The results of microstructura l analysis, short-term and long-term strength tests of modified sparingly alloyed refractory alloy of 32%Cr-43%Ni and its welded joints are presented. A quantitative analysis of the dispersed phases in the initial state and after long-term strength tests has been carried out. It is shown that the network of carbide-intermetallic precipitates persists after long-term strength tests at a temperature of 1150 °C. This ensures the ability of the developed alloy and its welded joints to withstand high-temperature creep for a long time. It has been established that after long-term strength tests at a temperature of 1150 °C, niobium carbide particles present in the base metal and weld metal are almost completely transformed into an intermetallic phase based on Cr-Ni-Si-Nb-N. The penetration of atmospheric nitrogen into the metal stimulates this process.
The presented scientific research work is dedicated to solving the problem of obtaining polymer composite materials with various superior operational properties based on polyolefins and a number of natural mineral rocks characterized by their corresponding characteristics, and investigating the application possibilities of the created materials. In this regard, local natural mineral resources are prepared for research in laboratory conditions through technological processes and mixed with a polymer matrix using a physical-mechanical method. The resulting mixture is brought to a ready state for research and is introduced into the process. Composite samples created on the basis of polyolefin and mineral rock are sent for research in accordance with different ratios of the components that make up the composite. The goal is to find the optimal ratio and determine the material that reflects higher quality criteria. Research conducted in this direction has yielded positive results. Research work that meets the requirements of modern chemical science can be considered satisfactory from an ecological and economic perspective.
A detailed examination of the structure of the high-entropy alloy Al0.5CoCrCuFeNi at room temperature was carried out using different methods of optical microscopy, electron microscopy and X-ray structural analysis techniques. Numerical estimates of the dislocation density ∼5⋅1015 m−2, the mean size of the ordered (crystalline) domains ~18 nm and lattice micro strain ∼3⋅10−3 were obtained through Williamson-Hall analysis of XRD patterns. The estimates of the dislocation density were found to correlate with the estimates of the total length of dislocation segments per unit volume, which effectively interact with elastic vibrations of the sample ∼4⋅1013 m−2, as previously determined from acoustic relaxation measurements. This is consistent with the idea that a significant portion of dislocations are concentrated in grain boundaries, and only dislocation segments located inside grains and having a favourable orientation with respect to the direction of sound wave propagation can effectively interact with cyclic deformation of the sample.
This study investigates the mechanical behaviour and optimization of rigid flange couplings operating under two distinct environmental conditions: normal atmospheric air and high-pressure oil surroundings. A Taguchi L9 orthogonal array was employed to evaluate material combinations for the shaft, flange, and bolt based on four mechanical responses: total deformation, equivalent stress, shear stress, and normal stress. Analysis of variance (ANOVA) and regression modelling were used to identify significant parameters, with flange material consistently emerging as the most influential factor. Desirability analysis was conducted to determine the optimal material configurations for each environment. Under atmospheric conditions, the combination of C30 shaft, FG200 flange, and C45 bolt achieved a composite desirability of 0.6667. In high-pressure oil conditions, the optimal configuration was C45 shaft, FG260 flange, and C45 bolt, with a desirability of 0.7185. These optimal settings, not present in the original matrix, were independently validated using finite element analysis (FEA). The comparison between regression predictions and FEA results showed strong agreement, with a maximum percentage error of 6.02%, within acceptable engineering limits. This study confirms that environmental pressure significantly influences coupling performance and that material selection should be tailored accordingly. The integration of statistical optimization and simulation offers a robust framework for designing couplings in pressure-sensitive applications.
Chronic obstructive pulmonary disease (COPD) is a leading cause of global morbidity and mortality, characterized by progressive airway and alveolar remodeling. The disease pathogenesis is commonly driven by chronic environmental insults, leading to airway obstruction, emphysema, and chronic bronchitis. This review synthesizes emerging evidence that altered epithelial cell behavior and dysfunctional epithelial-mesenchymal interactions serve as pivotal drivers of COPD pathogenesis, orchestrating failed repair and structural degeneration. We detail how altered responses of airway (ciliated, club, basal, goblet) and alveolar (AT1 and AT2) epithelial cells lead to cellular senescence, metaplasia, defective regeneration, and barrier disruption, acting as primary instigators of pathogenesis. We also summarize current knowledge on the mechanisms of activation and pathogenic role of mesenchymal cells, which drive peribronchiolar fibrosis, alveolar destruction, and metabolic reprogramming, alongside the compromised reparative function of mesenchymal stem cells (MSCs). We emphasize how distinct mesenchymal niches (e.g., PDGFRαPos MANCs, FGF10Pos lipofibroblasts, SFRP1Pos fibroblasts) and distinct epithelial stem/progenitor subpopulations critically contribute to pathogenesis. Key signaling pathways—including FGF10/FGFR2b, WNT, Hippo, NOTCH, and TGF-β—mediate epithelial-mesenchymal transition (EMT), stem cell niche function, and structural remodeling. By dissecting how epithelial injury responses and mesenchymal niche failure collaboratively drive COPD progression, we identify actionable targets to disrupt pathogenesis and restore endogenous repair. We propose targeting EMT, including inhibiting EMT/fibrosis, promoting alveolar regeneration, MSC-based therapies, exosome-delivered biomolecules, and precision cell transplantation strategies, as promising future therapeutic strategies.
