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991.
Raghavendhar R. Kotha Ravikiran Yerabolu Duanchen Ding Lucas Szalwinski Xin Ma Ashley Wittrig John Kong John J. Nash Hilkka I. Kenttämaa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(17):4472-4477
The reactivity of a carbon-centered σ,σ,σ,σ-type singlet-ground-state tetraradical containing two meta-benzyne moieties was examined in the gas phase. Surprisingly, the tetraradical showed higher reactivity than its individual meta-benzyne counterparts. The reactivity of meta-benzynes is controlled by their (calculated) distortion energy ΔE2.3, singlet–triplet spitting ΔES–T, and electron affinity (EA2.3) of the meta-benzyne moiety at the transition state geometry for hydrogen-atom abstraction reactions. The addition of a second meta-benzyne moiety to a meta-benzyne does not significantly change EA2.3. However, ΔE2.3 is substantially decreased for both meta-benzyne moieties in the tetraradical, and this explains their higher reactivities. The decrease in ΔE2.3 for each meta-benzyne moiety in the tetraradical is rationalized by stabilizing spin–spin coupling between one radical site in each meta-benzyne moiety. Therefore, spin–spin coupling between the meta-benzyne moieties in this tetraradical increases its reactivity, whereas spin–spin coupling within each meta-benzyne moiety decreases its reactivity. 相似文献
992.
993.
A trefoil-shaped liquid crystal containing an aromatic hetero-nucleus has been synthesized by the reaction of cyanuric chloride with 3,6-didecanoyl carbazole (DDC). The molecular structure was characterized by 1H NMR and 13C NMR spectroscopy, mass spectroscopy and elemental analysis. The core consists of 1,3,5-triazine directly linked to three carbazole groups. The trefoil-shaped conformation is suggested by molecular modelling. The mesophase was investigated using DSC, X-ray diffraction and polarizing optical microscopy. The X-ray diffraction pattern of a sample cooled slowly from the isotropic state showed sharp peaks in the small angle and wide angle regions implying the existence of a columnar phase with interand intra-columnar ordering. An unusual reticular texture similar to a cholesteric texture was observed. 相似文献
994.
Charles Ng Xiangju Kong Dr. Dongxia Wu Dr. Min Song Dr. Xiaohong Shi Xiaochun Xu Wei‐Han OuYang Rongxian He Prof. Xing‐Zhong Zhao Tom Lee Prof. F. Charles Brunicardi Dr. Mitch André Garcia Prof. Antoni Ribas Prof. Roger S. Lo Prof. Hsian‐Rong Tseng 《Angewandte Chemie (International ed. in English)》2013,52(12):3379-3383
995.
Xin Jia Jun-jun Wei Yuechan Kong Cheng-ming Li Jinlong Liu Liangxian Chen Fangyuan Sun Xinwei Wang 《Surface and interface analysis : SIA》2019,51(7):783-790
The cooling behavior of GaN-on-diamond substrate can be enhanced by reducing the thermal boundary resistance (TBR), which is mainly determined by the nature of interlayer. Although SiN film is considered as the primary candidate of dielectric layer, it is still needed to be optimized. In order to facilitate the understanding of the influence of dielectric layer on the TBR of GaN-on-Diamond substrate, aluminum nitride (AlN), and silicon nitride (SiN) film were compared systematically, both of which are 100 nm. The time-domain thermoreflectance (TDTR) measurements, adhesion evaluation, and microstructural analysis methods were adopted to analyse these two interlayers. The results show the TBR of SiN interlayer is as low as 38.5 ± 2.4 m2K GW−1, comparing with the value of 56.4 ± 5.5 m2K GW−1 for AlN interlayer. The difference of TBR between these two interlayers is elucidated by the diamond nucleation density, and the adhesion between the diamond film and GaN substrate, both of which are affected by the surface charge and chemical groups of the dielectric layer. 相似文献
996.
The light intensity distribution (LID) reflected by a planar corner-cube retroreflector array with the size of centimeter and above (PCCRA) is calculated based on the Collins formula, coordinate transformation matrixes and vector algebra. The expression can be used for the PCCRAs with different parameters and different complex optical systems described by ABCD matrix. The expression indicates that the LID of a PCCRA is much different from a single corner-cube retroreflector (CCR) with equivalent aperture. Computer simulations are applied to explain the expression clearly. The results show that the LID of the PCCRA is more homogeneous than the single CCR with equivalent aperture under circumstances of both normal incident light and oblique incident light. In addition, the expression is proved by comparing the simulation result of the PCCRA only comprising a single CCR and the previous experimental result. 相似文献
997.
Sodium hydrogen sulfite was used to promote condensation of o-phenylenediamine with aromatic aldehydes in dimethylformamide to obtain the corresponding 2-arylbenzimidazoles. The procedure
is simple and convenient, and it implies inexpensive promoter and is characterized by short reaction time and easy purification
of the final products.
Published in Russian in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 6, pp. 872–874.
The text was submitted by the authors in English. 相似文献
998.
Jiangang Li Maosong Fan Xiangming He Rusong Zhao Changyin Jiange Chunrong Wan 《Ionics》2006,12(3):215-218
TiO2-coated LiNi1/3Co1/3Mn1/3O2 materials were prepared by the hydrolyzation of Ti(OBu)4. The impact of TiO2 coating on the structure and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 was investigated using X-ray diffraction, scanning electron microscope, and charge–discharge tests. The results indicated that TiO2 coating did not affect the lattice of LiNi1/3Co1/3Mn1/3O2, but exhibited obvious effects on its discharge capacity and cycling stability. As coated TiO2 increased from 0.0 to 2.0 mol%, the initial capacity of samples decreased slightly, but the cycling stability over 2.5∼4.3 V increased remarkably. The capacity retention reached 99.5% at the 50th cycle at a coating amount of 2.0 mol%. 相似文献
999.
A novel process was proposed to synthesize the pyrolytic polyacrylonitrile (PAN)/SnCl2 composite anode material for Li-ion batteries. The preparation started with the dissolution of PAN and SnCl2 in dimethylformamide (DMF), followed by drying of the solution and pyrolysis of the dried mixture of PAN and SnCl2 at 300 °C, leading to homogenous dispersal of SnCl2 in pyrolytic PAN, which becomes conducting polymer matrix. The composite presented stable cycling capacity of about 490 mAh/g. It is demonstrated that SnCl2, which has been considered to be an inactive electrode material, can become active by the proposed composite technique. This paves the promising way to prepare electrode materials for Li-ion batteries. 相似文献
1000.