Complicated wear-resistant parts made by selective laser melting (SLM) of powder material based on compositions of metal and ceramics can be widely used in mining, oil engineering, and other precision engineering industries. Ceramic–metal compositions were made using nanoscale powders by powder metallurgy methods. Optimal regimes were found for the SLM method. Chemical and phase composition, fracture toughness, and wear resistance of the obtained materials were determined. The wear rate of samples from 94 wt% tungsten carbide (WC) and 6 wt% cobalt (Co) was 1.3 times lower than that of a sample from BK6 obtained by the conventional methods. The hardness of obtained samples 2500 HV was 1.6 times higher than that of a sample from BK6 obtained by the traditional method (1550 HV). Additive manufacturing is the common name for a family of layer-by-layer production technologies using electronic CAD-models. The principle of additive manufacturing is to create functional products with the help of layer-by-layer addition of material by depositing or spraying powder and by adding a liquid polymer or composite ,2. One of the most promising technologies for additive manufacturing is the technology of selective laser melting (SLM)  because it has a number of fundamental advantages: it is waste-free, has versatility, and has the ability to manufacture high-precision complex parts that are not inferior, and which are sometimes even superior in their physicomechanical characteristics than the parts obtained by traditional shaping. This technology can reduce the manufacturing time and cost of complex parts in single and small batch production due to the lack of a stage for creating a special tool and a reduction in the number of technological stages ,4,5,6.Selective laser melting uses a wide range of materials. Using such materials as aluminum alloys, corrosion-resistant steels, and cobalt-based alloys it is possible to obtain a high complexity of physicomechanical properties of products made by the SLM method ,10,11,12When applying SLM to brittle materials, the part often cracks already in the manufacturing process. Significant temperature gradients occur during laser heating. Inhomogeneous thermal fields and thermal expansions generate thermomechanical stresses. Stresses can exceed the mechanical strength of the material, so the material processed by the laser should be resistant to the thermal shocks. Up to now, there have been no successful attempts to manufacture parts from ceramic materials comparable in mechanical properties to parts obtained by classical technology. However, the interest in SLM for ceramics is quite high ,14,15.One of the promising materials is metal-based composite materials with the addition of ceramic inclusions. Hard alloys are a classic example of cermet materials, which are well studied and widely used. Hard alloys are based on a matrix of alloys of elements of the iron group hardened by carbides of refractory metals ,18,19,20Immediately after the advent of SLM technology, interest arose in obtaining by this method compositions with a metal matrix. For example, Laoui et al. in 1999 studied the WC–Co system , and XiaFurther, the list of tested composite materials for SLM expanded; however, the obtained materials were of unsatisfactory quality.Examples of use of composite materials with a metal matrix are described in the literature more often for laser surfacing than for SLM. In laser surfacing, the distribution of temperature and cooling rates are similar to those for SLM; therefore, they require consideration. In , coatingThus, the authors concluded that when manufacturing composite materials by laser welding, it is important to obtain a plastic matrix so that the material does not crack.Titanium carbide is also widely used as a hardening phase in laser surfacing. Its density is about four times lower than that of tungsten carbide, which is essential for use in the aerospace industry. Candel et al.  obtainedA promising direction for improving the mechanical properties of carbides is reducing the grain size . For thi6 K/s, specific for this process, often provide a fine-grained submicron or nanoscale structure with increased strength and wear resistance. Complicated parts made by SLM of powder material based on compositions of metal and ceramics can be widely used in mining, oil engineering and other precision engineering industries. Therefore, the technology of manufacturing from metal powder compositions by selective laser melting is an important scientific and technological task.SLM is not fundamentally limited by the complexity of the geometric shape and refractoriness of the material. Moreover, high cooling rates of the order of 10The aim of this work is researching and developing wear-resistant ceramic–metal compositions of the WC–Co system obtained by SLM using nanosized powders.As an experimental material for selective laser melting, the WC–Co system was chosen. To obtain powders of composite materials, we used cobalt metal powder and ceramic powder of tungsten carbide: nanoscale and micron powders of cobalt and WC. The substrates were carbide plates of grade BK20 GOST 19106-73 , production, Russia, Kirovgrad, Kirovgrad hard alloy plant.The powders were investigated using particle size analysis on OCCHIO 500 nano measuring equipment  and using a Tescan Vega 3LMH scanning electron microscope with an EDS detector . The preparation of the powder composite material was carried out by mechanical alloying in a Retch PM 100 planetary ball mill .Production of experimental samples was carried out on a special laboratory machine for selective laser melting—an ALAM (advanced laser additive machine)—that was developed and assembled at MSTU “STANKIN” (Moscow. Russia). The SLM process diagram is shown in The processing regimes were determined in several stages. The technique for achieving optimal regimes are described in detail in previous publications ,19,20.The main stages were: initial assessment of the optimal set of parameters using mathematical modeling; determination of processing modes in the manufacture of single tracks; definition of processing modes in the manufacture of single layers; and definition of processing modes in the manufacture of volumetric objects.This method allows the exclusion of unsatisfactory modes and moving on to the next steps. Each step allows one to define a group of parameters for the objects: single tracks ; single layers (hatch spacing); and volumetric objects (scanning strategy).The powder layer thickness ranged from 10 to 100 μm. The powder layers were scanned by a laser beam with a wavelength of 1.07 μm, with a laser spot diameter of about 100 μm. The laser beam power varied from 30 to 180 W; the scanning speed was from 30 to 350 mm/s.In previous works ,18, it wMetallographic analysis of the obtained samples was carried out using optical and electron microscopy. The chemical composition was determined by energy dispersive X-ray spectroscopy using a Tescan VEGA 3 LMH scanning electron microscope . Diffraction spectra were obtained on a PANalytical Empyrean Series 2 X-ray diffractometer using CoKα radiation. The analysis of the phase identification was carried out using PANalytical High Score Plus software  and the ICCD PDF-2 database. The experiments to determine wear resistance under abrasive conditions were carried out on a Calowear Anton Paar machine.  The counterbody was a hardened steel ball with a diameter d = 25.4 mm. An abrasive suspension was fed into the contact zone between the ball and the sample surface. We used 2 types of suspensions based on silicon carbide with a particle size of 2–5 μm and a diamond suspension with a crystal size of 9 μm. To determine the hardness of the samples, a Qness Q10A microhardness tester  was used. The fracture toughness coefficient was measured according to the method proposed in When preparing the initial mixtures to obtain high wear resistance, we proceeded from the possibility of creating a mixture with a maximum amount of micron tungsten carbide provided that it was uniformly distributed in a nanostructured cobalt binder.coS should be greater than or equal to the surface area of the tungsten carbide powder wcS for homogeneous coating by nanocobalt particles of tungsten carbide.In preparing the initial mixtures for obtaining high strength properties, we proceeded from the possibility of creating a mixture with the maximum amount of tungsten carbide. When preparing powder mixtures of micron tungsten carbide and nanocobalt, it is necessary to take into account the surface areas of the powders. The surface area of the cobalt powder To determine the area of the components in a mixture of WC and Co, the shape of the powder particles was taken as a perfectly round ball. Then the surface area of one particle is equal to:WCr = 400 nm and an average radius of the cobalt particle Cor = 40 nm, the area of one particle particleCoS = 20,096 nm2 and particlewcS = 2,009,600 nm2. They are related as 1/100. Therefore, for homogeneous dusting of one WC particle, 100 particles of Co are needed. Knowing the volume and density of the chemical component, it is possible to find the mass of one particle:V is the volume of one particle:With an average radius of the tungsten carbide particle particle CoM = 2,384,725.63 × 10−27 g, and the mass of the tungsten carbide particle particle WCM = 4,233,557,333.86 × 10−27 g. Therefore, in 100 grams of the 94 wt% WC and 6 wt% Co composition, one can determine the number of particles n:Thus, the mass of one particle of cobalt powder Con = 2.5 × 1021, and the number of tungsten carbide particles is WCn = 2.2 × 1019. Then the surface area of one component of the mixture componentS is equal to:The number of cobalt particles is CoS = 50,240 × 103 m2 is greater than the surface area of the tungsten carbide powder WCS = 44,211.2 × 103 m2.The above estimates indicate that in 100 grams of the composition, 94 wt% WC and 6 wt% Co, the surface area of the cobalt powder The powder is highly agglomerated, which is a consequence of its submicron size. The distribution of chemical elements is heterogeneous because cobalt nanopowder is agglomerated a.In this regard, the powder mixture was processed in a ball mill. After processing, the powder mixture was also studied using SEM; as a result it was revealed that the treatment made it possible to achieve a homogeneous distribution of elements and break up the agglomerates b,c.The investigated characteristics of the resulting powder mixture are summarized in A histogram of the particle size distribution of the powder is shown in The measured average dimension for WC and Co was 800 nm and 80 nm, respectively c. The stWe studied samples obtained by SLM using the ALAM laboratory machine: single tracks, single layers, and volume cubes. Samples were obtained by varying the process parameters: powder layer thickness (H), laser radiation power (P), scanning speed (V), and hatch spacing (s).Based on the studies described above, a mixture with the maximum possible amount of tungsten carbide was selected under the condition of homogenous coating of micron tungsten carbide by nanocobalt: 94 wt% WC and 6 wt% Co.A single track is an elementary unit in the method of selective laser melting. The SLM process can be considered as a