^`H—NMR测定氰戊菊酯的立体结构与含量

本文运用核磁共振氢谱法并借助位移试剂Eu(fod)_3测定了氰戊菊酯四种旋光异构体的立体结构及其总含量,并对其R醇与S醇之比进行计算。同时,讨论了对上述结果的影响因素。     

Adsorption and stabilization of nano-TiO2 particles in a concentrated dispersion

The quantitative adsorption behavior of a hyperdispersant onto nano-TiO2 particles has been characterized by using FTIR(Fourier transform infrared) spectroscopy,NMR(nuclear magnetic resonance) and a negative adsorption method.The intrinsic adsorbed amount of hyperdispersant was(1.05±0.09) mg/m2.Thickness of the adsorbed layer was(4.66±0.42) nm.There was(74±7)% wt water in the adsorbed layer.In the hyperdispersant molecule,the anchoring group of the amide group attached frmly to the nano-TiO2 particles,and the solvatable chains of comb-type structure exhibited the effective steric stabilization.     

Au（PPh3）4ClO4的两种晶体与分子的结构

Au(PPh_3)_4ClO_4 的晶体有两种三方晶系构型,一种的空间群为R_3,a=b=c=1.186 3 nm,α=β=γ=73.82°;另一种的空群是 R3=b=c=898 6 nm,α=β=γ=44.13°该络合物分子本身具有三次轴的对称性,由于配体的空间位阻很大,因而它们与中心金原子的结合较松散,相互间的位置较不确定。     

Dispersion stability of thermal nanofluids

Thermal nanofluids, the engineered fluids with dispersed functional nanoparticles, have exhibited extraordinary thermophysical properties and added functionalities, and thus have enabled a broad range of important applications. The poor dispersion stability of thermal nanofluids, however, has been considered as a longexisting issue that limits their further development and practical application. This review overviews the recent efforts and progresses in improving the dispersion stability of thermal nanofluids such as mechanistic understanding of dispersion behavior of nanofluids, examples of both water-based and oil-based nanofluids, strategies to stabilize nanofluids, and characterization techniques for dispersion behavior of nanofluids. Finally, on-going research needs, and possible solutions to research challenges and future research directions in exploring stably dispersed thermal nanofluids are discussed.