Search Results (2,790)

The increasing amount of multilayer packaging waste poses significant environmental challenges and calls for sustainable valorization solutions. This study aimed to investigate the acoustic properties of composite materials produced by hot-pressing multilayer waste without the addition of binders or other substances. The waste was carefully cleaned and shredded into square or strip-like geometries, and the composite material plates were compressed at different temperatures (120 °C, 125 °C, 130 °C, 135 °C, and 140 °C) under a constant pressure of 5 MPa. The sound absorption coefficients were evaluated for representative samples, with results analyzed as a function of constituent geometry and processing temperature. Experimental results indicate that the pressing temperature critically affects the internal structure of the material, while waste shape exhibits a frequency-dependent influence on the absorption coefficient. The resulting composite materials display low porosity, which limits internal sound absorption and promotes sound wave reflection, indicating that these materials are more suitable for sound insulation rather than acoustic absorption. These results highlight the potential of multilayer packaging waste-based composites as a sustainable solution for noise control applications and highlight the importance of processing parameters in tailoring their acoustic performance. Full article

This study shows an optimal model to estimate the minimum area in contact with the soil for an EIF (elliptical isolated footing), assuming that the partially compressed area, that is, part of the surface below the base in contact with the ground, is compressed, and the other part is not compressed (the pressure of the ground is linear). There are works that show the minimum area for an elliptical isolated footing, but the surface below the base in contact with the ground is fully compressed. The model is developed by integration to determine the equations of the axial load and the two moments (X and Y axes) for the two cases. Two numerical studies are presented: Study 1 considers that the axial load varies, and the moments are equal and remain constant; Study 2 considers that the axial load varies, and the moments are different and remain constant. Two comparisons are also made with the model proposed by other authors (fully compressed area) and the new model (partially compressed area): In the first study, it is assumed that axial load and moment about the X-axis remain constant and moment about the Y-axis is variable; in the second study, it is assumed that the two moments remain constant and the axial load is variable. The results show that significant savings of up to 59.30% can be achieved in the first study and up to 65.67% in the second study in the area of contact with the ground. Another comparison is made between rectangular isolated footings and EIFs; the results indicate that savings of up to 63.18% can be achieved using EIFs. Therefore, this article will be of great help to specialists in foundation engineering. Full article

Background: Health care work contributes significantly to greenhouse gas emissions. Primary health care is community-based and focused on wellness and disease prevention. Within primary health care, pharmacists are most frequently the stewards of medicines, supplies, and other tangible products that contribute to carbon footprints. Pharmacists are in a unique position to help adapt to and mitigate climate change-related issues. Objective: To examine pharmacists’ perspectives on climate adaptation and mitigation strategies in primary health care delivery in interprofessional settings. Methods: Semi-structured qualitative interviews with primary care pharmacists were undertaken. Constant-comparative data analysis was used to code and categorize findings. The COREQ system was applied to ensure rigor and quality of research. Results: A total of 21 primary care pharmacists participated in this research. Several core themes emerged as follows: (a) universal agreement that climate change is real and primary health care needs to evolve rapidly to address it; (b) recognition that primary health care is time-pressured and resource constrained so successful solutions need to be pragmatic and work within realities of practice; (c) identification of actionable priorities with high potential for mitigation impact; and (d) mobilization of a coalition to develop system-wide initiatives that could be implemented in primary health care. Conclusions: Collaborative approaches and those that focus on the implementation of regulatory requirements were identified as being most productive in this setting. Full article

In this paper, we consider the inevitable large fluctuations of pressure in typical molecular dynamics (MD) simulations of ligand–protein binding problems. In simulations under the constant pressure of one bar, the pressure artifactually fluctuates over the range of $\pm 100$ bars or more. This artifact can cause gross inaccuracy in the apparent binding affinity computed as the ratio of the probability for the ligand to be bound inside the protein and the probability for the ligand to be outside the protein. Based on statistical thermodynamics, we derive a correction factor for the ligand–protein binding affinity to compensate for the artifactual pressure fluctuations. The correction factor depends on the change in the system volume between the bound and the unbound states of the ligand. We conducted four sets of MD simulations for glycerol affinities with four aquaglyceroporins: AQP10, AQP3, AQP7, and GlpF. Without the correction factor, the apparent affinity of glycerol with each of these four aquaglyceroporins is computed directly from the simulations to be very low (~1/M). With the correction factor applied, glycerol’s affinity is computed to be 1/mM to 1/µM. In conclusion, glycerol has high affinity for its native facilitator aquaglyceroporins, which is in contrast to the current literature not correcting the artifactual consequences of the large pressure fluctuations in typical in silico experiments. Full article

