陕西广电网络教育网解决方案

主要介绍了陕西广电网络教育网解决方案．对陕西广电提出的教育网网络结构和特点的作了简要说明。方案依托陕西广电网络的宽带传输网。通过对先进技术应用提出了高智能、支持多业务的教育网方案。     

Sequestering agents for uranyl chelation: new calixarene ligands

Synthesis of sulfocatecholamide (CAMS) and hydroxypyridinone (HOPO) calixarene ligands and determination of their binding abilities for the uranyl cation were described. Chelating properties were determined by UV spectrophotometry in aqueous media under various pH conditions and further studied by ¹H NMR analysis of the resonance signals of both aromatics' protons of the chelating groups. Each ligand shows a more or less pronounced affinity for uranium. HOPO calixarenes exhibit significant affinity towards uranyl ion at acidic and neutral pH while CAMS calixarene is more efficient at basic pH.     

Sequestering agent for uranyl chelation: new binaphtyl ligands

The synthesis of phosphonate, sulfocatecholamide (CAMS) and hydroxypyridinone (HOPO) binaphtyl ligands is presented. Their binding abilities for uranyl cation were determined by UV spectrophotometry in aqueous media versus pH. These titrations showed that the efficiency of these chelating agents depends on the nature of the chelating group. Each ligand shows a more or less pronounced affinity towards uranium. While the bisphosphonate compound did not show any affinity towards the uranyl ion, the BINHOPO derivative exhibits significant affinity at acidic and neutral pH while the BINCAMS is more efficient at basic pH.     

Sequestering agent for uranyl chelation: a new family of CAMS ligands

The synthesis of new dipodal bis-sulfocatecholamide uranophiles is presented. Their binding abilities for uranyl cation were determined by UV spectrophotometry in aqueous media under various pH conditions and further studied by ¹H NMR analysis of the resonance signal of both aromatic protons of the sulfocatecholamide groups. The results showed that the efficiency of these hydrosoluble chelating agents depends on the nature of the spacers. Each ligand shows a more or less pronounced affinity for uranium. The best receptor is the ligand CYCAMS 5d obtained as a mixture of cis/trans isomers, which achieves the best compromise between rigidity and steric hindrance.