bluuebunny/crossref_metadata_2025 huggingface dataset:
The Anisotropic Mechanical and Tribological Behaviors of Additively Manufactured (Material Extrusion) Implant-Grade Polyether Ether Ketone (PEEK)
Authors: Maydanshahi Mohammad Reza , Najari Mohammad Reza , Slatter Tom , Mohammadpour Mahdi
Published: October 2024

In this study, we investigated the mechanical and tribological properties of the layer-by-layer structure of additively manufactured implant-grade Polyether Ether Ketone (PEEK) through the Material Extrusion (ME) process as a potential substitute for artificial joints. The effective elasticity modulus of the anisotropic 3D-printed PEEK was determined to be 2.505 GPa along the vertical and horizontal build orientations. The lubricated friction and wear performance were assessed using a pin-on-disk test under various loads, including 14, 30, 50, and 70 N, with a sliding speed of 50 mm/s over a total distance of 1 km at 37 °C. The contact parameters between the hemispherical steel pin and 3D-printed PEEK disks, involving contact pressures over the circle of contact, were observed to increase as the load increased. The results indicated that the wear coefficient exhibited a rise from 1.418 × 10−5 to 2.089 × 10−1  as the applied loads increased, signaling a shift from mild to severe wear regimes. Fetal Bovine Serum (FBS) as a lubricant exhibited a mixed mechanism, ascertained through the Stribeck curve, as well as a minimum fluid film thickness of 1.346 nm under an isoviscous–elastic regime, as calculated by the maximum load. Moreover, the mechanism governing wear during sliding, influenced by both normal axial and shear loads, primarily involved adhesion.
Effects of Structure Parameters on Static Performance of Gas Foil Bearings Based on a New Fully Coupled Elastic–Aerodynamic Model
Authors: Ding Pengjing , Hu Yang , Wang Xiaojing , Meng Yonggang
Published: October 2024

Accurately predicting the performance of gas foil bearings (GFBs) is important. This paper presents a new fully coupled elastic–aerodynamic model for analyzing the static performance of gas foil journal bearings (GFJBs). The gas compressible lubrication model was solved in MATLAB to obtain the gas pressure. The foil structure deformation was solved in COMSOL by considering the Coulomb friction and allowing the contact surfaces to be separated from each other. Under given load and rotational speed conditions, the calculated minimum gas film thickness and attitude angle match well with the literature data, validating the accuracy of the developed model. Based on the model developed, a comprehensive and systematic analysis of the effects of the structural parameters on the static performance was performed. The results showed that as the bump height, top foil thickness, and bump foil thickness increased, the load capacity could be improved to different degrees. The bump foil thickness had the greatest effect on the load capacity. These results provide theoretical guidance for the structural design and practical applications of GFJBs.
Research Progress on Current-Carrying Friction with High Stability and Excellent Tribological Behavior
Authors: Wei Peng , Wang Xueqiang , Jing Guiru , Li Fei , Bai Pengpeng , Tian Yu
Published: October 2024

Current-carrying friction affects electrical contact systems like switches, motors, and slip rings, which determines their performance and lifespan. Researchers have found that current-carrying friction is influenced by various factors, including material type, contact form, and operating environment. This article first reviews commonly used materials, such as graphite, copper, silver, gold, and their composites. Then different contact forms like reciprocating, rotational, sliding, rolling, vibration, and their composite contact form are also summarized. Finally, their environmental conditions are also analyzed, such as air, vacuum, and humidity, on frictional force and contact resistance. Additionally, through experimental testing and theoretical analysis, it is found that factors such as arcing, thermal effects, material properties, contact pressure, and lubrication significantly influence current-carrying friction. The key mechanisms of current-carrying friction are revealed under different current conditions, including no current, low current, and high current, thereby highlighting the roles of frictional force, material migration, and electroerosion. The findings suggest that material selection, surface treatment, and lubrication techniques are effective in enhancing current-carrying friction performance. Future research should focus on developing new materials, intelligent lubrication systems, stronger adaptability in extreme environments, and low friction at the microscale. Moreover, exploring stability and durability in extreme environments and further refining theoretical models are essential to providing a scientific basis for designing efficient and long-lasting current-carrying friction systems.
Review of Wear and Mechanical Characteristics of Al-Si Alloy Matrix Composites Reinforced with Natural Minerals
Authors: Singhal Varun , Shelly Daksh , Babbar Atul , Lee Seul-Yi , Park Soo-Jin
Published: October 2024

