bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Detection of SARS-CoV-2 Viral Particles in Exhaled Breath Condensate via Engineered Face Masks
Authors: Dörfler Hannes , Daniels John , Wadekar Shekhar , Pagneux Quentin , Ladage Dennis , Greiner Georg , Assadian Ojan , Boukherroub Rabah , Szunerits Sabine
Published: November 2024

In this study, we present a novel face mask engineered for the collection of exhaled breath condensate (EBC) and its application and performance in a clinical study of COVID-19 infection status assessment versus the gold standard polymerase chain reaction (PCR) nasopharyngeal swab testing. EBC was collected within a clinical trial of COVID-19-infected and non-infected patients and analyzed by reverse transcription quantitative (RT-q) PCR, with the results being compared with nasopharyngeal sampling of the same patient. The cycle threshold (Ct) values of the nasopharyngeal samples were generally lower than those of EBC, with viral loads in EBC ranging from 1.2 × 104 to 5 × 108 viral particles mL−1 with 5 min of breathing. From the 60 clinical patients’ samples collected, 30 showed a confirmed SARS-CoV-2 infection. Of these 30 individuals, 22 (73%) had Ct values < 40 (representing the threshold for SARS-CoV-2 infectivity) using both amplification of ORF1a/b and the E-gene. The 30 EBC samples from non-infected participants were all identified as negative, indicating a 100% specificity. These first results encourage the use of the face mask as a noninvasive sampling method for patients with lung-related diseases, especially with a view to equipping the face mask with miniaturized sensing devices, representing a true point-of-care solution in the future.
Can Open Government Data Improve City Green Land-Use Efficiency? Evidence from China
Authors: Peng Xiang , Xiao Deheng
Published: November 2024

This study adopted the double difference method to study the effect of open government data (OGD) on city green land-use efficiency (CGLUE). It was found that opening government data had a significant promotional effect on CGLUE, and a number of robustness tests were the foundation for this finding. A mechanism analysis demonstrated that two key avenues via which government data openness can promote CGLUE are raising public awareness of environmental issues and strengthening urban green innovation potential. A heterogeneity analysis found that the effect of government data openness on CGLUE was more obvious in eastern cities, cities with higher levels of digital finance, and non-resource-based cities. In addition, open government data also reduced urban carbon emissions while improving CGLUE, contributing to China’s “double carbon” goal.
Assessing Appropriation of Space in Urban Green Spaces: Three Case Studies in Downtown Shanghai
Authors: Sant’Anna Marcus Vinicius , Zhou Wuzhong , Xu Yuanyuan
Published: November 2024

This study investigated patterns of activities in urban green spaces (UGSs) in downtown Shanghai. UGSs are essential public infrastructure, contributing to urban sustainability, quality of life, and social cohesion. Although widely studied, there is a gap in the literature regarding Chinese UGSs when the object of study is the nature the activities. In this sense, we aimed to investigate the activities from the perspective of appropriation of the space, considered here as different from the use of space. This study addressed this by analyzing user demographics, frequency, and spatial activity patterns to assess how these activities could be classified and scored according to a varying levels of appropriation. Through a mixed-methods design based on non-participant observation and behavior mapping, the study was conducted across three comprehensive parks in Shanghai, divided into nine observation zones. The data were analyzed through descriptive statistics, IBM SPSS, and qualitative coding, revealing, as the main findings, sixty distinct activity types, a soft to moderate level of appropriation, and notable variations in demographic presence and temporal trends. This research underscores the effectiveness of observational methods, validates appropriation as an analytical category, and emphasizes the importance of structured classification systems for improving the understanding of UGSs’ socio-spatial performance and their societal role.
Lipid Accumulation Product and Cardiometabolic Index as Effective Tools for the Identification of Athletes at Risk for Metabolic Syndrome
Authors: Di Gioia Giuseppe , Ferrera Armando , Celeski Mihail , Mistrulli Raffaella , Lemme Erika , Mango Federica , Squeo Maria Rosaria , Pelliccia Antonio
Published: November 2024

