-We present the results of the structural analysis of inverse opal photonic crystals by microradian X-ray diffraction. Inverse opals based on different oxide materials (TiO2, SiO2 and Fe2O3) were fabricated by templating polystyrene colloidal crystal films grown by the vertical deposition technique. Our results suggest that most inverse opal films possess dominating twinned face-centered cubic structure accompanied by some fragments of hexagonal close-packed and random hexagonal close-packed structures. The studied samples possessed individual structures with different ratios of the above fragments. By fitting the results of the angular-dependent X-ray diffraction by the Wilson model we estimate the stacking probability α in the studied samples to be ∼0.7-0.8. Microradian X-ray diffraction therefore provides detailed structural information on opal-based photonic crystals and can be applied to opaque inverse opals or the samples with a periodicity < 300 nm, whose structure cannot be investigated by conventional optical methods.
Here we report the synthesis and investigation of iron and iron oxide nanowire arrays using mesoporous silica as a host material. In the present work a novel variant of synthesis of ordered magnetic nanowires in the mesoporous silica matrix was suggested. The method is based on the incorporation of a hydrophobic metal compound into the hydrophobic part of silica-surfactant composite. The amount of iron intercalated into the mesoporous matrix was measured by chemical analysis. In all samples it corresponds well to with the molar ratio SiO2: Fe = 9:1. To provide crystallinity of nanowires additional thermal treatment was performed. Thus prepared nanocomposites were characterized by TEM, ED, SAXS, SANS, BET and magnetic measurements. The anisotropy parameters of nanowires were determined using two non-correlated methods: temperature dependence of magnetic susceptibility and small angle polarized neutron scattering. It was found that the particle length increases with the increasing of the decomposition temperature of the metal complex. Obviously it deals with crystallization and growth of metal particles inside the pores at a constant diameter of a single particle. For iron containing sample annealed at 375 °C (form factor of nanowire is about 40), the coercive force at room temperature was found to be 145 Oe at saturation magnetization of 1.2 emu/g, which is not far from modern information storage. It was shown that particles shape and size are in good agreement with that of the pores. Particles are uniform and well ordered in the silica matrix. Thus, the suggested method leads to one-dimensional anisotropic nanostructures which could find an application as high-density data storage magnetic media.
The present article explores the possibilities of restoring the tourism industry in the Russian Federation by attracting investment and public-private partnership. The purpose of the study is to analyze the possibilities of restoring the Russian tourism industry, taking into account the losses incurred due to the COVID-19 pandemic, and to determine the main areas of state support. The article provides an analysis of statistical information showing the calculated amount of damage to the tourism industry from the spread of coronavirus infection, and possible negative consequences in the future, as well as data from an expert sociological survey. The authors analyze the measures and the need for state support for the industry that is in an ongoing state of economic crisis and note the problems of tourism development in Russia and several European countries that resulted from the spread of coronavirus infection. The authors consider possibilities and prospects of restoring the tourism industry in the future, describe measures to support the tourism industry planned by the Russian government, as well as anti-crisis programs undertaken in several European countries that are designed to help the tourism industry survive during the crisis. It is shown that support measures undertaken in Russia are incomparable with the help provided to the tourism industry by the governments of several European countries. The authors question the effectiveness of these measures as well as consider possible changes in the business model of the tourism industry and the opportunities to increase the role of public-private partnership projects. The results and suggestions proposed by the authors will be of interest to both the tourism business practitioners, investors in the tourism industry, representatives of relevant government agencies, and researchers studying issues of state regulation of the tourist services market.
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