Al-Si alloys are vital in the aerospace and automotive industries due to their high strength-to-weight ratio, excellent ductility, and superior corrosion resistance. These properties, along with good thermal conductivity, low thermal expansion, and enhanced wear resistance due to silicon, make them ideal for lightweight, high-performance components like engine parts exposed to harsh conditions and thermal cycling. In recent years, the development of aluminium metal matrix composites using Al-Si alloys as the base material has gathered significant attention. These composites are engineered by integrating various reinforcing particles into the aluminium matrix, which results in remarkable improvements in the wear resistance, hardness, and overall mechanical performance of the material. The stir casting process, a well-established and cost-effective method, is frequently employed to ensure a uniform distribution of these reinforcing particles within the matrix. This review delves into the influence of different types of reinforcing particles on the properties of Al-Si alloy-based AMCs. The incorporation of these reinforcements has been shown to significantly enhance wear resistance, reduce friction, and improve the overall strength and toughness of the composites, making them ideal candidates for high-performance applications in the automotive and aerospace sectors. Moreover, this review highlights the challenges associated with the fabrication of these composites, such as achieving a homogeneous particle distribution and minimizing porosity. It also discusses the latest advancements in processing techniques aimed at overcoming these challenges. Additionally, this review addresses the potential environmental and economic benefits of using natural reinforcements, which not only reduce material costs but also contribute to sustainable manufacturing practices.
Predictive Model for Scuffing Temperature Field Rise of Spiral Bevel Gears under Different Machining Conditions
Authors: Cai Zhi-Jie , Zheng Xi-Qing , Lan Hui-Qing , Wang Liu-Na , Yang Si-Wei , Shen Rui
Published: October 2024

Spiral bevel gears are extensively employed in mechanical transmissions; however, they are prone to adhesive wear when operating under high-speed and heavy-load conditions. Research indicates that the tooth surface roughness of gears significantly influences the friction and wear of the meshing gears. The present study delves into the origins of tooth surface roughness through the integration of the W-M function and fractal theory. Utilizing an involute helical gear with surface roughness for tooth cutting, a three-dimensional model is established with roughened tooth surfaces. This paper introduces an approach to developing three-dimensional gear models with roughness and applies the finite element method to perform thermodynamic analysis on gears exhibiting diverse levels of surface roughness. The thermal analysis of gears with varying degrees of roughness was conducted using the finite element method. Comparative analysis of the results under specific operating conditions elucidated the impact of roughness on tooth surface temperature rise. In order to validate the simulation model, an experimental test platform for spiral bevel gears of identical size was established. This model integrates tooth surface roughness with thermodynamic analysis, allowing for the rapid assessment of tooth surface temperature rise under different machining conditions, and reducing the cost of validating predicted tooth surface load-carrying capacity.
Durability Investigation of Ultra-Thin Polyurethane Wearing Course for Asphalt Pavement
Authors: Wang Wenguang , Liu Baodong , Jin Dongzhao , Yu Miao , Zeng Junsen
Published: October 2024

In this study, a wear-resistant ultra-thin wear layer was fabricated with polyurethane as an adhesive to investigate its durability for pavement applications. Its road performance was investigated based on indoor tests. First, the abrasion test was performed using a tire–pavement dynamic friction analyzer (TDFA), and the surface elevation information of the wear layer was obtained by laser profile scanning. The relationship between the anti-skid properties of the wear layer and the macro-texture was analyzed. Second, a Fourier infrared spectrometer and scanning electron microscope were employed to analyze the evolution of polyurethane aging properties in the pull-out test and accelerated ultraviolet (UV) aging test. The results showed that the mean profile depth (MPD), arithmetic mean wavelength of contour (λa), surface wear index (SBI), stage mass loss rate (σ), and total stage mass loss rate (ω) of the abrasive layer aggregate had significant multivariate quadratic polynomial relationships with the skidding performance of the abrasive layer. The tensile strength of the polyurethane ultra-thin abrasive layer decreased by only 2.59% after 16 days of UV aging, indicating a minimal effect of UV action on the aggregate and structural spalling of the polyurethane abrasive layer.
Enhancing Magnesium Bioactivity for Biomedical Applications: Effects of Laser Texturing and Sandblasting on Surface Properties
Authors: Conradi Marjetka , Kocijan Aleksandra , Podgornik Bojan
Published: October 2024

Magnesium and its alloys, valued for their lightweight and durable characteristics, have garnered increasing attention for biomedical applications due to their exceptional biocompatibility and biodegradability. This work introduces a comparison of advanced and basic methods—laser texturing and sandblasting—on magnesium surfaces to enhance bioactivity for biomedical applications. Employing a comprehensive analysis spanning surface morphology, hardness, wettability, tribological performance, and corrosion behavior, this study elucidates the intricate relationship between varied surface treatments and magnesium’s performance. Findings reveal that both laser texturing and sandblasting induce grain refinement. Notably, sandblasting, particularly with a duration of 2 s, demonstrates superior wear resistance and reduced corrosion rates compared to untreated magnesium, thereby emerging as a promising approach for enhancing magnesium bioactivity in biomedical contexts. This investigation contributes to a deeper understanding of the nuanced interactions between diverse surface treatments and their implications for magnesium implants in chloride-rich environments, offering valuable insights for prospective biomedical applications.
SLM Magnesium Alloy Micro-Arc Oxidation Coating
Authors: Yue Xuejie , Xu Kangning , Wang Shuyi , Liu Hengyan , Guo Shiyue , Zhao Rusheng , Xu Gaopeng , Wang Hao , Yue Xuezheng
Published: October 2024

