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1.
Mathematical Programming - Many practical integer programming problems involve variables with one or two-sided bounds. Dunkel and Schulz (A refined Gomory–Chvátal closure for polytopes... 相似文献
2.
Mika Sakai Masayoshi Mori Dr. Masato Hirai Dr. Naoki Ando Prof. Dr. Shigehiro Yamaguchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(38):e202200728
Two kinds of planarized phenyldithienylboranes, which contain (CH3)2C- or CH2-bridging moieties, were synthesized. The difference of the bridging moieties affects their packing structures and photophysical properties. In particular, the (CH3)2C-bridged derivative exhibits a large Stokes shift, unusual for such planarized compounds, that results from a large structural relaxation in the excited state. A series of π-extended derivatives was synthesized, among which a p-(diphenylamino)phenyl-substituted derivative shows large solvatochromism in the fluorescence spectra, while maintaining high quantum yields even in polar solvents. The Lewis acidity of the phenyldithienylborane derivatives was also assessed by titration with pyridine. The Lewis acidity of the boron center is affected not only by the difference in the steric bulk of the bridging moieties, but also by the electronic effect of the substituents introduced at remote positions relative to the boron atom. These results demonstrate the characteristic features of planarized phenyldithienylboranes as building blocks for boron-based π-electron materials. 相似文献
3.
Nobuyuki Otozawa Rio Hamajima Masataka Yoshioka Raito Kato Arisa Tanaka Hiroto Fukuma Toshiki Terao Kei Manabe Syuji Fujii Yoshinobu Nakamura Atsushi Takahara Tomoyasu Hirai 《Journal of polymer science. Part A, Polymer chemistry》2020,58(14):1960-1964
This study investigates the effect of ionic liquids (ILs) on the anionic polymerization of methyl methacrylate (MMA). Polymethyl methacrylate (PMMA), an isotactic polymer, is prepared by anionic polymerization at a high reaction temperature with an IL that acts as both solvent and additive. The most plausible reaction mechanism is determined using 1H NMR and Fourier-transform infrared spectroscopy. The electrostatic interaction between MMA and the IL increases the apparent steric hindrance in MMA, resulting in the isotactic PMMA. 相似文献
4.
Takahiro Moriyama Daiki Mizukami Dr. Makoto Yoritate Dr. Kazuteru Usui Dr. Daisuke Takahashi Dr. Eisuke Ota Prof. Dr. Mikiko Sodeoka Prof. Dr. Tadashi Ueda Prof. Dr. Satoru Karasawa Prof. Dr. Go Hirai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(11):e202103925
Minimalist photo-reactive probes, which consist of a photo-reactive group and a tag for detection of target proteins, are useful tools in chemical biology. Although several diazirine-based and aryl azide-based minimalist probes are available, no keto-based minimalist probe has yet been reported. Here we describe minimalist probes based on a 2-thienyl-substituted α-ketoamide bearing an alkyne group on the thiophene ring. The 3-alkyne probe showed the highest photo-affinity labeling efficiency. 相似文献
5.
Hiroki Hirai Kiichi Nakajima Soichiro Nakatsuka Kazushi Shiren Jingping Ni Shintaro Nomura Toshiaki Ikuta Takuji Hatakeyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(46):13785-13789
The development of a one‐step borylation of 1,3‐diaryloxybenzenes, yielding novel boron‐containing polycyclic aromatic compounds, is reported. The resulting boron‐containing compounds possess high singlet‐triplet excitation energies as a result of localized frontier molecular orbitals induced by boron and oxygen. Using these compounds as a host material, we successfully prepared phosphorescent organic light‐emitting diodes exhibiting high efficiency and adequate lifetimes. Moreover, using the present one‐step borylation, we succeeded in the synthesis of an efficient, thermally activated delayed fluorescence emitter and boron‐fused benzo[6]helicene. 相似文献
6.
Hidefumi Hirai 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):1491-1500
Terephthalic acid was synthesized by the carboxylation of benzoic acid with carbon tetrachloride in aqueous sodium hydroxide solution in the presence of cyclodextrin (CyD) and copper powder as catalyst. By the use of β-CyD at the initial molar ratio to benzoic acid of 0.5, the carboxylation at 60 °C for 7 hours produced terephthalic acid in 75 mol% yield with 87% selectivity. The selective synthesis of 4,4'-biphenyldicarboxylic acid in 70 mol% yield was achieved by the carboxylation of 4-biphenylcarboxylic acid with carbon tetrachloride in the presence of β-Cyd under similar conditions. The carboxylation of 2-naphthalene carboxylic acid with carbon tetrachloride using β-Cyd under similar conditions produced 2,6-naphthalenedicarboxylic acid in 67 mol% yield with 84% selectivity. When α-CyD and γ-CyD were used in place of β-Cyd, both the yields and the selectivities of the dicarboxylic acids were markedly small. In the absence of CyD, carboxylation did not proceed. Inclusion complex formations between β-Cyd and aromatic monocarboxylic acids were indicated by the 1H chemical shifts of the β-Cyd. The reaction mechanism was discussed on the basis of inclusion complex formation. 相似文献
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9.
A great number of studies of polyelectrolyte complexes have been carried out by various investigators; most of them concentrated on the reaction between oppositely charged polyelectrolytes [1-3]. The structure and properties of the resultant complexes have been investigated to a lesser extent, and the understanding of this new class of polymer materials is still insufficient. Thus, we have been investigating the sorption of water vapor by the complexes and the morphological changes caused by this sorption [4,5]. 相似文献
10.
Mostafa Abdelrahman Sho Hirata Takuya Mukae Tomohiro Yamada Yuji Sawada Magdi El-Syaed Yutaka Yamada Muneo Sato Masami Yokota Hirai Masayoshi Shigyo 《Molecules (Basel, Switzerland)》2021,26(5)
Garlic (Allium sativum) is the second most important Allium crop that has been used as a vegetable and condiment from ancient times due to its characteristic flavor and taste. Although garlic is a sterile plant that reproduces vegetatively through cloves, garlic shows high biodiversity, as well as phenotypic plasticity and environmental adaptation capacity. To determine the possible mechanism underlying this phenomenon and to provide new genetic materials for the development of a novel garlic cultivar with useful agronomic traits, the metabolic profiles in the leaf tissue of 30 garlic accessions collected from different geographical regions, with a special focus on the Asian region, were investigated using LC/MS. In addition, the total saponin and fructan contents in the roots and cloves of the investigated garlic accessions were also evaluated. Total saponin and fructan contents did not separate the garlic accessions based on their geographical origin, implying that saponin and fructan contents were clone-specific and agroclimatic changes have affected the quantitative and qualitative levels of saponins in garlic over a long history of cultivation. Principal component analysis (PCA) and dendrogram clustering of the LC/MS-based metabolite profiling showed two major clusters. Specifically, many Japanese and Central Asia accessions were grouped in cluster I and showed high accumulations of flavonol glucosides, alliin, and methiin. On the other hand, garlic accessions grouped in cluster II exhibited a high accumulation of anthocyanin glucosides and amino acids. Although most of the accessions were not separated based on country of origin, the Central Asia accessions were clustered in one group, implying that these accessions exhibited distinct metabolic profiles. The present study provides useful information that can be used for germplasm selection and the development of new garlic varieties with beneficial biotic and abiotic stress-adaptive traits. 相似文献