Betalain and phenolic compositions of four beetroot (Beta vulgaris) cultivars

Four cultivars of red beetroot (Beta vulgaris) were evaluated with respect to their betalain and phenolic contents. The compounds were analysed using HPLC and identified by HPLC-DAD, HPLC-ESI-MS and NMR techniques. Betalains (vulgaxanthins I and II, betanin and isobetanin) and phenolics [5,5',6,6'-tetrahydroxy-3,3'-biindolyl, feruloylglucose and #-D-fructofuranosyl-!-D-(6-O-(E)-feruloylglucopyranoside)] were determined in different parts of the root; betalains were analysed separately in the water extract and phenolics in the fractionated 80% aqueous methanol extract (betalain-free water fraction). In each cultivar, both betanin and isobetanin were found in greater amounts in the peel than in the flesh. A similar trend was not observed in the distribution of vulgaxanthins. The three studied phenolics appeared in all root parts of the beetroot cultivars with the flesh generally containing the least content. Additionally, two phenolic amides (N-trans-feruloyltyramine and N-trans-feruloylhomovanillylamine) and four flavonoids (betagarin, betavulgarin, cochliophilin A and dihydroisorhamnetin) were detected in the fractionated 80% aqueous methanol peel extracts (acetonitrile fraction) of beetroot.     

Comparability and reliability of different techniques for the determination of phenolic compounds in virgin olive oil

Phenolic compounds represent a unique and functional part of the polar fraction of virgin olive oils. Many different approaches for the analysis of these compounds have been published, which has led to ambiguous results that are difficult to compare. In order to explain the controversial data reported in the literature, extraction techniques (solid‐phase extraction, SPE, and liquid‐liquid extraction, LLE), methods of analysis (HPLC and colorimetric assay) and quantification methods have been re‐investigated with genuine olive oil phenols. The optimized LLE system led to high recovery of the nine major olive oil phenolics (93%) and, in addition, was at least as good as the SPE technique in view of costs, solvent and sample consumption, and analysis time. SPE was shown to be problematic because of the selectivity towards the individual phenolics, particularly the aglycone‐type ones. The proposed LLE/HPLC method was compared with the traditional colorimetric assay (Folin‐Ciocalteu method) by analyzing 23 samples of virgin olive oils. A strong correlation between both methods has been found, suggesting that the colorimetric assay is reasonably valid for a rough prediction of the total phenolic content. In the literature, the level of phenolics is expressed in several different units (reference compound equivalents in case of colorimetric measurements and ppm in HPLC measurements). As these units can differ in orders of magnitude, it is necessary to convert the data to a common base before comparing or combining them.     

Pore Narrowing and Formation of Ultrathin Yttria-Stabilized Zirconia Layers in Ceramic Membranes by Chemical Vapor Deposition/Electrochemical Vapor Deposition

Chemical vapor deposition (CVD) and electrochemical vapor deposition (EVD) have been applied to deposit yttria-stabilized-zirconia (YSZ) on porous ceramic media. The experimental results indicate that the location of YSZ deposition can be varied from the surface of the substrates to the inside of the substrates by changing the CVD/EVD experimental conditions, i.e., the concentration ratio of the reactant vapors. The deposition width is strongly dependent on the deposition temperature used. The deposition of YSZ inside the pores resulted in pore narrowing and eventually pore closure, which was measured by using permpor-ometry. However, deposition of YSZ on top of porous ceramic substrates (outside the pores) did not result in a reduction of the average pore size. Ultrathin, dense YSZ layers on porous ceramic substrates can be obtained by suppressing the EVD layer growth process after pore closure.     

Abnormal grain growth in DC flash sintered 3-mol% yttria-stabilized zirconia ceramics

The origin of nonuniform microstructure and abnormal grain growth (AGG) was investigated in flash sintered 3 mol% yttria-stabilized zirconia (3YSZ) ceramics. The microstructural homogeneity decreased with increasing direct current (DC) density and with dwell time in a flash state, eventually resulting in AGG in the specimen core, the first observation of AGG in 3YSZ. Abnormal grains up to 100 μm in size emerged when the DC density was ≥160 mA/mm², and the specimen's density exceeded 99% of theoretical, starting from the cathode and propagating toward the anode. The results are discussed by comparison with established mechanisms and previous experimental evidence concerning AGG in oxides, focusing on the possible effects of the electrochemical reduction at the cathode end of the specimen.     

Multifunctional Polymer/Porous Boron Nitride Nanosheet Membranes for Superior Trapping Emulsified Oils and Organic Molecules

Effective oil/water separation and removal of organic molecules from water are of worldwide importance for water source protection. Multifunctional sorbent materials with excellent sorption capacity, stability, and recyclability properties need to be developed. Here, flexible and multifunctional polymer/porous boron nitride nanosheets (BNNSs) membranes with high water permeability, exhibiting high effectiveness and stability in the purification of simulated wastewater tainted with either oil/water emulsion or organic molecules, are reported. Remarkably, the flexible nature of these porous membranes enables simplicity of operation for water remediation processing and ease of post‐processing collection. The composite membrane also displays a remarkably high permeability of 8 × 10⁴ L μm m⁻² h⁻¹ bar⁻¹, roughly three orders of magnitude higher than pure polymer, and excellent filter efficiencies for the pharmaceuticals ciprofloxacin, chlortetracycline, and carbamazepine (up to 14.2 L g⁻¹ of BNNSs in the composite membrane for a concentration of 10 mg L⁻¹ ciprofloxacin) and the dye methylene blue (up to 9.3 L g⁻¹ of BNNSs in the composite membrane at a concentration of 30 mg L⁻¹). Exhausted membranes can be readily rejuvenated by simple washing with retention of their high‐performance characteristics. The results demonstrate the potential efficacy and practicality of these membranes for water cleaning.     

Numerical simulation of separated flows in channels

The work deals with numerical modelling of turbulent flows in channels with an expansion of the cross-section where flow separation and reattachment occur. The performance of several eddy viscosity models and an explicit algebraic Reynolds stress model (EARSM) is studied. The used test cases are flows in channels with various backward facing steps where the step is perpendicular or inclined and the top wall is parallel or deflected. Furthermore, a channel with the circular ramp is considered. The numerical solution is achieved by the finite volume method or by the finite element method. The results of both numerical approaches are compared.     

Polymer anion selective membranes for electrolytic splitting of water. Part I: stability of ion-exchange groups and impact of the polymer binder

In this study, the chemical stability of three types of the anion-exchange functional groups in an alkaline environment was tested. The following groups were selected for the test: trimethylbenzylammonium, methyl pyridinium, and tributhylbenzylphosphonium. A KOH solution with various concentrations and temperatures was used as the environment. The trimethylbenzylammonium group showed the highest stability of the materials tested under conditions relevant to water electrolysis. In the next step, four types of polymeric binders, including ethylene-co-methacrylic acid, linear polyethylene, linear polyethylene blended with poly(ethylene-co-vinylalcohol), and low-density polyethylene, were selected to determine their impact on the resulting electrochemical properties of a heterogeneous membrane. This study reveals the morphology of the membrane, ion-exchange capacity, ionic conductivity, and performance in alkaline water electrolysis conducted on a laboratory scale. The material showing the most promising properties was selected for further optimization and testing.