Photocatalytic Carbon Dioxide Conversion by Structurally and Materially Modified Titanium Dioxide Nanostructures.

TiO2 has aroused considerable attentions as a promising photocatalytic material for decades due to its superior material properties in several fields such as energy and environment. However, the main dilemmas are its wide bandgap (3-3.2 eV), that restricts the light absorption in limited light wavelength region, and the comparatively high charge carrier recombination rate of TiO2, is a hurdle for efficient photocatalytic CO2 conversion. To tackle these problems, lots of researches have been implemented relating to structural and material modification to improve their material, optical, and electrical properties for more efficient photocatalytic CO2 conversion. Recent studies illustrate that crystal facet engineering could broaden the performance of the photocatalysts. As same as for nanostructures which have advantages such as improved light absorption, high surface area, directional charge transport, and efficient charge separation. Moreover, strategies such as doping, junction formation, and hydrogenation have resulted in a promoted photocatalytic performance. Such strategies can markedly change the electronic structure that lies behind the enhancement of the solar spectrum harnessing. In this review, we summarize the works that have been carried out for the enhancement of photocatalytic CO2 conversion by material and structural modification of TiO2 and TiO2-based photocatalytic system. Moreover, we discuss several strategies for synthesis and design of TiO2 photocatalysts for efficient CO2 conversion by nanostructure, structure design of photocatalysts, and material modification.

A randomized controlled trial of the safety and efficacy of preoperative rectal misoprostol for prevention of intraoperative and postoperative blood loss at elective cesarean delivery.

OBJECTIVE: To assess the safety and efficacy of preoperative rectal misoprostol for the prevention of intraoperative and postoperative blood loss in women undergoing elective cesarean delivery. METHODS: A single-blind randomized controlled trial of 200 full-term pregnant women scheduled for elective cesarean delivery. Computer-generated randomization allocated women to receive 400 µg rectal misoprostol at urinary catheter insertion plus 400 µg rectally after abdominal closure (preoperative group, n=100) or 800 µg of rectal misoprostol after abdominal closure (postoperative group, n=100). Primary outcome was intraoperative blood loss. RESULTS: Intraoperative blood loss was significantly lower in the preoperative misoprostol group compared with the postoperative group (528.7 ± 114.8 mL vs 788.6 ± 165.8 mL; P<0.001). Blood loss during the first 24 hours after delivery was also lower in the preoperative group (199.3 ± 84.5 mL vs 302.9 ± 125.6 mL; P<0.001). Fewer women in the preoperative group needed additional uterotonics (7 vs 21; P<0.001). After delivery, the decrease in both hemoglobin and hematocrit levels was significantly less in the preoperative group (-6.8 vs -12.8% and -6.05 vs -17.8%, respectively; P<0.001). CONCLUSION: Preoperative rectal administration of misoprostol significantly reduced intraoperative and postoperative blood loss during and after elective cesarean delivery. ClinicalTrial.gov ID: NCT03680339. Date of registration 9/2018.