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91.
采用机械球磨法制备Y~(3+)修饰TiO_2光催化剂,利用紫外-可见漫反射光谱(UV-Vis DRS)、X射线光电子能谱(XPS)、X射线粉末衍射(XRD)、扫描电镜(SEM)等对其进行表征,在紫外光下,以亚甲基蓝(MB)为去除物来考察催化剂活性并优化球磨工艺。将最佳条件下制得的Y~(3+)/TiO_2光催化剂负载于不同半径的塑料浮球上,分别在紫外光和模拟太阳光照射下处理海水养虾废水,通过CODCr(chemical oxygen demand)及三维荧光观察有机物含量变化。结果表明,当Y~(3+)的物质的量分数为2%,球磨时间4 h,球料质量比4∶1,转速为500 r·min~(-1)时,MB光催化降解反应速率常数可达0.111 3 min~(-1),是纯TiO 2的4.2倍。由UV-Vis DRS、XPS、N_2吸附-脱附、XRD、SEM等表征结果显示,2%Y~(3+)/TiO_2样品的禁带宽度降低至3.05 eV,光吸收发生红移,并产生可见光响应,表面吸附氧含量明显增加,比表面积增大到104 m~2·g~(-1)。采用纯TiO_2及2%Y~(3+)/TiO_2为光催化剂处理养虾废水,在可见光和紫外光下CODCr的去除率分别为14.7%和18.8%、26.9%和37.5%。考察3种直径分别为1、2、3 cm负载Y~(3+)/TiO_2浮球的光催化效果,显示直径为2 cm浮球效果最佳,CODCr去除率可达38.5%。 相似文献
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采用球磨法制备了La_2O_3和离子态La掺杂TiO_2光催化剂,以300 W中压汞灯为光源,亚甲基蓝溶液为模拟废水,考察了掺杂比和球磨时间对样品光催化活性的影响。结果表明,当催化剂加入量为0.2 g·L~(-1),亚甲基蓝初始浓度为25 mg·L~(-1),La_2O_3和La~(3+)掺杂的最佳摩尔比分别为0.5%和3%,球磨时间为4个小时,La_2O_3/TiO_2,La~(3+)/TiO_2和纯TiO_2的一级反应速率常数k分别可达最大值为0.0467 min~(-1),0.0643 min~(-1)和0.0263 min~(-1)。 相似文献
95.
Influence of tube voltage and current on in-line phase contrast imaging using a microfocus x-ray source
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In-line x-ray phase contrast imaging has attracted much attention due
to two major advantages: its effectiveness in imaging weakly
absorbing materials, and the simplicity of its facilities. In this
paper a comprehensive theory based on Wigner distribution developed
by Wu and Liu [Med. Phys. 31 2378-2384 (2004)] is reviewed. The
influence of x-ray source and detector on the image is discussed.
Experiments using a microfocus x-ray source and a CCD detector are
conducted, which show the role of two key factors on imaging: the
tube voltage and tube current. High tube current and moderate tube
voltage are suggested for imaging. 相似文献
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采用美国军用标准MIL-PRF-13830B(简称美标)对光学元件表面疵病进行数字化评价,其难点主要在于美标中表面疵病密集度的判定。针对该难点,提出了一种表面疵病密集度判定算法。该算法采用权重域叠加的方法,通过为表面疵病赋予相应的权重域来确定疵病密集圆域,并将权重域间的叠加转换成了矩阵间位置关系的判断和计算,有效的利用了矩阵运算的便利性。实验中通过对已知表面疵病信息的石英标准板进行判定,其得到的圆域即为疪病密集圆域,与预期结果一致,验证了该算法的正确性。目前该算法已经运用于光学车间精密光学元件表面疵病的美标数字化评价。 相似文献
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Single crystalline boron nanocones are prepared by using a simple spin spread method in which Fe 3 O 4 nanoparticles are pre-manipulated on Si(111) to form catalyst patterns of different densities.The density of boron nanocones can be tuned by changing the concentration of catalyst nanoparticles.High-resolution transmission electron microscopy analysis shows that the boron nanocone has a β-tetragonal structure with good crystallization.The field emission behaviour is optimal when the spacing distance is close to the nanocone length,which indicates that this simple spin spread method has great potential applications in electron emission nanodevices. 相似文献
99.
Surface-enhanced Raman scattering properties of highly ordered self-assemblies of gold nanorods with different aspect ratios
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Gold nanorods with aspect ratios of from 1 (particles) to 31.6 were synthesized by the seed-mediated method and packed in a highly ordered structure on a large scale on silicon substrates through capillary force induced self-assembly behaviour during solvent evaporation.The gold nanorod surface exhibits a strong enhancing effect on Raman scattering spectroscopy.The enhancement of Raman scattering for two model molecules (2-naphthalenethiol and rhodamine 6G) is about 5-6 orders of magnitude.By changing the aspect ratio of the Au nanorods,we found that the enhancement factors decreased with the increase of aspect ratios.The observed Raman scattering enhancement is strong and should be ascribed to the surface plasmon coupling between closely packed nanorods,which may result in huge local electromagnetic field enhancements in those confined junctions. 相似文献
100.
设计制备了以泊洛沙姆407/188为主要基质,卡波姆、氯化钠为添加剂,月桂酸二乙醇酰胺为增溶剂的双氯芬酸钠缓释液体栓,以凝胶温度、凝胶强度、生物黏附力和体外释放度为考察指标进行体外评价;测定双氯芬酸钠缓释液体栓在犬体内的血药浓度,进行体内筛选.采用3p97软件计算液体栓相关药动学参数,进行体内释药特性研究.加入0.9%月桂酸二乙醇酰胺使双氯芬酸钠增溶2.3倍.缓释液体栓体外释放符合零级模式,R20.9,释药时限大于6h;体内药物释放出现血药平台,具有良好的体内外相关性;体内过程为一室模型,t1/2(Ke)=5.553 3h,t1/2(Ka)=0.357 4h,cmax=7 712ng.mL-1,AUC0→∞=72 029ng.h.mL-1,MRT=7.61h.所制备的双氯芬酸钠缓释液体栓具有稳定的缓控释特性. 相似文献