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101.
Chuan-Lei Jia Xue-Lin Wang Lei Wang Ke-Ming Wang Hong-Ji Ma Rui Nie 《Applied Surface Science》2008,254(16):5095-5099
We report on the optical planar waveguides formation and modal characterization in β-BaB2O4 crystals by Ni2+ ion implantation at energy of 3.0 MeV and doses of 1014 ions/cm2. The prism coupling method was used to investigate the dark-mode property at wavelengths of 633 nm and 1539 nm, respectively. The refractive index profiles of the waveguides with different doses were reconstructed by an effective refractive index method based on the reflectivity calculation method (RCM). The modal analysis indicates that the fields of TM modes can be well restricted in the guiding region, which means the formation of non-leaky waveguide in the crystal. 相似文献
102.
LIU Yang-Kui FANG Jian-Hui PANG Ting LIN Peng 《理论物理通讯》2008,50(9):603-606
Two new types of conserved quantities deduced by Noether-Mei symmetry of nonholonomic mechanical system are studied. The definition and criterion of Noether-Mei symmetry for the system are given. A coordination function is introduced, and the conditions under which the Noether-Mei symmetry leads to the two types of conserved quantities and the forms of the two types of conserved quantities are obtained. An illustrative example is given. The coordination function can be selected according to the demand for finding the gauge function, and the choice of the coordination function has multiformity, so more conserved quantities deduced from Noether-Mei symmetry of mechanical system can be obtained. 相似文献
103.
利用ANSYS有限元软件计算了声波测井中使用的偶极子换能器在不同机械边界条件下的振动模态和频率响应。计算结果显示,偶极子换能器在一定的频率范围内有多个振动模态,不同的机械边界条件不仅影响振动模态的个数而且还影响同一振动模态的谐振频率;从频率响应曲线上还可以看出此结构的偶极子换能器在做弯曲振动时的频带较窄,这对在不同地层井眼中进行的偶极子声波测井非常不利。通过多个不同主频的偶极子换能器组合工作可以从根本上拓宽偶极声波换能器的频带宽度。 相似文献
104.
结合教师科研项目,推荐一个精细化工专业实验:疏水缔合聚合物的制备、表征及性能测定。通过该实验可以使学生掌握自由基共聚法制备聚合物的基本原理,掌握一些大型仪器的基本操作、聚合物常用的表征手段及结构分析方法,理解疏水缔合聚合物结构与性能之间深层次的理论联系。该实验项目来源于科研,服务于实践,集聚合反应、结构表征、大分子溶液理化性能测试于一体,具有综合性、前沿性、研究性等特点。本实验的开设有利于提高精细化工方向学生的专业实验水平,提升学生的综合探究素质、创新意识及动手能力。 相似文献
105.
设计了以柴油中饱和烃含量及碳数分布测定、聚丙烯酸高级醇酯(PTA)的合成与纯化、PTA的红外表征与分子量测定、PTA降凝性能评价等4个模块组成的综合实验,作为化工专业实验的考核及成绩评定平台。这种考核方式将过程考核与结果考核融合,将笔试、操作、设计融合,可以全面准确地考核学生的有机合成、仪器分析等基础实验技能,同时考核综述、数据处理、实验设计等综合实验能力和实验室工作素质。此外,还能够有效训练学生的学习能力、解决问题能力、实践能力和创新能力,并促进了实验教学水平提高。 相似文献
106.
Vinyl polymerizations of norbornene catalyzed by nickel complexes with acetoacetamide ligands 下载免费PDF全文
On the basis of a remote effect, a series of acetoacetamide ligands and corresponding nickel complexes N‐(R‐phenyl) acetoacetamide Ni(CH2Ph) (PMe3) (R = H, 1 ; R = 2‐methyl, 2 ; R = 2,6‐dimethyl, 3 ; R = 2,6‐diisopropyl, 4 ; R = 4‐NO2, 5 ) were synthesized and characterized. The solid structure of complex 3 was confirmed by X‐ray single‐crystal analysis to be of cis form. 1H and 31P NMR spectroscopy confirmed that cis and trans isomers of nickel complexes were present in solution. Norbornene polymerizations with acetoacetamide nickel complexes activated with modified methylaluminoxane (MMAO) were investigated in detail. Remote steric and electronic effects of acetoacetamide ligand on catalytic activity and molecular weight of polynorbornenes (PNBs) were observed. Characterizations of the obtained PNBs show that the obtained polymer products are non‐crystalline vinylic‐addition polynorbornenes. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
107.
以廉价水玻璃为硅源,在晶种替代有机模板剂的条件下采用干胶法合成了ZSM-5分子筛。利用XRD、SEM、TEM、FTIR、N_2吸附-脱附和NH_3-TPD等分析方法对合成样品进行了表征和测试,考察了合成条件对ZSM-5分子筛晶化过程的影响。结果表明,在硅铝比(n/n)为30~70,钠硅比(n/n)为0.12~0.20时都可以得到结晶度良好的ZSM-5分子筛。研究发现,干胶法合成ZSM-5,在不引入外加水的情况下也可以得到ZSM-5样品,外加水的引入能够有效地提高晶化速率;与水热法合成ZSM-5分子筛相比,干胶法可以显著地缩短晶化时间,同时,合成样品的晶体尺寸也有所减小。 相似文献
109.
Huanrong Liu Mengqi Zhuang Zhanquan Zhang Xiaodong Dai Ling Qian Zifeng Yan 《Chemical Papers》2018,72(8):1973-1979
Soot removal for exhaust gas from diesel engine has been addressed due to the more stringent legislation and environmental concerns. MnCo2O4 catalysts were systematically prepared using glucose as a fuel via the auto-combustion method and applied for soot removal. The as-prepared samples were characterized by X-ray diffraction (XRD), O2-temperature-programmed oxidation (TPO) reaction and H2-temperature-programmed reduction reaction (H2-TPR). The catalytic activities for soot combustion were evaluated by micro activity test (MAT) with a tight contact mode between soot and catalysts. Compared with catalysts prepared by the solid state method without glucose, auto-combustion method in the presence of glucose can decrease the synthetic temperature, avoiding high temperature treatment and sintering. The catalysts prepared with glucose could catalyze soot oxidation effectively and the derived values of T10, T50, and T90 were 326, 408, and 468 °C in a tight contact mode, respectively, showing a significant drop of T10, T50, and T90 by 156, 177, and 178 °C for non-catalytic reaction. 相似文献
110.
《中国化学快报》2023,34(2):107709
With the help of the redox mediator, decoupled water-splitting allows O2 and H2 to be produced at different times, at different rates, and even in different cells, which promotes both the operation safety and the utilization of renewable power sources. However, the current densities and stabilities of these redox mediators are commonly low, which require further improvements for practical applications. Here, we propose to use supercapacitors as solid state redox mediators for decoupled water splitting. For demonstration, Na0.5MnO2 (pseudocapacitor) and active carbon (double layer capacitor), are both used as the redox mediator. These supercapacitors show superior current density (1 A/cm2) and ultralong cycle-life (8000 cycles) compared with commonly investigated battery-based mediators (NiOOH/Ni(OH)2). Our research proves supercapacitors can be used as redox relay with high current density and stability, which may bring new insights in the design of decoupled water splitting systems. 相似文献