One of the key principles of rational environmental management is finding ways to recycle by-products. Gypsum-bearing waste such as phosphogypsum (PG) is a large-scale waste. Resolving the problem of its accumulation is a global challenge. Phosphogypsum is a by-product of orthophosphoric acid and phosphate fertilizer production. PG mainly consists of calcium sulfate dihydrate and can be considered as an alternative to natural gypsum rock in gypsum binder production. However, previous studies have shown that the structural and morphological features of PG particles are the cause of the high water demand of phosphogypsum binders (PGB) and the resulting low physical and mechanical properties of consolidated phosphogypsum paste. This study examined the possibility of increasing PGB efficiency by increasing their dispersion, including by grinding. The study found that grinding PGB after calcination generally improves its properties and can be recommended as an effective manufacturing technique for reducing the impact of the structural and morphological properties of phosphogypsum from various sources on the quality of the final product. The compressive strength of PGB after grinding to a specific surface area of ≈480 m2/kg ranged from 3.06 to 5.41 MPa after 2 hours of mixing and from 6.78 to 13.68 MPa in the dry state.

In the present work, modeling of hoop stress in the defect-free structural steel pipe was done under the combined effect of internal hydrostatic pressure and temperature difference using finite element analysis (FEA) and response surface methodology (RSM). The FEA simulation was done on the quarter-ellipsoidal sections of the structural steel pipe specimen using ANSYS 2022 R1 software. The calculated hoop stress using FEA was in agreement with the analytical solution of hoop stress. The thermodynamically induced hoop stress due to the temperature difference (without internal hydrostatic pressure) exhibited a compressive state at the inner wall and a tensile state at the outer wall of the specimen. This compression-tension state also provided a thermodynamic situation at which the total hoop stress becomes null at the neutral axis. However, when the specimen was subjected to internal hydrostatic pressure (in addition to the temperature difference), the initial neutral axis received a thermomechanical hoop stress of a tensile nature. A drop in the burst pressure from 11.5 MPa to 9.9 MPa was observed when the steel pipe was subjected to a maximum temperature difference of 40 °C. A new analytical equation for thermomechanical hoop stress was developed using RSM modeling by considering independent variables as the normalized position in the wall (ṝ), internal hydrostatic pressure (P), and temperature difference (ΔT). The developed analytical equation envisages that the interacting effect of independent variables ṝ(ΔT) was maximum, followed by the interacting effect of ṝ(P). An optimum internal hydrostatic pressure of 7.43 MPa was calculated considering the flow stress of the material for all possible combinations of the other two independent variables (ṝ and ΔT). Furthermore, at the optimum ΔT of 39.65 °C, the interacting effect of the ṝ(P) provided contour-curvature plots, both below the yield strength and endurance limit, considering different combinations of normalized position in the wall and internal hydrostatic pressure.

The current work presents a finite element analysis (FEA) based investigation of the structural steel pipe with internal corrosion defects. A total of 27 different geometrical conditions for internal corrosion defect were considered using 3 different internal pressures of 2.2 MPa, 4.5 MPa, and 6 MPa. The validation of the FEA model was carried out using the analytical solution for failure pressure using radial and hoop stresses. The failure pressure of the uncorroded pipe was 11.5 MPa. In contrast, for pipe with internal corrosion defect having the largest defect depth (1.7 mm), largest length (454 mm), and sharpest geometry (width of 26 mm), the failure pressure from FEA was 6 MPa. The remaining strength at this boundary condition was 0.521. The radial stress influences the strain in wall thickness which was 8.8 mm and much less as compared to other dimensions of pipeline which diminishes the material's ability to resist the failure pressure. The Von-Mises stress accumulation inside the interface increases the stress intensity (K) distribution at the vicinity of the internal corrosion defect geometry vis-à-vis lowers the K-distribution just outside of the internal corrosion defect. The largest factor of safety (FOS) of 2.11 was obtained at threshold boundary conditions considering fatigue limit as the optimum stress. It is then suggested that the FOS for the "break-before-leak" leak model can be anywhere between 2.11 to 1.45 and hence the pipeline cannot burst into rapture.

Hot rolled 40Cr and W6Mo5Cr4V2 steels were diffusion-welded by using a 4-staged process including uniaxial 50 kN compression at 1200 oC in 10^-5 mbar vacuum with following cooling down to room temperature. Structural 40Cr and high-speed tool W6Mo5Cr4V2 steels are dissimilar, since they are different (i) in content of host Fe element and alloying Cr, W, V, Mo elements, (ii) in phase composition (40Cr steel is single-phased and W6Mo5Cr4V2 steel is multi-phased), (iii) in microstructure (homogeneous inclusions-less microstructure is characteristic for 40Cr steel, composite microstructure consisting of matrix Fe-based phase with metal (W, V, Mo) carbides is characteristic of W6Mo5Cr4V2 steel), and (iv) in grain structure (40Cr steel is coarse-grained with grain ~100 µm size and W6Mo5Cr4V2 steel is fine-grained with grain size of several µm). Phase composition, microstructure and grain structure of the steels are retained after welding. Diffusion redistribution of Fe, Cr, W, V, Mo atoms results in forming the diffusion zones with different widths (several µm for W, V and Mo, ~25 for Cr and ~15 µm for Fe). Resulting concentration Cr profiles are typical for diffusion from limited sources and could be satisfactorily described by diffusion coefficient equal to ~1.1∙10^-14 m²∙s^-1 (the coefficient is weighted over the entire temperature range from 1200 oC to room temperature). Within the diffusion Cr and Fe zones, the Vickers microhardness decreases from ~2000 HV (for W6Mo5Cr4V2 steel) to ~530 HV (for 40Cr steel). During room-temperature tensile tests, the diffusion-welded steels were always fractured not in the diffusion joint but in 40Cr steel.

