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81.
J. A. Rojas C. M. Rosell C. Benedito de Barber I. Pérez-Munuera M. A. Lluch 《European Food Research and Technology》2000,212(1):57-63
The evolution that the microstructure of the main components of wheat flour undergoes during the bread-making process was analysed by cryo scanning electron microscopy (cryo-SEM). The microstructure of wheat flour preserved some characteristics of the intact endosperm and consisted of aggregates of protein in which were embedded groups of cellular components. At the mixing stage, the dough appeared as a matrix of proteins and soluble solids with dispersed starch granules. Fermentation reinforced this matrix and improved the distribution of all the components. Special attention was paid to the complex microstructure of bread crumb. A continuous veil-like film that revealed the underlying structures lined the gas cells. Inside the gas cells large interconnecting cavities, characteristic of an open structure, were observed. The microstructure of the gas cell walls consisted of a very complex matrix with a rough and irregular appearance. Cryo-SEM proved to be a valuable tool that may allow a better understanding of the functional properties of dough as well as the quality attributes of bread. 相似文献
82.
Diego Francisco Cortés‐Rojas Claudia Regina Fernandes Souza Wanderley Pereira Oliveira 《International Journal of Food Science & Technology》2011,46(11):2420-2427
Response surface methodology was used to find the optimum ethanol concentration and temperature which maximises the antioxidant activity (AA) of hydroalcoholic extracts from aerial parts of Bidens pilosa L. A rotatable central composite design was used, and the extracts were characterised by the determination of solid concentration (SC), total flavonoid (TFC) and total polyphenol content (TPC). AA was determined through 2,2′‐azinobis (3‐ethylbenzothiazoline‐6‐sulphonic acid) diammonium salt (ABTS) and 2,2‐diphenyl‐1‐pycrylhydrazyl (DPPH) radical scavenging activity. Mathematical models showed the significant effects of each variable and allowed to select the optimum conditions of ethanol concentration (62.7%) and extraction temperature (66.2 °C). The optimised extract presented an AA of 804.9 ± 12.2 Trolox equivalent antioxidant capacity (TEAC) dry base (d.b.) for DPPH and 515.8 ± 31.8 TEAC d.b. for ABTS. It was observed that both TFC and TPC showed a good correlation with AA of the extracts. 相似文献
83.
Nicolette Pegels Isabel González Irene Martín María Rojas Teresa García Rosario Martín 《Food Control》2011,22(8):1189-1196
A TaqMan real-time polymerase chain reaction (PCR) method was developed for specific detection of bovine, ovine and caprine processed animal protein (PAP) in industrial feedstuffs. The method uses species-specific primers and probes targeting short mitochondrial D-loop sequences, and a positive amplification control based on 18S rRNA gene. The applicability of the real-time PCR protocol was assessed through analysis of 126 industrial feed samples that were manufactured to reproduce rendering processes of commercial feeds destined for farmed animals. The assay successfully classified samples as positive or negative according to the ruminant composition, enabling qualitative detection of banned material in feeds at levels as low as 0.1%. Although the method provides quantitative potential, results suggest that the real quantitative capability of the assay is limited by the existing variability in terms of composition and processing treatments of the feeds, which affect the amount and quality of amplifiable DNA. 相似文献
84.
Novel Use of Kaolin Wastes in Blended Cements 总被引:1,自引:0,他引:1
Olga Rodríguez Largo Raquel Vigil de la Villa Maria Isabel Sánchez de Rojas Moisés Frías 《Journal of the American Ceramic Society》2009,92(10):2443-2446
This paper describes the influence of different thermally activated clay wastes (ACW) on the hydration phases in cement pastes containing two percentages of addition (10% and 20%). Results show that the main products obtained during hydration of cement pastes containing ACW were portlandite, calcium aluminate hydrates, calcium silicate hydrates, and hydrotalcite-type compounds. Portlandite formation decreases when addition percentage is 20%, contrary to tetracalcium aluminate hydrate, which increases in similar conditions. The ACW that showed the most portlandite consumption was ACW1 (700°C, 2 h) according to thermogravimetric data. 相似文献
85.
Pomares H. Rojas I. Gonzalez J. Damas M. Pino B. Prieto A. 《Fuzzy Systems, IEEE Transactions on》2004,12(2):218-229
A novel approach to achieve real-time global learning in fuzzy controllers is proposed. Both the rule consequents and the membership functions defined in the premises of the fuzzy rules are tuned using a one-step algorithm, which is capable of controlling nonlinear plants with no prior offline training. Direct control is achieved by means of two auxiliary systems: The first one is responsible for adapting the consequents of the main controller's rules to minimize the error arising at the plant output, while the second auxiliary system compiles real input-output data obtained from the plant. The system then learns in real time from these data taking into account, not the current state of the plant but rather the global identification performed. Simulation results show that this approach leads to an enhanced control policy thanks to the global learning performed, avoiding overfitting. 相似文献
86.
