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101.
The fluorescence properties of a series of rare earth (Re3+ = Eu3+, Tb3+) polymeric complexes (PEK-Re3+-HLs) using three high-Tg novel carboxyl-containing polyaryletherketones (PEK) as macromolecular ligands and small molecules (HL) such as 1,10-phenanthroline (Phen), dibenzoylmethane (DBM) and 8-hydroxyquinoline (HQ) as co-ligands were investigated by means of fluorescence excitation and emission spectroscopy as well as fluorescence lifetime measurement methods. Among them, PEK-1-Re3+-Phens, in which the Re3+ ions were coordinated simultaneously with Phen and PEK-1 containing both carboxyl and bulky isopropyl groups on the polymer backbone, exhibited strong fluorescence intensities, long lifetimes, and good film-formation properties. The smooth films of PEK-1-Eu3+-Phen and PEK-1-Tb3+-Phen, cast from their DMF solutions, could emit bright red and green light under the UV lamp of 365 nm, respectively, which characteristics are of great significance for their potential applications in the large area display material fields. The excellent fluorescence properties of complexes in this study were attributed to the synergistic effects of PEK-1 ligand and Phen co-ligand. Especially, the rigid twisted structure and the bulky isopropyl substituents on PEK-1 backbone forced the coordinated rare earth ion moieties apart, and thus the probability of non-radiative decay rate of Re3+ ions at the excited levels were decreased to a large extent. 相似文献
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104.
Several rare earth‐doped, calcium‐based magnetic catalysts were prepared for the synthesis of glycerol carbonate. The basicity and basic strength analysis of the catalysts showed that the doping of rare earth improved the basicity of the catalysts, and the doping of lanthanum maximized it. In addition, with the doping of lanthanum, the particle size of the catalyst became smaller to promote the organic reactants near the active sites of catalysts, thereby effectively improving the performance. NiFe2O4@[CaO‐La2O3] shows better catalytic performance with 99.0% yield of glycerol carbonate compared to the other catalysts. The NiFe2O4@(CaO‐La2O3) could be reused in six cycles without significant loss in activity. 相似文献
105.
自抗扰控制技术在捷联惯导动基座初始对准中的应用研究 总被引:1,自引:1,他引:1
提出并设计了应用自抗扰控制技术(ADRC)的捷联惯性系统动基座初始对准方案。通过数字仿真,将卡尔曼滤波与自抗扰控制的性能进行了详细的比较,证明该方法具有对准时间快,精度高,抗干扰能力强等特点。 相似文献
106.
The presence of heavy metals in water bodies is linked to the increasing number of industries and populations. This has serious consequences for the quality of human health and the environment. In accordance with this issue, water and wastewater treatment technologies including ion exchange, chemical extraction, and hydrolysis should be conducted as a first water purification stage. However, the sequestration of these toxic substances tends to be expensive, especially for large scale treatment methods that require tedious control and have limited efficiency. Therefore, adsorption methods using adsorbents derived from biomass represent a promising alternative due to their great efficiency and abundance. Algal and seaweed biomass has appeared as a sustainable solution for environmentally friendly adsorbent production. This review further discusses recent developments in the use of algal and seaweed biomass as potential sorbent for heavy metal bioremediation. In addition, relevant aspects like metal toxicity, adsorption mechanism, and parameters affecting the completion of adsorption process are also highlighted. Overall, the critical conclusion drawn is that algae and seaweed biomass can be used to sustainably eliminate heavy metals from wastewater. 相似文献
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109.
以往的理论在预测六方结构(HCP)金属的表面能时,计算值与实验值存在较大误差.鉴于此,本文首先用一种较为合理的方法精准地预测了稀有金属钇(Y)(0001)面的表面能,计算值(1.141 J/M2)与实验值(1.125 J/M2)吻合的很好.随后,系统研究了NO小分子在Y(0001)面不同位置(空位、桥位和端位)的吸附行为.结果表明:空位(H1)表现出了良好的吸附能力,吸附能超过了5eV,同时N-O键长伸长量超过了24%,此时,NO分子几乎平行地吸附于Y(0001)表面.所有的吸附位置的N-O分子伸长量范围为0.2?-0.42?.这种伸长量明显超过了NO在其它金属表面时的计算结果. 相似文献
110.
We have carried out some photon interaction measurements using 59.54 keV γ-rays from a 241Am source. These include γ attenuation studies as well as photoelectric absorption studies in various samples. The attenuation
studies have been made using leaf and wood samples, samples like sand, sugar etc., which contain particles of varying sizes
as well as pellets and aqueous solutions of rare earth compounds. In the case of the leaf and wood samples, we have used the
γ-ray attenuation technique for the determination of the water content in fresh and dried samples. The variation of the attenuation
coefficient with particle size has been investigated for sand and sugar samples. The attenuation studies as well as the photoelectric
studies in the case of rare earth elements have been carried out on samples containing such elements whose K-absorption edge
energies lie below and close to the γ-energy used. Suitable compounds of the rare earth elements have been chosen as mixture
absorbers in these investigations. A narrow beam good geometry set-up was used for the attenuation measurements. A well-shielded
scattering geometry was used for the photoelectric measurements. The mixture rule was invoked to extract the values of the
mass attenuation coefficients for the elements from those of the corresponding compounds. The results are consistent with
theoretical values derived from the XCOM package. 相似文献