bluuebunny/crossref_metadata_2025 huggingface dataset:
The Application of Precision Medicine in Structural Heart Diseases: A Step towards the Future
Authors: Chrysostomidis Grigorios , Apostolos Anastasios , Papanikolaou Amalia , Konstantinou Konstantinos , Tsigkas Grigorios , Koliopoulou Antigoni , Chamogeorgakis Themistokles
Published: March 2024

The personalized applications of 3D printing in interventional cardiology and cardiac surgery represent a transformative paradigm in the management of structural heart diseases. This review underscores the pivotal role of 3D printing in enhancing procedural precision, from preoperative planning to procedural simulation, particularly in valvular heart diseases, such as aortic stenosis and mitral regurgitation. The ability to create patient-specific models contributes significantly to predicting and preventing complications like paravalvular leakage, ensuring optimal device selection, and improving outcomes. Additionally, 3D printing extends its impact beyond valvular diseases to tricuspid regurgitation and non-valvular structural heart conditions. The comprehensive synthesis of the existing literature presented here emphasizes the promising trajectory of individualized approaches facilitated by 3D printing, promising a future where tailored interventions based on precise anatomical considerations become standard practice in cardiovascular care.
Exploring Fracture Patterns: Assessing Representation Methods for Bone Fracture Simulation
Authors: Pérez-Cano Francisco Daniel , Parra-Cabrera Gema , Vilchis-Torres Ivett , Reyes-Lagos José Javier , Jiménez-Delgado Juan José
Published: March 2024

Fracture pattern acquisition and representation in human bones play a crucial role in medical simulation, diagnostics, and treatment planning. This article presents a comprehensive review of methodologies employed in acquiring and representing bone fracture patterns. Several techniques, including segmentation algorithms, curvature analysis, and deep learning-based approaches, are reviewed to determine their effectiveness in accurately identifying fracture zones. Additionally, diverse methods for representing fracture patterns are evaluated. The challenges inherent in detecting accurate fracture zones from medical images, the complexities arising from multifragmentary fractures, and the need to automate fracture reduction processes are elucidated. A detailed analysis of the suitability of each representation method for specific medical applications, such as simulation systems, surgical interventions, and educational purposes, is provided. The study explores insights from a broad spectrum of research articles, encompassing diverse methodologies and perspectives. This review elucidates potential directions for future research and contributes to advancements in comprehending the acquisition and representation of fracture patterns in human bone.
Mechanical Ventilation, Retinal Avascularity and Rate of Vascularisation: A Triad of Predictors for Retinopathy of Prematurity Treatment
Authors: Protsyk Olena , García Serrano José Luis
Published: March 2024

Aim: The temporal avascular area of the retina and the duration of mechanical ventilation (DMV) may predict the need to treat retinopathy of prematurity (ROP). This study considers whether the rate of retinal vascularisation and related risk factors should be included in a predictive model of the need for ROP treatment. Methods: This single-centre, observational retrospective case–control study was conducted on 276 preterm infants included in an ROP screening programme. All had undergone at least three examinations of the fundus. The main outcome measures considered were DMV (in days of treatment), the temporal avascular area (in disc diameters, DD) and the rate of temporal retinal vascularisation (DD/week). Results: The multivariate logistic model that best explains ROP treatment (R2 = 63.1%) has three significant risk factors: each additional day of mechanical ventilation (OR, 1.05 [95% CI, 1.02–1.09]; p = 0.001); each additional DD of temporal avascular area (OR, 2.2 [95% CI, 1.7–2.9]; p < 0.001) and a vascularisation rate <0.5 DD/week (OR, 19.0 [95% CI, 6.5–55.5]; p < 0.001). Two tables are presented for calculating the expected need for ROP treatment according to these three risk factors. Conclusions: A greater DMV, a broad avascular area of the temporal retina at the first binocular screening and slow retinal vascularisation strongly predict the need for ROP treatment. The predictive model we describe must be validated externally in other centres.
Approximating Option Greeks in a Classical and Multi-Curve Framework Using Artificial Neural Networks
Authors: du Plooy Ryno , Venter Pierre J.
Published: March 2024

In this paper, the use of artificial neural networks (ANNs) is proposed to approximate the option price sensitivities of Johannesburg Stock Exchange (JSE) Top 40 European call options in a classical and a modern multi-curve framework. The ANNs were trained on artificially generated option price data given the illiquid nature of the South African market, and the out-of-sample performance of the optimized ANNs was evaluated using an implied volatility surface constructed from published volatility skews. The results from this paper show that ANNs trained on artificially generated input data are able to accurately approximate the explicit solutions to the respective option price sensitivities of both a classical and a modern multi-curve framework in a real-world out-of-sample application to the South African market.
Community-Scale Classification and Governance Policy Implications for Demographic, Economic, and Land-Use Linkages in Mega-Cities
Authors: Mao Yonghong , Fan Jie , Zhou Daojing , He Yao , Yuan Meng , Zhang Huixin
Published: March 2024

