Search results for " Kinetics"
showing 10 items of 285 documents
High accuracy [sup 18]O(p,α)[sup 15]N reaction rate in the 8⋅10[sup 6]–5⋅10[sup 9] K temperature range
2011
The 18O(p,α)15N reaction is of great importance in several astrophysical scenarios, as it influences the production of key isotopes such as 19F, 18O and 15N. In this work, a high accuracy 18O(p,α)15N reaction rate is proposed, based on the simultaneous fit of direct measurements and of the results of a new Trojan Horse experiment. In particular, we have focused on the study of the broad 660 keV 1/2+ resonance. Since Γ∼100–300 keV, it strongly influences the nearly‐zero‐energy region of the cross section by means of the low‐energy tail of the resonant contribution and dominates the cross section at higher energies. Here we provide a factor of 2 larger reaction rate above T∼0.5 109 K based ov…
Bifunctional coordination polymers as efficient catalysts for carbon dioxide conversion
2019
AN ENZYME-ENHANCED EXTRACTION OF ANTHOCYANINS FROM RED CABBAGE AND THEIR THERMAL DEGRADATION KINETICS
2020
There is a great demand for developing efficient anthocyanins extraction related to each plant material. Conventional methods have been replaced by novel techniques, but they might remain attractive when combined with the latter. Anthocyanins extraction from fresh and dried red cabbage was investigated by maceration, ultrasonication, and with enzymes. Pre-treatments through drying determined an improved extraction with respect to fresh samples, freeze-drying emerging as the best method. Combined enzyme-assisted extraction with maceration resulted in higher yield by conducting several extractions (1078.8±12.5 mg/100 g DW). The kinetic studies revealed good stability of anthocyanins at 50 °C,…
Equilibrium and studies on sorption of heavy metals from solutions by algae
2013
Ball milling and AlB2 addition effects on the hydrogen sorption properties of the CaH2 + MgB2 system
2010
Among the borohydrides proposed for solid state hydrogen storage,Ca(BH4)2 is particularly interesting because of its favourable thermodynamics and relatively cheap price.Composite systems,whereother species are present in addition to the borohydride,show some advantages in hydrogen sorption properties with respect to the borohydrides alone,despite a reduction of the theoretical storage capacity. We have investigated the milling time influence on the sorption properties of the CaH2 +MgB2 system from which Ca(BH4)2 and MgH2 can be synthesized by hydrogen absorption process.Manometric and calorimetric measurements showed better kinetics forlong time milled samples.We found that the total subst…
DIMENSIONAL STABILITY OF REINFORCED MATRICES.
1983
Particulate fillers are often used to improve the dimensional stability of polymeric items obtained through processing techniques such as injection molding, deep drawing, hot stamping, etc. In these operations the material undergoes large multiaxial deformations which result in molecular orientation and remain as frozen-in stresses during cooling of the material. Once the formed objects are exposed to sufficiently high temperatures, various degrees of spring-back take place and subsequent changes in shape and dimension occur (1).
Hygrothermal ageing of reprocessed polylactide
2012
[EN] The influence of an accelerated hygrothermal ageing simulation test on a commercial PLA and its three subsequent mechanically-reprocessed materials was studied. The analysis was focused on the water diffusion kinetics and the physico-chemical changes induced by the hygrothermal degradation. Water diffusion proceeded faster than chain relaxation processes, as defined by a Case II absorption model. It was proved that the water diffusion rate decreased with subsequent reprocessing cycles and increased with higher hygrothermal ageing temperatures. Hydrolytic chain scission provoked significant molar mass decays and consequent general losses of thermal and mechanical performance. The rearra…
Valorization of rapeseed meal by solid state fermentation for an application in animal nutrition
2017
Solid state fermentation (SSF) is a biotechnological process particularly well adapted to the treatment of vegetable biomass. This technology adjustable to industrial scale, is adapted to current challenges in animal nutrition by developing fermented products in order to improve the quality of raw materials from a nutritional and functional point of view. The work presented in this thesis considers these issues using rapeseed meal from the oil crushing industry.A first screening study highlighted several fungal strains based on their growth performance and protein enrichment (total and digestible) of the substrate. Levels similar to those of soybean meal, the main protein source in animal n…
Modelagem da cinética de secagem de discos de maçã e abobrinha impregnadas a vácuo com antocianinas
2019
ABSTRACT: The aim of this research was to study the drying kinetics of apple and zucchini slices enriched with anthocyanins and to evaluate the influence of drying temperature on the anthocyanin content of apple and zucchini snacks. Apple (Granny Smith) and zucchini (Cucurbita pepo) slices were enriched with anthocyanins by vacuum impregnation with blueberry juice. Then, slices were dehydrated at 40, 50 and 60 ºC with 1.0 m/s air flow. Dehydrated samples were referred to as anthocyanin enriched snacks. Diffusion coefficient values improved by increasing the drying temperature, within the 2.81×10-10 to 5.78×10-10 m2/s range for apple slices and 2.02×10-10 to 3.99×10-10 m2/s for zucchini slic…
Kinetics of photochemical isomerization of TFA-Gly-ZΔPhe into TFA-Gly-EΔPhe
2017
The kinetics of photoisomerization of trifluoroacetyl-(Z)-dehydrophenylalanylglycine into trifluoroacetyl-(E)- dehydrophenylalanylglycine was studied in the hope that light-induced reaction could be useful as a means of preparation of the E-dehydropeptides. The obtained results indicate that if this reaction carried out under irradiation with light of wavelength 360 nm it is practically irreversible and gave nearly quantitatively pure Eisomer Significantly, expected cyclic side-products were not observed in the reaction mixture, thus proving the preparative potential of the elaborated procedure.