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Lignosulfonates(LSs), by-products from chemical pulping processes, are low-value products with limited dispersion properties. The ability of commercially available horseradish peroxidase (HRP) to polymerize LS macromolecules and improve the dispersion properties of LSs was investigated. The polymerization of LSs proceeded efficiently under mild reaction conditions in an aqueous solution with HRP/HO. Gel permeation chromatography showed a significant increase in weight-average molecular weight ( M) of sulfonated kraft lignin and sodium lignosulfonate (NaLS) by 8.5-fold and 4.7-fold, respectively. The mechanism of polymerization was investigated by elemental analysis, surface charge measurement, headspace gas chromatography, infrared spectroscopy (IR), and hydrogen nuclear magnetic resonance spectrometry (H-NMR). The functional group measurements indicated that HRP incubation did not reduce the sulfonic group content. However, it decreased the phenolic and methoxyl group contents. As the phenolic group content decreased, M increased as a power function. The polymerization was proposed to involve the random coupling of phenoxy radical intermediates. The radicals coupled with each other to form different inter-unit linkages, most of which were the β-O-4' type, as the H-NMR spectra indicated. Moreover, the HRP/HO incubation induced a significant improvement in the adsorption and dispersion properties of LSs. Therefore, the HRP/HO incubation is a promising approach for industrial applications of LSs. [ABSTRACT FROM AUTHOR]

Lignosulfonates(LSs), by-products from chemical pulping processes, are low-value products with limited dispersion properties. The ability of commercially available horseradish peroxidase (HRP) to polymerize LS macromolecules and improve the dispersion properties of LSs was investigated. The polymerization of LSs proceeded efficiently under mild reaction conditions in an aqueous solution with HRP/H 2O 2. Gel permeation chromatography showed a significant increase in weight-average molecular weight ( Mw) of sulfonated kraft lignin and sodium lignosulfonate (NaLS) by 8.5-fold and 4.7-fold, respectively. The mechanism of polymerization was investigated by elemental analysis, surface charge measurement, headspace gas chromatography, infrared spectroscopy (IR), and hydrogen nuclear magnetic resonance spectrometry ( 1H-NMR). The functional group measurements indicated that HRP incubation did not reduce the sulfonic group content. However, it decreased the phenolic and methoxyl group contents. As the phenolic group content decreased, Mw increased as a power function. The polymerization was proposed to involve the random coupling of phenoxy radical intermediates. The radicals coupled with each other to form different inter-unit linkages, most of which were the β-O-4’ type, as the 1H-NMR spectra indicated. Moreover, the HRP/H 2O 2 incubation induced a significant improvement in the adsorption and dispersion properties of LSs. Therefore, the HRP/H 2O 2 incubation is a promising approach for industrial applications of LSs. [ABSTRACT FROM AUTHOR]

The balance between free oxygen radicals and antioxidant defense systems is usually assessed by an antioxidant capacity assay. A rapid and sensitive antioxidant capacity assay is described here. It is making use of NaYF4:Yb/Er@NaYF4 core-shell upconversion nanoparticles (UCNPs) and potassium permanganate (KMnO4). In this strategy, added KMnO4 reduces the green (540 nm) emission of the UCNPs (under 980 nm photoexcitation) due to an inner filter effect. The antioxidants cysteine, ascorbic acid and glutathione (GSH) reduce the intense purple color of KMnO4 because it is reduced to Mn(II) ion. Hence, the green upconversion fluorescence is restored after the addition of antioxidants. Figures of merit for this assay (for the case of GSH) include a detection limit of 3.3 μM, a detection range that extends from 10 μM to 2.5 mM, and an assay time of a few seconds. The assay was applied to the evaluation of antioxidant capacity in human plasma samples spiked with GSH and gave satisfactory repeatability and specificity. [ABSTRACT FROM AUTHOR]

The tetragonal scheelite-type $$\hbox {Sm}^{3+}\hbox {/Bi}^{3+}$$ ions co-doped with $$\hbox {NaLa}(\hbox {MoO}_{4})_{2}$$ phosphors were synthesized by a facile sol-gel and combustion process using citric acid as complexing agent. The crystal structure and morphology of these as-prepared samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Furthermore, UV-absorption and the photoluminescence (PL) properties of these phosphors were systematically investigated and the PL of the phosphors shows strong white light emissions. Efficient energy transfer from the $$\hbox {MoO}_{4}^{2-}$$ group or $$\hbox {Bi}^{3+}$$ ions to $$\hbox {Sm}^{3+}$$ ions was established by PL investigation excited at 405 nm. The PL intensity of the studied materials was investigated as a function of different $$\hbox {Sm}^{3+}$$ and $$\hbox {Bi}^{3+}$$ concentrations. The PL investigations revealed that the phosphors exhibit apparent characteristic emissions, which is ascribed to the transition from the ground state energy level $$^{4}\hbox {G}_{5/2}$$ to excited state energy levels $$^{6}\hbox {H}_{\mathrm{J}}$$ ( $$J= 5/2, 7/2, 9/2$$ ) and the $$\hbox {NaLa}(\hbox {MoO}_{4})_{2}$$ : 4 mol% $$\hbox {Sm}^{3+}$$ and $$\hbox {NaLa}(\hbox {MoO}_{4})_{2}$$ : 4 mol% $$\hbox {Sm}^{3+}$$ , 8 mol% $$\hbox {Bi}^{3+}$$ present white emissions with the CIE coordinates of (0.350, 0.285) and (0.285, 0.229), respectively. The absolute quantum efficiencies of the phosphors are 40% ( $$\hbox {NaLa}(\hbox {MoO}_{4})_{2}$$ : 4 mol% $$\hbox {Sm}^{3+}$$ ) and 52% ( $$\hbox {NaLa}(\hbox {MoO}_{4})_{2}$$ : 4 mol% $$\hbox {Sm}^{3+}$$ , 8 mol% $$\hbox {Bi}^{3+}$$ ), respectively. [ABSTRACT FROM AUTHOR]

A facile sol-gel combustion route was reported for the direct preparation of CaZrO:Eu and CaZrO:Eu, Gd. The obtained deposits were characterized by XRD, TGA-DSC, SEM, EDS, PL measurements and microscope fluorescence. When the Gd ions were introduced in this compound, the emissions of CaZrO:Euwere remarkably enhanced. The emission spectrum of CaZrO:Eu, Gd nanocrystals exhibited a red shift compared with CaZrO:Eu samples. A new mechanism of the improved photoluminescent properties of Eu by Gd was investigated. The optimized phosphor CaZrO:5%Eu, 2%Gd could be considered an efficient red-emitting component for white lighting devices excited in the near-ultraviolet region. [ABSTRACT FROM AUTHOR]

The article focuses on the study which examines the chemical composition of Paederia scandens. It states that the aerial parts of P. scandens were extracted with ethanol and the ethanol extract was partitioned with petroleum ether and were investigated through nuclear magnetic resonance (NMR) and mass spectrometry. Result shows that an ester carbonyl correlated with the sulfur methyl group shows the presence of the partial structure of two nonequivalent hydrogen.