The structure and properties of water and aqueous solutions have always been the focus of attention. The surface tension of acetone aqueous solutions were measured by using Raman spectra in different molecule environments, and the changes of surface tension were analyzed with hydrogen bonding in the mixtures. In this case, OH stretching bands were fitted into three Gaussian components and then assigned to different hydrogen-bonded structures. Furthermore, it can be concluded that the changes of microstructure on the binary mixture solutions exhibited regularly with the additive acetone, indicating that there showed the correlation between surface tension and relative peak intensity. The results show that the strengthening of hydrogen bonding between acetone and water will gradually weaken the surface tension of the solutions. It was confirmed that there showed the relationship between the microstructure and macroscopic properties of the aqueous solutions by the basis experiment data using a spectroscopy method.

Turbulent plane jets are prototypical free shear flows on which fundamental research can expand the overall understanding of turbulent flows. In this study, flow characteristics of the turbulent plane jets are studied by means of direct numerical simulation (DNS) based on the finite difference method. The effects of the initial conditions at the jet exit (i.e. Reynolds number and velocity profile) on the spatial development of velocity and scalar fields are mainly investigated. Meanwhile the instantaneous coherent structures, based on the-criterion and the local minimum of pressure, are presented. The results suggest that the plane jet flow with the higher Re (= ⁄ : is the bulk mean velocity at the jet exit, is the slot width, and ν is the kinematic viscosity) and the parabola velocity profile at the jet exit will correspond to the shorter potential core, furthermore, the lower Re and the parabola velocity profile will strengthen the decay of the mean field in the process of flow transition to full turbulence. The flow self-similarity will be achieved at shorter streamwise distance from the jet exit for the higher Re and the parabola velocity profile at the jet exit. Moreover, the dependency of coherent structures on the initial Reynolds number is remarkable, especially in the flow development region, but the change of initial velocity profile at the jet exit hardly acts on the scale of coherent structures. It is also observed that the scalar field is more sensitive to changes of initial conditions than the velocity field.

The effects of hydrogen bonds on the molecular structure of water-tetrahydrofuran (H2O–THF), water-dimethyl sulfoxide (H2O–DMSO), and water-tetrahydrofuran-dimethyl sulfoxide (H2O–THF–DMSO) in binary aqueous solutions and ternary aqueous solutions were studied using Raman spectroscopy. The results indicate that in the binary aqueous solution, the addition of THF and DMSO will generate hydrogen bonds with water molecules, resulting in changes in the peak positions of S=O bonds and C–O bonds. Compared with the binary aqueous solutions, the hydrogen bonds between DMSO and THF, and the hydrogen bonds between DMSO and H2O in the ternary aqueous solutions are competitive, and the hydrogen bond competition is susceptible to water content. In addition, the formation of hydrogen bonds will destroy the fully hydrogen-bonded water and make it change to the partially hydrogen-bonded water. By fitting the spectra into the three Gaussian components assigned to water molecules with different hydrogen bonding (HB) environments, these spectral features are interpreted by a mechanism that H2O in different solution systems has equal types of water molecules with similar HB degrees-fully hydrogen-bonded H2O (FHW) and partially hydrogen-bonded H2O (PHW). The ratio of the intensity transition from FHW to PHW is determined based on Gaussian fitting. Therefore, the variation of hydrogen bond competition can be supplemented by the intensity ratio of PHW/FHW ((IC2 + IC3)/IC1). This study provides an experimental basis for enriching the hydrogen bonding theory of multivariate aqueous solution systems.

Investigation of hydrogen bonding in neat dimethylsulfoxide and binary mixture (dimethyl sulfoxide + water) by concentration-dependent Raman study and ab initio calculation *Ouyang Shun-Li(欧阳顺利) a) , Wu Nan-Nan(吴楠楠) b) , Liu Jing-Yao(刘靖尧) b) , Sun Cheng-Lin(孙成林) a) † , Li Zuo-Wei(里佐威) a) ‡ , and Gao Shu-Qin(高淑琴) a)

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