The molten mixtures of alkali metal fluorides and aluminum fluoride are applied as aluminum electrolytes or brazing fluxes.However,the presence of Al2F-7^-in such molten systems is disputed.In the present study,MF-AlF...The molten mixtures of alkali metal fluorides and aluminum fluoride are applied as aluminum electrolytes or brazing fluxes.However,the presence of Al2F-7^-in such molten systems is disputed.In the present study,MF-AlF3(M=K,Cs)systems with molar ratios<1 were studied by in-situ Raman spectroscopy and molecular simulation.The results show that,in addition to AlF6^(3-),AlF5^(2-),and AlF4^-,the systems also contained Al2F-7^-.The characteristic bands in the Raman spectra belonging to Al2F-7^-were located at about 225 cm^-1,315 cm^-1,479 cm^-1,and 720 cm^-1.There are two possible structures of Al2F-7^-,which belong to the D3d and D3hpoint groups.Both of these structures are linear,and their single-point energies were found to differ by only 0.31 kcal/mol.展开更多
为提高稀疏信道估计性能,基于压缩感知(CS)理论,研究了正交频分复用(OFDM)系统中的导频设计问题。由于已有方法不能准确衡量采样矩阵重建性能,从而导致根据已有方法设计的导频具有较差的信道估计性能,因此提出以互相关矩阵元素的立方和...为提高稀疏信道估计性能,基于压缩感知(CS)理论,研究了正交频分复用(OFDM)系统中的导频设计问题。由于已有方法不能准确衡量采样矩阵重建性能,从而导致根据已有方法设计的导频具有较差的信道估计性能,因此提出以互相关矩阵元素的立方和为准则准确评价采样矩阵的重建性能。针对OFDM系统信道估计导频设计为离散组合优化问题,提出了一种并行完全树分组替换搜索算法用于搜索最优的导频。在算法的每次循环中,先将导频索引集合分组,再根据每一组替换的结果更新导频,提出的方法扩大了导频搜索空间,避免了导频搜索的局部最优问题。仿真结果表明,提出的评价方法相比现有方法能够准确评价采样矩阵重建性能,使用提出的准则设计的导频与现有互相关准则相比信道估计均方误差可减小约3 d B。同时,所提出的导频搜索算法具有更快的收敛速度和最优的导频搜索性能。展开更多
目的:考察乙醇-油酸聚乙二醇甘油酯(labrafil M 1944 CS)和聚氧乙烯氢化蓖麻油40(cremophor RH40)的鼻黏膜毒性,探讨其在鼻腔给药系统中应用的可行性。方法:以山梨糖醇酐油酸酯(span-80)和聚山梨酯-80(tween-80)为参比,采用在体蟾蜍上...目的:考察乙醇-油酸聚乙二醇甘油酯(labrafil M 1944 CS)和聚氧乙烯氢化蓖麻油40(cremophor RH40)的鼻黏膜毒性,探讨其在鼻腔给药系统中应用的可行性。方法:以山梨糖醇酐油酸酯(span-80)和聚山梨酯-80(tween-80)为参比,采用在体蟾蜍上腭模型,光学显微镜下观察纤毛持续运动时间,考察cremophor RH40和labrafil M 1944 CS的纤毛毒性作用;运用家兔血细胞溶血试验,考察cremophor RH40和labrafil M 1944 CS对细胞膜完整性的影响。结果:体积分数为1%时,4种表面活性剂对纤毛运动的影响顺序为cremophor RH40<labrafil M 1944 CS<tween-80<span-80;cremophor RH40的细胞膜毒性最小,tween-80和span-80次之,而labrafil M 1944 CS的影响最大;cremophor RH40对细胞膜完整性无影响用量为tween-80和span-80的15倍。结论:在一定体积分数下cremophor RH40的鼻黏膜毒性作用较小,可应用于鼻腔给药制剂的研制。展开更多
基金the National Natural Science Foundation of China(grant no.51474060)the National Key R&D Program of China(grant no.2017 YFC0805100)+1 种基金the National Natural Science Foundation of Liaoning Province(China)(grant no.2019-MS-129)the Fundamental Research Funds for the Central Universities of China(grant no.N162502002).
文摘The molten mixtures of alkali metal fluorides and aluminum fluoride are applied as aluminum electrolytes or brazing fluxes.However,the presence of Al2F-7^-in such molten systems is disputed.In the present study,MF-AlF3(M=K,Cs)systems with molar ratios<1 were studied by in-situ Raman spectroscopy and molecular simulation.The results show that,in addition to AlF6^(3-),AlF5^(2-),and AlF4^-,the systems also contained Al2F-7^-.The characteristic bands in the Raman spectra belonging to Al2F-7^-were located at about 225 cm^-1,315 cm^-1,479 cm^-1,and 720 cm^-1.There are two possible structures of Al2F-7^-,which belong to the D3d and D3hpoint groups.Both of these structures are linear,and their single-point energies were found to differ by only 0.31 kcal/mol.
文摘为提高稀疏信道估计性能,基于压缩感知(CS)理论,研究了正交频分复用(OFDM)系统中的导频设计问题。由于已有方法不能准确衡量采样矩阵重建性能,从而导致根据已有方法设计的导频具有较差的信道估计性能,因此提出以互相关矩阵元素的立方和为准则准确评价采样矩阵的重建性能。针对OFDM系统信道估计导频设计为离散组合优化问题,提出了一种并行完全树分组替换搜索算法用于搜索最优的导频。在算法的每次循环中,先将导频索引集合分组,再根据每一组替换的结果更新导频,提出的方法扩大了导频搜索空间,避免了导频搜索的局部最优问题。仿真结果表明,提出的评价方法相比现有方法能够准确评价采样矩阵重建性能,使用提出的准则设计的导频与现有互相关准则相比信道估计均方误差可减小约3 d B。同时,所提出的导频搜索算法具有更快的收敛速度和最优的导频搜索性能。
文摘目的:考察乙醇-油酸聚乙二醇甘油酯(labrafil M 1944 CS)和聚氧乙烯氢化蓖麻油40(cremophor RH40)的鼻黏膜毒性,探讨其在鼻腔给药系统中应用的可行性。方法:以山梨糖醇酐油酸酯(span-80)和聚山梨酯-80(tween-80)为参比,采用在体蟾蜍上腭模型,光学显微镜下观察纤毛持续运动时间,考察cremophor RH40和labrafil M 1944 CS的纤毛毒性作用;运用家兔血细胞溶血试验,考察cremophor RH40和labrafil M 1944 CS对细胞膜完整性的影响。结果:体积分数为1%时,4种表面活性剂对纤毛运动的影响顺序为cremophor RH40<labrafil M 1944 CS<tween-80<span-80;cremophor RH40的细胞膜毒性最小,tween-80和span-80次之,而labrafil M 1944 CS的影响最大;cremophor RH40对细胞膜完整性无影响用量为tween-80和span-80的15倍。结论:在一定体积分数下cremophor RH40的鼻黏膜毒性作用较小,可应用于鼻腔给药制剂的研制。