Introduction: Metabolic syndrome (MS) is a growing global public health concern that is associated with increased risk for cardiovascular events, even in athletes. The lipid accumulation product (LAP) index and cardiometabolic index (CMI) have been shown to be efficient markers of MS in the general population; its applicability in athletes has not been discussed yet. We aimed to assess the role of LAP and CMI in predicting MS in athletes. Methods: We retrospectively enrolled 793 Olympic athletes practicing different sporting disciplines (power, skill, endurance, and mixed), classified arbitrarily into no risk (NR), low risk (LR), high risk (HR), or MS if they had 0, 1, 2, or 3 criteria for MS, respectively. Evaluations included a calculation of the LAP index, CMI, anthropometric measurements, and clinical and laboratorial variables. Results: Among our population, only 0.8% reached the criteria for MS, 9.1% were at HR for MS, 37.8% were defined as LR, and 52.3% had NR. Significant differences in anthropometric parameters and the principal components of MS criteria (blood pressure, lipidic profile, glycemia) were reported predominantly in HR athletes and those with MS (p < 0.0001). LAP and CMI presented linearly increasing values from individuals with NR to those with MS (p < 0.0001). In addition, HR and MS athletes were classified as “likely MS” (9.8%) and LR and NR athletes as “unlikely MS” (90.2%). After adjusting for potential confounders, LAP ≥ 34.66 and CMI ≥ 0.776 emerged as independent predictors for MS in the overall cohort (Hazar Ratio (HR) 7.22 [3.75–13.89], p < 0.0001, and HR 5.37 [2.96–9.73], p < 0.0001, respectively). The ROC curve revealed that these cut-offs in the general population predict MS with an area under the curve (AUC) of 0.80 and 0.79, respectively, for LAP and CMI. However, gender-related cut-offs seem to be more precise in predicting MS (LAP ≥ 38.79 for male, LAP ≥ 14.16 for female, and CMI ≥ 0.881 for male and ≥0.965 for female). Conclusion: The ROC curve analyses of LAP and CMI showed good diagnostic accuracy in predicting MS among athletes, despite the low prevalence of MS in our sample. Thus, these indexes may be used to promote screening for primary prevention and early detection of athletes at risk for MS to establish an early prevention strategy. Larger prospective studies are necessary to validate their benefit in the general population.
Risk Factors Involved in Postural Disorders in Children and Adolescents
Authors: Dop Dalia , Pădureanu Vlad , Pădureanu Rodica , Niculescu Stefan-Adrian , Drăgoescu Alice Nicoleta , Moroșanu Aritina , Mateescu Diana , Niculescu Carmen Elena , Marcu Iulia Rahela
Published: November 2024

Postural disorders in children and adolescents have an increasing incidence. The aim of this study was to identify the type of postural defects in school-age and preschool children, as well as the external risk factors determined by an inadequate lifestyle. The research included 134 children aged between 5 and 18 years, in whom postural defects were identified. The project involved an examination of the children’s body posture, a survey of the parents to determine the children’s lifestyle, blood tests, and spinal X-rays. A significant percentage (76%) of the children included in the study were underweight. The examination of postural defects in the students revealed scoliosis in 21% of the patients, kyphosis in 7.5%, and lordosis in 1.5%, while 70% of the patients presented an association between at least two postural defects. As far as risk factors are concerned, we identified the presence of rickets sequelae in 70% of the patients, the presence of pectus excavatum in 43% of the patients, genu varum in 15%, and flat foot in 12%. Additionally, 90% of the children had an incorrect posture at the desk, while 42% incorrectly carried their backpack on one shoulder only. In terms of diet quality, associations between an inadequate diet and postural disorders were found for kyphosis, scoliosis, and other deformities. In conclusion, postural abnormalities in children have an increased incidence from an early age and are a result of the change in lifestyle in recent years, represented by sedentarism, a lack of physical activity, the excessive use of electronic devices, stress, and an inadequate diet.
Ginsenoside-Enriched Extract from Black Ginseng Anti-Fatigue Effects by Improving Antioxidant Capacity and Mitochondrial Function
Authors: Ge Shunji , Li Jiating , Tai Xueyue , Wang Kuo , Huang Liyan , Su Weixin , Zhang Guoqi , Zhong Bao , Li Fenglin
Published: November 2024

In this study, we investigated the anti-fatigue effects of black ginseng ginsenosides using exercise performance tests, serum analyses, and gene expression profiling. No significant differences in dietary intake or body weight were observed between groups. The low-dose black ginseng (LBG) group showed no significant improvements in swimming and rotating rod tests. In contrast, the medium (MBG)- and high-dose (HBG) groups showed notable increases in swimming time and significant improvements in the rotating rod test. All treatment groups exhibited longer running times, particularly the HBG group. Serum analysis revealed increased muscle and hepatic glycogen, catalase, and lactate dehydrogenase levels in the MBG and HBG groups, whereas lactate, lipid peroxide, and superoxide dismutase levels were decreased. Additionally, gene expression analysis showed significant upregulation of key antioxidant and mitochondrial function genes, including those encoding cationic amino acid transporter 2, stearoyl-CoA desaturase-2, nuclear respiratory factor 1, nuclear factor erythroid 2-related factor 2, mitochondrial transcription factor A, cytochrome c oxidase II, and NADH–ubiquinone oxidoreductase core subunit 1, particularly in the HBG group, indicating enhanced antioxidant capacity and improved mitochondrial function. These findings suggested that black ginseng ginsenosides effectively mitigated fatigue.
Post-Carotid Artery Stenting Hyperperfusion Syndrome in a Hypotensive Patient: Case Report and Systematic Review of Literature
Authors: Zupan Matija , Perovnik Matej , Pretnar Oblak Janja , Frol Senta
Published: November 2024

