The role of cysteine in the formation of domain structures of papain and legumin in peas, involved in limited proteolysis

The limited use of plant proteins for food is explained by their low bioavailability and poor digestibility by enzymes of the gastrointestinal tract. Partially reproduced enzymatic processes of limited proteolysis that occur during seed germination are used to modify and improve the edibility characteristics of seed proteins. The present work discusses the possibility of reducing the duration of seed germination processes by optimising the conditions and parameters of limited proteolysis. To optimise manufacturing high-quality final product, enzymes (additional to the natural enzymes in the seed) and proteolysis conditions (in this case, temperature), as well as added substances (hydrolysis activators), were selected. The influence of cysteine on the formation of domain structures of proteins (enzymes and globulins) was evaluated. The proposed expressions can be used to determine those fragments of protein molecules that form stable domains and become unstructured when exposed to enzymes. Optimal conditions for limited proteolysis were identified based on the physical mechanism of action of papain-like proteolytic enzymes on pea legumin LegA (3KSC, CAA10722). It is shown that the decomposition of protein secondary structures takes 6–8 times longer, since the formed hydrogen bonds limit the access of enzymes to the corresponding amino-acid residues. It is also demonstrated that the decomposition of hydrogen bonds, e.g. by preliminary heat treatment of proteins, will broaden the prospects for limited proteolysis.

Development of technology for the production of a lightweight observation and protective container (LOOK) made of nanostructured ultra-strength steels

The article contains results of research and analyses concerning application of nanostructured bainitic steel in the form of plates for manufacturing of armour components. The presented results of examination of microstructure and properties include a wide range of laboratory experiments and industrial tests, which resulted in the achievement of the assumed functional properties. In the period of 2017-2021, a scientific and industrial consortium consisting of Łukasiewicz – Institute of Ferrous Metallurgy (leader); WITPiS, Tarnów Mechanical Works, Alchemia and Heatmasters Poland carried out a project funded by the POIR 04.01.04 programme aimed to develop the design and to manufacture an observation and protective container with a specified resistance to penetration by armour-piercing projectiles and with a lower mass of steel armouring in relation to that currently produced. The aim of the project was achieved by using armour plates made of nanostructured bainitic steel (nanobainitic), which are characterised by high resistance to high-energy impact concentrated in a small area. The technological tests carried out in the project mainly concerned the development of a new container and industrial technology of armour plates production and their application in the armour of this container. Based on the results of investigation of the semi-industrial scale material, the optimum chemical composition for industrial scale melting and casting was determined. An industrial technology for the production of plates of nano-structured bainitic steel was developed, which includes the following processes: smelting and casting, preliminary heat treatment and ingot hot processing, as well as hot rolling, final heat treatment, and surface treatment. A test batch of the material in the form of 1500×2470 mm armoured plates was fabricated under industrial conditions. The final result of the project is a container armoured with bainitic nanostructured steel plates with implementation documentation and a technology for producing armoured plates from this steel under the technical and technological conditions of domestic steel manufacturers.

RESEARCH OF THE PROCESS OF EXTRACTION OF BLACK CUMIN OIL WITH PRELIMINARY HEAT TREATMENT

The aim of the study is to increase the yield of oil from black cumin seeds. The results of studies of the influence of technological parameters - temperature and duration of drying of black cumin seeds on indicators of the yield of oil, cake and moisture removal from seeds are presented. The optimal technological parameters of the influence of the preliminary heat treatment process on the indicators of the maximum oil yield, acid number, color, and oil moisture have been established. The variable parameters were the temperature from 80 to 130 °C and the duration of the heat treatment process from 5 to 60 minutes. The possibility of increasing the oil yield by 6,11% has been shown. For this, the drying process must be carried out at a temperature of 100 °C and a process duration of 15 minutes. At the same time, the degree of oil extraction increases from 59,13% to 75,24%, the acid number decreases to 2,98, humidity to 0,12%, and color to 40.

Substantiation into Parameters of Carbon Fuel Production Technology from Brown Coal

Technological solutions for brown coal processing, thermal influence on it at temperature change, thermo vacuum drying are analysed and qualitative and quantitative characteristics of semi – coking products are studied. The parameters of crushing and thermo vacuum drying of brown coal, heat treatment and cascade separation (electrostatic and magnetic) are substantiated. Studies on the manufacture of a pilot batch of carbon fuel with high quality characteristics are performed. Cascade treatment of heat-treated brown coal on electric and magnetic separators allowed to obtain a concentrate with ash content from 17.72 to 22.8%, volatile yield ≤ 35%, higher heat of combustion from 7256.1 to 7523.6 kcal/kg. It is determined that favourable modes of preliminary heat treatment of brown coal samples are in the temperature range of 200-400°С. The established characteristics of the obtained solid fuel correspond to the gas group of thermal coal. The obtained technological solutions for the processing of brown coal can be the basis for the manufacture of an industrial line, taking into account the thermo vacuum installation for further implementation in enterprises using carbon fuel.

