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Amongst functional materials, shape-memory alloys occupy a special place. Discovered in the beginning of 1960th in XX century, these alloys attracted quite an attention because of the possibility to restore significant deformation amounts at certain stress–temperature conditions due to the martensitic diffusionless phase transformation involved in a process. It was possible to exploit not only the so-called ‘shape-memory’ effect, but also superelasticity and high damping capacity. Over the years, more than 10 000 patents on shape-memory alloys were filed, appreciating not only the possibility to exploit energy transformation to ensure the response (feedback) at the change in independent thermodynamic parameters (temperature, stress, pressure, electric or magnetic field, etc.), but the significant work output as well. Applications ranged from different gadgets to automotive, aerospace industries, machine building, civil construction, etc. Unfortunately, the structural and functional fatigue restricted successful business applications to the medical sector with nitinol shape-memory alloy (different implants, stents, cardiovascular valves, etc.). Emerging high-entropy shape-memory alloys can be considered as a chance to overcome fatigue problems of existing industrial shape-memory alloys due to their specific structure that ensures superior resistance to irreversible plastic deformation.

An electron-microscopic, optical and morphometric study of a series of negatives of the microvessels of the blood microcirculatory tract (MCT) of the myocardium of the complex «left ventricle + interventricular septum» (LV + IVS) of Wistar rats aged from birth to 45 days was carried out. In a series of electron microscopic images (50 negatives of (6.5 x 9) cm2 in size, obtained at a magnification of an electron microscope of 2000x ), the relative volumes (%), absolute volumes (μm3) and average daily growth rate (μm3/ day) of MCT, capillaries, complex of microvessels (venules + arterioles). The obtained digital morphometry data made it possible to determine the regularities of the development kinetics of MCT components in the myocardium of rats during their early postnatal development. It was established that in the time interval (birth to 45 days) of the postnatal development of Wistar rats, the structural and functional elements of the blood-flowing MCR of the myocardium gradually reach their final development. For 45 days after the birth of rats, the dominant component in the blood MCT of the myocardial complex (LV + IVS) is the capillary link. In the process of postnatal angiogenesis, the source of the formation of arterioles and venules in the blood MCT of the myocardium (LV + IVS) are the existing capillaries. Intensive development of the capillary link in the MCT of the myocardium occurs during the first 10 days after birth of rats. During this period of time, the average daily growth rate of the absolute volume of capillaries in the MCT of the myocardium increases (from 0.20 to a maximum of 0.915) x109 μm3 / day. Gradual development of the microvascular complex (arterioles + venules) and increase in their absolute volume in the MCT of the myocardium occurs during the first 25 days after birth of rats. During this period of time, the average daily growth rate of the absolute volume of the microvascular complex (a + v) increases ≈ 52 times (from 0.006 to a maximum of 0.310) x 109 μm3 / day. In the MCТ of the myocardium of newborn rats, the ratio of microvascular volume (a + v) / cap was 1:44.1. Within 45 days after the birth of rats, there is a significant increase of microvascular volume (a + v) / cap in the MCT to 1: 3.1.

Shape-memory alloys belong to the functional materials, which exhibit shape memory, superelasticity and high damping-capacity phenomena. Cu-Al-Mn shape-memory alloys remain of particular interest as they show good machinability and are much cheaper than nitinol. In addition, their functional performance is quite attractive as well. The present paper is dedicated to the changes in shape memory and internal friction induced by the grain-size reduction in low-temperature cast Cu69.26Al25.86Mn4.88 alloy. [ABSTRACT FROM AUTHOR]

