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991.
Ganbat Duvjir Seung Mi Lee Otgonbayar Dugerjav Chu Van Chiem Jae M. Seo 《Surface science》2009,603(15):2312-4607
Using scanning tunneling microscopy (STM), it has been found that the reconstruction of Si(1 1 4) is transformed irreversibly from a 2 × 1 structure composed of dimer (D), rebonded atom (R), and tetramer (T) rows (phase A) to a different kind of 2 × 1 structure composed of D, T, and T rows (phase B) by C incorporation. It has been confirmed by high-resolution synchrotron core-level photoemission spectroscopy (PES) that such an irreversible structural transformation is due to stable subsurface C atoms. They induce anisotropic compressive stress on the surface, which results in insertion of Si dimers to an R row to form a T row. 相似文献
992.
In this paper, we propose a modified smart pixel mapping (MSPM) method for displaying orthoscopic three-dimensional (3D) images with a function of depth control in integral imaging system. In the proposed MSPM, the depth-converted elemental image array (EIA) is obtained through the pixel mapping process and the image interpolation technique. The proposed method gives us the depth conversion at distances different from the position of 3D object and provides various types of EIAs using only an original EIA for orthoscopic images. To show the usefulness of the proposed method, we carry out the preliminary experiments and present the experimental results. 相似文献
993.
Kiyoshi Matsumoto JongChul Kim Hirokazu Iida Hiroshi Hamana Koji Kumamoto Hiyoshizo Kotsuki Grard Jenner 《Helvetica chimica acta》2005,88(7):1734-1753
For the first time, uncatalyzed, high‐pressure (0.6 GPa) reactions with ketones have proven to be a powerful way to perform the three‐component Strecker synthesis of α‐amino nitriles in high yields. Two types of double Strecker reactions were achieved, but attempts to perform triple Strecker reactions were unsuccessful. 相似文献
994.
995.
In pursuit of photo‐curable adhesive for optical communication, dual‐curable acrylic oligomers (AOs) having alkoxy silane group, fluorine atoms and vinyl group as a pendent group were synthesized by two‐stage reactions. The isocyanate group containing oligomers were firstly synthesized via radical polymerization of acrylic monomers, and followed by urethane reaction with 2‐hydroxy ethyl methacrylate. The dual curing behaviors, e.g. thermal and photo‐cure, were studied by using photo‐differential scanning calorimetry (DSC) and real‐time IR. An optimum adhesive formulation, based on AO (15 g), epoxy acrylate (80 g), isobonyl methacrylate (17 g) and photo‐initiator (3 g), was obtained. As the content of AO was increased in the optical adhesive formulation, refractive index decreased but transmittance increased due to the increase in fluorine content. The optical transmittance at the range of 1.3 to 1.55 μm was higher than 90%. The addition of colloidal silica with the earlier mentioned formulation was helpful in decreasing crosslinking volume shrinkage and the increasing of glass fiber adhesion. The required properties for the optical adhesive, including chemical resistance and thermal resistance, dimension stability, etc. were also investigated. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
996.
Ag-doped polyaniline (PANI) nanoparticles are prepared via doping-dedoping-redoping with the thiol group in mercaptosuccinic acid (MSA) providing the linkage between PANI molecules and Ag atoms. Ag-MSA-doped PANI maintains the electrical conductivity well above the room-temperature value of 3.0 S/cm up to 220 °C, reaching its maximum (9.0 S/cm) at 180 °C. In addition, Ag-MSA-doped PANI nanoparticles show remarkable stability against repeated thermal aging at 120 °C. The room-temperature conductivity, in fact, increases by a factor of ∼3 after 3 cycles of thermal aging. The enhanced stability against repeated thermal aging is attributed to the formation of uniformly distributed Ag nanoparticles within the PANI particles upon heating. 相似文献
997.
We successfully modified organic clays containing the urethane group by introducing a covalent bond between the silanol group on the clay side and the hydroxyl group of organic modifier in the silicate layer using 1,6-diisocyanatohexane (HDI), namely surface-treated montmorillonite (30BM), to increase both basal spacing and the favorable interaction between clay and polymer. The effect of the surface urethane modification of clay on poly (butylene succinate) (PBS)/30BM nanocomposites was studied. The results of transmission electron microscopy micrographs at a 10-nm resolution and X-ray diffraction measurements allowed us to examine the degree of the high exfoliation and the effect of surface urethane modification on clay dispersibility. As results of high exfoliation, PBS/30BM nanocomposites not only exhibited the high thermal properties, but also showed a remarkable increase in physical properties (e.g., tensile strength, Young's modulus, elongation at break) due to enhanced affinity between the clay and PBS matrix. Over all, the results suggest that wide gallery spacing and the predominant affinity between PBS and clay must be considered simultaneously to increase the degree of exfoliation and physical properties as key factors. 相似文献
998.
Synthesis, photophysical, and complexation properties of fluorescent chemosensors, L1 and L2, with ‘receptor-spacer-fluorophore’ motif (L1: NS2O2-cyclic receptor, L2: acyclic analogue receptor) are described. Maximum chelation-enhanced fluorescence effect (TURN-ON type) was observed in the presence of Ag+ for both fluoroionophores in a 1:1 (v/v) aqueous ethanol solution: remarkably superior selectivity of L1 (150-fold) with cyclic receptor than that of the L2 (50-fold) with acyclic analogue was found. According to the fluorescence and NMR titrations, the excellent selectivity of L1 is attributed to its topology-based higher affinity in complexation. 相似文献
999.
Hyun Seung Lee 《Tetrahedron letters》2009,50(47):6480-6483
The reaction of Baylis-Hillman acetates and ethyl mercaptoacetate in the presence of DBU in DMF produced 2,3,4-trisubstituted tetrahydrothiophenes at room temperature as a diastereomeric mixture via the sequential SN2′ and Michael addition. Aromatization of tetrahydrothiophenes by DDQ oxidation produced 2,3,4-trisubstituted thiophenes in good yields. 相似文献
1000.
A convenient and selective halogenation of 4-(pyrazol-4-yl)-pyrimidines is described herein. This method allows quick access to a diverse set of pyrazolyl-pyrimidine derivatives. 相似文献