Search results for "Oxide"

Freezing without surrounding cryomedium preserves the endothelium and its function in human internal mammary arteries

2005

Abstract Purpose Cryopreserved human blood vessels may become important tools in bypass surgery. Optimal cryopreservation of an arterial graft should, therefore, preserve both histological and physiological characteristics of smooth muscle and endothelium comparable to the unfrozen artery. Methods Rings from human internal mammary arteries (IMA) were investigated in vitro either unfrozen or after immersion into a cryomedium (RPMI 1640 containing 1.8 M Me2SO and 0.1 M sucrose) and cryostorage with and without surrounding medium. Results In unfrozen IMA, neither contractile responses to noradrenaline (NA) nor endothelium-dependent relaxant responses to acetylcholine (ACH) was modified after e…

Ascorbic Acid Oxidation in Sucrose Aqueous Model Systems at Subzero Temperatures

2004

The reduction of Tempol by ascorbic acid in concentrated sucrose solutions was measured by electron paramagnetic resonance (EPR) at temperatures ranging from 16 to −16 °C. This method allowed the determination of the rate constants (k) of this fast reaction, by recording the Tempol reduction as a function of time. The two reactants were initially separated and had to migrate for the reaction to occur. The experimental findings were compared with predicted values according to the equation for diffusion-controlled reaction proposed by Atkins. The experimental reaction rate constants were observed to be lower than the calculated ones. However, the experimental values were found to be controlle…

Inhibitoren der Korrosion (9) Nachweis der Sekundärinhibitoren bei einigen Sulfoxiden, Triphenylarsinoxid und einigen Sulfoniumsalzen

1971

Die Schutzwerte von Dibenzylsulf-oxyd und strukturell verwandten Ver-bindungen sowie von Triphenylarsin-oxyd werden bestimmt. Sulfoxyde und Arsinoxyde werden (a) nach Protonierung in die kathodischen Bereiche gefuhrt und (b) nach Elektronenaufnahme in die ko-ordinationsfahigen Sekundarinhibitoren (Thioather und tert. Arsine) umgewan-delt. Die Sekundarinhibitoren ziehen entweder auf das Metall auf und unter-drucken dann die Auflosung des Eisens oder werden nicht am Metall fixiert (z. B. Diphenylsulfid) und entfalten dann keinen Schutz. Im Falle des Dibenzyl-sulfoxyds konnen ca. 90% des einge-setzten Dibenzylsulfoxyds als Dibenzyl-sulfid vom Eisen abgelost werden; 16% an unverandertem Dibenzy…

Dependency of the in vitro stabilization of differentiated functions in liver parenchymal cells on the type of cell line used for co-culture.

1992

The differentiation status in cultures of primary rat liver parenchymal cells was determined by measuring the activities of various xenobiotic metabolizing enzymes. Most enzyme activities dropped rather rapidly in monocultures of parenchymal cells. The protein content and the activities of cytosolic epoxide hydrolase, glutathione S-transferase, and alpha-naphthol UDP-glucuronosyl transferase were, however, well stabilized in 7-day-old co-cultures of parenchymal cells with two different lines of rat liver nonparenchymal epithelial cells (NEC1 and NEC2). Phenol sulfotransferase and microsomal epoxide hydrolase activity were reduced in this coculture system after 7 days to about 30 and 20% of …

A High-Performance Asymmetric Supercapacitor Based on Tungsten Oxide Nanoplates and Highly Reduced Graphene Oxide Electrodes.

2021

Tungsten oxide/graphene hybrid materials are attractive semiconductors for energy-related applications. Herein, we report an asymmetric supercapacitor (ASC, HRG//m-WO3 ASC), fabricated from monoclinic tungsten oxide (m-WO3 ) nanoplates as a negative electrode and highly reduced graphene oxide (HRG) as a positive electrode material. The supercapacitor performance of the prepared electrodes was evaluated in an aqueous electrolyte (1 m H2 SO4 ) using three- and two-electrode systems. The HRG//m-WO3 ASC exhibits a maximum specific capacitance of 389 F g-1 at a current density of 0.5 A g-1 , with an associated high energy density of 93 Wh kg-1 at a power density of 500 W kg-1 in a wide 1.6 V ope…

Cover Feature: Boosting the Supercapacitive Behavior of CoAl Layered Double Hydroxides via Tuning the Metal Composition and Interlayer Space (Batteri…

2020

Structure of nanoporous carbon materials for supercapacitors

2012

Activated carbons with highly developed porous structure and nanosized pores (8 - 11 A) were prepared from alder wood using thermochemical activation method with sodium hydroxide. Properties of the obtained activated carbons were examined by benzene and nitrogen sorption, X-Ray diffraction and Raman spectroscopy. Tests of activated carbons as electrodes in supercapacitors were performed as well. It was found that specific surface area of above mentioned activated carbons was 1800 m 2 /g (Dubinin - Radushkevich). Raman spectroscopy demonstrated the presence of ordered and disordered structures of graphite origin. The performance of activated carbons as electrodes in supercapacitors have show…

Layered double hydroxide nanocomposites based on carbon nanoforms

2020

Abstract Carbon nanoform (CNF)/layered double hydroxide (LDH) nanocomposites have been widely studied in recent years thanks to the combination of properties of both LDH and carbon nanomaterials. They exhibit improved or unexpected properties as a consequence of their hierarchical structures. There are three main reported approaches to prepare the nanocomposites: reassembly of nanocarbons and LDHs, direct formation of LDHs on nanocarbon materials, and the direct synthesis of nanocarbons on the LDH phase. The resulting CNF/LDH nanocomposites exhibit improved conductivity, mechanical properties, and redox reactivity; moreover, the hybridization confers hierarchical porosities and better dispe…

Probing the superconducting state of UPd2Al3 thin films by tunneling spectroscopy

1997

Abstract Giaever-type planar cross junctions of thin films of the heavy fermion superconductor UPd2Al3 and counter-electrodes of Au, Ag and Al were prepared. Tunneling barriers consisting of the native oxide layer of UPd2Al3 and artificial barriers of AlOx and UOx were investigated. The junctions without artificial barrier show a lack of reproducebility. On some junctions a BCS-like tunneling conductivity with a ratio of 2Δ 0 /k B T c ⋍ 3.8 was observed. Using oxidized Al deposited at room temperature as a barrier no substantial increase of the junction resistance occured. With Uraniumoxide a much higher resistance was obtained, but an association of the bias dependent junction conductivity…

Trapping of quasiparticles of a nonequilibrium superconductor

2000

We have performed experiments where hot electrons are extracted from a normal metal into a superconductor through a tunnel junction. We have measured the cooling performance of such NIS junctions, especially in the cases where another normal metal electrode, a quasiparticle trap, is attached to the superconductor at different distances from the junction in direct metal-to-metal contact or through an oxide barrier. The direct contact at a submicron distance allows superior thermalization of the superconductor. We have analyzed theoretically the heat transport in this system. From both experiment and theory, it appears that NIS junctions can be used as refrigerators at low temperatures only w…