RESUMO
The density-functional theory (DFT) approximations that are the most accurate for the calculation of bandgap of bulk materials are hybrid functionals, such as HSE06, the modified Becke-Johnson (MBJ) potential, and the GLLB-SC potential. More recently, generalized gradient approximations (GGAs), such as HLE16, or meta-GGAs, such as (m)TASK, have also proven to be quite accurate for the bandgap. Here, the focus is on two-dimensional (2D) materials and the goal is to provide a broad overview of the performance of DFT functionals by considering a large test set of 298 2D systems. The present work is an extension of our recent studies [T. Rauch, M. A. L. Marques, and S. Botti, Phys. Rev. B 101, 245163 (2020); Patra et al., J. Phys. Chem. C 125, 11206 (2021)]. Due to the lack of experimental results for the bandgap of 2D systems, G0W0 results were taken as reference. It is shown that the GLLB-SC potential and mTASK functional provide the bandgaps that are the closest to G0W0. Following closely, the local MBJ potential has a pretty good accuracy that is similar to the accuracy of the more expensive hybrid functional HSE06.
RESUMO
This research was intended to investigate the structural feature, antioxidative activity and interaction with ß-lactoglobulin (ß-lg) of a polysaccharide (P) isolated from Borassus flabellifer fruit thru aqueous extraction, protein elimination and chromatographic techniques. Polysaccharide P (molecular weight: 21,000 g mol-1) was constituted of arabinose, galactose, glucose, and rhamnose in a 50:24:20:6 M ratio alongside 9% (w/w) galacturonic acid. It encompassed a petite backbone entailing galacturonopyranosyl and rhamnopyranosyl units substituted with sizable side chains comprising of arabinofuranosyl, galactopyranosyl and esterified coumaric acid (CA) residues. Various series of oligosaccharides including (i) Gal1,2,4-9Ac5-29, (ii) Ara2-3Ac6-8, (iii) Gal3Ara1-3Ac13-17, (iv) Gal4-6Ara2Ac18-24, (v) Gal6Ara1Ac22 and (vi) Gal1Ara2CA1Ac7 and Gal1Ara3CA1Ac9 epitomizing polysaccharide structure were generated and characterised. Fraction P exhibited dose-dependent antioxidant activity and possessed a strong ß-lactoglobulin binding capability. Accordingly, B. flabellifer fruit offers an antioxidative polysaccharide having novel structure that can associate with ß-lg and, hence, useful in formulating novel food possessing adjustable composition.