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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 ...

The bactericidal properties of silver and its compounds are known for a long time. Silver has antimicrobial properties against a wide range of microorganisms, not only bacteria, but also some fungi, as well as viruses. However, several mechanisms have been identified for the formation of resistance to silver in bacteria. It?s relevant to search for new reagents, which would increase the aggressive stability of the argentum?s compounds. Purpose is study of the influence of various chemical nature SAS on the aggrega...

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...

The purpose of the paper is to obtain a new composite material based on chemically functionalized nanoparticles dispersed in plastomer matrix. The dispersion of the ZnO nanoparticles in a plastomer matrix (PETr) leads to a high-performance polymeric material with multi-functional, antibacterial, and plastomer-specific processing properties. In this paper, elastomeric nanocompound materials were selected, due to performance properties such as: antimicrobial, resistance to aggressive chemical agents, mechanical prop...

Nowadays, emulsions have been increasingly studied due to their application in different fields such us cosmetic, agriculture, pharmaceutical, paint and oil industries. Essential oils were widely used in the cosmetic industry as antimicrobial and antioxidant agents. This study investigated essential oil entrapment in beeswax in order to prolong its biological activities as oil in water (O/W) emulsion. Moreover, one of this work aim was to achieve stable beeswax-essential oil (extracted from Rosmarinus Officinalis,...

The ultimate goal of this study is to obtain antimicrobial textiles, useful in various skin infections with different bacterial strains, due to the unique properties of contained essential oils, such as: antimicrobial and antiinflamatory effects. Four different matrices of biologic active systems in forms of stable emulsions were used in this study, namely: bee wax ? essential oil, chitosan ? agar ? essential oil, xanthan gum ? essential oil, xanthan gum ? gelatin ? essential oil and four different types of essent...

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...

Directional couplers implemented on two pairwise identical segments of the transmission line, have only one working bandwidth. In order to organize the performance of the structure on two ranges or more, it is necessary to make design changes to the standard device. For example, for operation at two frequencies, idle plumes are added to the design of the coupler. However, this has further increased the dimensions of the coupler, especially at low frequencies, and in some cases the design may be practically unsuita...

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...

Using the open-source library for calculations in the field of kinetics and thermodynamics Cantera, a software module has been developed. Computer simulation of dry reforming of methane in a membrane reactor-contactor has been performed. The one-dimensional mathematical model of gas flow in a porous catalytic coating is used. The influence of a number of parameters, such as characteristics of pores of catalytic membrane coating, and the temperature and the flow rate of the gas mixture on the dry reforming of metha...

Atmospheric air is the primary component used in air separation plants. Wet air is a mixture of dry air particles and vaporous water particles, a mixture in which the components do not chemically interact and are thought to be approximately perfect gases. Atmospheric air to be processed in a separation unit needs to be cleaned of all impurities that can cause damages in the main components of the plant. The hazardous impurities that can be found in the atmospheric air used to generate oxygen, nitrogen and rare gas...

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...

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 aim of this work was to obtain new medical biomaterials based on a biocompatible polymer polytetrafluoroethylene (PTFE), modified with the drug, ketoprofen (KP), and gold nanoparticles (Au NPs). The biological inertness of PTFE, hydrophobicity, elasticity, low weight prevents sticking to wounds and makes fibrous materials based on it ideal for dressing and obturators. Ketoprofen gives anti-inflammatory properties to the material, while Au NPs provides it with antibacterial ones. Biomaterials based on porous PT...

New materials based on Au and Ag nanoparticles stabilized in a matrix of microcrystalline and bacterial cellulose were prepared for medical applications. Au and Ag nanoparticles were synthesized in i-PrOH by metal vapor synthesis (MVS) and incorporated into the polysaccharide matrix using metal-containing organosol. The MVS is an efficient route of purposeful synthesis of metallic nanoparticles and their derived composites. Microcrystalline cellulose brand Avicel PH-101 with a polymerization degree of 180 and an a...

Molecular simulation methods were used to describe the spiral-structure of halloysite (7 A) loaded with irinotecan in Materials Studio modeling environment. Halloysite is a clay mineral commonly used as a drug delivery system for a variety of molecules due to its suitable characteristics and its morphology. Irinotecan is a semi-synthetic drug used in the treatment of colorectal cancer and exists in an active lactone form and an inactive hydroxyl-acid anion form[1]. In this work, the anionic form of the irinotecan ...

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 ...

