Effect of nitric acid modification of montmorillonite clay on synthesis of solketal from glycerol and acetone

[EN]The effect of acid modification of a natural montmorillonite clay (MM) by HNO3 on the catalytic properties of MM from Dash-Salakhlinsk (Kazakhstan) has been investigated in the synthesis of solketal from glycerol and acetone in solvent free and acetonitrile media. HNO3 concentration allowed to control the chemical composition, the surface acidity, the porous structure of the acid-activated MMs and their catalytic performance. The main reaction product was solketal with 86.6–98% selectivity. Conversion of glycerol depended on the Brønsted acidity. The most active sample, namely, MM activated with 0.5 mol/dm3 HNO3, showed good reusability for 3 catalyst cycle

Utilización de imagen termográfica en el diagnóstico de patologías caninas

La termografía es un método complementario de diagnóstico por imagen que se basa en que los cuerpos emiten y reflejan radiación infrarroja, y esta radiación es captada y cuantificada por la cámara termográfica que la convierte en imágenes digitales. Esta cámara presenta múltiples paletas de colores que permiten la interpretación de las variaciones de temperatura. Se ha ensayado la aplicación de esta técnica en dos casos clínicos en perros con patologías en piel, el primero de los cuales presentaba dermatitis costrosa por Hypoderma profunda en cara, cuello y relieves óseos como consecuencia de leishmaniosis. El segundo caso fue a la consulta del hospital veterinario con una masa en la región cervical. Mediante la termografía se pudo localizar y delimitar los contornos de las lesiones con precisión. En este trabajo se ha estudiado el potencial de la termografía como método de diagnóstico por imagen en la especie canina.Thermography is a complementary method of imaging diagnosis which is based on the infrared radiation that bodies emit and reflex; this radiation is received and quantified by the thermographic camera that turns them into digital images. This camera has a lot of colour palettes which allow us to understand the temperature changes. The application of this technique has been tested with two dog clinical cases, the 1st one was a dermatitis produced by deep pyoderma on face, neck and bones reliefs, all of these caused by leishmaniasis. The 2nd case came to the veterinary hospital presenting a mass located on the neck area. Thanks to thermography the injuries can be located and delimitated accurately. The potential of thermography for imaging diagnosis on canine species has been evaluated in this work

The dynamics of radial sap flux density reflects changes in stomatal conductance in response to soil and air water deficit

10 páginas.-- 7 figuras.-- 1 tabla.-- 53 referenciasWater scarcity in semiarid regions of Europe threatens the sustainability of fruit tree orchards unless irrigation water is optimized and scheduled in deficit irrigation strategies. Stomatal conductance (gs) is one of the best indicators of plant water stress, since it is placed in the crossroad between water and CO2 fluxes at the leaf level. Unfortunately, it is not possible to measure gs automatically and continuously, which reduces its potential for irrigation scheduling. In this work we examined the use of sap flux density (Js) in the outer rings of the sapwood of olive trees as a surrogate of gs. The working hypothesis was that as olive trees are well-coupled to atmosphere because of their small leaves, the ratio of Js to air vapor pressure deficit (D) should correlate well with the dynamics of gs in the canopy. It was also expected that current year, sun exposed leaves were mainly connected to the outer rings of the sapwood, and the oldest, shaded leaves to the inner rings. This was tested by measuring gs in new, sun-exposed leaves vs gs in old, shaded leaves. Both hypotheses were contrasted and our results confirmed that gs can be estimated from Js/D (R2 of the relationships were always higher than 0.8). A wide range of estimated gs values (0.350-0.025molm-2s-1) were derived from Js measurements in an olive orchard under three different irrigation regimes. Results were satisfactory and open the possibility of applying this method to estimate gs and use it either as a reliable water stress indicator or in transpiration and photosynthesis models applied to fruit tree orchards under a wide range of water stress conditions.This experiment was funded by the Spanish Ministry of Science and Innovation, research project AGL2009-11310/AGR and by the Consejería de Economía, Innovación, Ciencia y Empleo, Junta de Andalucía (research project AGR-6456). Dr. Hernandez-Santana benefited from a Juan de la Cierva postdoctoral research fellowship from the Spanish Ministry of Science and Innovation. Thanks are due to the owners of Internacional Olivarera, S.A.U. (Interoliva), for allowing us to make the experiments in the Sanabria orchard.Peer reviewe

Effect of structure and acidity of acid modified clay materials on synthesis of octahydro-2H-chromen-4-ol from vanillin and isopulegol

The Prins cyclization of (−)-isopulegol with vanillin to form octahydro-2H-chromen-4-ol was studied in the presence of natural layered aluminosilicates modified by 0.5 mol/dm3 HCl, such as montmorillonite, kaolin, and metakaolin obtained by the calcination of kaolin at 650 °C. According to infrared spectroscopy using pyridine as probe molecule, the amount and strength of Brønsted acid sites depend on the type of clay and decrease in the following order HCl-montmorillonite > HCl-kaolin > HCl-metakaolin. The difference in Brønsted acidity and textural properties of clays affected the reaction rate and the selectivity towards octahydro-2H-chromen-4-o

