Search Results (103)

Phase equilibrium calculations are crucial in chemical engineering design and optimization processes. The PC-SAFT equation of state (EoS) can precisely calculate phase equilibrium, but is relatively complex and computationally intensive. Surrogate models are mathematically simple models that map or regress the input–output relationships of more complex, computationally demanding models. This work employs XGBoost and a hybrid XGBoost-artificial neural networks (XGBoost-ANN) model as surrogate models to replace PC-SAFT EoS calculations for the vapor–liquid equilibrium (VLE) of binary associating systems. This work investigates the VLE of five binary associating systems using data generated by the PC-SAFT EoS. The surrogate models take temperature, pressure, liquid phase mole fractions, and the PC-SAFT parameters for binary associating systems as inputs, and predict the vapor phase mole fractions. Both surrogate models significantly reduce the computational time for calculating VLE data compared to the PC-SAFT EoS, while achieving good prediction results. Full article

The shadow economy weakens fiscal sustainability, hampers the financing of public goods, and impedes the achievement of sustainable development goals. The informal sector remains a persistent challenge for policymakers, as it distorts competition, reduces transparency, and undermines the effectiveness of economic and fiscal policies. The aim of this article is to identify the key factors determining the size of the shadow economy in European Union countries and to provide policy-relevant insights. The analysis covers data on the share of the informal economy in GDP and macroeconomic variables such as GDP per capita, consumer price index, average wages, household consumption, government expenditure, and unemployment, as well as indicators of digital development in society and the economy (DESI, IDT), the share of cashless transactions in GDP, and information on the implementation of digital tax administration tools and restrictions on cash payments. Five hypotheses (H1–H5) are formulated concerning the effects of income growth, labour market conditions, digitalisation, cashless payments, and tax administration tools on the shadow economy. The research question addresses which factors—macroeconomic conditions, economic and social digitalisation, payment structures, and fiscal innovations in tax administration—play the most significant role in determining the size of the shadow economy in EU countries and whether these mechanisms have broader implications for fiscal sustainability and sustainable development. The empirical strategy is based on multilevel models with countries as clusters, complemented by correlation and comparative analyses. The results indicate that the most significant factor in limiting the size of the shadow economy is the level of GDP per capita and its growth, whereas the impact of card payments appears to be superficial, reflecting overall increases in wealth. Higher wages, household consumption, and digital development as measured by the DESI also play an important role. The implementation of digital solutions in tax administration, such as SAF-T or e-PIT/pre-filled forms, along with restrictions on cash transactions, can serve as complementary measures. The findings suggest that sustainable strategies to reduce the shadow economy should combine long-term economic growth with digitalisation and improved tax administration, which may additionally foster the harmonisation of economic systems and support sustainable development. Full article

Traditional techniques for detecting internal defects in concrete are limited by the weak directivity of ultrasonic waves, significant signal attenuation, and low imaging contrast. This paper presents an improved synthetic aperture focusing technique (SAFT) enhanced by the Delay Multiply and Sum (DMAS) algorithm to address these limitations and improve both the resolution and signal-to-noise ratio. The proposed method sequentially transmits and receives ultrasonic waves through an array of transducers, and applies DMAS-based nonlinear beam-forming to enhance image sharpness and contrast. Its effectiveness was validated through finite element simulations and experimental tests using three precast concrete specimens with artificial defects (specimen size: 240 mm × 300 mm × 100 mm). Compared with the conventional SAFT, the proposed method improves image contrast by approximately 40%, with clearer defect boundaries and a vertical positioning error of less than ±5 mm. This demonstrates the method’s promising potential for practical applications in internal defect visualization of concrete structures. Full article