Micro and nanoparticles of titanium dioxide are nowadays produced worldwide for a range of applications. In our project we focus on potential use of titanium dioxide particles as UV absorber (anti-UV protective coating) for wooden construction structures. We investigate the influence of different synthesis methods on particles? morphology. Hence, material characterization has an important place in our research. Electron microscopy is a powerful tool to obtain information about the morphology of particles and their...

The paper deals with a design and a method of milling of the invention called ?Milling device for mechanical treatment process of fine particles?. The milling device for mechanical treatment process of fine particles according to the present invention consists of a lower flange with a milling chamber having an external part and an internal part being fixedly attached to said lower flange wherein an elastic doctor blade with brushes is arranged within said internal part. The elastic doctor blade with brushes is fas...

Directional couplers can divide the input power between its outputs in different proportions. This is due to the ratio of wave resistances between two pairs of quarter-wave segments. Due to the fact that at frequencies of 2 GHz and lower couplers are also actively used, it is necessary to take care that their dimensions satisfy the radio system where they will be installed. Due to the fact that it is not always possible was investigated miniaturization as an opportunity to reduce the area occupied by the branch wh...

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...

New ways in the field of extinguishing by solid extinguishing is aerosol fire fighting originally developed in the 1970s by the Russian space research agency called ?SOJUZ?. More significant development in the aerosol fire extinguishers usage occured in Europe in the 1990s. Carbon as basic element of organic compounds with two allotropic modifications can be found in various modifications like diamond and graphite. Fullerenes as the third modification was discovered in 1985. Detailed analytical researches have fou...

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...

Inorganic arsenic is in very small concentrations a common constituent of surface and groundwater. However, its increased concentration may pose a significant risk to human health in connection with its carcinogenicity (a proven human carcinogen). Therefore, it is necessary to address the reduction of its concentration in drinking water using the most efficient and financially undemanding techniques. The paper analyzes current and new trends in the field of removal of arsenic from drinking water. It focuses mainly...

Treating depression is a complex process, which includes medical treatment and also psychotherapeutic approach. These two approaches are working together. There is a large scale of known treatments for depressive disorders, which had been developed since the 1950s and the therapeutic effectiveness and patient tolerance were assessed through generations. Among the studied variants, anorganic products had been Among the studied variants, anorganic products had been Among the studied variants, anorganic products had ...

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...

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...

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...

Acrylic derivative-based superabsorbents are widely used currently in agriculture as the soil conditioners, plant growth regulators, etc. Their usage has a positive effect on the growth and survival of the plants cultivated in the arid regions. However, the effects of hydrophilic acrylic polymers on the soil microbiocenosis still remain unknown. The influence of the moisture-absorbing acrylic acid-based hydrogels with different concentration of bentonite filler was studied on the soil microbiota. N,N-methylenebisa...

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...

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...

Directional couplers are widely used in microstrip technology, but their dimensions are tied to the operating frequency. Since the smaller the frequency, the longer the longitudinal length of the quarter-wave segments and the greater the overall dimensions of the coupler. For this reason, use miniaturization, which allows to reduce the area occupied by the device on the substrate, with negligible loss in performance. In addition, there is an economy of the material used in the manufacture of the microstrip device....

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...

Microstrip directional couplers are made on microwave substrates, which consist of various dielectric materials. With a decrease in the operating frequency, the dimensions of the coupler increase, and more material is required for their manufacture. To reduce the consumable material, you can use different approaches to miniaturize the couplers, this will reduce the size of the device while maintaining its characteristics. So this article presents the results of research to reduce the occupied area of a flat crosso...

In the vegetable growing field, the germination is an important indicator in the appreciation of seeds quality. The process takes place over a variable period of time being influenced by a number of factors such as species, environmental conditions and the treatment applied to the seeds. We used citrate - stabilized gold nanoparticles to prevent the occurrence of fungi and to stimulate the germination process of carrot seeds. The gold nanoparticles were synthesized by mixing and heating aqueous solutions of chloro...

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...

A passive method is proposed in this research for minimization of the temperature drift of a strapdown inertial navigation system with fiber optic gyroscopes and accelerometers by means of reduction of the temperature differences between the structural components of individual gyroscopes as well as between gyroscopes and accelerometers. For this purpose, theoretically possible use of nanostructured composite materials based on carbon nanotubes and characterized by increased thermal conductivity in individual struc...

This research deals with the aspects of use of the heat balance method for calculation of three-dimensional non-uniform non-steady temperature fields of complex optoelectronic systems through the example of a measuring unit based on fiber optic gyroscopes and microelectromechanical accelerometers. The main principles of and approaches to development of a mathematical model of the temperature field of the unit under consideration on the basis of the heat balance method have been set forth. The adequacy of the devel...