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排序方式: 共有661条查询结果,搜索用时 31 毫秒
1.
Feng Cheng Shuqi Wu Wenwei Zheng Shengqun Su Takumi Nakanishi Wenhuang Xu Pritam Sadhukhan Hibiki Sejima Shimon Ikenaga Kaoru Yamamoto Kaige Gao Shinji Kanegawa Prof. Osamu Sato 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(59):e202202161
The crystallization of a complex having electron transfer properties in a polar space group can induce the polarization switching of a crystal in a specific direction, which is attractive for the development of sensors, memory devices, and capacitors. Unfortunately, the probability of crystallization in a polar space group is usually low. Noticing that enantiopure compounds crystallize in Sohncke space groups, this paper reports a strategy for the molecular design of non-ferroelectric polarization switching crystals based on the use of intramolecular electron transfer and chirality. In addition, this paper describes the synthesis of a mononuclear valence tautomeric (VT) cobalt complex bearing an enantiopure ligand. The introduction of enantiomer enables the crystallization of the complex in the polar space group (P21). The polarization of the crystals along the b-axis direction is not canceled out and the VT transition is accompanied by a change in the macroscopic polarization of the polar crystal. Polarization switching via electron transfer is realized at around room temperature. 相似文献
2.
Dr. Shiguo Zhang Prof. Seiji Tsuzuki Dr. Kazuhide Ueno Prof. Kaoru Dokko Prof. Masayoshi Watanabe 《Angewandte Chemie (International ed. in English)》2015,54(4):1302-1306
Nitrogen‐doped carbon materials (NDCs) play an important role in various fields. A great deal of effort has been devoted to obtaining carbon materials with a high nitrogen content; however, much is still unknown about the structure of the nitrogen‐doped materials and the maximum nitrogen content possible for such compounds. Here, we demonstrate an interesting relationship between the N/C molar ratio and the N content of NDCs. The upper limit for the nitrogen content of NDCs that might be achieved was estimated and found to strongly depend on the carbonization temperature (14.32 wt % at 1000 °C and 21.66 wt % at 900 °C), irrespective of the precursor or preparation conditions. Simulations suggest that, especially in the carbon architectures obtained at high temperatures, nitrogen atoms are always located on separate hexagon moieties in a graphitic configuration, thereby yielding a critical N/C molar ratio very close to the value estimated from the experimental results. 相似文献
3.
A linear network code is called k-secure if it is secure even if an adversary eavesdrops at most k edges. In this paper, we show an efficient deterministic construction algorithm of a linear transformation T that transforms an (insecure) linear network code to a k-secure one for any k, and extend this algorithm to strong k-security for any k . Our algorithms run in polynomial time if k is a constant, and these time complexities are explicitly presented. We also present a concrete size of \(|\mathsf{F}|\) for strong k-security, where \(\mathsf{F}\) is the underling finite field. 相似文献
4.
We construct identity-based encryption and inner product encryption schemes under the decision linear assumption. Their private user keys are leakage-resilient in several scenarios. In particular, In addition, we prove that our IBE schemes are anonymous under the DLIN assumption, so that ciphertexts leaks no information on the corresponding identities. Similarly, attributes in IPE are proved computationally hidden in the corresponding ciphertexts.
相似文献
- In the bounded memory leakage model (Akavia et al., TCC, vol. 5444, pp. 474–495, 2009), our basic schemes reach the maximum-possible leakage rate \(1-o(1)\).
- In the continual memory leakage model (Brakerski et al., Overcoming the hole in the bucket: public-key cryptography resilient to continual memory leakage, 2010; Dodis et al., Cryptography against continuous memory attacks, 2010), variants of the above schemes enjoy leakage rate at least \(\frac{1}{2} -o(1)\). Among the results, we improve upon the work of Brakerski et al. by presenting adaptively secure IBE schemes.
5.
Keisuke Akita Youhi Morii Hisashi Nakamura Takuya Tezuka Kaoru Maruta 《Proceedings of the Combustion Institute》2021,38(2):2247-2255
Two-dimensional axisymmetric numerical simulation reproduced flames with repetitive extinction and ignition (FREI) in a micro flow reactor with a controlled temperature profile with a stoichiometric n-heptane/air mixture, which have been observed in the experiment. The ignition of hot flame occurred from consumption reactions of CO that was remained in the previous cycle of FREI. Between extinction and ignition locations of hot flames, several other heat release rate peaks related to cool and blue flames were observed for the first time. After the extinction of the hot flame, cool flame by the low-temperature oxidation of n-heptane appeared first and was stabilized in a low wall temperature region. In the downstream of the stable cool flame, a blue flame by the consumption reactions of cool flame products of CH2O and H2O2 appeared. After that, the hot flame ignition occurred from the remaining CO in the downstream of the blue flame. Then after the next hot flame ignition, the blue flame was swept away by the propagating hot flame. Soon before the hot flame merged with the stable cool flame, the hot flame propagation was intensified by the cool flame. After the hot flame merged with the stable cool flame, the hot flame reacted with the incoming fresh mixture of n-C7H16 and O2. 相似文献
6.
Dr. Yasunori Toda Takayuki Yoshida Kaoru Arisue Prof. Dr. Kazuaki Fukushima Dr. Hiroyoshi Esaki Ayaka Kikuchi Prof. Dr. Hiroyuki Suga 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(41):10578-10582
Chiral Lewis acid-catalyzed asymmetric alcohol addition reactions to cyclic carbonyl ylides generated from N-(α-diazocarbonyl)-2-oxazolidinones featuring a dual catalytic system are reported. Construction of a chiral quaternary heteroatom-substituted carbon center was accomplished in which the unique heterobicycles were obtained in good yields with high stereoselection. The alcohol adducts were successfully converted to optically active oxazolidine-2,4-diones by hydrolysis. Mechanistic studies by DFT calculations revealed that alcohols could be activated by Lewis acids, enabling enantioselective protonation of the carbonyl ylides. 相似文献
7.
8.
Masahiro Ishino Kaoru Kinoshita Kunio Takahashi Takashi Sugita Motoo Shiro Kimiko Hasegawa Kiyotaka Koyama 《Tetrahedron》2012,68(41):8572-8576
Three novel diterpenes, phomactins K–M (1–3), were isolated from the cultures of an unidentified marine-derived fungus. The structures of 1–3 were elucidated from spectroscopic data (NMR, MS, IR), and the absolute configurations of 1, 2, and the relative configuration of 3 were determined by X-ray diffraction analysis. 相似文献
9.
Tsung-Sheng Chang Kaoru Tone Chen-Hui Wu 《The Journal of the Operational Research Society》2015,66(1):16-32
It has been well recognized that to thoroughly evaluate a firm’s performance, the evaluator must assess not only its past and present records but also future potential. However, to the best of our knowledge, there are no data envelopment analysis (DEA)-type models proposed in the literature that simultaneously take past, present and, especially, future performance indicators into account. Hence, this research aims at developing a new type of DEA model referred to as Intertemporal DEA models that can be used to fully measure a firm’s efficiency by explicitly considering its key inputs and outputs involving the past-present-future time span. In this research, the proposed Intertemporal DEA models are applied to the performance evaluation of high-tech Integrated Circuit design companies in Taiwan to demonstrate their advantages over other DEA models that ignore intertemporal efficiency. 相似文献
10.
Journal of Solid State Electrochemistry - The stress variations during polarization of iron thin film electrode in pH 8.4 borate buffer solution have been measured by a cantilever bending... 相似文献