complex of tracks for forming a layer and a complex of layers for forming a volumetric object. Therefore, the parameters were found, at which stable tracks were obtained. It will be rational parameters for obtaining a single layer.The search for modes for obtaining stable single tracks was carried out according to three parameters: the powder layer thickness, the power of the laser, and the scanning speed. The range of variable parameters is indicated in the "Materials and Methods" section. Metallographic analysis of the cross section of the tracks showed that with the decreasing in the thickness of the applied layer, the geometry of the cross section of the track was more correct, while with a high parameter of the thickness of the layer, the track had a relief surface with metal growths at the borders. A thickness of 20 mm was chosen as the rational value of the thickness of the applied layer because applying a thinner layer is mechanically difficult by the leveling system of the machine, and the increased thickness requires more laser power or lower scanning speed, which leads to overheating and subsequent cracking. Varying the scanning speed at a constant power of 70 W showed that with an increase in speed, the heterogeneity of the structure decreased, and the geometry of the track became more stable . In addition, increasing the scanning speed reduced the overheating of the material, reduced the probability of cracking, and increased productivity, but at speeds above 300 mm/s, the track did not have strong contact with the substrate.Varying the laser power in the above ranges showed that the increase in power from 70 W to 150 W led to a significant decrease in the height of the track, which is explained by the evaporation of the material. It was experimentally revealed that the height of the track at a power of 150 W (V = 300 mm/s) was 4 times less than at a power of 70 W. At a power of less than 50 watts, the track had an islet shape and sometimes did not have contact with the substrate, which indicated insufficient energy to transfer material. In addition, an increase in power above 70 W led to the appearance of microcracks on the surface of the tracks , which wRational regimes were established for a mixture of 94 wt% WC and 6 wt% Co: scanning speed—300 mm/s, powder layer thickness—20 μm, laser power—50–70 W.Fusion of a mixture of 94 wt% WC and 6 wt% Co with a high content of hardening carbide phase gave homogeneous formed tracks with strong metallurgical contact with the substrate .This result was explained by the structure of the powder. Nanosized cobalt powder has an extended surface and, as a result, the melting temperature was lower than that of the micron powder, which made it possible to obtain a melting pool with a homogeneous distribution of unmelted WC micron particles.For further studies of the structure and properties, volumetric samples were made according to the above optimal regimes.We studied cross sections on an SEM. According to energy dispersive microanalysis, the quantitative and qualitative composition of the fused samples corresponded to the initial powder compositions. The research results are shown below in Metallographic studies confirmed that the obtained samples from WC–Co powder mixtures with a content of 94% Co formed a metallurgical contact with the substrate, and the distribution of chemical elements over the cross section was homogeneous. In general, compositional heterogeneities in the fused samples were much smaller than in the substrate. The scale of heterogeneity in the material obtained by the SLM was less than the resolution limit of the energy dispersive analysis used, which was about 1 μm. Therefore, we can say that the resulting material was homogeneous at a submicron level.2C and WC. According to semi-quantitative analysis, the phase ratio was 90% W2C/7% WC; the rest was a cobalt-based solid solution. The X-ray diffraction pattern of this sample is shown in X-ray diffraction analysis of the fused powder mixture of 94 wt% WC and 6 wt% Co showed that the sample contained the main phases of W2C, which has a higher hardness than WC, prevailed in this composition, which suggested a high hardness of the material [2C material is two times higher than that of WC. Carbide Wmaterial . It was material  that theA study of the influence of the percentage composition and size of WC fractions on the formation of cracks in parts made by SLM shows that when SLM is applied to brittle materials, the part often cracks already in the manufacturing process. In all cases, the fraction of the hardening phase without cracking in the metal matrix did not exceed 10%. This is not always enough to obtain the necessary mechanical properties. Attempts to increase the content of the hardening phase often lead to cracking of the material during SLM. The mixtures with different contents of WC were studied: 25%, 50%, and 94%.For example, the composition of 50 wt% WC and 50 wt% Co (micron fraction of Co) without cracks in the manufacture of single tracks and single layers, cracked in the manufacture of a cube sample. Cracks formed on the surface of the layer and in the cross section of the material . Based on the experimental data, the accumulated experience on the SLM was confirmed—an increase in the content of the hardening phase led to cracking of the material. However, a composition containing 94% WC and 6% Co nanopowder was an exception to this statement; cracks were not observed either in single tracks, single layers, or in multilayer samples . Comparative tests on the wear resistance and hardness of a cube sample obtained by the SLM from a powder mixture of WC–Co 94%–6% showed that when using silicon carbide SiC as an abrasive, a recess did not form on the sample, which indicated a high hardness of the sample.0.05 to 1550 HV0.05, respectively. The values of the wear rate and microhardness are given in Tests for a sample of 94 wt% WC and 6 wt% Co were repeated with a diamond abrasive. To compare the coefficient of wear rate of the material, 94 wt% WC and 6 wt% Co, and carbide plates BK6 and BK20 obtained by conventional sintering were selected. The wear rate of the samples with a ratio of components of 94 wt% of WC and 6 wt% of Co was 1.3 times lower than that of a sample of BK6 obtained by the traditional method, with hardness 2500 HV1/2 and 3.4 MPa∙m1/2, respectively, which, given the high hardness, is a good result.Fracture toughness tests were carried out on polished samples. The average crack resistance coefficients were calculated from three prints on each sample . The res0.87, W0.13) (3%). Due to the increased surface area, nanocobalt powder has a melting point lower than that of micron powder, which makes it possible to obtain a liquid melt pool with a homogeneous distribution of unmelted micron particles WC. The hardness of the obtained samples containing 94 wt% WC and 6 wt% Co is 2500 HV. The wear rate of the obtained samples is 1.3 times lower than that of a sample from BK6 obtained by the conventional method. The developed process parameters can be recommended for the manufacture of complex parts working in increased abrasive wear conditions.Selective laser melting of metal-powder compositions of the WC–Co system was studied using nanosized powder of Co. The wear-resistant cermet material was obtained with a ratio of components: 94 wt% of WC and 6 wt% of Co. The rational conditions for the SLM were determined, which provided high hardness and wear resistance of the ceramic–metal composition. The structure of the obtained material consists of tungsten carbides W2C (90%), WC (7%), and FCC (face-centered cubic) solid solution based on cubic high temperature modification α-Co (CoRU2669034C1. The method of obtaining products from powder material 94WC6Co.RU2669135C1. The method of manufacturing products by selective laser melting of a powder composition WC–Co.As a result of work, 2 patents were obtained:


Meiosis, the type of cell division that halves the chromosome number, shows a considerable degree of diversity among species. Unraveling molecular mechanisms of the meiotic machinery has been mainly based on meiotic mutants, where the effects of a change were assessed on chromosomes of the particular species. An alternative approach is to study the meiotic behavior of the chromosomes introgressed into different genetic backgrounds. As an allohexaploid, common wheat tolerates introgression of chromosomes from related species, such as rye. The behavior of individual pairs of rye homologues added to wheat has been monitored in meiotic prophase I and metaphase I. Chromosome 4R increased its length in early prophase I much more than other chromosomes studied, implying chromosome specific patterns of chromatin organization. Chromosome conformation affected clustering of telomeres but not their dispersion. Telomeres of the short arm of submetacentric chromosomes 4R, 5R, and 6R failed more often to be included in the telomere cluster either than the telomeres of the long arms or telomeres of metacentrics such as 2R, 3R, and 7R. The disturbed migration of the telomeres of 5RS and 6RS was associated with failure of synapsis and chiasma formation. However, despite the failed convergence of its telomere, the 4RS arm developed normal synapsis, perhaps because the strong increase of its length in early prophase I facilitated homologous encounters in intercalary regions. Surprisingly, chiasma frequencies in both arms of 4R were reduced. Similarly, the short arm of metacentric chromosome 2R often failed to form chiasmata despite normal synapsis. Chromosomes 1R, 3R, and 7R showed a regular meiotic behavior. These observations are discussed in the context of the behavior that these chromosomes show in rye itself. Bivalents formed during meiotic prophase I are essential to halve the chromosome number. Bivalent formation requires that homologous chromosomes, mainly located in separate nuclear territories in premeiotic interphase nuclei , move toArabidopsis and PAIR2-PAIR3 in rice (A programed production of double-strand DNA breaks (DSBs) catalyzed by Spo11 in conjunction with other proteins triggers the initiation of chromosome interactions . DSBs ar in rice . The ide in rice . Then, h in rice . The SC  in rice . The gen in rice . The SC Drosophila melanogaster females and in Caenorhabditis elegans, pairing and synapsis can occur independently of recombination  females both with achiasmate meiosis, show well-aligned bivalents at metaphase I. The presence of the SC until anaphase I provides the physical connection between homologues in B. mori females . A handful of complete sets of wheat-rye additions are available  as an allohexaploid, tolerates the addition of chromosomes from related species such as rye, vailable . These lin situ hybridization (FISH) making possible to identify the position of the adjacent telomere in the meiotic bouquet  chromatin remodeling (ii) the telomere movement leading to the formation of the bouquet and its resolution; (iii) the effect of telomere positioning at the bouquet on synapsis and chiasma formation.S. cereale, 2n = 14) introgressed in hexaploid wheat T. aestivum, were used. The wheat-2R, wheat-3R, wheat-4R, wheat-5R, wheat-6R, and wheat-7R lines are disomic additions of the Imperial rye chromosome in a