After 15 days of postnatal development of rats, in cardiomyocytes (CMC) of the left ventricle there is a longitudinal splitting of myofibrils, which leads to an increase in their number in the contractile apparatus (CA). In newborn (n/b) rats, the number of myofibrils (MF) in the contractile apparatus of the cardiomyocytic (CMC) does not exceed 12-13 pieces. In the CMC of 45-day-old animals, this figure is 80 pieces. If we take the thrust of one CMC of newborn rats, for one conventional unit Fcmc (n/b) = 1conditional unit (c.u.). The thrust of one CMC of 45-dayold rats will be equal to Fcmc = (80 MF: 12 MF) ≈ 6.5 c.u. conditional unit. Thus, the total thrust of all CMC (Ncmc = 0.72 x 107 ) in the myocardium of newborn rats theoretically is ∑Fcmc = 0.72 x 107 c.u. The traction force of all CMC (Ncmc = 1.56 x 107 ) in the myocardium of 45 day-old rats will be: ∑Fcmc = 1.56 x 107 х 6.5 c.u ≈ 108 c.u In the time interval (n/b) – 45 days, there is a fluctuation of digital values of the cross-sectional area of the MF in the narrow range SØmf ϵ[0.65-1.05] μm2 . “Increase ↔ decrease” of the volume of sarcomeres in the MF occurs as result of fluctuations in the composition of each sarcomere of the number of structural elements – hundreds. In the center of the honeycomb is one thick, and around the perimeter of 12 thin filaments. Six thin filaments area ttached to the Z-disk on one side of the thick filament, the other six to the Z-disk on the other side of the thick filament. The area of one cell is 6,225 х 10-4 μm2 . During the period of postnatal maturation of the CMC (45 days), the number of cells in the sarcomere ranges from 1044 to 1690. Thus, in the time interval (n/r – 45) days of postnatal maturation of the CMC, the increase in the absolute volume of the contractile apparatus of the CMC occurs under the influence of the following intracellular mechanisms. 1. Increasing the length of myofibrils in 3.2 times from 25 μm to 81 μm. 2. Increasing the number of MF in the contractile apparatus of cardiomyocytes in ≈ 6.5 times from 12-13 pieces to 80 pieces. 3. Fluctuations in the cross-sectional area of myofibrils in the range [0,65-1,05] μm2 . 4. Neoplasms of honeycombs – structural and functional units in the sarcomere from 1044 to 1690 pieces. As a result of increasing the number of CMC in ≈ 2.17 times and the number of myofibrils in each CMC in ≈ 6.7 times there is an increase in the contractile force of myocardial traction in 14 times.

Within 45 days in the 2nd-CMC there is a continuous increase in the absolute (Vma), relative (Vvma) MA volumes, the total surface area ƩSnmm and the average volume of one MX (∆Vmt). The graphs of the growth of Vma, ƩSnmm and ∆Vmt values have the form of an S-like curve, which indicates the presence of three consecutive periods of monotonic development of MA and its components. In the process of postnatal morphogenesis of MA in the 2n-CMC, the biological law “division ↔ fusion” is realized. The essence of the law is that the ontogenetic regulation of the MT number in the 2n-CMC is carried out by two biological mechanisms: the division of MT, which leads to an increase in the number of organelles in the CMC, and the fusion of MT, as a result of which the number of organelles decreases, but the volume of each MT increases. The expediency of “fusion ↔ division” of MC in the process of ontogenesis of CMC is as follows. During division, the number of MT increases and, at the same time, the number of copies of mt-DNA in 2n-CMC increases. Intensive division of MC occurs in the time interval (n / p -15) days. When MT fusion occurs, duplication of mt-DNA copies occurs in each MT, which was formed after the fusion of two previous organelles. The doubled content of mx-DNA in MT 2n-CMC correlates with an increase in the number of cristae in these organelles and the area of NMM. The fusion of MT is observed in the time interval (15-30) days. This is a period of intensive growth of MA 2n-CMC, which coincides with the third period of doubling the body weight of white rats and the activation of their motor activity.

In the work were used: 15-16 and 20-21 daily embryos of rats, newborns, 1 45 daily rats Wistar males. A morphometric analysis of the myocardial parenchyma of the complex left ventricle + interventricular septum (LV + IVF) was performed. It was established that in the process of prenatal and postnatal cardiomyogenesis (15 days before and 45 days after) birth, the total number of CMC (? cmc = N1-ñ 1st cmc + N2-ñ cmc) in the parenchyma (LV + IVF) increases by 4,34 times (from 0.35 to 1.52) x 107 cmc. During the period of embryonic cardiomyogenesis (15-21) days, the values of L cmc increase by 2 times (from 0.35 to 0.74) x 107 cmc. In the process of postnatal cardiomyogenesis, in the time interval (newborns 15 daily rats), the volume of values cmc also increases by 2 times (from 0.77 to 1.52) x 107 cmc. In the time interval (1545) days, the total number of cmc does not change ? cmc ? const ? (1.51 ± 0.02) x 107 cmc. During the embryonic period of cardiomyogenesis continuous proliferation of cmc occurs with a maximum speed of 3.75 x 104 cmc/h or 625 cmc/min in the myocardial parenchyma of the newborn rat pups. After birth a significant decrease in the rate of proliferative processes in the myocardial parenchyma is observed. at t > 15 days, ?N cmc/day > 0. The formation of the 2nd cmc population in the myocardium of the complex (LV + IVF) begins from the 19th day of embryogenesis in rats. In the process of cardiomyogenesis (18 days before and 15 days after) the birth of rat pups as a result of polyploidy the number of 2nd cmc in the parenchyma (LV + IVF) increases 1000 times! (from 0.00144 to 1.44) x 107 cmc. In the time interval tº (15 45) days the digital values of the index N 2cmc ? const ? 1.44 x 107 cmc. Therefore, after the completion of the postnatal period of cardiomyogenesis, the number of 2nd cmc does not change and amounts to ? 94 95% of the total number of myocytes in the myocardial parenchyma of the complex (LV + IVF). The most active polyploidy process of cmc occurs within 5 days after the birth of rat pups. The maximum speed of polyploidy of cmc is determined on the 5th day and is equal to 73 x 103 cmc/h or 1215 cmc/min.

