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The properties of coal fly ash vary significantly depending on factors such as coal type, combustion conditions, and flue gas emission reduction methods. This study investigates the influence of particle size fractionation on the chemical composition, mineralogical structure, and thermal behaviour of two types of fly ash: high calcium ash derived from lignite (S1) and silica-rich ash from bituminous coal (S2). Dry aerodynamic separation was used to obtain distinct size fractions, which were then subjected to a comprehensive characterisation including X-ray fluorescence, X-ray diffraction, scanning electron microscopy, and thermal analysis. The results reveal notable differences between the S1 and S2 ashes and between their size fractions. The finer fractions (< 20 μm) of S1 showed an increased calcium and sulphur content, while the coarser fractions (> 100 μm) contained more silica and alumina. The S2 ash exhibited a higher overall silica content, with alkali metals concentrated in finer fractions. Thermal analysis demonstrated distinct behaviours for each type and fraction of ash. Fine fractions of S1 ash showed SO2 emission at elevated temperatures, while S2 ash exhibited greater CO2 gas emission. After thermal treatment, the recrystallisation of the glassy phase was observed for S1, while the S2 ashes were more prone to melting and agglomeration. The study highlights the potential for the customised utilisation of specific ash fractions in various applications, such as geopolymer synthesis, adsorbent materials, and refractory products. This comprehensive characterisation contributes to a better understanding of fly ash properties and their dependence on particle size, providing valuable insights to optimise fly ash utilisation in various industries. The findings suggest strategies for a more efficient use of fly ash resources, particularly relevant in the context of decreasing fly ash availability due to the phase-out of coal power plants. [ABSTRACT FROM AUTHOR]

Purpose: People living with HIV are twice as likely to develop cardiovascular diseases (CVDs) and myocardial infarction related to atherosclerosis than the uninfected population. This study aimed to evaluate the prevalence of subclinical atherosclerosis in a young, mid-eastern European population of PLWH receiving ART for undetectable viremia. Patients and Methods: This was a single-centre study. We included 34 patients below 50 years old, treated in Szczecin, Poland, with confirmed HIV-1 infection, treated with antiretroviral therapy (ART), and undetectable viremia. All patients underwent coronary artery computed tomography (CACT), carotid artery intima-media thickness (IMT) evaluation, and echocardiography. Results: In the primary assessment, only two (5.8%) patients had an increased CVD risk calculated using the Framingham Risk Score (FRS), but we identified coronary or carotid plaques in 26.5% of the patients. Neither traditional risk factors nor those associated with HIV significantly influenced the presence of the plaque. IMT was significantly positively correlated with age and the FRS (R=0.38, p=0.04). Relative wall thickness assessed in echocardiography was higher in those with plaque (0.49 vs 0.44, p=0.04) and significantly correlated with IMT (R=0.38, p=0.04). Conclusion: In our population, more than a quarter of PLWH with undetectable viremia had subclinical atherosclerosis in either the coronary or carotid arteries. The FRS underpredicted atherosclerosis in this population. The role of RWT as a possible early marker of atherosclerosis needs further studies. [ABSTRACT FROM AUTHOR]

The manuscript presents a new manufacturing technology for the production of hollow railway axle forgings. The manufacturing technology analyzed is based on three-roll skew rolling (TRSR) using a computer numerically controlled (CNC) rolling mill. The study focused on comparing the rolling capability of hollow products without and with a mandrel calibrating the hole of the forging. The influence of tube billet size on the rolling process was also analyzed. FE analysis and experimental studies were carried out. An analysis of the accuracy of the internal hole of the forging depending on the adopted parameters of the rolling process was carried out. Based on numerical simulations, the state of strain and the flow pattern of the material and temperature distribution during rolling were determined. The force parameters of the rolling process of hollow forgings were also analyzed. Based on the research, a two-stage rolling technology for rolling hollow railway axle forgings was proposed. The results obtained indicate the suitability of using a calibrating mandrel to improve hole accuracy in hollow forgings rolled from a tubular billet. The gap c between the bore diameter of the forging and the diameter of the mandrel was measured. Increasing the tubular billet dimensions from Ø42.4 × 10 mm to Ø48.3 × 12.5 mm reduced the gap c by 49.8%. Rolling the billet Ø51 × 14.2 mm in two passes compared to rolling in one pass reduced the gap c by 45.5%. [ABSTRACT FROM AUTHOR]

The article presents and discusses the problem of determining and characterizing the cracking limits of cross-rolled specimens. The limit values were determined in accordance with the hybrid Pater criterion. For the study, the author’s test method was used, which allows the determination of the cracking moment, formed as a result of the Mannesmann effect during the compression of specimens in the channel. In order to determine the values needed to describe the cracking criterion, it was necessary to perform laboratory tests and numerical simulations of the process of compression in the channel of discs made of EA1T steel under hot forming conditions. Experimental tests were carried out for forming processes at 950 °C, 1050 °C and 1150 °C. The tested material had a disc shape with a diameter of 40 mm and a length of 20 mm, during the pressing process the diameter of the disc was reduced to a diameter of 38 mm. The increase in forming temperature caused a significant increase in the forming path until cracking occurred. Numerical tests were carried out in the finite element calculation environment Simufact.Forming 2021. The stress and strain distributions in the specimen axis were analysed during the tests, which were then used to calculate the hybrid cracking criterion limit according to Pater. After calculations according to the Pater criterion and after statistical analysis, the cracking criterion limits were obtained. [ABSTRACT FROM AUTHOR]

This article presents a study to estimate the possibility of determining the shape and size of a Mannesmann effect crack using the finite element method. Experimental tests were carried out to obtain reference specimens with a crack. A rotational compression test of cylindrical specimens in a channel was used for the experimental studies. Finite element tests were carried out using nine ductile fracture criteria. In the first stage of the study, using the rotational compression test and the finite element method, the limit values of the fracture criteria were determined. In the second stage, the development of a Mannesmann effect crack was simulated using the limit values of the fracture criteria using the finite element method. Based on the analysis, it was found that the greatest agreement in terms of void shape and size obtained in finite element method and experiment was obtained for the Ayada criterion. Analysis of the progression of the shape of the void formed using the Ayada criterion showed that crack initiation occurs as a result of maximum principal stress. The development of the resulting void is the result of the action of the maximum shear stress as well as the maximum principal stress. [ABSTRACT FROM AUTHOR]

