We study the biomedical Ti–18Nb–4Zr–
x
Si cast alloys with a silicon content of 0.5–1.5 wt.%. Quenching in water was carried out within the temperature range 900–1200°С with durations of holding ...equal to 5 min and 1 h. It is discovered that the procedure of heating of these alloys to the temperatures of quenching leads to the decay of nonequilibrium phases, and the silicon content is redistributed between the phases in a solid solution and silicides. Since almost all silicon is bound with zirconium and titanium and form silicides, the hardness of the Ti–18Nb–4Zr–
x
Si alloys mainly depends on the amount of silicides and constitutes 26–28 HRC. Moreover, its maximum values are reached for the alloys with eutectoid compositions containing 0.8–1.2 wt.% Si characterized by the most intense release of finely divided silicides. The increase in the silicon content of the hypereutectoid alloys leads to an increase in the sizes of silicides, as well as to the formation of larger amounts of the β-phase in the as-cast Ti–18Nb–4Zr–
x
Si alloys, and as a result, their hardness noticeably decreases. For low quenching temperatures (within the range 900–1000°C), the complete eutectoid destruction accompanied by the formation of relatively large stable (Ti, Zr)
3
Si silicides leads to a decrease in hardness < 25 HRC. In the course of quenching of the as-cast Ti–18Nb–4Zr–
x
Si alloys at temperatures ≥ 1100°C, we observe the formation of more finely divided silicides, which increases the level of hardness of the eutectoid alloys up to 38–39 HRC. The observed changes in the parameters of the α″-phase demonstrate that, as a result of partial dissolution of silicides in the course of quenching at 1200°C, silicon passes into a solid solution and the amount of large silicides on the grain boundaries increases. Therefore, the level of hardness of the analyzed quenched alloys decreases.
The process of carburizing is well-studied and is one of the traditional processes of the thermochemical treatment of steel. The process has disadvantages such as high energy consumption, long ...exposure time, complicated processing of large products and surfaces. Electrospark deposition with a carbon electrode is proposed as an alternative process. The carburizing extent and the working layer depth can be increased when the process is used in the ultrasonic vibration field. A resonant vibration introducing circuit with a standing wave generated in the specimen tested is implemented to identify the influence of specific ultrasonic wave areas on the hardened layer formed. The highest carbon saturation of the surface layer was found in the standing ultrasonic wave oscillation node area, where cyclic stretching and compression of the medium contribute to the excess phases release. The carbon in the martensite estimated by the c/a ratio was 0.78% by weight. The highest cementite layer depth and transition zone size are in the ultrasonic wave antinode area, where the highest dynamic medium particles displacement is observed under the influence of vibrations. It is shown that the base metal structure component dispersiveness is responsible for the increased hardened layer depth.
The data obtained earlier on the Mannich bases derived from natural and synthetic phenols are summarized, the structure—antioxidant activity relationship is analyzed, and the most active compounds ...among these bases are identified. The influence of the nature and position of aminomethyl substituents on the hemolytic activity (erythrotoxicity) is considered. The high antioxidant and membrane-protective activity exhibited by some Mannich bases in the model of oxidative hemolysis of mammalian erythrocytes is explained by the presence in their structure of a
N
-alkyl group or a fragment of a heterocyclic amine, which affects the lipophilicity of the compounds and the interaction with the cell membrane.
This review is devoted to free electron lasers (FELs) and their development research at the Budker Institute of Nuclear Physics (INP), SB RAS. Basic principles of FEL physics are considered. Selected ...studies from forty years of research are presented. The unique Novosibirsk FEL research facility is briefly described.
The transforming growth factor β1 (TGFβ1), whose level may depend on the polymorphism of the TGFB1 gene, is involved in the formation of myocardial fibrosis. Myocardial fibrosis in a cardiac ...allograft may lead to a heart's structural and functional remodeling and subsequent dysfunction. The frequency of occurrence of alleles and genotypes of the TGFB1 gene polymorphic regions rs1800469, rs1800470, and rs1800471 in heart transplant recipients and their association with graft myocardial fibrosis were analyzed. Carriers of the CC genotype (p = 0.023, OR = 0.12, 95% CI: 0.017-1.0), and more often the G allele of rs1800471 (p = 0.023, OR = 7.76, 95% CI: 1.0-60.20), were found among heart transplant recipients less frequently than among healthy individuals. In patients with ischemic heart disease (IHD), the GG genotype was less common (p = 0.035, OR = 2.68, 95% CI: 1.061-6.793), while the A allele of rs1800469 was found more frequently (p = 0.035, OR = 0.37 95% CI: 0.148-0.942) than in patients with dilated cardiomyopathy (DCM). In heart transplant recipients with the AA genotype of rs1800470, myocardial fibrosis, verified by endomyocardial biopsy, was detected more often than in carriers of the G allele (OR = 10.4, 95% CI: 1.152-94.538, p = 0.013). The revealed differences suggest a relationship between TGFB1 gene polymorphism and graft myocardial fibrosis. Studies on a larger group of patients would make it possible to characterize the influence of genetic factors on the formation of myocardial fibrosis in heart transplant recipients.
