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951.
Gian Paulo G. Freschi Felipe M. Fortunato Carolina D. Freschi José Anchieta Gomes Neto 《Food Analytical Methods》2012,5(4):861-866
Tungsten permanent modifier with coinjection of Pd(NO3)2 and W–Ru permanent modifiers are proposed for the direct and simultaneous determination of As, Bi, Pb, Sb, and Se (group
1) and Co, Cr, Cu, Fe, and Mn (group 2), respectively, in milk by graphite furnace atomic absorption spectrometry. The performance
of modifiers was evaluated by means of thermal behavior of analytes, sensitivity, atomic signal profile, repeatability, graphite
tube lifetime, and background intensity. An air-assisted pyrolysis step was necessary to quantitative elimination of the organic
matter. After methods optimization, 14 commercial milk samples were analyzed. The found concentrations of As, Bi, Pb, Sb,
Se, Co, and Cr were lower than their limit of detection (2.13, 2.21, 1.49, 1.63, 2.05, 1.0, and 1.2 μg L−1, respectively). Concentrations of Cu, Fe, and Mn were in the 1.58–5.74 μg L−1, 9.79–49.3 μg L−1, and 2.25–4.08 μg L−1 intervals, respectively. The limits of detection for Cu, Fe, and Mn were 1.7, 5.3, and 2.0 μg L−1, respectively. The accuracy of methods was checked after analysis of two milk standard materials. Results for Cr, Cu, Fe,
Mn, Pb, and Mn were in agreement with certified values of SRMs at the 95% confidence level. Accuracy was also evaluated by
addition–recovery tests and recoveries in the 86–127% range were obtained for all elements. The use of pretreat platform of
graphite tubes with W or W–Ru allowed enlarging the lifetime of atomizer in 750 heating cycles. 相似文献
952.
Machulek AJ Moraes JE Vautier-Giongo C Silverio CA Friedrich LC Nascimento CA Gonzalez MC Quina FH 《Environmental science & technology》2007,41(24):8459-8463
The inhibition of the photo-Fenton (Fe2+/Fe3+, H2O2, UV light) degradation of synthetic phenol wastewater solutions by chloride ions is shown to affect primarily the photochemical step of the process, having only a slight effect on the thermal or Fenton step. Kinetic studies of the reactions of oxoiron (IV) (FeO2+) with phenol indicate that, if FeO2+ is formed in the photo-Fenton degradation, its role is probably minor. Finally, it is shown that, for both a synthetic phenol wastewater and an aqueous extract of Brazilian gasoline, the inhibition of the photo-Fenton degradation of the organic material in the presence of chloride ion can be circumvented by maintaining the pH of the medium at or slightly above 3 throughout the process, even in the presence of significant amounts of added chloride ion (0.5 M). 相似文献
953.
This study investigated the impact of thermoplastic extrusion on the nutritive quality of bovine rumen protein. Proximal composition, amino acid profile and in vivo true protein digestibility among rats were determined in raw (RBR) and extruded (EBR) rumen. Raw and extruded bovine rumen presented high percentages of protein (more than 95% on dry basis). Neither raw nor extruded proteins had any limiting amino acid, and the RBR and EBR amino acid scores were, respectively, 1.28 (leucine) and 1.25 (methionine plus cystine). Extrusion reduced significantly true protein digestibility from 97.7% to 93.1% (p < 0.001), but protein digestibility-corrected amino acid scores for both proteins (RBR and EBR) were 100%. Animal growth presented comparable profiles using raw and extruded rumen. In conclusion, thermoplastic extrusion did not affect the protein quality of bovine rumen, and this does not hinder the use of this material as a food ingredient. 相似文献
954.
