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71.
Seon‐Kyoung Son Yoon‐Suk Choi Woo‐Hyung Lee Yongtaek Hong Jae‐Ryoung Kim Won‐Suk Shin Sang‐Jin Moon Do‐Hoon Hwang In‐Nam Kang 《Journal of polymer science. Part A, Polymer chemistry》2010,48(3):635-646
A series of new phenothiazylene vinylene‐based semiconducting polymers, poly[3,7‐(4′‐dodecyloxyphenyl)phenothiazylene vinylene] ( P1 ), poly[3,7‐(4′‐dodecyloxyphenyl)phenothiazylene vinylene‐alt‐1,4‐phenylene vinylene] ( P2 ), and poly[3,7‐(4′‐dodecyloxyphenyl)phenothiazylene vinylene‐alt‐2,5‐thienylene vinylene] ( P3 ), have been synthesized via a Horner‐Emmons reaction. FTIR and 1H NMR spectroscopies confirmed that the configurations of the vinylene groups in the polymers were all‐trans (E). The weight‐averaged molecular weights (Mw) of P1 , P2 , and P3 were found to be 27,000, 22,000, and 29,000, with polydispersity indices of 1.91, 2.05, and 2.25, respectively. The thermograms for P1 , P2 , and P3 each contained only a broad glass transition, at 129, 167, and 155 °C, respectively, without the observation of melting features. UV–visible absorption spectra of the polymers showed two strong absorption bands in the ranges 315–370 nm and 450–500 nm, which arose from absorptions of the phenothiazine segments and the conjugated main chains. Solution‐processed field‐effect transistors fabricated from these polymers showed p‐type organic thin‐film transistor characteristics. The field‐effect mobilities of P1 , P2 , and P3 were measured to be 1.0 × 10?4, 3.6 × 10?5, and 1.0 × 10?3 cm2 V?1 s?1, respectively, and the on/off ratios were in the order of 102 for P1 and P2 , and 103 for P3 . Atomic force microscopy and X‐ray diffraction analysis of thin films of the polymers show that they have amorphous structures. A photovoltaic device in which a P3 /PC71BM (1/5) blend film was used as the active layer exhibited an open‐circuit voltage (VOC) of 0.42 V, a short circuit current (JSC) of 5.17 mA cm?2, a fill factor of 0.35, and a power conversion efficiency of 0.76% under AM 1.5 G (100 mW cm?2) illumination. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 635–646, 2010 相似文献
72.
Li (lithium) isotope analysis using MC-ICP-MS is a very powerful tracer measurement method. This is widely used for identification of Li isotopes in many fields of study. This useful method, however, has an effect on the natural Li isotope background. This is impacted by the instrument matrix. In this study, we show that the MC-ICP-MS condition is characterized by both a low baseline background and a high-sensitivity distance at Ar plasma condition. In addition, the Li isotope ratio was measured by the use of experimental conditions that were superior to both the general plasma condition and those used in other studies. The samples were subjected to both acid leaching and a cation exchange resin (Bio-Rad AG 50 W-X8 200–400 mesh) modified for seawater samples. The isotope variations were corrected using the bracket method, the measured Li isotope ratio of sample, and the mean ratios of the L-SVEC standard (NIST L-SVEC Li2CO3) measured before and after the sample run. The isotope variation was presented as the deviation (per mil) of the measured ratio from that of the recommended value. 相似文献
73.
The present study investigates the convective heat/mass transfer and pressure drop characteristics in a rotating two-pass
duct with and without transverse ribs. The Reynolds number based on the hydraulic diameter is kept constant at 10,000 and
the rotation number is varied from 0.0 to 0.2. When rib turbulators are installed, heat/mass transfer and friction loss are
respectively augmented 2.5 times and 5.8 times higher than those of the smooth duct since the main flow is turbulated by reattaching
and separating on the vicinity of the duct surfaces. Differences of heat/mass transfer and pressure coefficient between leading
and trailing surfaces result from the rotation of duct, so that Sherwood number ratios and pressure coefficients are high
on the trailing surface in the first-pass and on the leading surface in the second-pass. In the turning region, a pair of
Dean vortices shown in the stationary case transform into one large asymmetric vortex cell, and subsequently heat/mass transfer
and pressure drop characteristics also change. As the rotation number increases, the discrepancies of the heat/mass transfer
and the pressure coefficient enlarge between the leading and trailing surfaces. 相似文献
74.