Analyzing the spatio-temporal relationship between socio-economics and land-use structure at the micro-scale is crucial for effective spatial governance in large cities. This paper focuses on Beijing, utilizing long time-series remote sensing images and multi-source data spanning 30 years. We employ spatio-temporal clustering based on kilometer grid cells and a community-scale multi-factor aggregation method to categorize the linkages and spatio-temporal matching of population, GDP, land development, and ecological protection at the community level in a problem-oriented approach. Results indicate significant changes in Beijing’s population, GDP, and land use, with a 11.53% increase in land development intensity. We identify significant temporal and spatial disparities between population–GDP dynamics, population–land development trends, and GDP–land development patterns, underscoring the multifaceted challenges inherent in urban governance. Areas characterized by lagging population concentration, sluggish economic growth, rampant land development, and ecological fragility collectively encapsulate notable portions of Beijing’s expansive urban terrain. Mismatches pose governance risks, with medium to high-risk communities comprising 18.08% of community units and high-risk types representing 4.27% in Beijing. These discrepancies pose formidable governance risks, with communities ranging from moderate to high-risk categories, necessitating tailored interventions to address their unique challenges. This systematic exploration of comprehensive governance issues within mega-cities promises to furnish decision-makers with invaluable insights, facilitating nuanced and strategic urban governance approaches tailored to the intricacies of urban dynamics and challenges.
Spatial Pattern and Coordination Relationship of Production–Living–Ecological Space Function and Residents’ Behavior Flow in Rural–Urban Fringe Areas
Authors: Sun Xiaochen , Zhang Bingzi , Ye Shuni , Grigoryan Sara , Zhang Yazhuo , Hu Yike
Published: March 2024

Territorial spatial planning requires thoughtful consideration of the scientific layout and synergistic control of production, living, and ecological spaces (PLESs). However, research in this field often neglects the human perspective and fails to account for people’s demands and behavioral characteristics. This study evaluates the level and spatial characteristics of residents’ production, living, and ecological behavioral (PLEB) flow, as well as the spatial pattern of the PLES functions, within the framework of the human–land coupling system. Therefore, to analyze the behavior–space coupling coordination relationship, the coupling coordination model is applied. The results indicate that the overall level of residents’ PLEB flow in rural–urban fringe areas is at a lower middle level and the functionality of the PLES is at a medium level, with a spatial distribution pattern of high in the northern and low in the southern areas. Most of the behavior–space matching types are in a state of mismatch between supply and demand. Meanwhile, the PLEB–PLES coupling coordination relationship is generally unbalanced, which is particularly noticeable in the production space. Regardless of whether the behavior–space matching type is a supply deficit or a supply surplus, the mismatch between supply and demand leads to uncoordinated and unreasonable spatial utilization. Overall, the findings of the study provide guidance for future research endeavors about PLESs and suggest embracing a human-centered scientific paradigm. Such a paradigm can promote high-quality, sustainable development of territorial spatial planning while strengthening the capacity and effectiveness of spatial governance and control.
Spatial Downscaling of Precipitation Data in Arid Regions Based on the XGBoost-MGWR Model: A Case Study of the Turpan–Hami Region
Authors: He Huanhuan , Wang Jinjie , Ding Jianli , Wang Lei
Published: March 2024

Accurate and reliable precipitation data are important for analyzing regional precipitation distribution, water resource management, and ecological environment construction. Due to the scarcity of meteorological stations in the Turpan–Hami region, precipitation observation conditions are limited, and it is difficult to obtain precipitation data. Firstly, the applicability of TRMM 3B43v7, GPM_3IMERGM 06, and CMORPH CDR satellite precipitation data for the Turpan–Hami Region was evaluated, and the products with better applicability were selected. Next, the Extreme Gradient Boosting Algorithm (XGBoost) and the Shapley Additive Explanations for Machine Learning (SHAP) model were combined to carry out a feature importance analysis on the climate factors affecting precipitation (mean temperature, actual evapotranspiration, wind speed, cloud cover), from which climate factors with a greater influence on precipitation were selected. Combined with climate factors, normalized difference vegetation index (NDVI), slope, aspect, and elevation as explanatory variables, a Multi-Scale Geographically Weighted Regression (MGWR) model was constructed to obtain the monthly precipitation data of 1 km spatial resolution in the Turpan–Hami area from 2001 to 2020. Finally, the spatiotemporal distribution characteristics and changing trend of precipitation in the Turpan–Hami region from 2001 to 2020 were analyzed. The results show that (1) GPM_3IMERGM 06 satellite precipitation data exhibits good applicability in the Turpan–Hami region. (2) The precision verification of the downscaling results from a monthly scale and an annual scale shows that the accuracy and spatial resolution of the data are improved after downscaling. (3) From 2001 to 2020, the precipitation in the Turpan–Hami region showed an insignificantly increasing trend.
Evolutionary Echoes: A Four-Day Fasting and Low-Caloric Intake Study on Autonomic Modulation and Physiological Adaptations in Humans
Authors: Belinchón-deMiguel Pedro , Navarro-Jiménez Eduardo , Laborde-Cárdenas Carmen Cecilia , Clemente-Suárez Vicente Javier
Published: March 2024

