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41.
Molecular Engineering of Push–Pull Porphyrin Dyes for Highly Efficient Dye‐Sensitized Solar Cells: The Role of Benzene Spacers 下载免费PDF全文
Shaik M. Zakeeruddin Shu‐Nung Chang Chi‐Hung Hsieh Chen‐Yu Yeh Michael Grätzel 《Angewandte Chemie (International ed. in English)》2014,53(11):2973-2977
Porphyrins have drawn much attention as sensitizers owing to the large absorption coefficients of their Soret and Q bands in the visible region. In a donor and acceptor zinc porphyrin we applied a new strategy of introducing 2,1,3‐benzothiadiazole (BTD) as a π‐conjugated linker between the anchoring group and the porphyrin chromophore to broaden the absorption spectra to fill the valley between the Soret and Q bands. With this novel approach, we observed 12.75 % power‐conversion efficiency under simulated one‐sun illumination (AM1.5G, 100 mW cm?2). In this study, we showed the importance of introducing the phenyl group as a spacer between the BTD and the zinc porphyrin in achieving high power‐conversion efficiencies. Time‐resolved fluorescence, transient‐photocurrent‐decay, and transient‐photovoltage‐decay measurements were employed to determine the electron‐injection dynamics and the lifetime of the photogenerated charge carriers. 相似文献
42.
Stereoelectronic Basis for the Kinetic Resolution of N‐Heterocycles with Chiral Acylating Reagents 下载免费PDF全文
Sheng‐Ying Hsieh Benedikt Wanner Dr. Philip Wheeler Prof. Dr. André M. Beauchemin Prof. Dr. Tomislav Rovis Prof. Dr. Jeffrey W. Bode 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(24):7228-7231
The kinetic resolution of N‐heterocycles with chiral acylating agents reveals a previously unrecognized stereoelectronic effect in amine acylation. Combined with a new achiral hydroxamate, this effect makes possible the resolution of various N‐heterocycles by using easily prepared reagents. A transition‐state model to rationalize the stereochemical outcome of this kinetic resolution is also proposed. 相似文献
43.
Nanocomposites of Tantalum‐Based Pyrochlore and Indium Hydroxide Showing High and Stable Photocatalytic Activities for Overall Water Splitting and Carbon Dioxide Reduction 下载免费PDF全文
Meng‐Chun Hsieh Guan‐Chang Wu Dr. Wei‐Guang Liu Prof. William A. Goddard III Prof. Dr. Chia‐Min Yang 《Angewandte Chemie (International ed. in English)》2014,53(51):14216-14220
Nanocomposites of tantalum‐based pyrochlore nanoparticles and indium hydroxide were prepared by a hydrothermal process for UV‐driven photocatalytic reactions including overall water splitting, hydrogen production from photoreforming of methanol, and CO2 reduction with water to produce CO. The best catalyst was more than 20 times more active than sodium tantalate in overall water splitting and 3 times more active than Degussa P25 TiO2 in CO2 reduction. Moreover, the catalyst was very stable while generating stoichiometric products of H2 (or CO) and O2 throughout long‐term photocatalytic reactions. After the removal of In(OH)3, the pyrochlore nanoparticles remained highly active for H2 production from pure water and aqueous methanol solution. Both experimental studies and density functional theory calculations suggest that the pyrochlore nanoparticles catalyzed the water reduction to produce H2, whereas In(OH)3 was the major active component for water oxidation to produce O2. 相似文献
44.
