Search Results (53)

Early detection of acute lung injury (ALI) remains challenging, as conventional diagnostics rarely capture initial molecular changes. We therefore examined whether extracellular vesicles (EVs) in bronchoalveolar lavage fluid (BALF) can detect early regional injury and distinguish initial stress mechanisms in a porcine ALI model. Unilateral ALI was induced using Triton X-100, followed by six hours of mechanical ventilation with either fixed positive end-expiratory pressure (PEEP) at 5 cmH₂O or transpulmonary-pressure (TPP)-guided PEEP. Spatially separated BALF sampling allowed direct comparison between injured and contralateral mechanically stressed lungs. EV concentration and size distribution were quantified by nano-flow cytometry, while vesicular identity was confirmed by transmission electron microscopy and tetraspanin dot blot analyses. Furthermore, EV metrics were related to corresponding histologic injury scores. Across both PEEP strategies, EV concentration was markedly higher in both directly injured and contralateral mechanically stressed lungs compared with sham controls, indicating alveolar stress beyond the primary injury site. Median EV size differed significantly by injury type and correlated inversely with histologic injury, particularly with alveolar neutrophil infiltration. BALF-derived EV concentration and size may therefore provide complementary, spatially resolved molecular readouts of early ALI. Full article

The paper is focused on the problem of increasing the reliability of determining the critical speed of railway vehicles during measurements in bench tests, due to the difference in the geometry of the contact interaction in the “wheel-roller” and “wheel-rail” systems. It is shown that existing approaches in dynamic stability analysis and the processing of measurement signals do not consider the systematic influence of equivalent conicity on the measurement results, which leads to a shift in the assessment of the threshold for loss of stability even with the high accuracy of the measuring equipment. An information-measuring approach is proposed, which is based on an analytical description of the relationship between the equivalent conicity of the wheel/rail contact and the critical speed. A generalized error model is developed integrating geometric, metrological and random components. A method for correcting the results of bench tests based on a coefficient considering the ratio of equivalent conicities is also proposed. It was found through the results of the research that neglecting the geometric mismatch of the contact interaction leads to an error in determining the critical speed at the level of 8 to 15%, while the application of the proposed approach reduces it to less than 1 to 2%. Additionally, frequency analysis of the oscillatory process was used. It allowed us to identify the critical mode of the frequency range of about 8 Hz and to establish its connection with the critical speed of movement. It was experimentally confirmed that the corrected results correspond with the calculated values within 1%. The obtained results provide an increase in the metrological consistency of bench and operational studies, expand the possibilities of interpreting test results and can be used in the development of methods for diagnostics, certification and prediction of the limit modes of operation of railway vehicles. The proposed approach provides increased reliability in determining the critical speed during bench tests and it can be used for analytical compensation of a systematic error without upgrading the test equipment. Full article

The objective of this study is to develop a physical model of a prestressed reinforced concrete railway sleeper, to construct a corresponding finite-element model, and to compare the experimental and numerical results. During operation, many of them sustain damage due to cracks. The article deals with the crack resistance of sleepers, specifically the impact of anchoring on reinforcement. Physical models of concrete sleepers were designed and fabricated; they included specimens with non-anchored or anchored reinforcement. Their finite-element models were constructed, and both computational and full-scale experiments were carried out; they also included their loading to failure. It is found that the anchoring of reinforcement does not improve the crack resistance or strength of the models, and even leads to a slight reduction in their properties. It has therefore been found that the anchoring of reinforcement does not improve the resistance of sleepers up to the formation of transverse cracks in the under-rail and mid-section areas; however, it can be considered as a technological measure, as well as a measure for protecting the ends of rebars from contact with the external environment to prevent leakage currents from flowing through them. The results obtained make it possible to design sleepers with anchored reinforcement to achieve the required crack resistance. Full article

