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91.
Ignacio Vieitez Nicolas Callejas Bruno Irigaray Yenny Pinchak Natalie Merlinski Iván Jachmanián Maria A. Grompone 《Journal of the American Oil Chemists' Society》2014,91(4):655-664
The cost of starting materials for the production of biodiesel is typically 75 % of the final retail price. Oils previously used for frying, waste frying oils (WFO), are a very suitable resource. Repetitive use of oil for frying foods involves high temperature, moisture and aeration for extended periods. The most important deterioration processes triggered by these conditions are hydrolysis and oxidation. In this study, 24 WFO samples of different origins were analyzed and classified as potential starting materials for biodiesel production using three quality parameters representing the main factors that affect the conversion of WFO. These parameters were: acid value, content of polar compounds and content of polymers, which varied in the ranges from 0.2 to 7.6, 14.9 to 43.2 and 0.9 to 15.2 %, respectively. Ester content obtained using conventional transesterification (TE) for WFO conversion decreased with increased levels of WFO deterioration determined by any of the three parameters noted above. TE products obtained had ester content between 81.4 and 95.7 %. Total ester content of a WFO sample with relatively low %AV could be increased to 96.5 % using a two-stage base catalysis TE. Finally, conversion of WFO samples resulted in ester contents of 89.0 and 91.3 %, respectively, when transesterified by conventional TE. After blending up to 10 % with refined oil, the ester content achieved was near 96.5 %. Thus, the blending represents an alternative for obtaining a product with suitable ester content. 相似文献
92.
93.
Luis Ignacio Rizzi 《Networks and Spatial Economics》2008,8(2-3):125-140
Assuming that both road safety and travel time are a function of traffic density and care from a driver’s standpoint, a theoretical framework is developed. First, an expected-utility framework is developed to study the optimal choice of care by a rational driver. Second, the subjective value of traffic density is derived as a measure of drivers’ willingness to pay for simultaneous road safety improvements and travel time savings. Third, the above results are revisited when car insurance is available. Fourth, a simple cost-benefit analysis rule of road capacity expansion is derived when moral hazard is present. 相似文献
94.
Traditional underground wine cellars are a good example of bioclimatic construction, providing optimum conditions for maturing wine with no energy consumption. This article studies the annual thermal behaviour of traditional underground wine cellars in one of the most well-known wine producing areas in Spain, the Ribera del Duero. For this we have applied a method based on multiple regression analysis using experimental data monitored for 1 year. The results show that the interior air temperature is fundamentally conditioned by the undisturbed temperature of the ground at the average depth of the wine cellar and by the temperature of the outside air (R2 varies between 0.937 and 0.974, with an average of 0.964 for the three wine cellars studied). However, the stability of the wine cellar during changes of outside temperature differs according to the time of year. In the spring and summer, the stability is excellent and the influence of the ground temperature is much greater than that of the outside air temperature (beta coefficient for the ground temperature is 0.85 compared to 0.17 for the outside air temperature). In the autumn and winter, the stability of the wine cellar is reduced by the increased ventilation, reducing the influence of the ground temperature (β = 0.70) and increasing that of the outside air (β = 0.42). 相似文献
95.
Mohammed ElKaoutit Ahmed Hosny Naggar Ignacio Naranjo-Rodriguez Manuel Dominguez José Luis Hidalgo-Hidalgo de Cisneros 《Synthetic Metals》2009,159(5-6):541-545
In this paper we investigate the nano-characterization of polypyrrole (Ppy) thin film electro-synthesized on highly oriented pyrolitic graphite (HOPG) with and without horseradish peroxidase enzyme (HRP) using Atomic force microscopy (AFM) performed in contact mode and fluid cell with electrolyte and potential control (ECAFM). In situ electro-synthesis of thin polypyrrole film was made by cyclic volt–amperommetry achieving structured Ppy nanoparticles with two types of particle sizes and the same ellipsoidal shape. Furthermore, the electro-immobilization of HRP, onto this film, was made at a fixed potential, achieving different morphology characterized by highly rough, non-homogeneous structure, and partial maintaining of the ellipsoidal particle in specific sites. The effect of polarization time on morphological parameters was studied and two mechanisms of electro-immobilization of HRP with Ppy conducting polymers were proposed. 相似文献
96.
Arantxa Rodriguez-Casado Pedro Carmona Pilar Moreno Ignacio Sánchez-González Antonella Macagnano Corado Di Natale Mercedes Careche 《Food chemistry》2007,103(3):1024-1030
Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy has been used for the first time to evaluate the postmortem changes in structure of components from sardine muscle in relation to quality loss. Sardines (Sardina pilchardus) were stored in ice for up to thirteen days. The spectroscopic study was focussed on the structural changes produced on the lipids and proteins. 相似文献
97.
