RESUMEN
ABSTRACT: Carbon fibers (CFs) decorated by Co2P nanoparticles and carbon nanotubes were prepared via needle-less electrospinning technique. Formation of catalytically active Co2P nanoparticles and growth of carbon nanotubes were monitored in open and closed sintering environment at different sintering exposure times. Higher porosity, important in the catalytic reaction for easier penetration of electrolyte into the CFs, was achieved by mixing two immiscible polymers with natrium dodecyl sulfate and subsequent heat treatment process. Structure and morphology of the prepared modified carbon fibers were characterized by XRD, SEM and TEM. The time of heat exposure at the sintering temperature of 1200 °C and closure of the sintering space showed distinct effect on the growth and shape of carbon nanotubes. SEM and Raman spectroscopy revealed that closure of the system led to the formation of carbon nanotubes with smaller diameters and less structural disorder. Comparing of as-prepared CFs revealed that CFs with Co2P sintered in the closed system exhibited the best electrocatalytic activity for hydrogen evolution reaction due to lower overpotential and smaller Tafel slope in acidic solution.
RESUMEN
The lipid and lipoprotein metabolism was examined in fortyfour long distance runners and in a cohort of sixty-five untrained subjects as well as in thirty-two runners before and immediately after 38- and 40-kilometer runs respectively. There was observed a significant increase of high density lipoprotein cholesterol in the runners, whereas very low density lipoprotein cholesterol showed a marked decrease. The low density lipoprotein cholesterol/high density lipoprotein cholesterol quotient (arteriosclerotic quotient) was found to be markedly reduced in the runners. There was no statistical difference in total cholesterol and low density lipoprotein cholesterol between long distance runners following sports as a pastime and untrained subjects. Post-heparin lipase and the rate of lipolysis were markedly increased in subjects following sports as a recreation. Parallelisms were observable between lipid values and lipoprotein percentages determined by disk electrophoresis. The proportions of alpha-lipoprotein, beta-lipoprotein, and pre-beta-lipoprotein in runners were found to be increased, unchanged, and reduced respectively. The increase in alpha-lipoprotein was accompanied by a shift in the spectrum of alpha-lipoprotein subfractions. After the 38- and 40-kilometer run, respectively, there were determined an increase in TGL and very low density lipoprotein cholesterol and a decrease in both post-heparin lipase and rate of lipolysis. The other cholesterol parameters showed no significant variations after straining. Whereas Apo A, like high density lipoprotein cholesterol, did not change during running, Apo B showed a marked increase. The results were discussed with due consideration of those reported by other authors.
Asunto(s)
Lipoproteínas/metabolismo , Carrera , Medicina Deportiva , Factores de Edad , Colesterol/metabolismo , HDL-Colesterol , LDL-Colesterol , Humanos , Lipoproteína Lipasa/sangre , Lipoproteína Lipasa/metabolismo , Lipoproteínas/sangre , Lipoproteínas HDL/metabolismo , Lipoproteínas LDL/metabolismo , Masculino , Persona de Mediana EdadRESUMEN
The lipid metabolism and the lipoprotein metabolism was examined in 44 long-distance runners (people's athletics) and a group of 65 untrained persons as well as in 32 runners before and immediately after a 38-km and a 40-km-run, respectively. High density lipoprotein cholesterol (HDLC) was significantly increased in the runners, whereas very low density lipoprotein cholesterol (VLDLC) was found decreased. The quotient LDLC/HDLC (quotient of arteriosclerosis) is clearly decreased in runners. Total cholesterol and low density lipoprotein cholesterol (LDLC) of runners (people's athletics) and untrained persons were statistically not different. The post-heparin-lipase (pHL) and the rate of lipolysis pHL appeared clearly increased in persons participating in people's athletics. There were parallelities between the lipid values and the disc-electrophoretically established percental proportions of lipoproteins. The proportion of alpha-lipoprotein (Lp) of the runners was increased, the beta-Lp unchanged and the pre-beta-Lp decreased. The increase of the alpha-Lp was concomitant with a shift of the spectre of the alpha-Lp-subfractions. After the running (38 and 40 km) the triglycerides and VLDLC were increased, the pHL-activity and the rate of lipolysis pHL were decreased. In the other cholesterol parameters no significant shifts appeared after load. While Apo A does not change under the influence of the running, like HDLC, Apo B clearly increased. The results were discussed, taking into consideration the results of other authors.