Chinese Spring wheat background . This remnant folding of chromatin made it difficult to trace and measure the complete chromosome length. The assessment of chromatin reorganization in each rye chromosome was based on the variation of its length in completely synapsed bivalents at pachytene relative to that in mitotic metaphase. Figure 2 compares the karyotype of rye chromosomes in both types of cells. In addition to the chromosome length, karyotypes show the position of the centromere and heterochromatin chromomeres. The two arms of all rye chromosomes show a distinctive pattern of heterochromatin markers. Chromosomes 4R and 5R bear a subtelomeric chromomere only in the short arm, the 4RL arm shows no marker and the subdistal chromomere of 5RL is smaller than that of 5RS. The subtelomeric chromomeres of the short and long arms of chromosomes 1R, 2R, 3R, 6R, and 7R differ in the heterochromatin contain. In addition to the subtelomeric marker, the arms 1RL, 2RS, 2RL, 6RL, and 7RL carry one or two intercalary chromomeres. Values of chromosome length and centromere index (100 × short arm length/chromosome length) are given in Table 1. The length of mitotic chromosomes ranges between 12.9 and 16.4 μm with an average of 15.1 μm. Bivalents at pachytene of chromosomes 1R, 2R, 3R, 5R, 6R, and 7R reached a length that ranges between six and seven times the size of the mitotic chromosome. Surprisingly, chromosome 4R is 11.2 times longer in pachytene than in mitotic metaphase. This result supports a different reorganization pattern of rye chromatin in leptotene in the wheat-4R addition relative to the others.Concomitant with the bouquet organization, chromatin undergoes a remodeling process that reduces its packaging level and causes a large elongation of chromosomes. At the bouquet, decondensation of rye chromatin was apparent but a considerable folding degree was still observed . In all of these cases the homologous chromosome ends are intimately associated denoting the initiation of synapsis. The telomere of one chromosome arm 3RS, one chromosome arm 6RS and the two arms 4RS are not included in the telomere cluster in nuclei of Figures 3C,E,F, respectively. From the number of cells with zero, one or two homologous ends included in the telomere pole it was possible to estimate the probability of incorporation to the telomere cluster of the telomere of the seven short chromosome arms and the long arms 1RL, 2RL, 3RL, 6RL, and 7RL. This probability appears diagrammed in Figure 4. The telomere of both arms of metacentric chromosomes 2R, 3R, and 7R as well as the telomere of 1RL and 6RL migrated to the telomere pole in almost all cells. However, the telomere of the short arm of submetacentric chromosomes 4R, 5R, and 6R failed in its incorporation to the telomere pole in more than 25% of the meiocytes. On average, such telomeres were separated 10 μm from the telomere cluster. Accordingly, the probability of incorporation of the telomere of the short arm of the seven rye chromosomes and the centromere index were positively correlated . This result supports an effect of chromosome conformation in the positioning of telomeres during the organization of the bouquet. Although the centromere index of 1R identifies this chromosome as submetacentric, the location of the nucleolar organizing region on 1RS probably represents an additional factor conditioning its arrangement in leptotene. Consistent with the disturbed positioning of the telomeres of 4RS, 5RS, and 6RS is the reduction in the frequency of association of their subtelomeric markers in cells with the two homologous ends included in the telomere cluster. While the subtelomeric chromomeres of 4RS, 5RS, and 6RS were intimately associated on average in 46% of the cells studied, the homologous ends of metacentric chromosomes were in 86%.The position of the telomere of the short arm of all rye chromosomes and of the long arms 1RL, 2RL, 3RL, 6RL, and 7RL in PMCs at early prophase I was identified by its close proximity to the adjacent subtelomeric heterochromatin marker. FISH analysis combining the telomeric and the rye-specific heterochromatin DNA probes in nuclei at the bouquet stage revealed whether rye telomeres were included in the telomere cluster or not. Figure 5 shows nuclei with the chromosomal ends of the rye bivalent relatively close or occupying diametrically opposed positions, respectively. The mean distance between the ends of each chromosome, as well as the size of the nuclear diameter, appear indicated in Table 2. The ends of metacentric chromosome 3R and submetacentric chromosomes 4R and 5R, show very similar separation and the same happens in the group formed by metacentric chromosomes 2R and 7R and submetacentric chromosome 6R. There is no significant correlation between the inter-chromosome ends distance and the centromeric index . Thus, chromosome conformation does not affect the telomere movement during the bouquet dissolution. Between chromosomes variation in the degree of separation of the two ends was correlated to the size of the nuclear diameter . Such a variation should at least in part be a result of manipulation during the realization of preparations. In fact, with the exception of chromosome 3R, the between ends distance/nuclear diameter ratio was similar in all remaining chromosomes. The telomere dispersion produced in zygotene separated the chromosomal ends to nuclear positions distant on average 43% of the nuclear diameter.The fact that telomere clustering was chromosome conformation dependent led to verify whether the dispersive telomere movement responsible of the bouquet disorganization was also affected by chromosome conformation or not. When both ends of rye chromosome pairs 1R, 2R, 3R, 6R, or 7R were included in the telomere cluster, they were situated at an average distance of 2 mμ. Such a distance is expected to increase because of telomere dispersion during zygotene. Thus, the spatial separation between the ends of each bivalent in nuclei at pachytene, in which the bouquet is completely disorganized, should provide an assessment of the effect of the dispersive telomere movement. The distance between the chromosome ends was scored in completely synapsed bivalents. A great between cells variation was found. Figures 2C,E, 5A,B), however, unmatched chromosome arms were also observed . Failure of synapsis in the distal half varied between chromosomes arms . Chromosome arms 5RS and 6RS, with disturbed telomere migration during leptotene, showed the lowest level of synapsis. Chromosome arm 4RS, despite restricted telomere migration, completed synapsis in most PMCs. Because synapsis progresses from the end to the center of the chromosomes (Table 3).In many plant species crossovers are non-random distributed along the chromosomes. In wheat, barley and rye, they are confined to the distal half of each chromosome arm . Such reomosomes , unsynapFigure 7). Two homologous arms bound at metaphase I had formed at least one chiasmata, but it is difficult to establish whether additional chiasmata were present or not. Thus, the frequency of homologous arms association at metaphase I represents an underestimation of the number of chiasmata per chromosome arm. Table 4 shows the frequency of association for the different rye chromosome arms as well as the total number of associations per cell. Both arms of chromosomes 1R, 3R, and 7R, and the long arm of chromosome 2R formed chiasmata with frequencies higher than 90%. The remaining arms showed lower frequencies, especially the arms 2RS, 4RS, 4RL, 5RS, and 6RS, whose frequencies ranged between 25 and 70%. The total number of associations varied between lines. A maximum number of 42 arm associations can be formed in the wheat-1R line and 44 in the other six lines. Thus, chiasma formation failed not only between rye chromosome arms but also between wheat chromosomes, especially in the addition lines wheat-4R and wheat-5R.Chiasmata formed by rye chromosomes were inferred from the occurrence of association between each homologous arm pair in PMCs at metaphase I (Table 4). But let us analyze separately the different steps of prophase I that precedes chiasma formation.The majority of rye chromosomes of the addition lines studied undergo a meiotic behavior that it is different from that observed in rye itself. This is apparent, if attention is paid to the number of chiasmata formed. In rye, a total of 13.4 (1.9/chromosome) chiasmate bonds are formed at metaphase I . This fiRemodeling of chromatin produced in leptotene leads to a more relaxed chromosome organization, which most likely facilitates the search of the homologous partner. During the SC assembly, the axial elements (chromosomes) become shortened. This shortening has been quantified in electron microscopic studies of spread nuclei of both rye  and wheaOne could assume that differences in length between chromosomes in pachytene might be a result of differences in their DNA content, given the large size, 8.1 Gb, of the rye genome . ChromosIt is also noteworthy that the mean length of rye chromosomes at pachytene is much higher in the addition lines, 110.9 μm, than in rye itself, 62.5 μm . The meaLittle is known about the impact of molecular interactions underlying the introgression of rye chromatin in a wheat background. A comparison of the transcriptomes of wheat, barley and a wheat-barley ditelosomic 7HL addition revealed reprograming of the transcriptomes of wheat and 7HL in the addition line . Only 3%Telomeres of the long arms 1RL, 2RL, 3RL, 6RL, and 7RL as well as telomeres of the short arm of metacentric chromosomes 2R, 3R, and 7R, were included in the telomere cluster in almost all PMCs. By contrast, the telomere of the short arm of submetacentric chromosomes 4R, 5R, and 6R showed a lower probability of inclusion in the telomere cluster. This result reinforces previous studies supporting a chromosome conformation dependence in the ability of telomeres to converge in the telomere pole . ChromosArabidobsis, SUN protein foci spread through the nuclear envelop during leptotene, cluster in the periphery of one hemisphere at the bouquet, and back to spread through all the nuclear envelop during and beyond pachytene  domain protein that interact with the chromosome ends  and the achytene . This SUAnother explanation of the behavior of telomeres of 4RS, 5RS, and 6RS is that they have to cover longer distances than other telomeres to reach the telomere pole during the bouquet organization. This explanation is based under the assumption that the site of the telomere pole is most likely installed in the region of the telomeric hemisphere with the highest density of telomeres, that is, in the region where telomeres of long arms are located. In such a situation, telomeres of metacentric chromosomes can be equidistant relative to the telomere pole, while telomeres of the short arms of submetacentric chromosomes lay farther away of this pole. In support of this assumption are two facts: (i) telomeres of the long arms are included in the telomere cluster in almost all cells, (ii) the centromeric end of telocentric chromosomes fails also in its incorporation to the telomere pole . The telThe effect of chromosome conformation on telomere clustering is not extended to the movement produced during zygotene, which