Fenton degradation of sulfanilamide in the presence of Al,Fe-pillared clay: Catalytic behavior and identification of the intermediates

[EN]Liquid phase catalytic degradation of sulfanilamide with H2O2 was carried out in the presence of Fe,Al/M-pillared clay (Fe,Al/M-MM, M = Na+, Ca2+ and Ba2+) as heterogeneous Fenton type catalyst. Fe,Al/M-MMs were prepared by swelling of layered aluminosilicate (90–95 wt.% montmorillonite) from a bed located in Mukhortala (Buryatia, Russia) in Na+, Ca2+ and Ba2+ forms by means of the exchange of these cations with bulky Fe,Al-polyoxocations prepared at Al/Fe = 10/1 and OH/(Al + Fe) = 2.0, and then calcinated at 500 °C. XRD method and chemical analysis demonstrated that the rate of crystalline swelling was dependent on the interlayer cations and decreased in the order: Fe,Al-/Na-MM > Fe,Al/Ca-MM > Fe,Al/Ba-MM. It was found that the catalytic properties of Fe,Al/M-MMs depended on the type of exchangeable cations. The effect of the H2O2/sulfanilamide molar ratio, the catalyst content, the reaction temperature and the reaction pH on the removal rate of sulfanilamide has been studied in the presence of Fe,Al/Na-MM. The catalyst can be applied for degradation of sulfanilamide with H2O2 for at least three successive cycles without loss of activity. HPLC analyses pointed out that the main degradation intermediate products were sulfanilic acid, benzenesulfonic acid, p-benzoquinone and aliphatic carboxylic acids

Synthesis of octahydro-2H-chromen-4-ol from vanillin and isopulegol over acid modified montmorillonite clays: Effect of acidity on the Prins cyclization

Two calcium-rich natural layered aluminosilicates containing 90–95 wt.% montmorillonite were chemically activated using 0.125–3.0 M HCl solutions. Structural and textural properties were characterized by X-ray diffraction, elemental analysis and N2-adsorption/desorption analyses. According to infrared spectroscopy using pyridine as probe molecule, the amount of Brønsted acid sites increased when increasing HCl concentration. The catalytic performance of these materials was investigated in the Prins cyclization of (−)-isopulegol with vanillin to form octahydro-2H-chromen-4-ol, carried out in toluene at 35 °C. It was found that the amount of Brønsted acid sites and the microporosity of the catalysts are key factors for the control of the reaction rate and the selectivity towards octahydro-2H-chromen-4-o

Multipactor Threshold Estimation Techniques Based on Circuit Models, Electromagnetic Fields and Particle Simulators

[EN] Multipactor has become a keylimiting factor of the final performance of satellite communication systems, due to the increase in power levels and/or operating frequency bands. As a result, the critical components of these systems must meet demanding multipactor specifications which should be considered during the design process. This paper describes the different techniques available to predict the multipactor threshold power for radio frequency (RF) and microwave passive hardware under continuous wave (CW) excitation, from cumbersome particle simulations to fast approximate methods based on circuit models. All these techniques have been described and compared together for the first time, including also a detailed description of the configuration issues of commercial particle simulators required to obtain accurate multipactor threshold predictions. The techniques are applied to both wideband and narrowband application examples. The predictions have been compared with measured thresholds of manufactured samples obtained with a novel multipactor test bed, thus allowing to highlight the advantages and limitations of each technique and particle simulator. From this paper, it will be possible to choose the most suitable procedure (and an appropriate simulator, if needed) to obtain multipactor threshold prediction of passive hardware.The work of Pablo González was supported by the FPU Fellowship of the Ministerio de Educación, Cultura y Deporte, Spanish Government, with Ref. FPU17/02901. This work was supported in part by the Ministerio de Ciencia e Innovación (MICIN, Spanish Government) under R&D Project PID2019-103982RB-C41 (funded by MICIN/AEI/10.13039/501100011033), and in part by the European Space Agency (ESA) under Project H2020-ESA-007 (funded by the European Union's Horizon 2020 Research and Innovation Program).González-Santatecla, P.; Alcaide, C.; Cervera, R.; Rodríguez, M.; Monerris, Ó.; Petit, J.; Rodríguez Pérez, AM.... (2022). Multipactor Threshold Estimation Techniques Based on Circuit Models, Electromagnetic Fields and Particle Simulators. IEEE Journal of Microwaves. 2(1):57-77. https://doi.org/10.1109/JMW.2021.313228457772

Deletion or inhibition of NOD1 favors plaque stability and attenuates atherothrombosis in advanced atherogenesis