Copepods are key components of marine food webs, linking primary producers such as microalgae to higher trophic levels, including many fish species. This study investigates long-term changes in the composition, density, and biomass of copepod communities along the Romanian coast of the Black Sea over six decades (1956–2015), based on historical records and recent monitoring from 18 sampling stations. Mean copepod density declined markedly over the study period, particularly during the cold season, decreasing from values exceeding 1000 ind/m³ in the 1960s to <300 ind/m³ after 2000, while biomass showed weaker but comparable long-term fluctuations. Seasonal variability was pronounced, with significantly higher densities and biomass during the warm season. Generalised Additive Models (GAMs) explained up to 40–55% of the variance in copepod density and biomass, depending on the season. During the warm season, phosphate exerted a positive effect on copepod abundance, consistent with bottom-up control via phytoplankton productivity, whereas during the cold season, temperature showed a positive effect and salinity a negative effect, indicating stronger physical control of copepod persistence. Species composition shifted over time, with a reduction in constant species and an increase in rare or accidental taxa in later decades. These results indicate that climate variability and anthropogenic pressures have reshaped copepod communities, with potential consequences for food-web efficiency and ecosystem resilience in the Black Sea. Full article

High regeneration energy demand remains a critical barrier to the large-scale deployment of ethanolamine-based (MEA-based) CO₂ capture. This study adopts an Al₂O₃ ceramic-membrane heat exchanger (CMHE) to recover both sensible and latent heat from the stripped gas. Experiments confirm that heat and mass transfer within the CMHE follow a coupled mechanism in which capillary condensation governs trans-membrane water transport, while heat conduction through the ceramic membrane dominates heat transfer, which accounts for more than 80%. Guided by this mechanism, systematic structural optimization was conducted. Alumina was identified as the optimal heat exchanger material due to its combined porosity, thermal conductivity, and corrosion resistance. Among the tested pore sizes, CMHE-4 produces the strongest capillary-condensation enhancement, yielding a heat recovery flux (q value) of up to 38.8 MJ/(m² h), which is 4.3% and 304% higher than those of the stainless steel heat exchanger and plastic heat exchanger, respectively. In addition, Length-dependent analyses reveal an inherent trade-off: shorter modules achieved higher q (e.g., 14–42% greater for 200-mm vs. 300-mm CMHE-4), whereas longer modules provide greater total recovered heat (Q). Scale-up experiments demonstrated pronounced non-linear performance amplification, with a 4 times area increase boosting q by only 1.26 times under constant pressure. The techno-economic assessment indicates a simple payback period of ~2.5 months and a significant reduction in net capture cost. Overall, this work establishes key design parameters, validates the governing transport mechanism, and provides a practical, economically grounded framework for implementing high-efficiency CMHEs in MEA-based CO₂ capture. Full article

This paper investigates pseudo-symmetric space–times within two interrelated frameworks: vacuum $f\left(R\right)$-gravity and Gray’s seven canonical decomposition subspaces. First, it is established that any conformally flat pseudo-symmetric space–time satisfying the vacuum field equations of $f\left(R\right)$-gravity necessarily corresponds to a perfect fluid. Subsequently, a detailed analysis of Gray’s subspaces reveals the following structural results: In the trivial and $\mathsf{𝒜}$ subspaces, pseudo-symmetric space–times are Ricci-simple and Weyl-harmonic, and thus are necessarily generalized Robertson–Walker space–times. In the $\mathcal{B}$ and $\mathsf{𝒜}\oplus \mathcal{B}$ subspaces, the associated time-like vector field ${\xi }^l$ is shown to be an eigenvector of the Ricci tensor with the eigenvalue $-R/2$. Furthermore, for a perfect fluid pseudo-symmetric space–time obeying $f\left(R\right)$-gravity and belonging to the trivial, $\mathsf{𝒜}$, $\mathcal{B}$, or $\mathsf{𝒜}\oplus \mathcal{B}$ subspaces, the isotropic pressure p and energy density $\sigma$ are proven to be constants. Additionally, it is demonstrated that Gray’s $\mathcal{I}$ subspace reduces to the $\mathcal{B}$ subspace in the pseudo-symmetric setting. Finally, under specific geometric conditions, pseudo-symmetric space–times in the $\mathcal{I}\oplus \mathsf{𝒜}$ and $\mathcal{I}\oplus \mathcal{B}$ subspaces are also shown to admit perfect fluid representations. These results collectively clarify the geometric and physical constraints imposed by pseudo-symmetry within $f\left(R\right)$-gravity and Gray’s classification scheme. Full article

