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Heat exchangers are important components of cryogenic installations. The modern and advanced cryogenic systems have bulky heat exchangers, weigh tens of tons, are made of copper and its alloys, stainless steel or aluminum. The main challenge in the field is related to the need to reduce size and weight of the heat exchangers by using appropriate construction shape and modern materials. Heat exchangers used in cryogenics can be divided into three main groups: tubular, spiral and efficient or compact exchangers. In ...

It is shown that the corrosion-electrochemical behavior of coatings with iron (cobalt) tungsten alloys depends on the content of the refractory component, and the increase in chemical resistance in an acidic medium is due to the formation of acidic tungsten oxides on the surface. The use of artificial neural networks allowed us to identify the most significant parameters that determine the corrosion resistance of alloys. Electrolysis was carried out in a glass cell for a two-electrode scheme using planar positione...

In this study, the antibacterial properties of pharmaceutical grade kaolin modified with copper were tested to determine its suitability to be used in pharmaceutical and cosmetic applications. Both kaolin?s and copper?s antimicrobial activity have been highlighted by multiple researches. The sample was prepared by submerging the kaolin into saturated CuCl2 solution in order to load the nanoparticles with copper, utilizing the cation exchange capacity (CEC). Mineralogical analysis was conducted by X-ray diffraction...

This article describes the design of a compact Wilkinson coupler with an operating frequency of 1000 MHz. This device belongs to the class of power dividers, which are widely used in various microwave systems. The classical design consists of two segments of the transmission line with a length of a quarter of the wavelength, which are connected through the resistance R with a nominal value of 100 Ohms. The presence of resonant segments leads to the fact that the device has large dimensions at low frequencies of th...

Currently the problem of surface water quality is relevant and requires urgent solution. There is an intensive growth of rivers? water using those results in deterioration of water quality and hydrological regime. In the conditions of the Mykolaiv region (Ukraine) local water resources are limited. The present situation is aggravated by anthropogenic pollution of surface and groundwater by utilities and agrarian sector. Monitoring surveys of surface water quality are an important tool for environmental assessment ...

The energy consumes for district or industrial heating and electrical energy are in most of cases concomitant. The paper analyses from the point of view of the First and Second Laws of Thermodynamics the advantages of producing heat and mechanical power each one individually or through cogeneration. It is clearly pointed out that the energy balance induces the idea that the most efficient conversion process is to produce heat in an individual boiler while the mechanical power production in a steam turbine system i...

The main purpose of this scientific work is to review the current methods of multifunctional material design, and to establish approaches based on multiscale non-deterministic analyzes that can be used to model composite coatings. Analyzing of the literature data showed that methods of computer modeling of materials can be classified by the following. The first group represents approaches in which for selected values of functional properties the process of selecting materials is based on a combinatorial search in ...

Silicon carbide is a promising material for heat-loaded units due to its high strength at elevated (up to 1500 °C) temperatures and good thermal conductivity. However, when heated in oxidising media SiC tends to lose its properties, and development of SiC-based materials able to withstand such conditions is a challenging issue. The present research discusses development of a heat- and oxidation-resistant structural ceramics based on SiC with oxide sintering aids. Sintering aids were chosen in ternary systems CaO-A...

An electrolyte for chromium based nano-composite electrolytic coatings (nano-CE?) obtaining has been developed. Nano-CEC was applied on steel of the St 3 brand with constant exposure to ultrasound, electrolyte temperature 50?60°?, current density 7kA/m2 for 1 and 2 hours from two variants of chromium-plating electrolytes, differing in the fact that one electrolyte contained strontium sulfate, in the other ? without it. Quantitative assessment of the corrosion resistance of nano - CEC deposited on steel St.3, was e...

Presently, energy efficiency (EE) improvement is considered a part of the state environmental policy in Russian Federation, an instrument for modernization of national industry and a tool to enhance its environmental performance. This approach holds much promise regarding ceramics manufacturers, where industrial sites are most energy-intensive and are classified as category I objects in terms of negative environmental impact. Since 2010s Russian practitioners have tended to evaluate energy efficiency and environme...

This study aims to investigate the functionalization by pad-dry-cure method of 100% cotton fabrics with colloidal dispersions based on TiO2:N and SiO2 nanoparticles (NPs) in different molar ratios (1:0.5, 1:1, 1:1.5 and 1:2). For the preparation of colloidal dispersions the chitosan was used as stabilizing agent. Self-cleaning performance of the functionalized samples was qualitatively assessed based on Methylene Blue and Brilliant Green stain removal ability under UV radiation. Stain photodegradation efficiency w...

