to the use of liquid mineral acids. On the other hand, the high surface area, large pore size and thermal and hydrothermal stabilities of some mesoporous solids make them suitable for many catalytic processes. In the present work, the dehydration of glucose to HMF has been evaluated by using different mesoporous γ-Al2O3 with acid, neutral or basic character, in a biphasic water–MIBK solvent system to avoid the HMF degradation and its possible reaction with the intermediates from glucose to give soluble polymers and humins or acetalization with glucose. Different experimental parameters, such as reaction temperature and time, as well as the addition of inorganic salts have been studied in order to reach the maximum HMF yield.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Ministry of Economy and Competitiveness (CTQ2012-38204-C04-02 project), Junta de Andalucía (RNM-1565) and FEDER fund

    Mesoporous niobium oxide for dehydration of D-xylose into furfural

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    Se ha demostrado que el óxido de niobio mesoporoso es un catalizador eficaz para la deshidratación de D-xilosa a furfural, alcanzando una conversión del 92% y un rendimiento de furfural 49,3% a 170º C y 90 minutos. La lixiviación de Nb, determinada por ICP-MS, era inferior al 0,5% en peso de la concentración de Nb inicial, confirmando de este modo la estabilidad del catalizador ácido sólido.El furfural posee un gran potencial como molécula plataforma de origen renovable para la síntesis de una alta variedad de compuestos químicos. Se obtiene mediante la deshidratación de pentosas, principalmente a partir de D-xilosa, proceso catalizado por ácidos minerales en fase homogénea. Por tanto, dentro de la química verde y la búsqueda de sostenibilidad de los procesos catalíticos, es necesaria su sustitución por catalizadores sólidos ácidos que sean tolerantes al agua, ya que es el disolvente más utilizado para esta reacción. El óxido de niobio posee propiedades ácidas y es insoluble en agua, pero su superficie específica es muy baja. Por lo tanto, resulta muy interesante la síntesis de un óxido de niobio mesoporoso para emplearlo como catalizador en esta reacción. En este trabajo, se ha sintetizado un Nb2O5 mesoporoso y se ha evaluado su comportamiento catalítico en la obtención de furfural a partir de D-xilosa.Spanish Ministry of Science and Innovation (ENE2009-12743-C04-03 project)Junta de Andalucía (P09-FQM-5070).Ministry of Science and Innovation for the financial support under the Program Ramón y Cajal (RYC-2008-03387)

    Granulobasidium vellereum (Ellis &Cragin) Jülich, a promising biological control agent

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    Studies involving biological control of wood decay fungi and pests in forest areas are scarce. The basidiomycete Granulobasidium vellereum (Ellis & Cragin) Jülich has been isolated as wood endophyte from London Plane trees (Platanus acerifolia (Ait.) Willd). This basidiomycete produces a variety of sesquiterpenes with antifungal activity. In this study we evaluated the potential activity of G. vellereum against wood decay fungi and fungi associated with the ambrosia beetle Megaplatypus mutatus Chapuis, an important forest pest in Populus sp. A combination of in vitro assays was made, in cultures and on wood blocks. Granulobasidium vellereum’s Volatile Organic Compounds (FVOCs) were characterized and their potential role in biocontrol was assessed. Granulobasidium vellereum did not cause a significant loss of weight on P. acerifolia and Populus wood and inhibited the growth of the target fungi, mainly when inoculated first. Up to nineteen volatile compounds were determined in G. vellereum strains. The growth of all target fungi was inhibited by FVOCs and in some cases the morphology of the fungi was altered. These results indicate that G. vellereum can be used as a Biological Control Agent (BCA) of xylophagous fungi and fungi related to forest pests. Further investigations should focus on developing application strategies for M. mutatus management.Fil: Robles, Carolina Analía. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Ceriani Nakamurakare, Esteban Daniel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Micología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Slodowicz, Mariel Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; ArgentinaFil: Gonzalez Audino, Paola Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; ArgentinaFil: Carmaran, Cecilia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; Argentin

    Altered pituitary morphology as a sign of benign hereditary chorea caused by TITF1/NKX2.1 mutations

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    Benign hereditary chorea (BHC) is a rare genetically heterogeneous movement disorder, in which conventional neuroimaging has been reported as normal in most cases. Cystic pituitary abnormalities and features of empty sella have been described in only 7 patients with BHC to date. We present 4 patients from 2 families with a BHC phenotype, 3 of whom underwent targeted pituitary MR imaging and genetic testing. All four patients in the two families displayed a classic BHC phenotype. The targeted pituitary MR imaging demonstrated abnormal pituitary sella morphology. Genetic testing was performed in three patients, and showed mutations causing BHC in three of the patients, as well as identifying a novel nonsense mutation of the TITF1/NKX2-1 gene in one of the patients. The presence of the abnormal pituitary sella in two affected members of the same family supports the hypothesis that this sign is a distinct feature of the BHC phenotype spectrum due to mutations in the TITF1 gene. Interestingly, these abnormalities seem to develop in adult life and are progressive. They occur in at least 26% of patients affected with Brain-lung-thyroid syndrome. As a part of the management of these patients we recommend to perform follow-up MRI brain with dedicated pituitary imaging also in adult life as the abnormality can occur years after the onset of chorea