Ignacio Fernández‐Fígares María A García Raquel Ruiz Luis A Rubio 《Journal of the science of food and agriculture》2008,88(5):870-876
BACKGROUND: Iberian pig production is linked to the use of the Mediterranean woodland, where the use of local feed resources is of paramount importance for the sustainability of the system. The aim of the present work was to explore the potential of triticale cv. Camarma as compared to barley cv. Esgueva in Iberian pig feeding by studying their respective ileal digestibilities of amino acids and carbohydrates in animals cannulated at the end of the ileum. RESULTS: Leu, Met and Tyr had (P < 0.05) greater standardised ileal digestibilities (SID) in pigs fed triticale diet. There was a trend (P = 0.07) towards greater SID of Thr in pigs fed the barley diet. The least digestible indispensable amino acids were Ile (74.6% SID) for barley and Thr (78.9% SID) for triticale. Except for β‐glucans, apparent ileal digestibilities (AIDs) of individual non‐starch polysaccharide (NSP), sugars and starch were greater in pigs fed triticale (P < 0.05). Nevertheless, total amounts of NSP digested were greater in pigs fed the barley diet (P < 0.05). CONCLUSION: Overall, triticale cv. Camarma had greater amino acid and carbohydrate AID than barley cv. Esgueva and may represent a valuable grain for Iberian pig feeding. Copyright © 2008 Society of Chemical Industry 相似文献
98.
José A Pérez Alberto González J Miguel Oliva Ignacio Ballesteros Paloma Manzanares 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2007,82(10):929-938
BACKGROUND: Crop residues as wheat straw are potential sources for fuel‐ethanol production as an alternative to current production based on starch‐ or sugar‐containing feedstocks. In this work, the effect of liquid hot water (LHW) process parameters, i.e. temperature (170 and 200 °C), residence time (0 and 40 min), solid concentration (5% and 10% (w/v)) and overpressure applied in the reactor (30 bar and no overpressure), on pretreatment of wheat straw was studied using a full factorial experimental design. Pretreatment effectiveness was evaluated based on the composition of the solid and liquid fractions obtained after filtration of pretreated material, and the susceptibility of the solid fraction to enzymatic hydrolysis (EH) using commercial cellulases. RESULTS: Statistical analysis showed that only temperature and time, within the limits of the experimental range, have a significant effect on the responses studied. While the effect of pretreatment time in hemicellulose‐derived sugar recovery in prehydrolyzate depends on temperature, EH yield was enhanced as both temperature and time were increased. Maximum EH yield was 96 g glucose per 100 g potential glucose in pretreated residue. Xylan and acetyl groups content remaining in solid residue after pretretament, which were found to be directly correlated, had a marked effect on pretreated substrate degradability. CONCLUSIONS: LHW is an effective pretreatment to enhance the potential of wheat straw as substrate for ethanol production. Maximum hemicellulose‐derived sugar recovery (53% of content in raw material) and EH yield (96% of theoretical) fall within different temperature and time intervals, suggesting separate optimization designs for these responses. Copyright © 2007 Society of Chemical Industry 相似文献
99.
Ternary systems consisting of blends of polycarbonate (PC) from bisphenol A and minority amounts of an amorphous polyamide reinforced with organically modified nanoclay (naPA), were obtained in the melt state. The nanoclay was widely exfoliated inside the dispersed naPA phase. The dispersed phase exhibited a very fine size (up to 0.36 µm), indicating compatibilization. Compatibilization was attributed to interactions between the aPA and the PC. The nanocomposite showed a lower compatibility than their corresponding blends. This lower compatibility of the nanocomposite was attributed to a hindrance of the interaction by the migrated surfactant of the organoclay. The presence of fibrillation in conjunction with a dispersed nanoclay resulted in additive enhancing effects on the modulus and yield stress. This led to modulus increases up to 46% with respect to that of the neat matrix upon the addition of 25% naPA‐10. Besides exhibiting these remarkable modulus values, these systems show an elongation at break similar to that of the neat PC matrix.
100.
Diego A. Vasco Carlos Salinas-Lira Ignacio Barra-Reyes Diego M. Elustondo 《Holz als Roh- und Werkstoff》2018,76(5):1461-1469
This paper reports on the properties of Pinus radiata wood impregnated with an organic phase change material (O-PCM). The tests are aimed at characterizing the kinetics of impregnation (rates, flows, and fronts) and the thermophysical properties (thermal conductivity and specific heat). In particular, a paraffin type O-PCM (octadecane) is used to impregnate dry radiata pine wood in the tangential flow direction at four manometric pressures (0, 1, 2, and 3 bar) and constant temperature of 50 °C. The wood is sapwood from 12-year old P. radiata growing in the Bío-Bío region and dimensioned according to Chilean standard for treated wood sample extraction. The results show that it is viable to impregnate P. radiata wood with O-PCM to improve its thermophysical properties with the purpose of passive conditioning. 相似文献