Kangwon National University

About: Kangwon National University is a education organization based out in Chuncheon, South Korea. It is known for research contribution in the topics: Population & Catalysis. The organization has 9836 authors who have published 20002 publications receiving 393562 citations. The organization is also known as: KNU.

Selective sensing of anions with calix[4]pyrroles strapped with chromogenic dipyrrolylquinoxalines.

Abstract: New calix[4]pyrroles bearing dipyrrolylquinoxaline as strapping elements have been synthesized and characterized by spectroscopic means. The binding behavior of these receptors at 25 degrees C was investigated first by proton NMR spectroscopy in CD(3)CN/DMSO-d(6) (9:1 v/v), as well as by UV-vis spectroscopy and isothermal titration calorimetry (ITC) in CH(3)CN/DMSO (97:3 v/v). The receptors displayed a selective colorimetric response when exposed to the fluoride, dihydrogen phosphate, and acetate anions (studied in the form of the corresponding tetrabutylammonium salts) and an enhanced affinity as compared to a comparable calix[4]pyrrole system lacking the dipyrrolylquinoxaline-containing strap.

Flexible and Self-Healing Aqueous Supercapacitors for Low Temperature Applications: Polyampholyte Gel Electrolytes with Biochar Electrodes.

Abstract: A flexible and self-healing supercapacitor with high energy density in low temperature operation was fabricated using a combination of biochar-based composite electrodes and a polyampholyte hydrogel electrolyte. Polyampholytes, a novel class of tough hydrogel, provide self-healing ability and mechanical flexibility, as well as low temperature operation for the aqueous electrolyte. Biochar is a carbon material produced from the low-temperature pyrolysis of biological wastes; the incorporation of reduced graphene oxide conferred mechanical integrity and electrical conductivity and hence the electrodes are called biochar-reduced-graphene-oxide (BC-RGO) electrodes. The fabricated supercapacitor showed high energy density of 30 Wh/kg with ~90% capacitance retention after 5000 charge–discharge cycles at room temperature at a power density of 50 W/kg. At −30 °C, the supercapacitor exhibited an energy density of 10.5 Wh/kg at a power density of 500 W/kg. The mechanism of the low-temperature performance excellence is likely to be associated with the concept of non-freezable water near the hydrophilic polymer chains, which can motivate future researches on the phase behaviour of water near polyampholyte chains. We conclude that the combination of the BC-RGO electrode and the polyampholyte hydrogel electrolyte is promising for supercapacitors for flexible electronics and for low temperature environments.

Isolation and identification of sea buckthorn (Hippophae rhamnoides) phenolics with antioxidant activity and α-glucosidase inhibitory effect.

Abstract: This study was performed to evaluate the antioxidant and α-glucosidase inhibitory effects from the extract, fractions, and isolated compounds of sea buckthorn leaves. Six compounds, kaempferol-3-O-β-d-(6′′-O-coumaryl) glycoside, 1-feruloyl-β-d-glucopyranoside, isorhamnetin-3-O-glucoside, quercetin 3-O-β-d-glucopyranoside, quercetin 3-O-β-d-glucopyranosyl-7-O-α-l-rhamnopyranoside, and isorhamnetin-3-O-rutinoside, were isolated from sea buckthorn leaf extracts. The butanol fraction (EC50 = 1.81 μg/mL) along with quercetin 3-O-β-d-glucopyranoside (EC50 = 1.86 μg/mL) had a higher DPPH radical-scavenging activity and showed stronger reducing power (OD700 = 1.83 and 1.78, respectively). The butanol fraction (477 mg GAE/g) contained the highest amount of phenolic compounds and also the most powerful α-glucosidase inhibitory effect (86%) at 5 μg/mL. The results indicate that sea buckthorn leaf extracts could potentially be used for food additives and the development of useful natural compounds.