disperses telomeres through all the nuclear periphery. Telomeres of any chromosome pair are very close at the bouquet and their separation seems to be at random, i.e., without any programed itinerary. Within lines variation of the distance between the ends of the rye bivalent at pachytene agrees with a random dispersion of telomeres. Most likely, the overall arrangement of bivalents in the nucleus and the simultaneous movement of all chromosomes should condition severely the distance covered by each telomere.Table 2). However, the frequency 92% of association of chromosome arm 7RS at metaphase I suggests an almost normal level of synapsis in the anther where metaphase I was studied.Restriction of chiasma formation to the distal half of chromosome arms in species such as wheat, rye or barley  implies Table 4) and is the consequence of the synapsis failure that such arms showed at pachytene. However, other arms with normal synapsis suffered a considerable reduction of the chiasma frequency. This was the case of the arms 2RS, 4RS, and 4RL. The wheat-4R addition line showed the lowest number of chiasmate bonds, 37.9, which is far from 44, the expected maximum number. Environmental variation could explain minor differences between lines, but the low chiasma frequency observed in the wheat-4R addition suggests a negative effect of the genetic background of this line on chiasma formation, which affects both wheat and rye chromosomes. Addition of individual chromosomes of rye to wheat produce changes in traits such as spike and spikelet morphology (Chiasma distribution in rye chromosomes of wheat-rye addition lines was earlier studied . Howeverrphology . Additiorphology . It is prphology .TN designed and conducted the research and wrote the work.The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


As the population ages, many more people will be in need of long-term care. According to a recent report by Alzheimer's Disease International and the Karolinska Institute, 84% of people with dementia are cared for at home and 16% in nursing homes. Several Web-based interventions have been developed to assist the work of carers at home. Measuring the levels of electronic health  literacy is of top priority to facilitate inclusion of this population and develop training programs to enhance eHealth literacy skills.This study aimed to adapt the eHealth Literacy Scale  for carers of people with dementia, who speak Greek as their native language and live in Greece and Cyprus, and to test the reliability and validity of the scale for carers.The content validity of the eHealth Literacy Scale for Carers of People With Chronic Diseases  was assessed with an expert panel (N=10). A descriptive study with face-to-face interviews among 101 primary carers of people with dementia was conducted. In addition to the eHeals-Carer to assess their perceived eHealth literacy, participants responded to a brief questionnaire regarding characteristics of internet use and provided sociodemographic data. The internal consistency of the tool and the construct validity via an exploratory factor analysis (EFA) were explored.The Mean Item-Level Content Validity Index (CVI) and Scale-Level CVI Average was 0.93. The participants were mostly women , aged less than 60 years  with secondary education. The internal consistency was estimated at a Cronbach alpha of .83. Two factors were extracted from the EFA: information seeking questions 1 to 5 (factor 1) and evaluation questions 6 to 8 (factor 2).eHeals-Carer is the first perceived eHealth literacy tool adapted for carers of people with dementia. The use of Web-based services available for carers could help them and improve the health care system in the long term. In Greece and Cyprus, there is a lack of services, and improving the digital skills of carers could provide them with the means to support themselves at home and improve care provision.RR2-10.2196/resprot.8080 As the population ages, old age diseases are on the rise, that is, many more people will be in need of long-term care in the years to come. In many countries, family and friends usually undertake the role of the carer filling the gap from the lack of organized health and social services, a phenomenon that is more common in Mediterranean and Eastern European regions .According to a recent report by Alzheimer's Disease International and the Karolinska Institute, 84% of people with dementia are cared for at home and 16% in nursing homes . Most caSeveral Web-based interventions have been developed to assist the work of carers at home. They are easy to use and provide quick access to disease-specific information, as in the case of health care websites, psychoeducational platforms, applications, and telehealth and telemonitoring devices -13. In mThere is a lack of published data on eHealth literacy level among carers of people with dementia and adapted or newly developed tools for this purpose.Norman and Skinner  developeThe need for the eHeals to be adapted for the carers population as the eHealth Literacy Scale for carer of chronic diseases , is associated with their caring needs. They usually search information for another person instead of for themselves and their personal health issues, and they are more receptive to technologies that assist them in their caregiving ,34. AdapAt the moment, we may only find information on the style of health-related internet use and possible predictors of this type of use made by carers ,36.Internet in Cyprus report, only 9.6% of the Greek Cypriots search the internet for health information on a weekly basis, and 43% of the sample has never searched the internet for health topics [In Greece, recently, a study identified older age and lower education among the main predictors of lower functional eHealth literacy in a Greek-speaking population . We knowh topics .The aim of the study was 2-fold: (1) to identify available validated eHeals as part of a scoping review and (2) to evaluate the validity and reliability of the proposed eHeals for carers among a sample of Greek-speaking carers of people with dementia in Greece and Cyprus.As part of the validation process, we have searched following the methodology of a scoping review as described in the studies by Arksey and O’Malley and Peters et al ,40 for rThe main research questions of the review are as follows: (1) What type of statistical analysis is used to extract factors for eHeals? (2) How the Web 2.0 problem is handled in existing validations of eHeals? (3) Is there any difference in rating the scale? and (4) Is any eHeals validation for carers available?We searched for all validations of eHeals in relevant databases  and gray literature (eScholarship) until December 2018. Keywords used were eHeals and eHealth Literacy Scale.The studies assessed are based on the following inclusion criteria: (1) the study should be related to the topic of eHealth literacy; (2) the study should be related to the scale reliability and validation; and (3) the study should be published in EnglishWe did not include studies that used eHeals as a measure of eHealth literacy, but no information on validation was provided. The flowchart and related table of results are included in this paper as Following the literature review, we designed the validation and adaptation of the eHeals among Greek and Cypriot carers of people with dementia. Permission to use and adaptation of the scale were obtained by the authors . The stuAs part of the first step, we proceeded with the double forward and backward translation between the original English and Greek. Initially, 2 independent translators, both native speakers of Greek and fluent in English translated the scale into Greek. After comparing and merging the 2 translations into a single Greek translation by consensus, 2 independent back translations into English were derived by an additional set of 2 bilingual translators, 1 care professional and 1 researcher . In case of disagreement, we employed consensus meeting among the research team members based on expert opinion and existing literature.In the second step, face validity by the research team followed. During this phase, researchers assessed the available Greek translation of eHeals and if the translated items corresponded to the English version of eHeals. The research team selected the final version in the Greek language and adapted it accordingly by adding a reference to the caregiving concept in every item of the scale. All items were modified accordingly to refer to the health and caregiving issues of a friend/relative, as, for example, in item 1: “I know what health resources are available” adapted to item 1: “I know what resources/information are available on the Internet concerning the health and caregiving issues of my friend/relative.” The caregiving issues on the scale are explained as the practical, financial, legal issues and information about the disease and available services. In the case of items 2, 3, and 4, we also added short clarification to facilitate understanding. Modifications of the scale are available in The content validity of the adapted items in the Greek language was assessed by a panel of experts in the field of eHealth and dementia or older people. Following this process, the questionnaire was piloted in 25 carers. Finally, the internal consistency of the final version of the Greek-adapted scale was tested among a sample of primary carers, and construct validity was followed with exploratory factor analysis (EFA).To proceed with the content validity index, we invited 10 experts to reply to the content validity of the questionnaire. The experts were invited because of their work on eHealth and/or dementia domain. Of 10 experts, 8 were health professionals: 3 health care professionals, nurses, and psychologists working in the field of technology , 1 member of the Greek team of the European Health Literacy Survey, and 4 health care professionals working in dementia care. The remaining 2 were information technology experts working in the field of eHealth.The data collection of primary carers was made in the framework of the research protocol for “the Association of Health Literacy and Electronic Heath Literacy with Self-Efficacy, Coping and Caregiving Perceptions Among Carers of People with Dementia: Research Protocol for a Descriptive Correlational Study” .The final sample of the protocol was estimated with 95% power and a type 1 error of 5% to 168 primary carers. All questionnaires were pilot tested in 25 primary carers of people with dementia .The validation of eHeals adapted for carers proceeded with a convenience sample of 101 carers from Greece and Cyprus, based on the subject-to-item ratio 10:1 -45. PartThe measures were as follows:Content Validity Index : all expCarers replied to the Greek version of eHeals-Carer, which includes 8 items, each with a 5-point response scale from 1 (strongly disagree) to 5 (strongly agree). As shown in Carers also provided the following basic sociodemographic information: gender, age, education level , employment status, carers’ relationship, living status, and being supported by a secondary carer or not), and replied to a series of questions with regard to internet use, either personal or dementia-specific online use. As part of the sociodemographic information, we have