ICP-AES法测定合金粉中的镍、铬、钴、铝和钇含量

采用ICP-AES法,直接测定合金粉中的Ni,Cr,Co,Al和稀土元素Y,优选了适宜的仪器测定参数和合适的分析谱线.研究了基体效应、共存元素间干扰及干扰校正方法,通过对实际样品的实验,测得Ni,Cr,Co,Al,Y检出限为10,10,8,10,3 μg·L-1;回收率96.5%,95.7,97.0%,97.9%,97.6%;RSD为1.06%,0.77%,0.70%,0.94%,0.50%.     

Observing capillarity in hydrophobic silica nanotubes

The development of template-synthesized silica nanotubes has created a unique opportunity for studying confined fluids by providing nanometer-scale containers in which the inner diameter (i.d.) and surface chemistry can be systematically and independently varied. An interesting question to be answered is the following: do solvents wet nanometer-scale tubes in the same way they wet ordinary capillaries? To answer this question, we have conducted studies to explore the wettability of the hydrophobic interiors of individual nanotubes. In these studies, single nanotubes with i.d.'s of either 30 or 170 nm were investigated over a range of water/methanol mixtures. These studies provide a direct route for comparing wetting phenomena in nanotubes with conventional macroscopic theories of capillarity. Our observations reveal four important aspects of capillary wetting in the 30-170 nm regime, a size range where the application of the Young-Laplace theory has not been experimentally investigated for hydrophobic pores. They are (i) a sharp transition between wetting and nonwetting conditions induced by addition of a cosolvent, (ii) invariance of this transition between nanotubes of 30 and 170 nm pore diameter, (iii) failure of the Young-Laplace equation to accurately predict the cosolvent's (methanol) mol fraction where the transition occurs, and (iv) reversibility of the observed wetting. The first two aspects conform to conventional capillarity (Young-Laplace), but the latter two do not. These measurements were complemented with ensemble experiments. The difference between theory and experiment is likely due to reliance on macroscopic values of contact angles or to liquid-phase instability within the hydrophobic pore.     

Sequential actions of palladium and cobalt nanoparticles immobilized on silica: one-pot synthesis of bicyclic enones by catalytic allylic alkylation and Pauson-Khand reaction

[reaction: see text] Palladium and cobalt nanoparticles immobilized on silica have been used as catalyst in a sequential allylic alkylation and Pauson-Khand reaction to form bicyclic enones.     

Anthracene derivatives bearing sulfur atoms or selenium atoms as fluorescent chemosensors for Cu and Hg: different selectivity induced from ligand immobilization onto anthracene

Two new selenium containing anthracene derivatives and two new sulfur containing anthracene derivatives were synthesized as fluorescent chemosensors for Hg²⁺ and Cu²⁺. Compound 1 displayed a highly selective chelation enhanced fluorescence quenching (CHEQ) effect only with Cu²⁺, on the other hand, compounds 3 and 4 displayed highly selective chelation enhanced fluorescence (CHEF) effects only with Hg²⁺ among the metal ions examined.