899 resultados para pH of colloidal suspension
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Studies for the food development of formulations for pets, look for key components to maintaining healthy way of life and safety of products, including these, elements capable of preventing the risk of certain metabolic disorders associated with diet. Feline urinarytract disorders, highlights the urolithiasis, have high incidence in clinical series. Studies linking dietary factors such as ingredients, digestibility and chemical composition, changing the volume, density and pH of urine and consequent induction training for urolithiasis. A highly significant correlation between the mineral composition of the diet and urine pH of cats began to be studied, using the association between the cation-anion balance of the diet (DCAB) and regulation of acid-base balance of the body. The DCAB can be defined as the difference between the total fixed anions and cations present in the diet, important tool for estimating the urinary pH and to determine the range of pH that favors the food used, thereby linking the trigger and the prevention of struvite and calcium oxalate urolithiasis in the urinary tract of cats. Thus, this review aims to clarify the effects of the nutritional composition of diet on urine pH in cats.
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The aim of this study was to investigate the effects of some acidic drinks on dentin erosion, using methods of surface profile (SP) analysis and energy-dispersive X-ray fluorescence spectrometry (EDXRF). One hundred standardized dentin slabs obtained from bovine incisor roots were used. Dentin slabs measuring 5x5 mm were ground flat, polished and half of each specimen surface was protected with nail polish. For 60 min, the dentin surfaces were immersed in 50 mL of 5 different drinks (Gatorade®, Del Valle Mais orange juice®, Coca-Cola®, Red Bull® and white wine), 20 blocks in each drink. The pH of each beverage was measured. After the erosive challenge, the nail polish was removed and SP was analyzed. The mineral concentration of dentin surfaces was determined by means of EDXRF. Data were analyzed statistically by ANOVA and Tukey's test (α=0.05). SP analysis showed that Red-Bull had the highest erosive potential (p<0.05). EDXRF results exhibited a decrease in phosphate in the groups immersed in Red-Bull, orange juice and white wine (p<0.05), and no significant difference in calcium content between the reference surface and eroded surface. In conclusion, this study demonstrated that all studied beverages promoted erosion on root dentin and Red Bull had the highest erosive potential. There was no correlation between pH of beverages and their erosive potential and only the P content changed after erosive challenge.
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The physiological state of yeast cells changes during culture growth as a consequence of environmental changes (nutrient limitations, pH and metabolic products). Cultures that grow exponentially are heterogeneous cell populations made up of cells regulated by different metabolic and/or genetic control systems. The strain of baker's yeast selected by plating commercial compressed yeast was used for the production of glycerol-3- phosphate dehydrogenase. Glycerol-3-phosphate dehydrogenase (GPD) has been widely used in the enzyme assays with diverse compounds of industrial interest, such as glycerol or glycerol phosphate, as well as a number of important bioanalytical applications. Each cell state determines the level of key enzymes (genetic control), fluxes through metabolic pathways (metabolic control), cell morphology and size. The present study was carried out to determine the effects of environmental conditions and carbon source on GPD production from baker's yeast. Glucose, glycerol, galactose and ethanol were used as carbon sources. Glycerol and ethanol assimilations required agitation, which was dependent on the medium volume in the fermentation flask for the greatest accumulation of intracellular GPD. Enzyme synthesis was also affected by the initial pH of the medium and inoculum size. The fermentation time required for a high level of enzyme formation decreased with the inoculum size. The greatest amount of enzyme (0.45 U/ml) was obtained with an initial pH of 4.5 in the medium containing ethanol or glycerol. The final pH was maintained in YP-ethanol, but in the YP-glycerol the final pH increased to 6.9 during growth.
