52 research outputs found
Graphene: Microwave Enabled One‐Pot, One‐Step Fabrication and Nitrogen Doping of Holey Graphene Oxide for Catalytic Applications (Small 27/2015)
No full textPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112226/1/smll201570159.pd
Organic-inorganic hybrid solar cells via electropolymerization
No full textIntegrating polymers with inorganic nanostructures is difficult due to wetting and surface energy considerations. We developed an electropolymerization method to grow conformal polymers on high aspect ratio nanostructures. Our method is shown to improve the polymer filling rate inside the nanostructures and can be used in the development of efficient hybrid solar cells. As an example, we have studied the hybrid system of electropolymerized polythiophene (e-PT) on a variety of conductive (Au and ITO) and semiconductive substrates (Si, Ge, ZnO). In particular, e-PT/ZnO hybrid structure can be further developed into organic photovoltaics (OPV). Although unsubstituted PT is not the ideal polymer material for high efficiency solar cells, it is an excellent choice for studying basic bonding and morphology in hybrid structures. We find that e-PT is covalently bound to the polar ZnO planar substrate via a Zn-S bond, adopting an upright geometry. By contrast, no strong covalent bonding was observed between e-PT and ZnO nanorods that consist of non-polar ZnO surfaces predominantly. Energy level alignment at interfaces is critical for fundamental understanding and optimization of OPV as band offsets of the donor and acceptor materials largely determine the open circuit voltage (Voc) of the device. Using ultraviolet photoemission spectroscopy (UPS) and inverse photoemission spectroscopy (IPS), we examined the correlation between energy alignment and photovoltaic properties of a model hybrid solar cell structure incorporating undoped electrodeposited polythiophene (e-PT) films on ZnO planar substrates. The electrolyte anion (BF4-, PF6-, ClO4- or CF3SO3-) used in the electrodeposition solution was found to exert a strong influence on the neutral e-PT film morphology and adhesion, the band alignment at the interface, and ultimately the photovoltaic behavior. The interfacial dipole lowers polythiophene energy levels, increasing the theoretical and actual Voc in polythiophene/ZnO photovoltaics. Our electropolymerization approach to integrate the organic and inorganic phases aims at understanding the chemistry at the interface, and the electronic and morphological properties of the system. This work should be generally applicable to other conjugated polymers and nanostructures, and it contributes to an understanding of organic-inorganic interfaces and electronic structures that may be advantageous to a range of electronic/photonic applications.Ph. D.Includes bibliographical referencesby Wenchun Fen
Qianlong zao qi guan fang yi shi xing tai yu shi wen lun de jiu ge: "Yu xuan Tang Song wen chun", "Yu xuan Tang Song shi chun" yan jiu = The entanglement between official ideology and literary critics in early Qianlong period : a study on Imperial anthology of essays of the Tang and Song periods and Imperial anthology of poems of the Tang and Song periods
No full textM.Phil.While Early Qing emperors placed great importance on cultural policies, the Qianlong Emperor was particularly keen on the compilations of canonical texts. Two such examples are Imperial Anthology of Essays of the Tang and Song Periods御選唐宋文醇 (Yuxuan Tang-Song Wenchun) (hereafter Wenchun) and Imperial Anthology of Poems of the Tang and Song Periods御選唐宋詩醇 (Yuxuan Tang-Song Shichun) (hereafter Shichun). These significant official literary collections were highly valued by the Hanlin翰林 academicians and were assigned as curriculum in imperial examinations, with wide readership ranging from the official elites to the general public. As the compilations of Wenchun and Shichun were attributed to Emperor Qianlong himself, the innate literary perspectives inevitably reflected the official ideologies and should not be regarded as ordinary compilations in the history of Chinese literature.This thesis focuses on how the Qianlong Emperor and the official compilers interpreted Wenchun and Shichun from political perspectives in order to promote the official ideologies. With the aid of the field theory first proposed by Pierre Bourdieu, this thesis examines the role of the Qianlong Emperor in the literary and political fields, and the ways he manipulated the anthologies as political tools to advance his agenda.This thesis first provides a literature review, purpose and methodology of research, followed by explanations of Wenchun and Shichun’s structures, circulation and editions, with especial attention to the political environment of Early Qianlong period. Through a close analysis of Wenchun and Shichun’s selection of works and critiques, the political ideologies involved such as loyalty, Hua-yi distinction 華夷之辨 (Sino-Barbarian Dichotomy) and the factional strife of reform and conservative parties of the Northern Song Period, this thesis states the emperor and his official compilers’ intention to establish gonglun公論 (universal opinion) through the compilations. Finally, in order to pinpoint the influence of official anthologies, a comparison of Shichunand two private anthologies by Shen Deqian 沈德潛 , Anthology of Tang Poems 唐詩別裁集 (Tangshi Biecaiji) and Selected Poems from Three Song and Jin Period Poets宋金三家詩選 (SongJin Sanjia Shixuan) is also included.