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41.
Devan RS Gao SY Lin YR Cheng SR Hsu CE Chen CH Shiu HW Liou Y Ma YR 《Microscopy and microanalysis》2011,17(6):944-949
Atomic force microscopy probe-induced large-area ultrathin SiO(x) (x ≡ O/Si content ratio and x > 2) protrusions only a few nanometers high on a SiO(2) layer were characterized by scanning photoemission microscopy (SPEM) and X-ray photoemission spectroscopy (XPS). SPEM images of the large-area ultrathin SiO(x) protrusions directly showed the surface chemical distribution and chemical state specifications. The peak intensity ratios of the XPS spectra of the large-area ultrathin SiO(x) protrusions provided the elemental quantification of the Si 2p core levels and Si oxidation states (such as the Si(4+), Si(3+), Si(2+), and Si(1+) species). The O/Si content ratio (x) was evidently determined by the height of the large-area ultrathin SiO(x) protrusions. 相似文献
42.
43.
Tzu‐Wei Tsai Eng‐Chi Wang Sie‐Rong Li Yung‐Hua Chen Yu‐Li Lin You‐Feng Wang Keng‐Shiang Huang 《中国化学会会志》2004,51(6):1307-1318
Based on Claisen rearrangement, the double bond isomerization of O‐allyl function together with the formation of O‐vinyl function in one pot, and ring‐closing metathesis (RCM), various phenols were transformed into various benzofurans in good yields. 相似文献
44.
R. S. Chen D. X. Wang Edward K. N. Yung 《International Journal of Infrared and Millimeter Waves》2004,25(1):197-211
The generalized minimal residual (GMRES) iterative method is applied to solve such sparse large non-symmetric system of linear equations resulting from the use of edge-based finite element method. In order to speed up the convergence of GMRES, the symmetric successive overrelaxation (SSOR) preconditioning scheme is applied for the analysis of millimeter wave ferrite circulator. Consequently, this preconditioned GMRES (PGMRES) approach can reach convergence ten times faster than GMRES. The reflection and insertion losses of millimeter wave waveguide circulator are compared with those obtained from literature. 相似文献
45.
R. S. Chen D. X. Wang Edward K. N. Yung 《International Journal of Infrared and Millimeter Waves》2003,24(7):1187-1202
The finite element method (FEM) combined with the perfectly matched layers (PML) is given for simulation of waveguide ferrite circulators. The generalized minimal residual (GMRES) iterative method is applied to solve such sparse large non-symmetric system of linear equations resulting from the use of edge-based finite element method. The formulation of FEM and the algorithm of GMRES method are described in detail. The reflection and insertion losses of millimeter wave waveguide circulator are analyzed and the results are compared with those obtained from literature. 相似文献
46.
The proton and neutron electric radii are calculated within QCD using the sum rules method for processes with small momentum transfers. The agreement with experimental values is good for the proton radius and somewhat poorer for the neutron one due to the numerical smallness. 相似文献
47.
K. C. Yung B. L. Zhu J. Wu T. M. Yue C. S. Xie 《Journal of Polymer Science.Polymer Physics》2007,45(13):1662-1674
Polymer matrix composites, based on brominated epoxy, a type of material widely used in printed circuit boards (PCBs), as matrix and AlN particle as filler were prepared. The influences of AlN content on the mechanical, thermal, and electrical properties of the composites were investigated by uniaxial tensile test, TMA, thermal conductivity measurement, DMA, and dielectric properties measurement. It was found that the properties of composites monotonically varied with AlN content except that maximum tensile strength and strain of composites corresponded to a filler content of 10 wt %. The results of DMA also showed the AlN reinforcement was more pronounced above Tg, and the peak area of tan δ versus T curves decreased with AlN content, which implied the damping capacity of the composite gradually decreased. The increase in Tg and decrease in damping were probably due to strong interaction between the AlN and epoxy matrix inhibiting the mobility of the epoxy chain. In addition, different theoretical models reported in the literature were used to predict the E, CTE, k, and Dk, and compared with the experimental data. Finally, suitable models were recommended in the present materials system. For the significant improvement of performance of epoxy, we can conclude that these composite materials may be promising for PCB substrate. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1662–1674, 2007 相似文献
48.
The structural phase transition in tin-modified zirconium titanate was investigated using high-temperature X-ray, DTA, DSC and electrical conductivity. In a dilute solid solution of Sn (x 0.2) in Zr1−xSnxTiO4, we ascribed to the successive phase transition from normal to incommensurate the break of electrical conductivity, thermal anomalies, and specific heat anomalies occurring at temperatures of 1121 °C, 1124 °C and 1125 °C on the heating run, and at temperatures of 1121 °C, 1116 °C and 1117 °C on the cooling run, respectively. Furthermore, the super-lattice reflection intensity was inversely proportional to the Sn content, cooling rate and electrical activation energy. With a composition of Zr0.8Sn0.2TiO4, the phase transition from normal to incommensurate was completely inhibited. 相似文献
49.
A new experimental approach is proposed for the evaluation of liquid junction potentials and single ion activities. Neither of these quantities can be experimentally measured without assumption. Furthermore, they are concentration dependent but without clearly defined functional relationships. Thus, a given assumption may be satisfactory to obtain these quantities at a given concentration, but will fail at another concentration. It is the intent of this paper to establish a functional relationship between the ratio of activity coefficients and the ionic strength, through which the liquid junction potentials may be computed, as well as the pH values at moderate ionic strengths (<1.0 m). Experimental results are presented and uncertainties are discussed. 相似文献
50.
George A. Grindahl John R. Greenwald Louis H. Troporcer Ogden R. Pierce Yung K. Kim 《Journal of polymer science. Part A, Polymer chemistry》1974,12(7):1559-1564
Four new s-triazine polymers were prepared by the mercury-induced coupling of bromodifluoromethyl-substituted ditriazinyl-perfluoroalkane derivatives. Each polymer was composed of CF3-substituted s-triazin rings alternately joined with ? CF2CF2? segments and \documentclass{article}\pagestyle{empty}\begin{document}$\hbox{---}\hskip-5pt({\rm CF}_2 )_8 \hbox{---}$\end{document}, a mixture of ? (CF3CFO(CF2)5OCF(CF3)? and ? (CF3)CFOCF2CF(CF3)OCF2)4? , ? CF2OCF2? , or ? CF2SCF2? , segments. All polymers were elastomeric and displayed high temperature stability on thermogravimetric analysis. The polymers containing either ? CF2OCF2? or ? CF2SCF2? segments showed high temperature limits slightly lower than the other two systems. 相似文献