Rate Constants
Mostrando 13-24 de 1000 artigos, teses e dissertações.
-
13. The devitrification kinetics of transparent silica glass prepared by gel-casting method
ABSTRACT The kinetics of the crystallization of cristobalite in the amorphous silica glass were studied for samples prepared by gel-casting and sintering in air. Avrami and rate equations were used to calculate the rate constants and the activation energy. The results showed that the crystallization obeys the first order and occurs mainly on the surface with
Matéria (Rio J.). Publicado em: 20/05/2019
-
14. Kinetic parameters of lipid oxidation in third generation (3G) snacks and its influence on shelf-life
Abstract In food systems, lipid oxidation is one of the most important factors affecting food quality, nutrition, safety, color and consumer acceptance. The objective of this study was to determine the kinetic parameters of lipid oxidation and its influence in the shelf life of third generation (3G) snacks stored in three types of packaging (polyethylene, p
Food Sci. Technol. Publicado em: 07/01/2019
-
15. Kinetic parameters of lipid oxidation in third generation (3G) snacks and its influence on shelf-life
Abstract In food systems, lipid oxidation is one of the most important factors affecting food quality, nutrition, safety, color and consumer acceptance. The objective of this study was to determine the kinetic parameters of lipid oxidation and its influence in the shelf life of third generation (3G) snacks stored in three types of packaging (polyethylene, p
Food Sci. Technol. Publicado em: 20/12/2018
-
16. Predicting sugar content of candied watermelon rind during osmotic dehydration
Abstract Watermelon rind, comprising 35% of the fruit’s total mass, usually discarded due to its unappealing flavor and lack of sweetness. In this study, candied watermelon rind was prepared through osmotic dehydration at vacuum (VOD) and atmospheric pressure (OD). The effects of independent variables (sucrose concentration, immersion time and temperature
Food Sci. Technol. Publicado em: 13/12/2018
-
17. Effect of Blanching on Enzyme Activity and Bioactive Compounds of Blackberry
ABSTRACT The inactivation of peroxidase and polyphenol oxidase and the degradation of phenolic compounds, anthocyanins, and antioxidant activity in blackberry were investigated during blanching in water at 80-90 °C, and in steam, from 0 to 10 minutes. The enzyme kinetics indicated the presence of two isoenzymes with different thermal stability, following tw
Braz. arch. biol. technol.. Publicado em: 14/11/2018
-
18. KINETIC BEHAVIOR OF SOME AZO DYES DECOLORIZATION BY VARIATION OF ZINC OXIDE AND TITANIUM DIOXIDE CONCENTRATIONS
The decolorization of three monoazo dyes (acid orange 7, direct orange 34, and methyl orange), one diazo dye (direct yellow 86) and one tetraazo dye (direct red 80) were mediated by n-type semiconductors as ZnO and TiO2 under pseudo-first order conditions at 30 ºC. The decolorization rate constants of these azo dyes were determined, varying the semiconducto
Quím. Nova. Publicado em: 2018-03
-
19. Screening and Binding Analysis of Flavonoids with Alpha-Amylase Inhibitory Activity from Lotus Leaf
Lotus leaf is gaining growing popularity due to its various benefits and widely usage. In this paper, ten flavonoids in lotus leaf extract were analyzed by high performance liquid chromatography (HPLC). Centrifugal ultrafiltration combined liquid chromatography was used to screen alpha-amylase inhibitors from ten flavonoids mixture and the binding degrees ra
J. Braz. Chem. Soc.. Publicado em: 2018-03
-
20. ESTUDO CINÉTICO DE DECOMPOSIÇÃO TÉRMICA DE ESPUMAS RÍGIDAS DE POLIURETANO POR REDE NEURAL ARTIFICIAL
Kinetic models of solid thermal decomposition are traditionally used for individual fit of isothermal experimental data. However, this methodology presents unacceptable errors in some regions of the data. To solve this problem, a neural network was adopted in this work. The implemented algorithm uses the rate constants as predetermined weights between the in
Quím. Nova. Publicado em: 2017-10
-
21. The Use of the Liquid from Cashew Nut Shells as an Antioxidant in Biodiesel
The influence of cashew nutshell liquid (CNSL) in the oxidative stability of biodiesels prepared from oils of soy, corn, canola and sunflower was studied using the Rancimat method. The induction periods at 110 ºC, without and with the addition of CNSL at concentrations of 0.1, 0.5 and 1.0% m/m, were determined and clearly show an important increase in the o
J. Braz. Chem. Soc.. Publicado em: 2017-05
-
22. Ag Nanoparticles-Based Zinc Hydroxide-Layered Hybrids as Novel and Efficient Catalysts for Reduction of 4-Nitrophenol to 4-Aminophenol
Silver nanoparticles and zinc hydroxide-layered hybrid materials (AgNPs/ZHL) have been successfully developed as efficient catalysts for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride. A facile and rapid visible-light assisted green route was used for the deposition of silver nanoparticles (AgNPs) on the external surfac
J. Braz. Chem. Soc.. Publicado em: 2017-01
-
23. Fighting Collinearity in QSPR Equations for Solution Kinetics with the Monte Carlo Method and Total Weighting
A Monte Carlo method is used in addition to functional and individual weighting to overcome multicollinearity problems in multiple linear regression equations applied as quantitative-structure-property-relationships, allowing the estimation of correct coefficient confidence intervals. The method was applied to rate constants for the Menschutkin reaction betw
J. Braz. Chem. Soc.. Publicado em: 2016-11
-
24. Distribution of Xanthene Dyes in DPPC Vesicles: Rationally Accounting for Drug Partitioning Using a Membrane Model
The correct selection of a dye that has effective action as a photosensitizer is a primary concern for successful therapeutic outcomes. The effectiveness of the photodynamic agent is related to both the targeting of cell membranes and the photochemical yield of the chosen dye. The distributions of xanthene derivatives Eosin Y, Erythrosin B, and Rose Bengal B
J. Braz. Chem. Soc.. Publicado em: 2016-11