In this paper we present the results obtained regarding the functionalization of the surface of sheepskins using nanocomposites based on reduced graphene oxide - TiO2-Ag and reduced graphene oxide - TiO2-Cu in order to obtain leather with antimicrobial and photocatalytic properties. The nanocomposites were integrated in film forming polymer composites and were applied by spraying on sheepskin surfaces. Sheepskin surfaces were characterized using scanning electron microscopy (SEM), physico-mechanical methods, photo...

The qualitative and quantitative composition of biomass of microorganisms has been studied in key points of artificial biocenosis: water filter, duckweed and pond snail. Metagenomic studies have shown the presence of Bacteroides and Proteobacteria types in all examined systems, however, specific representatives - Actinobacteria, Cyanobacteria, and Bacilliwere also found, respectively. A microflora peculiarity of water filter was the presence of actinobacteria. In the intestine of the pond snail (Lymnaea stagnalis ...

This article describes the design of a crossover whose dimensions are miniaturized using compact elements. Crossover is a directional coupler that allows you to transmit the incoming power to the input diagonally to one output, the rest can be considered untied. Compact units are designed in such a way as to achieve identical characteristics with replaceable lines. The number of connected loops in the crossover design will affect the dimensions and bandwidth of the device. With the help of mathematical modeling, t...

One of the most important characteristics investigated during the obtaining of polymer nanofibers is the mean fiber diameter, which depends on the technological parameters of the electrospinning process. Polyvinyl chloride (PVC) nanofibres were obtained on the NANON-01A, Japan. The following technological parameters were used to obtain nanofibers: voltage is in the range 15 to 30 kV, a solution feed rate is in the range of 0.3 to 1.0 mL/h, a distance between the collector and the tip of the syringe is in range 7.5...

It is known that one of the methods for purifying gas fraction from hydrogen sulfide is amine treatment. Various types of amines are used to remove hydrogen sulphide, carbon dioxide and carbon dioxide from petroleum gases. The choice of specific amine depends on the needs of the process. Mono-ethanolamine (MEA) (C2H4OH) NH2 and diethanolamine (DEA) (C2H4OH) 2NH are commonly used. Both are ammonia derivatives. To develop recommendations on the choice of material from which to make equipment for amine plants, compar...

The process of mixed oxide coatings forming on a high-silicon aluminum alloy in the cobalt-containing pyrophosphate electrolyte by the plasma-electrolytic oxidizing (PEO) method is studied. It was shown that AL25 chemical composition heterogeneity causes the consumption of part of the anode current to homogenize the treated surface, which is reflected in minimizing the content of doping components at the initial processing stage. It was established the growth of mixed oxides Al2O3·CoxOy relative mass to be a funct...

Adjustment of compositions and processing techniques, mainly ? firing conditions, has been a key route for ceramics performance improvement. The present research addresses sintering process of alumina ceramics with an additive in system that was studied by non-isothermal method. Experimental samples shaped as cylinders 25 ? 6 mm in size were obtained and sintered by consequtive firings in air at heating rates q1 = 1,0 and q2 = 3,0 °?/min without curing and quenched in air. Linear shrinkage (? = ??/?, hereon ? ?) a...

Novel micro and nanostructured bioemulsions were created by innovative technologies based on fibrillar cellulose/titanium dioxide/(surfactants mixture: dodecandioyl-diglycine and sucrose diester/ethanol/water, for improved surface properties development with applications in leather industry. The high potential of using cellulose as a material for various applications: in membrane technologies for pollutant absorption, in pharmacy, etc. opens the way to obtaining new added value materials (hybrid micro and nanocomp...

Ni-P-Sn layers were deposited on the steel strip, with less carbon, by electroless method. An electrolyte based on nickel chloride, sodium hypophosphite, tin chloride and additions for bath optimizing were utilized. The influence on the deposited layers characteristics of different amounts of tin chloride in the nickel bath, respectively, 0.1g/L and 0.4g/L was studied. The conditions for electrolyte formation and optimum working parameters: pH and temperature were set. Ni-P-Sn layers were characterized by comparis...

