Measurement of high frequency ultrasound in liquids using high-resolution Bragg reflection technique

A new light scattering technique has been established for simultaneous measurement of ultrasonic velocity and absorption in liquids over a frequency range from 100 to 1000 MHz. The technique is applied to studies of vibrational relaxation in the uhf range, and the velocity-dispersion and absorption curves in several organic liquids are presented.     

Selective synthesis of epolactaene featuring efficient construction of methyl (Z)-2-iodo-2-butenoate and (2R,3S,4S)-2-trimethylsilyl-2,3-epoxy-4-methyl- gamma-butyrolactone

[reaction: see text] (+)-Epolactaene was synthesized in 14 steps in the longest linear sequence. The synthesis is highlighted by a highly efficient preparation of the lactone intermediate 4, which only requires three steps from the commercially available (S)-3-butyn-2-ol. It also features a fully stereocontrolled synthesis of the intermediate 9, which was constructed through the use of Zr-catalyzed methylalumination of alkynes and a series of Pd-catalyzed organozinc cross-coupling reactions, such as homopropargylation, direct ethynylation, and alkenylation of the methyl ester of (Z)-alpha-iodocrotonic acid (3).     

EXAFS and XANES Studies on 3d Transition Metal Intercalation Compounds M x TiS2

Abstract

EXAFS and XANES spectra of Ti K-edge have been measured for 3d transition metal intercalation compounds M _x TiS₂ (M = Mn, Fe, Co and Ni; x ≤ 0.33). We have found that the interatomic distance between Ti and the first nearest neighbor S atoms, R(Ti-S), increases with the guest concentration x. The variation in XANES spectra with x reveals the reduction of the valence state of Ti atoms upon intercalation of M. From these results as well as the M K-edge EXAFS data studied previously, we have proposed a simple model on the local structure of M _x TiS₂ to reproduce the observed values of R(Ti-S) by averaging local shift of S atoms caused by intercalation.     

Preparation of the TiO2 Thin Film Photocatalyst by the Dip-Coating Process

Titanium dioxide (TiO2) coated glass-plate thin film photocatalysts for elimination of air pollutants, were prepared by the dip-coating process with titanium alkoxide including polyethylene glycol (PEG). The surface structure of these thin films changed drastically with the size of the PEG. They were either transparent or opaque. Nitrogen oxides (NOx), one of the most hazardous of air pollutants, were found to be efficiently eliminated by the thin film photocatalyst. The photocatalytic activities of the transparent and opaque thin films were found to be almost equal. This may be due to the two films having the same surface area. The highest activity was obtained for thin films around 1 m.     

How does the mobility of phospholipid molecules at a water/oil interface reflect the viscosity of the surrounding oil?

The mobility of phospholipid molecules at a water/oil interface on cell-sized phospholipid-coated microdroplets was investigated through the measurement of diffusion constants by fluorescence recovery after photobleaching. It is found that the diffusion constant of phospholipids showed the relation D approximately (eta water + eta oil) -0.85, where D is the diffusion constant, eta water is the viscosity of water, and eta oil is the viscosity of oil. This observation indicates that the viscosity of the surrounding oil is the primary factor that determines the diffusibility of phospholipids at a water/oil interface.     

Synthesis of dendritic oligothiophenes and their self-association properties by intermolecular pi-pi interactions

[structure: see text] The addition of oligothiophene into a dendritic structure causes a self-association behavior by intermolecular pi-pi interactions in a solution and in a solid state. Increasing the generation of the dendritic structure gives not only a high association constant but also sufficient field-effect hole mobility, which indicates that the charge-transporting passes are formed by the strong pi-pi interactions.