On coincidence problem in ELKO dark energy model

We study the critical points of a universe dominated by Eigenspinoren des Ladungskonjugationsoperatorsin (ELKO) spinor field dark energy and a barotropic matter without considering a specific potential or interaction. The coincidence problem and attractor solutions are discussed at late time, and it is shown that the coincidence problem can not be solved in this model.     

Experimental determination of the viscosity at the nanometer scale on a block copolymer with an oscillating nanotip

: This work is an attempt to investigate viscosities at the nanometer scale. To do so, the tapping mode atomic force microscopy is used on a triblock copolymer exhibiting a well-defined periodic structure at the nanometer scale. Variations of the oscillator amplitude and phase delay as a function of the tip-sample distance are recorded on the glassy and rubbery domains of the copolymer. The experimental data are compared to analytical expressions derived from Stokes law. In the present study, among the different possible expressions of the viscous forces depending on the tip shape and on the experimental length scale, only a force proportional to the indentation depth is able to describe the experimental data. In this particular case, quantitative measurements are possible. Finally, the oscillator is shown to be sensitive to local variations of the viscosity within few nanometers.     

Microextraction techniques for the determination of volatile and semivolatile organic compounds from plants: A review

Vegetables and fruits are necessary for human health, and traditional Chinese medicine that uses plant materials can cure diseases. Thus, understanding the composition of plant matrix has gained increased attention in recent years. Since plant matrix is very complex, the extraction, separation and quantitation of these chemicals are challenging.