The reaction of
o
-isobornylphenols with bismuth(
iii
) nitrate provided
o
- and
p
-nitrophenols, the reduction of the nitro group of which with zinc dust in acetic acid led to the corresponding
o
- ...and
p
-aminophenols. A comparative evaluation of antioxidant properties was performed for the newly obtained aminophenols with an isobornyl substituent using
in vitro
models. It is shown that the proposed modification of
o
-isobornylphenols is promising for obtaining new highly active inhibitors of oxidative processes.
In the article modern scientific and theoretical positions concerning determination of the effectiveness of soil protection measures on agricultural lands are investigated. It is analyzed that the ...protection of land from degradation is one of the most important problems of agriculture, as this process leads to a significant decrease in soil fertility and crop yields. That is why in today's conditions, when the protection of agricultural land became urgent and a priority task, the scientific substantiation of the economic assessment of the damage caused by the degradation of land to agriculture, as well as the development of methods for determining the economic efficiency of the most progressive soil protection measures, technologies and complexes based on their overall Comparative evaluation. It was established that ground protection measures are a system of various measures aimed at reducing the negative degradation effect on the soil cover and ensuring the preservation and reproduction of soil fertility and integrity, as well as increasing their productivity as a result of rational use. The economic essence of soil protection measures is the economic effect achieved by preventing damage caused by land degradation to agriculture, as well as for obtaining additional profit as a result of their action. The economic effectiveness of soil protection measures means their effectiveness, that is, the correlation between the results and the costs that they provided. The excess of the economic result over the cost of its achievement indicates the economic efficiency of soil protection measures, and the difference between the result and the expenditure characterizes the economic effect. Ecological efficiency is characterized by environmental parameters of the soil cover, namely: the weakening of degradation effects on soils; improvement of their qualitative properties; An increase in production without violation of environmental standards, etc. Economic efficiency reflects the use of land resources when performing soil protection requirements. Social efficiency is determined by the improvement of social organizational and territorial conditions of population living: preventing losses of clean products due to soil contamination; reduction of payments from the social insurance fund; Reduction of expenses of the society for treatment of workers in connection with pollution of soils, etc. When introducing soil protection measures, a soil protection effect is necessary under the condition of an increase in productive capacity of the land only if it is differentiated according to the soil, relief, climatic conditions and specialization of agricultural enterprises with the obligatory application of anti-degradation measures. Therefore, in today's environment, the organization and planning of soil protection measures should take place on the basis of a regional program-targeted approach. Its essence consists in analyzing the initial state of the region, identifying problems and formulating the goal, identifying their priorities. This makes it possible to make an effective decision on the implementation of an optimal set of soil protection measures. Consequently, the general criteria for the economic evaluation of the effectiveness of the system of soil protection measures are the preservation and improvement of the qualitative characteristics of agricultural land and the environment and the increase of production per unit of land at the least cost. Indicators of economic efficiency of various types of soil protection measures play an important role in the design and implementation of soil protection measures against degradation. With the proposed approaches, the relevant bodies of land relations, in particular, when developing projects and other documentation on land management, as well as directly landowners and land users, can reasonably plan some or other measures and allocate the necessary material resources for their implementation. This ensures the restoration of degraded lands and the timely prevention of degradation processes.
In the reported study we prepared gallic acid modified γ-AlOOH nanoparticles. We proposed mechanism of phenolic compounds binding on the alumina, suggesting covalent and electrostatic interactions. ...Most of the properties of alumina nanoparticles (NPs) are unchanged, but there is partial reduction of surface charge. Prepared samples are colloidally stable hydrosols. It allowed us to perform biological studies on cellular and non-cellular models, which showed nontoxicity of both pure and hybrid γ-AlOOH nanoparticles. Furthermore, pure alumina NPs exhibit antioxidant properties, which are enhanced after gallic acid immobilization on their surface. Also, hybrid alumina-gallic acid NPs showed membrane-protective activity.
Pure and modified with gallic acid (GA) alumina nanoparticles NPs are non-cytotoxic, show antioxidant activity, which is enhanced after GA immobilization on alumina surface. Also, these hybrid organic-inorganic NPs are membrane-protective of oxidative hemolysis. Display omitted
•Gallic acid binds to γ-AlOOH nanoparticles (NPs) electrostatically and covalently.•Pure and modified with gallic acid (GA) alumina NPs are non-cytotoxic.•Pure γ-AlOOH nanoparticles showed antioxidant activity, GA enhanced it.•Modification of NPs with GA makes them membrane-protective of oxidative hemolysis.•Prepared samples are colloidally stable hydrosols without additives.
Complexation of a copolymer of styrene and 5-methyl-5-hexene-2,4-dione with cobalt chloride in dimethylformamide occurs with the formation of metallopolymers of two types, namely with intra- and ...extramolecular binding of β-diketone groups, the ratio of which depends on the concentration of the initial macromolecular ligand. It has been established that the polymer metal complexes differ in the geometry of the coordination unit, molecular weights, and metal content resulting in the different reactivity to initiation of graft radical polymerization of methyl methacrylate.
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