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121.
Takeda T Kawai H Fujiwara K Suzuki T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(28):7915-7925
Isolation and low‐temperature X‐ray analyses of intramolecular triarylmethane–triarylmethylium complexes with a naphthalene‐1,8‐diyl‐type skeleton have been achieved. These bridged cations prefer a C? H localized structure both in solution and in the solid state. The bridging hydrogen undergoes a facile intramolecular 1,5‐hydride shift from one carbon to another in solution. The C? H delocalized geometry is suggested to be the transition‐state structure of the degenerate rearrangement. Charge‐transfer interaction from the triarylmethane to the triarylmethylium units is evident in the electronic spectra. This interaction stabilizes the present cations. Low reactivity toward Brønsted acids indicates that these species are not the reaction intermediates in the acid‐assisted long‐bond cleavage of 1,1,2,2‐tetraarylacenaphthene derivatives. 相似文献
122.
Matsumoto H Konosu Y Kimura N Minagawa M Tanioka A 《Journal of colloid and interface science》2007,309(2):272-278
Membrane potential measurement has been widely used for the characterization of ionic membranes such as ion-exchange membranes without solvent permeability. However, there have been few studies on membrane potentials across pressure-driven processes such as reverse osmosis (RO) membranes with solvent permeability. In the present study, the membrane potential across RO membranes in NaCl and MgCl2 under the pressure gradient, DeltaP=0-0.3 MPa, was measured. The experimental results were analyzed by the theoretical model based on the Donnan equilibrium and the extended Nernst-Planck flux equation considering the pressure effect. The theoretical values agreed well with the experimental ones. This indicates that membrane potential is useful for characterizing the effective charge density of the active layer of RO membranes under pressure gradient. 相似文献
123.
Hidetoshi Tomita Fumio Sanda Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2001,39(6):851-859
This article focuses on the structural analysis of polyhydroxyurethane obtained by the reaction of 2,2‐bis[p‐(1,3‐dioxolan‐2‐one‐4‐yl‐methoxy)phenyl]propane with a diamine based on the model reaction. The compounds obtained in the model reaction could be separated into hydroxyurethanes containing primary and secondary alcohol groups by preparative gel permeation chromatography with a recycling technique to determine the structures by 1H NMR, 13C NMR, distortionless enhancement by polarization transfer (DEPT) and C H correlation spectroscopy to obtain hydroxyurethane carrying the primary alcohol structure moiety dominantly. The ratios were independent of the reaction temperature but somewhat dependent on the solvents and amines. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 851–859, 2001 相似文献
124.
Jianhua Fang Kazuhiro Tanaka Hidetoshi Kita Ken‐Ichi Okamoto Yasuo Ito 《Journal of Polymer Science.Polymer Physics》2000,38(9):1123-1132
The positron annihilation lifetime (PAL) of a series of copolyimides and copolyamides with microphase‐separated structures was measured to investigate the effects of different hard‐segment polymers on the PAL properties of soft‐segment domains of poly(dimethyl‐siloxane) (PDMS) and poly(ethylene oxide) (PEO). The lifetime (τ3) and intensity (I3) of the long‐lived component are given as a function of the PDMS or PEO content for a series of copolymers, of which the density roughly obeys the additive rule except for the PDMS‐segmented copolyamides. The PDMS‐segmented copolyimides and copolyamides show much smaller I3 values than those estimated from the additive rule. The lifetime distribution of the long‐lived component for the PDMS‐segmented copolyamides is composed of two components. The longer‐lifetime component is attributed to pure PDMS domains, and the shorter‐lifetime component is attributed to the polyamide domains, intermediate phases, and PDMS domains containing small amounts of short amide blocks. Despite the high PDMS content, the latter component is rather large. Thus, the positronium formation in the PDMS domains of the copolyimides and copolyamides is effectively reduced. This can be explained by the combination of the difference in the electron affinity of the PDMS and polyimide or polyamide segments and the incomplete phase separation. The PEO‐segmented copolyimides show much smaller I3 values than those predicted from the additive rule. This is likely attributable to the effects of the intermediate phases. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1123–1132, 2000 相似文献
125.