In this study, we utilized Selective Laser Melting (SLM) technology to fabricate a magnesium alloy, and subsequently subject it to micro-arc oxidation treatment. We analyzed and compared the microstructure, elemental distribution, wetting angle, and corrosion resistance of the SLM magnesium alloy both before and after the micro-arc oxidation process. The findings indicate that the SLM magnesium alloy exhibits surface porosity defects ranging from 2% to 3.2%, which significantly influence the morphology and functionality of the resulting film layer formed during the micro-arc oxidation process. These defects manifest as pores on the surface, leading to an uneven distribution of micropores with varying sizes across the layer. The surface roughness of the 3D-printed magnesium alloy exhibits a high roughness value of 180 nanometers. The phosphorus (P) content is lower within the film layer compared to the surface, suggesting that the Mg3(PO4)2 phase predominantly resides on the surface, whereas the interior is primarily composed of MgO. The micro-arc oxidation process enhances the hydrophilicity and corrosion resistance of the SLM magnesium alloy, thereby potentially endowing it with bioactivity. Additionally, the increased surface roughness post-treatment promotes cell proliferation. However, certain inherent defects present in the SLM magnesium alloy samples negatively impact the improvement of their corrosion resistance.
Laser Powder Bed Fusion Parameters Optimization for Enhanced Mechanical Properties of EOS Co-Cr Dental Alloy
Authors: Viderščak Dalibor , Schauperl Zdravko , Runje Biserka , Šolić Sanja , Ćatić Amir , Godec Matjaž , Paulin Irena , Donik Črtomir
Published: October 2024

This research explores how variations in laser powder bed fusion (LPBF) parameters—laser power (P), scanning speed (v), and base plate preheating temperature (ϑp)—affect the mechanical properties of the EOS Co-Cr SP2 dental alloy. A central composite design (CCD) was used to optimize the process parameters. Mechanical testing focused on crucial properties for dental applications, including yield strength (Rp0.2), elongation (ε), toughness (KVa), and flexural strength (Rms). Microstructural analysis was conducted using light and electron microscopy, while XRD identified microstructural phases. Statistical analysis (ANOVA, Scheffé post hoc test, α = 0.05) revealed significant effects of P, v, and ϑp on the mechanical properties. Response surface models (RSMs) were developed, and optimal parameters were determined to achieve maximum toughness and flexural strength. Maximum values were obtained with laser power above 205 W and base plate preheating at 310 °C. The mathematical model predicted toughness values with less than 5% deviation from experimental results, indicating high accuracy.
Performance Evaluation of Pebble Concrete for Pavement: A Study on the Sucre Highway Project
Authors: Feng Zhuqing , Lu Jue , Liu Simin , Xia Jingliang , Wang Jing , Leng Faguang , Ma Xinxin
Published: October 2024

Bolivia has abundant pebbles, while the supply of crushed stone is limited and unstable. Thus, the resource utilization of local pebble as a coarse aggregate and the guarantee of concrete durability are the key scientific issues in the Sucre Highway Project. In this paper, a comparative analysis was conducted of the performance of crushed stone concrete and pebble concrete. Additionally, the impact of fly ash on the water permeability resistance of concrete was investigated. The results indicate that the apparent density, bulk density, and void ratio of pebbles are lower than those of crushed stone, and the aggregate gradation of pebbles is dispersed. The type of aggregate is the primary factor influencing the splitting tensile strength of concrete, with the main failure modes of pebble concrete being slurry cracking, aggregate crushing, and interface debonding. While aggregate and fly ash have a minor effect on compressive strength, they significantly impact flexural tensile strength; however, all concretes meet the requirements for extra-heavy, very heavy, and heavy traffic load levels. In terms of impermeability, fly ash effectively mitigates the negative impact of aggregate type on the impermeability of concrete. These findings support the application of pebble concrete in the highway project.
Graphite–Phosphate Composites: Structure and Voltammetric Investigations
Authors: Rada Simona , Gorea Alexandra Barbu , Culea Eugen
Published: October 2024