Cerebral hyperperfusion syndrome (CHS) is a serious post-procedural complication of carotid artery stenting (CAS). The pathophysiological mechanisms of CHS in the absence of arterial hypertension (AH) remain only partially understood. We performed a systematic literature search of the PubMed database using the terms »cerebral hyperperfusion syndrome«, »hypotension«, »hyperperfusion«, »stroke«, »intracranial hemorrhages«, »risk factors«, »carotid revascularization«, »carotid stenting«, »carotid endarterectomy«, »blood-brain barrier«, »endothelium«, »contrast encephalopathy«, and combinations. We present a case of a normotensive female patient who developed CHS post-CAS for symptomatic carotid stenosis while being hypotensive with complete recovery. We identified 393 papers, among which 65 were deemed relevant to the topic. The weighted average prevalence of CHS after CAS is 1.2% [0.0–37.7%] with that of intracranial hemorrhage (ICH) being 0.51% [0–9.3%]. Recently symptomatic carotid stenosis or contralateral carotid revascularization, urgent intervention, acute carotid occlusion, contralateral ≥70% stenosis, and the presence of leptomeningeal collaterals were associated with CHS. A prolonged hemodynamic instability after CAS conveys a higher risk for CHS. However, none of the articles mentioned isolated hypotension as a risk factor for CHS. Whereas mortality after ICH post-CAS ranges from 40 to 75%, in the absence of ICH, CHS generally carries a good prognosis. AH is not obligatory in CHS development. Even though impaired cerebral autoregulation and post-revascularization changes in cerebral hemodynamics seem to play a pivotal role in CHS pathophysiology, our case highlights the complexity of CHS, involving factors like endothelial dysfunction and sudden reperfusion. Further research is needed to refine diagnostic and management approaches for this condition.
Physicochemical Characterization and Kinetics Study of Polymer Carriers with Vitamin C for Controlled Release Applications
Authors: Bańkosz Magdalena
Published: November 2024

This study focuses on the selection and evaluation of a kinetic model for the release of vitamin C from different delivery systems, including microcapsules, hydrogels, and a hybrid system combining both. The microcapsules were synthesized from a 2% sodium alginate solution and with vitamin C incorporated in selected formulations. Hydrogels were obtained through photopolymerization using poly(ethylene glycol) diacrylate and polyvinyl alcohol, with and without the addition of vitamin C. The hybrid system incorporated the vitamin C-containing microcapsules within the hydrogel matrix. Physicochemical properties, such as density, porosity, and water vapor transmission rate (WVTR), were evaluated. Kinetic studies of vitamin C release were conducted under dynamic and static conditions, and the experimental data were fitted to six different kinetic models: zero-order, first-order, second-order, Higuchi, Korsmeyer–Peppas, and Hixson–Crowell. The Higuchi and Korsmeyer–Peppas models provided the best fit for most systems, indicating that the release is predominantly controlled by diffusion and, in dynamic conditions, swelling of the matrix. The hybrid system, while exhibiting slower release than the microcapsules and hydrogel alone, demonstrated more controlled and sustained release, which is advantageous for applications requiring prolonged action.
A Roadmap for the Certification of Polyurethane Flexible Connectors Used as Envelope Products in the Next Generation of Healthy, Nearly Zero-Energy Buildings
Authors: Nowak-Michta Aneta , Kwiecień Arkadiusz , Michta Jagoda
Published: November 2024

Currently, in the European Economic Area (EEA), producers of building materials are implementing innovative solutions that provide a chance for the widespread construction of zero-emission and zero-energy buildings. However, they encounter legal barriers related to the lack of standardization procedures enabling the rapid placement of innovative construction products on the market. The European project Horizon 2020: Measuring Envelope Products and Systems Contributing to the Next Generation of Healthy, Nearly Zero-Energy Buildings (MEZeroE) aims to support producers of innovative envelope products used in zero-energy buildings, including in the field of certification, CE (European Conformity), marking and placing them relatively quickly on the market. This article presents one of the research procedures developed and tested by Pilot Measurement & Verification Lines (PM&VL7) as part of the MEZeroE project for Flex&Robust polyurethane flexible connectors. This procedure considers the applicable legal requirements regarding CE marking and also indicates a certification path for this type of product.
Evaluation of Wear Resistance in Tungsten-Doped Diamond-like Carbon Coatings (WC/C) on Coated and Uncoated Surfaces Under Starved Oil Lubrication with R452A Refrigerant
Authors: Górny Kasper , Madej Monika , Stachowiak Arkadiusz
Published: November 2024

This article assesses the potential of using a diamond-like carbon coating doped with tungsten, a-C:H:W (WC/C), on the sliding pairs of refrigeration compressors. The ability of WC/C coating to provide low wear and a low coefficient of friction was experimentally verified in a specific refrigeration compressor operating environment (lubrication with oil diluted with refrigerant) and under extreme operating conditions (starved lubrication with a small amount of oil). Conditions of starved lubrication with a substance of reduced lubricity promote a temperature increase and high mechanical (friction) stresses on the surface of the sliding pairs. These situations can hinder the effective operation of WC/C coatings. Comparative wear tests were carried out for S235JR steel samples with and without WC/C coating. It was found that the samples with the WC/C coating had the lowest wear values and the lowest friction coefficients (approximately 0.06). A low coefficient of friction suggests that even a small amount of oil (one drop) is likely sufficient to achieve mixed lubrication conditions between the tested sliding surfaces and reduce material loss. The tested WC/C coating can protect sliding friction pairs in refrigeration compressors under extreme operating conditions caused by a lack of oil. Less friction reduces the need for energy to drive the refrigeration compressor. Additionally, the significance of this research is highlighted by the fact that the wear tests were conducted using R452A, a novel, eco-friendly refrigerant.
Effect of Carbon Black Content and Firing Atmosphere on the Properties and Microstructure of Al2O3-SiC-C Castables
Authors: Jia Quanli , Chen Jing , He Mantang , Sang Mengyang , Zhou Pingyi , Ma Haoxuan
Published: November 2024