The article proposes an integrated approach to prepare passenger cars for operation considering resource constraints and seasonal fluctuations in passenger traffic. The study is based on an analysis of the operational data on the volume of passenger car washing and water consumption during the period 2017–2024. The work uses methods of statistical analysis, regression modeling and numerical optimization. A close correlation between the number of passenger cars in the train and water consumption has been established, which allowed the formation of the corresponding regression dependencies and their integration into the structure of the optimization model. A mathematical model has been developed considering the time, resource and labor parameters of the process of preparing passenger vehicles and ensures a rational allocation of resources. The objective function combines time costs and the cost of processes using weighting factors, and the system of constraints considers technological, resource and organizational aspects. The model is adapted to variable operating conditions and provides for the possibility of scenario analysis. The results of the study showed that the use of automated passenger car wash complexes allows the reduction of water consumption by 10–12% and reduces the duration of washing by up to 20%. The use of the optimization model ensures a reduction of the total time for train preparation by 18–22% and a reduction in operating costs by 12–16%, which indicates an increase in the efficiency of resource use. Additionally, it was found that the introduction of automated technologies contributes to the reduction of the negative impact on the environment by reducing water consumption and reducing the level of wastewater pollution. The results obtained confirm the effectiveness of the proposed approach and the feasibility of its application in passenger cars’ maintenance systems. Full article

The work presents a thermodynamic analysis of phase equilibria in the subsolidus region of the three-component oxide system CoO–BaO–Fe₂O₃. The relevance of the study is due to the growing interest in ceramic ferrites with specified magnetic and electromagnetic properties, which are used in the creation of functional composite materials. The aim of the work was to establish thermodynamically stable binary and ternary phase combinations in the CoO–BaO–Fe₂O₃ system based on the analysis of solid-phase exchange reactions without taking into account ternary oxide compounds. This analysis represents a simplified thermodynamic model that considers only binary oxide compounds and excludes ternary ferrite phases. Thermodynamic calculations of Gibbs energy changes for model reactions of the type “2 = 2” were performed in the temperature range 1000–1800 K using the temperature dependencies of the enthalpies and entropies of compounds. To resolve contradictions arising from the analysis of the stability of individual conjugates, the method of conjugating exchange reactions with a transition to “3 = 2” type interaction mechanisms was applied. As a result of triangulation, nine thermodynamically stable binary combinations of compounds and ten stable triple phase combinations corresponding to elementary triangles of the subsolidus structure of the system were identified. The predisposition of the CoFe₂O₄–BaFe₁₂O₁₉ compound to destabilization is demonstrated, and its structural and phase stabilization due to the formation of an equilibrium three-phase combination of CoFe₂O₄–CoO–BaFe₁₂O₁₉ is substantiated. A general rule has been formulated for analyzing the thermodynamic stability of phase combinations in exchange reactions of the type “3 = 2”. The results obtained provide a physicochemical basis for predicting the phase composition of ferrite materials and composites in any concentration range of the CoO–BaO–Fe₂O₃ system and can be used in the development of technologies for the reaction synthesis of new ceramic ferrites. Full article

The transport sector requires compact, reliable, and energy-efficient power units for modernization of road, rail, maritime, and aerial systems. Conventional piston and rotary machines often face limitations related to vibration, sealing losses, and manufacturing complexity. This study investigates birotor machines (BM), a class of positive-displacement devices combining synchronized rotation of the rotor and housing. This configuration ensures smooth kinematics, near-complete dynamic balance, and simplified design. The working principle enables continuous volumetric transformation with reduced friction and leakage, enhancing efficiency and durability. Using generalized mathematical models (GMM) developed through statistical experimental design, optimal geometric parameters were determined with a root-mean-square error below 3%. A prototype birotor compressor (BC) designed for subway rolling stock achieved equivalent output performance (0.43 m³/min at 0.8 MPa) with 82% efficiency and a mass reduction from 130 kg to 32 kg. Comparative simulations and preliminary testing of BM-based internal combustion engines (BRICE) demonstrated 3–4 times smaller and lighter units with improved reliability and environmental characteristics. The results confirm that BM technology provides a feasible and manufacturable alternative to conventional designs, suitable for integration into next-generation transport and unmanned vehicle systems. Full article