The utilization of lithium-ion batteries (LIBs) is increasing sharply with the increasing use of mobile phones, laptops, tablets, and electric vehicles worldwide. Technologies are required for the recycling and recovery of spent LIBs. In the context of the circular economy, it is urgent to search for new methods to recycle waste graphite that comes from the retired electrode of LIBs. The conversion of waste graphite into other products, such as new electrodes, in the field of energy devices is attractive because it reduces resource waste and processing costs, as well as preventing environmental pollution. In this paper, new electrode materials were prepared using waste anode graphite originating from a spent mobile phone battery with an xBT·0.1C12H22O11·(0.9-x)(NH4)2HPO4 composition, where x = 0–50 weight% BT from the anodic active mass of the spent phone battery (labeled as BT), using the melt quenching method. Analysis of the diffractograms shows the graphite crystalline phase with a hexagonal structure in all prepared samples. The particle sizes decrease by adding a higher BT amount in the composites. The average band gap is 1.32 eV (±0.3 eV). A higher disorder degree in the host network is the main factor responsible for lower band gap values. The prepared composites were tested as electrodes in an LIB or a fuel cell, achieving an excellent electrochemical performance. The voltammetric studies indicate that doping with 50% BT is the most suitable for applications as electrodes in LIBs and fuel cells.
The Evolution of Dilatant Shear Bands in High-Pressure Die Casting for Al-Si Alloys
Authors: Lu Jingzhou , Lordan Ewan , Zhang Yijie , Fan Zhongyun , Wang Wanlin , Dou Kun
Published: October 2024

Bands of interdendritic porosity and positive macrosegregation are commonly observed in pressure die castings, with previous studies demonstrating their close relation to dilatant shear bands in granular materials. Despite recent technological developments, the micromechanism governing dilatancy in the high-pressure die casting (HPDC) process for alloys between liquid and solid temperature regions is still not fully understood. To investigate the influence of fluid flow and the size of externally solidified crystals (ESCs) on the evolution of dilatant shear bands in HPDC, various filling velocities were trialled to produce HPDC samples of Al8SiMnMg alloys. This study demonstrates that crystal fragmentation is accompanied by a decrease in dilatational concentration, producing an indistinct shear band. Once crystal fragmentation stagnates, the enhanced deformation rate associated with a further increase in filling velocity (from 2.2 ms−1 to 4.6 ms−1) localizes dilatancy into a highly concentrated shear band. The optimal piston velocity is 3.6 ms−1, under which the average ESC size reaches the minimum, and the average yield stress and overall product of strength and elongation reach the maximum values of 144.6 MPa and 3.664 GPa%, respectively. By adopting the concept of force chain buckling in granular media, the evolution of dilatant shear bands in equiaxed solidifying alloys can be adequately explained based on further verification with DEM-type modeling in OpenFOAM. Three mechanisms for ESC-enhanced dilation are presented, elucidating previous reports relating the presence of ESCs to the subsequent shear band characteristics. By applying the physics of granular materials to equiaxed solidifying alloys, unique opportunities are presented for process optimization and microstructural modeling in HPDC.
Linear and Volumetric Polyethylene Wear Patterns after Primary Cruciate-Retaining Total Knee Arthroplasty Failure: An Analysis Using Optical Scanning and Computer-Aided Design Models
Authors: Valič Matej , Milošev Ingrid , Levašič Vesna , Blas Mateja , Podovšovnik Eva , Koren Jaka , Trebše Rihard
Published: October 2024

(1) Background: Analyses of retrieved inserts allow for a better understanding of TKA failure mechanisms and the detection of factors that cause increased wear. The purpose of this implant retrieval study was to identify whether insert volumetric wear significantly differs among groups of common causes of total knee arthroplasty failure, whether there is a characteristic wear distribution pattern for a common cause of failure, and whether nominal insert size and component size ratio (femur-to-insert) influence linear and volumetric wear rates. (2) Methods: We digitally reconstructed 59 retrieved single-model cruciate-retaining inserts and computed their articular load-bearing surface wear utilizing an optical scanner and computer-aided design models as references. After comprehensively reviewing all cases, each was categorized into one or more of the following groups: prosthetic joint infection, osteolysis, clinical loosening of the component, joint malalignment or component malposition, instability, and other isolated causes. The associations between volumetric wear and causes of failure were estimated using a multiple linear regression model adjusted for time in situ. Insert linear penetration wear maps from the respective groups of failure were further processed and merged to create a single average binary image, highlighting a potential wear distribution pattern. The differences in wear rates according to nominal insert size (small vs. medium vs. large) and component size ratio (≤1 vs. >1) were tested using the Kruskal–Wallis test and the Mann–Whitney test, respectively. (3) Results: Patients with identified osteolysis alone and those also with clinical loosening of the component had significantly higher volumetric wear when compared to those without both causes (p = 0.016 and p = 0.009, respectively). All other causes were not significantly associated with volumetric wear. The instability group differentiated from the others with a combined peripheral antero-posterior wear distribution. Linear and volumetric wear rates showed no significant differences when compared by nominal insert size (small vs. medium vs. large, p = 0.563 and p = 0.747, respectively) or by component (femoral-to-insert) size ratio (≤1 vs. >1, p = 0.885 and p = 0.055, respectively). (4) Conclusions: The study found increased volumetric wear in cases of osteolysis alone, with greater wear when combined with clinical loosening compared to other groups. The instability group demonstrated a characteristic peripheral anterior and posterior wear pattern. Insert size and component size ratio seem not to influence wear rates.
A Systematic Review of AI-Driven Prediction of Fabric Properties and Handfeel
Authors: Tu Yi-Fan , Kwan Mei-Ying , Yick Kit-Lun
Published: October 2024