Background: People living with human immunodeficiency virus (HIV) (PLWH) have increased risk of developing diastolic dysfunction (DD) and heart failure with preserved ejection fraction (EF). In this observational study, we evaluated DD and left ventricular hypertrophy (LVH) in PLWH receiving antiretroviral therapy (ART) with undetectable viremia. Methods: We conducted an observational study. All participants underwent transthoracic echocardiography to assess chamber size and systolic and diastolic function. Results: Most patients showed concentric remodeling without LVH. All patients had normal left ventricle systolic function (EF median 61.3%, interquartile range: 57.8–66.2). None fulfilled the DD criteria, while two patients (6%) had undetermined diastolic function. Twenty percent (n = 7) of patients had an enlarged left atrium (left atrium volume index [LAVI] > 34 cm3/m2). These patients had a significantly lower CD4+ count (771.53 ± 252.81 vs. 446.00 ± 219.02, p = 0.01) and higher relative wall thickness (0.50 ± 0.05 vs. 0.44 ± 0.06, p = 0.03). Patients without immune restoration above 500 cells/μL had significantly higher LAVI (33.92 ± 6.63 vs. 24.91 ± 7.03, p = 0.01). Conclusions: One-fifth of patients had left atrial enlargement associated with worse immune restoration during ART treatment. The mechanism of left atrial enlargement and its association with cardiovascular risk require further investigations. [ABSTRACT FROM AUTHOR]

The article focuses on the role of modern logistics 4.0 technologies and lean management in optimizing ancillary processes in intralogistics. The literature review presents critical aspects of intralogistics, including using autonomous mobile robots (AMR) and the challenges associated with their successful implementation. The article also discusses the concepts of Industry 4.0 and Industry 5.0. highlighting the importance of synergies between workers and advanced technologies. In optimizing logistics processes, the authors emphasize the importance of lean management and tools such as 5S and Kaizen. The authors analyze the research gap related to the organization of auxiliary processes, intralogistics, and the introduction of modern technologies. The lack of good practices and strategies for implementing new technologies for ancillary processes makes this a critical issue for managers and production engineers. The article provides practical strategies that can be implemented in companies. It is a valuable resource for managers seeking to manage intralogistics and effectively improve support processes in manufacturing plants. In summary, the article provides a comprehensive look at modern approaches to optimizing support processes in internal logistics. It highlights the importance of integrating modern logistics technologies with lean management principles, which can increase companies' efficiency and competitiveness. [ABSTRACT FROM AUTHOR]

Remanufacturing processes are one of the key pillars of the so-called closed-cycle economy. Unfortunately, the design and organization of such processes pose a significant problem, due to, among other things, the high variability of the process as a consequence of both the degree of wear and tear and the quality of the remanufactured components. This article presents a method for optimizing the flow of the brake caliper remanufacturing process in the MTO (make-to-order) model. For the optimization process, the system dynamics (SD) method, which belongs to a group of simulation methods, was used. The developed model allows, in particular, the prediction of the number of components at the input to the regeneration process and the method of defining the size of the transport batch and evaluating its impact on the length of the production cycle of the batch of regenerated products. The issues of staffing management at individual positions and the organization of transport operations with variable production batch sizes were also discussed. The provided experiments have shown that reducing the size of the transport batch contributes to shortening the production order execution time, both with standard and increased staffing. [ABSTRACT FROM AUTHOR]

The paper presents the results of research on the influence of the components of composition on the physicochemical properties of cross-linked poly(sodium acrylate)/sodium silicate hydrogels. The results of the rheological measurements showed that an increasing share of polyacrylate in the sample causes a shift of the cross-over point towards longer times and improves mechanical properties. In turn, increasing the share of sodium silicate has a positive effect on extending the fire insulation time (I). TG/DSC analysis indicated that if the sample contained more than 50 wt.% of polymer, the thermal decomposition was a three-stage process, while if the sample contained more water glass, the decomposition was two stage. UV-Vis measurements and SEM analysis confirmed, inter alia, that increasing the share of polyacrylate causes improvement of the optical parameters and homogeneity of the tested hydrogels. The presented results suggest that by controlling the share of the main components of the silicate–polymer hydrogels, it is possible to control their mechanical, optical and thermal properties. Multiplication of the layers or increasing their thickness improves their fire-retardant properties. [ABSTRACT FROM AUTHOR]

The aim of the paper is to assess the impact of the effectiveness of bonding steel elements with paint coating. The adhesive joints were made using two types of the adhesives: two-component epoxy resin adhesive based on Bisphenol A and polyurethane. Three types of adhesive joints were made: (i) reference samples, (ii) samples with a paint polyester coating, and (iii) samples with a zinc primer and paint polyester coating. These coatings were applied using the electrokinetic method. A shear strength test of the adhesive joints (EN DIN 1465 standard), a coating adhesion test (ASTM D3359-B standard), and surface wettability tests (based on contact angle) were used. Through analyzing the test results, it can be seen that the strength of the adhesive joints of the reference samples made with epoxy adhesive is 46% lower than that of the specimens with primer and paint coating applied. However, in the case of the adhesive joints made with the polyurethane adhesive, the aforementioned difference in the strength value of the adhesive joints of the reference samples and paint-coated samples with an applied primer is 76%. Adherends with a paint coating and a previously applied primer obtained the lowest value of the contact angle (38.72°) and are characterized by good wettability. [ABSTRACT FROM AUTHOR]

The article addresses the problem of material fracture in metal forming processes. In the specialized literature as well as in the available technical catalogues, it is difficult to find the values of the damage functions according to the many available ductile fracture criteria for specific materials and specific shaping cases. Hence, experimental studies and numerical analyses were undertaken to determine the critical values of the damage function according to 9 ductile fracture criteria. The article undertakes to compare the values of damage functions obtained in classical calibration tests - tensile and torsion tests, under cold forming conditions. Two materials were selected for the study, i.e. CW008A copper and S355 steel. The presented research methodology includes experimental tests and numerical simulation carried out using Simufact. Forming v.15 software. The analysis of the obtained data made it possible to determine the value of damage using to various criteria, including the growth and coalescence of micro cracks (Rice&Tracey, Oyane, Argon), the initiation and development of ductile cracking in forming processes (Freudenthal, Cockroft-Latham, Brozzo, Oh) and using extended phenomenological models based on the history of stress triaxiality (Ayada) or the mean and equivalent stress (Zhan). The study showed that the value of the damage function is affected by the type of calibration test, the material grade and the geometry of the samples. [ABSTRACT FROM AUTHOR]