Hongyuan Wang Toshinari Ugomori Yong Wang Kazuhiro Tanaka Hidetoshi Kita Ken‐Ichi Okamoto Yasunori Suma 《Journal of Polymer Science.Polymer Physics》2000,38(13):1800-1811
Poly(ethylene oxide imide) segmented copolymer (PEO‐PI) membranes were crosslinked by the chemical reaction between ethylene glycol diglycidyl ether and benzylalcohol groups of diamine moieties in polyimide segments at high temperatures. Sorption and diffusion of penetrants took place in poly(ethylene oxide) segment microdomains. Sorption and desorption behavior of pure vapors such as benzene (Bz), cyclohexane (Cx) and n‐hexane (Hx) was classified as the Fickian diffusion. Sorption isotherms of binary liquid mixtures could be represented by the Flory–Rehner model, but the model overpredicted the sorption amounts of Cx and Hx, leading to small predictions of sorption selectivity αS for Bz/Cx and Bz/Hx systems. UNIFAC‐FV model fairly well predicted the sorption amounts of aromatic hydrocarbons, but significantly overestimated those of nonaromatic ones, leading to too small predictions of αS. Pervaporation (PV) behavior of PEO‐PI membranes was governed by sorption behavior followed by membrane swelling. Diffusion coefficient weakly depended on the minimum cross section of a penetrant. The diffusivity selectivity αD hardly depended on the feed composition and was about 1.4 and 0.75 for Bz/Cx and Bz/Hx, respectively. PV selectivity αPV was larger for Bz/Hx than for Bz/Cx because of larger αS. PEO‐PI membranes displayed high specific permeation flux Ql and reasonably high αPV for aromatic/nonaromatic hydrocarbons; for example, Ql = 60 Kg μm/(m2 h) and αPV = 8 for a feed mixture containing Bz, Tol, Hx, n‐Ot and i‐Ot of 20 wt % at 353 K. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1800–1811, 2000 相似文献
126.
127.
Dr. Fenghua Ding Atsunori Doi Dr. Takafumi Ogawa Dr. Hiroki Ubukata Dr. Tong Zhu Dr. Daichi Kato Dr. Cédric Tassel Dr. Itaru Oikawa Dr. Naoki Inui Dr. Satoru Kuze Tsutomu Yamabayashi Dr. Kotaro Fujii Prof. Masatomo Yashima Prof. Xing Ou Dr. Zhijian Wang Prof. Xiaobo Min Prof. Koji Fujita Prof. Hitoshi Takamura Prof. Akihide Kuwabara Tianren Zhang Prof. Kent J. Griffith Prof. Zhang Lin Prof. Liyuan Chai Prof. Hiroshi Kageyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(15):e202401779
The Li3MX6 compounds (M=Sc, Y, In; X=Cl, Br) are known as promising ionic conductors due to their compatibility with typical metal oxide cathode materials. In this study, we have successfully synthesized γ-Li3ScCl6 using high pressure for the first time in this family. Structural analysis revealed that the high-pressure polymorph crystallizes in the polar and chiral space group P63mc with hexagonal close-packing (hcp) of anions, unlike the ambient-pressure α-Li3ScCl6 and its spinel analog with cubic closed packing (ccp) of anions. Investigation of the known Li3MX6 family further revealed that the cation/anion radius ratio, rM/rX, is the factor that determines which anion sublattice is formed and that in γ-Li3ScCl6, the difference in compressibility between Sc and Cl exceeds the ccp rM/rX threshold under pressure, enabling the ccp-to-hcp conversion. Electrochemical tests of γ-Li3ScCl6 demonstrate improved electrochemical reduction stability. These findings open up new avenues and design principles for lithium solid electrolytes, enabling routes for materials exploration and tuning electrochemical stability without compositional changes or the use of coatings. 相似文献
128.