Natale M Bisson C Monti G Peltran A Garoffo LP Valentini S Fabris C Bertino E Coscia A Conti A 《Molecular nutrition & food research》2004,48(5):363-369
Cow's milk allergy (CMA) has become a common disease in early childhood, its prevalence ranging from 1.6% to 2.8% among children younger than 2 years of age. The role of different cow's milk protein (CMP) in the pathogenesis of CMA is still controversial. Even if the proteins most frequently and most intensively recognized by immunoglobulin E (IgE) seem to be the most abundant in milk (caseins and beta-lactoglobulin), with an although great variability all milk proteins appear to be potential allergens, even those that are present in trace amounts (i.e., lactoferrin, IgG, and BSA). In this work proteomics techniques have been applied for CMP allergens analysis. Allergens have been identified by immunoblotting following resolution of CMP components by two-dimensional electrophoresis. Sera from 20 milk-allergic subjects, as proven by oral provocation test, CAP-RAST and skin prick test, have been used for cow's milk major allergen identification. Cow's milk proteins and their isoforms were identified by matrix assisted laser desorption/ionization-time of flight (MALDI-TOF)-mass spectrometry. In our group of patients, the prevalence of CMP allergens, i.e., the total number of subjects sensitized to CMP divided by the total number of the subjects enrolled in the study, was: 55% alpha(s1)-casein, 90% alpha(s2)-casein, 15% beta-casein, 50% kappa-casein, 45% beta-lactoglobulin, 45% BSA, 95% IgG-heavy chain, 50% lactoferrin, and 0% alpha-lactalbumin. 相似文献
955.
Pressureless Sintering of ZrB2 Prepared by Colloidal Processing: Particle Packing,Sintering Conditions,and Additives 下载免费PDF全文
Silvia Leo Carolina Tallon George V. Franks 《Journal of the American Ceramic Society》2016,99(12):3883-3892
Nonaqueous colloidal processing in cyclohexane and slip casting allowed the preparation of green ZrB2 compacts with 67.3% TD (theoretical density), which upon pressureless sintering at 2100°C densified to a final density of 92.4% TD. The effect of controllable sintering parameters (temperature, time, and heating rate) on the sintered properties of ZrB2 compacts prepared using the nonaqueous colloidal processing method was also studied, to maximize the sintered density and tailor the desired microstructure (i.e., dense final object with small grain size). The competition between pore elimination and grain growth mainly controls the final density achievable. ZrB2 compacts with maximum sintered densities of 93% TD could be achieved by controlling the sintering conditions. Finally, the use of carbon and B4C additives to improve the sintered density and microstructure of ZrB2 compacts was also investigated. The additives, compatible with colloidal processing, allowed compacts with greater sintered densities (96–98% TD) and finer grain sizes to be achieved by pressureless sintering, even at a lower temperature of 1900°C. 相似文献
956.
María E. Teresa-Rodrigo Juliane Eckhold Beatriz Puisac Andreas Dalski María C. Gil-Rodríguez Diana Braunholz Carolina Baquero María Hernández-Marcos Juan C. de Karam Milagros Ciero Fernando Santos-Simarro Pablo Lapunzina Jolanta Wierzba César H. Casale Feliciano J. Ramos Gabriele Gillessen-Kaesbach Frank J. Kaiser Juan Pié 《International journal of molecular sciences》2014,15(6):10350-10364
957.
María de los Angeles de Fernandez Verónica Carolina SotoVargas María Fernanda Silva 《Journal of the American Oil Chemists' Society》2014,91(12):2021-2033
Virgin olive oil has high levels of phenolic compounds that are highly bioavailable; these compounds are receiving considerable attention for their antioxidant activity, closely related to the prevention of non‐communicable chronic diseases. The aim of this work was to characterize the phenolic profile and antioxidant capacity of monovarietal olive oils cvs. Arauco, Arbequina, Farga and Empeltre produced in Argentina. This study focused on the relationship between the single molecules or classes of molecules quantified by SPE‐CZE, the corresponding Folin‐Ciocalteu results, and antioxidant capacity using three different tests. Fifteen compounds were simultaneously determined: tyrosol, vinylphenol, oleuropein, hydroxytyrosol, rutin, catechin, naringenin, cinnamic acid, chlorogenic acid, syringic acid, luteolin, apigenin, vanillin acid, quercetin, and caffeic acid. The phenolic contents of the monovarietal olive oils show significant differences between different varieties (p < 0.05), with positive and significant Pearson's correlation found between Folin–Ciocalteu and CZE. Besides, the correlation between the content of total polyphenols and antioxidant capacity was high for all the antioxidant assays performed. When analyzing the correlation coefficients of the different families of phenolic compounds studied, simple phenols and cinnamic acid derivatives show a higher correlation with antioxidant capacity. Thus, findings obtained in this study demonstrated that Arauco olive oil, autochthonous for Argentina, possesses the highest antioxidant/free‐radical scavenging properties, which are very likely due to the presence of high contents of phenolic compounds. 相似文献
958.