Atherothrombosis, the main cause of acute coronary syndromes (ACS), is characterized by the rupture of the atherosclerotic plaque followed by the formation of thrombi. Fatal plaque rupture sites show large necrotic cores combined with high levels of inflammation and thin layers of collagen. Plaque necrosis due to the death of macrophages and smooth muscle cells (SMCs) remains critical in the process. To determine the contribution of the innate immunity receptor NOD1 to the stability of atherosclerotic plaque, Apoe-/- and Apoe-/- Nod1-/- atherosclerosis prone mice were placed on a high-fat diet for 16 weeks to assess post-mortem advanced atherosclerosis in the aortic sinus. The proliferation and apoptosis activity were analyzed, as well as the foam cell formation capacity in these lesions and in primary cultures of macrophages and vascular SMCs obtained from both groups of mice. Our results reinforce the preeminent role for NOD1 in human atherosclerosis. Advanced plaque analysis in the Apoe-/- atherosclerosis model suggests that NOD1 deficiency may decrease the risk of atherothrombosis by decreasing leukocyte infiltration and reducing macrophage apoptosis. Furthermore, Nod1-/- SMCs exhibit higher proliferation rates and decreased apoptotic activity, contributing to thicker fibrous caps with reduced content of pro-thrombotic collagen. These findings demonstrate a direct link between NOD1 and plaque vulnerability through effects on both macrophages and SMCs, suggesting promising insights for early detection of biomarkers for treating patients before ACS occurs.This work was supported by the Ministerio Economía, Industria y Competitividad/Agencia Estatal de Investigación (SAF2016-79490-R, RTI2018-094727-B-100, SAF2015-64767-R, SAF2016-75004-R, SAF2017-82436-R/RTC2017-6283-1, PID2019-108977RB-100), Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CB16/11/00405, CB16/11/00257, CB16/11/00222), Fundación Ramón Areces (CIUP18A3864), Consorcio de Investigación en Red de la Comunidad de Madrid, S2017/BMD-3686 and Fondo Europeo de Desarrollo Regional

A New Reference Sample for High-Frequency Multipactor Testing

[EN] Multipactor (MP) is a high-power effect severely limiting the performance of satellite communication links. A reference sample is normally used in the experimental setups for MP testing in order to verify its correct operation. However, the low gaps required for high frequencies jeopardize the manufacturability of the devices traditionally used for this purpose. A new reference sample, based on a stepped-impedance resonator (SIR), is proposed in this letter. The key design considerations are also outlined. A prototype operating between 17 and 18 GHz has been manufactured and tested, proving the novel structure allows higher gaps, and is, thus, suitable for higher frequency bands.This work was supported in part by the Ministerio de Ciencia e Innovacion (Spanish Government) under Research and Development Project PID2019-103982RB-C41, in part by the European Space Agency(ESA) through several research and development activities, and in part by the ESA-VSC European High Power RF and Space Materials Laboratories for contributing with its installations through the European Regional Development Fund. The work of Pablo Gonzalez was supported by the FPU Fellowship ofthe Ministerio de Educacion, Cultura y Deporte under Grant FPU17/02901.González-Santatecla, P.; Smacchia, D.; Alcaide-Guillén, C.; Soto Pacheco, P.; Rodríguez Pérez, AM.; Morro, JV.; Mata-Sanz, R.... (2023). A New Reference Sample for High-Frequency Multipactor Testing. IEEE Microwave and Wireless Technology Letters. 33(6):675-678. https://doi.org/10.1109/LMWT.2023.323941967567833

Increased Activities against Biofilms of the Pathogenic Yeast Candida albicans of Optimized Pom-1 Derivatives

Antimicrobial peptides (AMPs) are an alternative group for the therapy of infectious diseases, with activity against a wide range of diverse pathogens. However, classical AMPs have significant side effects in human cells due to their unspecific pore formation in biomembranes. Nevertheless, AMPs are promising therapeutics and can be isolated from natural sources, which include sea and freshwater molluscs. The AMPs identified in these organisms show promising antimicrobial activities, as pathogens are mainly fought by innate defence mechanisms. An auspicious candidate among molluscs is the Cuban freshwater snail Pomacea poeyana, from which the peptides Pom-1 and Pom-2 have been isolated and studied. These studies revealed significant antimicrobial activities for both AMPs. Based on the activities determined, Pom-1 was used for further optimization. In order to meet the emerging requirements of improved anti-biofilm activity against naturally occurring Candida species, the six derivatives Pom-1A to F were developed and investigated. Analysis of the derivatives acting on the most abundant naturally occurring Candida yeast Candida albicans (C. albicans) revealed a strong anti-biofilm activity, especially induced by Pom-1 B, C, and D. Furthermore, a moderate decrease in the metabolic activity of planktonic yeast cells was observed