438 research outputs found
Dataset for Giant enhancement of cathodoluminescence of monolayer transitional metal dichalcogenides semiconductors
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Zheng, S., So, J-K., Liu, F., Liu, Z., Zheludev, N., & Fan, H. J. (2017). Giant enhancement of cathodoluminescence of monolayer transitional metal dichalcogenides semiconductors. Nano Letters, 17(10), 6475-6480. DOI: 10.1021/acs.nanolett.7b03585</span
An investigation into catalysts to improve the low temperature performance of an SCR
No full textSelective catalytic reduction with NH3 is considered as one of the most effective technologies controlling NOx emission. Metal Fe based catalysts were used in the investigation to improve the low temperature performance of NOx conversion. The temperature range studied was between 150 degrees C and 350 degrees C with the interval of 50 degrees C. The honeycomb catalysts were prepared by an impregnation method. The study also included characterization of catalysts by BET, XRD, H2-TPR, SEM and XPS methods. It is found an increase in metal Fe content from 2 to 6 % wt. offers an improvement in the catalytic performance. However, a further increment in Fe content will result in a decrease in its performance. More than 90 % NOx conversion rate could be achieved over the Fe-based honeycomb catalyst at a low temperature by doping with Ni and Zr metal with different weights. Among all the catalysts studied, the mixed metal catalyst of Fe-Ni-Zr is found the most potential one, not only because of its higher NOx conversion rate at a low temperature, but also because of its wider operation temperature window. The effect of gas hourly space velocity (GHSV) was also investigated in the study and results show as GHSV increases that reduction of NOx is decreased
Enhanced luminescence of MoS<sub>2</sub>, WS<sub>2</sub> and WSe<sub>2</sub>, direct band gap semiconductor heterostructures
No full textWe introduce van der Waals heterostructures to amplify the otherwise negligible cathodoluminescence from monolayer transition metal dichalcogenides, which allowed to visualize the nanoscale variation of strain and photonic modes in the monolayer on engineered surfaces
Giant enhancement of cathodoluminescence of monolayer transitional metal dichalcogenides semiconductors
No full textMonolayer two-dimensional transitional metal dichalcogenides, such as MoS2, WS2, and WSe2, are direct band gap semiconductors with large exciton binding energy. They attract growing attentions for optoelectronic applications including solar cells, photodetectors, light-emitting diodes and phototransistors, capacitive energy storage, photodynamic cancer therapy, and sensing on flexible platforms. While light-induced luminescence has been widely studied, luminescence induced by injection of free electrons could promise another important applications of these new materials. However, cathodoluminescence is inefficient due to the low cross-section of the electron–hole creating process in the monolayers. Here for the first time we show that cathodoluminescence of monolayer chalcogenide semiconductors can be evidently observed in a van der Waals heterostructure when the monolayer semiconductor is sandwiched between layers of hexagonal boron nitride (hBN) with higher energy gap. The emission intensity shows a strong dependence on the thicknesses of surrounding layers and the enhancement factor is more than 500-fold. Strain-induced exciton peak shift in the suspended heterostructure is also investigated by the cathodoluminescence spectroscopy. Our results demonstrate that MoS2, WS2, and WSe2 could be promising cathodoluminescent materials for applications in single-photon emitters, high-energy particle detectors, transmission electron microscope displays, surface-conduction electron-emitter, and field emission display technologies
A Historical Study on Utsunomiya Tokuma's Thought : Focusing upon Postwar Period ofWorld War II until 1949, His Launch into Politics
No full text宇都宮徳馬は, 第二次世界大戦後, 外交問題を中心に活躍し, 日ソ・日中・日朝国交回復に尽力し, 保守政治家の中でも数少ないリベラリストとして知られる. しかし, 彼は戦前に日本共産党に加入し, 「転向」をへて, 企業を営みながら官僚統制批判の言論活動に従事したという, 異色の知識人・自由主義思想家でもあった. このように日本の知識人の「政治」や「社会主義」, 「平和」に対する一つの特徴を示す存在である宇都宮について, 従来日本では, 一次資料にもとづく充分な検討がなされてこなかった. ことに, 戦後における彼の活動について, 思想史的な追及は不充分である. こうした研究状況を踏まえ, 本稿は戦後から1949年政界進出にいたるまでの宇都宮の思想と行動に焦点をあて, 戦前・戦中における官僚統制や軍部独裁への批判との連続性を意識しつつ, 戦後における彼の思想的立場, とりわけ戦後経済再建に関わる政策論の特徴とその史的位置を確認する.Utsunomiya Tokuma is known as one of the outstanding liberalists among Japanese conservative politicians, who devoted himself to diplomacy to restore foreign relations between Japan and communist nations such as the Soviet Union, China and North Korea. He also was a unique liberal intellectual who, once having joined the Japanese Communist Party before the Second World War, going through "conversion" from communism, got engaged in business activity while developing public criticism on bureaucracy-controlled politics. Although such a pass of thoughts of Utsunomiya might be viewed as typical of Japanese intelectuals towards politics, socialism as well as the ideal of peace, only few reviews based on primary sources have attempted so far. In particular, studies on his postwar activities are scarce. On the basis of this understanding, Utsunomiyaʼs thoughts and acrivities from the end ofWWII through his political commitment to the congress in 1949 are examined in this paper. Special attentions are paid to his policical view of the post-war reconstruction of Japanese ecomony and its historical uniquness, while taking in consideration his criticism in the pre-war period onto the bureaucratism and dominance of military in Japanese government
Efficient picosecond x-ray pulse generation from plasmas in the radiation dominated regime
No full textThe efficient conversion of optical laser light into bright ultrafast x-ray pulses in laser created plasmas is of high interest for dense plasma physics studies, material science, and other fields. However, the rapid hydrodynamic expansion that cools hot plasmas has limited the x-ray conversion efficiency (CE) to 1% or less. Here we demonstrate more than one order of magnitude increase in picosecond x-ray CE by tailoring near solid density plasmas to achieve a large radiative to hydrodynamic energy loss rate ratio, leading into a radiation loss dominated plasma regime. A record 20% CE into ℎ>1 keVhν>1 keV photons was measured in arrays of large aspect ratio Au nanowires heated to keV temperatures with ultrahigh contrast femtosecond laser pulses of relativistic intensity. The potential of these bright ultrafast x-ray point sources for table-top imaging is illustrated with single shot flash radiographs obtained using low laser pulse energy. These results will enable the deployment of brighter laser driven x-ray sources at both compact and large laser facilities.Fil: Hollinger, Reed. Department Of Electrical And Engineering;Fil: Bargsten, Clayton. Department Of Electrical And Engineering;Fil: Shlyaptsev, Vyacheslav N.. Department Of Electrical And Engineering;Fil: Kaymak, Vural. Institut Fur Theoretische Physik, Heinrich-heine-univer;Fil: Pukhov, Alexander. Heinrich-heine-universität Düsseldorf;Fil: Capeluto, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Wang, Shoujun. Department Of Electrical And Engineering;Fil: Rockwood, Alex. Department Of Electrical And Engineering;Fil: Wang, Yong. Department Of Electrical And Engineering;Fil: Townsend, Amanda. Department Of Electrical And Engineering;Fil: Prieto, Amy. Department Of Electrical And Engineering;Fil: Stockton, Patrick. Department Of Electrical And Engineering;Fil: Curtis, Alden. Department Of Electrical And Engineering;Fil: Rocca, Jorge J.. Department Of Electrical And Engineering
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