This paper contributes to the knowledge of binderless tungsten carbide (WC), which attracts the attention of many engineers and scientists for its superior properties, but its application is limited due to difficulties with the consolidation of initial powders. In the present study, the microstructure and mechanical properties of binderless WC, sintered with the electroconsolidation technique from the initial powder of a grain size of 100–200 nm, were investigated. The material was compared with nWC sintered with the same method from a nanopowder with particles of size ca. 70 nm. The binderless μWC demonstrated hardness of HV = 30.06 ± 0.09 GPa, which is almost 14% higher than that of nWC, but its fracture toughness was lower (K_IC = 6.59 ± 0.46 MPa·m^1/2 under 1 kg load). These differences can be attributed to the improved homogeneity of the μWC microstructure, where no large agglomerates appeared to be present in nWC. The measured plastic properties, with no signs of brittle fracture, further confirm the applicability of the binderless WC under contact stress conditions. Full article

In this paper, we analyze the concept of need that we find in the foundation of Carl Menger’s value theory to then confront it with such heterogeneous philosophical theories as Ludwig Feuerbach’s dialectic of feelings, Arnold Gehlen’s notion of humans as defective beings, and Ortega y Gasset’s theory about the role of technology and production in the human project. In general terms, these authors worked with the same notion of need that Menger used, but from an anthropological perspective. In this sense, we hypothesize that, despite belonging to heterogeneous philosophical traditions, the authors above can help us fully understand the concept of need in Menger, a notion that he did not develop in depth. In doing so, we attempt to show that this implicit content prefigures an anthropology that conceives human beings as primarily active and axiological beings. With this, we also aim to show the hermeneutical richness of the concept of need, as well as its relevance for creating interdisciplinary connections for future research. Full article

This study examines the influence of vanadium carbide (VC) on the physical and mechanical properties of SiC–VC composites fabricated by a modified spark plasma sintering (SPS) method at a uniaxial pressure of 45 MPa. It was found that the addition of 40 wt.% VC into the SiC matrix led to a substantial reduction in porosity from ca. 30% to less than 8.2% and caused enhancement of the properties. Fracture toughness increased from 2.9 to 7.0 MPa·m^1/2, and hardness rose from 2.9 to 22.6 GPa. In the SiC–VC system, vanadium carbide acted as a grain growth inhibitor and particulate reinforcement. A sintering temperature increase from 1900 °C to 2000 °C resulted in a ~70% improvement in hardness and a ~50% gain in fracture toughness. The results highlighted the critical balance between densification parameters and microstructural stability. Utilization of n-dimensional vector space of material features, Mahalanobis distance, and Pareto trade-off optimization helped to describe the features of the newly obtained composites and to optimize the manufacturing process. Full article

This study deals with the problem of uneven wear of brake pads of wagons caused by a set of structural, dynamic, technological and operational factors. It has been found that an uneven distribution of the brake pad pressure force leads to higher maintenance costs and lower braking efficiency. The main causes of uneven wear are worn kinetostatic units, differences in the geometric parameters of pads, and imperfections in the lever transmission design. A method for optimizing the distribution of the pressure force using weight coefficients and the Lagrange function has been developed; it reduces the uneven wear of brake pads to 8–10% compared to that of a typical wagon bogie brake system, which is 20–35%. The experiments conducted have shown that for a mileage of 74,400 km and with the air distributor in empty mode, the wear of the pads is 19.6–28 mm, while in the loaded mode it amounts to 27.53–38.04 mm. The stress state of brake pads was determined with consideration of the weight coefficients. It was found that for abnormal wear of brake pads, their strength is not observed. The strength of the wheel when interacting with an abnormally worn pad has also been assessed. The resulting stresses are 1.5% higher than those that occur when the wheel interacts with the pad with nominal dimensions. The results of the research will contribute to the database of developments to be used for designing of modern structures of tribotechnical pairs of rolling stock and increasing the efficiency of railway transport. Full article

