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91.
Joselisse Soares de Carvaiho Santos Marcia Maria Lima Duarte Eduardo Lins de Barros Neto 《化学与化工:英文版》2014,(5):535-543
Polymers are high molecular weight molecules that provide high viscosity at low concentrations to the media they are inserted. In the oil industry, they are used for enhanced oil recovery and for drilling fluids, where its viscosity is an important factor for a greater efficiency. From all the polymers used by industry, the polyacrylamide and the biopolymer xantham gum are those, which appear significantly in those applications. Taking that into consideration, this work intends to study the effects of the physical, chemical and structural parameters of those polymers in their rheological behaviour, by varying their concentrations from 400 ppm to 2,000 ppm and their temperatures from 298 K to 328 K, which are values similar to those found in the field. For that, a Brookfield Viscometer-Brookfield Engineering Labs rheometer was used. The results acquired showed that the increase on the polyacrylamides ionicity generates and increase on the medium viscosity. For the temperature, its increase causes a reduction of viscosity for the low ionicity polyacrylamides, while increases the viscosity for the high ionicity ones. In the comparative study between xantham gum and polyacrylamides, it was possible to notice that, even though the biopolymer is more complex, its viscosity still is lower when compared to the polyacrylamides. 相似文献
92.
Juliana Alvarenga Alves Luiz Carlos de Oliveira Lima Disney Ribeiro Dias Cleiton Antônio Nunes Rosane Freitas Schwan 《International Journal of Food Science & Technology》2010,45(11):2358-2365
The aim of this study was to evaluate the contribution of yeast to the volatile profile of beverages obtained by the fermentation of lychee must through inoculated (Saccharomyces cerevisiae strains UFLA CA116 , UFLA CA1183 and UFLA CA1174 ) and spontaneous fermentation. Higher alcohols and esters were the primary volatiles detected by SPME/GC–MS. A Principal Component Analysis indicated similarities between UFLA CA116 and UFLA CA1183 and between UFLA CA1174 and spontaneous fermentation. Changing the yeast strain used in the fermentation process has the potential to modulate the volatile profile of fermented beverages. The beverage produced by the inoculation of yeast CA1183 showed the most complex aroma profile compared to the other beverages. 相似文献
93.
F.S. Lima E.S. Ribeiro R.S. Bisinotto L.F. Greco N. Martinez M. Amstalden W.W. Thatcher J.E.P. Santos 《Journal of dairy science》2013
Objectives were to determine the effects of GnRH at the initiation of the 5-d timed artificial insemination (AI) program combined with 2 injections of PGF2α on ovarian responses and pregnancy per AI (P/AI) in dairy heifers, and the role of progesterone concentrations on LH release and ovulation in response to GnRH. In study 1, heifers received a controlled internal drug release (CIDR) insert containing 1.38 g of progesterone on d 0, an injection of 25 mg of PGF2α and CIDR removal on d 5, and an injection of 100 μg GnRH concurrently with AI on d 8. Heifers were assigned to receive no additional treatment (control; n = 559) or an injection of GnRH on d 0 and a second injection of PGF2α on d 6 (G2P; n = 547). In study 2, all heifers were treated as described for the control in study 1, and were allocated to receive no additional treatment (control; n = 723), an injection of PGF2α on d 6 (NG2P; n = 703), or an injection of GnRH on d 0 and an injection of PGF2α on d 6 (G2P; n = 718). In study 3, heifers received a CIDR on d 7 after ovulation and were assigned randomly to a low-progesterone (LP; n = 6) treatment in which 2 injections of 25 mg of PGF2α each were administered 12 h apart, on d 7 and 7.5 after ovulation, or to a high-progesterone (HP; n = 12) treatment in which no PGF2α was administered. On d 8, heifers received 100 μg of GnRH and blood was sampled at every 15 min from −30 to 180 min relative to the GnRH for assessment of LH concentrations. Additionally, 94 heifers were assigned to LP or HP and ovulation in response to GnRH was evaluated. In study 1, P/AI was greater for G2P than for the control on d 32 (59.4 vs. 53.5%) and 60 after AI (56.6 vs. 51.3%). In study 2, administration of GnRH on d 0 increased the proportion of heifers with a new corpus luteum on d 5 (control = 21.9 vs. NG2P = 20.1 vs. G2P = 34.4%). Administration of a second PGF2α increased the proportion of heifers with progesterone <0.5 ng/mL at AI (control = 83.1 vs. NG2P = 93.0 and G2P = 87.2%). Pregnancy per AI was greater for G2P than for control and NG2P on d 32 (control = 52.9 vs. NG2P = 55.0 vs. G2P = 61.7%) and 60 (control = 49.0 vs. NG2P = 51.6 vs. G2P = 59.1%). In study 3, HP attenuated LH release and reduced ovulation (19.0 vs. 48.4%) in response to GnRH compared with LP. Combining GnRH and 2 doses of PGF2α in the 5-d timed AI protocol improved follicle turnover, luteolysis, and P/AI in heifers. Elevated concentrations of progesterone suppressed LH release and are linked with the low ovulatory response to the initial GnRH treatment of the protocol. 相似文献
94.