This study evaluates the psychophysiological response to a simulated hunter–gatherer endurance task with restricted caloric intake over four days. It assesses changes in body composition, autonomic modulation, and physical and cognitive performance. Participants underwent daily 8 h fasted walks followed by a 150 kcal meal to replicate hunter–gatherer activity and dietary patterns. Measurements of metabolic, respiratory, and subjective well-being, along with heart rate variability (HRV) monitoring, were conducted pre- and post-activity to evaluate the impact of endurance activity under caloric restriction. We found weight loss, decreased body and visceral fat, and reduced skeletal muscle mass and water percentage. High sympathetic activation and stable urinary markers, except for increased proteinuria, indicated stress responses and muscular degradation. Elevated perceived exertion post-exercise with good adaptation to prolonged effort underlines the body’s adaptability to ancestral lifestyle conditions, highlighting the connection among endurance, nutrition, and psychophysiological health.
The Influence of Tumor-Specific Markers in Breast Cancer on Other Blood Parameters
Authors: Varzaru Vlad Bogdan , Eftenoiu Anca-Elena , Vlad Daliborca Cristina , Vlad Cristian Sebastian , Moatar Aurica Elisabeta , Popescu Roxana , Cobec Ionut Marcel
Published: March 2024

Background: Breast cancer is the most frequently diagnosed cancer among women, responsible for the highest number of cancer-related deaths worldwide. There is limited data available related to serum tumor markers in breast cancer and other blood parameters or other glandular laboratory parameters. This study aims to evaluate the correlation of tumor-specific markers for breast cancer with other blood parameters and how these correlations could impact clinical management. Material and Method: This retrospective study represents a data analysis from 1 January 2020 to 31 May 2023, in the County Hospital of Timisoara, Romania. We reviewed all the cases where, in the laboratory analyses, the serum tumor specific biomarkers for breast cancer were analyzed. Results: A statistical analysis was performed in order to identify a possible relationship between CA 15-3 and the various biomarkers and blood parameters included in the present study. Values were classified according to reference ranges. The tests revealed no statistically significant associations between CA 15-3 values and the levels of CA125 (χ2(1) = 1.852, p = 0.174), CEA (χ2(1) = 1.139, p = 0.286), AFP (Fisher’s exact test, p = 0.341), fT4 (Fisher’s exact test, p = 0.310), TSH (Fisher’s exact test, p = 0.177), or PTH (Fisher’s exact test, p = 0.650). Conclusion: The findings indicate a lack of strong correlation between CA 15-3 and CA125, CEA, AFP, thyroid function markers, or PTH within this cohort.
The Effects of the Lubricant Properties and Surface Finish Characteristics on the Tribology of High-Speed Gears for EV Transmissions
Authors: Zhmud Boris , Najjari Morteza , Brodmann Boris
Published: March 2024

Electric vehicle (EV) transmissions operate at high speeds. High-speed operation puts higher demands on bearings, seals, and gears. Bearings in EV transmissions are prone to electrically induced bearing damage and may exhibit signs of pitting and fluting. Surface-initiated rolling contact fatigue is another common problem gaining increased attention lately. Most EV transmissions require a coupling between an oil-lubricated gearbox to an electrical motor that runs with minimal lubrication at very high rpm. The high mechanical and thermal stresses the seals are exposed to under starved lubrication conditions have a detrimental impact on their service life. Hence, proper lubrication is critical. In general, EV transmission fluids call for a somewhat different spectrum of properties compared to conventional ATFs. Gear tribology simulations open new ways to the design and optimization of lubrication for EV transmissions. Additionally, such simulations can also provide valuable insights into the effects of different oil properties on cooling and lubrication efficiencies, thereby helping in matching the lubricant and hardware characteristics for optimal performance. In the present communication, we demonstrate the effects of different lubricants and surface finishing technologies on the tribology of high-speed gears using tribological tests and advanced thermal elastohydrodynamic (TEHD) simulations. The important roles of lubricity additives and surface finish optimization are highlighted in conjunction with a move towards ultralow viscosity EV transmission fluids.
Deterioration Mechanism and Status Prediction of Hydrocarbon Lubricants under High Temperatures and Humid Environments
Authors: Su Rui , Cao Wei , Jin Zili , Wang Yifan , Ding Letian , Maqsood Muhammad , Wang Dong
Published: March 2024

In practical engineering applications, high temperatures and water ingress seriously affect the service life of hydrocarbon lubricants. In this study, the deterioration process of hydrocarbon lubricants under high temperatures and humid environments was investigated, and a new health state prediction model was proposed. Simulation of hydrocarbon lubricant Polyalpha−olefin (PAO) molecules used the ReaxFF force field to analyse the high temperature thermal oxidation process of lubricants. The rheological properties of oil−water emulsions were determined by observing the morphology of oil−water two−phase mixtures with different water contents. A multiparameter fusion viscosity prediction model was proposed using a linear model of the viscosity of aqueous fluids, as affected by temperature and water content, and was fitted with the Andrade viscosity−temperature equation to predict lubricant viscosity changes under multiple parameters. Online validation tests were carried out on a compound planetary transmission system, and the surface topographical parameters of the transmission components were further discussed. Experimental results show that the linear correlation with the improved lubricant viscosity prediction model is 0.966, and the surface wear of transmission components is consistent with the trend of lubricant quality change. These findings provide a fundamental basis for the assessment of lubricant service life in high temperatures and humid environments.
Physics of the Sub-Monolayer Lubricant in the Head-Disk Interface
Authors: Ono Kyosuke
Published: March 2024

