Gun and Fire Lighter Flints, Gun Supplies from the “Russian” Cultural Layers of the Fortress of Azov of the 17th–18th Centuries

During the 17th–18th centuries, the fortress of Azov played an extremely important role in the geopolitics of the Russian state and the Ottoman Empire. During the period of the “Azov sitting” (1637–1642) Azov was the base of the Don Cossacks, and under Peter I (1696–1711) it provided Russia with control over the Azov basin and gave access to the Black Sea. Under the terms of the Treaty of the Pruth, in 1711 Azov returned to the power of Turkey. In 1736 it was recaptured by Russian troops. Azov finally passed to Russia in 1774 under the Treaty of Kuchuk-Kainarji, and in 1775–1782 it was the center of the Azov province. Cultural layers of Azov of 17th––18th– centuries considerably damaged as a result of repeated destruction of a fortress and its subsequent reconstruction. Among the findings, a relatively small series of gunflints, parts of tinderbox and lead bullets are revealed by the authors

Gunflints and Fire-Steel Flints from the Fortress of Liutic (XVII–XVIII centuries) on the Lower Don Region

Nowadays the archaeology of Modern times actively develops. Gunflints and fire-steel flints take an important place in a complex of the material remains of the 17–18th centuries. The considerable collection of such products (259 pieces) comes from the fortress of Lutik (Sed-Islam, in Osman tradition) in the lower reaches of Don. The fortress existed from 1660 to 1741. The occupation layer contains both “Turkish” and “Russian” archaeological remains, and it is difficult to separate them from each other. The publication contains the quantitative and qualitative characteristics of this specific category of archaeological findings. Materials are described in terms of the Stone Age archaeology. For understanding of specifics of a flint complex, a gunlock, lead bullets and iron fire-steels are also described in the publication

Selfie in student environment: from selfie addiction awareness to everyday practices study

The relevance of this article is to study such a social phenomenon as selfie. With the development of society, the life of each person changes, the practices of his/her behavior change, as well as new ones arise under the influence of emerging social phenomena. The article considers the views of students about selfies; it defines types of selfies in different categories. It is revealed that preference is given to individual selfies, on holidays or events that are important for the author personally, in order to capture their emotions. It is revealed that almost half of students have a low degree of activity in accounts and is expressed in monitoring the publications of other users.La relevancia de este artículo es estudiar un fenómeno social como la selfie. Con el desarrollo de la sociedad, lavida de cada persona cambia, las prácticas de su comportamiento cambian, así como otras nuevas surgen bajo la influencia de fenómenos sociales emergentes. El artículo considera las opiniones de los estudiantes sobre selfies; define tipos de selfies en diferentes categorías. Se revela que se da preferencia a selfies individuales, en días festivos o eventos que son importantes para el autor personalmente, con el fin de capturar sus emociones. Se revela que casi la mitad de los estudiantes tienen un bajo grado de actividad en las cuentas y se expresa en el monitoreo de las publicaciones de otros usuarios

Titanium Oxide Microspheres with Tunable Size and Phase Composition

Due to their unique physical and chemical properties, monodisperse titanium oxide microspheres can be used in dye-sensitized solar cells, as cosmetic pigments, and for other applications. However, the synthesis of microspheres with narrow size distribution, desired phase composition, and porosity is still a challenge. In this work, spherical titania particles with controllable size, crystallinity, and pore size were obtained by Ti(OnBu)4 hydrolysis in ethanol. The influence of NaOH addition on the particles’ size and morphology was investigated for the first time. Particle diameter can be tailored from 300 nm to 1.5 μm by changing water and NaOH concentrations. Particle size was analyzed by the statistical processing of scanning electron microscopy (SEM) images and differential centrifugal sedimentation (DCS) measurements. Optical properties of the microspheres were studied by diffuse reflectance UV-Vis spectroscopy. Thermal and hydrothermal treatment allowed transforming amorphous phase in as-prepared particles into nanocrystalline anatase and/or rutile. Transmission electron microscopy (TEM) study of the lamellae, cut out from spherical particles using focused ion beam (FIB), revealed that as-synthesized microspheres are non-hollow, homogeneous, and crystallize throughout the whole volume of the particle. The spherical particles possess photoprotective properties; the highest sun protection factor (SPF) was observed for amorphous microspheres

Investigation of catalytic hydrogen sensors with platinum group catalysts

Environmental deterioration and limited resources of hydrocarbons push the development of alternative power sources. One of the most promising energy carriers is hydrogen. However, handling hydrogen is more hazardous than the use of hydrocarbons because it has a significantly wider flammable range. Thus the development of new sensors for preventing hydrogen leakage is the actual task of modern materials science and chemical engineering. In this work, the response of catalytic sensors to hydrogen with different catalysts of platinum group (Pt, Pd, Ir, Rh, Pt+Pd, Pt+Pd+Rh, Pt+Pd+Ir) in the pre-explosion concentration range is studied. Temperature dependencies of sensitivity are discussed. A hysteresis in sensor response is observed during the cycling of the supply voltage. This phenomenon can be explained by partial transformation of platinum group metal oxides into metallic phase at a temperature of more than 500 C and reverse metal oxidation at temperatures less than 400 C. It has been shown that the sensors with catalysts containing Ir and Rh demonstrate more preferable characteristics for practical applications. 

“Hydrotriphylites” Li1-xFe1+x(PO4)1-y(OH)4y as Cathode Materials for Li-ion Batteries

Lithium iron phosphate LiFePO4 triphylite is now one of the core positive electrode (cathode) materials enabling the Li-ion battery technology for stationary energy storage applications, which are important for broad implementation of the renewable energy sources. Despite the apparent simplicity of its crystal structure and chemical composition, LiFePO4 is prone to off-stoichiometry and demonstrates rich defect chemistry owing to variations in the cation content and iron oxidation state, and to the redistribution of the cations and vacancies over two crystallographically distinct octahedral sites. The importance of the defects stems from their impact on the electrochemical performance, particularly on limiting the capacity and rate capability through blocking the Li ion diffusion along the channels of the olivine-type LiFePO4 structure. Up to now the polyanionic (i.e. phosphate) sublattice has been considered idle on this playground. Here, we demonstrate that under hydrothermal conditions up to 16% of the phosphate groups can be replaced with hydroxyl groups yielding the Li1-xFe1+x(PO4)1-y(OH)4y solid solutions, which we term “hydrotriphylites”. This substitution has tremendous effect on the chemical composition and crystal structure of the lithium iron phosphate causing abundant population of the Li-ion diffusion channels with the iron cations and off-center Li displacements due to their tighter bonding to oxygens. These perturbations trigger the formation of an acentric structure and increase the activation barriers for the Li-ion diffusion. The “hydrotriphylite”-type substitution also affects the magnetic properties by progressively lowering the Néel temperature. The off-stoichiometry caused by this substitution critically depends on the overall concentration of the precursors and reducing agent in the hydrothermal solutions, placing it among the most important parameters to control the chemical composition and defect concentration of the LiFePO4-based cathodes