UREA AND SERUM PROTEINS IN CIRCUMSCRIBED PROFOUND BURN ON COMBINED TREATMENT

No abstrac

FREE RADICAL OXIDATION AND ERYTHROCYTE AGGREGATION AFTER THERMIC INJURY EFFECT OF ALPHATOCOPHEROL

No abstrac

EFFECT OF LIPID PEROXIDE OXIDATION ON ERYTHROCYTE FLEXIBILITY IN BURNS AND ALPHA-TOCOFEROL TREATMENT

No abstrac

ALPHA-TOCOPHEROL STABILIZES ERYTHROCYTE MEMBRANE DURING THE EARLY STAGE AFTER THERMAL TRAUMA

Standard thermal trauma of 3rda - 3rdb degree, of 15-20 per cent of body surface was induced on white male Wistar rats narcotized with thiopental The changes of the concentration of thioharhituric acid (TBA)- reactive products, the activity of some antioxidant enzymes such as superoxide dismutase (SOD), glucose-6-phosphate dehydrogenase (G-6-PD), and catalase as well as the percentage of haemolysis were investigated during the early post-burn period (24, 48, and 72 hours after burning). It was demonstrated that erythrocyte haemolysis increased along with activation of lipid peroxidation (LPO) after thermic injury. Alpha-tocopherol treatment in a dose of 20 mg/kg body mass reduced the elevated levels of TBA-reactive products and enhanced erythrocytic antioxidant defence and resistance. It could be clarified that LPO activation played an important role in the haemolysis and that alpha-tocopherol stabilized erythrocyte membrane after burns

EVIDENCE FOR FREE-RADICAL MEDIATED LIPID PEROXIDATION IN RATS AFTER COLD-IMMERSION STRESS

The role of cold immersion stress for the free-radical mediated lipid peroxidation in rat plasma and erythrocytes was studied. A model of cold-induced stress in rats was created. A significant increase of the level of thiobarbituric acid-reactive substances (TBARS) in plasma was found after chilling. Activated catabolic processes and xanthine-oxidase reactions during hypoxia could cause the increase measured in plasma levels of uric acid one hour after cold stress. A decrease in the antioxidant defence measured by uric acid consumption in rat blood plasma took also place already at the 3rd hour after chilling. These effects were not accompanied neither by elevated levels of TBARS, nor by a decrease in the reduced glutathione or elevated ratio of oxidized/ total glutathione in erythrocytes. The results indicated that lipid peroxidation was a component of the cold-induced stress in rats

Preparation and Properties of Nanocomposites from Pristine and Modified SWCNTs of Comparable Average Aspect Ratios

Low color, flexible, space-durable polyimide films with inherent and robust electrical conductivity to dissipate electrostatic charge (ESC) have been under investigation as part of a materials development activity for future NASA space missions. The use of single-walled carbon nanotubes (SWCNTs) is one means to achieving this goal. Even though the concentration of SWCNTs needed to achieve ESC dissipation is typically low, it is dependent upon purity, size, dispersion, and functionalization. In this study, SWCNTs prepared by the electric arc discharge method were used to synthesize nanocomposites using the LaRC(TradeMark) CP2 backbone as the matrix. Pristine and functionalized SWCNTs were mixed with an alkoxysilane terminated amide acid of LaRC(TradeMark) CP2 and the soluble imide form of the polymer and the resultant nanocomposites evaluated for mechanical, thermal, and electrical properties. Due to the preparative conditions for the pristine and functionalized SWCNTs, the average aspect ratio for both was comparable. This permitted the assessment of SWCNT functionalization with respect to various interactions (e.g. van der Waals, hydrogen bonding, covalent bond formation, etc.) with the matrix and the macroscopic effects upon nanocomposite properties. The results of this study are described herein

Preparation and Properties of Nanocomposites Prepared From Shortened, Functionalized Single-Walled Carbon Nanotubes

As part of a continuing materials development activity, low color space environmentally stable polymeric materials that possess sufficient electrical conductivity for electrostatic charge dissipation (ESD) have been investigated. One method of incorporating sufficient electrical conductivity for ESD without detrimental effects on other polymer properties of interest (i.e., optical and thermo-optical) is through the incorporation of single-walled carbon nanotubes (SWNTs). However, SWNTs are difficult to fully disperse in the polymer matrix. One means of improving dispersion is by shortening and functionalizing SWNTs. While this improves dispersion, other properties (i.e., electrical) of the SWNTs can be affected which can in turn alter the final nanocomposite properties. Additionally, functionalization of the polymer matrix can also influence nanocomposite properties obtained from shortened, functionalized SWNTs. The preparation and characterization of nanocomposites fabricated from a polyimide, both functionalized and unfunctionalized, and shortened, functionalized SWNTs will be presented

Designing all-graphene nanojunctions by covalent functionalization

We investigated theoretically the effect of covalent edge functionalization, with organic functional groups, on the electronic properties of graphene nanostructures and nano-junctions. Our analysis shows that functionalization can be designed to tune electron affinities and ionization potentials of graphene flakes, and to control the energy alignment of frontier orbitals in nanometer-wide graphene junctions. The stability of the proposed mechanism is discussed with respect to the functional groups, their number as well as the width of graphene nanostructures. The results of our work indicate that different level alignments can be obtained and engineered in order to realize stable all-graphene nanodevices

Mechanically Assisted Exfoliation and Functionalization of Thermally Converted Graphene Sheets

Published versio

Structurally driven one-dimensional electron confinement in sub-5-nm graphene nanowrinkles

Graphene-based carbon materials such as fullerenes, carbon nanotubes, and graphenes have distinct and unique electronic properties that depend on their dimensionality and geometric structures. Graphene wrinkles with pseudo one-dimensional structures have been observed in a graphene sheet. However, their one-dimensional electronic properties have never been observed because of their large widths. Here we report the unique electronic structure of graphene nanowrinkles in a graphene sheet grown on Ni(111), the width of which was small enough to cause one-dimensional electron confinement. Use of spatially resolved, scanning tunnelling spectroscopy revealed bandgap opening and a one-dimensional van Hove singularity in the graphene nanowrinkles, as well as the chemical potential distribution across the graphene nanowrinkles. This observation allows us to realize a metallic-semiconducting-metallic junction in a single graphene sheet. Our demonstration of one-dimensional electron confinement in graphene provides the novel possibility of controlling its electronic properties not by chemical modification but by 'mechanical structuring'.open