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91.
The effect of probiotic cultures over Listeria monocytogenes and Escherichia coli O157:H7 during yogurt storage was evaluated. Two different yogurt brands, one with additional probiotic cultures (Lactobacillus casei and L. acidophilus) were inoculated with known populations (106 UFC/g) of either L. monocytogenes or E. coli O157:H7 in three different times and stored for 32 days at 5 degrees C. Every four days the count of lactic bacteria, the added pathogens and pH was evaluated, according to the methodology described in the Bacteriological Analytical Manual. The pH and lactic bacteria population were constant during the testing period. Yogurt with additional probiotic cultures reduced the population of L. monocytogenes in 8 days, the population of E. coli O157:H7 in 16; yogurt with no additional probiotics took 20 days to reduce L. monocytogenes to non-detectable levels and even after 28 days of storage, E. coli O157:H7 was cultured. In this work, the beneficial effects of additional probiotic cultures in yogurt is confirmed again. 相似文献
92.
Estimation of soil water repellency of different particle size fractions in relation with carbon content by different methods 总被引:2,自引:0,他引:2
The water repellency of soils with different texture under different types of plant cover was determined by applying the WDPT and MED methods to both whole samples and the following size fractions: 2-1, 1-0.5, 0.5-0.25, 0.25-0.05 and <0.05 mm. Based on the results, the soils under maize crop and grassland, which were mostly wettable in the whole samples, exhibited water repellency in the finest fraction (<0.05 mm) as a result of its higher organic carbon content. On the other hand, all fractions in the forest soils, which were extremely water repellent, contributed to the overall repellency; in any case, the MED test revealed that the finest fraction was strongly repellent in the forest soils as well. 相似文献
93.
Pablo Salcedo-Abraira Sergio M.F.Vilela Artem A.Babaryk Maria Cabrero-Antonino Pedro Gregorio Fabrice Salles Sergio Navalon Hermenegildo Garcia Patricia Horcajada 《Nano Research》2021,14(2):450-457
A novel microporous two-dimensional(2D)Ni-based phosphonate metal-organic framework(MOF;denoted as IEF-13)has been successfully synthesized by a simple and green hydrothermal method and fully characterized using a combination of experimental and computational techniques.Structure resolution by single-crystal X-ray diffraction reveals that IEF-13 crystallizes in the triclinic space group Pi having bi-octahedra nickel nodes and a photo/electroactive tritopic phosphonate ligand.Remarkably,this material exhibits coordinatively unsaturated nickel(II)sites,free-P03H2and-P03H acidic groups,a C02accessible microporosity,and an exceptional thermal and chemical stability.Further,its in-deep optoelectronic characterization evidences a photoresponse suitable for photocatalysis.In this sense,the photocatalytic activity for challenging H2generation and overall water splitting in absence of any co-catalyst using UV-Vis irradiation and simulated sunlight has been evaluated,constituting the first report for a phosphonate-MOF photocatalyst.IEF-13 is able to produce up to 2,200 fimol of H2per gram using methanol as sacrificial agent,exhibiting stability,maintaining its crystal structure and allowing its recycling.Even more,170μmol of H2per gram were produced using IEF-13 as photocatalyst in the absence of any co-catalyst for the overall water splitting,being this reaction limited by the 02reduction.The present work opens new avenues for further optimization of the photocatalytic activity in this type of multifunctional materials. 相似文献
94.
María Liliana Ávalos-Rodríguez José Juan Alvarado-Flores Jorge Víctor Alcaraz-Vera José Guadalupe Rutiaga-Quiñones 《International Journal of Hydrogen Energy》2021,46(51):25909-25917
The objective of this work is to review the environmental and ecological policy instruments that Mexican legislation for existence of an Official Mexican Hydrogen Standard according to the premises motivates decarbonization. There is a worldwide interest in hydrogen (H2) and its incorporation into legal systems. In Mexico there are large legal gaps that question the legality of H2, because it is not recognized in a federal law and is only considered in technical standards of voluntary application. Also, Mexico has forest, agricultural, and livestock waste that, if properly used, can cover the energy demand of communities. The main findings of this study refer to the fact that, according to international standards for the management of H2 and taking into account the regulatory limitations in Mexico, it is possible to promote, an Official Mexican Standard exclusively aimed at establishing the minimum requirements for the design, construction, operation and maintenance of H2 storage, considering the areas of the opportunity offered by foreign experiences, according to the Mexican context. It is concluded that the parameters of legality exist in the instruments of environmental policy, to support the existence of an Official Mexican Standard of H2. 相似文献
95.
96.