Due to their unique properties, hydrogels can be used in many areas of life and science. The main purpose of this work was to present the possibility of using hydrogels as a kind of fire retardant material itself and as a medium in fire retardant materials used, among others, as the extinguishing agents for fires and the suppression agents for the self-ignition of coal in mines (where their low viscosity and high ability to penetration of the protected material is used), protective layers in fabrics and the so-called robot skin (most often applied in the layer-by-layer system), filling in the fire retardant window panels (mostly hybrid hydrogels or hydrogel copolymers are used) and protective emulsions of the wooden elements used in construction and furniture joinery (mainly in combination with silicate and phosphate derivatives). In the presented applications, hydrogels can be used alone, e.g. due to the large water capacity and at the same time the possibility of dilution, or in combination with fire retardants, what very often allows for the multiplication of the extinguishing or fire retardant effect. Due to the multitude of available studies and the speed of scientific development, this review is focused mainly on publications written after 2015. [ABSTRACT FROM AUTHOR]

The purpose of this review was to present clay–cement suspensions that are mainly used in the construction and renovation of hydrotechnical facilities and flood protection. We present the characteristics of clay–cement slurries that are used in waterproofing barriers. One of their significant components are clays of different types and origins. Examples of kaolin-type and smectite-type clays, which are associated minerals, as balanced components of suspensions are presented. As mentioned, before the hydration process, barriers are suspended, and the main test methods are rheometric measurements. Their rheological parameters, extremely important from the point of view of injection mechanics, are shown. The higher the flow limit and faster the reconstruction of thixotropic structures, the higher the energy input of the injection processes. After the hydration process, it is important to form agglomerates and seal the barrier; therefore, we present a summary of the strength results, filtration coefficients and microscopic images of the resulting structures. Additional properties of such barriers in terms of limiting contaminant migration are indicated. One of the aspects affecting the use of liquid slurries is their application methods; thus, a summary of low-energy slurry injection methods is also presented. [ABSTRACT FROM AUTHOR]

Hot ring rolling is a method of forming ring products with large diameters in relation to the cross-sectional dimensions. This process is a complex incremental metal forming process. It is characterized by high dynamics and continuous change of shape of the rolled ring. Important process parameters are the rotational speed (and the peripheral speed dependent thereon) and the infeed speed of the main roll. In industry, the goal is to be as effi cient as possible, so it makes sense to use the highest possible speeds in the process. An important issue is to determine the ratio of the peripheral speed of the main roll to the infeed of that roll. If the ratio of these speeds is too low, the ring is distorted due to the occurrence of slippage between the tools and the ring being shaped. The objective of the research presented in this study was to determine the limiting ratio of infeed speed to peripheral speed of the main roll. Based on the tests conducted, a range of values for the ratio of the two speeds of the main roll at which the process can be performed properly was determined. [ABSTRACT FROM AUTHOR]

For decades, steel has been a crucial structural material. Mainly low-alloy steel grade 42CrMo4 is utilized for manufacturing forgings. This paper investigates the microstructure and hardness development of the 42CrMo4 steel hollow component with an outer flange. The component has been formed via cold forging in combination with extrusion and upsetting technologies. Prior to forming, the workpiece was annealed to obtain hardness at the level of 181±9 HV0.3. The FEM analysis reveals the areas that undergo higher stress and strain. The flow lines macrostructure and microstructure of hollow parts were investigated using light optical microscopy (LOM) and scanning electron microscopy (SEM) equipped with EDS. Vickers hardness allows identifying the work hardening of the crucial element areas. The microstructure consists of ferrite matrix and semispherical carbides. Laboratory studies confirm appropriate flow lines arrangement, which corresponds well to those shown by FEM computer simulations. The highest hardness at the level of 293±7 HV0.3 was identified in the flange area, where the material shows a higher distribution of effective strain revealed by FEM. Cold metal forming results in work-hardening of the steel. The work hardening ranges up to 1.62 of the initial 42CrMo4 steel hardness. The metal forming process did not affect the microstructural uniformity of the flanged hollow part. The final outer flange component presents high quality and is free from plastic deformation nonuniformities. [ABSTRACT FROM AUTHOR]

Simple Summary: The purpose of our study was to determine how CBD extract influences resistance in the hemolymph (insect blood) of honey bees in the hive test. The bees were divided into 3 groups: (CSy) bees fed with CBD in sugar syrup; (CSt) cotton strip with CBD placed in hive, (C) control bees fed sugar syrup. To determine the state of immunity, we used the analysis of the activity of the proteolytic system and biochemical markers, such as "liver tests", and the concentration of selected ions and key compounds for the functioning of the organism. CBD extract increased the total protein concentration, proteases and their inhibitor activities in each age (except for acidic protease activities in the 21st and 28th day and alkaline protease inhibitor activities in the 28th day in the CSt group), increased concentrations of markers: ALP, AST, ALT; and glucose; triglycerides; cholesterol and creatinine. A decrease in concentration in experimental groups was noticed for urea acid and albumin compared to group C. Higher activities/concentrations of most of parameters were obtained in the CSy compared to the CSt and C. The CBD supplementation can positively influence bees' resistance. We examined how CBD extract influences the activity of the immune system in the hemolymph of honey bees in the hive test. The bees were divided into 3 groups: (CSy) bees fed with CBD in sugar syrup with glycerin; (CSt) cotton strip with CBD placed in hive bees fed pure sugar syrup, (C) control bees fed sugar syrup with glycerin. CBD extract increased the total protein concentrations, proteases and their inhibitor activities in each age (the except for acidic protease activities in the 21st and 28th day and alkaline protease inhibitor activities in the 28th day in CSt group) in comparison with group C. In the groups with the extract there was also an increase in the enzymatic marker activities: ALP, AST (decrease on day 28 for CSt), ALT; and non-enzymatic marker concentrations: glucose; triglycerides; cholesterol and creatinine. The urea acid and albumin concentrations were lower in CSy and CSt groups compared to the C group (higher concentration of albumin was displayed by control bees). Higher activities/concentrations of most of biochemical parameters were obtained in the CSy compared to the CSt and C. CBD supplementation can positively influence workers' immune system. [ABSTRACT FROM AUTHOR]

