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排序方式: 共有1735条查询结果,搜索用时 46 毫秒
51.
Marta Oliveira Susana Casal Simone Morais Cláudia Alves Filipa Dias Sandra Ramos Eulália Mendes Cristina Delerue-Matos M. Beatriz P.P. Oliveira 《Food chemistry》2012,130(3):702-709
The present paper reports the amount and estimated daily mineral intake of nine elements (Ca, Mg, K, Na, P, Fe, Mn, Cr and Ni) in commercial instant coffees and coffee substitutes (n = 49). Elements were quantified by high-resolution continuum source flame (HR-CS-FAAS) and graphite furnace (HR-CS-GFAAS) atomic absorption spectrometry, while phosphorous was evaluated by a standard vanadomolybdophosphoric acid colorimetric method.Instant coffees and coffee substitutes are rich in K, Mg and P (>100 mg/100 g dw), contain Na, Ca and Fe in moderate amounts (>1 mg/100 g), and trace levels of Cr and Ni. Among the samples analysed, plain instant coffees are richer in minerals (p < 0.001), except for Na and Cr. Blends of coffee substitutes (barley, malt, chicory and rye) with coffee (20–66%) present intermediate amounts, while lower quantities are found in substitutes without coffee, particularly in barley.From a nutritional point of view the results indicate that the mean ingestion of two instant beverages per day (total of 4 g instant powder), either with or without coffee, cannot be regarded as important sources of minerals to the human diet, although providing a supplementation of some minerals, particularly Mg and Mn in instant coffees. Additionally, and for authentication purposes, the correlations observed between some elements and the coffee percentage in the blends, with particular significance for Mg amounts, provides a potential tool for the estimation of coffee in substitute blends. 相似文献
52.
Carolina Pereira Kechinski Cândida Raquel Scherrer Montero Pâmela Virgínia Ramos Guimarães Caciano Pelajo Zapata Noreña Lígia Damasceno Ferreira Marczak Isabel Cristina Tessaro Renar João Bender 《Food and Bioproducts Processing》2012,90(2):118-122
This study examined the effects of O3 and hot water treatments on the epidermis of Golden papaya fruit. Heat treatments were applied in a hot water brushing (HWB) system. Papayas were brushed under a pressurized hot water rinse stage at 45, 55 and 65 °C for 60 s. In the HWB treatment, 4 ppm ozone was applied to the papayas for 1 or 2 min. The results show that ozone applications did not affect the fruit's cuticular surface, while heat treatments allowed natural fissures on the fruit epidermis to recover. Several crystalloid forms were identified on the epidermis of the papayas after the heat treatments. The predominant crystalloid forms on papayas are tubular and there is a positive response to temperature; the higher the temperature, the larger and more frequent the tubular crystalloids. 相似文献
53.
Taimur Gibran Rabuske Saeid Nooshabadi Cesar Ramos Rodrigues 《Analog Integrated Circuits and Signal Processing》2012,72(1):37-46
This paper aims to address the growing need for ultra-low power analog-to-digital converters (ADC). For this purpose, we pushed the limitations of conventional successive approximation register ADCs through the use of deep voltage scaling, a novel iterative precharging scheme, and topological improvements over recent works. From the simulations results we achieve a figure of merit of 31?fJ per conversion step, with an 8.45 effective number of bits, working at 5?MSps. 相似文献
54.
Carmen M González‐Henríquez Luis H Tagle Claudio A Terraza Ángel Leiva Andrés Barriga González Ulrich G Volkmann Alejandro L Cabrera Esteban Ramos‐Moore Maximiliano Pavez‐Moreno 《Polymer International》2012,61(5):810-817
Polyesters were synthesized by direct polycondensation of thiophene‐2,5‐dicarboxylic acid and five different silarylene‐containing diphenols using a tosyl chloride/pyridine/N,N‐dimethylformamide system as a condensing agent. Polymers were obtained in good yields and were characterized using Fourier transform infrared and NMR (1H, 13C, 135‐DEPT and 29Si) spectroscopy and elemental analysis. All polymers were completely soluble in aprotic organic polar solvents such as dimethylformamide, dimethylsulfoxide and N‐methyl‐2‐pyrrolidone. The range of effective mass of the polymers (m/z) was 1 × 105–2 × 105, determined using electrospray ionization mass spectrometry. Asymmetry and steric hindrance prevented dense packing of the polymeric chains, showing glass transition temperatures between ? 78 and ? 51 °C and loss of thermal stability at 177–199 °C (10% weight loss). Additionally, the melting points of the polyesters were found to be in the range 62–67 °C. Because of this, the samples were semi‐solid at room temperature. The optical band gaps of the polymers were observed between 4.54 and 4.48 eV, corresponding in all cases to insulator behavior. The molecular structure of the samples was studied using X‐ray diffraction, showing a degree of order that was associated with two monoclinic lattices. Additionally, the conductivity was studied using a two‐point method with contacts on top of polymer films. Prior to the electrical measurement, the samples were polarized in an external electric field of 0.8 to 6.4 V cm?1, and the alignment of the dipoles increased the electrical conductivity. Copyright © 2012 Society of Chemical Industry 相似文献
55.
