Rheological properties and gel strength of Phaseolus lunatus protein/carboxymethylated flamboyant gum systems

The rheological behaviour and gel strength of hydrocolloid mixture systems (HMSs) of carboxymethylated flamboyant gum (CFG) with protein hydrolysates (PHs) of Phaseolus lunatus were examined to evaluate the influence of the protein/polysaccharide ratio (2:1 and 3:1), pH (3 and 9) and concentration of solids, according to a 2³ factorial design. The protein concentrate of P. lunatus was hydrolysed with pepsin–pancreatin enzymes. The flow curve results were fitted to the Ostwald–de Waele model. The flow behaviour index (0.66–0.78) for all conditions studied was indicative of the shear‐thinning behaviour. For the HMS, the consistency index (k) values ranged from 0.4 Pa sⁿ to 1.2 Pa sⁿ. The analyses of variance showed that the ratio of PH/CFG and pH were the main variables that had significant effect on k values (P < 0.05). Only PH system presented a weak gel‐like viscoelastic behaviour. Both functional properties were affected by the protein degree of hydrolysis (DH).     

Ethyl group as matrix modifier and inducer of ordered domains in hybrid xerogels synthesised in acidic media using ethyltriethoxysilane (ETEOS) and tetraethoxysilane (TEOS) as precursors

Hybrid silica xerogels favourably combine the properties of organic and inorganic components in one material; consequently these materials are useful for multiple applications. The versatility and mild synthetic conditions provided by the sol-gel process are ideal for the synthesis of hybrid materials. The specific aims of this study were to synthesise hybrid xerogels in acidic media using tetraethoxysilane (TEOS) and ethyltriethoxysilane (ETEOS) as silica precursors, and to assess the role of the ethyl group as a matrix modifier and inducer of ordered domains in xerogels. All xerogels were synthesised at pH 4.5, at 60 °C, with 1:4.75:5.5 TEOS:EtOH:H₂O molar ratio. Gelation time exponentially increased with the ETEOS molar ratio. Incorporation of the ethyl groups into the structure of xerogels reduced cross-linking, increased the average siloxane bond length, and promoted the formation of ordered domains. As a result, a transition from Qⁿ to Tⁿ signals detected in the ²⁹Si NMR spectra, the Si–O structural band in the FTIR spectra shifted to lower wavelength, and a new peak in the XRD pattern at 2θ < 10° appeared in the XRD patterns. Mass spectroscopy detected fragments with high numbers of silicon atoms and a polymeric distribution.     

Neuro-semantic prediction of user decisions to contribute content to online social networks

Neural Computing and Applications - Understanding at microscopic level the generation of contents in an online social network (OSN) is highly desirable for an improved management of the OSN and the...     

Effect of polar solvents on the crystalline phase of polyamides

We investigate the effect of absorption of polar solvents (water and ethanol) on the structure of amorphous and semi-crystalline copolyamides containing aromatic entities. Different length scales of structural organisation are probed using a combination of Small angle X-ray scattering and neutron/X-rays diffraction. Crystallisation in the presence of solvent, characterised by very slow kinetics, is observed in the originally amorphous material, as a combined effect of a rearrangement of the hydrogen-bond distribution and plasticization. The steady-state crystalline structure is reached on a timescale much longer than the absorption kinetics, and is similar but not identical to that of processed semi-crystalline materials. In semi-crystalline polyamides water absorption induces a swelling of the spacing of the lamellar stacking but also modifications of the unit cell structure, which suggest a moderate but significant rearrangement of the hydrogen bond structure in the crystalline phase.     

The Quality,Stability, and Bioactive Compound Composition of Virgin and Refined Organic Grape Seed Oil

Samples of virgin and refined organic grape seed oil were studied for their physicochemical quality, oxidative stability, and the bioactive compounds they contained. All of the samples were within the limits established by the Codex Alimentarius with regard to their quality parameters. Lutein, zeaxanthin, β‐carotene, α‐tocopherol, and catechin were the bioactive compounds analyzed, and the virgin oil afforded more significant results. No measurable amounts of zeaxanthin and β‐carotene were observed in the refined oil, most likely due to the refining process that was carried out at high temperatures. The oxidative stability index decreased with increasing temperature, whereas the air flow had no effect on the stability index. The optimal parameters for the oxidative stability are 80 °C and a flow rate of 15 L h^?1, and the virgin oil sample showed the best oxidative stability, possibly because it was not subjected to any treatment after extraction. The results from this study suggest that it would be preferable to consume virgin instead of refined grape oil because it is a better source of bioactive compounds and has a higher stability when heated.     

Influence of the amorphous phase molecular mobility on impact and tensile properties of polyamide 6,6

In this work, the relationship between molecular mobility of polyamide 6,6 amorphous phase and mechanical properties is studied. PA66 formulations having different glass transition temperatures (T_g) obtained by additivation, chemical modification of the polyamide chains, and/or water conditioning at different hygrometry levels, are considered. The main emphasis is put on the impact strength, as measured by instrumented Charpy impact tests over a broad temperature range. It is observed that the brittle‐tough transition temperature T_B/T is closely correlated with the T_g of the samples rather than to the β secondary relaxation. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43457.