We examined the effect of hemp extract on the activity of the antioxidant system (catalase, peroxidase, glutathione, superoxide dismutase, and total antioxidant capacity) in the hemolymph of adult honey bees (Apis mellifera). The bees were divided into three groups: (1) an experimental group fed with pure sugar syrup with cotton strips soaked with hemp extract put inside the cage; (2) an experimental group fed with a mixture of sugar syrup with hemp extract; and (3) a control group fed with a mixture of sugar and a water–glycerine solution. Hemolymph samples were collected on the 1st day of this study and then every week, until all bees in the group died. The activities of all antioxidant enzymes were higher for the experimental groups, compared to those for the control group. The highest antioxidant activities were noted in the group supplemented with cannabis with the use of syringes. Supplementation with hemp also increased the lifespan of bees in this group compared to that of the bees consuming only sugar syrup (control: 35 days), with 49 and 52 days for groups of cannabis on strips and in syrup, respectively. Hemp extract, thanks to its antioxidant properties, increased the activities of key antioxidant enzymes that protect the bee's organisms against free radicals and thus delay the aging processes. [ABSTRACT FROM AUTHOR]

Three-dimensionally-printed aortic templates are increasingly being used to aid in the modification of stent grafts in the treatment of urgent, complex aortic disorders, often of an emergency nature. The direct contact between the aortic template and the stent graft implies the necessity of complete sterility. Currently, the efficacy of sterilizing aortic templates and the effect of sterilization on the geometry of tubular aortic models are unknown. A complex case of aortic arch dissection was selected to prepare a 3D-printed aortic arch template, which was then manufactured in six popular printing materials: polylactic acid (PLA), nylon, polypropylene (PP), polyethylene terephthalate glycol (PETG), and a rigid and flexible photopolymer resin using fused deposition modeling (FDM) and stereolithography (SLA). The 3D models were contaminated with Geobacillus stearothermophilus broth and Bacillus atrophaeus. The sterilization was performed using three different methods: heat (105 °C and 121 °C), hydrogen peroxide plasma, and ethylene oxide gas. Before and after sterilization, the aortic templates were scanned using computed tomography to detect any changes in their morphology by comparing the dimensions. All sterilization methods were effective in the elimination of microorganisms. Steam sterilization in an autoclave at 121 °C caused significant deformation of the aortic templates made of PLA, PETG, and PP. The other materials had stable geometries, and changes during mesh comparisons were found to be submillimeter. Similarly, plasma, gas, and heat at 105 °C did not change the shapes of aortic templates observed macroscopically and using mesh analysis. All mean geometry differences were smaller than 0.5 mm. All sterilization protocols tested in our study were equally effective in destroying microorganisms; however, differences occurred in the ability to induce 3D object deformation. Sterilization at high temperatures deformed aortic templates composed of PLA, PETG, and PP. This method was suitable for nylon, flexible, and rigid resin-based models. Importantly, plasma and gas sterilization were appropriate for all tested printing materials, including PLA, PETG, PP, nylon, flexible and rigid resins. Moreover, sterilization of all the printed models using our novel protocol for steam autoclaving at 105 °C was also 100% effective, which could represent a significant advantage for health centers, which can therefore use one of the most popular and cheap methods of medical equipment disinfection for the sterilization of 3D models as well. [ABSTRACT FROM AUTHOR]

This paper presents the modeling of a cold forging process for a rotary sleeve. The process of forging a EN 42CrMo4 steel part was first modeled numerically by the finite element method using simulation software DEFORM 3D ver. 11.0. After that, the developed forging process was verified by experimental tests carried out in laboratory conditions with the use of 1:2 scale tools and a material model of aluminum alloy EN AW-6060. Finite element method (FEM) results demonstrated that rotary sleeves could be formed from tubes by cold forging. Results of the experimental tests showed, however, that the material inside the hole of the work piece might not adhere to the surface of the sizing pin. Distributions of strain and stress during the forging process are determined. Geometrical parameters of forged parts obtained in experimental tests are compliant with the dimensions of forged parts simulated by FEM. In addition, experimental forces of the forging process show a high agreement with the forces obtained in FEM simulations. [ABSTRACT FROM AUTHOR]

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Evolution has created different castes of females in eusocial haplodiploids. The difference between them lies in their functions and vulnerability but above all in their reproductive potentials. Honeybee queens are highly fertile. On the other hand, the workers are facultatively sterile. However, rebel workers, i.e. workers that develop in a queenless colony, reproduce more often than normal workers. As a result, the fat body of these bees, which apart from acting as the energy reserve, is also the site of numerous metabolic processes, had to specialize in different functions perfected over millions of years of eusocial evolution. Assuming that the variety of functions manifests itself in the pleomorphic structure of the fat body cells, we predicted that also different parts of the fat body, e.g. from different segments of the abdomen, contain different sets of cells. Such differences could be expected between queens, rebels and normal workers, i.e. females with dramatically different reproductive potentials. We confirmed all these expectations. Although all bees had the same types of cells, their proportion and segmental character corresponded with the caste reproductive potential and physiological characteristics shaped in the evolutionary process. The females with an increased reproductive potential were characterized by the presence of oenocytes in the third tergite and high concentrations of compounds responsible for energy reserves, like glucose, glycogen and triglycerides. Queens had very large trophocytes, especially in the third tergite. Only in workers did we observe intercellular spaces in all the segments of the fat body, as well as high protein concentrations—especially in the sternite. As expected, the rebels combined many features of the queens and normal workers, what with other findings can help understand the ways that led to the origin of different castes in females of eusocial Hymenoptera. [ABSTRACT FROM AUTHOR]

The purpose of this study was to report sex- and age-specific physical fitness level in Polish children aged 4 to 7. 11.709 children participated in the study, including 5.684 girls and 6.025 boys aged 4 to 7 who attended kindergarten institutions throughout Poland. Physical fitness was assessed using four tests developed by Sekita including shuttle run 4 × 5 m with moving the block, standing long jump, throwing 1 kg medicine ball with two hands above the head and 20 m run. Percentile charts were developed separately for males and females using the LMS method. Boys showed higher physical fitness values than girls. In addition, an increase in the level of physical fitness was observed along with the age of the subjects. The developed reference values by age and sex in the field of physical fitness can be used for diagnostic purposes and assessing the level of physical fitness of preschool children. In addition, they can be helpful for healthcare professionals, parents and teachers to develop children's motor activation programs and monitor their physical fitness. [ABSTRACT FROM AUTHOR]

