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41.
Carolina Pereira Kechinski Cândida Raquel Scherrer Montero Pâmela Virgínia Ramos Guimarães Caciano Pelajo Zapata Noreña Lígia Damasceno Ferreira Marczak Isabel Cristina Tessaro Renar João Bender 《Food and Bioproducts Processing》2012,90(2):118-122
This study examined the effects of O3 and hot water treatments on the epidermis of Golden papaya fruit. Heat treatments were applied in a hot water brushing (HWB) system. Papayas were brushed under a pressurized hot water rinse stage at 45, 55 and 65 °C for 60 s. In the HWB treatment, 4 ppm ozone was applied to the papayas for 1 or 2 min. The results show that ozone applications did not affect the fruit's cuticular surface, while heat treatments allowed natural fissures on the fruit epidermis to recover. Several crystalloid forms were identified on the epidermis of the papayas after the heat treatments. The predominant crystalloid forms on papayas are tubular and there is a positive response to temperature; the higher the temperature, the larger and more frequent the tubular crystalloids. 相似文献
42.
Cristina Flox Javier Rubio-Garcia Raquel Nafria Reza Zamani Marcel Skoumal Teresa Andreu Jordi Arbiol Andreu Cabot Joan Ramon Morante 《Carbon》2012,50(6):2372-2374
Graphene-supported monometallic (Pt) and bimetallic (CuPt3) cubic nanocatalysts have been investigated as new positive electrode materials for improving the VO2+/VO2+ redox process occurring in the vanadium redox flow batteries (VRB). High-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) have been employed to characterize the electrodes. The presence of the CuPt3 nanocubes on graphene conferred higher electrocatalytic activity due to the much higher electroactive area compared to that obtained with the Pt nanoparticles. The electrochemical surface area of the nano-(CuPt3)-decorated graphene electrode was 105% higher compared to non-decorated graphene, being then a promising alternative for improving the VRB. 相似文献
43.
We explore the structure directing role of the chiral cation (1S,2S)-2-hydroxymethyl-1-benzyl-1-methylpyrrolidinium (SS-bmpm) in the synthesis of Al-containing zeolite materials in the presence of co-structure directing agents (co-SDAs). Three different co-SDAs are studied: tetramethylammonium (TMA), quinuclidine and sodium. Synthesis with TMA as co-SDA yields a ferrierite related phase and a material from the MWW family, where the SS-bmpm and the TMA cations are incorporated intact within the samples. Quinuclidine produces instead amorphous solids, while the use of Na+ leads to crystalline phases that crystallized as a result of the degradation of the SS-bmpm cation. A subsequent computational study based on molecular mechanics was performed in an attempt to unravel the location of TMA and SS-bmpm cations within the void space of the complex MWW structure. The results suggest that the sinusoidal channels are exclusively filled by TMA, while the bulky SS-bmpm cations can only be accommodated within the MWW super-cages, thus providing a new example of cooperative structure-directing effects of small and bulky cations in the synthesis of complex zeolite structures. 相似文献
44.
Raquel Herrero-Labrador Angel Trueba-Saiz Laura Martinez-Rachadell M
Estrella Fernandez de Sevilla Jonathan A. Zegarra-Valdivia Jaime Pignatelli Sonia Diaz-Pacheco Ana M. Fernandez Ignacio Torres Aleman 《International journal of molecular sciences》2020,21(24)
Obesity is a risk factor for Alzheimer’s disease (AD), but underlying mechanisms are not clear. We analyzed peripheral clearance of amyloid β (Aβ) in overweight mice because its systemic elimination may impact brain Aβ load, a major landmark of AD pathology. We also analyzed whether circulating insulin-like growth factor I (IGF-I) intervenes in the effects of overweight as this growth factor modulates brain Aβ clearance and is increased in the serum of overweight mice. Overweight mice showed increased Aβ accumulation by the liver, the major site of elimination of systemic Aβ, but unaltered brain Aβ levels. We also found that Aβ accumulation by hepatocytes is stimulated by IGF-I, and that mice with low serum IGF-I levels show reduced liver Aβ accumulation—ameliorated by IGF-I administration, and unchanged brain Aβ levels. In the brain, IGF-I favored the association of its receptor (IGF-IR) with the Aβ precursor protein (APP), and at the same time, stimulated non-amyloidogenic processing of APP in astrocytes, as indicated by an increased sAPPα/sAPPβ ratio after IGF-I treatment. Since serum IGF-I enters into the brain in an activity-dependent manner, we analyzed in overweight mice the effect of brain activation by environmental enrichment (EE) on brain IGF-IR phosphorylation and its association to APP, as a readout of IGF-I activity. After EE, significantly reduced brain IGF-IR phosphorylation and APP/IGF-IR association were found in overweight mice as compared to lean controls. Collectively, these results indicate that a high-fat diet influences peripheral clearance of Aβ without affecting brain Aβ load. Increased serum IGF-I likely contributes to enhanced peripheral Aβ clearance in overweight mice, without affecting brain Aβ load probably because its brain entrance is reduced. 相似文献
45.
46.
