The increasing acceptance of ready to eat food generates demand on development of active and intelligent food packaging material. Even though many polymers have been used for the packaging, they have ...limitations for broad applications. Among the various polymers, Poly Vinyl Alcohol is a promising film forming polymer with highly flexible, emulsifying and adhesive properties. A variety of nano-fabrication techniques have already been reported to improve the mechanical and antimicrobial properties of PVA to exploit its wider applications. In the present study, starch-PVA based composite films incorporated with zinc oxide nanoparticles and phytochemicals were prepared by solvent casting technique. The films were characterized by XRD, FT-IR, UV–Vis spectrometry and SEM. The developed nanocomposite films were demonstrated to have enhanced water barrier, mechanical and antimicrobial properties. The unique features of the nanocomposite with its pH indication property demonstrated in the study indicate its potential usage in food packaging applications.
•pH sensing antimicrobial wraps were prepared and characterized.•Films were found to be water resistant with excellent UV-light barrier properties.•Microbial barrier ability also makes it suitable for packaging foods.
The fruits of Chinese hawthorn (Crataegus pinnatifida) have been used as the functional food and folk medicine due to potent antioxidant activity. In this study, polyphenols were extracted from the ...fruits of Chinese hawthorn and further added into chitosan-gelatin blend films to develop active packaging. The microstructure, physical, mechanical, barrier and antioxidant properties of the films were investigated in details. Results showed epicatechin, chlorogenic acid and procyanidin B2 were the main polyphenols in the extract of hawthorn fruits. The inner microstructure of chitosan-gelatin blend films became more compact when the extract was incorporated. The intermolecular interactions between film matrix and the extract were through hydrogen bonding and electrostatic interactions. The incorporation of the extract remarkably increased the thickness, tensile strength and elongation at break of chitosan-gelatin blend films. However, the moisture content, water vapor permeability and light transmittance of chitosan-gelatin blend films were significantly reduced by the addition of the extract. Moreover, chitosan-gelatin blend films containing the extract exhibited potent free radical scavenging ability. Our results suggest Chinese hawthorn fruit extract can be used as a natural antioxidant to improve the mechanical, barrier and antioxidant properties of chitosan-gelatin blend films.
•Chinese hawthorn fruit extract was added into chitosan-gelatin blend films.•Film matrix interacted with extract via hydrogen bond and electrostatic interactions.•The extract addition enhanced the mechanical and barrier properties of the films.•Films containing the extract showed dose-dependent free radical scavenging ability.
•Four novel homogeneous polysaccharides with antioxidant activities were isolated from PKP-E.•The structural features of the 4 fractions were characterized using multiple analysis methods.•The ...backbone of 4 fractions contained →2, 6)-β-d-Man-(1→, and →6)-α-d-GalpA-(1→), analogous to pectin.•PKP-E-2-1 was the most stable and active fraction by hydroxyl and ABTS+ scavenging assays.
The polysaccharides (PKP-E) extracted from the pinecones of Pinus koraiensis were studied, which was fractionated using DEAE-52 cellulose and Sephadex G-100. Four novel polysaccharide fractions were obtained, which were PKP-E-1−1, -1−2, -2−1, and -2−2, respectively. The structural features were characterized using HPGPC, monosaccharide composition analysis, Congo red test, periodate oxidation, Smith degradation, FTIR and NMR spectroscopy. The results showed the 4 purified fractions were non-triple helical structured heteropolysaccharides and composed of l-rhamnose, l-arabinose, d-mannose, d-glucose, and d-galactose. The fractions were mainly linked by 1→6 or 1→ glycosidic bonds and the backbone of 4 fractions was probably composed of→2, 6)-β-d-Man-(1→ and α-d-GalpA-(1→), which resembles pectin. Moreover, the antioxidant activities of the polysaccharides were measured by scavenging radical capacity tests. The PKP-E-2−1 was the most stable and active fraction, and the respective IC50 for the hydroxyl and ABTS·+ radicals were 3.0 and 23.6 mg/mL.
