ZnO nanopowder was prepared by a novel “solution-combustion method (SCM)” and it was used as a semiconductor photocatalyst to evaluate its photoreduction properties. Aqueous Pb-EDTA and Cu-EDTA solutions of heavy metal ions (Pb and Cu) were used for the photocatalysis reaction under UV illumination. The result was then compared with other semiconductor photocatalyst powder such as TiO2 powder (P25; Degussa) and TiO2 powder prepared by homogeneous precipitation process at low temperature (HPPLT). In the removal of Pb++ ions, the ZnO nanopowder showed 2.6 fold higher removal rate than P25 TiO2 powder and 1.8 fold higher than HPPLT TiO2. Also the ZnO nanopowder showed the highest removal rate of the Cu++ ions from the solution among the different photocatalyst powders compared. The superior photoreduction ability of the ZnO nanopowder appears to be due to its excellent UV absorption characteristics. This was confirmed by the photoluminescence (PL) measurement.
Background and ObjectivesIn order to verify that apoptosis is one of the possible mechanisms of human neonatal vascular remodeling during transition from fetal to neonatal circulation, we identified apoptosis and analyzed its mechanism by evaluating apoptosis-related genes in the umbilical vessel versus the ascending aorta, ductus arteriosus DA versus adjacent pulmonary artery and aorta, and the aorta versus its branching arteries. Materials and Methods Twenty-two umbilical cords, six ductus arteriosus with adjacent aortae and pulmonary arteries, and four aortic arches with their branching great arteries, were obtained from neonates. The presence of apoptotic cells was demonstrated by electron microscopy EM and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling TUNEL . Immunohistochemical staining and Western blotting were used for the analysis of the proteins of the apoptosis-related gene. Results Apoptosis of the smooth muscle cells of the umbilical vessels were was identified in all UCs that were examined by electron microscopy and TUNEL. The expressions of Bax and Bcl-X were shown by immunohistochemistry to be stronger in the umbilical artery than in the neonatal aorta, although Bcl-2 was weak in both arteries. In the immunoblot analysis of the UCs, the expression of the proapoptotic short isoform of Bcl-X was stronger than in other tissue, and caspase-3 was selectively activated whereas it was not in the other components of the cardiovascular system. However, the expression patterns of the Fas Ag and Fas ligand i.e. positive Fas Ag and negative Fas ligand , were similar in the umbilical artery and aorta. This Bax-associated apoptosis was also observed in other vascular sites that undergo dramatic hemodynamic changes during birth, such as, the ductus arteriosus and the branching points of the great arteries from the aortic arch. Conclusions Apoptosis is involved in the closure and regression of human umbilical vessels and the ductus arteriosus and in the remodeling of the branching great arteries during the neonatal period, where the Bax/Bcl-2/Bcl-X system, not the Fas Ag/Fas ligand system, is likely to play a key role. Korean Circulation J 2001 ; 31 7 : 681-700 KEY WORDS Apoptosis·Umbilical vessels·Ductus arteriosus·Bax·Bcl-2·Bcl-X·Caspase-3. Korean Circulation J 2001 ; 31 7 : 681-700
Photocatlytic ZnO nanopowders were synthesized by a novel method referred to as “solution-combustion method (SCM)”. They were synthesized using various oxidants and fuels. Single-phase ZnO powders were obtained. The ZnO powder synthesized using Zn(OH)2 and glycine as an oxidant and a fuel at fuel/oxidant ratio of 0.8, showed best powder characteristics such as average grain size of 30 nm and the specific surface area of 120 m2/g. The photocatalytic gold recovery efficiency by this SCM ZnO nanopowders was about 6 fold higher compared to the case by the state of the art commercial TiO2 nanopowders. The purity of recovered gold was about 99.6% in weight% and 98.8% in atomic%. Especially, in this study it was tried to recover gold metal ions from not simulated wastewater but real plating one. This technology is therefore very viable and cost-effective to obtain high purity gold from plating wastewater.
ZnO nanopowders with an average grain size of 30nm were prepared by a solution combustion method with various sintering temperatures (100-1000o C). The optical properties of the ZnO nanopowders were investigated in the temperature range of 14-150K in air. Based on the results of XRD, Photoluminescence, and excitation spectra, the ZnO powders showed wurtzite single phase with UV-blue light emitting. Deep level defects such as oxygen vacancies and Zn interstitials were not observed from the ZnO powders sintered up to 700 o C. However, these defects were observed as the sintering temperature was increased up to 900 o C. This seems to be due to the generation of oxygen vacancies and zinc interstitials. Furthermore, the blue light intensity was doubled when the synthesized ZnO powders were sintered at 700 o C. This might be very useful for high efficiency photocatalysts and the blue light emitting phosphors of displays such as field emission displays and plasma display panels.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.