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991.
992.
993.
Measuring the thermal conductivity of a single carbon nanotube 总被引:1,自引:0,他引:1
Fujii M Zhang X Xie H Ago H Takahashi K Ikuta T Abe H Shimizu T 《Physical review letters》2005,95(6):065502
Although the thermal properties of millimeter-sized carbon nanotube mats and packed carbon nanofibers have been readily measured, measurements for a single nanotube are extremely difficult. Here, we report a novel method that can reliably measure the thermal conductivity of a single carbon nanotube using a suspended sample-attached T-type nanosensor. Our experimental results show that the thermal conductivity of a carbon nanotube at room temperature increases as its diameter decreases, and exceeds 2000 W/mK for a diameter of 9.8 nm. The temperature dependence of the thermal conductivity for a carbon nanotube with a diameter of 16.1 nm appears to have an asymptote near 320 K. The present method is, in principle, applicable to any kind of a single nanofiber, nanowire, and even single-walled carbon nanotube. 相似文献
994.
We report on a pressure- (P-)induced evolution of superconductivity and spin correlations in CeIrIn(5) via the (115)In nuclear-spin-lattice-relaxation rate measurements. We find that applying pressure suppresses dramatically the antiferromagnetic fluctuations that are strong at ambient pressure. At P = 2.1 GPa, T(c) increases to T(c) = 0.8 K, which is twice T(c) (P = 0 GPa), in the background of Fermi-liquid state. This is in sharp contrast to the previous case in which a negative, chemical pressure (replacing Ir with Rh) enhances magnetic interaction and increases T(c). Our results suggest that multiple mechanisms work to produce superconductivity in the same compound CeIrIn(5). 相似文献
995.
Reactions of a quadridentate ligand [N-(2-hydroxy-5-nitrobenzyl)iminodiethanol] with iron and manganese chloride in methanol yielded an antiferromagnetic FeIII6 ring and a single-molecule magnet MnII3MnIII4 wheel, respectively. 相似文献
996.
997.
Dr. Yoshiyuki Manabe Hiroki Shomura Naoya Minamoto Dr. Masahiro Nagasaki Yohei Takakura Prof. Katsunori Tanaka Prof. Alba Silipo Prof. Antonio Molinaro Prof. Koichi Fukase 《化学:亚洲杂志》2018,13(12):1544-1551
The chemical synthesis of a bisecting N‐acetylglucosamine (GlcNAc)‐containing N‐glycan was achieved by a convergent synthetic route through [4+2] and [6+2] glycosylations. This synthetic route reduced the number of reaction steps, although the key glycosylations were challenging in terms of yields and selectivities owing to steric hindrance at the glycosylation site and a lack of neighboring group participation. The yields of these glycosylations were enhanced by stabilizing the oxocarbenium ion intermediate through ether coordination. Glycosyl donor protecting groups were explored in an effort to realize perfect α selectivity by manipulating remote participation. The simultaneous glycosylations of a tetrasaccharide with two disaccharides was investigated to efficiently construct a bisecting GlcNAc‐containing N‐glycan. 相似文献
998.
Which One is Bulkier: The 3,5‐Dimethylphenyl or the 2,6‐Dimethylphenyl Group? Development of Size‐Complementary Molecular and Macromolecular [2]Rotaxanes
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We developed novel size‐complementary molecular and macromolecular rotaxanes using a 2,6‐dimethylphenyl terminal group as the axle‐end‐cap group in dibenzo‐24‐crown‐8‐ether (DB24C8)‐based rotaxanes, where the 2,6‐dimethylphenyl group was found to be less bulky than the 3,5‐dimethylphenyl group. A series of molecular and macromolecular [2]rotaxanes that bear a 2,6‐dimethylphenyl group as the axle‐end‐cap were synthesized using unsubstituted and fluorine‐substituted DB24C8. Base‐induced decomposition into their constituent components confirmed the occurrence of deslipping, which supports the size‐complementarity of these rotaxanes. The deslipping rate was independent of the axle length but dependent on the DB24C8 substituents. A kinetic study indicated the rate‐determining step was that in which the wheel is getting over the end‐cap group, and deslipping proceeded via a hopping‐over mechanism. Finally, the present deslipping behavior was applied to a stimulus‐degradable polymer as an example for the versatile utility of this concept in the context of stimulus‐responsive materials. 相似文献
999.
Undoped Layered Perovskite Oxynitride Li2LaTa2O6N for Photocatalytic CO2 Reduction with Visible Light
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![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Takayoshi Oshima Tom Ichibha Ken Sinkou Qin Kanemichi Muraoka Dr. Junie Jhon M. Vequizo Keisuke Hibino Ryo Kuriki Dr. Shunsuke Yamashita Prof. Dr. Kenta Hongo Dr. Tomoki Uchiyama Prof. Dr. Kotaro Fujii Dr. Daling Lu Prof. Dr. Ryo Maezono Prof. Dr. Akira Yamakata Prof. Dr. Hideki Kato Dr. Koji Kimoto Prof. Dr. Masatomo Yashima Prof. Dr. Yoshiharu Uchimoto Prof. Dr. Masato Kakihana Prof. Dr. Osamu Ishitani Prof. Dr. Hiroshi Kageyama Prof. Dr. Kazuhiko Maeda 《Angewandte Chemie (International ed. in English)》2018,57(27):8154-8158
Oxynitrides are promising visible‐light‐responsive photocatalysts, but their structures are almost confined with three‐dimensional (3D) structures such as perovskites. A phase‐pure Li2LaTa2O6N with a layered perovskite structure was successfully prepared by thermal ammonolysis of a lithium‐rich oxide precursor. Li2LaTa2O6N exhibited high crystallinity and visible‐light absorption up to 500 nm. As opposed to well‐known 3D oxynitride perovskites, Li2LaTa2O6N supported by a binuclear RuII complex was capable of stably and selectively converting CO2 into formate under visible light (λ>400 nm). Transient absorption spectroscopy indicated that, as compared to 3D oxynitrides, Li2LaTa2O6N possesses a lower density of mid‐gap states that work as recombination centers of photogenerated electron/hole pairs, but a higher density of reactive electrons, which is responsible for the higher photocatalytic performance of this layered oxynitride. 相似文献
1000.
Masayoshi Miyahara Hiroki Shiozaki Hideyuki Tukada Yuichi Ishikawa Masato Oikawa 《Tetrahedron letters》2018,59(48):4259-4262
Herein, we disclose an efficient combination of NPEC and Ns protecting groups in the synthesis of polyamine, by showing the orthogonal reactivity using N-NPEC-N-Ns alkylamines prepared from NPEC-NHNs. Selective photodeprotection of NPEC group in 12-mer polyamine and the complex conjugate has been further demonstrated toward the synthesis of novel polyamine natural product protoaculeine B. 相似文献