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41.
This paper details developments in the CO2 laser cutting of thick ceramic tiles, that is thicknesses of 8.5 mm and 9.2 mm. These tiles were cut at a combination of different cutting speeds to determine the necessary cutting parameters for various tile geometries. Different cutting modes were used in conjunction with different cutting speeds to investigate cut quality after laser processing. The work also looked into the effects on cutting through using various shield gases. Multipass cutting and underwater cutting were performed to examine their effects on thermal load during processing. 相似文献
42.
Use is made of computer simulated turbulent signals to calculate the rms of the velocity cone angle. The calculation compares
favourably with X-probe data close to the axis of a circular jet. In this flow, the vector cone angle can exceed 90°, even
on the axis. As a consequence, the rms values of the cone angle and of the lateral velocity fluctuation can be seriously underestimated
with a 90° X-probe. Support for this is provided by measurements with a 120° X-probe. 相似文献
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The thermochemistry of bicyclic lactams (penams, penems, cephams, cephems), which are key pharmacophores in beta-lactam antibiotics, has been investigated by high-level ab initio methods. Particular attention has been paid to estimating magnitudes of amide resonance (ARE) and ring strain (RSE) in the four-member lactam ring because these quantities are difficult to measure and distinguish experimentally. The ring strain destabilization effect is greater than the stabilization arising from amide resonance. However, in cephemes the amide resonance stabilization slightly exceeds destabilization due to the beta-lactam ring strain. 相似文献
47.
Jeun Kee Chua 《Optics Communications》2010,283(1):169-175
Resonant amplification and enhancement of evanescent wave’s frustration across an optical barrier by using single dielectric coating is numerically demonstrated in this article. With further tuning of the thickness values of the second and the third medium (optical barrier) of the proposed stratified four-media configuration, it is shown that it may be possible to achieve unity transmittance at discrete, but closely spaced incident angles within the full range defined by the theoretical cut-off limit. The designed configuration may have other potential applications than lithography and waveguide design is one such example. 相似文献
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S.T. Tan X.W. Sun X.H. Zhang B.J. Chen S.J. Chua Anna Yong Z.L. Dong X. Hu 《Journal of Crystal Growth》2006,290(2):518-522
Zinc oxide (ZnO) quantum dots (QDs) were fabricated on silicon substrates by metal organic chemical vapor deposition. Formation of QDs is due to the vigorous reaction of the precursors when a large amount of precursors was introduced during the growth. The size of the QDs ranged from 3 to 12 nm, which was estimated by high-resolution transmission electron microscopy. The photoluminescence measured at 80 K showed that the emission of QDs embedded film ranged from 3.0 to 3.6 eV. The broad near-band-edge emission was due to the quantum confinement effect of the QDs. 相似文献
50.
The NO catalytic direct decomposition was studied over La2CuO4 nanofibers, which were synthesized by using single walled carbon nanotubes (CNTs) as templates under hydrothermal condition. The composition and BET specific surface area of the La2CuO4 nanofiber were La2Cu0.882+Cu0.12+O3.94 and 105.0 m2/g, respectively. 100% NO conversion (turnover frequency-(TOF): 0.17 gNO/gcatalyst s) was obtained over such nanofiber catalyst at temperatures above 300 °C with the products being only N2 and O2. In 60 h on stream testing, either at 300 °C or at 800 °C, the nanofiber catalyst still showed high NO conversion efficiency (at 300 °C, 98%, TOF: 0.17 gNO/gcatalyst s; at 800 °C, 96%, TOF: 0.16 gNO/gcatalyst s). The O2 and NO temperature programmed desorption (TPD) results indicated that the desorption of oxygen over the nanofibers occurred at 80-190 and 720-900 °C; while NO desorption happened at temperatures of 210-330 °C. NO and O2 did not competitively adsorb on the nanofiber catalyst. For outstanding the advantage of the nanostate catalyst, the usual La2CuO4 bulk powder was also prepared and studied for comparison. 相似文献