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The work is devoted to investigations of laser welding of rolled metal of a medical functional Ti-Ni system alloy. On the basis of the analysis of literary sources and the results of own investigations of the influence of laser welding parameters on functional characteristics of Ti-Ni shape memory alloy, the challenging directions of the further investigations are established. According to the results of the investigations of welds microstructure, concentration dependence of absolute values of recovery deformation during measurement of the shape memory effect, and investigations of phase transitions, it is established that the processes, occurring in welding zone, affect not only the strength of a joint, but also the parameters of martensitic transformation. As established, due to laser radiation and subsequent recrystallization of material in the weld area, the feasibility of shape recovery by the material of the weld body is saved, but characteristic temperatures of direct and reverse martensitic transformations grow up. The direct martensitic transformation in the region of welded joints is observed in the temperature range from 45°С to 20°С. Shape recovery in material of welded joints is observed at temperature range of 60-100°С. The obtained results allow determining the ranges of values in which it is expedient to optimize the parameters of laser treatment modes. [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry and X-ray diffraction were employed to study the effect of intense mechanical treatment on the surface chemical state, composition and structure of a commercial biomedical CoCrMo alloy ('Bondi-Loy'). The ultrasonic impact treatment of the alloy in air with duration up to 30 s was found to cause the deformation-enhanced oxidation and deformation-induced surface segregation of the components and impurities from the bulk. The compositionally inhomogeneous mixed oxide layer formed under impact treatment was composed mainly of Cr2O3 and silicon oxide with admixture of CoO, MoO2, MoO3 and iron oxide/hydroxide, the latter being transferred onto the alloy surface from the steel pin. The impact treatment promoted a progressive accumulation of carbon on the alloy surface due to its deformation-induced segregation from the bulk and deformation-induced uptake of hydrocarbons from the ambient; concurrently, the dissolution/refinement of carbides originally present in the as-cast CoCrMo alloy occurred. The impact treatment gave rise to a two-fold increase in the volume fraction of the martensitic hcp ε-phase, a 30% increase in the surface microhardness and improved resistance to corrosion in the solution of artificial saliva compared to the as-polished alloy. [ABSTRACT FROM AUTHOR]

In order to design materials having different mechanical properties combined with a permittivity of 2.2-2.6 and tg δ=2·10-4.10 at 20±1° C and 10 Hz, it is possible to use compositions consisting of polystyrene, polyisobutylene and polyethylene. Projections of the three-dimensional triangular composition-property diagrams are presented for selecting the composition corresponding to spcified properties (hardness at 20 and 50° C and breaking stress and elongation). [ABSTRACT FROM AUTHOR]

Background: Two recent meta-analyses have suggested the association between digit ratio (2D:4D) and aggression is weak. This conclusion has been criticised because the meta-analyses conflate forms of aggression that show strong sex differences with those that do not, and most studies have considered post-pubertal participants.Aims: We test the influence of 2D:4D and ethnicity in the expression of aggression in children and adolescents in four ethnic groups of European and African origin.Study Design: Buss and Perry aggression questionnaire. Direct measurement of the 2nd and 4th digits.Subjects: 1296 children and adolescents from Tanzania and Russia from 4 ethnic groups - Datoga, Meru, Russians, Tatars.Results: There were ethnic and gender differences in ratings on aggression with boys consistently reporting more physical aggression. In all four samples right 2D:4D was significantly lower in boys, compared to girls. With regard to our total sample of boys, the right 2D:4D was significantly and negatively associated with self-ratings on physical aggression, but no association was found for left 2D:4D. No associations between 2D:4D and physical aggression were found for girls. Hostility was negatively correlated with 2D:4D for boys, and anger was positively correlated with 2D:4D in girls.Conclusion: Sex differences were strongest for right 2D:4D (boysgirls). Right 2D:4D was negatively related to physical aggression in boys only, suggesting possible relationship to prenatal androgenization. [ABSTRACT FROM AUTHOR]