used a visual analog scale for measuring the socioeconomic position, Ladder questionnaire ,48. The In content validity, we reported the following 3 indexes: (1) Mean Item-Level Content Validity Index (Mean I-CVI), measuring the proportion of relative and very relative responses of the items; (2) Scale-Level Content Validity Index Average (S-CVI/Ave), measuring the average score of the responses of quite relevant and very relevant of every expert; and (3) the Scale Content Validity Index Universal Agreement (S-CVI/UA), measuring all items that all raters assessed as quite or highly relative. As scale CVI, we usually consider the S-CVI/Ave because the S-CVI/UA decreases as the number of raters increases .The internal consistency of the scale was assessed with a Cronbach alpha, and the dimensionality of the scale was explored with EFA. This was the first time that the scale was validated in Greek among carers, and dimensions were not hypothesized before the validation. Confirmatory factor analysis (CFA) will be calculated with the total sample of the study protocol based on the EFA findings.The Cyprus National Ethical Committee (EEBK ΕΠ 2016.01.151) and the Cyprus Commissioner for Personal Data Protection (3.28.460) approved the study. As the study was conducted in 2 countries, the study protocol also received approval by the Scientific Committee of Alzheimer Athens Association .According to the first step of the validation process, we conducted a review to identify all possible eHeals validations to decide on the methodology and avoid any replication of existing measures for this specific population.The scale has been validated and adapted in many different languages and population groups, using either convenient sample recruitment strategies or randomized recruitment techniques . In the last 3 years, the validation studies of the specific tool were increased, showing a tendency toward eHealth literacy research. Only in 1 study from Slovenia did we find the validation of an extended version of 20 items (6 factors) including the Web 2.0 parameter as discussed earlier by Norman ,50. In 2A series of studies have identified or confirmed the unidimensionality of the eHeals ,57,68-70In almost all cases, the scoring system distinguished between high and low scores without providing information for a medium level. In 12 papers, the level was calculated by summarizing all items, and in 4 validation studies, the level was calculated by summing up all items and dividing the score with the number of the scale or of the factor. The highest score of eHeals among the studies included in this review is presented in the study by Chung and Nahm  for a saIn 5 studies, the researchers used a principal component analysis (PCA), in 11 cases EFA, in 8 studies CFA, and in 3 studies either PCA or EFA and then CFA . In 4 stThis review provided the basis for our validation study. On the basis of the above results, the discussion for the use of classical test theory and item response theory in behavioral and social science , and theOur decision to adapt for a specific population was in accordance with the measurement modifications for diverse populations . The reaMean I-CVI and S-CVI/Ave was 0.93 in both cases. S-CVI/UA was 0.60.Experts made no further comment on the phrasing of the scale, apart from 3 comments on 3 different items , that did not change the final meaning of these items.As part of the reliability and construct validity, our sample comprised primary carers, mostly women , caring for their parents  living in the same household , aged younger than 60 years , having completed 12 years of education or more , mostly unemployed or pensioners , and receiving assistance from a secondary carer . Detailed demographics are presented in searching for information on different topics. Of all participants, 97.0% (98/101) visited websites; 76.2% (77/101) used social networks, such as Facebook, Twitter, and LinkedIn; 81.1% (82/101) used email to communicate; 83.1% (84/101) used interactive services ; and only 42.5% (43/101) accessed electronic learning (eLearning) courses.Of 101 participants, 92 used the internet with the more frequent reason of private internet use: In the questions regarding online search of dementia-specific information such as disease information, practical issues, legal information, and available services, almost all participants 90.0% (91/101) stated that they had accessed online dementia resources and mostly websites. Almost half of the participants  had used social networks, and 42% (42/101) had used email to communicate and searched for information with other carers, family, and health professionals. The use of interactive services and eLearning courses were the least preferred resources to communicate and receive information or training with 32.6% (33/101) and 12% (11.8/101) users equivocally.Among all participants, 51.4% (52/101) used a mobile phone to access information for dementia care or to communicate with other carers or health care professionals. Adding to the above result, of 52 participants who have used the internet on their mobile phone, 86% (45/52) have accessed websites, 54% (28/52) accessed social networks, 39% (20/52) used emails, 42% (22/52) used other interactive services, and 5% (3/52) used eLearning services through their mobile phone.ReliabilityInternal consistency of the scale was measured with Cronbach alpha of .83. All items appeared important with item-total correlations ranging between .48 and .59. In all cases, the Cronbach alpha was lower if any of the items was removed.The items with the highest frequency of replies of agreement (agree and strongly agree) were item 3 “I know how to find helpful information on the Internet concerning health and caregiving of my friend/relative (e.g. concerning the process: google search),” item 4 “I know how to use the Internet to answer my questions about the health and caregiving of my friend/relative (e.g. how to ask in order to receive a proper reply to my question),” and item 5 “I know how to use the information about the health and caregiving of my friend/relative I find on the Internet to help me .” Item 8 “I feel confident about using information from the Internet to make decisions concerning the health and caregiving of my friend/relative” had the lowest scores of agreement . This wa228=261.5 P<.001). Overall, 2 factors with eigenvalue greater than 1 were extracted, with the first factor explaining 24% of the variance and the second factor 23% (rotation sums of square loadings). After Varimax rotation, a clear structure was revealed with no cross-loadings. Items 1 to 5 loaded on the first factor and seem to tap on the information seeking aspect of eHealth literacy. Items 6 to 8 loaded on the second factor and tapped on the evaluation aspect of eHealth literacy. Reliability analysis for factor 1 provided a Cronbach alpha of .77 , and for factor 2, a Cronbach alpha of .78 .The dimensionality of the scale was explored in EFA, principal axis factoring with Varimax rotation. Kaiser-Meyer-Olkin measure sampling adequacy was 0.80, and the Bartlett test of sphericity was statistically significant  and high reliability (0.83). The data analysis supported 2 factors: information seeking and evaluation. The first factor includes the 5 items of eHeals 1 to 5, and the second factor includes 3 items 6 to 8. In the literature, we identify different categories derived from the analysis of eHeals including awareness (1 and 2), skills (3-5), information seeking (1-5 and 8 or 3-4), information appraisal (6 and 7), information engagement (5-8), and evaluation (6-8). We have also identified 2 factors related to seeking and appraisal skills as in the case of Soellner et al , but witIn eHeals, as initially developed by Norman and Skinner, more than 1 literacy is included per item of eHeals ,53. For In Greece and Cyprus, carers are the core element in the care provision of people with dementia, covering the lack of tailored services by the National Health System ,78. The We consider that this scale assists in the assessment of eHealth literacy level of carers in 2 ways. Firstly, in practice, as the health care system, not-for-profit organizations, and academic institutions could develop tailored programs for the online needs of the carers. In this way, carers may improve the way they access and evaluate dementia-specific information or information regarding their health. Secondly, in research, as we provide a validated tool for use in future studies investigating the determinants of eHealth literacy, its association with the burden and other aspects of the caregiving role, as well as a process outcome measure in intervention studies targeting eHealth literacy. In this way, eHealth inequalities may be decreased, as carers improve the management of the disease and their burden because of a better use of the available Web-based services.seeking information, and we consider important in future research on the development and validation of eHealth literacy tools that researchers include short exemplars to facilitate understanding of the how to items when related with internet users’ skills.Finally, through the validation process in this diverse population, we identified culturally specific issues related to the understanding of the items of the first-dimension Carers of people with dementia in this study are considered a convenient sample. Participation rate did not exceed 31% as revealed in the piloting phase of the study protocol. Carers in Greece and Cyprus were not easy to identify if they had not attended a dementia center. As a consequence, the final sample included in this validation was small. The study should be repeated in a larger sample, among carers of patients of other chronic diseases and could be used for cross-country comparisons between Greek and Greek-Cypriot carers.Even if the eHeals has been adapted for carers, no item about Web 2.0 has been added in the 8-item scale. We only added it in the supplementary section of the internet use characteristics . Carers The validation of eHeals-Carer provides the first questionnaire measuring perceived eHealth literacy skills adapted to carers. At the moment, there is no other scale measuring eHealth literacy levels for carers available. The development of new tools on eHealth literacy measuring functional aspects adapted to specific needs seems to be the next step in this research area. Carers of people with dementia, in the majority, are people aged older than 50 years, children, or spouses, with low use of care-specific Web-based services. The use of the online services available for carers could facilitate the carers and the long-term health care system. In Greece and Cyprus, there is a lack of services for carers, and by improving their digital skills, we could provide them with the means to support themselves and improve the care they provide. With the increased offer of Web-based services tailored for carers, the improvement of their digital skills will become more demanding in the years to come. Furthermore, public and private services in Greece and Cyprus are updating their service systems to be following technological progress. In this era, carers can be included if we provide them with adequate and appropriate eHealth literacy training programs.


