The longitudinal development and other characteristics of the EECR induced atmospheric showers can be studied from space by detecting the fluorescence light induced in the atmospheric nitrogen. ...According to the Airwatch concept a single fast detector can be used for measuring both intensity and time development of the streak of fluorescence light produced by the atmospheric shower induced by an EECR. In the present communication the detection capabilities for the EECR observation from space are discussed.
Schemes for profiling the ends of VT6 alloy billets prior to their subsequent rolling on radial-displacement rolling mini-mills were examined in order to minimize the shrinkage cavity defect and ...increase the product yield. During both physical and computational profiling experiments, rollers of various shapes were used in combination with the local heating of profiled ends. The profiling time was determined in physical and computational experiments. The roller pressure was estimated based on the results of computer simulation in the QForm computing environment. For a billet with a diameter of 27 mm, the shortest profiling time was obtained using two V‑rollers with the smallest roller pressure of 0.81 kN, which is 1.7–1.9 times less as compared to other studied patterns. Therefore, it is rational to select a V-shaped profiling roller with taper angles, ensuring the absence of a shrinkage cavity during the subsequent bar rolling.
Purpose. Geometric synthesis of a statically determined spatial eight-link hinged mechanism with rotary kinematic pairs of a barreling machine, in which the working capacity carries out a complex ...spatial movement, followed by an analytical study of the structural features of the machine mechanism. Methodology. An analytical approach was used in the study of the eight-link hinged mechanism with rotary kinematic pairs, which consists of geometric and structural synthesis, and the design of barreling machine was modeled in the SolidWorks 2021 automated design software. Findings. One of the possible options for freeing the spatial mechanism of the barreling machine from passive connection is proposed, the synthesis of a statically determined spatial eight-link hinged mechanism with rotational kinematics is carried out. An appropriate design of a barreling machine with two driving links has been developed, the use of which creates conditions for increasing its reliability during operation and simultaneously increasing the productivity of performing the corresponding barreling operations. Analytical studies of the main geometric and structural parameters of the barreling machine were carried out. Originality. The connection between the corresponding geometric parameters of the synthesized statically determined spatial eight-link mechanism is established, which allows determining the rational ratio of the lengths of its links to each other. The relationship between the lengths of the links, their position and the angle of swing of the rocker arm together with the drive shaft of the machine is also established. Practical value. The synthesis of a statically determined spatial eight-link hinged mechanism with rotary kinematic pairs with two degrees of mobility was performed. Based on the synthesis of the mechanism, a new design of the barreling machine with two driving links was developed. Mathematical expressions for calculating the main geometric relationships of the link lengths of the developed machine structure were obtained.
Hot pressing was used to produce compact ceramic samples with the following composition (wt.%): 60 ZrB
2
+ 20 SiC + 20 (Al
2
O
3
+ 32 t-ZrO
2
). The tetragonal modification of zirconium oxide in the ...eutectic was stabilized by yttrium oxide. The porosity of the samples was 3–5%. The mechanical properties of the ceramics (hardness
HV
, fracture toughness
K
Ic
, tensile strength
δ
f
, compressive strength
Y
, grain-boundary strength
S
, and bending strength σ) were studied. Analysis of the microstructure and elemental composition of the phases revealed that a defect-free structure developed in the ZrB
2
-based composite through strong Van Der Waals adhesive interaction at the SiC–Al
2
O
3
interface, which increased the fracture toughness to 9.4 MPa ∙ m
1/2
. In turn, this increased the grain strength from 0.64 GPa for the basic composite to 3.46 GPa for the ZrB
2
–SiC composite with an oxide addition. An addition of Al
2
O
3
+ 32 wt.% t-ZrO
2
was introduced in sufficient quantities not only to reduce the fracture stress but also to promote plastic deformation of the material for high-temperature bending strength. Study of the oxidation process showed that the weight increment of the 60 wt.% ZrB
2
+ 20 wt.% SiC + 20 wt.% (Al
2
O
3
+ 32 wt.% t-ZrO
2
) sample at 1600°C for a holding time of 1 h was stabilized by dense oxide scale formed on the material, while the weight increment of the ZrB
2
+ 20 wt.% SiC sample and, consequently, the scale thickness increased monotonically. The scale that formed on the ZrB
2
+ 20 wt.% SiC samples with an addition of Al
2
O
3
+ 32 wt.% t-ZrO
2
consisted of an upper Al
2
SiO
5
-based layer 50 μm thick with ZrO
2
inclusions and a lower ZrO
2
-based layer up to 80 μm thick with Al
2
SiO
5
inclusions. The eutectic Al
2
O
3
+ 32 wt.% t-ZrO
2
oxide addition to the basic ZrB
2
–SiC system had higher oxidation resistance and thus prevented the diffusion of oxygen into the material.