Demétrius Paiva Arçari Juliana Carvalho Santos Alessandra Gambero Lucio Fábio Caldas Ferraz Marcelo Lima Ribeiro 《Molecular nutrition & food research》2013,57(10):1882-1885
The aim of this study was to evaluate the effects of yerba maté (YM) extract on the phosphatidylinositol 3‐kinase (PI3K)‐AKT signaling pathway in vivo. The mice were introduced to either standard‐ or high‐fat diet (HFD). After 8 weeks on an HFD, mice were randomly assigned to one of the two treatment conditions, water or yerba maté extract at 1.0 g/kg. After treatment, glucose blood level and hepatic insulin response were evaluated. Liver tissue was examined to determine the mRNA levels using the PI3K‐AKT PCR array. The nuclear translocation of forkhead box O1 (FOXO1) was determined by an electrophoretic mobility‐shift assay. Our data demonstrated that yerba maté extract significantly decreased the final body weight, glucose blood levels, and insulin resistance of mice. Molecular analysis demonstrated that an HFD downregulated Akt2, Irs1, Irs2, Pi3kca, Pi3kcg, and Pdk1; after yerba maté treatment, the levels of those genes returned to baseline. In addition, an HFD upregulated Pepck and G6pc and increased FOXO1 nuclear translocation. The intervention downregulated these genes by decreasing FOXO1 nuclear translocation. The results obtained demonstrate for the first time the specific action of yerba maté on the PI3K‐AKT pathway, which contributed to the observed improvement in hepatic insulin signaling. 相似文献
95.
Disterfano Lima Martins Barbosa Jerson Rogerio Pinheiro Vaz Daborah Aline Tavares Dias do Rio Vaz Sivio Wesley Oliveira Figueiredo Marcelo Oliveira da Silva Andre Luiz Amarante Mesquita Claudio JoseCavalcante Blanco 《能源与动力工程:英文版》2013,(8):1472-1477
The use of diffusers around the horizontal-axis wind turbines has been widely studied since the diffuser improves the power coefficient of the turbine and it is often called DAWTs (diffuser augmented wind turbines).Turbines using diffuser are called DWATs (Diffuser Augmented Turbines),and have efficiency bigger than the Betz limit (maximum energy flow extracted = 59.26%). Thus, this study presents a mathematical model describing the behavior of the velocity profile internally to a diffuser according to the characteristics of flow and geometry of a conical diffuser. The results are compared with experimental data and show good agreement. 相似文献
96.