The paper presents an innovative method of metal forming of hollow flanged elements. In this process, flanges are formed using a movable sleeve, which moves in the opposite direction to the punch. The movement of the sleeve causes a closed impression to open, due to which the flange is also formed in a semi-free impression. The tube billets were made of the 42CrMo4 grade steel deformed under the cold metal forming conditions. The calculations were conducted using the finite elements method in Deform-2D/3D. Various technological parameters of the process were analysed, among others the diameter of the flange and the initial height of the impression of the movable sleeve. On the basis of the obtained results, the limiting phenomena of the process were determined and the influence of the analysed technological parameters on these phenomena were presented. [ABSTRACT FROM AUTHOR]

Imidacloprid (IMD) may affect proteolysis, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and global DNA methylation in honeybees. Queens, drones, and workers aged 1 or 20 days were exposed (free-flying colonies) to IMD (5 ppb and 200 ppb) in their diet. As a result, the colony depopulation did not occurred. IMD disturbed hemolymph/cuticle proteolysis; deactivated most of the cuticle protease inhibitors, activated hemolymph thiol and metal proteases and cuticle thiol proteases; downregulated ALP, ALT, AST; and increased DNA methylation in a caste- and age-dependent manner. The response in queens and workers differed, possibly due to eusocial evolution. Higher IMD dose had greater effects. The responses of ALP, ALT, AST, and DNA may reflect acceleration of biochemical senescence and epigenetic adaptation to IMD. All these biochemical side effects may lead to colony depopulation during future biotic/abiotic stress. [ABSTRACT FROM AUTHOR]

The article presents the problem of material cracking in metal forming processes. The authors describe and compare the values of damage obtained in classic tensile and compression tests as well as rotational compression of 1050A aluminium alloy in cold working conditions. The presented research methodology contains experimental tests as well as a numerical simulation conducted in Simufact.Forming v.15. An analysis of the damage values was calculated according to the normalised Cockcroft-Latham criterion. The research conducted showed that the damage value in the rotational compression test is greater than the values obtained by the means of other tests. [ABSTRACT FROM AUTHOR]

A method for determining the critical value of the Cockcroft–Latham damage criterion is presented using the example of R260 railway steel. The determinations were performed using a rotary compression test specially developed for that purpose. The main object of the proposed test was to provide the best possible representation of the state of stress generated by cross-wedge rolling. The rotary compression test was performed in two stages: in the first stage, experimental tests were conducted to establish the moment of cracking of the specimen, and in the second stage, numerical modeling was used to determine the critical value of the Cockcroft–Latham criterion for the experimentally established cracking moment. The critical value of the Cockcroft–Latham criterion was determined under hot forming conditions. [ABSTRACT FROM AUTHOR]

This article presents the results of computer simulations used to investigate the forming of a hollow coldworked forging with an outer flange. Numerical simulations were performed in Deform 2D/3D using a calculation module for axial-symmetric cases. A ϕ57×12.5 mm tube-shaped billet from 42CrMo4 grade steel was used. The forming process involved two and three stages, consisting of extrusion the shaft portion and forging the flange. The objective of this research was to determine the accuracy of the forming process used to produce the hollow part. This technology was analyzed using the effective strain distributions, the Cockcroft-Latham fracture criterion values, and the forming force progression. The results showed that it was possible to use this three-stage process to forge elements from a tube-shaped billet. [ABSTRACT FROM AUTHOR]

This paper presents the results of a numerical analysis of a cold forging process for a hollow flanged part. The analysis was performed using Deform 2D/3D. 42CrMo4 steel tubes were used as the billet material, and their material model in the annealed state was described by a constitutive equation. The forming process was performed in six stages with the use of methods such as extrusion with a movable sleeve, open-die extrusion, and upsetting. The objective of the study was to determine whether the proposed forging technique could be used to produce hollow parts with flanges. The determination was made based on the analysis of product geometry quality and process parameters, including the Cockcroft-Latham ductile fracture criterion and forming forces. [ABSTRACT FROM AUTHOR]

Low-melting frits are most often applied in the form of coatings for ceramic building materials, i.e., roof tiles and brick façade. A thin layer of glaze or sintered engobe improves decorative and functional properties of the final product. The roof tiles are fired in the low temperature range (1000–1200 °C). There are expected solutions which will allow obtaining a smooth layer of glaze without deteriorating mechanical and chemical properties. Thus, it is important to find a solution that meets the above requirements. The aim of this study was to analyze the effect of bismuth (III) oxide on the properties of low-melting different commercial frits used as a main component of glaze for ceramic roof tiles. Three commercial frits were modified with the addition of bismuth (III) oxide in the amount of 5 and 10 wt%. In the first stage, the results of the dilatometric and high-temperature microscopy analysis are shown. [ABSTRACT FROM AUTHOR]

Ductile fracture is one of the most common failure modes in hot metal forming. It can be predicted by means of so-called damage functions that describe the relation between stress, deformation and fracture initiation. A practical use of these functions requires the knowledge of the critical damage value of the material that is determined by calibration tests based on compression, tension and torsion. For the prediction to be correct, one must ensure that the modelled and real stresses are in agreement. Previous studies did not offer any effective test for determining critical values of damage under changing load conditions that occur in cross and skew rolling processes, among others. To compensate for this knowledge gap, researchers at the Lublin University of Technology have developed a new test consisting in rotary compression of a test-piece in a cavity between the tools, which is described in this paper. In the proposed test, a cylindrical test-piece is rolled over a cavity (impression) created by grooves on two mating tools. The cavity height is smaller than the test-piece diameter. At the critical value of the forming length, the state of stress induced thereby in the test-piece axis causes fracture. Knowing the critical forming length, it is possible to determine the critical value of damage by numerical modelling. The practical application of the proposed test is illustrated through the case of C45 grade steel subjected to forming in the temperature range 950–1150 °C. The analysis makes use of the normalized Cockcroft-Latham (NCL) criterion of ductile fracture. [ABSTRACT FROM AUTHOR]

