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151.
以FeCl_3·6H_2O为Fe源,采用水热法制备了Fe掺杂锐钛型TiO_2(A-Ti O2)光催化剂。以溴甲酚绿为降解对象,考察溴甲酚绿的初始浓度、催化剂用量、掺Fe量等因素对自制催化剂可见光催化降解反应的动力学方程的影响。结果表明:在40 W白炽灯照射下,当溴甲酚绿初始浓度为10 mg/L(pH=7)、催化剂的用量为0.6 g/L、掺Fe量为4%(摩尔分数)、室温下反应时间为3 h时,溴甲酚绿的降解率最大为76.05%。溴甲酚绿光催化降解曲线符合一级反应动力学方程,于上述最佳条件下其表观反应速率常数k达到最大值,为0.389 7 h-1。 相似文献
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153.
Zongqiang Yu Songting Tan Yingping Zou Benhu Fan Zhuliang Yuan Yongfang Li 《应用聚合物科学杂志》2006,102(4):3955-3962
Two novel copolymers of polyfluorenes/poly(p‐phenylenevinylene)s copolymers with p‐tert‐butyl‐phenylenemethylene groups in the C‐9 position of alternating fluorene unit, poly[1,4‐(2,5‐dibutyloxyl)‐phenyleneviny lene‐alt‐9‐(p‐tert‐butyl‐phenylenemethylene)fluorene] and poly[1,4‐(2,5‐dioctyloxyl)‐phenylenevinylene‐alt‐9‐(p‐tert‐butyl‐phenylenemethylene)fluorine], have been synthesized via the Heck polycondensation reaction. The synthesized polymers were characterized by FTIR, NMR, DSC, TGA, UV–vis, and PL spectra. The polymers showed high glass transition temperatures and good thermal stability. A polymer light‐emitting diode with the configuration ITO/PEDOT:PSS/P2/Ca/Al has been fabricated. The device emitted a yellow light with a peak wavelength of 578 nm similar to the PL spectra of the copolymer film. A maximal luminance of 534 cd/m2 was obtained at a driving voltage of 24.5 V. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3955–3962, 2006 相似文献
154.
Failure mechanisms in infiltrated carbon fiber felts have been studied by optical light microscopy, transmission electron microscopy and scanning electron microscopy combined with mechanical testing experiments. A model is presented which describes crack generation and propagation at layer-layer and fiber-matrix interfaces as well as within matrix carbon layers with different textures. Intensive cracking occurs within high- and less frequently in medium- and low-textured pyrolytic carbon layers. In particular, fracture does not occur directly at the fiber-matrix interface but within the low-textured matrix layer deposited on the fiber. Crack deflection in interface regions between layers with different textures, crack deflection along boundaries of columnar grains in high -textured layers and at interfaces between polyhedral nanoparticles, and finally crack bridging within high -textured lamellae are cooperative failure mechanisms contributing to the toughness enhancement. 相似文献
155.
根据交通信号灯灯板颜色和形状定位图像中的灯板位置. 将灯板区域的彩色图像转换到YCbCr 空间, 分割灯板区域中的红、黄、绿三色区域, 利用交通信号灯的形态特性定位交通灯位置. 用Gabor 小波和2 维独立分量分析提取感兴趣区域的特征, 送入最近邻分类器分类信号灯的类型. 用代表性的观测序列建立隐马尔科夫模型, 并结合识别和跟踪结果估计信号灯状态. 实验结果表明, 该算法能可靠、准确地识别出信号灯, 并有效地估计出信号灯的状态. 相似文献
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157.
Multi‐angle laser light scattering (MALLS) was used to characterize birch kraft pulps with respect to their absolute molecular mass distributions (MMDs). The pulps were dissolved in lithium chloride/N,N‐dimethylacetamide and separated by size exclusion chromatography (SEC). The weight‐average and number‐average molecular masses of the cellulose fractions of the pulps obtained from the absolute MALLS measurements were compared with the molar masses obtained by direct‐standard‐calibration relative pullulan standards. Discrepancies between the two detection methods were found, and two ways of correlating the relative pullulan molar masses to the absolute molar masses were examined. In the first method, the correlation was made over a large range of molecular masses. The second method correlated the molecular masses of the standards to the molecular masses of samples by the calculation of fictitious, cellulose‐equivalent molar masses of the standards. With the preferred second method, a more correct MMD of kraft pulp samples could, therefore, be obtained from an SEC system calibrated with narrow standards. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1170–1179, 2003 相似文献
158.
The random cross-linking of appropriately functionalized polystyrene in semi-dilute toluene solution (c = 0.01–0.05 g/mL) was studied by time-dependent measurements of dynamic light scattering. Macroscopic gelation occurred from concentrations as low as 0.02 g/mL. The gelation time, determined from the first appearance of fluctuations of the scattering intensity and the initial amplitude of the intensity correlation function (ICF), decreases markedly from about 100 min to 10 min with an increase of polymer concentration or cross-linker content. After the gel point, the ICFs display a characteristic power-law decay. The power-law exponent, n = 0.75 ± 0.06, does not change with (i) extent of reaction, (ii) polymer concentration, and (iii) cross-linker concentration, within the inspected ranges. This universal behavior is traced back to the fact that gelation took place as a result of random cross-linking of existent macromolecules, whose state of solution does not change markedly during conversion. 相似文献
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160.