Chemical oxidation processes have been widely applied to water treatment and may serve as a tool to minimize the release of micropollutants (e.g. pharmaceuticals and endocrine disruptors) from ...municipal wastewater effluents into the aquatic environment. The potential of several oxidants for the transformation of selected micropollutants such as atenolol, carbamazepine, 17α-ethinylestradiol (EE2), ibuprofen, and sulfamethoxazole was assessed and compared. The oxidants include chlorine, chlorine dioxide, ferrate
VI, and ozone as selective oxidants versus hydroxyl radicals as non-selective oxidant. Second-order rate constants (
k) for the reaction of each oxidant show that the selective oxidants react only with some electron-rich organic moieties (ERMs), such as phenols, anilines, olefins, and deprotonated-amines. In contrast, hydroxyl radicals show a nearly diffusion-controlled reactivity with almost all organic moieties (
k
≥
10
9
M
−1 s
−1). Due to a competition for oxidants between a target micropollutant and wastewater matrix (i.e. effluent organic matter, EfOM), a higher reaction rate with a target micropollutant does not necessarily translate into more efficient transformation. For example, transformation efficiencies of EE2, a phenolic micropollutant, in a selected wastewater effluent at pH 8 varied only within a factor of 7 among the selective oxidants, even though the corresponding
k for the reaction of each selective oxidant with EE2 varied over four orders of magnitude. In addition, for the selective oxidants, the competition disappears rapidly after the ERMs present in EfOM are consumed. In contrast, for hydroxyl radicals, the competition remains practically the same during the entire oxidation. Therefore, for a given oxidant dose, the selective oxidants were more efficient than hydroxyl radicals for transforming ERMs-containing micropollutants, while hydroxyl radicals are capable of transforming micropollutants even without ERMs. Besides EfOM, ammonia, nitrite, and bromide were found to affect the micropollutant transformation efficiency during chlorine or ozone treatment.
Berries, especially members of several families, such as Rosaceae (strawberry, raspberry, blackberry), and Ericaceae (blueberry, cranberry), belong to the best dietary sources of bioactive compounds ...(BAC). They have delicious taste and flavor, have economic importance, and because of the antioxidant properties of BAC, they are of great interest also for nutritionists and food technologists due to the opportunity to use BAC as functional foods ingredients. The bioactive compounds in berries contain mainly phenolic compounds (phenolic acids, flavonoids, such as anthocyanins and flavonols, and tannins) and ascorbic acid. These compounds, either individually or combined, are responsible for various health benefits of berries, such as prevention of inflammation disorders, cardiovascular diseases, or protective effects to lower the risk of various cancers. In this review bioactive compounds of commonly consumed berries are described, as well as the factors influencing their antioxidant capacity and their health benefits.
Sodium batteries have been regarded as promising candidates for large-scale energy storage application, provided cathode hosts with high energy density and long cycle life can be found. Herein, we ...report NASICON-structured Na
MnZr(PO
)
as a cathode for sodium batteries that exhibits an electrochemical performance superior to those of other manganese phosphate cathodes reported in the literature. Both the Mn
/Mn
and Mn
/Mn
redox couples are reversibly accessed in Na
MnZr(PO
)
, providing high discharge voltage plateaus at 4.0 and 3.5 V, respectively. A high discharge capacity of 105 mAh g
was obtained from Na
MnZr(PO
)
with a small variation of lattice parameters and a small volume change on extraction of two Na
ions per formula unit. Moreover, Na
MnZr(PO
)
exhibits an excellent cycling stability, retaining 91% of the initial capacity after 500 charge/discharge cycles at 0.5 C rate. On the basis of structural analysis and density functional theory calculations, we have proposed a detailed desodiation pathway from Na
MnZr(PO
)
where Mn and Zr are disordered within the structure. We further show that the cooperative Jahn-Teller distortion of Mn
is suppressed in the cathode and that Na
MnZr(PO
)
is a stable phase.