    A Drug Combination Rescues Frataxin-Dependent Neural and Cardiac Pathophysiology in FA Models

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    Friedreich's ataxia (FA) is an inherited multisystemic neuro- and cardio-degenerative disorder. Seventy-four clinical trials are listed for FA (including past and present), but none are considered FDA/EMA-approved therapy. To date, FA therapeutic strategies have focused along two main lines using a single-drug approach: a) increasing frataxin and b) enhancing downstream pathways, including antioxidant levels and mitochondrial function. Our novel strategy employed a combinatorial approach to screen approved compounds to determine if a combination of molecules provided an additive or synergistic benefit to FA cells and/or animal models. Eight single drug molecules were administered to FA fibroblast patient cells: nicotinamide riboside, hemin, betamethasone, resveratrol, epicatechin, histone deacetylase inhibitor 109, methylene blue, and dimethyl fumarate. We measured their individual ability to induce FXN transcription and mitochondrial biogenesis in patient cells. Single-drug testing highlighted that dimethyl fumarate and resveratrol increased these two parameters. In addition, the simultaneous administration of these two drugs was the most effective in terms of FXN mRNA and mitobiogenesis increase. Interestingly, this combination also improved mitochondrial functions and reduced reactive oxygen species in neurons and cardiomyocytes. Behavioral tests in an FA mouse model treated with dimethyl fumarate and resveratrol demonstrated improved rotarod performance. Our data suggest that dimethyl fumarate is effective as a single agent, and the addition of resveratrol provides further benefit in some assays without showing toxicity. Therefore, they could be a valuable combination to counteract FA pathophysiology. Further studies will help fully understand the potential of a combined therapeutic strategy in FA pathophysiology