The presence of mosquitoes in a certain area is sufficient evidence of the transmission of diseases, in addition to the inconvenience and harassment they cause to the population. In order for mosquito control to be successful, there must be sufficient reports and information about the extent of the distribution and spread of the mosquito in this area. This study was conducted seasonally to calculate the distribution and abundance of mosquitoes and to initially detect hepatitis C virus in the most abundant species collected in some localities: Kafr Saqr (Hanot, El-Kodah, Abo Shokok, El-Hagarsa); Abo Kebeer (Manshat Radwan, Bane Aiat, Al-Rahmania, Horbat); Diarb Negm (Safor, El-Asaied, Karmot Sahbara, Saft Zreka); and El-Zakazik (Om El-Zein, Bany Amer, Al-Zankalon, Shanbrt El-Mimona) along Sharkia Governorate. According to the results, 12 mosquito species belonging to two genera were recorded in four stations (16 sites). The species Culex pipiens was found to be the most abundant across the majority of locations. It is reaching its peak in Al-Zankalon with a maximum count of 139 ± 7.61 individuals. C. antennatus exhibited a significant level of abundance (p < 0.001), especially in Al-Rahmania (82.5 ± 4.3). Species such as C. perexiguus and An. pharoensis were found in moderate-to-low numbers. The prevailing species is C. pipiens in all locations and seasons, especially during the summer. Other species like C. antennatus and An. pharoensis are also important, although their significance is somewhat less pronounced. Clusters of sites with similar features indicate that specific locations or species exhibit consistent patterns of activity or abundance throughout several seasons. These clusters represent groups of locations that share similar characteristics, as determined by the principal components. The findings of detecting hepatitis C virus in C. pipiens (the most abundant species) collected samples showed negative results for the presence of HCV during the summer season in Sharkia Governorate. Full article

Knowledge of the solubility of metal precursors in supercritical (sc) CO₂ is a key factor for determining the best operation conditions for the synthesis of supported metallic nanoparticles. In this paper, new experimental solubility data of Cu(acac)₂, Pd(acac)₂, and Pt(acac)₂ in scCO₂ for temperatures from 313 to 353 K and pressures from 10 to 40 MPa are presented and compared with the literature data and correlated with semi-empirical density-based models (Chrastil, extended Kumar and Johnston, extended Bartle, and the original and modified Méndez–Santiago–Teja). In addition, literature data for the solubility of Cu(tmhd)₂, Pd(tmhd)₂, and Pt(cod)me₂ in scCO₂ were also correlated with the above-mentioned models. The best result, i.e., the best agreement between the experimental and calculated solubility datasets, was observed for the Chrastil model. Applying the Chrastil and extended Bartle models, the dissolution, sublimation, and solvation enthalpies were estimated. Furthermore, these correlation results were compared with the results from Ushiki et al., who correlated the solubilities of metal acetylacetonates in scCO₂ from the literature using the PC-SAFT equation of state. This comparison showed that the original Méndez–Santiago–Teja model enabled a better description of the experimental data by a factor of three. Full article

Huntington’s disease is a progressive, untreatable neurodegenerative disorder caused by a mutation in the Huntingtin gene. Next to neurodegeneration, altered immune activation is involved in disease progression. Since central nervous system inflammation and dysfunction of immune cells are recognized as driving characteristics, immunomodulation might represent an additional therapeutic strategy. Short-chain fatty acids were known to have immunomodulatory effects in neuroinflammatory diseases, such as multiple sclerosis. In this study, R6/2 mice were treated daily with 150 mM propionate. Survival range, body weight, and motor abilities were monitored. In striatal and cortical samples, neuronal survival was analyzed by immunofluorescence staining of NeuN-positive cells and expression levels of BDNF mRNA by real-time polymerase chain reaction. As inflammatory marker TNFα mRNA and IL-6 mRNA were quantified by rtPCR, iNOS-expressing cells were counted in immunologically stained brain slides. Microglial activation was evaluated by immunofluorescent staining of IBA1-positive cells and total IBA1 protein by Western Blot, in addition, SPI1 mRNA expression was quantified by rtPCR. Except for clasping behavior, propionate treatment did neither improve the clinical course nor mediated neuronal protection in R6/2 mice. Yet there was a mild anti-inflammatory effect in the CNS, with (i) reduction in SPI1-mRNA levels, (ii) reduced iNOS positive cells in the motor cortex, and (iii) normalized TNFα-mRNA in the motor cortex of propionate-treated R6/2 mice. Thus, Short-chain fatty acids, as an environmental factor in the diet, may slightly alleviate symptoms by down-regulating inflammatory factors in the central nervous system. However, they cannot prevent clinical disease progression or neuronal loss. Full article