Al2O3-SiC-C (ASC) castables containing spherical asphalt are widely utilized in high-temperature metallurgical furnaces because of their good abrasive resistance and slag resistance; however, the release of hazardous benzopyrene during the pyrosis process in spherical asphalt is detrimental to the environment and to the health of furnace workers. Herein, nontoxic nano carbon black (CB) was selected as the carbon source for ASC castables, and the effects of the CB amount and sintering atmosphere on the properties of ASC castables were investigated in this work. The results show that on increasing CB from 0.5% to 2%, the cold strength of the samples after firing in the reducing atmosphere increased, the residual strength increased, and the slag penetrated depth decreased; the reasons can be ascribed to nano CB being able to fill the pores to reduce the apparent porosity of the castables. Furthermore, SiC whiskers were formed at elevated temperatures and generated a network structure, which was beneficial in improving their properties. When CB was 1%, the cold modulus of the rupture of the samples after firing in the oxidizing atmosphere and reducing atmosphere were higher (about 20 MPa), the retained strength ratio of the samples pre-fired in the reducing atmosphere was the highest (85.4%), the hot strength at 1400 °C of the samples tested in the oxidized atmosphere was the highest (5.3 MPa), and the slag resistance of the samples measured in the oxidizing atmosphere was the best. The castables heat-treated in the air atmosphere possessed higher hot strength and slag resistance; the reasons can be attributed to the formed SiO2 derived from the oxidation of SiC, which reacted with Al2O3 to form mullite, creating a strengthening effect and decreasing the porosity and increasing the viscosity of slag, thereby improving the hot strength and slag resistance.
Construction of a MoOx/MoS2 Heterojunction via the Surface Sulfurization of the Oxide and Its Photocurrent-Switching Characteristics in the Range of the Broadband Light Spectrum
Authors: Ma Xingfa , Zhang Xintao , Gao Mingjun , Wang You , Li Guang
Published: November 2024

In order to utilize the longer wavelength light, the surface sulfurization of MoO3 was carried out. The photocurrent responses to typical 650, 808, 980, and 1064 nm light sources with Au gap electrodes were investigated. The results showed that the surface S–O exchange of MoO3 improved the interfacial charge transfer in the range of the broadband light spectrum. The S and O can be exchanged on the surface of MoO3 nanosheets under the hydrothermal condition, leading to the formation of a surface MoOx/MoS2 heterojunction. The interfacial interaction between the MoO3 nanosheets and MoS2 easily generated free electrons and holes, and it effectively avoided the recombination of photogenerated carriers. Meanwhile, the surface S-doping of MoO3 also resulted in the generation of an oxygen vacancy and sulfur vacancy on MoO3−xS2−y. The plasmonic characteristics of MoO3−x contributed to the enhancement of the interfacial charge transfer by photoexcitation. Otherwise, even with zero bias applied, a good photoelectric signal was still obtained with polyimide film substrates and carbon electrodes. This indicates that the formation of the heterojunction generates a strong built-in electric field that drives the photogenerated carrier transport, which can be self-powered. This study provides a simple and low-cost method for the surface functionalization of some metal oxides with a wide bandgap.
Ester-Modified Sodium Silicate Grout Material for Moraine Stabilization: Synthesis and Freeze-Thaw Resistance
Authors: Chen Chong , Wu Aixiang , Wang Shaoyong , Sun Wei , Gao Tong , Bai Longjian
Published: November 2024

To achieve effective consolidation of fine particles in moraine and enhance the freeze-thaw resistance of the consolidated body, this study developed a novel grouting material using sodium silicate, lipid-based curing agents, and acidic catalysts. The gelation time and rheological properties of this material were tested. The freeze-thaw resistance was studied through changes in uniaxial compressive strength (UCS) after freeze-thaw cycles, while the consolidation mechanism was analyzed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The experimental results indicate that the material’s gelation time can be controlled between 30s and 1600s, with an initial viscosity ranging from 5.9 to 9.8 mPa·s. Predictive models for these two indicators were established, and variance analysis revealed the influence ranking for gelation time: phosphoric acid dosage had the greatest effect, followed by EGDA content, with the Baume degree of sodium silicate having the least effect. The initial viscosity positively correlated with the Baume degree of sodium silicate and exhibited exponential growth over time. EGDA addition enhanced UCS by over 450%, reaching 1.2 MPa. During freeze-thaw cycles, strength degradation of the consolidated body was reduced by 10% to 30%. Microstructural tests showed that EGDA promotes silica gel formation and creates a network structure with unreacted sodium silicate, forming a dense consolidated body with moraine fine particles, thereby enhancing freeze-thaw resistance. These findings provide design references and theoretical support for moraine grouting in cold regions.
MXene/Bacterial Cellulose Hybrid Materials for Sustainable Soft Electronics
Authors: Guziewicz Wojciech , Srivatsa Shreyas , Zambrzycki Marcel , Dziadek Michał , Szatkowski Piotr , Szymczak Patryk , Berent Katarzyna , Marciszko-Wiąckowska Marianna , Radecka Marta , Kołodziejczyk Agata , Uhl Tadeusz
Published: November 2024

