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921.
922.
In the recrystallization of a diastereomeric mixture of amides (RSa,S)-1 formed from racemic 1,1′-binaphthalene-2,2′-dicarboxylic acid and (S)-1-phenylethylamine, either of the diastereomers crystallizes out as a diastereomerically pure form, depending on the solvent employed; sterically undemanding solvents, acetone, dichloromethane, and acetonitrile, afford crystals formulated as (Sa,S)-1·solvent with an exception of ethanol, which affords (Ra,S)-1·EtOH, while sterically bulkier solvents afford (Ra,S)-1 including no solvent. The stereoselectivity can be rationalized by the crystal structures. A dielectrically controlled resolution (DCR) can also be carried out by using mixed solvents, which contain, for example, 25 vol % of acetone and varying ratios of hexane and 1-propanol in total 75 vol %; (Sa,S)-1·acetone is deposited as crystals from the solvents with a dielectric constant (ε) range 8.9 ? ε ? 10.2, while (Ra,S)-1 is deposited from the solvents with 14.8 ? ε ? 20.3. 相似文献
923.
Yoshihiro Asayama Yuki Kawasaki Seog-Jin Kim Atsuhiro Nakamoto Kenta Ozeki 《Discrete Mathematics》2018,341(11):2988-2994
An -dynamic -coloring of a graph is a proper -coloring such that any vertex has at least distinct colors in . The -dynamic chromatic number of a graph is the least such that there exists an -dynamic -coloring of .Loeb et al. (2018) showed that if is a planar graph, then , and there is a planar graph with . Thus, finding an optimal upper bound on for a planar graph is a natural interesting problem. In this paper, we show that if is a planar triangulation. The upper bound is sharp. 相似文献
924.
柱后缓冲电导法采用柱后调节pH值,电导检测器检测的方法检测有机酸,它避免了经常使用的紫外法选择性差,直接电导法灵敏度低的缺点,是可以实现有机酸准确定量的一种新型分析方法.本文比较了这三种方法的分析结果. 相似文献
925.
采用自动前处理LC/MS进行血浆中药物的快速分析 总被引:3,自引:0,他引:3
药物研究的发展对高通量的样品处理分析提出了越来越高的要求,减少样品制备时间和分析时间是解决问题的关键。我们新近发展了一种具有在线稀释旁路和新的样品预处理柱的Shim-Pack MAYI-ODS自动柱切换HPLC和LC/MS系统,该系统无需样品前处理,可直接进样进行血浆、血清中的药物分析。本文利用自动样品前处理LC/MS系统,用ODS整体柱实现了血浆中药物的快速分析。包括样品预处理,整个分析仅需1.2min完成。 相似文献
926.
Motoyasu Kobayashi Hiroki Yamaguchi Yuki Terayama Zhe Wang Kazuhiko Ishihara Masahiro Hino Atsushi Takahara 《Macromolecular Symposia》2009,279(1):79-87
Zwitterionic and cationic polyelectrolyte brushes were prepared by surface-initiated atom transfer radical polymerization of 2-methacryloyloxy- ethyl phosphorylcholine (MPC) and 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA), respectively. The poly(DMAEMA) brush was treated with methyl iodide to form poly[2-(methacryloyloxy) ethyltrimethylammonium iodide] [poly(METAI)]. The effects of ionic strength on brush structure and surface properties of densely grafted polyelectrolyte brushes were analyzed by contact angle measurements, neutron reflectivity (NR) and macroscopic friction tests. Both polyelectrolyte brushes exhibited hydrophilic properties. The contact angle of the poly(MPC) brush surface against water was ca. 0° in air and the contact angle of the air bubble in water was ca. 170°. The air bubble in water hardly attached to the poly(MPC) brush surface, indicating super hydrophilic characteristics. NR measurements of poly(MPC) and poly(METAI) brushes showed that the grafted polymer chains were extended from the substrate surface in a good solvent such as water. Interestingly, NR study did not reveal the shrinkage of the brush chain in salt solution. The polyelectrolyte brushes immersed in both water and NaCl solution at various concentrations showed a low friction coefficient and low adhesion force. 相似文献
927.
928.
Hidetaro Yasumitsu Yasuhiro Ozeki Sarkar M. A. Kawsar Yuki Fujii Masayuki Sakagami Yuhsi Matuo Tosifusa Toda Hiroshi Katsuno 《Electrophoresis》2010,31(12):1913-1917
SDS‐PAGE and CBB staining are two of the most popular methods used for protein analysis. Although many reports that describe such staining methods have been published, these conventional protocols require several hours or days for staining and de‐staining. In this study we describe a recently developed, fast and sensitive CBB staining method that utilizes the staining solution of RAMA that consists of the low‐cost reagents: CBB R250, acetic acid, methanol and ammonium sulfate, and the destaining solution of water. Our method dose dependently detects 12 nanograms protein within 60 min and with a wide protein spectrum. Although the features of the dose‐dependent relationship depend upon protein amounts and protein types, for most of the protein samples tested, a linear relationship was observed in the region from 12 to 330 ng. Moreover, through further washing, the detection sensitivity of protein is enhanced and reaches a maximum at 1.4 ng and then gradually decreases in the de‐staining process. It has been shown recently through MS analyses that the sensitive colloidal CBB staining methods frequently result in artifactual methylations due to the strong acid and long contact during staining and the destaining processes. Such artifacts were reported to be reduced by the replacement of strong inorganic acid with acetic acid and because RAMA utilizes acetic acid and is in contact with the proteins for a short time during staining and de‐staining, it is expected that in vitro artifacts will be reduced. Finally, MS analyses of RAMA‐stained protein bands were revealed not to have been methylated. 相似文献
929.
930.
Qifeng Zheng Shota Miura Kasumi Miyazaki Seongjae Ko Eriko Watanabe Masaki Okoshi Chien‐Pin Chou Yoshifumi Nishimura Hiromi Nakai Takeshi Kamiya Tsunetoshi Honda Jun Akikusa Yuki Yamada Atsuo Yamada 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14340-14345
Aqueous Na‐ or K‐ion batteries could virtually eliminate the safety and cost concerns raised from Li‐ion batteries, but their widespread applications have generally suffered from narrow electrochemical potential window (ca. 1.23 V) of aqueous electrolytes that leads to low energy density. Herein, by exploring optimized eutectic systems of Na and K salts with asymmetric imide anions, we discovered, for the first time, room‐temperature hydrate melts for Na and K systems, which are the second and third alkali metal hydrate melts reported since the first discovery of Li hydrate melt by our group in 2016. The newly discovered Na‐ and K‐ hydrate melts could significantly extend the potential window up to 2.7 and 2.5 V (at Pt electrode), respectively, owing to the merit that almost all water molecules participate in the Na+ or K+ hydration shells. As a proof‐of‐concept, a prototype Na3V2(PO4)2F3|NaTi2(PO4)3 aqueous Na‐ion full‐cell with the Na‐hydrate‐melt electrolyte delivers an average discharge voltage of 1.75 V, that is among the highest value ever reported for all aqueous Na‐ion batteries. 相似文献