金孙均 王友宝 苏俊 颜胜权 李云居 郭冰 李志宏 曾晟 连钢 白希祥 柳卫平 山口英齐 久保野茂 胡钧 D.Kahl 郑孝顺 文俊永 寺西高 王宏伟 石山博信 岩佐直人 小松原哲郎 李二涛 张健 《原子核物理评论》2015,32(3):274-279
在日本东京大学CRIB 次级束装置上,用长气体靶开展了22Na+ α共振散射的厚靶实验研究。针对长气体靶实验中的两体运动学重构问题,提出了一套包括构建空间复杂几何关系、计算能量损失以及反应运动学的逐事件分析方法;对22Na+α共振散射的实验数据进行了重构分析,得到了Ec.m. = 4.2 ~ 5.4 MeV 区间22Na( α,α ) 的激发函数,从实验的激发函数中观测到了复合核26Al 5 个较为明显的共振峰。鉴于26Al 共振态的衰变模式比较复杂,本工作发现的26Al新共振态的能级性质有待进一步的理论分析。The 22Na+α resonant scattering is studied via a conventional thick target inverse kinematic method with an extended gas target. A data analysis method is proposed for the two-body reaction kinematic reconstruction, in which the spatial geometry, the reaction kinematics and the energy losses are considered. The experimental data of 22Na+ αresonant scattering have been thus reconstructed, and the excitation function is obtained in the energy interval of Ec.m. =4.2~5.4 MeV. Five resonant states in 26Al are observed in the experimental excitation function. Since several decay modes coexist for the observed 26Al resonant states, multi-channel theoretical analysis is thus needed to reveal their structure and decay features. 相似文献
129.
Miho Tanaka Kazuya Takahashi Tatsuya Urabe Tomohiro Oikawa Masao Nemoto Hideki Nagashima 《Rapid communications in mass spectrometry : RCM》2009,23(5):698-704
Silica, represented by SiO2, is the general name for the compounds composed of Si, O and H with their derivative complexes. Silica forms various chemical species in aquatic solutions, such as a monomer (Si(OH)3O−), dimer (Si2(OH)5O), and others. These species are known to vary in their relative abundances in solution depending on the chemical and physical conditions. Silica species dissolved in seawater have been examined by fast-atom bombardment mass spectrometry (FAB-MS) to elucidate the behavior of silica and its circulation as a novel tracer reflecting the chemical and physical conditions of seawater and the bioactivity of diatoms, which take up silica. In the seawater of Tokyo Bay, silica species such as [Si(OH)2O2Na]− ([monomer–Na]−), [Si2(OH)5O2]− ([dimer]−), [Si2(OH)4O3Na]− ([dimer–Na]−), [Si4(OH)7O5]− ([cyclic tetramer]−), [Si4(OH)6O6Na]− ([cyclic tetramer–Na]−), [Si4(OH)9O4]− ([linear tetramer]−) and [Si4(OH)8O5Na]− ([linear tetramer–Na]−) were observed and assigned by FAB-MS. To investigate the suitability of silica species as a tracer, the relative peak intensity ratios of silica species observed in the mass spectra, i.e. the profiles of the ratio of the linear tetramer to the cyclic tetramer (m/z 329/311) and the ratio of the dimer to the cyclic tetramer (m/z 173/311) against depth, were examined to determine the annual changes and reproducibility of the depth profiles. In particular, the depth profile of the relative ratio of the linear tetramer to the cyclic tetramer, 329/311, exhibits critical changes depending on the seawater budget. These changes in the relative ratios were identified by an experiment involving a simple sodium chloride solution system. Our measurement is expected to elucidate the dynamics of silica and its role as ‘food’ for diatoms, and we showed that speciation using mass spectrometry is a powerful tool for examining elemental behavior in nature and environmental changes. Our results suggest that a silica tracer is useful for investigating the behavior of seawater in small coastal regions and the uptake of silica by diatoms. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
130.
Tachikawa T Chung HR Masuhara A Kasai H Oikawa H Nakanishi H Fujitsuka M Majima T 《Journal of the American Chemical Society》2006,128(50):15944-15945
The growth dynamics of fluorescent perylene nanocrystals, which are fabricated by the reprecipitation method, was investigated using in situ and ex situ single-particle fluorescence measurements. A red shift in the emission maxima as the aging time increased was observed by single-particle fluorescence spectral measurements. The number and size of the nanocrystals increased with the increasing aging time in water. It was concluded that the metastable intermediates, such as clusters and initial nanoparticles, are relevant for the early stages of nucleation and growth of the perylene nanocrystals. 相似文献