To reveal the physical evolution of methanol spray under different environmental conditions and injection strategies, this study focuses on the atomization and evaporation behavior of low-pressure methanol spray. The coupled effects of temperature, pressure, and injection parameters are systematically investigated based on constant-volume combustion chamber experiments and three-dimensional CFD simulations. The formation, evolution, and interaction mechanisms of the liquid column core and cooling core are revealed. The results indicate that temperature is the dominant factor influencing methanol spray atomization. When the temperature increases from 255 K to 333 K, the spray penetration distance increases by approximately 70%, accompanied by a pronounced shortening of the liquid-core length and enhanced evaporation and air entrainment. Under low-temperature conditions, a stable liquid-core structure and a strong cooling core are formed, characterized by a high-density, long-axis morphology and an extensive low-temperature region, which suppress fuel–air mixing and ignition. Increasing the ambient pressure improves spray–air mixing but reduces penetration; at 255 K, increasing the ambient pressure from 0.05 MPa to 0.2 MPa increases the spray cone angle by approximately 10% while reducing the penetration distance by about 50%. Furthermore, optimizing the injection pressure or shortening the injection pulse width effectively enhances atomization performance: increasing the injection pressure from 0.4 MPa to 0.6 MPa and reducing the pulse width from 5 ms to 2 ms increases the penetration distance by approximately 30% and reduces the mean droplet diameter by about 20%. Full article

Background: Semi-occluded vocal tract exercises (SOVTE) improve vocal quality and capacity. Water resistance therapy (WRT), a specific form of SOVTE with a tube submerged under water, generates increased and oscillating oral pressure through bubble formation during phonation, thereby influencing transglottal pressure and vocal fold dynamics. While the physiological effects of WRT using tube-based systems have been extensively studied, the influence of vowel-specific vocal tract configurations during WRT remains unclarified. This study examined how different vowel qualities during WRT affect vocal fold oscillation using the DoctorVox^® mask, which allows near-natural mouth opening and vowel articulation. Methods: Ten vocally healthy, untrained adults (25–50 years) performed a continuous vowel glide (/i/–/a/–/u/-/i/) at constant fundamental frequency and habitual loudness during WRT using the DoctorVox^® mask, with the tube submerged 2 cm in water. Simultaneous recordings included transnasal high-speed videoendoscopy (20,000 fps), electroglottography (EGG), acoustic signals and intra-tube oral pressure measurements. Glottal area waveforms (GAW) were derived to calculate the open quotient (OQ_GAW) and closing quotient (ClQ_GAW). Analyses were conducted separately for intra-tube pressure maxima, minima and intermediate phases within the bubble cycle during WRT. Statistical analysis used Wilcoxon signed-rank tests with Bonferroni correction. Results: In the baseline condition without WRT, significant vowel-related differences were found: /u/ showed a higher open quotient than /i/ and /a/ (p < 0.05) and a higher closing quotient than /a/ (p < 0.05). During WRT, these vowel-specific differences were no longer statistically significant. A non-significant trend toward reduced OQ_GAW during WRT was observed, most notably for /u/, while differences between pressure phases within the bubble cycle were minimal. Conclusions: WRT using the DoctorVox^® mask reduces vowel-specific differences in vocal fold vibration patterns, suggesting that for voice therapy, vowel quality modifications during WRT have little impact on vocal outcomes. Full article

This study provides a comparison between the impact of two gas fuels, compressed natural gas (CNG) and hydrogen (H₂), on the exhaust emissions of a single-cylinder diesel engine operating in dual-fuel mode. The analysis is conducted with a constant and maximum achieved gas-to-total-fuel ratio (K = 20% and K = max) under varying load conditions, specifically at an engine speed of 2000 min⁻¹ and brake mean effective pressures ranging from 0.2 to 0.43 MPa. The results reveal that H₂ significantly improves the engine’s emissions profile compared to CNG. When H₂ is used as the secondary fuel, reductions in soot, carbon monoxide (CO), carbon dioxide (CO₂), and unburned hydrocarbons (CHs) are more pronounced. However, under certain load conditions, nitrogen oxide (NO_x) emissions are higher with H₂ than with CNG and can even surpass those observed during diesel-only operation. These findings suggest that while H₂ demonstrates superior overall emissions performance, its impact on NO_x emissions under specific conditions requires further optimization to maximize environmental benefits. Full article