Currently, the issue of the possible negative influence of nanoparticles on human health is inadequate in comparison with the presentation of their positives. Although there is no questioned their undeniable importance on the other hand experts agree that the precautionary principle and related measures are missing and necessary. The paper presents the pilot results of a grant project focused at the creating a methodological guideline aimed at increasing the level of occupational health and safety management at wo...

The influence of ?-ferrite amount ferrite in AISI 321 steel on its general corrosion, critical pitting temperature and potential in simulated circulating waters. The samples were made in the form of rectangular 3x3x1 mm parallelepipeds by cold mechanical method. Surface of the samples was subjected to electro-polishing. The amount of ferrite phase was determined by empirical formula. It was established, that after electromagnetic saturation of the samples, ?-ferrite content in five heats of AISI 321 steel was calc...

Previously we have developed the PLGA nanoparticles loaded with doxorubicin (PLGA-DOX NP) that demonstrated a high anti-tumor effect against the rat glioblastoma in the preclinical studies and is now being evaluated in the clinical phase II study. This formulation was obtained by a generally accepted homogenization ? solvent evaporation technique followed by freeze-drying. The purpose of the present study was to explore the feasibility to simplify the process of the nanoparticle preparation by replacing a freeze d...

The study was conducted to study the effect of cerium dioxide nanoparticles on the survival of zebrafishand the microbiome of their intestines. With respect to the intestinal microbiome in the control group, it was registered that the majority of the identified bacteria belonged to Proteobacteria. A peculiar action of CeO2nanoparticleson the intestinal microbiota was an increase in the number of Firmicutes, in particular, Bacilli class bacteria, and a decrease of Proteobacteria phylum, it was manifested in the flu...

The paper describes a new design of a directional coupler with four plug-in quarter-wave loops. Four loops increase the operating frequency band several times, but the area of the device also grows by two quarter-wave segments in length. It is not always possible to use such a large device area, for this reason, techniques are used to reduce the size of the device with minimal loss in its characteristics. Using miniaturization, which is the use of compact structures, it was possible to reduce the size of a quarter...

In this paper we describe the synthesis and characterization of nano-sized TiO2 particles supported on sepiolite fibres with sepiolite to TiO2 weight ratios of 30:70, using sepiolite from Korinthos, Greece. Sepiolite - TiO2 nanocomposites were prepared by deposition of anatase form of TiO2 on the sepiolite surfaces using a sol?gel method with titanium isopropoxide as a precursor under hydrothermal treatment at 180 °C. The characterization includes phase composition, particle morphology, while the physical properti...

Nowadays, modern technical solutions in various spheres of human activity from the opto-electronics up to nanobiotechnology are increasingly dependent on the level of technology. Applied research on nanomaterials plays a key role in the development of nanotechnologies. The nanostructured silicon is one of the materials attracting the special attention of researchers in various applied areas. A new and widely discussed application of nanostructured silicon is a possibility of their usage in the process of efficient...

Based on the exergetic analysis the paper analyses the conduct of a simple Linde cryogenic refrigeration cycle looking for its weaknesses and trying to find ways for operating or structural improvements. The exergetic analysis reveals that a major exergy destruction is due to heat transfer across a finite temperature difference in the recuperative heat exchanger. The optimization procedure points out that this exergy destruction reaches a minimum if the temperature difference between the high (hot) and low pressur...

The goal of this work is to study the processes of producing carbon aerogels, silica-carbon aerogels and CNT-silica aerogels and search for new areas of their applications. To achieve this goal, aerogels using the sol-gel method and the supercritical drying process were synthesized. The analysis of the obtained aerogels was carried out using the methods of nitrogen porosimetry and scanning electron microscopy. In addition, a software that uses cellular automaton models to generate virtual structures of the studied...

It was found that the mechanically activated highly dispersed component based on saponite-containing waste of the diamond industry allows us to improve the physicomechanical characteristics of fine-grained concrete due to the formation of hydrosilicates of additional generation. According to the working hypothesis, the resulting new formations are submicrocrystals of the tobermorite group. The objective of this study was to identify the products of the hydration of clinker minerals with a component on the basis of...

Aerogels are promising materials for use in various industries such as chemical, pharmaceutical, medicine and food industry. These highly porous materials have unique properties, including high adsorption capacity, which makes it possible to successfully impregnate various substances into aerogels: active pharmaceutical ingredients (APIs with low solubility and bioavailability), various oils (for example, high volatile), additives for the food industry (vitamins and aromas) and many others. The aim of present inve...