This paper presents examinations of the role of the bead sequence in underwater welding. Two specimens of wet welded layers made by covered electrodes with the use of normalized S355G10+N steel were welded by a reasonable bead sequence. For each specimen, metallographic macro- and micro-scopic tests were done. Then, Vickers HV10 hardness measurements were conducted for each pad weld in the welded layer. The results show that welding in the water environment carries many problems in the stability of the welding arc, which influences the properties of the welds. The effects of refining and tempering the structure in heat-affected zones of earlier laid beads was observed, which provides a reduction of hardness. The possibility of applying two techniques while welding the layer by the wet method is described. It is stated that a reasonable bead sequence can decrease the hardness in heat-affected zones up to 40 HV10. Tempering by heat from next beads can also change the microstructure in this area by tempering martensite and can decrease susceptibility to cold cracking. The most common method of underwater welding is wet welding. The welder and the welding area are in direct contact with the surrounding environment. The process is often carried out by flux-cored arc welding (FCAW) ,2,3,4. TThe water environment can generate significant problems during welding. For welders, the biggest problems are instability of the welding arc and limited visibility ,8, whichThe high cooling rate leads to the formation of hardened structures in the heat-affected zone (HAZ) ,10. ThisExperiments in the field of welding processes in the water environment are developing annually, because underwater processes are used more in engineering .Attempts to reduce the imperfections in welded joints made in the water are made in different ways. Much attention is devoted to improving the stability of the welding arc in underwater conditions and assessing the metal transfer in the welding arc, using the following methods: visual sensing , in situFor marine and offshore constructions, high-strength, low-alloy (HSLA) steels are widely used . These cThe aim of the research was to check the influence of the role of bead sequence on the structure and properties of layers using the wet welding method for specimens welded with covered electrodes.IIW) is 0.385 according to the International Institute of Welding (IIW). As a filler material, ISO 2560-A: E 38 0 R 11 [For tests, normalized S355G10 + N steel plates with dimensions of 16 × 100 × 100 mm were chosen as the base metal (BM). This steel is often used as a material for offshore structures that may require repairs in the water environment. The carbon equivalent  wet welding process was chosen. The schema of this process is presented in For the tests, 2 specimens were made in the water (0.15 m depth) with 5 beads in each. The time between welding each bead was 120 s. Specimens were welded by different techniques. In sample S1, the beads were laid one after the other from bead 1 to bead 5. In sample S2, the beads were not laid in order. These 2 techniques were chosen because they are representative of welding techniques. In S1, a bead was tempered only by the bead welded later. In S2, beads 1 and 2 were tempered by 2 beads. The use of other techniques, such as 14253, would obtain only one bead (bead 2), which will be tempered by 2 others. That may not have allowed preparation of the planned experiments. The schemas of welding techniques for S1 and S2 specimens are presented in After welding, specimens were cut to cross-sections, and macroscopic and microscopic metallographic examinations were conducted in accordance with the EN ISO 17637:2011  standardMacroscopic tests were prepared for cross-sections of both specimens. Microscopic tests were prepared for the base material in welds and in specific areas of the samples. The first areas were located in the HAZ in the axis of each weld. The second areas were located where the HAZ from the previous weld was overlaid by the HAZ from welds deposited later. Schematic views of the areas of microscopic testing are presented in base/A, where A is the total molten area and Abase is the molten area of the BM [Macroscopic testing showed that both specimens were welded according to the assumed research plan . No impef the BM . The calf the BM . The resThe results of microscopic testing are presented in The investigated S355G10 + N steel is classified as material group 2.1 by EN ISO 9015-1:2011. In accordance with the EN-ISO 15614:1 standard, the maximum hardness of the HAZ cannot exceed 380 HV10 for material group 2.1. The hardness in welds for both specimens was lower than that in the HAZ, which is typical for welding HSLA steel in the water environment , that thThe hardness distribution in each point is presented in The results of the prepared experiments show that the technique used has a significant role in the process of repairs in underwater conditions. The technique used for preparation of specimen S1 can cause a need for further repairs, because it allows cold cracks to form.Water as a welding environment causes cold cracks to occur in the HAZ of wet welded HSLA steel. The susceptibility of steel to cold cracking can be reduced by changing the sequence of the beads during the process.The technique used for the preparation of specimen S2 allowed the structure in the HAZ of some welds to be changed. In this area, the structure indicated the presence of refined and tempered low-carbon martensite mixed with normalization structures with fine ferrite and pearlite. In each HAZ in specimen S1, brittle structures such as bainitic and martensitic were found.Welding S355G10 + N steel with the sequence used in specimen S2 (out of order) allowed a reduction of hardness in the HAZ below the critical value of 380 HV10, as stated by the EN-ISO 15614-1 standard. The lowest hardness values were measured in the HAZ in specimen S2, where the heat from beads laid later tempered this area, and in which the dilution is lower than in specimen S1.The technique used in welding specimen S2 should be used during repair procedures that have to be prepared in the water environment.The prepared experiments allow us to draw the following conclusions:


Rods of basalt plastic armature (BPA) of a periodic profile with diameters of 6, 8, 10, 16 and 20 mm on the basis of an epoxy matrix were exposed for 30 months on open stands in a moderately warm marine climate of Gelendzhik and 28 months on similar stands in an extremely cold climate of Yakutsk. For initial and exposed BPA samples, changes of mechanical parameters were determined. After the exposure in Yakutsk, an increase of ultimate compression strength by 4–12% is found, depending on the diameter of rods. After the exposure in Gelendzhik, this indicator decreases by 10–17%. Using methods of thermomechanical analysis and dynamic mechanical analysis, linear thermal expansion coefficient and glass transition temperature of epoxy matrix were measured. In an initial state, a transition from a glassy state to a highly elastic one is discovered: an  Advantages of polymeric materials reinforced with basalt fibers are discussed in a number of works , 9, 10 a“TBM” LLC (Limited Liability Company) (Yakutsk) produces basalt plastic rods of periodic screw profile, which according to mechanical strength or parameters of adhesion with concrete surpass characteristics of rods made from reinforcing steel .2SO4 and NaOH before production of composites.Basalt plastic rods are especially useful as reinforcing elements of concrete structures. In Similar mechanical properties of basalt plastics reinforced with finely chopped roving, fabrics or uniaxially oriented continuous fibers, are compared with carbon plastics and the glass-reinforced plastics based on unsaturated polyesters, epoxyphenolic and phenol-formaldehyde matrices To improve the mechanical properties and stability of BPA, heat-resistant polymer matrices , 16 withAn urgent problem of use of BPA in construction is confirmation and justification of retention of properties at a high level during long-term operation in a variety of climatic conditions. However, in all the works listed , 15, 16,In this regard, an experimental evaluation of the climate resistance of BPA was carried out after the exposure in the extremely cold (Yakutsk) climate and moderately warm marine one (Gelendzhik). The main task of the presented work is to identify the effects of climatic aging in BPA at early stages of exposure using sensitive physical methods.22.1For climate testing, BPA was prepared, being unidirectional basalt plastic rods of the periodic profile with the diameters of 6, 8, 10, 16, and 20 mm “TBM” LLC produced the armature on a technical line “Struna” in accordance with Technical Specifications 2296-001-86166796-2013 “Non-metallic composite armature made from basalt plastic”.The following components were used to produce BPA.A starting binder, which is based on epoxidation resin ED-22, cured by iso-methyltetrahydrophthalic anhydride (iso-MTHPA) in presence of an accelerator 2,4,6-tris (dimethylaminomethyl)phenol (UP-606/2) was prepared using a formulation according to RTP-SP2- 20994511-1999T .Table 1CEpoxy resins are reactive oligomers that transform into an infusible and insoluble state only under the action of hardeners.Iso-MTHPA is used as the hardener of “hot” curing of epoxy resins and compositions based on them. It ensures high physical and mechanical characteristics of cured systems, excellent waterproof properties, good electrical characteristics, and the climatic stability.The main characteristics of iso-MTHPA are shown in tris(dimethylaminomethyl)phenol (UP 606/2) as an accelerator is due to its high catalytic activity associated with presence in this compound of three tertiary amino groups and an acidic phenolic hydroxyl at the same time:Since the curing of epoxy resins by anhydrides proceeds extremely slowly, accelerators are usually introduced into these systems. A choice of 2,4,6-However, it manifests itself at rather high temperatures (above 100 °C). At processing temperatures, processability of the binder in the presence of the accelerator is maintained. Characteristics of UP-606/2 curing accelerator are presented in A fragment of chemical knots of a spatial network in the anhydride curing:An ester group formed as a