    Influence of synthesis conditions in the catalytic performance of Nb-P catalysts

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    Glycerol is a natural byproduct of the manufacture of soaps from the hydrolysis of animal fats and vegetable oils. Due to the incessant increment of the worldwide production of biodiesel, the production of glycerol, a by-product of the biodiesel industry, has notably increased causing as consequence a drop in its price. In this way, glycerol has been turned into an interesting starting raw material for others chemical products, where the double dehydration of glycerol to acrolein is one of proposed routes for glycerol valorisation. Because of the crude glycerine is found diluted in water, the catalysts must be active and resistance to the presence of water avoiding a separation step of the glycerine from the water and therefore reducing the price of production of acrolein. Various solid acid catalysts have been tested in the dehydration of glycerol, including nio-bium oxide [1-3], phosphoric acid [4, 5] and zirconium niobium mixed oxides [6]. These catalysts reach the full conversion of glycerol and acrolein selectivities as high as 75mol% [3]. However, the main drawback of these cata-lysts is the deactivation with time on stream due to mainly to adsorption of high boiling point compounds. The characteristic features of the catalysts affecting to the catalytic activity are related to the amount of acid centers and the type of acid sites. The catalytic activity is related to Nb – OH groups and polymeric structures exposing Nb=O species [3, 6]. The main goal of this work is to evaluated how the preparation of the catalysts affect to the catalytic activity of supported niobia-phosporous on a mesoporous silica SBA-15 doped with zirconium. Doping with zirconium improves the acidity of the support and the stability of the catalysts as it has been shown previously [7]. 2 Experimental For the synthesis of mesoporous silica SBA-15 doped with zirconium (Si/Zr molar ratio of 5), 8 g of EO20-PO70-EO20 (Pluronic 123 from Aldrich) polymer was dissolved in 288 mL of a 1.7 M HCl aqueous solution and stirred at 313 K for 1 day. Then, 14.6 mL of tetraethoxysilane and 5.8 mL of zirconium n-propoxide were added, under vigorous stirring. The resulting solution was aged at room temperature for 3 days. The final product was fil-tered, washed with water and dried at 333 K. The solid was calcined at 823 K for 6 h. The support was labelled as SiZr This solid was impregnated with niobium oxalate to achieve a 8wt% of Nb2O5 by using the incipient wetness impregnation. The catalyst was dried and calcined at 673 K during 4h (heating rate 2 K/min) and labelled SiZr_8Nb2O5. The niobium-phosphorous catalysts were prepared following to two different strategies. In the first one, the support was impregnated with a solution of niobium oxalate (8wt%Nb2O5) and then dried over night at 333 K. Following, the phosphorous was added by using H3PO4 (85wt%) wiith Nb/P molar ratio of 0.2. Finally, the catalyst was dried and calcined at different temperatures (523, 673 and 973 K) during 4 hours. The catalysts were labelled 0.2NbP-x where x is the temperature of calcination. In the second strategy, the support was impregnated with a solution containing niobium oxale and phosphoric acid with the Nb/P molar ratio of 0.2. This catalyst was calcined at 673 K for 4 hours and labelled 0.2NbP-400-I. The support and catalysts were characterized by means of nitrogen adsorption, elemental analysis, XDR, XPS, TPD-NH3 and adsorption of pyridine coupled to FTIR. The dehydration of glycerol was performed, at atmospheric pressure, in a fixed-bed continuous-flow stainless steel reactor (9.1mm in diameter, and 230mm in length), operated in the down-flow mode Catalysts were pre-treated in situ at atmospheric pressure under a nitrogen flow of 30 mLmin−1 at 598 K for 30 min. The glycerol solu-tion (10 wt.% in water) was supplied by means of HPLC pump at 0.05 mLmin−1 feed rate in a N2 flow (30mLmin−1). The evolution of catalytic tests was studied by collecting liquid samples after 2, 5 and 8 h in a vial cooled in an isopropanol–liquid N2 trap. These vials were sealed for posterior analysis by gas chromatography. The products measured were acrolein, acetaldehyde, hydroxyacetone and allyl alcohol. 3 Results and discussion The support and catalysts were studied by XRD to confirm the presence of the mesoporous structure which was mantained after the impregnation and calcination of the active phases. Moreove, it was not detected neither niobium phase nor phosphate phaser at higher 2.The SiZr catalyst show a high glycerol conversion even higher than the SiZr_8Nb2O5 within the 8 hours of time on stream (TOS) although the selectivity of the SiZr_8Nb2O5 to-wards acrolein is higher (Table 1). This issue is related to higher Brönsted acid sites present in the SiZr_8Nb2O5 since the SiZr support only shows Lewis acid sites. When phosphorus is added to the SiZr_8Nb2O5 catalyst (Table 1), the catalytic performance is improved both in terms of glycerol conversion and acrolein selectivity. It is observed an increase of Brönsted acid sites, probably the presence of P – OH speccies and a decrease of Lewis acid sites compared to the SiZr_8Nb2O5 catalyst. This improvement is only shows when the catalyst is calcined at 673 K (Figure 1) higher and lower calcination temperatures had not beneficial effect on the catalytic activity. It was also compared the catalytic activity when the impregnation with phosphorous and niobium was carried out in one step (Figure 2). In this case, the catalytic performance is drastically improved since the acrolein yield is increased in a 20mol%. This fact point out the presence of an active phase, no detected by XRD analysis, formed by interaction of niobium and phosphorous. 4 Conclusions The catalytic performance of a Nb-P catalyst supported on a mesoporous silica SBA-15 doped with zirconium is ameliorated when the impregnation of the two active phases is carried out in one step reaching an acrolein yield of 46mol% and a glycerol conversion of 85mol%Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Spanish Ministry of Economy and Competitiveness CTQ2012-38204-C03-02 project), Junta de Andalucía RNM-1565) and FEDER funds

    NB2O5 soportado en SBA-15 para la deshidratación de glicerol a acroleína

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    En este trabajo se evalúa la actividad catalítica del óxido de niobio soportado sobre sílice mesoporosa con estructura SBA-15 en la deshidratación de glicerol para la obtención de acroleínaLa producción industrial de la acroleína se basa en la oxidación selectiva del propeno, de origen fósil, en presencia de catalizadores complejos de BiMoOx . Debido a la disminución de los recursos petroquímicos, los recursos renovables se están haciendo más competitivos. Entre ellos destaca el glicerol, subproducto de la industria de producción de biodiésel. El glicerol tiene más de 1500 aplicaciones directas en las industrias farmacéuticas, alimentarias o cosmética. Entre las posibles reacciones que se están explorando destaca la deshidratación del glicerol a acroleína; debido a que la glicerina cruda se encuentra diluida en agua, es necesaria la búsqueda de catalizadores sólidos ácidos que sean activos y resistentes a la presencia de agua, evitando así el paso de separación y disminuyendo el coste de producción de acroleína. Con este fin, se han ensayado diferentes catalizadores sólidos ácidos, entre los que se encuentra el Nb2O5.Ministerio de Ciencia e Innovación (Proyecto ENE2009-12743-C04-03), Fondos FEDER y a la Junta de Andalucía (P09-FQM-5070) RMT al Ministerio de Ciencia e Innovación por la financiación dentro del Programa Ramón y Cajal (RYC-2008-03387