Artificial intelligence (AI) is revolutionizing the textile industry by improving the prediction of fabric properties and handfeel, which are essential for assessing textile quality and performance. However, the practical application and translation of AI-predicted results into real-world textile production remain unclear, posing challenges for widespread adoption. This paper systematically reviews AI-driven techniques for predicting these characteristics by focusing on model mechanisms, dataset diversity, and prediction accuracy. Among 899 papers initially identified, 39 were selected for in-depth analysis through both bibliometric and content analysis. The review categorizes and evaluates various AI approaches, including machine learning, deep learning, and hybrid models, across different types of fabric. Despite significant advances, challenges remain, such as ensuring model generalization and managing complex fabric behavior. Future research should focus on developing more robust models, integrating sustainability, and refining feature extraction techniques. This review highlights the critical gaps in the literature and provides practical insights to enhance AI-driven prediction of fabric properties, thus guiding future textile innovations.
Leveraging Bayesian Optimization Software for Atomic Layer Deposition: Single-Objective Optimization of TiO2 Layers
Authors: Häussermann Philipp , Joseph Nikhil Biju , Hiller Daniel
Published: October 2024

We demonstrate the application of free-to-use and easy-to-implement Bayesian optimization (BO) software to streamline atomic layer deposition (ALD) process optimization. By employing machine learning-based Bayesian optimization algorithms, we enhanced the silicon surface passivation quality of titanium dioxide layers deposited using titanium tetraisopropoxide (TTIP). Unlike classical designs of experimental methods, such as Box–Behnken or Plackett–Burman designs, which require a predefined set of experiments and can become resource intensive, BO offers several advantages. It dynamically updates the search strategy based on previous outcomes, allowing for efficient exploration of parameter spaces with fewer experimental runs. This adaptive approach is particularly advantageous in small-scale experiments or laboratories where time, resources, and materials are limited. In a single-objective optimization experiment, we identified constrained search spaces that limited further optimization, underscoring the importance of properly defined parameter bounds prior to the optimization process. Our findings highlight that Bayesian optimization can not only reduce time and resource costs associated with ALD process optimization but also support faster discovery of more optimal ALD process parameters, even with minimal prior knowledge of the deposition process or precursor chemistry.
Carbon Sequestration by Preparing Recycled Cement, Recycled Aggregates, and Recycled Concrete from Construction and Demolition (C&D) Wastes
Authors: Luo Jing , Huang Rong , Wang Junjie , Zhang Yi
Published: October 2024

As the world’s largest producer of construction waste, China’s recycling and related policies are of the biggest concern to the world. However, the effective disposal and reuse of this waste has become an important issue since currently China still has a very low recycling ratio compared to developed countries, and most of the waste concrete was only simply broken and used as low-grade recycled aggregates for subgrade cushion, cement stabilized crushed stone, and filler wall. In this paper, a concrete cycle model focusing on how to effectively recycle and utilize waste concrete is put forward to prepare high quality recycled concrete, especially through a series of technical means, such as effective separation, carbon sequestration, and reactivation. Producing high quality recycled concrete can not only replace traditional concrete but also effectively reduce the consumption and waste of raw materials. What’s more, the calculation results show a potential of significantly carbon sink; for every ton of recycled cement produced, the CO2 emission could be reduced by 0.35–0.77 tons compared to ordinary Portland cement, corresponding to a reduction of 47%–94%; and for every ton of recycled concrete produced, the CO2 emission could be reduced by 0.186 tons compared to normal concrete. A yearly CO2 sequestration of 1.4–3.08 gigatonnes could happen if the ordinary Portland cement could be replaced by the recycled cement around the world. Taking the currently accumulated construction and demolition (C&D) wastes globally, the production of recycled cement, recycled aggregates, and recycled concrete could induce a significant carbon sink in the world.
Reset-Voltage Controlled Resistance-State and Applications of Forming-Free Fe-Doped SrTiO3 Thin-Film Memristor
Authors: Lee Ke-Jing , Wu Cheng-Hua , Lee Cheng-Jung , Chou Dei-Wei , Wang Na-Fu , Wang Yeong-Her
Published: October 2024

