314 research outputs found

    Langmuir-Blodgett Films of the Metal-Organic Framework MIL-101(Cr): Preparation, Characterization, and CO2 Adsorption Study Using a QCM-Based Setup

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    This work reports the fabrication and characterization of Langmuir–Blodgett films of nanoparticles (size 51 ± 10 nm) of the metal organic framework MIL-101(Cr). LB film characterization by SEM, UV–vis, GIXRD, and QCM has shown that the addition of 1 wt % of behenic acid to MOF dispersion allows obtaining dense monolayers at the air–water interface that can be deposited onto solid substrates of different nature with transfer ratios close to 1. Moreover, a QCM-based setup has been built and used for the first time to measure CO2 adsorption isotherms at 303 K on MOF LB films, proving that LB films with MOF masses between 1.2 (1 layer) and 2.3 (2 layers) µg can be used to obtain accurate adsorption values at 100 kPa, similar to those obtained by conventional adsorption methods that require much larger MOF quantities (tens of milligrams)

    The mediterranean biotypes of Tylenchulus semipenetrans in Spanish citrus orchards

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    Les capacités de reproduction de quatorze populations du nématode des citrus (#Tylenchulus semipenetrans$) collectées dans la principale zone de citriculture de l'Espagne ont été comparées sur oranger amer et citrange Carrizo. Toutes les populations ont été identifiées comme appartenant au biotype méditerranéen. La capacité de reproduction varie considérablement en fonction des populations. Le pouvoir infestant et le taux de reproduction des populations collectées dans la rhizosphère des porte-greffes citranges Troyer ou Carrizo sont plus élevés (P supérieur ou égal à 0,05) que ceux des populations collectées sur oranger amer. (Résumé d'auteur

    Synthesis and gas adsorption properties of mesoporous silica-NH2-MIL-53(Al) core-shell spheres

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    Ordered mesoporous silica-NH2-MIL-53(Al) core-shell spheres of about 4 µm in diameter have been synthesized by seeding the corresponding mesoporous silica spheres (MSSs) with crystals of NH2-MIL-53(Al) and subsequent secondary crystal growth into a MOF shell. The morphology of the particles was analyzed by SEM, while TGA, EDX and XRD characterizations gave information on the composition and structure of this material and the activation of the MOF. N2 adsorption analysis revealed that the NH2-MIL-53(Al) shell controlled the access of guest molecules into the hydrophilic silica mesoporous structure, while the breathing behavior of the microporous NH2-MIL-53(Al) shell was confirmed by CO2 adsorption isotherms

    Characterization of soil suppressiveness to root knot nematodes in organic horticulture in plastic greenhouse

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    The fluctuation of Meloidogyne population density and the percentage of fungal egg parasitism were determined from July 2011 to July 2013 in two commercial organic vegetable production sites (M10.23 and M10.55) in plastic greenhouses, located in northeastern Spain, in order to know the level of soil suppressiveness. Fungal parasites were identified by molecular methods. In parallel, pot tests characterized the level of soil suppressiveness and the fungal species growing from the eggs. In addition, the egg parasitic ability of 10 fungal isolates per site was also assessed. The genetic profiles of fungal and bacterial populations from M10.23 and M10.55 soils were obtained by Denaturing Gradient Gel Electrophoresis (DGGE), and compared with a non-suppressive soil (M10.33). In M10.23, Meloidogyne population in soil decreased progressively throughout the rotation zucchini, tomato, and radish or spinach. The percentage of egg parasitism was 54.7% in zucchini crop, the only one in which eggs were detected. Pochonia chlamydosporia was the only fungal species isolated. In M10.55, nematode densities peaked at the end of the spring-summer crops (tomato, zucchini, and cucumber), but disease severity was lower than expected (0.2-6.3). The percentage of fungal egg parasitism ranged from 3 to 84.5% in these crops. The results in pot tests confirmed the suppressiveness of the M10.23 and M10.55 soils against Meloidogyne. The number of eggs per plant and the reproduction factor of the population were reduced (P < 0.05) in both non-sterilized soils compared to the sterilized ones after one nematode generation. P. chlamydosporia was the only fungus isolated from Meloidogyne eggs. In in vitro tests, P. chlamydosporia isolates were able to parasitize Meloidogyne eggs from 50 to 97% irrespective of the site. DGGE fingerprints revealed a high diversity in the microbial populations analyzed. Furthermore, both bacterial and fungal genetic patterns differentiated suppressive from non-suppressive soils, but the former showed a higher degree of similarity between both suppressive soils than the later

    Fabrication of ultrathin films containing the metal organic framework Fe-MIL-88B-NH2 by the Langmuir-Blodgett technique

