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101.
Abstract It is observed that sodium phosphate polymers, in which some of the Na+ ions have been replaced by La3+ ions, are subject to both simple molecular flow and to bond interchange in the glass transition region. These two relaxation mechanisms are separated, and their relative contributions to the shear viscosity are calculated. It is shown that the bond-interchange mechanism is subject to an activation energy of ca. 50 kcal, while that of the molecular flow is of the order of 200 kcal at Tg + 30°C;the latter is of the WLF form. It is further shown that the La3+ ions act as cross-links, at least at low concentrations, and that bond interchange occurs at the site of the La3+ ions rather than at random along the polymer chain. 相似文献
102.
Vladimir Ya. Lee Shogo Miyazaki Hiroyuki Yasuda Akira Sekiguchi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):1346-1350
The reaction of trisilirene 1 with propylene sulfide or elemental sulfur produced Si3S-bicyclo[1.1.0]butane 2, which underwent Si–Si insertion of a second S atom forming Si3S2-bicyclo[1.1.1]pentane 3. Analogous reactions of 1 with elemental Se or Te resulted in the formation of heavier analogues of 2, namely, Si3Se-bicyclo[1.1.0]butane 4 and Si3Te-bicyclo[1.1.0]butane 5. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT 相似文献
103.
Kakue T Yonesaka R Tahara T Awatsuji Y Nishio K Ura S Kubota T Matoba O 《Optics letters》2011,36(21):4131-4133
Parallel phase-shifting digital holography can obtain three-dimensional information of a dynamically moving object with high accuracy by using space-division multiplexing of multiple holograms required for phase-shifting interferometry. We demonstrated high-speed parallel phase-shifting digital holography and obtained images of the phase variation of air caused by a compressed gas flow sprayed from a nozzle. In particular, we found the interesting phenomenon of periodic phase distributions. Reconstructed images were obtained at frame rates of 20,000 and 180,000 frames per second. 相似文献
104.
Hideyuki Nakanishi Yuto Kawabata Shogo Tsujiai Hayato Tanaka Satoshi Teraji Gbor Holl Istvn Lagzi Tomohisa Norisuye Qui Tran‐Cong‐Miyata 《Angewandte Chemie (International ed. in English)》2020,59(31):13086-13092
The development of methods to pattern nanocrystals with different sizes and shapes remains a challenge. In this study, we demonstrate a unique class of bottom‐up approaches to assemble nanocrystals into patterns. Our approach for patterning nanocrystals focuses on the utilization and control of the chemical reaction of solvents surrounding nanocrystals. The photopolymerization of solvent molecules through a photomask creates time‐dependent concentration gradients of the solvents. Dispersed nanocrystals such as silver nanowires (AgNWs) migrate and are gradually organized and integrated into the polymerizing films based on the concentration gradients. The AgNW‐embedded film properties are determined by the organized AgNW structures and include light transmission and electrical conductivity. Overall, the demonstrated method is very simple, widely applicable to various nanocrystals and solvents, and can thus contribute to the development of a new class of nanocrystal patterning methods. 相似文献
105.
Maruno Shigemitsu Iwasaki Hiroshi Horioka Keiji Li Sung-Te Nakamura Shogo 《Surface science》1982,123(1):18-28
We observed the hydrogen adsorption on the Si(001)2 × 1 surface achieved at room temperature by angle-resolved electron energy loss spectroscopy (AR-ELS) and elastic low-energy electron diffraction. From measurements of the intensities of elastically diffracted beams, we found a characteristic hydrogen covered surface (called Si(001)2 × 1H(RT) surface in this paper), where all the diffracted beam intensities were enhanced drastically and a sharp 2 × 1 LEED pattern was observed. The angular dependence of the elastically diffracted beams on the 2 × 1H(RT) surface was different from that on the monohydride 2 × 1:H surface. On the 2 × 1H(RT) surface the S3, transition from the back bond surface state disappeared in contrary to the 2 × 1:H surface and two hydrogen induced transitions were observed at 7.0 and 8.0 eV in AR-ELS spectra. We revealed that the 2 × 1H(RT) surface consisted of the monohydride and the dihydride phases with comparable weights. Additionally, we found the new transition S'1, ascribed to the newly produced dangling bond surface state due to the rupture of the dimerization bond with hydrogen adsorption. 相似文献
106.