Effect of the Y2O3–ZrO2 support composition on nickel catalyst evaluated in dry reforming of methane
Nickel catalysts with a load of 5 wt.% Ni, supported on pure ZrO2 and ZrO2 stabilized with 4 mol%, 8 mol% and 12 mol% of Y2O3, were prepared by the polymerization method. The samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction with hydrogen (TPR-H2), specific surface area (BET) and electronic paramagnetic resonance (EPR) and tested as catalysts for carbon dioxide reforming of methane. The XRD patterns showed the presence of the oxide precursor (NiO) and the tetragonal phase of a Y2O3–ZrO2 solid solution. According to the TPR-H2 analysis, the reduction of various NiO species was influenced by the composition of the support. Catalytic tests were conducted at 800 °C for 6 h, and the composition of the gaseous products and the catalytic conversion rate depended on the composition of the Y2O3–ZrO2 solid solution and its influence on the supported NiO species. A direct relation was observed between the variation in the support, the nickel species supported on it and the performance in the catalytic tests. 相似文献
97.
Mayra A. D. Saleh Renato C. F. Neves Paula M. Moraes Paula M. Lima Felipe A. dos Santos Fábio A. Silva Pedro M. Padilha 《Sensing and Instrumentation for Food Quality and Safety》2009,3(2):108-113
This paper proposes a method to determine iron in samples of fish feed and feces using ultrasound in the extraction of the
analyte and in subsequent quantification by flame atomic absorption spectrometry. Using HCl 0.10 mol L−1 as the extraction solution, the optimal conditions of extraction were found to be: granulometry of the sample <60 μm; a sonication
time of five cycles of 10 s and sonication power of 136 W. The method was applied in studies of the availability of iron in
four food sources used in the diet of Nile Tilapia. The results obtained with the proposed extraction method allowed us to
calculate the coefficients of apparent digestibility of iron in the food sources, which was not possible when using results
obtained from samples mineralized by acid digestion. 相似文献
98.
Mary C.F. Alves Severino J.G. Lima José W.M. Espinosa Luiz E.B. Soledade Iêda M.G. Santos 《Materials Letters》2009,63(1):118-120
Strontium stannate (SrSnO3), a perovskite material, was synthesized by the polymeric precursor method, with different routes to eliminate organic matter. The utilization of pure oxygen for the elimination of organic matter changed the Raman spectra, especially in the low frequency region. Some peaks, which were previously assigned to the perovskite phase, were not noticed when the carbonate amount was lower. On the other hand, the profile of the IR spectra and XRD patterns did not change. These results suggest that carbonate may be present inside the perovskite lattice. 相似文献
99.
Rogério Cezar de Cerqueira Leite Manoel Regis Lima Verde Leal Luís Augusto Barbosa Cortez W. Michael Griffin Mirna Ivonne Gaya Scandiffio 《Energy》2009
Increasing use of petroleum, coupled with concern for global warming, demands the development and institution of CO2 reducing, non-fossil fuel-based alternative energy-generating strategies. Ethanol is a potential alternative, particularly when produced in a sustainable way as is envisioned for sugarcane in Brazil. We consider the expansion of sugarcane-derived ethanol to displace 5% of projected gasoline use worldwide in 2025. With existing technology, 21 million hectares of land will be required to produce the necessary ethanol. This is less than 7% of current Brazilian agricultural land and equivalent to current soybean land use. New production lands come from pasture made available through improving pasture management in the cattle industry. With the continued introduction of new cane varieties (annual yield increases of about 1.6%) and new ethanol production technologies, namely the hydrolysis of bagasse to sugars for ethanol production and sugarcane trash collection providing renewable process energy production, this could reduce these modest land requirements by 29–38%. 相似文献
100.
Rogério Fernandes Brito Solidônio Rodrigues de Carvalho Sandro Metrevelle Marcondes de Lima e Silva João Roberto Ferreira 《International Communications in Heat and Mass Transfer》2009
This work studies the heat influence in cutting tools considering the variation of the coating thickness and the heat flux. K10 and diamond tools substrate with TiN and Al2O3 coatings were used. The numerical methodology utilizes the ANSYS® CFX software. Boundary conditions and constant thermo physical properties of the solids involved in the numerical analysis are known. To validate the proposed methodology an experiment is used. The TiN and Al2O3 coatings did not show satisfying results during a continuous cutting process. It showed a slight reduction in the heat flux for the 10 (µm) TiN and Al2O3 coatings. 相似文献