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

Ke Sun,† Shaohua Shen,*,‡,§ Yongqi Liang, Paul E. Burrows, Samuel S. Mao,* and Deli Wang*,†,⊥,# †Department of Electrical and Computer Engineering, Material Science Program, and QualComm Institute, University of California at San Diego, La Jolla, California 92093, United States ‡International Research Center for Renewable Energy, State Key Lab of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China Department of Mechanical Engineering, University of California at Berkeley, Berkeley, California 94720, United States Department of Chemistry, Chemical Biological Center, Umea ̊ University, Linnaeus vag̈, 6 901 87 Umea,̊ Sweden Samuel Mao Institute of New Energy, Science Hall, 1003 Shangbu Road, Shenzhen, 518031, China

Enabling silicon for solar-fuel production

Cd1−xZnxS solid solution with nano-twin structures are synthesized and exhibit superior photocatalytic activities for H2 evolution from water under visible light irradiation (λ ≥ 430 nm) without noble metal co-catalysts. Such Cd0.5Zn0.5S nanocrystals show the highest activity for hydrogen evolution with an extremely high apparent quantum yield (AQY = 43%) at 425 nm, achieving a hydrogen evolution rate of 1.79 mmol h−1 without noble metals. The hydrogen evolution rate of 1.70 mmol h−1 was achieved under simulated sunlight conditions (without infrared light). The “back to back” potential formed by parallel nano-twins in the Cd1−xZnxS crystals can significantly improve the separation of the photo-generated electrons/holes (preventing their recombination) thus enhancing the photocatalytic activity. Photodeposition experiments of noble metals strongly support such a mechanism. It is found that noble metals were selectively photo-deposited at central regions between the twin boundaries. The concentration of free electrons at the central region of twins was markedly higher and the twins can effectively separate the H2 evolution sites (electrons) from oxidation reaction sites (holes).

Twins in Cd1−xZnxS solid solution: Highly efficient photocatalyst for hydrogen generation from water

Semiconductor nanostructure-based photoelectrochemical water splitting: A brief review

Highly selective hydrogenation of cinnamaldehyde to cinnamyl alcohol with 2-propanol was achieved using SiC-supported Au nanoparticles as photocatalyst. The hydrogenation reached a turnover frequency as high as 487 h–1 with 100% selectivity for the production of alcohol under visible light irradiation at 20 °C. This high performance is attributed to a synergistic effect of localized surface plasmon resonance of Au NPs and charge transfer across the SiC/Au interface. The charged metal surface facilitates the oxidation of 2-propanol to form acetone, while the electron and steric effects at the interface favor the preferred end-adsorption of α,β-unsaturated aldehydes for their selective conversion to unsaturated alcohols. We show that this Au/SiC photocatalyst is capable of hydrogenating a large variety of α,β-unsaturated aldehydes to their corresponding unsaturated alcohols with high conversion and selectivity.

Visible-Light-Driven Selective Photocatalytic Hydrogenation of Cinnamaldehyde over Au/SiC Catalysts.

A SiC way to split water: Illuminated p-type 4H-SiC, as a photocathode short-circuited to Pt, was found to split water (see picture). The hydrogen generated is stored to a considerable extent in the solid.

SiC: A Photocathode for Water Splitting and Hydrogen Storage

Chemical transformations in paintings often induce discolorations, disturbing the appearance of the image. For an appropriate conservation of such valuable and irreplaceable heritage objects, it is important to have a good know-how on the degradation processes of the (historical) materials: which pigments have been discolored, what are the responsible processes, and which (environmental) conditions have the highest impact on the pigment degradation and should be mitigated. Pigment degradation is already widely studied, either by analyzing historical samples or by accelerated weathering experiments on dummies. However, in historic samples several processes may have taken place, increasing the complexity of the current state, while aging experiments are time-consuming due to the often extended aging period. An alternative method is proposed for a fast monitoring of degradation processes of semiconductor pigments, using an electrochemical setup mimicking the real environment and allowing the identification o...

Electrochemical photodegradation study of semiconductor pigments : influence of environmental parameters

An approach for wet-chemical atomic layer etching (WALE) of semiconductors is described. The surface chemistry of InAs was investigated for HCl/H2O2 solutions suitable for controlled etching in the low etch rate range (<0.1–10 nm min −1 ). Kinetic studies were performed using inductively coupled plasma – mass spectrometry (ICP-MS). As for GaAs and InGaAs, the importance of the Cl − ion for the etching kinetics is demonstrated and a chemical reaction scheme is presented to help understand the surface chemistry. A detailed study of an alternative two-step etching process was performed. A quantitative ICP-MS analysis of the oxide formed in O3/H2O solution and the dissolution in HCl was performed suggesting that the removal of oxidized In products is the slow step in the dissolution reaction. The reoxidation of oxide-free InAs (100) surfaces in air is discussed. The etch rate range and the surface morphology control after etching show that the investigated wet-chemical approach for atomic-layer etching is a valid

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Wet-Chemical Approaches for Atomic Layer Etching of Semiconductors: Surface Chemistry, Oxide Removal and Reoxidation of InAs (100)

The use of sacrificial self-assembled monolayers (SAMs) to prepare clean n-type GaAs (100) surfaces without band bending in vacuo is demonstrated. GaAs surface passivation using octadecanethiol SAMs after HCl cleaning is shown to lead to an enhancement of the room-temperature photoluminescence intensity. Synchrotron-radiation photoelectron spectroscopy (SRPES) finds that the interfacial oxide between GaAs and the SAM remains below the detection limit. Evidence for both Ga–S and As–S bonds at the GaAs–thiolate interface is found. The limited thermal stability of the SAM allows the desorption of the alkyl chains by in situ thermal annealing at temperatures above 180 °C, leaving S bonded to Ga behind. The resulting surface contains only a very small amount of O (0.05 ML coverage) and C (about 3% of the SAM remaining) and shows no band bending with the surface Fermi level close to the conduction band. Atomic layer deposition of Al2O3 on this surface occurs via the formation of Al–S bonds without introducing a...

Dennis H. van Dorp

Papers

SiC: A Photocathode for Water Splitting and Hydrogen Storage

Electrochemical photodegradation study of semiconductor pigments : influence of environmental parameters

Wet-Chemical Approaches for Atomic Layer Etching of Semiconductors: Surface Chemistry, Oxide Removal and Reoxidation of InAs (100)

Sacrificial Self-Assembled Monolayers for the Passivation of GaAs (100) Surfaces and Interfaces

Nanoscale Etching of In0.53Ga0.47As in H2O2/HCl Solutions for Advanced CMOS Processing