Manuel Jiménez-Melendo Carolina Clauss Arturo Donguez-Rodguez Antonio J. Sánchez-Herencia José S. Moya 《Journal of the American Ceramic Society》1997,80(8):2126-2130
Layered composites of alternate layers of pure Al2 O3 (thickness of 125 μ m) and 85 vol% Al2 O3 -15 vol% ZrO2 that was stabilized with 3 mol% Y2 O3 (thickness of 400 μ m) were obtained by sequential slip casting and then fired at either 1550° or 1700°C. Constant-strain-rate tests were conducted on these materials in air at 1400°C at an initial strain rate of 2 × 10-5 s-1 . The load axis was applied both parallel and perpendicular to the layer interfaces. Catastrophic failure occurred for the composite that was fired at 1700°C, because of the coalescence of cavities that had developed in grain boundaries of the Al2 O3 layers. In comparison, the composite that was fired at 1550°C demonstrated the ductility of the Al2 O3 +YTZP layer, but at a flow stress level that was determined by the Al2 O3 layer. 相似文献
959.
Lactobacillus casei is a group of phenotypically and genetically heterogeneous lactic acid bacteria, able to colonize various natural and man-made environments. Strains of the Lactobacillus casei group have been widely studied with respect to their health-promoting properties. Several beneficial functions for the human organism have been attributed to regular consumption of food products containing these strains. Bacteria of the Lactobacillus casei group are of great interest for the food industry to improve food quality. A number of studies have been conducted in order to evaluate the viability of strains of Lactobacillus casei group as probiotic in dairy products, desserts, among others food products. Despite its importance for the food industry, the taxonomy of the Lactobacillus casei group is still unclear. This review discusses important studies related to characterization of strains of Lactobacillus casei group, the application of these bacteria as probiotic in different food products and the main beneficial effects attributed to regular consumption of products containing such microorganisms. 相似文献
960.
Salvador Celedón Thierry Roisnel Isabelle Ledoux-Rak Jean-René Hamon David Carrillo Carolina Manzur 《Journal of Inorganic and Organometallic Polymers and Materials》2017,27(3):795-804
The new ionic heterotrimetallic unsymmetrically-substituted Schiff base complex [Ni{(η 5-Cp)Fe(η 5-C5H4)-C(=O)CH=C(4-HO-C6H4)NCH2CH2N=CH-(2-O-(η 6-C6H4)Ru(η 5-Cp*)}][PF6] (3; Cp = C5H5 and Cp* = C5(CH3)5) was prepared in 86% yield by a one-pot procedure by mixing equimolar amounts of 4-hydroxyphenyl functionalized ferrocenylenaminone 1, the organometallic aldehyde [(η 5-Cp*)Ru(η 6-2-HO-C6H4CHO)][PF6] (2) and nickel(II) acetate tetrahydrate in refluxing ethanol for 2 h. Its corresponding side-chain metallopolymer 4 was synthesized by reacting the organometallic-inorganic hybrid 3 with polyacrylic acid (DP = 25) in DMF at 110 °C for 48 h with an equimolar quantity of N,N′-dicyclohexylcarbodiimide and a catalytic amount of 4-dimethylaminopyridine. The new complex 3 was characterized by FT-IR and multidimensional NMR spectroscopy, elemental analysis and mass spectrometry. Single crystal X-ray diffraction analysis of 3 showed that the ferrocenyl and [(η 5-Cp*)Ru]+ units exhibit an anti-conformation and are almost coplanar with the unsymmetrical Schiff base complex fragment, while the 4-HO-C6H4 plane is almost perpendicular. The four-coordinate NiII metal ion adopts a square planar geometry, with two nitrogen and two oxygen donor atoms that are mutually trans. Size-Exclusion Chromatography established that metallopolymer 4 is formed of approximately three pendant ionic trimetallic units, while Differential Scanning Calorimetry and Thermal Gravimetric Analysis indicated that 3 and 4 are thermally stable with decomposition temperatures that exceed or border to 250 °C. Harmonic Light Scattering measurements at 1.91 µm incident wavelength showed that compounds 3 and 4 exhibit rather high second-order nonlinear responses, with hyperpolarizability β 1.91 values strongly increasing on passing from the monomeric unit 3 to its metallopolymeric counterpart 4. 相似文献