This review presents a series of studies which have demonstrated that the diffusion characteristics of rarefied mobile lubricant films used in modern magnetic disks can be evaluated by a novel diffusion theory based on continuum mechanics, and that the meniscus force of the rarefied film is the major interaction force at the head-disk interface. The limitations of the conventional diffusion and disjoining pressure equations are first shown, and diffusion and disjoining pressure equations for rarefied liquid films are proposed, showing that the diffusion coefficient is in good agreement with the experiment. The experiment, in which glass spheres with radii of 1 and 2 mm collided with magnetic disks of different film thicknesses, showed that attraction similar to the pull-off forces of a static meniscus was measured only at the separation. Furthermore, mathematical analysis of the elastic meniscus contact between a sphere and a plane with a submonolayer liquid film showed that the maximum adhesion force is equal to the meniscus pull-off force and that the contact characteristics become similar to those of the JKR theory as the liquid film thickness decreases. A basic physical model of submonolayer liquid film is also proposed to justify the continuum mathematical equations.
Mechanical and Durability Characterization of Hybrid Recycled Aggregate Concrete
Authors: Hameed Rashid , Tahir Muhammad , Abbas Safeer , Sheikh Haseeb Ullah , Kazmi Syed Minhaj Saleem , Munir Muhammad Junaid
Published: March 2024

The recycling of construction and demolition waste (CDW) for the extraction of recycled concrete aggregates (RCAs) to be used to produce recycled aggregate concrete (RAC) is widely acknowledged internationally. However, CDW not only contains concrete debris but may also contain burnt clay bricks. The recycling of such CDW without the segregation of different components would result in recycled aggregates having different proportions of concrete and brick aggregates. The utilization of these aggregates in concrete requires a detailed investigation of their mechanical and durability properties. In this regard, the present study focused on investigating the mechanical and durability properties of hybrid recycled aggregate concrete (HRAC) made by the 100% replacing of natural aggregates with recycled brick (RBAs) and RCA in hybrid form. The partial replacement of cement with fly ash was also considered to reduce the corban footprint of concrete. An extensive experimental program was designed and carried out in two phases. In the first phase, a total of 48 concrete mixes containing coarse RBA and RCA in mono and hybrid forms were prepared and tested for their compressive strength. The test results indicated that the compressive strength of HRAC is greatly affected by the proportion of coarse RBA and RCA. In the second phase, based on the results of the first phase, eight concrete mixes with the most critical proportions of RBA and RCA in hybrid form were selected to evaluate their mechanical and durability performance. In addition, four mixes with natural aggregates were also prepared for comparison purposes. To evaluate the mechanical properties of the concrete mixes, compressive strength and modulus of rupture (MOR) tests were performed, while for the evaluation of durability properties, water absorption and behavior after exposure to aggressive conditions of acidic and brine solutions were studied. The results revealed that a 20% replacement of cement with fly ash resulted in acceptable mechanical and durability properties of HRAC intended to be used for making concrete bricks or pavers.
La-Doped Sm2Zr2O7/PU-Coated Leather Composites with Enhanced Mechanical Properties and Highly Efficient Photocatalytic Performance
Authors: Chen Liliang , Li Weiguo , Hou Xianbo , Feng Gang
Published: March 2024

Flexible La-doped Sm2Zr2O7/polyurethane (PU) coated leather composites were synthesized using a one-step hydrothermal method, with highly efficient photocatalytic degradation properties by coating the La-doped Sm2Zr2O7/PU emulsion onto the leather and drying it. The phase composition and optical properties of the as-prepared photocatalytic material were systematically characterized. The result revealed that La was doped in Sm2Zr2O7 successfully, and the prepared samples still possessed pyrochlore structure. The absorption edge of the prepared samples exhibited a red-shift with the increase in La doping, indicating that La doping could broaden the absorbance range of the La-doped Sm2Zr2O7 materials. The catalytic performance of La-doped Sm2Zr2O7/PU composite emulsion coating on the photocatalytic performance of leather was studied with Congo red solution as the target pollutant. The results showed that the best photocatalytic property was found in the 5% La-doped Sm2Zr2O7 nanomaterial at a concentration of 3 g/L. The resulting 5% La-doped Sm2Zr2O7 nanomaterial exhibited a high specific surface area of 73.5 m2/g. After 40 min of irradiation by a 450 W xenon lamp, the degradation rate of Congo red reached 93%. Moreover, after surface coating, the La-doped Sm2Zr2O7/PU coated leather composites showed obviously improved mechanical properties, as the tensile strength of La-doped Sm2Zr2O7/PU coated leather composites increased from 6.3 to 8.4 MPa. The as-prepared La-doped Sm2Zr2O7/PU coated leather composites with enhanced mechanical properties and highly efficient photocatalytic performance hold promising applications in the treatment of indoor volatile organic compounds.
Multi-Mode Damage and Fracture Mechanisms of Thin-Walled Tubular Parts with Cross Inner Ribs Manufactured via Flow Forming
Authors: Zeng Xiang , Huang Leheng , Fan Xiaoguang , Li Hongwei , Zhan Mei , Mi Zhongbao , Xu Xuefeng , Fan Yubin
Published: March 2024