NEW STEELS AND TECHNOLOGIES FOR NITRIDED PARTS OF LONG LIFE MACHINES

The analysis of the used steels for nitrided parts is carried out. On the basis of a new methodology for increasing the strength of structural steels and parts, new scientific approaches and practical solutions are proposed and considered for the creation of gear wheels strengthened by nitriding both when using aluminum containing steels and a new material, 40ХМФА (40KhMFA) steel, that does not contain aluminum. To improve the efficiency and manufacturability of parts production from aluminum-containing 38Х2МЮА (38Kh2MYuA) steel, widely used in mechanical engineering, a fundamentally new technology of preliminary heat treatment of part blanks, “incomplete quenching”, has been developed, which provides both an increase in the machinability and accuracy of large-sized gear wheels, and an increase in strength due to the elimination of flaking of nitrided layer. The research results are presented on 40ХМФА (40KhMFA) steel, which does not contain aluminum, has increased heat resistance, hardenability and workability of parts, as well as the characteristics of the hardened layer. The nitrided layer of gears with a thickness of 0.5–0.7 mm does not contain brittle components, which, with a core hardness of 300–320 HB, also excludes its flaking and subsequent destruction of parts. The use of 40ХМФА (40KhMFA) steel makes it possible to solve the problems of reliability and life of large-sized nitrided gears, but it is also promising for the entire range of gears with internal gearing, as well as parts of movable spline gearings and fine-modular gears in order to replace carburizing with nitriding.

Method for producing fruit paste using innovative equipment

A method for the production of multicomponent fruit and vegetable paste has been developed. All components were selected considering the content of physiologically functional ingredients. The method is distinguished using the developed innovative equipment: a multifunctional apparatus for the implementation of preliminary heat treatment of raw materials; rotary film evaporator for concentrating puree. The developed devices are distinguished by increased resource efficiency due to heating with a low-temperature film electric heater with a temperature regime in the range of 45-70 °C. The study of structural and mechanical parameters and organoleptic evaluation of the prototypes allowed to reveal the rational content of raw materials in the developed paste: apples – 30%; viburnum – 20%; black chokeberry – 20%; pumpkins – 20%, beets – 10%.

Experience and prospects of use of structural steels for nitridated gears

The experience of using known and new steels to improve the manufacturability and strength of the main parts of machines, hardened by nitriding, is generalized. New approaches to manufacture of gear wheels hardened by nitriding, both when using aluminum-containing steels and a new material, steel 40ХМФА, are considered. To improve the efficiency and man ufacturability of parts production from aluminum-containing steel 38Х2МЮА, widely used in mechanical engineering, a fundamentally new technology of preliminary heat treatment of workpieces of parts – “incomplete hardening” has been developed, which provides both an increase in the machinability and accuracy of large-sized gear wheels, and an increase in strength due to the elimination of the brittleness of nitrided layer. The high hardness of the nitrided surface of the parts – up to 900 HV – also ensures high wear resistance of the parts. Gear wheels made of new aluminum-containing steel 20ХН4МФЮА solidified at the nitriding stage, have strength characteristics equal to cemented parts, which allows not only increasing the bearing capacity of a number of products, but significant simplification of the technology of manufacturing precise parts that are complex in shape, replacing carburizing with nitriding, thereby eliminating the necessary after-carburizing finishing operation – grinding. Steel 40ХМФА, which does not contain aluminum, has increased heat resistance, hardenability and machinability of parts, as well as the characteristics of their hardened layer. The nitrided layer of gears 0.5–0.7 mm thick does not contain brittle components, which, with a core hardness of 300–320 HB, excludes its “flaking” and subsequent destruction of parts. The use of 40ХМФА steel makes it possible to solve the problems of reliability and service life of large-sized nitrided gears, but it is also promising for the entire range of gears with internal gearing, as well as parts of movable spline gearings. These characteristics also in some cases allow replacing the carburizing of gears (modulus less than 4 mm) by nitriding when using 40ХМФА steel.

Influence of the Melt Treatment Method on the Properties of Cast Iron

The article is devoted to studying the effect of liquid melt treatment with a substance having high affinity with hydrogen – lead-base silumin. Taking into account that gases (hydrogen, nitrogen and oxygen) are present everywhere, including alloys, a series of experiments was carried out on treating melt of blast furnace iron with substances having great affinity with hydrogen. It is established: when treating melt with lead-base silumin in the low-temperature test interval, there is a slight increase in the linear expansion coefficient (LEC) at 100°C, compared with the initial one, to 8.210-6, deg-1. In the temperature range of 100-150°C LEC decreases to a minimum value of 7.210-6, deg-1. In the average temperature range of 150-300°C, a sharp, anomalous increase is noticeable, compared with the initial one up to 15.5210-6, deg-1. When studying the microstructure of cast iron after processing the melt with lead silumin, the formation of ledeburite structure is stated. Samples treated with lead-base silumin were subjected to cementation by feeding water steam at 900°C for 1-5 hours. It should be noted that, in the temperature range of 50-150°C, the values of the linear expansion coefficient lie almost in a straight line in the entire field of study. The coefficient varies from 10.810-6, deg-1 at 50°C to 13.710-6, deg-1 at 450°C. Preliminary heat treatment of cast iron in the carburizer made by the Bondyuzhsky plant with water steam smoothes anomalies of LEC and increases its initial values, and grinds perlite and cementite as well. Subsequent quenching in water with a temperature of 1000°C significantly changes the linear expansion coefficient of cast iron. Hardening of samples after cementation sharply reduces the linear expansion coefficient in the test range of 150-200°C, and in the temperature range of 350-450°C negative values of LEC are observed. Thus, it can be concluded, that treating the melt with lead-base silumin, cementation in the medium of the carburizer made by the Bondyuzhsky plant and subsequent hardening leads to sharp changes of the linear expansion coefficient up to negative values. The identified properties suggest the possibility of using cast iron where it is necessary to constancy of LEC and there are no requirements for the weight of the product.