The creation of hydrophobic anti-icing and self–cleaning coatings is a relevant task for many industrial sectors. The potential field of application includes production of liquid and gas separators and filters, the field of textiles and clothing, construction and new materials, optical and microelectronic devices, the field of automobile construction and maritime shipping as well as energy and agriculture. The article suggests a new approach to the creation of superhydrophobic anti-icing coatings, by drawing peeled multi-walled carbon nanotubes (MWCNTs) to the sample surface. This method allows you to combine the necessary factors: Low surface energy, micro-nano-roughness and hierarchical multi-scale. The authors investigated the dependence of the wetting angle of such a surface on the model of MWCNT, fractional composition and the polarity of the dissolvent. The suggested approach can be used to create superhydrophobic coatings with the additional function of removing static charge and heating the surface, which can be used in the field of energetics for protection against freezing of wind turbine blades and aircraft surfaces.
The influence of sandblasting on surface and subsurface of stainless steel is investigated using variable energy positron beam (VEP), positron annihilation spectroscopy (PAS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Samples of stainless steel were blasted using 110 μm particles of Al2O3 under different pressure and time duration. In the case of sandblasting for 90 s, the reduction of positron diffusion length depending on the applied pressure was observed. Sandblasting during 30 s leads only to the reduction of positron diffusion length to about 60 nm for all samples. Positron lifetimes close to 170 ps measured using positrons emitted directly from the source point to the presence of vacancies on the dislocation lines. SEM and AFM images show that surface roughness depends rather on pressure of sandblasting than time of exposition.
The scattering of ultra-short X-ray pulses (USPs) is an important component of diffraction analysis of matter. Usually, the specific scattering of such USPs is not taken into account to determine the structure of a substance. Taking into account the specifics of scattering on complex structures will give more accurate results when deciphering complex structures. In this work, it is shown that when X-ray USPs are scattered on diamond with NV centers, it is necessary to take into account the pulse duration. The results obtained can be very different from the widely used theory of diffraction analysis, which confirms the need to take into account the specifics of USP scattering when diagnosing complex structures. It is shown that the scattering spectra are very sensitive to the concentration of NV-centres in the diamond structure, and this can be used in diffraction analysis.
Currently, the study of the scattering of ultrashort X-ray pulses (USPs) by various objects is an urgent task, in connection with the creation of powerful sources of USP generation. In this paper, the theory of the scattering of attosecond pulses by polyatomic structures is developed taking into account the magnetic component of USPs. It is shown that the scattering spectra depend not only on the structure of the target, but also on other characteristics of USPs. Results are presented of the calculation of the scattering spectra on various nanosystems, such as rings, groups of rings, carbon nanotubes (CNTs), and groups of co-directed CNTs (forest CNTs). The calculation results are presented in an analytical form, which allows a general analysis of the expressions. It was found that taking the magnetic component of the momentum into the scattering spectra into account leads to the generation of the second harmonic. In this case, the spectra have characteristic features and differ from the scattering spectra at the carrier frequency, which can complement ultra-high-resolution X-ray analysis. It is shown that the scattering spectra of some structures, for example, forest CNTs, have a strictly specified radiation direction and such material in the field of such USPs is non-reflective (completely black).
At present time the Low Energy Positron Toroidal Accumulator (LEPTA) at JINR is under commissioning with circulating positron beam. The LEPTA facility is a small positron storage ring equipped with the electron cooling system and positron injector. The maximum positron energy is of 10 keV. The storage ring is aimed for generation of direct fluxes of ortho-positronium (o-Ps), produced in recombination of the positron beam circulating in the ring with single pass cooling electron beam. The project has few goals: annihilation spectroscopy (PAS) to monitoring defects of nanometer sizes in materials as a function of depth managed by the positron energy in a rage of a few eV to 100 keV.
We calculate the reradiation spectra of ultrashort pulses of an electromagnetic field on single- and double-centered negative ions in the zero radius potential approximation. We show that the cross se