Ultrasonic TOFD imaging, as an important non-destructive testing method, has a wide range of applications in pipeline girth weld inspection and testing. Due to the limited bandwidth of ultrasonic transducers, near-surface defects in the weld are masked and cannot be recognized, resulting in poor longitudinal resolution. Affected by the inherent diffraction effect of scattered acoustic waves, defect images have noticeable trailing, resulting in poor transverse resolution of TOFD imaging and making quantitative defect detection difficult. In this paper, based on the assumption of the sparseness of ultrasonic defect distribution, by constructing a convolutional model of the ultrasonic TOFD signal, the Orthogonal Matching Pursuit (OMP) sparse deconvolution algorithm is utilized to enhance the longitudinal resolution. Based on the synthetic aperture acoustic imaging model, in the wavenumber domain, backpropagation inference is implemented through phase transfer technology to eliminate the influence of diffraction effects and enhance transverse resolution. On this basis, the time-domain sparse deconvolution and frequency-domain synthetic aperture focusing methods mentioned above are combined to enhance the resolution of ultrasonic TOFD imaging. The simulation and experimental results indicate that this technique can outline the shape of defects with fine detail and improve image resolution by about 35%. Full article

Advanced nanocomposite membranes incorporate nanomaterials within a polymer matrix to augment the mechanical strength of the resultant product. Characterizing these membranes through molecular modeling necessitates specialized approaches to accurately capture the length scales, time scales, and structural complexities inherent in polymers. To address these requirements, an efficient simulation protocol is proposed, utilizing coarse-grained (CG) molecular dynamics simulations to examine the mechanical properties of polyethylene/single-walled carbon nanotube (PE/SWCNT) composites. This methodology integrates CG potentials derived from the statistical associating fluid theory (SAFT-$\gamma$ Mie) equation of state and a modified Tersoff potential as a model for SWCNTs. A qualitative correspondence with benchmark classical all-atom models, as well as available experimental data, is observed, alongside enhanced computational efficiency. Employing this CG model, the focus is directed at exploring the mechanical properties of PE/SWCNT composites under both tensile and compressive loading conditions. The investigation covered the influence of SWCNT size, dispersion, and weight fraction. The findings indicate that although SWCNTs enhance the mechanical strength of PE, the extent of enhancement marginally depends on the dispersion, filler size, and weight fraction. Fracture strengths may be elevated by 20% with a minor incorporation of SWCNTs. Under compression, the incorporation of SWCNTs into the composites results in a transformation from brittle to tough materials. These insights contribute to the optimization of PE/SWCNT composites, emphasizing the importance of considering multiple factors to fine-tune the desired mechanical performance. Full article

The study of solid–liquid equilibria offers critical insights into the molecular interactions between constituents in binary mixtures. Predicting these equilibria often requires comprehensive thermodynamic models, yet simplified approaches can provide valuable perspectives. In this work, we explore the application of the Bragg–Williams model to solid–liquid equilibria in binary mixtures leading to the formation of eutectic solvents. This model relies on a single parameter—the molar energy change upon mixing compounds—and demonstrates noteworthy features: the parameter can be estimated from a few (in principle, from a single) experimental melting points, and it correlates strongly with interaction energy parameters from more complex models, such as the PC-SAFT molecular-based equation of state. By using the Bragg–Williams model, we provide a straightforward and informative framework for characterizing solid–liquid equilibria, enabling insights into molecular interactions while requiring few data points as input. Despite its simplicity, the model effectively captures the essence of binary mixture energetics, positioning it as a practical tool for advancing the understanding of phase behavior in eutectic solvent systems. Full article