107.
Shogo Aoyama 《Nuclear Physics B》1982,194(3):513-534
We shall observe that the renormalization of the string operator U(x1, x2; C) = Pexp{ig∫x1x2dxμAμ(x)} with an open path C (smooth and non-intersecting) is path-independently performed in any order of perturbation. To demonstrate this, the renormalization constants will be calculated up to order g4. Next the renormalization effect on the algebraic identity will be discussed and it will be proved that the renormalization preserves the algebraic identity in any order of perturbation if the paths C and are smoothly connected at x2. Finally, the string operator renormalization is extended to the case when the path C is smoothly closed (the Wilson loop operator). It is then shown that the renormalization factor which multiplicatively renormalizes the string operator in the case of the open path, is cancelled in any order of perturbation by the divergence appearing in the coincidence of the end points. As a results, the Wilson loop operator can be renormalized by the coupling constant renormalization alone. 相似文献
108.
Lee VY Miyazaki S Yasuda H Sekiguchi A 《Journal of the American Chemical Society》2008,130(9):2758-2759
Group 14 and 16 hybrid heavy bicyclo[1.1.0]butanes (tBu2MeSi)4Si3E (E = S, Se, and Te) 2a-c have been prepared by the [1 + 2] cycloaddition reaction of trisilirene 1 and the corresponding chalcogen. Bicyclo[1.1.0]butanes 2 have exceedingly short bridging Si-Si bonds (2.2616(19) A for 2b and 2.2771(13) A for 2c), a phenomenon explained by the important contribution of the trisilirene-chalcogen pi-complex character to the overall bonding of 2. Photolysis of 2a and 2b produced their valence isomers, the heavy cyclobutenes 3a and 3b, featuring flat four-membered Si3E rings and a planar geometry of the Si=Si double bond. The mechanism of such isomerization was studied using deuterium-labeled 2a-d6 to ascertain the preference of the pathway, involving the direct concerted symmetry-allowed transformation of bicyclo[1.1.0]butane 2 to cyclobutene 3. 相似文献
109.
Sonoluminescence spectra from argon-saturated NaCl solution were measured in the concentration range of 0.5-4 M at the frequency of 138 kHz. The line broadening of sodium atom emission was observed at various acoustic powers in the range from 1.8 to 16.2 W. The sodium D line showed a maximum intensity at a NaCl concentration of 2 M, which corresponded to the maximum production of OH radicals estimated by KI dosimetry. The effects of the addition of a small amount of ethanol on the line width and intensity were closely investigated at various acoustic powers. The sodium line width increases with ethanol concentration and also with power, whereas the line intensity is strongly quenched with increasing ethanol concentration. The results conclusively show that the sodium emission occurs in the gas phase within bubbles. The line broadening is due to interactions with high-pressure argon, and the maximum relative density of gas at bubble collapse was estimated to be 59.5 from the comparison with spectroscopic data. Further line broadening and quenching upon the addition of ethanol arise from collisions with gaseous products obtained from the decomposition of ethanol. The mechanism of sodium excitation is inferred to be as follows. Sodium ions enter bubbles as droplets, and salts are formed because of the high temperature within bubbles. Sodium atoms are generated by the dissociation of salts and then undergo electronic excitation by OH and H radicals. 相似文献
110.
Kawamoto T Ejiri S Kobayashi K Odo S Nishihara Y Takagi K 《The Journal of organic chemistry》2008,73(4):1601-1604
Pd-P(t-Bu)3 was found to be a chemoselective catalyst for the reaction of p-phenylenedizinc compound with equimolar amounts of carbon electrophiles to afford the single cross-coupling products in good yields, effectively suppressing the formation of double cross-coupling products. The subsequent additions of other electrophiles to the resulting solutions caused the second cross-coupling of the incipient products to take place, achieving a novel and efficient one-pot synthesis of unsymmetrically 1,4-disubstituted benzenes. The origin of the observed high chemoselectivity was speculated. 相似文献