This work evaluated bacterial cellulose (BC) as a possible biodegradable soft electronics substrate in comparison to polyethylene terephthalate (PET), while also focusing on evaluating hybrid MXene/BC material as potential flexible electronic sensor. Material characterization studies revealed that the BC material structure consists of nanofibers with diameters ranging from 70 to 140 nm, stacked layer-by-layer. BC samples produced are sensitive to post-treatment with isopropanol resulting in a change of structural and mechanical properties. The viscoelastic properties of the BC substrates have been studied experimentally in comparison with the PET film. Aged BC substrate showcased similar viscoelastic properties stability, while exhibiting better properties above 70 °C, with total storage modulus change of −15% and loss modulus change of 21%. MXenes prepared using the Minimally Intensive Layer Delamination (MILD) method were screen-printed onto BC substrates and PET films to form MXene/BC (MX/BC) and MXene/PET (MX/PET) devices. The electrical properties results showcased different resistive behavior on both BC and PET substrate samples with different impedance moduli. MX/PET presented lower sheet resistance of around 156 Ω·sq−1, while MX/BC was 2733 Ω·sq−1. Finally, the MX/BC and MX/PET devices were subjected to repeatable quasi-static load tests and the piezoresistive sensing behavior of the devices has been reported.
Comparative Analysis of Mechanical and Morphological Properties of Cordenka and Ramie Fiber-Reinforced Polypropylene Composites
Authors: Ondiek Wycliffe , Ridzuan Amirul , Iwamoto Masaki , Macadre Arnaud , Goda Koichi
Published: November 2024

The depletion of conventional materials and their adverse environmental impacts have prompted a shift toward sustainable alternatives in composite materials engineering. In pursuit of this objective, this study investigated the mechanical properties of polypropylene matrix composites reinforced with Cordenka, an artificial cellulose fiber, and compared them to those reinforced with ramie, a natural cellulose fiber. Continuous strand composites were developed using the Multi-Pin-assisted Resin Infiltration (M-PaRI) process. The strands were subsequently sectioned into 15 mm lengths and injection-molded into dumbbell and strip specimens for mechanical characterization. The results showed that 20 wt% Cordenka/PP composites exhibited a tensile strength of 68.7 MPa, 2.04 times higher than neat PP and 1.66 times greater than the 20 wt% ramie/PP composites. Impact testing further demonstrated that Cordenka/PP composites absorbed 2 to 2.5 times more impact energy than ramie/PP composites, regardless of the presence of notches. Fiber length analysis indicated that Cordenka fibers maintained their length beyond the critical fiber length, allowing for efficient stress transfer and acting as a more effective reinforcement compared to ramie fibers, which were below this threshold. Consequently, the Cordenka/PP composites exhibited significantly enhanced mechanical performance. Scanning electron microscopy (SEM) analysis revealed fewer fiber pullouts in ramie-reinforced composites, suggesting superior interfacial adhesion to the PP matrix, although it did not translate to higher mechanical properties. These findings underscore the potential of Cordenka as a sustainable alternative to synthetic, non-biodegradable fibers in PP composites, providing improved mechanical properties and promising prospects for advanced composite applications.
The Machinability of Different Albromet W130 Plates Thicknesses by WEDM to the Required Surface Roughness Value
Authors: Mouralova Katerina , Benes Libor , Zahradnicek Radim , Fries Jiří , Manova Andrea
Published: November 2024

Wire Electrical Discharge Machining (WEDM) technology represents an unconventional but vital manufacturing technology in many different industrial branches. The automotive industry and its many significant requirements bring the need to manufacture inserts and mould segments for plastic injections from Albromet W130 material, with a required roughness, Ra, from 4.5 to 5 µm so that subsequent profile etching can be eliminated. A planned experiment of 60 rounds was carried out to discover the optimal machining parameters, namely, the pulse-off time, gap voltage, discharge current, pulse-on time, and wire speed in order for the thickness of 10 to 100 mm (after 10 mm) to demonstrate the required roughness. The goal was to evaluate the surface roughness, maximise the cutting speed, and manufacture it without surface or subsurface defects. The evaluation of the planned experiment led to the establishment of optimised WEDM machining parameters with which thicknesses of 10–100 mm will always be produced with the required roughness, Ra, from 4.5 to 5 µm and with the highest possible cutting speed. It was also proven that the machining does not lead to surface or subsurface defects, and thus, the service life of the manufactured parts will not be affected.
Compaction Evolution and Mechanisms of Granular Materials Due to Gyratory Shearing
Authors: Man Teng
Published: November 2024

Granular systems, no matter whether they are dry or saturated, are commonly encountered in both natural scenarios and engineering applications. In this work, we tackle the compaction problem of both dry and saturated granular systems under gyratory shearing compaction, where particles are subjected to constant pressure and continuous shear rate, which is quite different from the traditional cyclic shearing compaction. Such phenomena are crucial to the compaction of asphalt mixtures or soils in civil engineering and can be extended to other areas, such as powder processing and pharmaceutical engineering. In this study, we investigated the behavior of both dry and fully saturated mono-dispersed granular materials under gyratory shearing compaction using the discrete element method (DEM) and found that the gyratory speed or interstitial fluid viscosity has almost no impact on the compaction behavior, while the pressure and the particle size play more important roles. Additionally, it is the inertial time scale which dictates the compaction behavior under gyratory shearing in most cases; meanwhile, the viscous time scale can also have influence in some conditions. This work determines the similarity and unity between the granular gyratory compaction and the rheology of granular systems, which has direct relevance to various natural and engineering systems.
Design of a Thermal Performance Test Equipment for a High-Temperature and High-Pressure Heat Exchanger in an Aero-Engine
Authors: Yun Wongeun , Ha Manyeong , Kim Kuisoon , Lee Geesoo
Published: November 2024

