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排序方式: 共有906条查询结果,搜索用时 15 毫秒
811.
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
812.
Gema Pereira-Caro Andrés Madrona Laura Bravo José Luis Espartero Felipe Alcudia Arturo Cert Raquel Mateos 《Food chemistry》2009
The antioxidant activity of a new series of alkyl hydroxytyrosyl ethers was evaluated by the Rancimat test in a lipophilic food matrix and by the FRAP, ABTS and DPPH assays in a hydrophilic medium, and compared to free hydroxytyrosol (HTy), butylhydroxytoluene (BHT) and α-tocopherol. All methods used to assess the antioxidant activity of the new compounds emphasised the importance of the ortho-diphenolic structure on the maintenance of the high antioxidant activity associated with free HTy. The results obtained support the ‘polar paradox’ since the antioxidant activity of the lipophilic hydroxytyrosyl ethers was slightly lower in bulk oils and higher in hydrophilic media in comparison with their reference HTy. Although the length of the alkyl chain did not significantly affect the antioxidant activity in bulk oils, it did have a positive influence in hydrophilic medium for ethers with a short alkyl chain (methyl, ethyl and propyl), while ethers with longer alkyl chain (butyl, hexyl, octyl, dodecyl and octadecyl) maintained or even decreased their antioxidant activity, probably due to the steric effect of the side chains. In conclusion, these results show the strong antioxidant activity of a new group of lipophilic HTy derivatives that satisfies the food industry demands for new antioxidants with potential use as functional ingredients to improve the quality and nutritional properties of foods. 相似文献
813.
Biological evaluation and quantitative analysis of antioxidant compounds in pulps of the Amazonian fruits bacuri (Platonia insignis Mart.), ingá (Inga edulis Mart.), and uchi (Sacoglottis uchi Huber) by UHPLC‐ESI‐MS/MS 下载免费PDF全文
Flávio A. de Freitas Rafael C. Araújo Elzalina R. Soares Rita C. S. Nunomura Felipe M. A. da Silva Sarah R. S. da Silva Antonia Q. L. de Souza Afonso D. L. de Souza Francisco Franco‐Montalbán Leonard D. R. Acho Emerson S. Lima Giovana A. Bataglion Hector H. F. Koolen 《Journal of Food Biochemistry》2018,42(1)
Bacuri, ingá, and uchi are Amazon fruits consumed specially in the North region of Brazil. Due to their large consumption and the lack of knowledge regarding its chemical composition, these fruits were studied in relation to their Antioxidant chemical constitution. The total phenolic content ranged from 3.86 ± 0.47 to 33.38 ± 1.51 mg GAE/100 g, and the total flavonoid content ranged from 1.75 ± 0.22 to 19.44 ± 0.87 mg QUERE/100 g, where the contents showed a significant correlation with DPPH and ABTS antioxidant assays. Thus, UHPLC‐MS/MS was applied do quantify selected compounds, been citric acid the most abundant for all fruits. Furthermore, samples were screened for their α‐glycosidase and lipase inhibitory effects, in addition to their antimicrobial potentials. Bacuri showed the highest antioxidant and α‐glycosidase inhibitory capacity (IC50 15.20 μg/mL), whereas uchi and its main metabolite bergenin displayed moderate antimicrobial activities. The results shed light into the potentials of Amazonian fruit sources.
Practical applications
Plant phenolics are essential components of functional foods, due to their antioxidant and enzyme inhibition activities, which are directly linked to several diseases prevention. This is the first study about the quantification of antioxidant compounds in the Amazonian fruits: bacuri, ingá, and uchi. Although they are quite consumed in the North region of Brazil, there are no bio‐products made from them. This study aimed to elucidate the knowledge about the chemical composition and potentialities within these fruits with the practical purpose of highlighting them to future commercial applications. In addition, once we indicate their capabilities, we contribute with local populations in respect to the production of such fruits, which still is a family activity. 相似文献814.
Felipe G. Sanchez Mark Coleman Charles T. Garten Jr. Robert J. Luxmoore John A. Stanturf Carl Trettin Stan D. Wullschleger 《Biomass & bioenergy》2007,31(11-12):793-801
Soil carbon contents were measured on a short-rotation woody crop study located on the US Department of Energy's Savannah River Site outside Aiken, SC. This study included fertilization and irrigation treatments on five tree genotypes (sweetgum, loblolly pine, sycamore and two eastern cottonwood clones). Prior to study installation, the previous pine stand was harvested and the remaining slash and stumps were pulverized and incorporated 30 cm into the soil. One year after harvest soil carbon levels were consistent with pre-harvest levels but dropped in the third year below pre-harvest levels. Tillage increased soil carbon contents, after three years, as compared with adjacent plots that were not part of the study but where harvested, but not tilled, at the same time. When the soil response to the individual treatments for each genotype was examined, one cottonwood clone (ST66), when irrigated and fertilized, had higher total soil carbon and mineral associated carbon in the upper 30 cm compared with the other tree genotypes. This suggests that root development in ST66 may have been stimulated by the irrigation plus fertilization treatment. 相似文献
815.
Renewable energies (RE) represent a cornerstone to steer our energy system in the direction of sustainability and supply security. Generating electricity, heat or biofuels from renewable energy sources has become a high priority in the energy policy strategies at national level as well as at a global scale. Challenging goals for these “new” supply options to meet our energy demands have been set, e.g. at European level by the commitment of meeting 20% of the overall energy demand from renewable energy sources by 2020. 相似文献
816.