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    In this work, the fabrication of ultrathin films containing the metal organic framework (MOF) Fe-MIL- 88B-NH2 by the Langmuir–Blodgett (LB) technique has been explored. MOF crystals of two different sizes (1.5 ± 0.3 and 0.07 ± 0.01 µm) have been synthesized and assembled at the air–liquid interface by the LB method. The effect of the subphase pH and particle size on the film formation process has been studied. Moreover, for the first time, mixed MOF+polymer (the commercial soluble polyimide Matrimid®) LB films containing different MOF loadings have been fabricated. These experiments show that it is possible to obtain ultrathin MOF + polymer films with a controlled MOF density. Furthermore, MOF particles are homogeneously distributed in the polymer matrix, even with very large amounts of MOF (up to 95 wt%). LB films have been incorporated into materials of different nature, including glass and mica substrates and also polymeric membranes based on polysulfone Udel® and PIM-1 (polymer of intrinsic microporosity), and the modification of water contact angle after LB film deposition has been analyzed

    Aerosol radiative effects in the ultraviolet, visible, and near-infrared spectral ranges using long-term aerosol data series over the Iberian Peninsula

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    A better understanding of aerosol radiative properties is a crucial challenge for climate change studies. This study aims at providing a complete characterization of aerosol radiative effects in different spectral ranges within the shortwave (SW) solar spectrum. For this purpose, long-term data sets of aerosol properties from six AERONET stations located in the Iberian Peninsula (southwestern Europe) have been analyzed in terms of climatological characterization and inter-annual changes. Aerosol information was used as input for the libRadtran model in order to determine the aerosol radiative effect (ARE) at the surface in the ultraviolet (AREUV), visible (AREVIS), near-infrared (ARENIR), and the entire SW range (ARESW) under cloud-free conditions. Over the whole Iberian Peninsula, yearly aerosol radiative effects in the different spectral ranges were found to be −1.1 < AREUV < −0.7, −5.7 < AREVIS < −3.5, −2.6 < ARENIR < −1.6, and −8.8 < ARESW < −5.7 (in W m−2). Monthly means of ARE showed a seasonal pattern with larger values in spring and summer. The aerosol forcing efficiency (AFE), ARE per unit of aerosol optical depth, has also been evaluated in the four spectral ranges. AFE exhibited a dependence on single scattering albedo as well as a weaker one on the Ångström exponent. AFE is larger (in absolute value) for small and absorbing particles. The contributions of the UV, VIS, and NIR ranges to the SW efficiency varied with the aerosol types. The predominant aerosol size determined the fractions AFEVIS/AFESW and AFENIR/AFESW. The AFEVIS was the dominant contributor for all aerosol types, although non-absorbing large particles caused more even contribution of VIS and NIR intervals. The AFEUV / AFESW ratio showed a higher value in the case of absorbing fine particles

    Delayed gastric emptying after classical Whipple or pylorus-preserving pancreatoduodenectomy: a randomized clinical trial (QUANUPAD)

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    Purpose Pylorus-preserving pancreatoduodenectomy (PPPD) has been the gold standard for pancreatic head lesion resection for several years. Some studies have noted that it involves more delayed gastric emptying (DGE) than classical Whipple (i.e., pancreatoduodenectomy with antrectomy). Our working hypothesis was that the classical Whipple has a lower incidence of DGE. We aimed to compare the incidence of DGE among pancreatoduodenectomy techniques. Methods This pragmatic, randomized, open-label, single-center clinical trial involved patients who underwent classical Whipple (study group) or PPPD (control group). Gastric emptying was clinically evaluated using scintigraphy. DGE was defined according to the International Study Group of Pancreatic Surgery (ISGPS) criteria. The secondary endpoints were postoperative morbidity, length of hospital stay, anthropometric measurements, and nutritional status. Results A total of 84 patients were randomized (42 per group). DGE incidence was 50% (20/40, 95% confidence interval (95% CI): 35-65%) in the study group and 62% (24/39, 95% CI: 46-75%) in the control group (p = 0.260). No differences were observed between both groups regarding postoperative morbidity or length of hospital stay. Anthropometric measurements at 6 months post-surgery: triceps fold measurements were 12 mm and 16 mm (p = 0.021). At 5 weeks post-surgery, triceps fold measurements were 13 mm and 16 mm (p = 0.020) and upper arm circumferences were 26 cm and 28 cm (p = 0.030). No significant differences were observed in nutritional status. Conclusion DGE incidence and severity did not differ between classical Whipple and PPPD. Some anthropometric measurements may indicate a better recovery with PPPD
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