result of curing is resistant to the action of organic and many inorganic acids, but is destroyed by alkalis, but thermal stability and electrical insulation properties are higher than with the use of amine hardeners.Basalt roving RBN 13-2400-4S of production by “TBM” LLC (Yakutsk). Physical and mechanical parameters of this roving RBN 13-2400-4C are shown in 2.2To assess an effect of solar radiation, temperature, humidity, precipitation and other aggressive climate factors, the rods of BPA of the periodic profile with diameters of 6, 8, 10, 16 and 20 mm were exposed during 30 months on the open stands in the moderately warm marine climate of Gelendzhik and 28 months on the similar stands in the extremely cold climate of Yakutsk Figs.  characte2, which is by 36% higher than in Yakutsk (3680 MJ/m2).The average annual relative humidity in Gelendzhik and Yakutsk differs slightly (71% and 68% respectively). During a year, precipitation in Gelendzhik is greater than in Yakutsk by a factor of 3.3 . A doze of annual total solar radiation in Gelendzhik is 5004 MJ/m2.3Z100 Zwick/Roell before the samples were destroyed in a working area. A typical example of fracture of the samples during compression tests is shown in To control the mechanical properties of BPA, compression strength 2.4DMA 242D Netzsch, a dynamic elastic modulus According to , 19, 20,2.5TMA PTLT 600 of a company Linseis. In a module of this analyzer, a measuring indenter was pressed against the sample with a constant load of 0.5 N applied to an end of the sample with the diameter from 6 mm to 20 mm and a height of 10 mm. Movement measurements of the indenter were controlled with an accuracy of 10−4 mm. The temperature in a measuring cell was automatically increased at a rate of 3 °C/min between 25 °C and 200 °C. Results were processed using Linseis Data Evaluation software for Windows, version 3.00. In the sort of measurement used, the thermomechanical analyzer operated as a highly sensitive linear dilatometer. The movement of the indenter in a direction of action of a small load over a wide range of temperatures from 200 °C to 300 °C was negligibly small, and when the temperature was increased, micromovements caused by the thermal expansion of the sample were recorded.Control of thermal expansion of the samples of BPA was carried out during heating over a wide range of temperatures using a thermomechanical analyzer 2.6It was proved in  cut out .Fig. 5Se−4 g and their geometric sizes with an accuracy of 0.001 mm. After 63 days of humidification, a process of moisture sorption was stopped and the samples were dried in the oven at the temperature of 60 °C during 35 days.The samples were previously dried in an oven at 60 °C over silica gel for 6 days, then they were held at the same temperature and relative humidity of 98 ± 2% in a desiccator above a surface of water. At the same time, measurements of masses of the samples were periodically carried out using analytical scales with an accuracy of 102.7To evaluate the effect of exposure on the structure of BPA, microsections of cross-sections of the rods with the diameters of 8, 10, 16, and 20 mm were studied. Places of saw cuts were thoroughly polished. The fractographic studies of epoxy polymers were carried out with the help of an optical stereomicroscope Olympus SZX-10 with a magnification of 20–50.33.1Compression and bending tests are the main and most common methods of control of the mechanical properties of BPA , 16, 17.Presence of periodic relief on the surface of BPA makes it difficult to determine the compression strength rameters b. When arameters  revealedAccording to the results of buckling tests, it is established that average values of A possible reason for the observed changes is the physicochemical transformations in the epoxy matrix in a surface relief layer of the rods due to the action of moisture, solar radiation and surface heating in the summer. However, the large spreads of the measured parameters 3.2The transition of the epoxy matrix from the glassy state to the highly elastic one occurs in a temperature range 90–190 °C both in the initial state and after the climatic tests in Gelendzhik and Yakutsk. During this time of action, rigidity of the armature remains high, and the polymer matrix is in the glassy state.Analysis of the dynamic mechanical characteristics of BPA reveals asymmetry of the transition of the epoxy matrix from the glassy state to the highly elastic one (the α-transition). Regularities of a change of mobility of kinetic elements under the influence of environmental factors are reproduced when the oscillation frequency changes by two orders of magnitude: from 0.5 Hz to 50 Hz Figs.  and 9.FiIn the initial state, a double minimum of t 149 °C . Such a According to data of As a result of the climatic action, the temperature of the sk Figs. , Table 7A reason for this increase of the temperature of the Distributions of the duration of sample exposure at certain temperatures have been obtained by direct measurements of the temperature in the samples obtained. The results show that in the summer months more than 120 hours of overheating of the sample temperature above 50 °C have been fixed in Yakutsk, while in Gelendzhik overheating has been fixed as about 50 hours.It can be expected that structuring of the polymer matrix is a cause of unequal changes of the strength characteristics of BPA after the exposure in two different climatic zones. The post-curing of the epoxy matrix increases adhesive strength of fiber-matrix compounds during the exposure and contributes to enhancement of the strength properties of BPA. The matrix makes the material monolithic, promotes an efficient use of the mechanical properties of fibers and a uniform distribution of forces between them. The binder protects the fibers from chemical, atmospheric and other external influences, and also takes itself part of forces developing in the material at work under the load. This is also evidenced by a kind of failures of the samples. When testing the initial BPA samples, the failure occurred according to a “panicle” type, and after the exposure according to a “cut” type, which indirectly confirms the increase of the adhesive strength of the “fiber-matrix” compound.3.3The temperature dependences of a relative thermal expansion The temperature dependences of The measurement results shown in A reason for the observed increase of 3.4D.In BPA with the diameters of 6–20 mm, a variation of the sizes of the samples from 2 to 100 mm made it possible to reveal the effects of the influence of the periodic screw profile and the damaged surface layer formed during rod cutting on the maximum moisture content w increases. This parameter increases even more noticeably after 28 months of the exposure in Yakutsk. Analysis showed that kinetic curves of a change of the mass of the samples during the sorption and desorption of moisture are satisfactorily approximated by the second Fick law in a one-dimensional approximation with constant boundary conditions similar to R is a radius of the sample, h is a sample length, λ at a moment of time t (%), λ is a characteristic length of a diffusion path, In After the exposure in the full-scale climatic conditions, the moisture transfer parameters increase. A general regularity is an increase of the values of Results presented in The parameters ectively . Thus, a3.5According to data of fractographic analysis, the structure of BPA after the exposure in the climatic conditions does not undergo significant changes. As an example, 41.After the exposure in Yakutsk, the increase of the ultimate compression strength by 4–12% was found, depending on the diameter of the rods. After the exposure in Gelendzhik this parameter decreases by 10–17%.2.The method of dynamic mechanical analysis revealed the transition from the glassy state to the highly elastic one of the epoxy matrix of BPA: the 3.A method of linear dilatometry showed the increase in the coefficient of linear thermal expansion of the rods along the reinforcement direction after the climatic action. Due to the action of cyclic temperatures, humidity, solar radiation during the climatic exposure, the effect of weakening of internal stresses of the polymer matrix at the interface with the basalt fiber predominates over the post-curing effect.4.After the exposure in the full-scale climatic conditions, the maximum moisture saturation 5.The exposure in the climatic conditions has an uneven effect on the characteristics of the moisture transfer of BPA of different cross-sections. The surface relief screw layer of BPA sorbs more moisture than the inner tightly packed  layers of the rods. With the decrease of the diameter of the rod, the part of the surface relief layer in the volume of the samples increases, which leads to the increase of 6.The fractographic studies discovered the presence of pores with the sizes up to 10–20 μm in the structure of BPA. The quantity and size of pores increase by 20–40% after the climatic exposure.7.The studied BPA has the high climatic stability and can be used for the long time under the extreme climatic conditions.In this article the experimental study of the properties of rods of BPA of periodic profile with the diameters of 6, 8, 10, 16, and 20 mm on the basis of the epoxy matrix in the initial state and after the exposure during 30 months on the open stands in the moderately warm marine climate of Gelendzhik and 28 months on similar stands in the extremely cold climate of Yakutsk. From the analysis of the results obtained, the following conclusions can be drawn:Valery Startsev: Conceived and designed the experiments; Performed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; Wrote the paper.Mikhail Lebedev: Analyzed and interpreted the data; Wrote the paper.Anatoly Kychkin: Performed the experiments; Contributed reagents, materials, analysis tools or data.Republic of Sakha (Yakutia), aimed at development of productive forces and social sphere for 2016–2020 in direction 4 «Ensuring economic development» on a theme «Complex climate tests of materials under conditions of atmosphere of Arctic climate and in marine environment».This work was supported by the framework of implementation of a project of complex scientific studies in the The authors declare no conflict of interest.No additional information is available for this paper.