In order to study the multi-mode damage and fracture mechanisms of thin-walled tubular parts with cross inner ribs (longitudinal and transverse inner ribs, LTIRs), the Gurson–Tvergaard–Needleman (GTN) model was modified with a newly proposed stress state function. Thus, tension damage and shear damage were unified by the new stress state function, which was asymmetric with respect to stress triaxiality. Tension damage dominated the modification, which coupled with the shear damage variable, ensured the optimal prediction of fractures of thin-walled tubular parts with LTIRs by the modified GTN model. This included fractures occurring at the non-rib zone (NRZ), the longitudinal rib (LIR) and the interface between the transverse rib (TIR) and the NRZ. Among them, the stripping of material from the outer surface of the tubular part was mainly caused by the shearing of built-up material in front of the rollers under a large wall thickness reduction (ΔT). Shear and tension deformation were the causes of fractures occurring at the NRZ, while axial tension under a large TIR interval (l) mainly resulted in fractures on LIRs. Fractures at the interface between the TIR and NRZ were due to the shearing applied by rib grooves and radial tension during the formation of ribs. This study can provide guidance for the manufacturing of high-performance aluminum alloy thin-walled tubular components with complex inner ribs.
Innovative Cellular Insulation Barrier on the Basis of Voronoi Tessellation—Influence of Internal Structure Optimization on Thermal Performance
Authors: Anwajler Beata , Zielińska Sara , Witek-Krowiak Anna
Published: March 2024

The optimization of structure and thermal properties in 3D-printed insulation materials remains an underexplored area in the literature. This study aims to address this gap by investigating the impact of 3D printing on the thermal properties of manufactured cellular composites. The materials studied were closed-cell foams with a complex cell structure based on the Voronoi cell model, manufactured using incremental technology (3D printing). The influence of the cellular structure of the composite, the type of material used, and the number of layers in the composite structure on its thermal properties, i.e., thermal conductivity coefficient, thermal resistance, and coefficient of heat transfer, was analyzed. Samples of different types of thermosetting resins, characterized by different values of emissivity coefficient, were analyzed. It was shown that both the type of material, the number of layers of the composite, and the number of pores in its structure significantly affect its thermal insulating properties. Thermal conductivity and permeability depended on the number of layers and decreased up to 30% as the number of layers increased from one to four, while thermal resistance increased to 35%. The results indicate that material structure is key in regulating thermal conduction. Controlling the number of cells in a given volume of composite (and thus the size of the air cells) and the number of layers in the composite can be an effective tool in designing materials with high insulation performance. Among the prototype composites produced, the best thermal performance was that of the metalized four-layer cellular composites (λ = 0.035 ± 0.002 W/m·K, Rc = 1.15 ± 0.02 K·m2/W, U = 0.76 ± 0.01 W/m2·K).
Online Detection of Laser Welding Penetration Depth Based on Multi-Sensor Features
Authors: She Kun , Li Donghui , Yang Kaisong , Li Mingyu , Wu Beile , Yang Lijun , Huang Yiming
Published: March 2024

The accurate online detection of laser welding penetration depth has been a critical problem to which the industry has paid the most attention. Aiming at the laser welding process of TC4 titanium alloy, a multi-sensor monitoring system that obtained the keyhole/molten pool images and laser-induced plasma spectrum was built. The influences of laser power on the keyhole/molten pool morphologies and plasma thermo-mechanical characteristics were investigated. The results showed that there were significant correlations among the variations of the keyhole–molten pool, plasma spectrum, and penetration depth. The image features and spectral features were extracted by image processing and dimension-reduction methods, respectively. Moreover, several penetration depth prediction models based on single-sensor features and multi-sensor features were established. The mean square error of the neural network model built by multi-sensor features was 0.0162, which was smaller than that of the model built by single-sensor features. The established high-precision model provided a theoretical basis for real-time feedback control of the penetration depth in the laser welding process.
Experimental Study on Dynamic Characteristics of Damaged Post-Tensioning Concrete Sleepers Using Impact Hammer
Authors: Choi Jung-Youl , Shin Tae-Hyung , Kim Sun-Hee , Chung Jee-Seung
Published: March 2024

Concrete sleepers in operation are commonly damaged by various internal and external factors, such as poor materials, manufacturing defects, poor construction, environmental factors, and repeated loads and driving characteristics of trains; these factors affect the vibration response, mode shape, and natural frequency of damaged concrete sleepers. However, current standards in South Korea require only a subjective visual inspection of concrete sleepers to determine the damage degree and necessity of repair or replacement. In this study, an impact hammer test was performed on concrete sleepers installed on the operating lines of urban railroads to assess the field applicability of the modal test method, with the results indicating that the natural frequency due to concrete sleeper damage was lower than that of the undamaged state. Furthermore, the discrepancy between the simulated and measured natural frequencies of the undamaged concrete sleeper was approximately 1.87%, validating the numerical analysis result. The natural frequency of the damaged concrete sleepers was lower than that of the undamaged concrete sleeper, and cracks in both the concrete sleeper core and the rail seat had the lowest natural frequency among all the damage categories. Therefore, the damage degrees of concrete sleepers can be quantitatively estimated using measured natural-frequency values.
Degradation of Poly(ethylene terephthalate) Catalyzed by Nonmetallic Dibasic Ionic Liquids under UV Radiation
Authors: Zhang Ruiqi , Zheng Xu , Cheng Xiujie , Xu Junli , Li Yi , Zhou Qing , Xin Jiayu , Yan Dongxia , Lu Xingmei
Published: March 2024

