Experimental and MD simulation of 3-dodecyloxypropanamine and 3-tetradecyloxypropylamine adsorbed onto quartz(101) surface

In this paper,two surfactants,3-dodecyloxypropanamine(DOPA) and 3-tetradecyloxypropylamine(TOPA),were synthesized and used as collectors in the quartz micro-flotation in the laboratory.Microflotation tests,FT-IR,XPS measurements,and ab initio Molecular Dynamics(MD) simulations were conducted to research DOPA,TOPA,and dodecylamine(DDA)'s adsorption mechanisms onto quartz(101)surfaces.The results of micro-flotation show that the adsorption of DOPA and TOPA onto quartz surface is more robust than that of DDA.The zeta-potential result shows that the DOPA/TOPA was adsorbed on quartz through electrostatic attraction.Then,MD simulation adsorption models were built to compare the computational properties of the three surfactants,such as the radial distribution function,and the interaction energies between the collectors and the quartz cleavage surface.The interaction energies of surfactants(RNH_(3)^(+) or RNH_(2)) on the quartz surface explained why the pH range of DOPA/TOPA is wider than that of DDA.XPS analyses and MD simulations confirmed that DOPA bonded with the(101) surface of quartz through three types of hydrogen bonds between the-NH_(2) of DOPA and the O atom of quartz.The hydrogen bonds of type A and type C were the most likely type and more potent than those of type B.

Dating Fault Activity Based on Surface Texture of Quartz Grains from the Bailong River Fault

Much important information referring to fault motion （e.g., fault activities period, intensity, frequency, and even dynamic background） can be revealed by resolving fault gouge, which is the result of fault motion while extruding or grinding. The field investigation encompassed sample collecting from the Bailong River fault system of the western segment of the Qinling Orogenic Belt （QOB）; 44 samples of fault gouges were collected for quartz micro-morphology analysis. These samples were analyzed using field emission scanning electron microscopy. In addition, 14 samples were tested for thermo-luminescence dating. The results showed that most of the surface textures of quartz grains are characterized by fish scale, moss-like texture, and stalactite. However, a small amount of orange peel-like fractures and worm-hole-like shaped surface texture were observed. Moreover, a few typical conchoids or subconchoidal fractures in quartz grains can be seen. This implies that the Bailong River Fault was active repeatedly during the Quaternary period, but the main motion period is the Pleistocene. The 14 thermo-luminescence dating values showed two age groups： 343.29-184.06 ka and 92.18-13.87 ka. These study data reveal that fault movement started during the Pliocene, occurred frequently in the early-middle period of the Pleistocene, and the peak frequency of the motion was reached in the early Pleistocene. The fault motions were stopped terminated in the early Holocene. The results are significant for the natural disaster risk evaluation in the western segment of the QOB.

Longitudinal leaky surface acoustic wave on Y-rotated cut quartz substrates

The properties of Quasi-longitudinal leaky surface acoustic wave(QLLSAW) on Y-rotated cut quartz substrates were presented. The phase velocity of QLLSAW on the quartz substrate along some orientations can be up from 6200 m/s to 7100 m/s, circa 100% above that of regular SAW. Both theoretical and experimental results show that QLLSAW propagating along some promising orientations for SAW devices are of small power flow angle and low tem-perature coefficient, for example, along the Euler angle (0°155.25°? 42°?, the measurements of phase velocity and temperature coefficient of delay of QLLSAW are 6201 m/s and 12.9 ppm/℃. The experimental results show that QLLSAW had little absorption by liquid loading on the substrate surface, which proved that the direction of particle motion is the same as wave vector and parallel to the surface of the substrates, i.e., the wave is of the properties of longitudinal wave.