This paper presents the results of a numerical investigation into tube flanging by extrusion with a moving sleeve. Two cases of the extrusion process are investigated, each described with a different tool kinematics. Effects of flange diameter, gap height and tool motion on the extrusion process are examined. The numerical analysis is performed on 42CrMo4 steel tubes deformed at ambient temperature. Obtained numerical results are then used to determine metal flow patterns and examine force parameters in the extrusion process, as well as to determine a technological window for the investigated method. [ABSTRACT FROM AUTHOR]

Temperatures of worker- and drone-brood rearing in various hive locations were compared in both colonies kept on small-cell combs (4.90 mm) (SMC) and standard-cell combs (5.50 mm) (STC) in two seasons. Temperatures close to the worker-brood comb placed near the rightmost storage-comb were lower than those near the worker brood in the nest centre but equal to those near the outskirt drone-brood comb (34.37-35.24°C) regardless of the month and the comb-cell size. Temperatures of the brood rearing in the SMC did not differ from those in the STC, independently on the location (center-periphery) and the brood type (drone-worker). Occasionally, they were even higher in the STC near the peripheral drone-brood comb and in the nest centre. We concluded that the drones which are involved in colony reproduction could affect its thermoregulation. The peripheral drone brood can be heated just as well as the worker brood, if the colony is strong enough and has the proper drone-worker ratio. Therefore, it is doubtful whether a higher temperature near the worker brood in the SMC limit the development of the V. destructor population. A lower temperature may not be a factor in encouraging V. destructor females to prefer trap-drone-combs for reproduction in the SMC. Strong field colonies may be especially prone to such behaviour. Therefore, temperature cannot be considered a mechanism of effective Varroa control in SMC. [ABSTRACT FROM AUTHOR]

Transparent and intumescent polymer‐silicate hydrogels were synthesized by free‐radical polymerization, in the presence of the redox initiators system (potassium persulphate/sodium thiosulphate) and cross‐linking monomer (N,N′‐methylenebisacrylamide). Hydrogels obtained in such a manner were rheologically tested and it was found that the same sample with a different sodium acrylate concentration polymerized faster when its content was lower. The spectroscopic and thermal analysis proved that the polymer combines with sodium silicate by hydrogen bonds and during thermal degradation only small polymer fragments and water molecules were released. NMR studies have shown that the content of water glass causes shorter relaxation times. Conducted fire tests showed that glass panes systems filled with the tested hydrogels meet the relevant construction standards and what is their big advantage, a thin 1 mm layer of polymer‐silicate gel is sufficient for this purpose. We believe that these results will contribute to the development of intumescent hydrogels with enhanced fire‐retardant properties. POLYM. ENG. SCI., 59:1279–1287 2019. © 2019 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The paper addresses the problem of material fracture in cross rolling processes. A new test based on rotary compression for determining limit values of the damage function after the Cockroft-Latham criterion is proposed. A FEM analysis is performed to determine the stress and strain states in a workpiece subjected to this test. The numerical results demonstrate that the axial region of the workpiece is characterized by the presence of alternating tensile and compressive stresses conducive to fracture. The distribution of the Cockroft-Latham integral in the axial region of the workpiece is determined. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to review the most recent data about corneal sub‐basal nerve plexus (SNP) evaluated with the use of corneal confocal microscopy (CCM). For this purpose, an electronic search was conducted based on PubMed and Google Scholar and Web of Science databases from 2008 up to the end of 2016. Ninety‐eight articles in English were cited, as well as abstracts in other languages, concerning the morphology and function of corneal SNP in various diseases. Changes in corneal SNP as a result of local treatment were also introduced. Figures with scans from confocal microscopy from our Department were included. The main conclusion of this review was that both corneal SNP diminishment and high tortuosity as well as low sensitivity are in principle related to the presence or level of pathology. In addition, increased nerve tortuosity may represent a morphological determinant of nerve regeneration. However, the presented literature shows that SNP changes are not characteristic for one unified corneal pathology; rather, they reflect the non‐specific pathological process present in many diseases. Future studies should use automatized biometric software and also examine the effects of new treatments on SNP. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Animal Science Biology & Bioeconomy is the property of University of Life Sciences in Lublin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper presents experimental-model research results on the process of cross-wedge rolling of an axially-symmetrical element (stepped shaft). During research plastic mass on the basis of waxes in black and white colour was used. The aim of this experimental research was to determine the best option of forming in terms of values obtained and the course of forces. Physical examination was carried out using specialist machines, i.e. model and a laboratory cross-wedge rolling mill. Experimental analysis was carried out using billets with the temperature of 15°C, whereas the actual process was carried out for billet from C45 carbon steel of temperature 1150°C. The study compared the dimensions of the components obtained during rolling tests and forming forces obtained in the result of physical modeling with forces obtained during real tests. [ABSTRACT FROM AUTHOR]

Copyright of Technical Transactions / Czasopismo Techniczne is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The subject of the study was aluminum samples of varying thickness. The aim of the study was to perform the experimental stamping process of the samples on a universal testing machine and a numerical analysis on two independent computer systems Abaqus® and Deform-3D. As part of the numerical analysis, bilinear material model was included, taking into account elastic and plastic characteristics. The study was conducted in a dynamic environment with geometric nonlinearity. The results obtained from experimental research were confronted with those obtained by FEM computer simulation. During the research, numerical model of the stamping process has been developed, which was validated with the results of experimental research. [ABSTRACT FROM AUTHOR]

Introduction and aim. Deaths due to decapitation are occasional, particularly the ones connected to traffic accidents are rarely found in forensic practice. The exact mechanism can vary depending on the method used, but the result is the same -- a separation between the head and the body. In this report, we provide an overview of the mechanisms of injury and postmortem changes, in a case of an accident where the cause of decapitation was an effect of collision with a structural element of the toboggan run. Description of the case. The decapitated body of a 15-year-old man, was found on the toboggan run. On the body, the striped skin abrasion was present on the left upper torso. At autopsy, the examination of the cervical wound showed occipital bone and the articular surfaces of the occipital condyles in the region of the great foramen, with no damage to the cricoid cartilage from the front. In terms of the neck stump, the cervical spine was visible, and the upper surface of the first cervical vertebra was exposed, with a fracture gap of the vertebral arch at the level of the pivot tooth. Histopathological examination of pulmonary tissue showed signs of acute emphysema. Multiple fractures including a fracture of the mandible and right humerus were reported. Conclusion. The injuries found at the autopsy do not make it clear from which side the force acted. Based on the edges of the neck stump that rise backward, it can be concluded that the forces that took action involved in this accident were bilateral. [ABSTRACT FROM AUTHOR]

