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941.
A facile route to the synthesis of γ-sulfonyl lactones 5 and β-sulfonyl styrenes 6 has been developed, achieving moderate to good yields via the (1) NaH mediated Michael addition of β-ketosulfones 3 and methyl acrylate in refluxing THF and (2) NaBH4 mediated stereoselective reduction/lactonization of δ-ketoesters 4 in boiling MeOH, or (3) boron trifluoride etherate mediated ring-opening of lactones 5 in MeOH at reflux. 相似文献
942.
We demonstrate high-efficiency, wideband-tunable, laser-ablated long-period fiber gratings that use an optical polymer overlay. Portions of the fiber cladding are periodically removed by CO(2) laser pulses to induce periodic index changes for coupling the core mode into cladding modes. An optical polymer with a high thermo-optic coefficient with a dispersion distinct from that of silica is used on a deep-ablated cladding structure so that the effective indices of cladding modes become dispersive and the resonant wavelengths can be efficiently tuned. The tuning efficiency can be as high as 15.8 nm/ degrees C, and the tuning range can be wider than 105 nm (1545-1650 nm). 相似文献
943.
944.
The nanostructure of a biomaterial surface has strong influence on cell behavior. The migration of cells on nanostructured surfaces, however, has not been investigated so far. In this study, we used PCL/PEG diblock copolymers as model surfaces to examine the effect of nanoislands on migration of different cells, including fibroblasts and endothelial cells. The water sliding angle of the substrates was measured. The cell migration rate was examined under a real-time optical microscope. It was found that a greater cell migration rate correlated with the smaller sliding angle of the substrate. 相似文献
945.
Yan‐Fu Chen Chang‐Long Kao Jyun‐Fu Yang Ping‐Chih Huang Ching‐Yun Hsu Chun‐Hsiung Kuei 《中国化学会会志》2015,62(9):766-771
A simplified extraction method was developed for extracting high molecular weight polycyclic aromatic hydrocarbons (PAHs) from river sediments. The samples were extracted 3 times with 5 mL of solvent (toluene:methanol, 9 : 1, v/v) at 100 °C, 10 minutes for each extraction. After clean‐up and concentration, extracts were analyzed by gas chromatography coupled with mass spectrometer (GC‐MS). The extraction efficiency and accuracy was evaluated by the standard reference material (SRM‐1941b). Comparing to certified values, the average recoveries of high molecular weight PAHs with 3, 4, 5 and 6 fused benzene rings were 72.9∼113.2 % (R.S.D. 2.3∼6.3 %) except those of dibenz[a,h]anthracene (206.2±4.6 %). The average recoveries for PAHs spiked sediment samples were comparable with accelerated solvent extraction (ASE) and Soxhlet methods. The simple extraction method consumes less solvent, fewer amount of sample than those of conventional methods. The lowest quantitation limit of PAHs is 1.1 μg/kg. 相似文献
946.
Extraction of Intercalated O2 from Aligned Carbon Nanotubes: The Breaking of Intertube Paths and Exponential Changes in Resistance 下载免费PDF全文
Hsin Jung Tsai Wen Yi Lin Wei Chin Tsung Ying Tsai Prof. Wen Kuang Hsu 《Chemphyschem》2015,16(12):2625-2629
In carbon nanotube films, the alignment of carbon nanotubes creates Lennard–Jones potentials at intertube junctions and trapped O2 appears to oscillate at elevated temperatures. Electrical measurements reveal a low hopping barrier along the transverse direction and an underlying mechanism that involves intercalated molecules acting as charge carriers between tubes. Ab initio calculations support dynamic intercalation and charge transfer through O2 bouncing between tubes. 相似文献
947.
Hung-Chu Hsu 《Journal of Mathematical Fluid Mechanics》2014,16(3):463-471
We present an exact solution of the nonlinear governing equations for internal geophysical water waves propagating westward in the f-plane approximation near the equator. We show that the mass transport velocity induced by this internal equatorial wave is eastward. 相似文献
948.
The optical system lens temperature difference will cause optical aberration increase. This study is applying finite element method (FEM) and optical ray tracing; calculate off axis ray thermal optical path difference (OPD). The optical system temperature distribution is calculated from finite element simulation result and weighting temperature to each optical ray path. The simulation result shows off-axis ray major thermal optical aberrations are tilt and piston at this study. 相似文献
949.
A synthesis of fully substituted cyclopentanes bearing a quaternary carbon center and five contiguous stereogenic centers has been achieved by sequential organocatalyzed Stetter and Michael-Aldol reactions of heteroaromatic aldehydes, nitroalkenes, and α,β-unsaturated aldehydes via the [1 + 2 + 2] annulation strategy with dynamic kinetic asymmetric transformation and excellent enantioselectivities (up to >99% ee). 相似文献
950.
This paper presents a mathematical study for the Bragg scattering of water waves propagating over a series of rectangular poro-elastic submerged breakwaters. Based on the linear wave theory and the improved Biot's theory of poro-elastic media with suitable matching conditions, an analytical solution was obtained as a function of elasticity, permeability and geometry of the submerged breakwaters. Experiments were also conducted in a wave flume to verify the present analytical study. In addition, the Bragg resonances for different influence parameters were studied. Satisfactory agreement between the theoretical predictions and the laboratory observations demonstrates the applicability of the present analytical result. 相似文献