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[en] Protein hydrolysates from angelwing clam were obtained by enzymatic hydrolysis using bromelain. The bitterness of hydrolysates was evaluated based on the degree hydrolysis (DH), sensory analysis, molecular weight distribution and functional group. By using 3 % of enzyme substrate ratio bromelain resulted in high DH value at 12.57 % when angelwing clam was hydrolysed for 2 hours. Sensory analysis showed that angelwing hydrolysate was bitter. Angelwing hydrolysate had molecular weight below 50 kDa. The lower molecular weight indicated that the protein has been degraded into smaller peptide chains which contribute to bitter taste. Moreover, the high peak of amine group in angelwing hydrolysate (3385.6 cm-1) suggested that bitterness exists. Angelwing hydrolysate had higher protein content, lower fat content and had good water holding capacity than the flesh. This result suggested that angelwing hydrolysate could be useful as food ingredient even though bitter taste developed after the hydrolysis. Thus, debittering should be considered in order to pave the way for full utilization of angelwing clam hydrolysate as a food ingredient. (author)
[en] Phoenix tree (Firmiana simplex) seed oil is a novel oil which is rich in sterculic acid. Sterculic acid, a cyclopropene fatty acid, can be used as the inhibitor of the stearoyl-CoA desaturase system and mammary carcinomas growth. In this work, Lipozyme TLIM-catalyzed hydrolysis of the novel Phoenix tree seed oil was used to prepare sterculic acid. High temperature GC-FID and the degree of hydrolysis (DH) were used to monitor the reaction progress. Effects of reaction variables on the hydrolysis were evaluated and optimized using response surface methodology. Results showed that sterculic acid can be successfully prepared from the novel seed oil, and the effect of reaction variables on the hydrolysis decreased in the order of reaction time > enzyme load > temperature. A high yield of fatty acids (DH, 98.2±0.8%) can be obtained under optimized conditions (45 ºC, mass ratio of water to oil 10:1, enzyme load 10%, and 18 h). The Arrhenius equation for the hydrolysis was LnV0 = 9.12 − 4721/T. The activation energy was 39.25KJ/mol. The kinetic values for Vmax, K/m were 0.232mol/(L∙min) and 0.084 mol/L, respectively.
[es]El aceite de semilla del árbol fenix (Firmiana simplex) es un nuevo tipo de aceite rico en ácido estercúlico. Este es un ácido graso ciclopropeno, que se puede utilizar como inhibidor del sistema de estearoyl-CoA desaturasa y del crecimiento de los carcinomas mamarios. En este trabajo, se utilizó la hidrólisis catalizada por Lipozyme TLIM del nuevo aceite de semilla de árbol fenix para preparar ácido estercúlico. Se utilizaron GC-FID a alta temperatura y el grado de hidrólisis (DH) para monitorizar el progreso de la reacción. Los efectos de las variables de reacción de hidrólisis se evaluaron y optimizaron utilizando la metodología de superficie de respuesta. Los resultados mostraron que el ácido estercúlico puede prepararse con éxito a partir del nuevo aceite de semilla, y el efecto de las variables de reacción en la hidrólisis disminuyó en el orden de tiempo de reacción> carga enzimática> temperatura. Se pueden obtener altos rendimientos de ácidos grasos (DH, 98,2 ± 0,8%) en condiciones optimizadas (45 ºC, relación masa de agua a aceite 10: 1, carga enzimática 10% y 18 h). La ecuación de Arrhenius para la hidrólisis fue LnV0 = 9,12 − 4721/T. La energía de activación fue 39,25KJ/mol. Los valores cinéticos de Vmax, K/m fueron 0,232 mol/(L ∙ min) y 0,084 mol/L, respectivamente.
