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151.
We prove a numerical characterization of ?n for varieties with at worst isolated local complete intersection quotient singularities. In dimension 3, we prove such a numerical characterization of ?3 for normal ?-Gorenstein projective varieties. 相似文献
152.
Wei Shyang Tan Ting‐Yin Lee Sheng‐Fang Tseng Ying‐Feng Hsu Masanori Ebina Tetsuya Taketsugu Shing‐Jong Huang Jye‐Shane Yang 《中国化学会会志》2019,66(9):1141-1156
Despite the long history of polyaniline chemistry, backbone‐substituted polyanilines are limited. Here, we report the synthesis of pentiptycene‐incorporated polyanilines through acidic aniline oxidative polymerization with three pentiptycene derivatives, TA, DA, and TP, as nucleate additives. The reactivity of TA > DA ? TP, as evidenced by structural and property analysis of the corresponding polyaniline products, demonstrates a radical coupling mechanism and the formation of Dewar π‐complex intermediates for the chain propagation. In addition, the iptycene substituent effect on enhancing the electrochemical stability and charge storage capability of polyaniline are discussed with a clip model, namely, the threading of neighboring polyaniline chains through the U‐ and V‐shaped cavities of pentiptycene restricts lateral motions of the polymer chains and promotes interchain conductivity. Density function theory (DFT) calculations suggest a larger clipping effect for the U versus V cavities. Both the conclusion of a terminal planar p‐phenylenediamine (ppda) group being the key component of an effective nucleate and the concept of interchain clipping for enhanced electrochemical performance should facilitate the design and synthesis of novel polyanilines for electronic applications. 相似文献
153.
Structural Chemistry - Alternariol and alternariol monomethyl ether are mycotoxins occasionally found in food and beverages that have been contaminated by certain fungi of the Alternaria genus.... 相似文献
154.
We study the combined effects of dynamic gain saturation and two-photon absorption on the amplification of short pulses in semiconductor optical amplifiers and show that two-photon absorption can saturate the amplifier gain and limit the output pulse energies even for amplifiers with large gain saturation energies. We discuss the upper limits for the pulse energies obtainable from semiconductor optical amplifiers in the presence of two-photon absorption and show that for single transverse mode waveguide amplifiers these upper limits can range from values as small as a few picojoules to several hundred picojoules for pulse widths in the 0.5 ps to 20 ps range, respectively. 相似文献
155.
Low Density Self-Assembled InAs/GaAs Quantum Dots Grown by Metal Organic Chemical Vapour Deposition
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The self-assembled InAs quantum dots (QDs) on GaAs substrates with low density (5×10^8 cm^-2) are achieved using relatively higher growth temperature and low InAs coverage by low-pressure metal-organic chemical vapour deposition. The macro-PL spectra exhibit three emission peaks at 1361, 1280 and 1204nm, corresponding to the ground level (GS), the first excited state (ES1) and the second excited state (ES2) of the QDs, respectively, which are obtained when the GaAs capping layer is grown using triethylgallium and tertiallybutylarsine. As a result of micro-PL, only a few peaks from individual dots have been observed. The exciton-biexciton behaviour was clearly observed at low temperature. 相似文献
156.
Long range correlation analysis and charge conductivity investigation are applied to sequences in 16 chromosomes in the Saccharomyces cerevisiae genome. DNA sequence data are analyzed via Hurst’s analysis and Detrended Fluctuation Analysis (DFA) analysis. Super diffusive nature of mapping sequences are evident with the measured Hurst exponent H to be around the value of 0.60 for all sequences in the 16 chromosomes. The DFA result is consistent with the result from the Hurst analysis. Tight binding models are applied for the investigation of charge conduction through DNA sequences. The overall averaged transmission coefficients, 〈TN〉av, calculated from sixteen chromosomes are shown to be significantly different from values calculated from random as well as periodic sequences. Sequences from the S. cerevisiae genome promise better charge conduction ability than random sequences. Finally, delocalized electronic wave function patterns are also shown through calculations using the tight binging model. Slightly delocalized electronic wavefunctions are seen on sequences in sixteen chromosomes, as compared with those obtained from random sequences on the same eigenenergies. 相似文献
157.
Cheng-Cheng Tsai Zhi-Yao Tsai Ming-Yu Tseng Wei-Ping Hu 《International journal of quantum chemistry》2020,120(14):e26238
We have developed a new database of structures and bond energies of 59 noble-gas-containing molecules. The structures were calculated by CCSD(T)/aug-cc-pVTZ methods and the bond energies were obtained using the CCSD(T)/complete basis set method. Many wavefunction-based and density functional theory methods have been benchmarked against the 59 accurate bond energies. Our results show that the MPW1B95, B2GP-PLYP, and DSD-BLYP functionals with the aug-cc-pVTZ basis set excel in predicting the bond energies of noble-gas molecules with mean unsigned errors (MUEs) of 2.0 to 2.1 kcal/mol. When combinations of Dunning's basis sets are used, the MPW1B95, B2GP-PLYP, DSD-BLYP, and BMK functionals give significantly lower MUEs of 1.6 to 1.9 kcal/mol. Doubly hybrid methods using B2GP-PLYP and DSD-BLYP functionals and MP2 calculation also provide satisfactory accuracy with MUEs of 1.4 to 1.5 kcal/mol. If the Ng bond energies and the total atomization energies of a group of 109 main-group molecules are considered at the same time, the MPW1B95/aug-cc-pVTZ single-level method (MUE = 2.7 kcal/mol) and the B2GP-PLYP and DSD-PLYP functionals with combinations of basis sets or using the doubly hybrid method (MUEs = 1.9-2.2 kcal/mol) give the overall best result. 相似文献
158.
Journal of Nanoparticle Research - Ni-doped (CeO2?δ )–YSZ (5 mol% Ni oxide, 10 mol% ceria) mesoarchitectures (MA) with nanocrystalline framework have been... 相似文献
159.
Redox Communication within Multinuclear Iron–Sulfur Complexes Related to Electronic Interplay in the Active Site of [FeFe]Hydrogenase
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Kai‐Ti Chu Dr. Yu‐Chiao Liu Yi‐Lan Huang Dr. Gene‐Hsiang Lee Dr. Mei‐Chun Tseng Prof. Ming‐Hsi Chiang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6852-6861
The one‐electron oxidations of a Fe2 complex lead to the formation of a persistent metal‐stabilized thiyl radical Fe2 species, mixed‐valent Fe4, and Fe8 complexes. The unpaired spin in the Fe2 radical species delocalizes over the Fe2 and the aromatic dithiolate, mostly on the terminal sulfur. The subsequent dimerization of the singly oxidized Fe2 to the Fe4 retains the partial thiyl radical character. For an analogue with less steric hindrance, the π–π stacking interaction between the dithiolato aromatic rings induces generation of the Fe8, in which process electronic structures of the species are modulated through reducing the thiyl radical to the thiolate. Electronic reorganization repeats when the Fe8 is converted to Fe4. Electronic interplay in the complexes decreases the energy gap of frontier MOs and buffers electronic impacts upon redox events. Easier accessible redox potentials and increased stability of the species are facilitated. The results demonstrate that electronic versatility of the benzenedithiolate exerts pronounced influences on electronic and coordination structure of the metal complexes. 相似文献
160.