清初君主重視漢人文化，因而 衍生了 一系列文化政策 其中乾隆帝尤其熱衷於修纂書籍， 《御選唐宋文醇》、《御選唐宋詩醇》（下簡稱《文醇》、《詩醇》） 便屬 其 早年御選的兩部重要 官方 選本。二書刊成之後，深受大量翰林學士重視，更曾 成為科舉策問的 試題 內容 ，可見二書影響力並不僅限於涉足官場的上層知識份子，普通士子亦須 對二書 有所掌握。 作為官方選本， 《文醇》、《詩醇》 具有特殊的意義 ，書中所表現的文學觀包含 著濃厚的 官方意識形態，因此不能單純以普通文學選集目之。本文旨在考察乾隆帝及其編選大臣如何從政治的角度詮釋《文醇》與《詩醇》，以達到文學以外的目的，即從中滲透官方的意識形態。本文借用法國社會學家布迪厄（ Pierre Bourdieu）的「場域」 Field）理論，討論乾隆帝在「文藝場域」與「政治場域」之中所扮演的角色，以及他如何運用權力，把《文醇》與《詩醇》化為政治上的工具。本文首先回顧前人對《文醇》、《詩醇》的研究，並說明本文的研究目的與方法，繼而 簡述 《文醇》、《詩醇》的體例、流傳及版本，並簡述乾隆帝早年所面對的政治環境，以及其政治心態與二書之間的關係。本文透過觀察二書中的選評，總論二書的政教元素，例如二書對於儒家詩學的詮釋，提倡尚用文論、士大夫精神的道德教化、以文學為諫諍的方法等。 進而 ，本文以忠義、華夷、北宋新舊黨爭等案例，討論乾隆官方如何透過《文醇 》、《詩醇》建構文學 與 歷史的「公論」。最後，本文比較《詩醇》與沈德潛的《唐詩別裁集》、《宋金三家詩選》，藉以體現文人自編選本如何受到官方詩選的影響，而在評選文學時不免滲入政治意識形態。周嘉俊."2020年8月".Parallel title from English abstract.Thesis M.Phil. Chinese University of Hong Kong 2020.Includes bibliographical references (leaves 128-136).Abstract also in English.Title from PDF title page (viewed on March 10, 2022).Zhou Jiajun
Re-examination of the seasonality of suicide in Taiwan during 1991–2008: A population-based study
No full textComparison of the Effect of Pruning on Plant Growth and Transcriptome Profiles in Different Tea Varieties
No full textAlthough pruning contributes to the growth and development of new shoots, it is important to note that the growth potential and yield of tea varieties may differ after pruning due to genetic and environmental factors. In this experiment, 20 different varieties of tea plants were used to observe their potential for growth, shoot development, and other phenotypic indexes after pruning. The study aimed to determine the suitability of each variety for heavy pruning. It was concluded that there were obvious differences in tree strength and new growth after pruning of the different varieties, with ‘Zhongcha 302’ exhibiting the strongest growth and ‘Emei Wenchun’ showing the weakest growth. In order to understand the molecular mechanisms involved, a transcriptomic analysis was carried out on the two tea varieties. The results of the data indicate that the expression of CYP450 family was high in ‘Zhongcha 302’. In ‘Emei Wenchun’, the expression of NCED was higher than that in ‘Zhongcha 302’. The KEGG results indicate that pruning stimulates the expression of genes involved in phytohormone signalling and plant–pathogen interaction pathways in tea plants. The study offered scientific guidance for tea plant pruning suitability and preliminarily revealed the regulatory mechanism of new shoot growth in different tea plant varieties at the transcriptome level
The secular trend of suicide rate and the socio-economic, media, and climatic factors in Taiwan, 1976–2009: A population-based study
No full textInterpretable and Efficient Interferometric Contrast in Scanning Transmission Electron Microscopy with a Diffraction-Grating Beam Splitter
No full textEfficient imaging of biomolecules, two-dimensional materials, and electromagnetic fields depends on retrieval of the phase of transmitted electrons. We demonstrate a method to measure phase in a scanning transmission electron microscope (STEM) using a nanofabricated diffraction grating to produce multiple probe beams. The measured phase is more interpretable than phase-contrast scanning transmission electron microscopy techniques without an off-axis reference wave, and the resolution could surpass that of off-axis electron holography. We apply this technique, called STEM holography, to image nanoparticles, carbon substrates, and electric fields. The contrast observed in experiments agrees well with contrast predicted in simulations
Physical Body Impact After High Altitude Bail-out
No full textAbstractIn most of the emergency circumstances, the aircrew leaves the aircraft under unsatisfied conditions, such as too high relative velocity to the ambient air or low partial oxygen pressure. The aircrew must pass through this area as quickly as possible before opening the parachute safely, viz., free-fall. Numerical simulations are conducted in this paper to explore the major characteristics of the aircrew free-fall process by using a commercial computational fluid dynamic (CFD) software, FLUENT. Coupled with the classical pressure-altitude and temperature-altitude relations, Navier-Stokes (N-S) equations for compressible flow are solved by using finite volume method. The body velocity and the attitude are predicted with six-degree of freedom (6DOF) module. The evolution of velocities, including horizontal, vertical components and angular velocity, is obtained. It is also analyzed further according to the particle kinetic theories. It is validated that the theories can predict the process qualitatively well with a modified drag effect, which mainly stems from the velocity pressure. An empirical modification factor is proposed according to the fitting results
Optimization study on multicolumn envelope meshing pair of single screw compressor based on leakage characteristics
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