In order to develop compact absorption refrigeration cycles driven by low heat sources, the simulated performance of a microchannel absorber of 5‐cm length and 9.5 cm3 in volume provided with a porous membrane is presented for 3 different solution‐refrigerant pairs: LiBr‐H2O, LiCl‐H2O, and LiNO3‐NH3. The high absorption rates calculated for the 3 solutions lead to large cooling effect to absorber volume ratios: 625 kW/m3 for the LiNO3‐NH3, 552 kW/m3 for the LiBr‐H2O, and 318 kW/m3 for the LiCl‐H2O solutions given the studied geometry. The performance of a complete absorption system is also analyzed varying the solution concentration, condensation temperature, and desorption temperature. The LiNO3‐NH3 and the LiBr‐H2O solutions provide the largest cooling effects. The LiNO3‐NH3 can work at a lower temperature of the heating source, in comparison with the one needed in a LiBr‐H2O system. The lowest cooling effect and coefficient of performance are found for the LiCl‐H2O solution, but this mixture allows the use of lower temperature heating sources (below 70°C). These results can be used for the selection of the most suitable solution for a given cooling duty, depending on the available heat source and condensation temperature. 相似文献
97.
Estefanía Rodríguez De Marco María Eugenia Steffolani Marcela Martínez Alberto E. León 《International Journal of Food Science & Technology》2018,53(2):499-507
Nannochloropsis is a microalga characterised by having high amounts of eicosapentaenoic acid (EPA), a fatty acid known for its health benefits. The aim of this study was to elaborate dry pasta with a significant contribution of EPA using Nannochloropsis sp., without affecting the quality product and with good consumer acceptance. Technological quality was analysed in terms of cooking properties and texture profile. Cooked pasta was characterised through proximal composition, phenolic compound, fatty acid content and sensorial analysis. It was possible to replace up to 30% of wheat flour with microalgae without affecting the technological quality of pasta and with a significant contribution of EPA to the daily diet (0.237 g per 100 g pasta). The incorporation of 10% and 20% Nannochloropsis in pasta formulation allowed to decrease the n6:n3 ratio from 25:1 to 5:1 and 2:1, respectively. Therefore, the microalgae are an interesting ingredient to increase EPA consumption in products like pasta, while the sensory evaluation confirms the possibility towards a commercial approach. 相似文献
98.
Meza-Espinoza Libier de los Ángeles Vivar-Vera María de Lourdes García-Magaña María Sáyago-Ayerdi Sonia G. Chacón-López Alejandra Becerrea-Verdín Eduardo M. Montalvo-González Efigenia 《Food science and biotechnology》2018,27(2):509-517
Food Science and Biotechnology - The enzymatic activity and partial characterization of proteases from Bromelia karatas fruits were evaluated and compared with Bromelia pinguin proteases. The... 相似文献
99.
Patsy V. Ramírez-González María Mercedes Zavala Arriaga Vladimir A. Escobar-Barrios 《Petroleum Science and Technology》2018,36(16):1242-1249
Interfacial tension and contact angle are two specific important parameters to take decisions for enhanced oil recovery, for instance, proper chemicals to use for surface tension reduction, expected wettability of solids, interaction between crude oil and rock. For this purpose, the article presents a method for easy calculation of the solid-liquid interfacial tension based on contact angle measurements applying Neumann's correlation and Young's equation. The main idea stands on the calculation of the rock parameters, like wettability, with known substances and extend these results to crude oils. It was possible, based on the results obtained, to establish a relationship between solid-liquid interfacial tension and contact angle for the crude oil – rock system, which can definitively be used for the calculation of interfacial tension of any other fluid spread out on the same kind of rock. A linear regression was obtained with an accuracy as good as R2 = 0.9989. Viscosity as a function of contact angle could also be obtained for the studied crude oils in the same kind of rock. 相似文献
100.
José M. León Blanco Pedro L. González-R Carmen Martina Arroyo García María José Cózar-Bernal Marcos Calle Suárez David Canca Ortiz 《Drug development and industrial pharmacy》2018,44(1):135-143
This work was aimed at determining the feasibility of artificial neural networks (ANN) by implementing backpropagation algorithms with default settings to generate better predictive models than multiple linear regression (MLR) analysis. The study was hypothesized on timolol-loaded liposomes. As tutorial data for ANN, causal factors were used, which were fed into the computer program. The number of training cycles has been identified in order to optimize the performance of the ANN. The optimization was performed by minimizing the error between the predicted and real response values in the training step. The results showed that training was stopped at 10?000 training cycles with 80% of the pattern values, because at this point the ANN generalizes better. Minimum validation error was achieved at 12 hidden neurons in a single layer. MLR has great prediction ability, with errors between predicted and real values lower than 1% in some of the parameters evaluated. Thus, the performance of this model was compared to that of the MLR using a factorial design. Optimal formulations were identified by minimizing the distance among measured and theoretical parameters, by estimating the prediction errors. Results indicate that the ANN shows much better predictive ability than the MLR model. These findings demonstrate the increased efficiency of the combination of ANN and design of experiments, compared to the conventional MLR modeling techniques. 相似文献