We report on the fabrication of a surface‐enhanced Raman scattering (SERS) platform, comprised of a three‐dimensional (3D) porous eggshell membrane (ESM) scaffold decorated with Ag nanoparticles (NPs). Both native and treated ESM were used, where the treated ESM pore size and fiber crossing density was controlled by timed exposure to hydrogen peroxide (H2O2). Ag NPs were synthesized in situ by reduction of silver nitrate with ascorbic acid. Our results demonstrate that H2O2‐treated Ag‐ESM provides a more densely packed 3D network of active material, which leads to consistently higher SERS enhancement than untreated Ag‐ESM substrates. 相似文献
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We described a simple and quick miniaturized sequencing gel system for DNA analysis. Two major modifications were made to the previously reported miniaturized DNA sequencing gel system to achieve high-resolution hydroxyl radical cleavage analysis: including formamide in the miniaturized gel and providing uniform heating during electrophoresis. Our method enables one to reduce the cost for chemicals and to significantly reduce electrophoresis time. Furthermore, minimal gel handling simplifies the entire process. We show that the resolution of DNA fragments obtained by hydroxyl radical cleavage for the miniaturized gel is similar to that of a large conventional sequencing gel. 相似文献
47.
Hweiyan Tsai Hsiao-Ching Hu Chih-Chung Hsieh Yi-Hsuan Lu Chien-Hong Chen Chwan-Bor Fuh 《中国化学会会志》2020,67(1):152-159
Chloramphenicol (CAP) is a veterinary antibiotic that has been banned due to its severe side effects in humans. Through the application of manure, veterinary antibiotics can enter the soil, where they can be taken up by crops and vegetables and pose a potential health hazard to humans. Thus, it is highly desirable to develop a rapid and sensitive tool for on-site detection of CAP to ensure food safety and to control the abuse of antibiotics. To this end, nitrogen-doped graphene quantum dots (N-GQDs) were successfully prepared via microwave-assisted synthesis using citric acid and urea as carbon and nitrogen sources, respectively. Analytical results suggested that the interaction between N-GQDs and CAP could occurs via π-π stacking, which quenched N-GQD fluorescence. CAP spiked into chicken feed could be rapidly extracted with ethanol and quantified based on N-GQD fluorescence quenching without further separation. This method showed good recovery (97–102.6%), a low detection limit (1.8 ppm), and was not affected by interference from florfenicol, and thiamphenicol, legal substitute antibiotics. This method has excellent potential for determination of CAP in livestock feed and soil. 相似文献
48.
Analysis of the pharmacokinetics and metabolism of aloe‐emodin following intravenous and oral administrations in rats 下载免费PDF全文
Hui‐Ju Lin Yow‐Wen Hsieh Shiuan‐Pey Lin Yu‐Chi Hou 《Biomedical chromatography : BMC》2016,30(10):1641-1647
Aloe‐emodin, a natural polyphenolic anthraquinone, has shown various beneficial bioactivities in vitro. The aim of this study was to investigate the pharmacokinetics and metabolism of aloe‐emodin. Aloe‐emodin was intravenously and orally administered to rats. The concentrations of aloe‐emodin and rhein, a metabolite of aloe‐emodin, were determined by HPLC method prior to and after hydrolysis with β‐glucuronidase and sulfatase/β‐glucuronidase. The results showed that the systemic exposures of aloe‐emodin and its metabolites were ranked as aloe‐emodin glucuronides (G) > rhein sulfates (S) > aloe‐emodin > rhein and rhein G when aloe‐emodin was given intravenously. In contrast, when aloe‐emodin was administered orally, the parent form of aloe‐emodin was not absorbed per se, and the systemic exposures of its metabolites were ranked as aloe‐emodin G > rhein G > rhein. In conclusion, the metabolites of aloe‐emodin are more important than the parent form for the bioactivities in vivo. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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50.
W.N Hsieh 《Journal of Combinatorial Theory, Series A》1975,18(3):252-261
The following theorem is proved. It is a generalization of the problem for finite vector spaces analogous to a theorem of Kleitman for finite sets.Let V be an n-dimensional vector space over a finite field F of q elements. Suppose we have two collections, one consisting of k- and the other of m-dimensional subspaces of V with the property that the intersection of each member of one with each member of the other has dimension no less than r.Then if n ? k + m + 2 or n ? k + m + 1 and q ? 3, there are either no more than members in the first family or fewer than members in the second.The method used leads to a similar result for sets, provided that n ? r + (r + 1)(k ? r)(m ? r + 1) with k ? m. 相似文献