The kinetic regularities of the electrօspark sintering of SiC–TiC, SiC–VC composites at a pressure of 45 MPa and the temperatures of 1900 and 2000 °C have been established. At the first stage of the composite compaction process, the addition of TiC, VC impurities in the amount of 20 vol.% to silicon carbide with a dispersion of 2 μm increases the compaction rate by 1.3 and 1.1 times, respectively, and the addition of Ti, V carbides in the amount of 40 vol.% increases the compaction rate by 1.7 and 1.2 times, respectively. At the second stage of the compaction process, when Ti, V carbides are added in the amount of 40 vol.%, the compaction increases from 70% in silicon carbide to 99.9% in the 60SiC–40TiC composite and 91.2% in the 60SiC–40VC composite. Solid-phase sintering in composites with an admixture of titanium carbide is better than in composites with an admixture of vanadium carbide due to an increase in interaction at the phase boundaries: the interaction zone increases from ~1.0 μm at the boundaries of silicon carbide and vanadium carbide grains to ~1.5 μm at the boundaries of silicon carbide and titanium carbide grains. Full article

This research highlights the results of a comprehensive study of the efficiency of modernized brake systems operation of freight wagons. The inspection of the modernized elements of the lever brake system of bogies and the measurement of the wear parameters of composite brake pads during each cycle of the experimental wagons in the interval of mileage from 2.1 to 197.8 thousand km were carried out. A statistical approach was used to study the wear parameters of brake pads of modernized bogies brake systems determined during operational studies. This allowed appropriate dependencies of brake pad wear to be obtained. Based on the research results, a regression model was developed. This makes it possible to predict the residual wear resource of composite brake pads with modernized braking systems of bogies for the entire inter-repair period of operation of freight wagons guaranteed by the wagon repair company. The peculiarity of the model is that it considers the total and additional mileage of the freight wagon. This makes it possible to more accurately predict the residual lifetime of composite brake pads. It was established that, under the condition of uniform wear of brake pads, the average mileage of a freight wagon during the use of modernized brake systems of bogies can reach up to 284.57 thousand km, which increases the resource of composite pads’ wear approximately by 2.59 times. The generated model was verified by the F-criterion. Approbation of experimental devices for uniform wear of composite pads in operation established that measures to modernize brake systems of freight wagons ensure the reliable and efficient operation of the brake lever system as a whole. Full article

This article revisits Feuerbach’s “break with speculation” in the early 1840s in light of issues raised by the original Pantheism Controversy, initiated in 1785 by the publication of Friedrich Heinrich Jacobi’s Letters on the Doctrine of Spinoza. The article first describes the concerns underlying Jacobi’s repudiation of Spinozism, and rationalism more generally, in favor of a personalistic theism that disclaims the possibility of philosophical knowledge of God. It goes on to reconstruct Hegel’s alternative to Jacobi’s famous salto mortale before considering how Feuerbach’s critique of Hegel’s philosophy of religion, as well as the personalism of the so-called Positive Philosophy (inspired by the late Schelling), was influenced by both Spinoza and Jacobi in ways that have not yet received sufficient attention. Full article

In this study, hydrothermal co-liquefaction of restaurant waste for biocrude production was conducted. The feedstock was resembled using the organic fraction of restaurant waste and low-density polyethylene, polypropylene, polystyrene, and polyethylene terephthalate, four plastic types commonly present in municipal solid waste. Using design of experiment and a face-centered central composite design, three factors (feedstock plastic fraction, temperature, time) were varied at three levels each: feedstock plastic fraction (0, 0.25, 0.5), temperature (290 °C, 330 °C, 370 °C), and reaction time (0 min, 30 min, 60 min). The literature reports positive synergistic interactions in hydrothermal co-liquefaction of biomass and plastics; however, in this work, only negative synergistic interactions could be observed. A reason could be the high thermal stability of produced fatty acids that give little room for interactions with plastics. At the same time, mass might transfer to other product phases. Full article