Nonmetallic ionic liquids (ILs) exhibit unique advantages in catalyzing poly (ethylene terephthalate) (PET) glycolysis, but usually require longer reaction times. We found that exposure to UV radiation can accelerate the glycolysis reaction and significantly reduce the reaction time. In this work, we synthesized five nonmetallic dibasic ILs, and their glycolysis catalytic activity was investigated. 1,8-diazabicyclo [5,4,0] undec-7-ene imidazole ([HDBU]Im) exhibited better catalytic performance. Meanwhile, UV radiation is used as a reinforcement method to improve the PET glycolysis efficiency. Under optimal conditions (5 g PET, 20 g ethylene glycol (EG), 0.25 g [HDBU]Im, 10,000 µW·cm−2 UV radiation reacted for 90 min at 185 °C), the PET conversion and BHET yield were 100% and 88.9%, respectively. Based on the UV-visible spectrum, it was found that UV radiation can activate the C=O in PET. Hence, the incorporation of UV radiation can considerably diminish the activation energy of the reaction, shortening the reaction time of PET degradation. Finally, a possible reaction mechanism of [HDBU]Im-catalyzed PET glycolysis under UV radiation was proposed.
Synthesis of BiOX-Red Mud/Granulated Blast Furnace Slag Geopolymer Microspheres for Photocatalytic Degradation of Formaldehyde
Authors: Lu Ping , Zhang Na , Wang Ying , Wang Yidi , Zhang Jiale , Cai Qingyi , Zhang Yihe
Published: March 2024

Release of formaldehyde gas indoors is a serious threat to human health. The traditional adsorption method is not stable enough for formaldehyde removal. Photocatalytic degradation of formaldehyde is effective and rapid, but photocatalysts are generally expensive and not easy to recycle. In this paper, geopolymer microspheres were applied as matrix materials for photocatalysts loading to degrade formaldehyde. Geopolymer microspheres were prepared from red mud and granulated blast furnace slag as raw materials by alkali activation. When the red mud doping was 50%, the concentration of NaOH solution was 6 mol/L, and the additive amount was 30 mL, the prepared geopolymer microspheres possessed good morphological characteristics and a large specific surface area of 38.80 m2/g. With the loading of BiOX (X = Cl, Br, I) photocatalysts on the surface of geopolymer microspheres, 85.71% of formaldehyde gas were adsorbed within 60 min. The formaldehyde degradation rate of the geopolymer microspheres loaded with BiOI reached 87.46% within 180 min, which was 23.07% higher than that of the microspheres loaded with BiOBr, and 50.50% higher than that of the microspheres loaded with BiOCl. While ensuring the efficient degradation of formaldehyde, the BiOX (X = Cl, Br, I)-loaded geopolymer microspheres are easy to recycle and can save space. This work not only promotes the resource utilization of red mud and granulated blast furnace slag, but also provides a new idea on the formation of catalysts in the process of photocatalytic degradation of formaldehyde.
Numerical Study on Electromagnetic Hydraulic Forming Process to Overcome Limitations of Electromagnetic Forming Process
Authors: Kim Yeon-Bok , Kim Jeong
Published: March 2024

This paper provides a comparison between the conventional Electromagnetic Forming (EMF) technique and the novel Electromagnetic Hydraulic Forming (EMHF) approach. The EMHF involves the use of finite element analysis coupled with the EM and arbitrary Lagrangian–Eulerian techniques analyzed through LS-DYNA. In the free-bulge configuration, EMF is influenced by the forming coil, resulting in a dead zone and uneven forming. Additionally, EMF can only be used to shape materials with high electrical conductivity. In contrast, EMHF, driven by induced hydraulic pressure from the electromagnetic field-affected drive sheet, is independent of the electrical conductivity of the material and produces dome-shaped workpieces. For rectangular die shapes, EMF is prone to collision owing to the acceleration of the blank, which results in a reduced quality owing to bouncing. However, EMHF exhibits no bouncing effect and successfully achieves the target shape in most cases. The two techniques differ in the strain rate, with EMF at 4850/s, whereas EMHF operates at approximately 1250/s. Despite being slower, EMHF is still a high-speed forming technique. In conclusion, EMHF is a promising technique capable of addressing the shortcomings of conventional EMF and achieving improvements in forming processes.
Three-Dimensional Epitaxy of Low-Defect 3C-SiC on a Geometrically Modified Silicon Substrate
Authors: Colston Gerard , Turner Kelly , Renz Arne , Perera Kushani , Gammon Peter M. , Antoniou Marina , Shah Vishal A.
Published: March 2024

We demonstrate the growth of 3C-SiC with reduced planar defects on a micro-scale compliant substrate. Heteroepitaxial growth of 3C-SiC on trenches with a width and separation of 2 µm, etched into a Si(001) substrate, is found to suppress defect propagation through the epilayer. Stacking faults and other planar defects are channeled away from the center of the patterned structures, which are rounded through the use of H2 annealing at 1100 °C. Void formation between the columns of 3C-SiC growth acts as a termination point for defects, and coalescence of these columns into a continuous epilayer is promoted through the addition of HCl in the growth phase. The process of fabricating these compliant substrates utilizes standard processing techniques found within the semiconductor industry and is independent of the substrate orientation and offcut.
Development of an EN8 Steel Stepped Rotor by a Novel Engraving Milling Technique
Authors: Chaubey Sujeet Kumar , Gupta Kapil
Published: March 2024