The article assesses the structural strength of sample materials destroyed on standard equipment for determining the mechanical properties of materials. The distribution of mechanical stresses of laboratory disk samples with stress concentrators in the form of grooves on the support surfaces was analyzed. It was revealed that the disc truncation along the two symmetrical chords allows for varying the type of stress state in the sample and intensity of stresses in the working zone. The problems of the linear theory of elasticity were solved for samples with different degrees of disc truncation and with different geometric parameters of the groove profile. The analysis of disk deformation showed that these laboratory samples can be used in simulating the type and level of stress-strain state of various parts of machines and mechanisms. This factor significantly expands the possibilities for assessing the structural strength of materials during laboratory studies of the materials. It was revealed that the type of stress-strain state (SSS) plays a role in localizing the sources of destruction of highly loaded structural elements made from structural carbon steel St45. The results can be used both for the experimental assessment of the structural strength of materials and for constructing limit state equations corresponding to a SSS level and type.

Issues of industrial waste recycling are very relevant for the entire global scientific community. The search for technological solutions that would allow the production of high-quality materials using industrial waste will not only reduce the environmental load, but also expand the raw material base for the production of gypsum materials. The study examined the possibility of improving the surface quality of molded gypsum samples by replacing the metal mold with a plastic one and introducing a surfactant into the raw mixture. As a result of the research, it was found that the use of a surfactant and a plastic mold allows to avoid defects on the surface of the samples. At the same time, the use of a plastic mold, which has low adhesion to the citrogypsum-based binder, helps to reduce the amount of adhesion friction and optimize the raw mixture compaction process. This makes it possible to obtain samples with improved physical and mechanical characteristics (compressive strength increases by 30–85.5%, average density - by 1.7–2.7% and water absorption decreased by 1.7–16%) or lower consumption of binder up to 20% compared to samples prepared in metal mold.

The main aim of this study is to assess the effectiveness of entrepreneurship quality education in higher education institutions in Indonesia on entrepreneurial goal intentions with the mediating effect of entrepreneurial training. The research followed the quantitative research design as the researcher collected data based on numeric facts. The sample size was 314 participants and a test was carried out on Smart PLS. The results were based on the measurement model to test the factor loadings, validity and reliability, path assessment, and the blindfolding technique which were mainly used for assessing the predictive relevance of the model. The findings of the study suggest that entrepreneurial training mediates entrepreneurship quality education programs in higher education institutions in Indonesia with entrepreneurial goal intentions.

This research paper aims to find out the impact of entrepreneurial education and entrepreneurial training on the performance of women entrepreneurs in Indonesia by considering the moderating role of personal characteristics. A quantitative research method has been adopted in this research. The instrument used for collecting primary data was a Likert-scale based survey questionnaire which included close-ended questions. A sample of 376 women was drawn from the population. The statistical analysis has been carried out via Smart PLS where structural equation modelling has been used. There are different techniques used to effectively interpret the data and test the hypothesis of the research paper including confirmatory factor analysis, discriminant validity, and path analysis. The current study confirms that there is a significant and positive impact of entrepreneurial education on the performance of women entrepreneurs. However, the study contradicts the findings of the prior studies when it was determined that there had been no significant impact of entrepreneurial training on the performance of women entrepreneurs in the context of the Indonesian entrepreneurial sector. The moderating effect of personal characteristics for this research was found to be insignificant.

This study presents data on the development and research of cryogenic-vibration grinding process modes which would ensure an efficient grinding process of complex composite systems with a high degree of heterogeneity of components in their composition of products such as fluoroplast, bismuth oxide and tungsten carbide. The general regularities of low-temperature processing and grinding of non-degassed elastomers are established. A method has been tested that establishes the regularities of cryogenic grinding and ultrasonic homogenization of a complex mechanical system, the microstructure and dispersed compositions of the ground material have been determined.

Gold and silver nanoparticles are easily synthesized and the most effective nanostructures in clinical practice. Their optical properties, ease of synthesis, colloidal stability and the ability to form any surface for easier conjugation with biological particles, the ability to individual multiple use, make them especially important in oncology. Gold and silver nanoparticles are capable of providing targeted drug delivery, which depends on the photothermal, photodynamic, and antiangiogenic properties of the metal. Due to their exceptional properties, these nanoparticles are considered as a potential tool for the diagnosis of various types of cancer and drug delivery. The non-toxic and non-immunogenic nature of gold and silver nanoparticles, as well as their high permeability and retention effect, provide additional advantages, allowing drugs to easily penetrate and accumulate at tumor sites. The effectiveness of precious metal nanoparticles as radiosensitizers, dose enhancers and contrast agents is gaining increasing recognition. An important problem associated with the use of biogenic metal nanoparticles is the study of their genotoxicity, since they play an important role in the initiation and progression of abnormalities, including genetic ones.