다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Films and powders of TiO 2- x N x have revealed an improvement over titanium dioxide (TiO 2 ) under visible light (wavelength 2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calculations and x-ray photoemission spectroscopy.

/pdf/visible-light-photocatalysis-in-nitrogen-doped-titanium-np6nklr9gh.pdf

Visible-Light Photocatalysis in Nitrogen-Doped Titanium Oxides

Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

The surface science of titanium dioxide

Air-water interfacial fluidic sonolysis in superhydrophobic silicon-nanowire-embedded system for fast water treatment

The aim of this study was to estimate the total greenhouse gas (GHG) emissions generated from whole life cycle stages of a sewer pipeline system and suggest the strategies to mitigate GHG emissions from the system. The process-based life cycle assessment (LCA) with a city-scale inventory database of a sewer pipeline system was conducted. The GHG emissions (direct, indirect, and embodied) generated from a sewer pipeline system in Daejeon Metropolitan City (DMC), South Korea, were estimated for a case study. The potential improvement actions which can mitigate GHG emissions were evaluated through a scenario analysis based on a sensitivity analysis. The amount of GHG emissions varied with the size (150, 300, 450, 700, and 900 mm) and materials (polyvinyl chloride (PVC), polyethylene (PE), concrete, and cast iron) of the pipeline. Pipes with smaller diameter emitted less GHG, and the concrete pipe generated lower amount of GHG than pipes made from other materials. The case study demonstrated that the operation (OP) stage (3.67 × 104 t CO2eq year−1, 64.9%) is the most significant for total GHG emissions (5.65 × 104 t CO2eq year−1) because a huge amount of CH4 (3.51 × 104 t CO2eq year−1) can be generated at the stage due to biofilm reaction in the inner surface of pipeline. Mitigation of CH4 emissions by reducing hydraulic retention time (HRT), optimizing surface area-to-volume (A/V) ratio of pipes, and lowering biofilm reaction during the OP stage could be effective ways to reduce total GHG emissions from the sewer pipeline system. For the rehabilitation of sewer pipeline system in DMC, the use of small diameter pipe, combination of pipe materials, and periodic maintenance activities are suggested as suitable strategies that could mitigate GHG emissions. This study demonstrated the usability and appropriateness of the process-based LCA providing effective GHG mitigation strategies at a city-scale sewer pipeline system. The results obtained from this study could be applied to the development of comprehensive models which can precisely estimate all GHG emissions generated from sewer pipeline and other urban environmental systems.

Estimation of greenhouse gas emissions from sewer pipeline system

Polychlorinated dibenzo-p-dioxins (PCDDs) are extremely toxic and persistent environmental pollutants. Their chemical reactivities and other physicochemical/biological properties show a strong dependence on the chlorination pattern. With increasing the number of chlorines, dioxin congeners become more electronegative and gain higher electron affinities. The vertical electron affinities (VEA) are related with the LUMO energies of neutral molecules. LUMO energies of all PCDD congeners were calculated at the B3LYP/6-31G** level and those of some selected congeners at the level of B3LYP/6-311G**//B3LYP/6-31G** and B3LYP/cc-pvtz/ /B3LYP/6-31G**. The total energies of neutral and anionic species for dibenzo-p-dioxins (DD), 1469-TCDD, 2378-TCDD, and OCDD were calculated at the level of B3LYP/6,31G**, B3LYP/aug-cc-pvdz, and B3LYP/ aug-cc-pvtz//B3LYP/6-31G**. By using the four congeners with D 2 h symmetry as reference molecules, we could estimate VEA (B3LYP/aug-cc-pvdz) of 75 PCDD congeners based on the linear correlations between LUMO energy and VEA (B3LYP/6-31G**) and between VEA (B3LYP/6-31G**) and VEA (B3LYP/aug-cc-pvtz//B3LYP/6-31G**). Results show that all PCDDs with the number of Cl ≥ 3 have positive electron affinities. The PCDD electron affinity values provided in this work can be a useful data set in understanding the congener-specific reactivities of dioxins in various environmental media.

/pdf/dft-calculation-on-the-electron-affinity-of-polychlorinated-26fttaygvh.pdf

DFT Calculation on the Electron Affinity of Polychlorinated Dibenzo-p-dioxins

Synthesis and reactions of 1‐(2‐oxopropyl)pyridazin‐6‐ones

Wide attentions are recently focused on the use of surfactants for the remediation of contaminated soil and groundwater UV photolysis has been often studied for the post-treatment of the contaminated surfactant solutions In this study, we report a novel photolysis system where a recalcitrant perchlorocompound can be degraded in a surfactant solution under visible light ( λ>420 nm ) illumination: CCl4 could be successfully dechlorinated in a nonionic surfactant (Brij) solution under visible light The addition of Fe3+ in this surfactant solution enables the visible light induced dechlorination of CCl4 because Fe3+ ions form complexes with the surfactant molecules (carrying the polyoxyethylene group) to act as a visible light sensitizer A broad UV-Vis absorption band, which is centered around 370 nm and extended into the visible region, appears as a result of this complexation The generation of this visible light absorption band is observed only in the Brij+Fe3+ solution and absent in other surfactant+Fe3+ solutions Accordingly, the visible light induced dechlorination of CCl4 is significant only in the Brij+Fe3+ solution It is proposed that the Fe(III)–Brij complexing centers are excited by absorbing visible light and subsequently transfer electrons to adjacent CCl4 molecules confined within the same micelle Direct evidences for the visible light activation of the Fe3+-complexed Brij micelles were obtained from the photocurrent measurement Effects of various experimental parameters and proposed mechanism for this visible light photochemical process are discussed

Novel complexation between ferric ions and nonionic surfactants (Brij) and its visible light activity for CCl4 degradation in aqueous micellar solutions

Wonyong Choi

Papers

Air-water interfacial fluidic sonolysis in superhydrophobic silicon-nanowire-embedded system for fast water treatment

Estimation of greenhouse gas emissions from sewer pipeline system

DFT Calculation on the Electron Affinity of Polychlorinated Dibenzo-p-dioxins

Synthesis and reactions of 1‐(2‐oxopropyl)pyridazin‐6‐ones

Novel complexation between ferric ions and nonionic surfactants (Brij) and its visible light activity for CCl4 degradation in aqueous micellar solutions