Introduction and aim. The mechanism of motorbike accidents usually involves another road vehicle, loss of control, or collision with a fixed roadside object. However, fatal accidents involving a motorbike and a glider have not been reported in the medical literature yet. In this case, we will present the results of the autopsy, and analyse the mechanism of injuries sustained in relation to a typical motorbike accident. Description of the case. The 21-year-old man entered the airport area on a motorbike, which resulted in a collision with a glider approaching land. As a result of that accident the motorcycle driver died on the spot. At autopsy, the dissection of the skull showed subarachnoid hemorrhage. Further examination of the brain revealed the presence of liquid blood in the ventricles and flaccid choroid plexuses. During the inspection of the thorax, ecchymosis in the hilar region and ruptured bronchi were present. The pleural cavities contained liquid blood. Among the injuries to the bones of the trunk and limbs, we reported the destruction of the structures of the atlantooccipital joint, the fracture of the manubrium, numerous fractured ribs, and fractures of the humerus and femur. Conclusion. The pattern of injury reported in that case is consistent with these which are most commonly described as a motorcycle-related trauma in the literature. As it wasn't mentioned in a report whether or not the victim was wearing a helmet, we can only assume that wearing it could help with the distribution of the impact energy however it wouldn't prevent impulse transmission to intracranial structures. Keywords. Forensic Medicine, Glider, Motorbike Accident, Untypical Mechanism [ABSTRACT FROM AUTHOR]

Transparent hydrogels consisting of poly(sodium acrylate) and sodium silicate were synthesized by free-radical polymerization of sodium acrylate (ANa) in an aqueous solution of sodium silicate (i.e. water glass) with the silicate modulus (M) 2.50 and the Midafen R-102 polymer filler, in the presence of sodium thiosulphate/potassium persulphate (NTS/KPS) as the redox initiators and N, N′-methylenebisacrylamide as the cross-linking monomer. The hydrogels, obtained in this way, were rheologically tested, and also the gelling point, dependence of shear stress on shear rate, and oscillation constants were determined. The results indicated that during the cross-linking reaction, which is associated with a gradual building of the three-dimensional gel structure, the reaction mixture changes its rheological behaviour from pseudo-thixotropic at the beginning of the reaction to pseudo- anti-thixotropic in the end. Both elasticity modulus G′ and viscosity modulus G′′ during the reaction and for the cast samples after 24 h have practically the same values and the phase shift angle δ is below 20° which means that we obtained a highly elastic material. It was also found that the elasticity modulus G′ values increase with the content of sodium silicate in the sample. [ABSTRACT FROM AUTHOR]

The paper presents results of research on the assessment of the suitability of the Wierzbka I Triassic clay raw materials, which are part of the Wierzbka deposit near Suchedniów, for the production of clinker tiles obtained by pressing. Red colour clays are often used in the production technology of clinker tiles. The high content of Fe2O3 in the composition of red clays promotes the sintering process and affects the colour of the resulting material, a typical characteristic of clinker materials. The raw materials used in this technology should have good sinterability, which guarantees a material with low water absorption, high chemical resistance and mechanical strength. Samples of the raw materials were taken from three different depths of the deposit, and subjected to analysis as follows: chemical composition, phase composition (XRD, thermal analysis DSC/TG), sintering shrinkage, sintering curve and the characteristic temperatures. The analysis of the microstructure was determined using scanning electron microscopy (SEM). The X-ray and thermal analysis of the studied clays revealed the presence of clay minerals such as: illite, kaolinite, illite/smectite, but also quartz and ferruginous minerals. There was no presence of calcium carbonate in the tested samples of the raw clay, which particularly distinguishes these materials as being suitable for use in the fast firing technology of clinker tiles. Samples of the raw materials were pressed under a pressure ranging from 21 to 42 MPa and then fired at temperatures in the range 1130 to 1220°C. The obtained sintered bodies were characterized by a high degree of sintering, an apparent density of 2.31g/cm3, an open porosity of less than 2.5% and water absorption below 1.0%. The results of this study indicate a high technological value of raw materials from the Wierzbka I deposit. [ABSTRACT FROM AUTHOR]

The paper presents the results of research on the influence of the granulometric composition on the rheological properties of granulates from soft waste produced in the manufacturing of ceramic tiles using the Lamgea and Continua methods in terms of the possibility of their reuse. The composition of the granulates was modified by removing individual grain fractions in three measurement series. Comparatively, the measurement samples for the production granulates were prepared in the same way. Microscopic observations and granulometric analysis showed significant differences in the grain shape and grain size distribution of granulates. The soft waste granulates also showed much worse flow ability than the production granulates. It was shown that the removal of the smallest fractions significantly improved the rheological properties of soft waste granulates. This tendency was also observed in the case of measurements of changes in the bulk density. A Brookfield powder analyzer was used for rheological tests, and a flow analysis was performed using the numerical Jenike classification. [ABSTRACT FROM AUTHOR]

The article presents the results of model tests with which a comparative analysis of two methods of ball separation during the skew rolling process was carried out. A verification of the results obtained in the physical modelling process with the results obtained in the real process of skew ball rolling was also carried out. During the physical modelling, the effect of changing the ball separation method on the quality of the products obtained, variations in maximum torque values and maximum radial forces were analyzed. In the case of real tests, the results were verified with the results of physical modelling, in which the surface quality and torque values for one of the tool sets were compared. Physical modelling was used to verify the differences between the two methods of ball separation. Commercial plasticine based on synthetic wax from the manufacturer PRIMO was used as a model material for physical analysis. The plasticine used for testing was cooled to 0 °C and the cooling process took 24 h. The tools used for the physical modelling were 3D printed and the material used was ABS. The method of physical modelling using plasticine as a model material allows for a correct analysis of hot metal forming processes. [ABSTRACT FROM AUTHOR]

