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

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Fujishima and Honda (1972) demonstrated the potential of titanium dioxide (TiO2) semiconductor materials to split water into hydrogen and oxygen in a photo-electrochemical cell. Their work triggered the development of semiconductor photocatalysis for a wide range of environmental and energy applications. One of the most significant scientific and commercial advances to date has been the development of visible light active (VLA) TiO2 photocatalytic materials. In this review, a background on TiO2 structure, properties and electronic properties in photocatalysis is presented. The development of different strategies to modify TiO2 for the utilization of visible light, including non metal and/or metal doping, dye sensitization and coupling semiconductors are discussed. Emphasis is given to the origin of visible light absorption and the reactive oxygen species generated, deduced by physicochemical and photoelectrochemical methods. Various applications of VLA TiO2, in terms of environmental remediation and in particular water treatment, disinfection and air purification, are illustrated. Comprehensive studies on the photocatalytic degradation of contaminants of emerging concern, including endocrine disrupting compounds, pharmaceuticals, pesticides, cyanotoxins and volatile organic compounds, with VLA TiO2 are discussed and compared to conventional UV-activated TiO2 nanomaterials. Recent advances in bacterial disinfection using VLA TiO2 are also reviewed. Issues concerning test protocols for real visible light activity and photocatalytic efficiencies with different light sources have been highlighted.

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A review on the visible light active titanium dioxide photocatalysts for environmental applications

The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

This review paper encompasses a detailed study of semiconductor metal oxide (SMO) gas sensors. It provides for a detailed comparison of SMO gas sensors with other gas sensors, especially for ammonia gas sensing. Different parameters which affect the performance (sensitivity, selectivity and stability) of SMO gas sensors are discussed here under. This paper also gives an insight about the dopant or impurity induced variations in the SMO materials used for gas sensing. It is concluded that dopants enhance the properties of SMOs for gas sensing applications by changing their microstructure and morphology, activation energy, electronic structure or band gap of the metal oxides. In some cases, dopants create defects in SMOs by generating oxygen vacancy or by forming solid solutions. These defects enhance the gas sensing properties. Different nanostructures (nanowires, nanotubes, heterojunctions), other than nanopowders have also been studied in this review. At the end, examples of SMOs are given to illustrate the potential use of different SMO materials for gas sensing.

Semiconductor metal oxide gas sensors: A review

A three-stage thermopnuematic peristaltic micropump for controlling micro to nano litters of fluid was simply designed and fabricated from PDMS on glass slide. Pump structure consists of inlet and outlet, microchannel, three thermopneumatic actuations, and three heaters. In microchannel, fluid is controlled and pumped by peristaltic motion of actuation diaphragm. Actuation diaphragm can bend up and down by exploiting expanded air that induced by increasing heater temperature. The motion of fluid in nanoport was captured by digital camera every 5 minutes, and then the flow rate was monitored from height difference of fluid in nanoport by consecutive records. The optimum flow rate is 0.82 mul/min (=13.6 nl/sec) with applying 14 volts three-phase input driving voltage at frequency of 0.033 Hz.

A three-stage thermopneumatic peristaltic micropump for PDMS-based micro/nanofluidic systems

An investigation of the influence of organic vapor (ethanol, methanol and acetone) on the characteristics of simple-structure sensors fabricated from single-walled carbon nanotube (SWCNT) thin films is reported. SWCNTs were directly deposited, by using atmospheric pressure CVD using alcohol-ferrocene mist, on the patterned Al electrodes to fabricate a sensor. It was found that the characteristic of SWCNT-based sensors depended on the depositing position in CVD reactor. The sensor response could be optimized by adjusting the depositing position along the inner quartz reactor. The sensor reproducibility could be improved by light soaking after switching to air.

Organic Vaporensors Based on Single-walled CNTs

In this work, we report the conversion of carbon dioxide (CO2) gas into graphene on copper foil by using a thermal chemical vapor deposition (CVD) method assisted by hydrogen (H2) plasma pre-treatment. The synthesized graphene has been characterized by Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results show the controllable number of layers (two to six layers) of high-quality graphene by adjusting H2 plasma pre-treatment powers (100–400 W). The number of layers is reduced with increasing H2 plasma pre-treatment powers due to the direct modification of metal catalyst surfaces. Bilayer graphene can be well grown with H2 plasma pre-treatment powers of 400 W while few-layer graphene has been successfully formed under H2 plasma pre-treatment powers ranging from 100 to 300 W. The formation mechanism is highlighted.

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Conversion of Carbon Dioxide into Chemical Vapor Deposited Graphene with Controllable Number of Layers via Hydrogen Plasma Pre-Treatment

The electrical conductivity and capacitive behavior of supercapacitors (SCs) were found to be improved by the synergistic effects of the violet laser treatment (VLT) of nitrogen-doped reduced graphene oxide (N-rGO) as an electrode and 1.5% (w/v) p-phenylenediamine (PPD)-containing KOH as a redox electrolyte. The SC employing VLT treatment on the N-rGO electrode with 2 M KOH (N-rGO-V) represented a greater specific capacitance of up to 263.6 F g–1 compared to N-rGO in the same electrolyte, which was 232.2 F g–1 at 0.25 A g–1. To further improve the charge-storage ability, the SC using the VLT treatment on the N-rGO electrode with the PPD addition into 2 M KOH (N-rGO-V-PPD) revealed the highest specific capacitance, reaching 593.7 F g–1 at 0.25 A g–1 or 28.6% compared to N-rGO in the same redox electrolyte (N-rGO-PPD). Furthermore, the capacitance retention after 10,000 cycles of N-rGO-V-PPD remained at 62% (265 F g–1 at 100 mV s–1), which is still significantly higher than that of other samples, and the VLT technique provided a lower self-discharge rate. According to the physical characterizations, N-rGO-V-PPD has a rougher and larger surface area due to the exfoliated graphene oxide sheets and has a modest increase in the number of quinone/carbonyl functional groups in the graphene material, resulting in better electrical conductivity. All of these could be contributing factors to the performance improvement. Lastly, PPD provides redox mediators such as H+ and e– in the redox electrolyte, which are anticipated to improve the charge storage. 

Violet Laser Treatment of Nitrogen-Doped Reduced Graphene Oxide Electrodes and KOH Electrolytes Containing p-Phenylenediamine for High-Performance Supercapacitors

Adisorn Tuantranont

Papers

A three-stage thermopneumatic peristaltic micropump for PDMS-based micro/nanofluidic systems

Organic Vaporensors Based on Single-walled CNTs

Conversion of Carbon Dioxide into Chemical Vapor Deposited Graphene with Controllable Number of Layers via Hydrogen Plasma Pre-Treatment

Violet Laser Treatment of Nitrogen-Doped Reduced Graphene Oxide Electrodes and KOH Electrolytes Containing p-Phenylenediamine for High-Performance Supercapacitors

Effect of PdO-PdO2 core-shell nanocatalysts on hydrogen sensing performances of flame-made spinel Zn2SnO4 nanoparticles