Background: Modeling tools should be tested against real-world outcomes to confirm their predictive ability compared to random chance. Insights is an analytical tool within the biomathematical modeling software SAFTE-FAST that identifies work patterns that consistently result in elevated fatigue risk. This study investigated the ability of Insights to correctly identify duties with an associated fatigue report using previously collected flight schedule and report data. Methods: Planned and completed flight roster schedules were analyzed using SAFTE-FAST Insights after the rosters had been flown. Fatigue reports were independently linked to planned and completed schedules at the duty level. Odds ratio (OR) analysis investigated the ability of Insights to predict which duties would be linked to a fatigue report. Differences in duties were compared using a one-way analysis of variance (ANOVA) and a two-sample t-test. Results: There were 157 fatigue reports out of 78,061 planned duties and 235 fatigue reports out of 82,612 completed duties. Insights had 3.04 odds of correctly identifying fatigue reports in planned duties but 0.41 odds for completed duties. Discussion: Insights showed good odds of correctly identifying a fatigue report duty using planned schedules but poor odds of identifying a fatigue report duty from completed schedules. Completed duties started later in the day and were shorter in duration than planned duties. Day-of-operations schedule changes may have reduced the fatigue risk in response to the fatigue reports. Full article

In this work, new self-adhesive materials were obtained based on cross-linked silicone self-adhesives obtained by modifying the composition with the addition of a silicon filler, olivine. Silicone pressure-sensitive resin DOWSIL 7358 was used as a basis and modified with various amounts of olivine. New materials (self-adhesive tape samples) were characterized in terms of peel adhesion, tack, cohesion at room and elevated temperatures, SAFT test (shear adhesion failure temperature), pot life (storage stability), and shrinkage (dimensional stability). During the tests, an increase in thermal resistance (>225 °C) and a drastic reduction in shrinkage values (below 0.5%) were noted for all modified samples tested. All tests were performed in compliance with international standards, e.g., FINAT FTM 1, FINAT FTM 8, FINAT FTM 9, FINAT FTM 14, and GTF 6001. This allows us to conclude that the new material has significant application potential due to the good performance results. The results of adhesion and tack were in ranges accepted in the PSA industry, cohesion was kept at an unchanged level (above 72 h), and a great increase in the thermal resistance was observed (from 147 °C for pure resin to high above 225 °C for even the smallest additions of the olivine powder. Moreover, the shrinkage of prepared adhesive films was reduced significantly. In the available literature, there are no references to the modification of adhesives using powdered silicon minerals of natural origin, which is a novelty due to their higher bulk density compared to commercial powdered silicon fillers. Full article

Background: During the dissolution of amorphous solid dispersion (ASD) formulations, the drug load (DL) often impacts the release mechanism and the occurrence of loss of release (LoR). The ASD/water interfacial gel layer and its specific phase behavior in connection with DL strongly dictate the release mechanism and LoR of ASDs, as reported in the literature. Thermodynamically driven liquid-liquid phase separation (LLPS) and/or drug crystallization at the interface are the key phase transformations that drive LoR. Methods: In this study, a combination of Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) thermodynamic modeling and in silico molecular simulation was applied to investigate the release mechanism and the occurrence LoR of an ASD formulation consisting of ritonavir as the active pharmaceutical ingredient (API) and the polymer, polyvinylpyrrolidone-co-vinyl acetate (PVPVA64). A thermodynamically modeled ternary phase diagram of ritonavir (PVPVA64) and water was applied to predict DL-dependent LLPS in the ASD/water interfacial gel layer. Microscopic Erosion Time Testing (METT) was used to experimentally validate the phase diagram predictions. Additionally, in silico molecular simulation was applied to provide further insights into the phase separation, the release mechanism, and aggregation behavior on a molecular level. Results: Thermodynamic modeling, molecular simulation, and experimental results were consistent and complementary, providing evidence that ASD/water interactions and phase separation are essential factors driving the dissolution behavior and LoR at 40 wt% DL of the investigated ritonavir/PVPVA64 ASD system, consistent with previous studies. Conclusions: This study provides insights into the potential of blending thermodynamic modeling, molecular simulation, and experimental research to comprehensively understand ASD formulations. Such a combined approach can be leveraged as a computational framework to gain insights into the ASD dissolution mechanism, thereby facilitating in silico screening, designing, and optimization of formulations with the benefit of significantly reducing the number of experimental tests. Full article