Hyewon Ryoo Hyung Bin Bae Dr. Young‐Min Kim Dr. Jin‐Gyu Kim Dr. Seongsu Lee Prof. Sung‐Yoon Chung 《Angewandte Chemie (International ed. in English)》2015,54(27):7963-7967
Using spinel‐type Li(Mn1.5Ni0.5)O4 with two different cations, Mn and Ni, in the oxygen octahedra as a model system, we show that a cation ordering transition takes place through the formation of Frenkel‐type point defects. A series of experimental results based on atomic‐scale observations and in situ powder diffractions along with ab initio calculations consistently support such defect‐mediated transition behavior. In addition to providing a precise suggestion of the intermediate transient states and the resulting kinetic pathway during the transition between two phases, our findings emphasize the significant role of point defects in ordering transformation of complex oxides. 相似文献
75.
Metal‐Doped Nitrogenated Carbon as an Efficient Catalyst for Direct CO2 Electroreduction to CO and Hydrocarbons 下载免费PDF全文
Dr. Ana Sofia Varela Dr. Nastaran Ranjbar Sahraie Julian Steinberg Wen Ju Dr. Hyung‐Suk Oh Prof. Dr. Peter Strasser 《Angewandte Chemie (International ed. in English)》2015,54(37):10758-10762
This study explores the kinetics, mechanism, and active sites of the CO2 electroreduction reaction (CO2RR) to syngas and hydrocarbons on a class of functionalized solid carbon‐based catalysts. Commercial carbon blacks were functionalized with nitrogen and Fe and/or Mn ions using pyrolysis and acid leaching. The resulting solid powder catalysts were found to be active and highly CO selective electrocatalysts in the electroreduction of CO2 to CO/H2 mixtures outperforming a low‐area polycrystalline gold benchmark. Unspecific with respect to the nature of the metal, CO production is believed to occur on nitrogen functionalities in competition with hydrogen evolution. Evidence is provided that sufficiently strong interaction between CO and the metal enables the protonation of CO and the formation of hydrocarbons. Our results highlight a promising new class of low‐cost, abundant electrocatalysts for synthetic fuel production from CO2. 相似文献
76.
Fused Corrole Dimers Interconvert between Nonaromatic and Aromatic States through Two‐Electron Redox Reactions 下载免费PDF全文
Shota Ooi Dr. Takayuki Tanaka Kyu Hyung Park Sangsu Lee Prof. Dr. Dongho Kim Prof. Dr. Atsuhiro Osuka 《Angewandte Chemie (International ed. in English)》2015,54(10):3107-3111
A singly linked corrole dimer was synthesized by condensation of a dipyrromethane‐1‐carbinol with 1,1,2,2‐tetrapyrroethane. Oxidation of the dimer gave doubly linked corrole dimers 9 and 10 as the first examples of fused corrole dimers involving a meso–meso linkage. Dimers 9 and 10 exhibit characteristic 1H NMR spectra, absorption spectra, excited‐state dynamics, and two‐photon absorption (TPA) values, which indicate the nonaromatic nature of 9 and the aromatic nature of 10 . Interestingly, 9 is fairly stable despite its unusual 2H‐corrole structure, which has been ascribed to the presence of two direct connections between the individual corrole units. 相似文献
77.
Back Cover: Cofactor‐Free Light‐Driven Whole‐Cell Cytochrome P450 Catalysis (Angew. Chem. Int. Ed. 3/2015) 下载免费PDF全文
78.
Jun‐Seok Lee Jae Wook Lee Namyoung Kang Hyung‐Ho Ha Young‐Tae Chang 《Chemical record (New York, N.Y.)》2015,15(2):495-510
Synthetic molecules that modulate and probe biological events are critical tools in chemical biology. Utilizing combinatorial and diversity‐oriented synthetic strategies, access to large numbers of small molecules is becoming more and more feasible, and research groups in this field can take advantage of the power of chemical diversity. Since the majority of early studies were focused on the discovery of compounds that perturb protein functions, diversity‐based approaches are often considered as therapeutic lead discovery tactics. However, the diversity‐oriented approach can also be applied to advance distinct aims, such as target protein identification, or the development of imaging probes and sensors. This review provides a personal perspective of the chemical‐diversity‐based approach and how this principle can be adapted to various chemical biology studies. 相似文献
79.
Rücktitelbild: Cofactor‐Free Light‐Driven Whole‐Cell Cytochrome P450 Catalysis (Angew. Chem. 3/2015)
80.