Pellets produced from raw or torrefied shredded logging residues have been investigated in the study. The research material came from pine and spruce stands in Poland, Slovakia, Czechia and Hungary. Torrefaction temperatures (T_t) of 250, 300, and 400 °C were applied. Before pressure agglomeration, 3% wheat flour was added to the torrefaction material as a binding agent. Pellets with a diameter of 8 mm were produced at constant humidity, compaction pressure (P) of 140 or 180 MPa and agglomeration temperature (T_a) of 100, 120 or 140 °C. The produced pellets were assessed for their physicomechanical parameters (density, radial compressive strength, compression ratio, modulus of elasticity), chemical parameters (extractive compounds, cellulose, lignin) and energy parameters (ash content, elemental composition, calorific value). The results were subjected to basic statistical analysis and multi-way ANOVA. The produced pellets varied in physical, mechanical, chemical and energy properties. A significant effect of torrefaction temperature, agglomeration temperature and compaction pressure on the results was observed. In terms of physicomechanical parameters, the best pellets were produced from the raw material, while in terms of energy parameters, those produced from the torrefied material were superior. Pellets of satisfactory quality produced from torrefied logging residues could be obtained at T_t = 250 °C, T_a = 120 °C and P = 180 MPa. Pellets with specific density of approximately 1.1 g·cm⁻³, radial compressive strength of 3–3.5 MPa, modulus of elasticity of 60–80 MPa and calorific value of 20.3–23.8 MJ·kg⁻¹ were produced in the process. Full article

Brake squeal is an undesirable high-frequency noise caused by vibrations induced by friction in disc brake systems. The noise is strongly affected by temperature, as this influences the material properties of the friction pair and the dynamic behaviour of the brake components. This study investigates the effect of temperature changes on the squeal characteristics of a disc brake system under different operating conditions. Experiments are carried out using a laboratory-scale test setup comprising a rotating disc, pneumatically actuated callipers, and precise measurement equipment. A series of test combinations is performed by systematically varying three parameters: disc surface temperature (40, 55, 70, 85, 100 °C), brake pressure (4.0 bar), and disc rotational speed (50, 100, 150, 200 rpm). Acceleration data are acquired using an accelerometer mounted directly on the calliper, while sound pressure data are measured with a fixed-position microphone located 0.5 m from the disc surface. The collected data are analyzed in the time and frequency domain to identify squeal events and their dominant frequencies. The effect of temperature on brake squeal noise and vibration varies with operating conditions, showing different patterns at low and high disc speed at constant brake pressure. This highlights the importance of considering both thermal and mechanical factors together when addressing brake squeal. Full article

In the pursuit of cleaner and more efficient internal combustion engines, dual-fuel strategies combining diesel and hydrogen are gaining increasing attention. This study employs detailed computational fluid dynamics (CFD) simulations to investigate the behaviour of pilot diesel injections in dual-fuel diesel–hydrogen engines. The study aims to characterize spray formation, ignition delay and early combustion phenomena under various energy input levels. Two combustion models were evaluated to determine their performance under these specific conditions: Tabulated Well Mixed (TWM) and Representative Interactive Flamelet (RIF). After an initial numerical validation using dual-fuel constant-volume vessel experiments, the models are further validated using in-cylinder pressure measurements and high-speed natural combustion luminosity imaging acquired from a large-bore optical engine. Particular attention was given to ignition location due to its influence on subsequent hydrogen ignition. Results show that both combustion models reproduce the experimental behavior reasonably well at high energy input levels (EILs). At low EILs, the RIF model better captures the ignition delay; however, due to its single-flamelet formulation, it predicts an abrupt ignition of all available premixed charge in the computational domain once ignition conditions are reached in the mixture fraction space. Full article

We propose a unified theoretical framework grounded in a Primordial Quantum Field (PQF)—a continuous, non-local informational substrate that precedes space-time and matter. The PQF is represented by a wave functional evolving in an abstract configuration space, where physical properties emerge through the self-organization of complexity. We introduce a novel physical quantity—complexity entropy Sc[ϕ]—which quantifies the structural organization of the PQF. Unlike traditional entropy measures (Shannon, von Neumann, Kolmogorov), Sc[ϕ] captures non-trivial coherence and functional correlations. We demonstrate how complexity gradients induce an emergent geometry, from which spacetime curvature, physical constants, and the arrow of time arise. The model predicts measurable phenomena such as entanglement waves and reinterprets dark energy as informational coherence pressure, suggesting empirical pathways for testing via highly correlated quantum systems. Full article

In this study, to reveal the changes in explosion pressure and flame propagation characteristic, a 12 L cylindrical explosion device was used to conduct experiments on the explosions of two-phase mixtures of paper powder and volatile organic compounds (VOCs) at varying concentrations. The findings indicate that, at a constant paper powder concentration, increasing the VOCs concentration initially causes minor fluctuations in the maximum explosion pressure (P_max), followed by an increase. At a constant VOCs concentration, as the paper powder concentration rises, the P_max also increases, while the time to reach peak explosion pressure initially decreases before increasing. Additionally, under the two-phase concentration range produced in the production process, higher concentrations of paper powder and VOCs significantly enhance flame brightness, combustion intensity, heat release rate, and flame duration. These insights provide data support for determining the alarm limit values of VOCs concentration detection, provide a scientific basis for evaluating and predicting explosion risks associated with paper powder and VOCs, offering significant practical implications for fire and explosion prevention in the printing industry. Full article