For next-generation power systems, particularly aero-gas turbine engines, ultra-light and highly efficient heat exchangers are considered key enabling technologies for realizing advanced cycles. Consequently, the development of efficient and accurate aero-engine heat exchanger test equipment is essential to support future gas turbine heat exchanger advancements. This paper presents the development of a high-pressure and high-temperature (HPHT) heat exchanger test facility designed for aero-engine heat exchangers. The maximum temperature and pressure of the test facility were configured to simulate the conditions of the last-stage compressor of a large civil engine, specifically 1000 K and 5.5 MPa. These conditions were achieved using multiple electric heater systems in conjunction with an air compression system consisting of three turbo compressor units and a reciprocating compressor unit. A commissioning test was conducted using a compact tubular heat exchanger, and the results indicate that the test facility operates stably and that the measured data closely align with the predicted performance of the heat exchanger. A commissioning test of the tubular heat exchanger showed a thermal imbalance of 1.02% between the high-pressure (HP) and low-pressure (LP) lines. This level of imbalance is consistent with the ISO standard uncertainty of ±2.3% for heat dissipation. In addition, CFD simulation results indicated an average deviation of approximately 1.4% in the low-pressure outlet temperature. The close alignment between experimental and CFD results confirms the theoretical reliability of the test bench. The HPHT thermal performance test facility will be expected to serve as a critical test bed for evaluating heat exchangers for current and future gas turbine applications.
Proposed Multi-ST Model for Collaborating Multiple Robots in Dynamic Environments
Authors: Pham Hai Van , Do Huy Quoc , Nguyen Quang Minh , Asadi Farzin , Moore Philip
Published: November 2024

Coverage path planning describes the process of finding an effective path robots can take to traverse a defined dynamic operating environment where there are static (fixed) and dynamic (mobile) obstacles that must be located and avoided in coverage path planning. However, most coverage path planning methods are limited in their ability to effectively manage the coordination of multiple robots operating in concert. In this paper, we propose a novel coverage path planning model (termed Multi-ST) which utilizes the spiral-spanning tree coverage algorithm with intelligent reasoning and knowledge-based methods to achieve optimal coverage, obstacle avoidance, and robot coordination. In experimental testing, we have evaluated the proposed model with a comparative analysis of alternative current approaches under the same conditions. The reported results show that the proposed model enables the avoidance of static and moving obstacles by multiple robots operating in concert in a dynamic operating environment. Moreover, the results demonstrate that the proposed model outperforms existing coverage path planning methods in terms of coverage quality, robustness, scalability, and efficiency. In this paper, the assumptions, limitations, and constraints applicable to this study are set out along with related challenges, open research questions, and proposed directions for future research. We posit that our proposed approach can provide an effective basis upon which multiple robots can operate in concert in a range of ‘real-world’ domains and systems where coverage path planning and the avoidance of static and dynamic obstacles encountered in completing tasks is a systemic requirement.
Ensuring Driving and Road Safety of Autonomous Vehicles Using a Control Optimiser Interaction Framework Through Smart “Thing” Information Sensing and Actuation
Authors: Almutairi Ahmed , Asmari Abdullah Faiz Al , Alqubaysi Tariq , Alanazi Fayez , Armghan Ammar
Published: November 2024

Road safety through point-to-point interaction autonomous vehicles (AVs) assimilate different communication technologies for reliable and persistent information sharing. Vehicle interaction resilience and consistency require novel sharing knowledge for retaining driving and pedestrian safety. This article proposes a control optimiser interaction framework (COIF) for organising information transmission between the AV and interacting “Thing”. The framework relies on the neuro-batch learning algorithm to improve the consistency measure’s adaptability with the interacting “Things”. In the information-sharing process, the maximum extraction and utilisation are computed to track the AV with precise environmental knowledge. The interactions are batched with the type of traffic information obtained, such as population, accidents, objects, hindrances, etc. Throughout travel, the vehicle’s learning rate and the surrounding environment’s familiarity with it are classified. The learning neurons are connected to the information actuated and sensed by the AV to identify any unsafe vehicle activity in unknown or unidentified scenarios. Based on the risk and driving parameters, the safe and unsafe activity of the vehicles is categorised with a precise learning rate. Therefore, minor changes in vehicular decisions are monitored, and driving control is optimised accordingly to retain 7.93% of navigation assistance through a 9.76% high learning rate for different intervals.
Adaptive Multi-Scale Bayesian Framework for MFL Inspection of Steel Wire Ropes
Authors: Li Xiaoping , Sun Yujie , Liu Xinyue , Zhang Shaoxuan
Published: November 2024