V Martínez Vizcaíno F Salcedo Aguilar Y Jarabo Crespo P García Navalón C Cebrián Martínez V Domínguez Rojas 《Canadian Metallurgical Quarterly》1998,111(10):367-371
BACKGROUND: The aim of this study was to assess the familial aggregation of blood pressure and body mass index levels in schoolchildren of Cuenca city, Spain. SUBJECTS AND METHODS: A cross sectional study was made including 307 both sexes schoolchildren 9-12 years old recruited in three schools of Cuenca city, and 346 of their parents. There were determined sociodemographics variables, weight, height, body mass index, SBP, DBP and fasting plasma total cholesterol, cLDL, cHDL and triglyceride concentrations. RESULTS: Parents-children correlation coefficients in blood pressure levels ranged between -0.1 and 0.2. Parents-daughters correlations were stronger than parents-sons in ponderal indexes. The relationship of ponderal indexes and blood pressure between spouses was weak, with correlation coefficients between 0.08 y 0.1. By stepwise multiple regression analysis it was found that the only variable that explained a significant percentage of blood pressure variability (both systolic and diastolic) was the weight of the schoolchildren in both sexes. Parents body mass index explained more than 32% of body mass index daughter's variability. In sons any variable explained a significant percentage of variability. CONCLUSIONS: The parents-children aggregation of blood pressure is weak. Parents-children aggregation of ponderal indexes is stronger, though there are considerable sex-differences. Spouses relationship, though positive, is weak in all variables. 相似文献
87.
88.
Carlos Blanco Antonio Rojas Manuel Gomez Felicidad Ronda & Pedro Caballero 《International Journal of Food Science & Technology》2003,38(1):63-71
The chemistry of 2‐acetyl‐1,3‐cycloalkanediones has acquired increased applied importance because of the great number of applications in the agroalimentary industry. The keto‐enol ratios and equilibrium constants for proton reactions of 2‐acetyl‐1,3‐cyclopentanedione have been determined in solution using nuclear magnetic resonance and spectrophotometric methods. Chromium(iii ) is an essential nutrient and it seems that high chromium supplementation improves glucose tolerance. Chromium chelates have been shown to have a significant beneficial effect on metal status by increasing metal bioavailability in human diets. The composition and log β‐value of the complex formed in aqueous solution by chromium(iii ) with the ligand mentioned above have been determined. A detailed reaction scheme is proposed for the 1 : 1 chelation process. The kinetic data are consistent with a mechanism in which the mono‐enol tautomer of the ligand reacts with both metallic species, the fully hydrated metal ion and the Cr(OH)2+. The results are discussed in the light of previous work. 相似文献
89.
CG Acevedo A Huambachano E Perez S Rojas I Bravo E Contreras 《Canadian Metallurgical Quarterly》1997,18(5-6):387-392
It has been suggested that adenosine is involved in the acute effects of ethanol in a number of tissues. The present study was undertaken to evaluate the role of adenosine on the vascular responses of perfused isolated human placental cotyledons after the acute administration of ethanol. The possibility that ethanol may effect the uptake and metabolism adenosine was also investigated. Uptake of adenosine was studied using the single-circulation paired-tracer dilution technique. Both adenosine and ethanol caused a dose-related increase in perfusion pressure of placental lobules. Pharmacologically relevant concentrations of ethanol (10-65 mM) significantly inhibited the uptake of [3H]adenosine between 25 and 50 per cent. Thin-layer chromatographic analysis of the perfusate after the administration of ethanol showed in a 17.9 +/- 0.6 per cent reduction of [3H]adenosine metabolism. These findings support the working hypothesis that placental adenosine, at least partially, mediates the placental disturbance elicited by the administration of acute ethanol, which may contribute to the pathogenesis of fetal alcohol syndrome. 相似文献
90.
M Tsiang AK Jain KE Dunn ME Rojas LL Leung CS Gibbs 《Canadian Metallurgical Quarterly》1995,270(28):16854-16863
Utilizing site-directed mutagenesis, 77 charged and polar residues that are highly exposed on the surface of human thrombin were systematically substituted with alanine. Functional assays using thrombin mutants identified residues that were required for the recognition and cleavage of the procoagulant substrate fibrinogen (Lys21, Trp50, Lys52, Asn53 + Thr55, Lys65, His66, Arg68, Tyr71, Arg73, Lys77, Lys106 + Lys107, Asp193 + Lys196, Glu202, Glu229, Arg233, Asp234) and the anticoagulant substrate protein C (Lys21, Trp50, Lys65, His66, Arg68, Tyr71, Arg73, Lys77, Lys106 + Lys107, Glu229, Arg233), interactions with the cofactor thrombomodulin (Gln24, Arg70) and inhibition by the thrombin aptamer, an oligonucleotide-based thrombin inhibitor (Lys65, His66, Arg70, Tyr71, Arg73). Although there is considerable overlap between the functional epitopes, distinct and specific residues with unique functions were identified. When the functional residues were mapped on the surface of thrombin, they were located on a single hemisphere of thrombin that included both the active site cleft and the highly basic exosite 1. No functional residues were located on the opposite face of thrombin. Residues with procoagulant or anticoagulant functions were not spatially separated but interdigitated with residues of opposite or shared function. Thus thrombin utilizes the same general surface for substrate recognition regardless of substrate function although the critical contact residues may vary. 相似文献