Raquel Ramos M. Pilar Pina Miguel Menndez Jesús Santamaría Gregory S. Patience 《加拿大化工杂志》2001,79(6):891-901
The reaction kinetics of the oxidative dehydrogenation of propane to propene over a V/MgO catalyst were studied. Both propane and propene oxidation kinetics were measured independently to quantify the rates of the parallel and consecutive reactions to propene and carbon oxides. Specific experiments to evaluate reaction products effects showed that water inhibited reaction rates but co‐feeding CO2 or propene had no measurable effect on selectivity or conversion. Kinetic data generated under integral reactor conditions and over an inert membrane reactor have also been used to estimate the kinetic parameters. Selectivity decreased as the oxygen partial pressure increased; however, propene yield was relatively insensitive to oxygen concentration. A dual site Mars‐van Krevelen model characterizes the reaction kinetics well. The role of lattice oxygen was established by alternating pulses of propane and oxygen. This redox model is able to predict the experimental tendencies observed in the three types of reactor studied. 相似文献
47.
MA. Patricia Muoz P. Mrcio D. Vargas Moiss M. Werlang I. Valria P. Yoshida Raquel S. Mauler 《应用聚合物科学杂志》2001,82(14):3460-3467
High‐density polyethylene (HDPE) was modified by the grafting of polydimethylsiloxane (PDMS) through a free‐radical process, in a melt‐mixer chamber, using dicumyl peroxide (DCP) as an initiator. The influence of PDMS (0.2–0.8 mol %) and peroxide (0.03–0.08 mol %) concentrations on the grafting, final torque, and melt flow rate (MFR) of copolymers were investigated using factorial planning. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), MFR, and rheometry were used to characterize the copolymers obtained. Surface plots showed that higher degrees of grafted PDMS and higher final torques were obtained with increase in the PDMS amount at low DCP levels and with increase in the DCP amount at low PDMS levels. The peaks of fusion and crystallization of the copolymers showed no significant changes with respect to HDPE. Data of MFR and GPC suggested that crosslinking reactions and/or chain extension occurred concomitant with the grafting reactions. Copolymers with high grafting degrees showed high MFR and low dynamic shear viscosities in comparison with low grafting degree copolymers, which is probably due to the migration of the PDMS‐containing copolymers on the surface. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3460–3467, 2001 相似文献
48.
Unai Iriarte‐Velasco Irene Sierra Emilio Atilano Cepeda Raquel Bravo Jose Luis Ayastuy 《Coloration Technology》2015,131(4):322-332
Bone is an inorganic template containing organic material inside which can be converted into hydroxyapatite‐rich material by pyrolysis. Nowadays, there is a growing research interest in the use of hydroxyapatite, the chemical formula of which is Ca10(PO4)6(OH)2. In the present work, pork bone, an abundant biomass source and food waste, has been converted into structured porous hydroxyapatite by a three‐step process including precharring under mild conditions, chemical activation, and thermal activation. The investigated activating agents were NaOH, KOH, K2CO3, H2SO4, and H3PO4. A thorough investigation of the influence of different activating protocols on the chemical and textural properties of the produced material was carried out by nitrogen adsorption–desorption at 77 K, potentiometric titrations, Fourier transform infrared, and X‐ray diffraction techniques. Chemical activation with NaOH, K2CO3, and H2SO4 increased the specific surface area up to 53%. H3PO4 reduced both surface area and pore volume, and KOH showed little influence on the pore structure. The produced materials were evaluated by methylene blue adsorption tests and showed significant improvement as a result of chemical activation. As a main effect, acid treatment increased methylene blue adsorption kinetics, probably owing to an increase in micropororosity, whereas alkali activation enhanced the adsorption capacity of the resultant biochar. 相似文献
49.
50.
Incorporation of chloramphenicol and captopril into poly(GL)‐b‐poly(GL‐co‐TMC‐co‐CL)‐b‐poly(GL) monofilar surgical sutures 下载免费PDF全文
Yolanda Márquez Tània Cabral Alice Lorenzetti Lourdes Franco Pau Turon Luís J. del Valle Jordi Puiggalí 《应用聚合物科学杂志》2017,134(17)
Incorporation of chloramphenicol and captopril into coated and uncoated monofilament sutures was evaluated, as well as the derived bactericide and wound healing effects. To this end, a commercially available suture and an amorphous random copolymer constituted by trimethylene carbonate and lactide units were considered. The suture had a segmented architecture based on polyglycolide hard blocks and a soft block constituted by glycolide, trimethylene carbonate and ε‐caprolactone units. Chloramphenicol was better loaded when the coating copolymer was employed due to its protective effect whereas captopril showed an opposite behavior due to partial solubilization during immersion in the coating bath. Interestingly, the release behavior was very different for the two studied drugs since a significant retention of chloramphenicol was always detected, suggesting the establishment of interactions between drug and copolymers. On the other hand, delivery of captopril showed a typical dose dependent behavior. A low in vitro toxicity of the two drugs was determined considering both epithelial‐like and fibroblast‐like cells. Bactericide effect of chloramphenicol against Gram‐negative and Gram‐positive bacteria was demonstrated at a dose that was non‐toxic for all assayed cells. An accelerating wound healing effect of captopril was also demonstrated for early events. In this case, the use of a coating copolymer was fundamental to avoid cytotoxic effects on highly loaded sutures. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44762. 相似文献