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Since little information is available regarding cellular antigen mapping and the involvement of non-neuronal cells in the pathogenesis of bovine herpesvirus type 5 (BHV-5) infection, it were determined the BHV-5 distribution, the astrocytic reactivity, the involvement of lymphocytes and the presence of matrix metalloproteinase (MMP)-9 in the brain of rabbits experimentally infected with BHV-5. Twelve New Zealand rabbits that were seronegative for BHV-5 were used for virus inoculation, and five rabbits were used as mock-infected controls. The rabbits were kept in separate areas and were inoculated intranasally with 500 μl of virus suspension (EVI 88 Brazilian isolate) into each nostril (virus titer, 107.5 TCID50). Control rabbits were inoculated with the same volume of minimum essential medium. Five days before virus inoculation, the rabbits were submitted to daily administration of dexamethasone. After virus inoculation, the rabbits were monitored clinically on a daily basis. Seven rabbits showed respiratory symptoms and four animals exhibited neurological symptoms. Tissue sections were collected for histological examination and immunohistochemistry to examine BHV-5 antigens, astrocytes, T and B lymphocytes and MMP-9. By means of immunohistochemical and PCR methods, BHV-5 was detected in the entire brain of the animals which presented with neurological symptoms, especially in the trigeminal ganglion and cerebral cortices. Furthermore, BHV-5 antigens were detected in neurons and/or other non-neural cells. In addition to the neurons, most infiltrating CD3 T lymphocytes observed in these areas were positive for MMP-9 and also for BHV-5 antigen. These infected cells might contribute to the spread of the virus to the rabbit brain along the trigeminal ganglia and olfactory nerve pathways. © 2013 Elsevier Ltd.
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This study evaluated the physicochemical changes in Nile tilapia (n = 82, 373.71 ± 61.91 g) refrigerated for up to 92 h and in the frozen fillets. The tilapias were captured with nets, slaughtered by ice and water shock (1:1) in a temperature of approximately 2°C for 30 min, and stored refrigerated at 4°C in polystyrene boxes containing ice. The fish were filleted, and filets were weighed and frozen. The drip loss and protein were determined after 23 days of frozen storage. After 4 h of storage, all fish were in full rigor mortis. The pH of the muscles decreased for up to 45 h of the storage period. The fillets obtained from tilapia stored for more than 72 h lost more weight and protein. Thus, the filleting or processing of tilapia should be done before 72 h of cold storage, since deterioration of the fish starts to occur after this period. Copyright © Taylor & Francis Group, LLC.
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Natural rubber/gold nanoparticles membranes (NR/Au) were studied by ultrasensitive detection and chemical analysis through surface-enhanced Raman scattering and surface-enhanced resonance Raman scattering in our previous work (Cabrera et al., J. Raman Spectrosc. 2012, 43, 474). This article describes the studies of thermal stability and mechanical properties of SERS-active substrate sensors. The composites were prepared using NR membranes obtained by casting the latex solution as an active support (reducing/establishing agents) for the incorporation of colloidal gold nanoparticles (AuNPs). The nanoparticles were synthesized by in situ reduction at different times. The characterization of these sensors was carried out by thermogravimetry, differential scanning calorimetry, scanning electron microscopy (SEM) microscopy, and tensile tests. It is suggested an influence of nanoparticles reduction time on the thermal degradation of NR. There is an increase in thermal stability without changing the chemical properties of the polymer. For the mechanical properties, the tensile rupture was enhanced with the increase in the amount of nanoparticles incorporated in the material. © 2013 Wiley Periodicals, Inc.
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An Advanced Oxidation Process (AOPs) was carried out in this study with the use of immobilized ZnO and solar/UV as an energy source to degrade dairy wastewater. The semibatch reactor system consisted of metal plate of 800 × 250 mm and a glass tank. The reaction time was of 3 h for 3 L of dairy wastewater. Experiments were performed based on a surface response methodology in order to optimize the photocatalytic process. Degradation was measured in percentage terms by total organic carbon (TOC). The entry variables were ZnO coating thickness and pH, using three levels of each variable. The optimized results showed a TOC degradation of 31.7%. Optimal parameters were metal-plate coating of 100 m of ZnO and pH of 8.0. Since solar/UV is a constant and free energy source in most tropical countries, this process tends to suggest an interesting contribution in dairy wastewater treatment, especially as a pretreatment and the optimal conditions to guarantee a better efficiency of the process. © 2013 Gisella R. Lamas Samanamud et al.
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Pós-graduação em Engenharia e Ciência de Alimentos - IBILCE
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Agronomia (Energia na Agricultura) - FCA
Crescimento de fibras de zircônia preparadas pela rota sol-gel a partir de moldes de cristal líquido
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)