In this study, we prepared a strontium ferrite titanate (STF) thin film using a sol–gel process to insulate resistive random-access memory (RRAM) applications. Compared to the typical strontium titanate (STO) RRAM, the improvement in the resistive switching characteristics in STF RRAM is obvious. The Al/STO/ITO/Glass RRAM set/reset voltages of −1.4 V/+3.3 V and the Al/STF/ITO/Glass RRAM set/reset voltages of −0.45 V/+1.55 V presented a memory window larger than 103, a low operating voltage and device stability of more than 104 s. In this study, the influence of Fe on the conducting paths and the bipolar resistive switching properties of Al/STF/ITO/Glass RRAM devices is investigated.
Development and Characterization of Lime-Based Mortars Modified with Graphene Nanoplatelets
Authors: Pivák Adam , Pavlíková Milena , Záleská Martina , Pavlík Zbyšek
Published: October 2024

Materials for the conservation of cultural heritage must meet specific demands, such as high durability, service life, and compatibility with other materials used in the original building structures. Due to their low permeability to water and water vapor and their high rigidity, the use of Portland cement (PC) mortars, despite their high mechanical resistance and durability, does not represent an appropriate solution for the repair of historic masonry and structures. Their incompatibility with the original materials used in the past, often on a lime basis, is therefore a serious deficiency for their application. On the other hand, lime-based mortars, compared to PC-based materials, are more susceptible to mechanical stress, but they possess high porosity, a high water vapor transmission rate, and moderate liquid water transport. This study aims at the development of two types of lime-based mortars, calcium lime (CL) and hydraulic lime (HL). The modification of mortars was conducted with a carbon-based nanoadditive and graphene nanoplatelets (GNs) in three dosages: 0.1%, 0.3%, and 0.5% of the binder weight. The enhancement of CL mortars by GNs greatly increased mechanical strength and affected heat transport characteristics, while other characteristics such as porosity, water absorption, and drying rate remained almost similar. The application of GNs to HL not only enhanced the strength of mortars but also decreased their porosity, influenced pore size distribution, and other dependent characteristics. It can be concluded that the use of graphene nanoplatelets as an additive of lime-based composites can be considered a promising method to reinforce and functionalize these composite materials. The improved mechanical resistance while maintaining other properties may be favorable in view of the increasing requirements of building materials and may prolong the life span of building constructions.
Regression Analysis and Optimum Values of Austempering Affecting Mechanical Properties of Compacted Graphite Iron
Authors: Jakubus Aneta , Soiński Marek Sławomir , Mierzwa Piotr , Stradomski Grzegorz
Published: October 2024

The study examined the effect of heat treatment parameters of compacted graphite iron (CGI) on the mechanical properties of the material. The microstructure was characterized using optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Three levels of heat treatment parameters were adopted considering the orthogonal test plan 24. The effects of austenitizing temperature and time and austempering on tensile strength, yield strength, and elongation were analyzed. Polynomial regression was chosen because it extends linear regression and allows for modeling more complex, nonlinear relationships between variables. Total regression models were determined for each dataset. The models for tensile strength (Rm) had an approximately 82% coefficient of determination, for yield strength (R0.2) around 50%, and for elongation (A5) around 80%. For optimization, the response surface method (RSM) was used. The results obtained were compared with the proposed mathematical models. The ANOVO results showed that austempering temperature (Tpi) had the greatest effect on each parameter studied. The optimal conditions for the analyzed parameters, assuming tensile strength and yield strength at the maximum level and an elongation of about 0.7%, are obtained for the following heat treatment parameters: Tγ = 890 °C; Tpi = 290 °C; τγ = 120 min; τpi = 150 min.
Super-Resolution Processing for Multiple Aperture Antenna to Suppress Multipath
Authors: Park Jeongho , Kim Eunhee
Published: October 2024

Angle estimation for low-altitude targets above the sea surface is a challenging problem due to multipath interference from surface reflection signals, and various approaches have been proposed. This paper proposes a matrix pencil method with multiple apertures. The matrix pencil method effectively responds to dynamic scenarios because it performs better when using a single snapshot than other methods. Also, employing multiple apertures is more economical than using one large aperture. Therefore, we propose a computationally efficient approach using this method and structures. The proposed two-stage MP method incrementally improves the resolution in two stages: in stage 1, we extract the denoised signals at each aperture level, and in stage 2, we further improve the resolution with those signals. In comparison with the angular resolution defined by the half-power beamwidth (HPBW) of a uniform linear array (ULA) antenna with an equivalent number of arrays, the proposed method demonstrated a superior resolution of less than 0.087 of the HPBW at a high signal-to-noise ratio (SNR) of 40 dB, and less than 0.31 of it even at a relatively low SNR of 15 dB, based on 90% of the resolving probability. For the multipath problem, the proposed scheme has the advantage of not requiring prior geometric information, and its performance is demonstrated through simulations to be better than the adaptive beamforming method and the composite monopulse method.
Smooth Sigmoid Surrogate (SSS): An Alternative to Greedy Search in Decision Trees
Authors: Su Xiaogang , Quaye George Ekow , Wei Yishu , Kang Joseph , Liu Lei , Yang Qiong , Fan Juanjuan , Levine Richard A.
Published: October 2024