    Capturing the Severity and Impairment Associated With Depression: The Overall Depression Severity and Impairment Scale (ODSIS) Validation in a Spanish Clinical Sample

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    Background: The Overall Depression Severity and Impairment Scale (ODSIS) is a self-report scale designed to evaluate the severity and functional impairment associated with depression. Objective: This study evaluated the psychometric properties of the online version of the ODSIS in Spanish outpatients with depression and anxiety disorders. Method: Patients with a main diagnosis of a depressive (n = 283) or anxiety disorder (n = 191) and a mean age of 38.15 (SD = 12.06) were evaluated with a clinical diagnostic interview and measures assessing depression, anxiety, positive and negative affect, and quality of life. Factorial structure, internal consistency, convergent, and discriminant validity and cutoff scores were analyzed. Results: Consistent with previous validations of the instrument, Confirmatory Factor Analysis showed a unidimensional factor structure. Furthermore, the results obtained supported the internal consistency and construct validity of the ODSIS scores. A score of 5 was found to meet the criteria used in this study for the optimal cutoff score. Conclusion: The results obtained in this study show that the Spanish version of the ODSIS delivered online is an adequate tool to assess the depression-related severity and impairment in a brief and easy fashion

    Intercomparison of stratospheric nitrogen dioxide columns retrieved from ground-based DOAS and FTIR and satellite DOAS instruments over the subtropical Izana station

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    A 13-year analysis (2000–2012) of the NO2_{2} vertical column densities derived from ground-based (GB) instruments and satellites has been carried out over the Izaña NDACC (Network for the Detection of the Atmospheric Composition Change) subtropical site. Ground-based DOAS (differential optical absorption spectroscopy) and FTIR (Fourier transform infrared spectroscopy) instruments are intercompared to test mutual consistency and then used for validation of stratospheric NO2_{2} from OMI (Ozone Monitoring Instrument) and SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY). The intercomparison has been carried out taking into account the various differences existing in instruments, namely temporal coincidence, collocation, sensitivity, field of view, etc. The paper highlights the importance of considering an “effective solar zenith angle” instead of the actual one when comparing direct-sun instruments with zenith sky ones for a proper photochemical correction. Results show that NO2_{2} vertical column densities mean relative difference between FTIR and DOAS instruments is 2.8±10.7% for a.m. data. Both instruments properly reproduce the NO2_{2} seasonal and the interannual variation. Mean relative difference of the stratospheric NO2_{2} derived from OMI and DOAS is -0.2±8.7% and from OMI and FTIR is -1.6±6.7 %. SCIAMACHY mean relative difference is of 3.7 11.7 and -5.7±11.0% for DOAS and FTIR, respectively. Note that the days used for the intercomparison are not the same for all the pairs of instruments since it depends on the availability of data. The discrepancies are found to be seasonally dependent with largest differences in winter and excellent agreement in the spring months (AMJ). A preliminary analysis of NO2_{2} trends has been carried out with the available data series. Results show increases in stratospheric NO NO2_{2} columns in all instruments but larger values in those that are GB than that expected by nitrous oxide oxidation. The possible reasons for the discrepancy between instruments and the positive trends are discussed in the text

    Towards a multi-arm multi-stage platform trial of disease modifying approaches in Parkinson's disease

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    An increase in the efficiency of clinical trial conduct has been successfully demonstrated in the oncology field, by the use of multi-arm, multi-stage trials allowing the evaluation of multiple therapeutic candidates simultaneously, and seamless recruitment to Phase 3 for those candidates passing an interim signal of efficacy. Replicating this complex innovative trial design in diseases such as Parkinson's disease is appealing but in addition to the challenges associated with any trial assessing a single potentially disease modifying intervention in PD, a multi-arm platform trial must also specifically consider the heterogeneous nature of PD, alongside the desire to potentially test multiple treatments with different mechanisms of action. In a multi-arm trial, there is a need to appropriately stratify treatment arms to ensure each are comparable with a shared placebo/standard of care arm, however in PD there may be a preference to enrich an arm with a subgroup of patients that may be most likely to respond to a specific treatment approach. The solution to this conundrum lies in having clearly defined criteria for inclusion in each treatment arm as well as an analysis plan that takes account of pre-defined subgroups of interest, alongside evaluating the impact of each treatment on the broader population of PD patients. Beyond this, there must be robust processes of treatment selection, and consensus derived measures to confirm target engagement and interim assessments of efficacy, as well as consideration of the infrastructure needed to support recruitment, and the long-term funding and sustainability of the platform. This has to incorporate the diverse priorities of clinicians, triallists, regulatory authorities and above all the views of people with Parkinson's disease
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