We report the hydroxide (OH
) and oxide (O
) experimental electroadsorption free energies, their dependences on pH, and their correlations to the oxygen evolution reaction (OER) electrocatalysis on ...RuO
(110) surface. The Sabatier principle predicts that catalyst is most active when the intermediate stabilization is moderate, not too strong such that the bound intermediate disrupts the subsequent catalytic cycle, nor too weak such that the surface is ineffective. For decades, researchers have used this concept to rationalize the activity trend of many OER electrocatalysts including RuO
, which is among the state-of-the-art OER catalysts. In this article, we report an experimental assessment of the Sabatier principle by comparing the oxygen electroadsorption energy to the OER electrocatalysis for the first time on RuO
. We find that the OH
and O
electroadsorption energies on RuO
(110) depend on pH and obey the scaling relation. However, we did not observe a direct correlation between the OH
and O
electroadsorption energies and the OER activity in the comparative analysis that includes both RuO
(110) and IrO
(110). Our result raises a question of whether the Sabatier principle can describe highly active electrocatalysts, where the kinetic aspects may influence the electrocatalysis more strongly than the electroadsorption energy, which captures only the thermodynamics of the intermediates and not yet kinetics.
Direct C–H functionalization of aromatic compounds is a useful synthetic strategy that has garnered much attention because of its application to pharmaceuticals, agrochemicals, and late-stage ...functionalization reactions on complex molecules. On the basis of previous methods disclosed by our lab, we sought to develop a predictive model for site selectivity and extend this aryl functionalization chemistry to a selected set of heteroaromatic systems commonly used in the pharmaceutical industry. Using electron density calculations, we were able to predict the site selectivity of direct C–H functionalization in a number of heterocycles and identify general trends observed across heterocycle classes.
This study investigated the effect of blanching pomegranate seeds (PS) on oil yield, refractive index (RI), yellowness index (YI), conjugated dienes (K232), conjugated trienes (K270), total ...carotenoid content (TCC), total phenolic compounds (TPC) and DPPH radical scavenging of the extracted oil. Furthermore, phytosterol and fatty acid compositions of the oil extracted under optimum blanching conditions were compared with those from the oil extracted from unblanched PS. Three different blanching temperature levels (80, 90, and 100 °C) were studied at a constant blanching time of 3 min. The blanching time was then increased to 5 min at the established optimum blanching temperature (90 °C). Blanching PS increased oil yield, K232, K270, stigmasterol, punicic acid, TPC and DPPH radical scavenging, whereas YI, β-sitosterol, palmitic acid and linoleic acid were decreased. The RI, TCC, brassicasterol, stearic acid, oleic acid and arachidic acid of the extracted oil were not significantly (
> 0.05) affected by blanching. Blanching PS at 90 °C for 3 to 5 min was associated with oil yield, TPC and DPPH. Blanching PS at 90 °C for 3 to 5 min will not only increase oil yield but could also improve functional properties such as antioxidant activity, which are desirable in the cosmetic, pharmaceutical, nutraceutical and food industries.
Alloy nanoparticles are important in many fields, including catalysis, plasmonics, and electronics, due to the chemical and physical properties that arise from the interactions between their ...components. Typically, alloy nanoparticles are made by solution-based synthesis; however, scanning-probe-based methods offer the ability to make and position such structures on surfaces with nanometer-scale resolution. In particular, scanning probe block copolymer lithography (SPBCL), which combines elements of block copolymer lithography with scanning probe techniques, allows one to synthesize nanoparticles with control over particle diameter in the 2–50 nm range. Thus far, single-element structures have been studied in detail, but, in principle, one could make a wide variety of multicomponent systems by controlling the composition of the polymer ink, polymer feature size, and metal precursor concentrations. Indeed, it is possible to use this approach to synthesize alloy nanoparticles comprised of combinations of Au, Ag, Pd, Ni, Co, and Pt. Here, such structures have been made with diameters deliberately tailored in the 10–20 nm range and characterized by STEM and EDS for structural and elemental composition. The catalytic activity of one class of AuPd alloy nanoparticles made via this method was evaluated with respect to the reduction of 4-nitrophenol with NaBH4. In addition to being the first catalytic studies of particles made by SPBCL, these proof-of-concept experiments demonstrate the potential for SPBCL as a new method for studying the fundamental science and potential applications of alloy nanoparticles in areas such as heterogeneous catalysis.
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