Greedy search (GS) or exhaustive search plays a crucial role in decision trees and their various extensions. We introduce an alternative splitting method called smooth sigmoid surrogate (SSS) in which the indicator threshold function used in GS is approximated by a smooth sigmoid function. This approach allows for parametric smoothing or regularization of the erratic and discrete GS process, making it more effective in identifying the true cutoff point, particularly in the presence of weak signals, as well as less prone to the inherent end-cut preference problem. Additionally, SSS provides a convenient means of evaluating the best split by referencing a parametric nonlinear model. Moreover, in many variants of recursive partitioning, SSS can be reformulated as a one-dimensional smooth optimization problem, rendering it computationally more efficient than GS. Extensive simulation studies and real data examples are provided to evaluate and demonstrate its effectiveness.
Constraint Qualifications and Optimality Conditions for Nonsmooth Semidefinite Multiobjective Programming Problems with Mixed Constraints Using Convexificators
Authors: Upadhyay Balendu Bhooshan , Singh Shubham Kumar , Stancu-Minasian Ioan
Published: October 2024

In this article, we investigate a class of non-smooth semidefinite multiobjective programming problems with inequality and equality constraints (in short, NSMPP). We establish the convex separation theorem for the space of symmetric matrices. Employing the properties of the convexificators, we establish Fritz John (in short, FJ)-type necessary optimality conditions for NSMPP. Subsequently, we introduce a generalized version of Abadie constraint qualification (in short, NSMPP-ACQ) for the considered problem, NSMPP. Employing NSMPP-ACQ, we establish strong Karush-Kuhn-Tucker (in short, KKT)-type necessary optimality conditions for NSMPP. Moreover, we establish sufficient optimality conditions for NSMPP under generalized convexity assumptions. In addition to this, we introduce the generalized versions of various other constraint qualifications, namely Kuhn-Tucker constraint qualification (in short, NSMPP-KTCQ), Zangwill constraint qualification (in short, NSMPP-ZCQ), basic constraint qualification (in short, NSMPP-BCQ), and Mangasarian-Fromovitz constraint qualification (in short, NSMPP-MFCQ), for the considered problem NSMPP and derive the interrelationships among them. Several illustrative examples are furnished to demonstrate the significance of the established results.
Short-Term Prediction of Origin–Destination Passenger Flow in Urban Rail Transit Systems with Multi-Source Data: A Deep Learning Method Fusing High-Dimensional Features
Authors: Su Huanyin , Mo Shanglin , Dai Huizi , Shen Jincong
Published: October 2024

Short-term origin–destination (OD) passenger flow forecasting is crucial for urban rail transit enterprises aiming to optimise transportation products and increase operating income. As there are large-scale OD pairs in an urban rail transit system, OD passenger flow cannot be obtained in real time (temporal hysteresis). Additionally, the distribution characteristics are also complex. Previous studies mainly focus on passenger flow prediction at metro stations, while few methods solve the OD passenger flow prediction problems of an urban rail transit system. In view of this, we propose a novel deep learning method fusing high-dimensional features (HDF-DL) with multi-source data. The HDF-DL method is combined with three modules. The temporal module incorporates the time-varying, trend, and cyclic characteristics of OD passenger flow, while the latest OD passenger flow time sequence (within 1 h) is excluded from the time-varying characteristics. In the spatial module, the K-means and K-shape algorithms are used to classify OD pairs from multiple perspectives and capture the spatial features, reducing the difficulty of OD passenger flow predictions with large-scale and complex characteristics. Weather factors are considered in the external feature module. The HDF-DL method is tested on a large-scale metro system in China, in which eight baseline models are designed. The results show that the HDF-DL method achieves high prediction accuracy across multiple time granularities, with a mean absolute percentage error of about 10%. OD passenger flow in every departure time interval can be predicted with high and stable accuracy, effectively capturing temporal characteristics. The modular design of HDF-DL, which fuses high-dimensional features and employs appropriate neural networks for different data types, significantly reduces prediction errors and outperforms baseline models.
Proteomic Analysis and Biochemical Characterization of the Nematocyst Extract of the Hydrozoan Velella velella
Authors: Tassara Eleonora , Mikšík Ivan , Pompach Petr , Mariottini Gian Luigi , Xiao Liang , Giovine Marco , Pozzolini Marina
Published: October 2024