The rotor or impeller is a rotational and key part of a pump and compressor. This article presents the detailed development process of a rotor of small size constructed from an EN8 steel cylindrical blank using a novel technique based on a computer numerical control engraving milling machine (CNC-EMM) equipped with a 4 mm tungsten carbide end mill cutter. We fabricated a total of twenty-eight stepped rotors following the Box–Behnken Design (BBD) DoE technique at fourteen distinct combinations of CNC-EMM variable parameters, namely rotational speed, feed, and plunge feed. Average roughness ‘Ra’, an important surface quality indicator, has been considered and presented in this article, as a quality measure for the fabricated rotors. Feed and plunge feed have been identified as the most influencing variable parameters as per an analysis of variance (ANOVA) test. The lowest average roughness value obtained by this process for the rotor blade was 0.11 µm. A micrograph obtained from a field-emission scanning electron microscope (FE-SEM) showed a uniform and accurate tooth profile along with burr formation at corner edges. This study claims to establish engraving milling as a viable alternative to other manufacturing processes used for rotor blades. The findings of this study are useful to scholars, engineers, and researchers who are exploring new ways to fabricate mechanical parts and components.
Enhancing the Longitudinal Compressive Strength of Freeform 3D-Printed Continuous Carbon Fiber-Reinforced Polymer Composite Laminate Using Magnetic Compaction Force and Nanofiber Z-Threads
Authors: Islam Mohammad Rakibul , Uddin Md Nazim , Taylor Wyatt , Warren Ryan , Hsiao Kuang-Ting
Published: March 2024

Low fiber-direction compressive strength is a well-recognized weakness of carbon fiber-reinforced polymer (CFRP) composites. When a CFRP is produced using 3D printing, the compressive strength is further degraded. To solve this issue, in this paper, a novel magnetic compaction force-assisted additive manufacturing (MCFA-AM) method is used to print CFRP laminates reinforced with carbon nanofiber (CNF) z-threads (i.e., ZT-CFRP). MCFA-AM utilizes a magnetic force to simultaneously levitate, deposit, and compact fast-curing CFRP prepregs in free space and quickly solidifies the CFRP laminate part without any mold nor supporting substrate plate; it effectively reduces the voids. The longitudinal compressive test was performed on five different sample types. ZT-CFRP/MCFA-AM samples were printed under two different magnetic compaction rolling pressures, i.e., 0.5 bar and 0.78 bar. Compared with the longitudinal compressive strength of a typical CFRP manufactured by the traditional out-of-autoclave–vacuum-bag-only (OOA-VBO) molding process at the steady-state pressure of 0.82 bar, the ZT-CFRP/MCFA-AM samples showed either comparable results (by −1.00% difference) or enhanced results (+7.42% improvement) by using 0.5 bar or 0.78 bar magnetic rolling pressures, respectively.
A Broadband Photodetector Based on Non-Layered MnS/WSe2 Type-I Heterojunctions with Ultrahigh Photoresponsivity and Fast Photoresponse
Authors: Xie Chaojie , Yang Yibin , Li Kunle , Cao Xuanhao , Chen Shanshan , Zhao Yu
Published: March 2024

The separation of photogenerated electron–hole pairs is crucial for the construction of high-performance and wide-band responsive photodetectors. The type-I heterojunction as a photodetector is seldomly studied due to its limited separation of the carriers and narrow optical response. In this work, we demonstrated that the high performance of type-I heterojunction as a broadband photodetector can be obtained by rational design of the band alignment and proper modulation from external electric field. The heterojunction device is fabricated by vertical stacking of non-layered MnS and WSe2 flakes. Its type-I band structure is confirmed by the first-principles calculations. The MnS/WSe2 heterojunction presents a wide optical detecting range spanning from 365 nm to 1550 nm. It exhibits the characteristics of bidirectional transportation, a current on/off ratio over 103, and an excellent photoresponsivity of 108 A W−1 in the visible range. Furthermore, the response time of the device is 19 ms (rise time) and 10 ms (fall time), which is much faster than that of its constituents MnS and WSe2. The facilitation of carrier accumulation caused by the interfacial band bending is thought to be critical to the photoresponse performance of the heterojunction. In addition, the device can operate in self-powered mode, indicating a photovoltaic effect.
Evaluation of Phenobarbital Adsorption Efficiency on Biosorbents or Activated Carbon Obtained from Adansonia Digitata Shells
Authors: Ndankou Charnella Stevine Dibandjo , Ștefan Daniela Simina , Nsami Ndi Julius , Daouda Kouotou , Bosomoiu Magdalena
Published: March 2024