The body and the prostate weights of old rats were 1.6 and 1.4 times larger than those of the young, without an increase in the prostate index (PI). The testosterone level in the blood of young rats was 1.6 times higher than that of old . In animals with BPH, the level of cfDNA in old rats (3.14 ± 0.76 ng/μl) was significantly higher than that in young rats (0.80 ± 0.14 ng/μl). The body and the prostate weights in old rats were 1.8 and 2.3 times larger, than those in young rats, with an increase in the PI. The level of testosterone in the blood of young (15.76 ± 0.51 nmol/l) and old (16.99 ± 1.1 nmol/l) rats was not significantly different. Morphological signs of BPH were observed in the prostate of both young and old rats. During the induction of BPH in the experiment, according to the level of cfDNA, cell death processes have not changed significantly in young rats but significantly increased in old rats. A similar trend was observed in the group of intact animals. The obtained data indicate that apoptosis processes are enhanced during the development of BPH despite the growth of tissues in the prostate itself.The purpose of this work was to study changes in the level of cell-free DNA (cfDNA) in the blood of young and old rats in the normal state and with induced benign prostatic hyperplasia (BPH). Male Wistar rats were divided into 4 groups—young (3 months), old (20 months), intact, or with testosterone-induced BPH. Groups with BPH were subjected to surgical castration and administration of testosterone esters at a dose of 25 mg/kg for a total of 7 injections for 20 days. In intact animals, the level of cfDNA in old rats (2.00 ± 0.14 ng/ Benign prostatic hyperplasia (BPH) is a disease with a high prevalence and continuous increase—more than half of men over 50 experience symptoms of BPH, and by the age of 80, this figure rises to 80% . The exiCfDNA is a cell death product associated with apoptosis, necrosis, and phagocytosis. Prolonged circulation of cfDNA in the blood may indicate the presence of benign or malignant pathological foci in the body; the differentiation of which is associated with the measurement of the overall level and integrity of cfDNA , 6, 7. IThe purpose of this study was to investigate the changes in the level of cfDNA in the blood of young and old rats in normal conditions and with the induction of benign prostatic hyperplasia.The study was performed on 45 male Wistar rats of two age groups: 3 and 24 months old and weighing 140-160 g and 300-350 g, respectively, purchased from the “Rappolovo” animal nursery . Animals were housed 5–7 in polypropylene cages under standard 24 h light-dark regimen (12L : 12D) at 22 ± 2°C with relative humidity at 50 ± 10%. Rats received standard laboratory crop from Laboratorkorm Ltd.  and tap water ad libitum. All animal experiments were performed following the approval of the N.N. Petrov Research Institute of Oncology Ethic Committee within the frame of rules declared by the European Treaty ETS No. 123 and in accordance with the requirements of Directive 2010/63/EU.7 days after placement, animals in both age groups were randomized to the intact control group and the BPH induction group . On the first day of the experiment, surgical castration was performed: orchidectomy was performed in sterile conditions under ether anesthesia, by an incision in the midline of the scrotum. After ligation of the spermatic cord and blood vessels, the testicles with appendages were removed. The stump of the spermatic cord was refueled through the inguinal canal into the abdominal cavity, after which the scrotum was sutured. Starting from the 7th day after orchidectomy and then every other day, animals received subcutaneous injections of testosterone  in a dose of 25 mg/kg body weight, a total of 7 injections for 20 days. Rats were sacrificed on the 7th day after the last injection (the 36th day after castration), the blood was taken to determine cfDNA and serum testosterone, and the prostate was extracted.A full autopsy was performed on all animals. The prostate was isolated as a complex of the dorsolateral prostate, ventral lobes, and seminal vesicles with anterior prostate lobes (coagulating glands). The prostates were cleared of other tissues, the lobes were divided and weighed, the dorsolateral section was weighed separately, ventral and anterior lobes pairwise, and then fixed in 10% buffered neutral formalin, and then standard histological processing was carried out. To evaluate the prostate enlargement, the prostatic index (PI) was calculated as the ratio of the dorsolateral and ventral prostate fraction weights in mg/100 g of body weight.μm and then stained with hematoxylin-eosin.Prostate tissue blocks were embedded in paraffin and cut at 5 https://sigma-aldrich.com). Absorption with a wavelength of 450 ± 10 nm was measured on a Microplate ChroMate Reader tablet . We measured the concentration of the DNA of the ELISA kit-positive control by spectrophotometer . By diluting this positive control, calibration curves were constructed to quantify the DNA in our samples.The content of cell-free DNA (cfDNA) in the blood plasma was determined by ELISA using the Cell Death Detection ELISA kit . The definition is based on quantitative sandwich ELISA. Two mouse antibodies produced against DNA (single and double stranded) and histones , specifically binding mono- and oligonucleosomes derived from the nuclei of eukaryotic cells . Absorption with a wavelength of 450 ± 10 nm was measured on a Microplate Reader ChroMate tablet .t-criterion. Values of p < 0.05 were considered statistically significant.Data are presented as mean ± SEM (standard error of the mean). The analysis was performed using the GraphPad Prism 7 software; the significance of the differences was estimated by Student's p < 0.05). The body weight of old rats was 1.6 times larger than that of the young (p < 0.001), and the prostate weight was 1.4 times larger. Differences in PI values in young and old rats were not statistically significant. The testosterone level in the blood of young rats was 1.6 times higher than that of the old (p < 0.05) (The results of the study are shown in  < 0.05) . A morph < 0.05) .p < 0.001). The body weight of old rats was 1.8 times larger than that of the young (p < 0.001) and the prostate weight was 2.3 times larger (p < 0.001). The PI value of old BPH rats was statistically significantly higher than that of old intact rats (p < 0.05). The level of testosterone in the blood of young and old rats was not significantly different (In the group of animals with benign prostatic hyperplasia, the level of cfDNA in old rats was similarly significantly higher than that in young rats (ifferent . MorpholWe have found a significant increase in the level of cfDNA in old rats compared to young ones, which correlates with the literature data on age-related increases in the level of cfDNA in humans , 9. It sToday, it is known that the presence of chronic inflammation, both in humans and in animals, is a risk factor for precancerous and cancerous conditions in various organs, including the prostate. At the same time, the development of BPH is associated with an imbalance of cell proliferation and apoptosis . It is bAnother explanation for an increase in cell death and in the overall level of cfDNA is age-related circulatory disorders and local hypoxia, which lead to the formation of ischemic foci in the pelvic organs . As a reIn our experiment, among old rats with the development of BPH, an increase in cfDNA level correlated with the largest increase in THE prostate weight  and prosOn the other side, it is possible to speak about the hormonal nature of the development of BPH and its connection with THE natural aging processes. In our study, testosterone levels in old intact rats were statistically significantly lower than those in young intact animals; however, the level of cfDNA in young intact rats was significantly lower. Testosterone has been shown to protect cells from damage caused by oxidative stress . At the Another important thing is that in young rats with BPH, the level of cfDNA was significantly lower than that in old rats, with a relatively equal level of testosterone. At the same time, the body weight and prostate weight in young rats were almost two times less than those in old rats. Thus, the effects of testosterone on old and young rats with the development of BPH differed significantly. Judging by the level of cfDNA, the processes of cell death did not change significantly after the action of testosterone in young animals and increased in old ones. Probably, in young rats, testosterone stimulates proliferative processes , therebyWe assume that an increase in the level of cfDNA in old rats is associated with activation of apoptosis accompanying the growth of prostate tissue, compared with young animals. On the one hand, the growth of prostate tissue during the development of BPH in old rats is possibly accompanied by the active secretion of small amounts of DNA , which tBPH and prostate cancer are a significant problem for an aging male population all over the world, and it is expected that the urgency of this problem will only increase due to the increase in life expectancy. However, the diagnosis of both benign and malignant prostate pathologies remains nonspecific and subjective, which requires additional instrumental studies to confirm the diagnosis. This not only affects the patient's quality of life and mortality but also carries an economic burden for the whole health care system. In particular, the specificity of the traditional PSA test can vary from 30% to 70%, in most cases, requires a biopsy, and is not able to differentiate between BPH and prostate cancer . In addiThe level of cfDNA in old and young rats differed significantly. Upon induction of BPH in the experiment, judging by the level of cfDNA, cell death processes did not change significantly in young animals but significantly increased in old animals. A similar trend was observed in the group of intact animals; however, it was significantly lower than that in BPH. Thus, in aging animals, cfDNA reflected the progression of BPH from partial atrophy of prostate tissues to progressive hyperplasia, which was accompanied by apoptosis and increased levels of cfDNA in the blood. Our data suggest that apoptosis is enhanced during the development of BPH despite the growth of tissues in the prostate itself. Considering that BPH is attributed to the diseases of aging men, the results confirm the need for further research of the diagnostic value of cfDNA as a noninvasive biomarker, which will provide patients with personalized diagnostics and more accurate treatment.