Simple Summary: The aim of our study was to test the immunostimulating effect of a diet with hemp extract on the resistance of the honey bee (Apis mellifera). The experiment compared the effect of supplementation between the bees receiving the extract in the form of a mixture with sugar syrup and on the strip with the extract, compared to the bees that had no contact with substance. In order to determine this effect, the biochemical indicators were analyzed: the proteolytic system (proteases, protease inhibitors, total protein concentration) responsible for the fight against pathogens/parasites, biomarkers (ALT, AST, ALP), and the basic components of metabolism (glucose and urea concentrations). Parameters were determined in the hemolymph of 2- and 7-day-old workers. Hemp extracts caused an increase in the protein concentrations. Regardless of the method of administration, proteases decreased. Protease inhibitors increased, except supplementation on strips where the activity decreased. The biomarker activities increased in the control group and workers feeding extract in syrup and decreased in workers supplemented with the extract on strips. The results of the metabolic component were as follows: glucose and urea concentrations indicate that the extract will not adversely affect metabolic changes in the insect's organism. Hemp extract improves the natural immunity of bees. In the study, we assessed the effect of hemp extract on activities of resistance parameters and the metabolic compound concentration in adult workers' hemolymph. Bees were divided into the following groups: (1) control group fed with mixture of sugar and water-glycerine solution, (2) experimental group with pure sugar syrup and inside with cotton strips soaked with hemp extract, (3) experimental group with a mixture of sugar syrup with hemp extract. Hemp extracts caused an increase in the protein concentrations and reduced the protease activities regardless of the administration method. The protease inhibitor activities were decreased only in the group that received hemp extract on the strips. The biomarker activities (ALP, ALT, AST) increased from the control group and workers feeding extract in syrup and decreased in workers supplemented with the extract on strips. In young, 2-day-old workers, the glucose concentration was higher in the groups feeding with the extract than in the control. Hemp extract influenced an increase in urea concentrations in workers' hemolymph in comparison with the control. The hemp supplementation positively influences the immune system of workers, and the appropriate method of administration may be adapted to the health problems of bees. [ABSTRACT FROM AUTHOR]

Simple Summary: Efficient and proper functioning of processes within living organisms play key roles in times of climate change and strong human pressure. In insects, the most abundant group of organisms, many important changes occur within their tissues, including the fat body, which plays a key role in the development of insects. Fat body cells undergo numerous metabolic changes in basic energy compounds (i.e., lipids, carbohydrates, and proteins), enabling them to move and nourish themselves. In addition to metabolism, the fat body is involved in the development of insects by determining the time an individual becomes an adult, and creates humoral immunity via the synthesis of bactericidal proteins and polypeptides. As an important tissue that integrates all signals from the body, the processes taking place in the fat body have an impact on the functioning of the entire body. The biodiversity of useful organisms, e.g., insects, decreases due to many environmental factors and increasing anthropopressure. Multifunctional tissues, such as the fat body, are key elements in the proper functioning of invertebrate organisms and resistance factors. The fat body is the center of metabolism, integrating signals, controlling molting and metamorphosis, and synthesizing hormones that control the functioning of the whole body and the synthesis of immune system proteins. In fat body cells, lipids, carbohydrates and proteins are the substrates and products of many pathways that can be used for energy production, accumulate as reserves, and mobilize at the appropriate stage of life (diapause, metamorphosis, flight), determining the survival of an individual. The fat body is the main tissue responsible for innate and acquired humoral immunity. The tissue produces bactericidal proteins and polypeptides, i.e., lysozyme. The fat body is also important in the early stages of an insect's life due to the production of vitellogenin, the yolk protein needed for the development of oocytes. Although a lot of information is available on its structure and biochemistry, the fat body is an interesting research topic on which much is still to be discovered. [ABSTRACT FROM AUTHOR]

This study investigates the problem of material fracture in cross wedge rolling (CWR). It was found that this problem could be analysed by means of well-known phenomenological criteria of fracture that are implemented in commercial FEM (Finite Element Method) simulation programs for forming processes. The accuracy of predicting material fracture depends on the critical damage value that is determined by calibration tests in which the modelled and real stresses must be in good agreement. To improve this accuracy, a new calibration test is proposed. The test is based on the CWR process. Owing to the shape of the tools and test piece used in CWR, the forming conditions in this process deteriorate with the distance from the centre of the test piece, which at a certain moment leads to fracture initiation. Knowing the location of axial crack initiation in the specimen, it is possible to determine the critical value of material damage via numerical simulation. The new calibration test is used to determine the critical damage of 42CrMo4 steel subjected to forming in the temperature range of 900–1100 °C. In addition, 12 criteria of ductile fracture are employed in the study. The results show that the critical damage significantly increases with the temperature. [ABSTRACT FROM AUTHOR]

This work presents a summary of research on concrete fireplace materials made of various mineral aggregates and enriched with steel and organic fibers. To determine the optimal applications of such concretes, their ability to accumulate heat and their other physicochemical parameters were tested and analyzed. Studies on the behavior of concrete materials during cooling are reported, and the ability of such materials to accumulate heat is evaluated using calculations. In addition, tests were performed on the loss of mass during heating, as well as on the mechanical bending strength and microstructures of these materials. Studies have shown that the behavior of concrete materials at high temperatures can be modified and adapted for specific purposes. The addition of fibers to concrete improves both the mechanical properties of mortars and the heat flow in concrete materials. [ABSTRACT FROM AUTHOR]

The present article reports selected results of a preliminary study of the process of skew rolling of bimetallic rods. The experiments were conducted using a numerically controlled three-roller skew rolling mill. During the tests, bimetallic rods were rolled from billets whose cores and outer sleeves (bushings) were made of different types of steel. The results demonstrate that the proposed method can be successfully used in the production of bimetallic rods. However, proper fastening of the two materials depends on the geometrical parameters of the billets, and the quality of bimetallic rods depends on the heating method used. When the rods are heated without protective atmospheres, the surface layer of the core gets decarburized and the surfaces of the materials being joined together are oxidized, which hinders the welding process and adversely affects the physical and chemical properties of such products. The results of numerical modeling indicate that the material near the surface tends to flow, which may have a negative impact on the welding process. In addition, the distribution of stress in the tool–workpiece contact zone may make welding of the materials difficult. The results reported in this paper are preliminary and constitute a prelude to a more detailed analysis of bimetallic rod rolling. [ABSTRACT FROM AUTHOR]