North-Caucasus Federal University

Background. Various methods are widely used in diagnosing the technical condition of automotive engines, but most require highly skilled personnel and sophisticated equipment. Vacuum diagnostics, based on measuring the vacuum in the intake manifold, is an accessible and effective way to assess the condition of the engine and auxiliary systems. Purpose. To explore the potential of using a mechanical vacuum gauge to diagnose the technical condition of the cylinder-piston group, valve timing systems, valves, and other engine components of various designs. Materials and methods. A mechanical pointer vacuum gauge was used in this study to measure the vacuum at various points in the vacuum systems of gasoline and diesel engines. The dynamics of the instrument readings were analyzed, faults were modeled, and a comparative analysis was conducted with compression diagnostics, computer diagnostics, and oscillographic methods. Results. The method demonstrated high information yield for identifying air leaks, valve malfunctions, valve timing issues, ignition problems, and other faults. Practical recommendations for interpreting vacuum gauge readings and a table of reference vacuum values for various engine types are provided.

The cheese industry yields a lot of whey as byproduct. Whey contains dispersed phase components with modified native properties, which means it can be used in functional food formulations. Despite being a popular industrial process, membrane separation of whey lacks reliable information on the fractionation processes. This article introduces a new milk processing technology based on microfiltration separation of carbohydrate-mineral fraction (native whey) from skim milk during soft cheese production. The retentate with high micellar casein content made the cheese mix more efficient, as determined by the rennet-fermentation test of the original grade three milk. Compared to the conventional technology (State Standard GOST R 53437-2009), the new approach made it possible to recover up to 40% of permeate with a high-molecular polydisperse phase in its native form, thereby reducing the whey yield already at the first stage. The casein content in the soft cheese mix could be varied by adding different shares of microfiltration retentate. The finished cheese product had the sensory profile of commercial cheese.

The paper studies an episode of the Afghanistan survey performed by the officers of the Caucasus corpus’ Headquarters. The backcloth of the research is the history of the diplomatic Afghan ambassy that arrived in the Caucasus in 1835. The primary sources are kept in Russian central archives and museums such as RSMHA, SISM RSL, SM RNL, and DM SHM. The purpose of the study was to analyze the problem of the formation of ideas about the so-called “imperial geography” of frontier territories that developed in Russia as well as in other European countries in the 19th century. The article analyzes the contents of two secret notes compiled by officers of the General Staff according to the canons of military-statistical descriptions of territories as well as materials from the investigation conducted into the identities of the Afghan ambassadors. We use the “post-colonial criticism” approach widely practiced by the foreign researchers, primarily the concept of E. Said’s Orientalism conception and also methodology of the Malay historian Farish A. Noor focused on the Europeans data-gathering in the East regions. The author also took into account a systematic approach to the study of international relations, which allows considering the analytical work of the officers of the Separate Caucasian Corps in the context of the influence of the information they collected on the development of the course of diplomatic relations between the Russian Empire and the countries of its South-Eastern borderland. The paper headlines that, despite the adventurism of the embassy, the Headquarters was able to derive maximum benefit from the fact that people from Afghanistan arrived in the region. The actions of the commanding stuff indicate that it understood the connection between power, the need to expand the borders of the empire and the need to study the near, as well as remote Caucasus vicinity. The article is addressed to a wide range of researchers and all those who are interested in Russian intellectual acquisition of the East, as well as the history of the 19th century diplomacy.

This study addresses the challenge of enhancing the structural secrecy of information transmission systems employing code-division multiplexing. To increase the structural secrecy of information transmission systems with coded channel separation, the necessity of increasing the number of used ensembles of orthogonal code sequences is proved. One of the possible ways to expand the number of orthogonal code sequences is the use of eigenvectors of Hermitian matrixes. Due to the complex component, multiphase orthogonal code sequences are obtained, the expansion of the number of which can be achieved by changing both the modules and arguments of the Hermitian matrix coefficients. However, not all multiphase orthogonal code sequences obtained from the eigenvectors of the Hermitian matrix will have the established requirements for correlation characteristics. The objectives of the paper are to determine the constraints for 4-th order Hermitian matrices at which ensembles of orthogonal multiphase code sequences described by their eigenvectors satisfy the first and second "condition of L. E. Varakin" by their correlation functions. The possible values of side peaks of correlation functions for different values of arguments of Hermitian matrix coefficients are calculated. Establishment of the ranges of changes in the side peaks of autocorrelation DRj and cross-correlation DRjk functions of ensembles of orthogonal multiphase code sequences have been established, which respectively lie within the limits from Rjmin = 0.25 to Rjmax = 0.75 and from Rjkmin = 0.5 to Rjkmax = 0.75.

The emergence of Internet of Things (IoT) panned a lot of wearables that has a broad scope of applications, especially in health, fitness and personal monitoring. However, traditional electronics have been made of hard materials which have strong limitations on sensations of feeling, flexibility, durability whereas all of those are required for wearable devices. With the de velopment of IoTdriven wearables, flexible and stretchable material integration into the device could be a new opportunity to break through these obstacles. These advanced materials, which include conductive polymers, graphene, and elastomers, can be used to fabricate wearable electronics for curving, stretching and matching the human body. In this chapter, we review the use of such materials for designing and developing the ubiquitous wearable IoT devices described above by discussing their characteristics, benefits, and processing methods. Issues such as flexible electronics integration, sensor accuracy, power management, and long-term durability are also addressed.

Yttrium–aluminum garnet (YAG) ceramics doped with ruthenium atoms were synthesized in this study. The precursor powder was obtained by the coprecipitation method. The dopant, in the form of ruthenium (III) chloride, was introduced at different technological stages: during precursor powder synthesis and during deagglomeration of the ceramic powder, resulting in two series of samples. The phase composition of the sintered ceramics was examined by X -ray diffraction (XRD). According to the obtained data, no secondary or impurity phases were detected. Differential thermal analysis (DTA) revealed a decrease in the cationic homogeneity of the precursor powder. Incorporation of ruthenium into the YAG structure led to a shift of the exothermic crystallization peak toward higher temperatures. The ceramic samples were sintered at 1815 °C for 20 h, followed by annealing in air at 1500 °C for 2 h. Optical characterization of the ceramics showed that the method of dopant introduction affected both the optical transmittance and the band gap energy. The transmittance at 1100 nm for undoped YAG ceramics was 77.04 %, while for the ruthenium-containing samples it decreased to 65.1 and 74.5 %, depending on the dopant incorporation route. The band gap energy was determined from differential absorption spectra: for pure YAG it was 4.92 eV, and for the Ru-doped ceramics it decreased to a minimum of 4.4 eV.

We report an efficient base-catalyzed cyclization ofreadily available ortho-nitroalkylaminoquinolinesfor the synthesis of a seriesof imidazo­[4,5-f]­quinoline and imidazo­[4,5-h]­quinoline N-oxides. Using alkali metalalkoxides in anhydrous alcohol, we achieved good to excellent yields(up to 92%) of various N-oxides, allowing the corresponding N-oxidation products to be obtained selectively. The methodis suitable for a wide range of substituents (except tertiary amines).This protocol opens a direct route to new, previously inaccessibleimidazo­[4,5]­quinoline N-oxide derivatives, openingthe way for future pharmacological studies, given their purine-likestructures and potential therapeutic applications.