Magnetic flux leakage (MFL) technology is widely used in steel wire rope (SWR) inspection for non-destructive testing. However, accurate defect characterization requires advanced signal processing techniques to handle complex noise conditions and varying defect types. This paper presents a novel adaptive multi-scale Bayesian framework for MFL signal analysis in SWR inspection. Our approach integrates discrete wavelet transform with adaptive thresholding and multi-scale feature fusion, enabling simultaneous detection of minute defects and large-area corrosion. To validate our method, we implemented a four-channel MFL detection system and conducted extensive experiments on both simulated and real-world datasets. Compared with state-of-the-art methods, including long short-term memory (LSTM), attention mechanisms, and isolation forests, our approach demonstrated significant improvements in precision, recall, and F1 score across various tolerance levels. The proposed method showed superior detection performance, with an average precision of 91%, recall of 89%, and an F1 score of 0.90 in high-noise conditions, surpassing existing techniques. Notably, our method showed superior performance in high-noise environments, reducing false positive rates while maintaining high detection sensitivity. While computational complexity in real-time processing remains a challenge, this study provides a robust solution for non-destructive testing of SWR, potentially improving inspection efficiency and defect localization accuracy. Future work will focus on optimizing algorithmic efficiency and exploring transfer learning techniques for enhanced adaptability across different non-destructive testing (NDT) domains. This research not only advances signal processing and anomaly detection technology but also contributes to enhancing safety and maintenance efficiency in critical infrastructure.
Polarizing Magnetic Field Effect on Some Electrical Properties of a Ferrofluid in Microwave Field
Authors: Marin Catalin N. , Fannin Paul C. , Malaescu Iosif
Published: November 2024

The complex dielectric permittivity, ε (f, H) = ε′ (f, H) − i ε″ (f, H), in the microwave frequency range f, of (0.1–3) GHz and polarizing field values H, in the range of (0–135) kA/m, was measured for a kerosene-based ferrofluid with magnetite particles. A relaxation process attributed to interfacial type relaxation was highlighted, determining for the first time in the microwave field, the activation energy of the dielectric relaxation process in the presence of the magnetic field, EA(H), in relation to the activation energy in zero field, EA(H = 0). Based on the complex permittivity measurements and the Claussius–Mossotti equation, the dependencies on frequency (f), and magnetic field (H), of the polarizability (α) and electrical conductivity (σ), were determined. From the dependence of α(f,H), the electric dipolar moment, p, of the particles in the ferrofluid, was determined. The conductivity spectrum, σ(f,H), was found to be in agreement with Jonscher’s universal law and the electrical conduction mechanism in the ferrofluid was explained using both Mott’s VRH (variable range hopping) model and CBH (correlated barrier hopping) model. Based on these models and conductivity measurements, the hopping distance, Rh, of the charge carriers and the maximum barrier height, Wm, for the investigated ferrofluid was determined for the first time in the microwave field. Knowledge of these electrical properties of the ferrofluid in the microwave field is useful for explaining the mechanisms of polarization and control of electrical conductivity with an external magnetic field, in order to use ferrofluids in various technological applications in microwave field.
Mathematical Analysis for Honeybee Dynamics Under the Influence of Seasonality
Authors: El Hajji Miled , Alzahrani Fahad Ahmed S. , Alharbi Mohammed H.
Published: November 2024

In this paper, we studied a mathematical model for honeybee population diseases under the influence of seasonal environments on the long-term dynamics of the disease. The model describes the dynamics of two different beehives sharing a common space. We computed the basic reproduction number of the system as the spectral radius of either the next generation matrix for the autonomous system or as the spectral radius of a linear integral operator for the non-autonomous system, and we deduced that if the reproduction number is less than unity, then the disease dies out in the honeybee population. However, if the basic reproduction number is greater than unity, then the disease persists. Finally, we provide several numerical tests that confirm the theoretical findings.
Copula-Based Regression with Mixed Covariates
Authors: Aldahmani Saeed , Kortbi Othmane , Mesfioui Mhamed
Published: November 2024

In this paper, we focused on developing copula-based modeling procedures that effectively capture the dependence between response and explanatory variables. Building upon the work of Noh et al. (J. Am. Stat. Assoc. 2013, 108, 676–688) we extended copula-based regression to accommodate both continuous and discrete covariates. Specifically, we explored the construction of copulas to estimate the conditional mean of the response variable given the covariates, elucidating the relationship between copula structures and marginal distributions. We considered various estimation methods for copulas and distribution functions, presenting a diverse array of estimators for the conditional mean function. These estimators range from non-parametric to semi-parametric and fully parametric, offering flexibility in modeling regression relationships. An adapted algorithm is applied to construct copulas and simulations are carried out to replicate datasets, estimate prediction model parameters, and compare with the OLS method. The practicality and efficacy of our proposed methodologies, grounded in the principles of copula-based regression, are substantiated through methodical simulation studies.
Fast Prediction of Characteristics in Wound Rotor Synchronous Condenser Using Subdomain Modeling
Authors: Nguyen Manh-Dung , Kim Tae-Seong , Shin Kyung-Hun , Jang Gang-Hyeon , Choi Jang-Young
Published: November 2024