To optimally preserve and manage our civil structures, we need to have accurate information about their (1) geometry and dimensions, (2) boundary conditions, (3) material properties, and (4) structural conditions. The objective of this article is to show how imaging and image fusion using non-destructive testing (NDT) measurements can support structural engineers in performing accurate structural evaluations. The proposed methodology involves imaging using synthetic aperture focusing technique (SAFT)-based image reconstruction from ground penetrating radar (GPR) as well as ultrasonic echo array (UEA) measurements taken on multiple surfaces of a structural member. The created images can be combined using image fusion to produce a digital cross-section of the member. The feasibility of this approach is demonstrated using a case study of a prestressed concrete bridge that required a bridge load rating (BLR) but where no as-built plans were available. Imaging and image fusion enabled the creation of a detailed cross-section, allowing for confirmation of the number and location of prestressing strands and the location and size of internal voids. This information allowed the structural engineer of record (SER) to perform a traditional bridge load rating (BLR), ultimately avoiding load restrictions being imposed on the bridge. The proposed methodology not only provides useful information for structural evaluations, but also represents a basis upon which the digitalization of our infrastructure can be achieved. Full article

Industrial buildings have numerous kinds of energy-losing equipment, such as engines, ovens, boilers and heat exchangers. Energy losses are related to inefficient energy use and lousy work conditions for the people inside the buildings. This work is devoted to the recovery of lost energy from industrial buildings. Firstly, the residual energy of the building is extracted to be used to warm water. Consequently, the work conditions of the people inside industrial buildings can be improved by maintaining the adequate temperature. The recovery of the energy is performed by a multipurpose heat pump system (HP system). The working fluid used in the HP system is R134a, which is a traditional and cheap working fluid. The thermophysical properties of R134a are obtained through the PC-SAFT equation of state. This work presents a performance mapping based on the intercepted areas framework to evaluate which working conditions are the optimal operating variables. The latter depends on several key parameters, such as compressor work, heat delivery, heat absorbed and exergetic efficiency. The results show that the optimal work conditions are found at different condenser and evaporator temperatures, and these may be limited by what the designer considers a sound performance of the heat pump system. Full article

This work compares photoacoustic images of a tooth by analyzing the signals generated with wavelengths 532 and 355 nm. This comparison addresses the differences in the optical properties of dental tissue for these wavelengths that affect the resulting photoacoustic images. A pulsed Nd:YAG laser was used to illuminate a complete extracted tooth sample, and 2D photoacoustic images (PAIs) were reconstructed using the single-sensor scanning synthetic aperture focusing technique (SSC-SAFT), which is a suitable method for our experimental system with forward detection mode. Signal comparison was conducted using sinogram, signal-to-noise ratio (SNR), root mean square (RMS), arrival time, maximum amplitude, and fast Fourier transform (FFT). PAI comparison utilized intensity profile, edge correlation, and image composition tools. The signal analysis revealed that at 532 nm, the signals exhibited longer decay time and a wider distribution of vibration frequencies due to higher laser pulse energy and greater optical penetration depth. Conversely, at 355 nm, the signals had shorter decay times and a lower frequency distribution, which was attributed to lower energy but improved optical absorption, resulting in reconstructed images with better sharpness and contour definition. This study contributes to the advancement of photoacoustic imaging technology in dentistry by providing insights that could optimize signal generation and image reconstruction for dental tissue. Full article