[en] Current literature suggests uncertainty about the numerical values of the hydrolysis constants for tetravalent plutonium. This letter uses recent data to propose that newer methods for estimating the hydrolysis constants are not necessarily more accurate than the traditional methods. (author)
[en] A hydrolysis column, used to hydrolyze uranium hexafluoride gas with water in an ammonium diuranate conversion process, which includes a pipe having a water inlet, a connector inserted in the pipe intermediate its length, and a gas nozzle connected to the connector to feed uranium hexafluoride gas into the water. Since the uranium hexafluoride gas will freeze at 1470F, the gas nozzle is heated by steam which flows through internal passageways, thus imparting sufficient heat to the nozzle which then acts as a heat sink to maintain the gas in a fluid state. The gas-water mixture is then discharged through the pipe outlet to the next step in the process
[en] The use of microbial cellulolytic enzymes is the most efficient process to liberate glucose from cellulose in biomass without the formation of fermentation inhibitors. A combination of pretreatment technologies is an alternative way to increase the access of enzymes to cellulose, and consequently, the conversion yield. In this way, the present study reports on the enzymatic hydrolysis of SCB submitted to three kinds of pretreatment: electron beam processing (EBP), and EBP followed by hydrothermal (TH) and diluted acid (AH) treatment. SCB samples were irradiated using a radiation dynamics electron beam accelerator, and then submitted to thermal and acid (0.1% sulfuric acid) hydrolysis for 40 and 60 min at 180 °C. These samples were submitted to enzymatic hydrolysis (EH) using commercial preparations, including Celluclast 1.5 L and beta-glycosidase. The addition of diluted acid improved TH treatment allowing for a shorter application time. EBP with 50 kGy increased the enzymatic hydrolysis yield of cellulose by 20% after TH and 30% after AH. - Highlights: ► We study the enzymatic hydrolysis of cellulose and hemicellulose in sugarcane bagasse. ► We study the combination of three pretreatments: electron beam processing, EBP followed by hydrothermal and by diluted acid treatment. ► The electron beam processing increased the enzymatic hydrolysis from 8% to 15% with 20 kGy. ► The enzymes used were commercial preparations, as Celluclast 1.5 L and β-glycosidase. ► The EBP with 50 kGy increased on 20% the yield of EH of cellulose after TH and 30% after AH.
[en] Six discrete formulas are used to estimate the equilibrium constant of the first hydrolysis reaction of tetravalent plutonium. They apply the pH, the oxidation number, one equilibrium constant, and fractions of two of the plutonium oxidation states. The new formulas are not restricted to the equilibrium condition. (author)
[en] A new method for estimating the numerical value of the first hydrolysis constant of tetravalent plutonium is illustrated by examples. It uses the pH and the equilibrium fractions of two of the Pu oxidation states. They are substituted into one or more of a choice of formulas that render explicit estimates of the hydrolysis constant. (author)
[en] There is little study on the hydrolysis reactions of Nheteroarylimidazole derivatives in comparison with those of N-acylimidazoles. Some years ago, we reported the hydrolysis reactions of N-heteroaryl-2-phenylimidazoles, Nfuroyl- 2-phenylimidazole and N-thenoyl-2-phenylimidazole. In the hydrolysis reactions of these compounds, we found a change of the rate dertermining step in acidic regions. These results are very unique even though the feature of hydrolysis reactivity of N-acylimidazole derivatives depends on the structure of N-acylimidazole. But, when one changes the acyl group with the heteroaryl group to the benzoyl group having same leaving group, the pH rate profile for the hydrolysis reaction of N-benzoyl-2-phenylimidazole observed to be related with the diprotonated species of the substrate in acidic region. Finally, in this study, we have found that the rate accelerating effect by the substituent, NO2 group in the leaving group is small. The large kOH value in OH'- catalyzed hydrolysis reaction should be explained that the resonance interaction of the leaving group itself is more important than that between N-1 atom of the imidazole and the carbonyl carbon.
[en] In this work, we tested the applicability of several methyl substituted benzyl groups as an alternative to the methyl group for the protection of the hydroxyl groups in the nucleophilic aromatic radiofluorination. As a model synthesis, the no-carrier-added (n.c.a.) preparation of 2-[18F]fluoro-3-hydroxy-6-methylpyridine from O-protected 3-hydroxy-6-methyl-2-nitropyridine was chosen. Conditions for acidolytic and hydrogenolytic cleavage of heteroaryl esters were studied. Among various protecting groups tested, 4-methylbenzyl and 2,4-dimethylbenzyl groups proved to be the best by resulting in about 70% yields of [18F]-labelled product after hydrolysis with 32% HCl at 120 deg C for 10 min. Furthermore, 4-methylbenzyl ester cleaved readily under catalytic transfer hydrogenation condition using ammonium formate and 10% Pd/C in boiling methanol to give 2-[18F]fluoro-3-hydroxy-6-methylpyridine in radiochemical yield of 75% within a reaction time of 10 min. Conditions for the cleavage of both 4-methylbenzyl and 2,4-dimethylbenzyl esters are well suited for the implementation into an automated synthesis module. (author)
[en] A neck-linker swing model has been proposed in this work to investigate the mechanochemical coupling of kinesin. The difference between force-velocity curves given by force clamp and fixed trap respectively has been satisfactorily interpreted by this model. The study implies that ADP releasing and ATP hydrolysis are much less force-dependent in force clamp experiments than that in fixed trap experiments in the regime of moderate loading force, which might be a consequence of the delayed response of servo system in force clamp experiments. (interdisciplinary physics and related areas of science and technology)