Wound rotor synchronous condensers (WRSCs) are DC-excited rotor machines that utilize rotor winding instead of permanent magnets. Their voltage regulator controls the rotor field to generate or absorb reactive power, thereby regulating grid voltage or improving power factor. A key characteristic of a WRSC is the compounding curve, which shows the required rotor current under specific stator current and voltage conditions. This paper presents an approach for quickly calculating the electromagnetic parameters of a WRSC using a mathematical method. After determining magnetic flux density, induced voltage, and inductance through analytical methods, the Park and Clarke transformations are applied to derive the dq-frame quantities, enabling prediction of active and reactive powers and compounding curve characteristics. The 60 Hz model was evaluated through comparison with finite element method (FEM) simulations. Results of flux density, induced voltage, and the compounding curve under varying rotor and stator current conditions showed that the proposed method achieved comparable performance to FEM simulation while reducing computational time by half.
Almost Periodic Solutions of Differential Equations with Generalized Piecewise Constant Delay
Authors: Chiu Kuo-Shou
Published: November 2024

In this paper, we investigate differential equations with generalized piecewise constant delay, DEGPCD in short, and establish the existence and stability of a unique almost periodic solution that is exponentially stable. Our results are derived by utilizing the properties of the (μ1,μ2)-exponential dichotomy, Cauchy and Green matrices, a Gronwall-type inequality for DEGPCD, and the Banach fixed point theorem. We apply these findings to derive new criteria for the existence, uniqueness, and convergence dynamics of almost periodic solutions in both the linear inhomogeneous and quasilinear DEGPCD systems through the (μ1,μ2)-exponential dichotomy for difference equations. These results are novel and serve to recover, extend, and improve upon recent research.
Transcriptomics and Metabolomics Explain the Crisping Mechanisms of Broad Bean-Based Crisping Diets on Nile Tilapia (Orechromis niloticus)
Authors: He Xiaogang , Shu Haoming , Xu Tian , Yu Minhui , Li Honglin , Hu Yanru , Mo Jiajun , Ai Chunxiang
Published: November 2024

Background/Objectives: To investigate the crisping mechanism of broad bean-based crisping diets on Nile Tilapia. Methods: Four crisping diets were designed to feed 360 fish for 90 days, and multiomics analyses were employed. Results: Our results indicated that the designed crisping diets for Nile tilapia can effectively make tilapia muscle crispy. The ingestion of broad bean-based diets induced metabolic reprogramming dominated by glycolytic metabolism inhibition in fish, and metabolic reprogramming is the initiator of muscle structural remodeling. Among these, glucose is the main DAMP to be recognized by cellular PRRs, activating further immune response and oxidative stress and finally resulting in muscle change. Conclusions: Based on our results of multiomics, pck2, and ldh played main roles in crisping molecular mechanisms in driving the initial metabolic reprogram. Moreover, the addition of the crisping package further activated the ErbB signaling pathway and downstream MAPK signaling pathway to strengthen immune response, promoting muscle fiber development and growth. Our study delved into the effects of crisping formula diet on the liver of Nile tilapia at the molecular level, providing theoretical guidance for the nutritional regulation of crispy Nile tilapia.
A Simple Pump-Free Approach to Generating High-Throughput Microdroplets Using Oscillating Microcone Arrays
Authors: Yetiskin Erturan , Erdem Ilayda , Gucluer Sinan , Ozcelik Adem
Published: November 2024

Droplet generation is crucial in various scientific and industrial fields, such as drug delivery, diagnostics, and inkjet printing. While microfluidic platforms enable precise droplet formation, traditional methods often require costly and complex setups, limiting their accessibility. This study introduces a simple, low-cost approach using an off-the-shelf unit and a 3D-printed reservoir. The device, equipped with a driver board, piezo-ring transducer, and a metal sheet with holes, generates oil-in-water (O/W) droplets with an average diameter of 4.62 ± 0.67 µm without external fluid pumps. Its simplicity, cost-effectiveness, and scalability make it highly suitable for both lab-on-chip and industrial applications, demonstrating the feasibility of large-scale uniform droplet production.
In Situ Potentiometric Monitoring of Nitrate Removal from Aqueous Solution by Activated Carbon and Ion Exchange Resin
Authors: Olmos José Manuel , Gil Lucía , Ortuño Joaquín Ángel
Published: November 2024

A nitrate selective electrode was used for real-time in situ potentiometric monitoring of a batch nitrate removal process using activated carbon and ion exchange resin. A plasticized polymeric membrane consisting of polyvinyl chloride, 2-nitrophenyl octyl ether and tridodecyl methyl ammonium chloride was incorporated into an ion-selective electrode body. First, the dynamic potential response of the electrode to nitrate was investigated. Two commercial activated carbons with different physical properties were then tested. Nitrate removal with these carbons was monitored potentiometrically using several nitrate concentrations. The extreme turbidity of the solutions was not a drawback during potentiometric monitoring of the process, which is a clear advantage over other methods such as optical monitoring. The potential versus time recordings were converted into nitrate concentration versus time plots, which were evaluated with different adsorption kinetic models. A pseudo-second order kinetic model for nitrate adsorption on both activated carbons was found to fit the experimental data very well. The values of the kinetic parameters were very different between the two activated carbons. The proposed methodology was also satisfactorily applied to the study of nitrate removal by an ion exchange resin. In this case, the experimental results clearly follow a pseudo-first order kinetic model. Potential applications of the proposed methodology for monitoring nitrate removal in real water samples are discussed.