Rosana M. C. Bastos Antnio Simplício-Filho Christian Svio-Silva Luiz Felipe V. Oliveira Giuliano N. F. Cruz Eliza H. Sousa Irene L. Noronha Cristvo L. P. Mangueira Heloísa Quaglierini-Ribeiro Gleice R. Josefi-Rocha rika B. Rangel 《International journal of molecular sciences》2022,23(7)
Diabetes mellitus (DM) burden encompasses diabetic kidney disease (DKD), the leading cause of end-stage renal disease worldwide. Despite compelling evidence indicating that pharmacological intervention curtails DKD progression, the search for non-pharmacological strategies can identify novel targets for drug development against metabolic diseases. One of those emergent strategies comprises the modulation of the intestinal microbiota through fecal transplant from healthy donors. This study sought to investigate the benefits of fecal microbiota transplant (FMT) on functional and morphological parameters in a preclinical model of type 2 DM, obesity, and DKD using BTBRob/ob mice. These animals develop hyperglycemia and albuminuria in a time-dependent manner, mimicking DKD in humans. Our main findings unveiled that FMT prevented body weight gain, reduced albuminuria and tumor necrosis factor-α (TNF-α) levels within the ileum and ascending colon, and potentially ameliorated insulin resistance in BTBRob/ob mice. Intestinal structural integrity was maintained. Notably, FMT was associated with the abundance of the succinate-consuming Odoribacteraceae bacteria family throughout the intestine. Collectively, our data pointed out the safety and efficacy of FMT in a preclinical model of type 2 DM, obesity, and DKD. These findings provide a basis for translational research on intestinal microbiota modulation and testing its therapeutic potential combined with current treatment for DM. 相似文献
817.
Felipe Lpez-Saucedo Jesús Eduardo Lpez-Barriguete Guadalupe Gabriel Flores-Rojas Sharemy Gmez-Dorantes Emilio Bucio 《International journal of molecular sciences》2022,23(1)
Surface modification of polypropylene (PP) films was achieved using gamma-irradiation-induced grafting to provide an adequate surface capable of carrying glycopeptide antibiotics. The copolymer was obtained following a versatile two-step route; pristine PP was exposed to gamma rays and grafted with methyl methacrylate (MMA), and afterward, the film was grafted with N-vinylimidazole (NVI) by simultaneous irradiation. Characterization included Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and physicochemical analysis of swelling and contact angle. The new material (PP-g-MMA)-g-NVI was loaded with vancomycin to quantify the release by UV-vis spectrophotometry at different pH. The surface of (PP-g-MMA)-g-NVI exhibited pH-responsiveness and moderate hydrophilicity, which are suitable properties for controlled drug release. 相似文献
818.
ABSTRACT: We study the electrical characteristics of Macroporous Silicon/Transparent Conductor Oxide junctions obtained by the deposition of fluorine doped SnO2 onto macroporous silicon thin films, using the spray pyrolysis technique. Macroporous silicon was prepared by the electrochemical anodization of a silicon wafer to produce pores sizes ranging between 0.9 to 1.2 mum diameter. Scanning electronic microscopy was performed to confirm the pore filling and surface coverage. The transport of charge carriers through the interface was studied by measuring the current-voltage curves in dark and under illumination. In the best configuration we obtain a modest open circuit voltage of about 70 mV and a short circuit current of 3.5 mA/cm2 at illumination of 110 mW/cm2. In order to analyze the effects of the illumination on the electrical properties of the junction, we proposed a model of two opposing diodes, each one associated with an independent current source. We obtain a good accordance between experimental data and the model. The current-voltage curves on illumination conditions are well fitted with the same parameters obtained in dark where only the photocurrent intensities in the diodes are free parameters. 相似文献
819.
Characterization of Paracoccidioides brasiliensis PbDfg5p, a cell-wall protein implicated in filamentous growth 总被引:1,自引:0,他引:1
da Silva Castro N Barbosa MS Maia ZA Báo SN Felipe MS Santana JM Soares Mendes-Giannini MJ Pereira M de Almeida Soares CM 《Yeast (Chichester, England)》2008,25(2):141-154
The dimorphic fungus Paracoccidioides brasiliensis is the causative agent of the most frequent systemic mycosis in Latin America. In humans, infection starts by inhalation of fungal propagules, which reach the pulmonary epithelium and differentiate into the yeast parasitic phase. Here we describe the characterization of a Dfg5p (defective for filamentous growth) homologue of P. brasiliensis, a predictable cell wall protein, first identified in Saccharomyces cerevisiae. The protein, the cDNA and genomic sequences were analysed. The cloned cDNA was expressed in Escherichia coli and the purified rPbDfg5p was used to obtain polyclonal antibodies. Immunoelectron microscopy and biochemical studies demonstrated the presence of PbDfg5p in the fungal cell wall. Enzymatic treatments identified PbDfg5p as a beta-glucan linked protein that undergoes N-glycosylation. The rPbDfg5p bound to extracellular matrix components, indicating that those interactions could be important for initial steps leading to P. brasiliensis attachment and colonization of host tissues. 相似文献
820.
Felipe A. Canut Alda M.P. Simes Luis Reis Manuel Freitas Ivan N. Bastos Fbio C. Castro Edgar N. Mamiya 《Fatigue & Fracture of Engineering Materials & Structures》2019,42(11):2509-2519
The study deals with degradation and failure of mooring chains by the combined effect of corrosion and mechanical cyclic stresses on steel. Monitoring of the corrosion‐fatigue damage was carried out using electrochemical assessment during the application of the cyclic mechanical loading on grade R4 martensitic steel specimens, immersed in artificial seawater. The spontaneous potential of the steel specimens and Electrochemical Impedance Spectroscopy measurements were performed to assess the corrosion degradation. Tests conducted under fully reversed stress‐controlled loading have shown earlier failure caused by the corrosive environment when compared with the tests performed in ambient air. The corrosion potential response was used to identify the crack initiation and propagation stages. 相似文献