Daiana Garcia Germán Barros Sofía Chulze Antonio J. Ramos Vicente Sanchis Sonia Marín 《Journal of the science of food and agriculture》2012,92(15):2952-2959
BACKGROUND: Fusarium graminearum and F. verticillioides are two very important mycotoxigenic species as they cause diverse diseases in crops. The effects of constant and cycling temperatures on growth and mycotoxin production of these species were studied on soybean based medium and on irradiated soya beans. RESULTS: F. graminearum grew better when was incubated at 15, 20 and 15–20 °C (isothermal or cycling temperature) during 21 days of incubation. Maximum levels of zearalenone and deoxynivalenol (39.25 and 1040.4 µg g?1, respectively) were detected on soya beans after 15 days of incubation and the optimal temperature for mycotoxin production was 15 °C for zearalenone and 20 °C for deoxynivalenol. F. verticillioides grew better at 25 °C in culture medium and at 15/20 °C and 15/25 °C on soybean seeds. Fumonisin B1 was produced only in culture medium, and the maximum level (7.38 µg g?1) was found at 15 °C after 7 days of incubation. CONCLUSION: When growth and mycotoxin production under cycling temperatures were predicted from the results under constant conditions, observed values were different from calculated for both species and substrate medium. Therefore, care should be taken if data at constant temperature conditions are to be extrapolated to real field conditions. Copyright © 2012 Society of Chemical Industry 相似文献
56.
57.
Sónia Simões Filomena Viana Mustafa Koçak A. Sofia Ramos M. Teresa Vieira Manuel F. Vieira 《Journal of Materials Engineering and Performance》2012,21(5):678-682
In this article, the characterization of the interfacial structure of diffusion bonding a TiAl alloy is presented. The joining
surfaces were modified by Ni/Al reactive multilayer deposition as an alternative approach to conventional diffusion bonding.
TiAl substrates were coated with alternated Ni and Al nanolayers. The nanolayers were deposited by dc magnetron sputtering
with 14 nm of period (bilayer thickness). Joining experiments were performed at 900 °C for 30 and 60 min with a pressure of
5 MPa. Cross sections of the joints were prepared for characterization of their interfaces by scanning electron microscopy
(SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), high resolution TEM (HRTEM),
energy dispersive x-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). Several intermetallic compounds form
at the interface, assuring the bonding of the TiAl. The interface can be divided into three distinct zones: zone 1 exhibits
elongated nanograins, very small equiaxed grains are observed in zone 2, while zone 3 has larger equiaxed grains. EBSD analysis
reveals that zone 1 corresponds to the intermetallic Al2NiTi and AlNiTi, and zones 2 and 3 to NiAl. 相似文献
58.
Marco Roberto Cavallari Vinicius Ramos Zanchin Mariana Pojar Antonio Carlos Seabra Marcelo de Assumpção Pereira-da-Silva Fernando Josepetti Fonseca Adnei Melges de Andrade 《Journal of Electronic Materials》2014,43(5):1317-1325
A low-cost patterning of electrodes was investigated looking forward to replacing conventional photolithography for the processing of low-operating voltage polymeric thin-film transistors. Hard silicon, etched by sulfur hexafluoride and oxygen gas mixture, and flexible polydimethylsiloxane imprinting molds were studied through atomic force microscopy (AFM) and field emission gun scanning electron microscopy. The higher the concentration of oxygen in reactive ion etching, the lower the etch rate, sidewall angle, and surface roughness. A concentration around 30 % at 100 mTorr, 65 W and 70 sccm was demonstrated as adequate for submicrometric channels, presenting a reduced etch rate of 176 nm/min. Imprinting with positive photoresist AZ1518 was compared to negative SU-8 2002 by optical microscopy and AFM. Conformal results were obtained only with the last resist by hot embossing at 120 °C and 1 kgf/cm2 for 2 min, followed by a 10 min post-baking at 100 °C. The patterning procedure was applied to define gold source and drain electrodes on oxide-covered substrates to produce bottom-gate bottom-contact transistors. Poly(3-hexylthiophene) (P3HT) devices were processed on high-κ titanium oxynitride (TiO x N y ) deposited by radiofrequency magnetron sputtering over indium tin oxide-covered glass to achieve low-voltage operation. Hole mobility on micrometric imprinted channels may approach amorphous silicon (~0.01 cm2/V s) and, since these devices operated at less than 5 V, they are not only suitable for electronic applications but also as sensors in aqueous media. 相似文献
59.
C. Alvarez-Ney J. Labarga M. Moratalla J. M. Castilla M. A. Ramos 《Journal of Low Temperature Physics》2017,187(1-2):182-191
The specific heat of toluene in glass and crystal states has been measured both at low temperatures down to 1.8 K (using the thermal relaxation method) and in a wide temperature range up to the liquid state (using a quasiadiabatic continuous method). Our measurements therefore extend earlier published data to much lower temperatures, thereby allowing to explore the low-temperature “glassy anomalies” in the case of toluene. Surprisingly, no indication of the existence of tunneling states is found, at least within the temperature range studied. At moderate temperatures, our data either for the glass or for the crystal show good agreement with those found in the literature. Also, we have been able to prepare bulk samples of toluene glass by only doping with 2% mol ethanol instead of with higher impurity doses used by other authors. 相似文献
60.