Methods for the preparation of raw materials to produce leucosapphire are considered. It is shown that the main directions in the production of high-purity aluminum oxide raw materials are: ...electrochemical oxidation of aluminum, decomposition of alkoxides, high-temperature treatment of aluminum oxide in a halogen-containing atmosphere, and preliminary purification of aluminum-containing compounds followed by their decomposition. It is shown that methods of the purification of aluminum hydroxide and oxide obtained by the Bayer process are the most promising for industrial use. These methods include the complex purification and simultaneous preparation of ceramic preforms starting from aluminum hydroxides or oxides by their treatment in subcritical or supercritical steam and the following heat treatment in a halogen-containing medium.
Studies conducted as part of the Federal target program “Research and Development in Priority Directions for the Development of the Russian Science and Technology Complex for 2014–2020”, showed high ...efficiency of interaction of calculated norms of mineral fertilizers with modern bioagents RECB-50B, RECB-95B and adaptogenic drugs. At the same time, the actual yield of spring rapeseed of the Gedemin variety exceeds the planned one (3 t/ha) by 9.3–12.3 %, respectively, the chemical load on the environment is reduced and the cost of production of oilseeds is reduced.
The conversion of gibbsite to boehmite via hydrothermal treatment at 200°С in 1.5 wt % HCl is studied by X-ray powder diffraction, IR spectroscopy, Brunauer–Emmett–Teller analysis, scanning (SEM) and ...transmission (TEM) electron microscopy. The steps of the process are identified. Gibbsite is split in an acidic medium, with its specific surface area increasing up to 150 m
2
/g, into thin lamellas that have a disordered boehmite structure. Needle-shaped boehmite crystals are formed from thin elongated lamellas of diverse sizes due to the oriented overlaying and cross-linking with the elimination of weakly bound water and structural perfection.
Abstract
Today’s the problem of food security is the object of close attention of the world scientific community and international organizations. Food is the most important material basis for the ...existence of mankind and a necessary condition for the development of human civilization as a whole. Food safety is the part of the country’s national security; it ensures the life of the entire society and determines the economic, political and social independence of the state. In recent years, there has been a sharp deterioration in the quality of food around the world, which is primarily due to the chemization of agriculture in order to increase production and solve the problem of food shortages. The use of pesticides to control weeds, diseases and pests increases yields, but these substances accumulate in the soil, and through it in crops. However, as a result, pesticides are directly or indirectly introduced into agricultural products and from them into food products. Pesticides are xenobiotics that are foreign to living organisms and are not part of the natural biotic cycle. The consumption of pesticides with food harms human health. Pesticides also play a negative role in the technological processes of food production using microorganisms, for example, in wine-making, pesticides worsen the fermentation activity and the physiological state of yeast. The article presents the results of research on the effect of organochlorine pesticides on biochemical transformations in the process of obtaining apple wine materials.
A new method for producing a nanosized γ-Al
2
O
3
powder was proposed, by which a saturated solution of aluminum oxychloride and sucrose was subjected to sequential heat treatment to 350°C to form a ...transient species and then to 800°C to form a nanosized γ-Al
2
O
3
powder. The optimal treatment parameters were determined. Stages of the process were identified. The transient species and the nanosized γ-Al
2
O
3
powder were studied.
Over the last 10 years new types of polymeric materials with molecular recognition sites for low-weight organic substances have been prepared using the molecular imprinting approach. In this review ...paper, in particular, the recognition and transport properties of molecularly imprinted polymer (MIP) membranes prepared thus far are summarized and analyzed. Microporous and macroporous MIP membranes show the same receptor but largely different transport properties. The nature of selectivity of microporous MIP membranes is discussed and a descriptive model for transport selectivity via specific “gates” is developed. The high specificity and stability of MIPs render them as promising alternatives to enzymes, antibodies, and other natural receptors usually used in affinity chromatography and sensor technology. The application potential of MIP membranes, especially for affinity separations, membrane chromatography and membrane sensors, is outlined. Conclusions about the possibilities to improve their performance are presented. In general, these investigations open a way to the design of supramolecular devices that could perform highly selective functions such as recognition, transformation, transfer, regulation and allow signal and information processing.
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