The removal of pharmaceutically active compounds present in relatively low concentration in wastewater is critical. This is because they have a severe, negative impact on life and the environment. To address this issue, adsorption was used, which is an effective wastewater treatment method for removing substances found in low concentrations in water. This study compared the adsorption performance of active carbon to three biosorbents derived from Adansonia digitata shells. The adsorbents were prepared and characterized using TGA, SEM, EDX, and FTIR analyses and pHPZC. To better understand the adsorption process, equilibrium and reaction kinetics studies were conducted. The effect of contact time, initial phenobarbital concentration, adsorbent mass, and pH was investigated in static conditions. The adsorption results revealed that the biosorbent B3 has a higher affinity for the eliminated compound, with an equilibrium time of 60 min and an adsorption capacity of 47.08 mg/g at an initial concentration of 50 mg/L. The experimental data are consistent with Langmuir and Sips adsorption isotherm models, and with the pseudo-second order and Elovich models for kinetics description. This indicates strong interactions between the adsorbent materials and the pharmaceutical micropollutant. Based on these findings, it appears that, among the tested materials, B3 biosorbent is the most efficient for removing phenobarbital present in low concentrations in water.
The Influence of Solar Ageing on the Compositions of Epoxy Resin with Natural Polyphenol Quercetin
Authors: Latos-Brozio Malgorzata , Czechowski Leszek , Masek Anna
Published: March 2024

Epoxy resin compositions are used in modern railways, replacing other materials. However, epoxy composites in public transport are subject to many requirements, including that they should be flame retardant and resistant to weather conditions. The aim of the research was to analyse the resistance to solar ageing of epoxy resin composites containing flame retardants and the addition of the natural stabilising substance—quercetin. The homogeneity of the samples (optical microscopy and FTIR spectroscopy) and their thermal stability (TGA thermogravimetry) were analysed. The T5 temperature, which is the initial temperature of thermal decomposition of the samples, was 7 °C higher for the epoxy resin containing quercetin, so the material with polyphenol was characterised by better thermal resistance. Changes in material properties (hardness, surface energy, carbonyl index, colour) after 800 h solar ageing were investigated. The tensile tests on materials were executed for three different directions before and after ageing effect. The samples showed good resistance to degradation factors, i.e., they retained the functional properties (hardness and mechanical properties). However, analysis of carbonyl indices and surface energies showed that changes appeared in the composites after solar ageing, suggesting the beginning of material degradation. An approximately 3-fold increase in the polar component in epoxy resin compositions (from approximately 3 mN/m to approximately 11 mN/m) is associated with an increase in their hydrophilicity and the progress of ageing of the materials’ surface. The obtained results are an introduction to further research on the long-term degradation processes of epoxy resins with plant stabilisers.
Application of a Carbon Fiber Microelectrode as a Sensor for Apocynin Electroanalysis
Authors: Michalkiewicz Slawomir , Skorupa Agata , Jakubczyk Magdalena , Bębacz Karolina
Published: March 2024

In this study, a carbon fiber microelectrode (CF) was applied for the investigation of the electrochemical behavior of the natural antioxidant, apocynin (APO). Given the limited solubility of APO in water, a mixture of anhydrous acetic acid (AcH) with 20%, v/v acetonitrile (AN) and 0.1 mol L−1 sodium acetate (AcNa) was used. The electrochemical properties of APO were examined through linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), and cyclic voltammetry (CV). The anodic oxidation of APO, which is the basis of the method used, proved to be diffusion-controlled and proceeded with a two-electron and one proton exchange. Both radicals and radical cations, arising from the first and second step of electrode reactions, respectively, underwent subsequent chemical transformations to yield more stable final products (EqCiEiCi mechanism). Using optimized DPV conditions, the anodic peak current of APO at a potential of 0.925 V vs. Ag/AgCl showed a good linear response within the concentration range of 2.7 × 10−6–2.6 × 10−4 mol L−1. The detection and quantification limits were determined as 8.9 × 10−7 and 2.7 × 10−6 mol L−1, respectively. The developed DPV method enabled the successful determination of APO in herbal extracts and in dietary supplements. It should be noted that this is the first method to be used for voltammetric determination of APO.
Towards Understanding {10-11}-{10-12} Secondary Twinning Behaviors in AZ31 Magnesium Alloy during Fatigue Deformation
Authors: You Yunxiang , Tan Li , Yan Yuqin , Zhou Tao , Yang Pengfei , Tu Jian , Zhou Zhiming
Published: March 2024

Tensile-compression fatigue deformation tests were conducted on AZ31 magnesium alloy at room temperature. Electron backscatter diffraction (EBSD) scanning electron microscopy was used to scan the microstructure near the fatigue fracture surface. It was found that lamellar {10-11}-{10-12} secondary twins (STs) appeared inside primary {10-11} contraction twins (CTs), with a morphology similar to the previously discovered {10-12}-{10-12} STs. However, through detailed misorientation calibration, it was determined that this type of secondary twin is {10-11}-{10-12} ST. Through calculation and analysis, it was found that the matrix was under compressive stress in the normal direction (ND) during fatigue deformation, which was beneficial for the activation of primary {10-11} CTs. The local strain accommodation was evaluated based on the geometric compatibility parameter (m’) combined with the Schmid factor (SF) of the slip system, leading us to propose and discuss the possible formation mechanism of this secondary twin. The analysis results indicate that when the local strain caused by basal slip at the twin boundaries cannot be well transmitted, {10-11}-{10-12} STs are activated to coordinate the strain, and different loading directions lead to different formation mechanisms. Moreover, from the microstructure characterization near the entire fracture surface, we surmise that the presence of such secondary twins is not common.