The venom contained within cnidarian nematocysts has a complex composition and holds significant potential for biotechnological applications. In this context, one of the most effective methods for studying nematocyst contents is the proteomic approach, which can detect even trace amounts of compounds while minimizing the need for large-scale animal collection, thus helping to preserve ecosystem integrity. This study aimed to provide a comprehensive proteomic and biochemical characterization of the crude nematocyst extract from the common hydrozoan Velella velella. Despite not being harmful to humans, the analysis of the crude venom extract from V. velella brought to the identification of 783 different proteins, categorized into structural components, enzymes, and potential toxins, revealing a qualitative composition of the venom similar to that of other more toxic cnidarians. Biochemical assays confirmed the presence of various active hydrolytic enzymes within the extract, including proteases, phospholipases, hyaluronidases, DNases, and chitinases. These findings pave the road for future studies involving the pharmacological applications of Velella velella venom components through recombinant production and functional testing.
Protective Effects of Astaxanthin against Oxidative Stress: Attenuation of TNF-α-Induced Oxidative Damage in SW480 Cells and Azoxymethane/Dextran Sulfate Sodium-Induced Colitis-Associated Cancer in C57BL/6 Mice
Authors: Zhang Haifeng , Wang Min , Zhou Yu , Bao Shaojie , Wang Feng , Li Chunmei
Published: October 2024

In this study, we investigated the protective effects of astaxanthin (AST) against oxidative stress induced by the combination of azoxymethane (AOM) and dextran sulfate sodium (DSS) in colitis-associated cancer (CAC) and TNF-α-induced human colorectal cancer cells (SW480), as well as the underlying mechanism. In vitro experiments revealed that astaxanthin reduced reactive oxygen species (ROS) generation and inhibited the expression of Phosphorylated JNK (P-JNK), Phosphorylated ERK (P-ERK), Phosphorylated p65 (P-p65), and the NF-κB downstream protein cyclooxygenase-2 (COX-2). In vivo experiments showed that astaxanthin ameliorated AOM/DSS-induced weight loss, shortened the colon length, and caused histomorphological changes. In addition, astaxanthin suppressed cellular inflammation by modulating the MAPK and NF-κB pathways and inhibiting the expression of the proinflammatory cytokines IL-6, IL-1β, and TNF-α. In conclusion, astaxanthin attenuates cellular inflammation and CAC through its antioxidant effects.
Choroidal and Choriocapillaris Changes after Photodynamic Therapy and Subthreshold Micropulse Laser Treatment for Central Serous Chorioretinopathy
Authors: Ruggeri Maria Ludovica , Di Nicola Marta , Passamonti Marzia , Lorenzi Carolina , Quarta Alberto , Mastropasqua Rodolfo , Toto Lisa
Published: October 2024

Background and Objectives: The aim of the present study is to analyze choroidal and choriocapillaris structural and functional changes in eyes affected by Central serous chorioretinopathy after Photodynamic Therapy (PDT) and Subthreshold Micropulse laser (SML) treatment. Materials and Methods: Forty-two eyes of forty-two patients were analyzed in this observational study. Twenty-four patients underwent SML treatment, whereas eighteen patients were treated with PDT. Examinations were performed at baseline and after 3 months of treatment. Main outcome measures were: Best corrected visual acuity (BCVA), central macular thickness (CMT), central choroidal thickness (CCT), pigment epithelial detachment (PED) presence and maximum height (PEDMH), and choroidal vascularity index (CVI) measured by means of Spectralis HRA + OCT (Heidelberg Engineering, Heidelberg, Germany) Optical coherence tomography (OCT) and choriocapillaris flow voids (CCFV) measured on Optical Coherence Tomography Angiography (OCT-A) platform PLEX Elite 9000 device (Carl Zeiss Meditec Inc., Dublin, CA, USA). Results: Changes in BCVA were registered in both groups over time (p < 0.001). Structural changes in terms of reduced CMT and PED presence were noted in the two groups at follow-up (p < 0.001 and p = 0.001, respectively). Structural and functional choroidal changes were found in the two groups with reduced CCT and CVI over time (p = 0.004 and p = 0.007, respectively), with significant differences between the two groups for CVI parameter (p = 0.001). CCFV increased over time in the PDT group and decreased in the SML group. Conclusions: PDT and SML are effective approaches in CSC eyes and are able to improve structural and functional parameters over time. Choroidal and choriocapillaris parameters are promising biomarkers able to monitor disease course, showing greater impact of PDT on choroid-choriocapillaris complex over time.
Treatment Modalities for Refractory-Recurrent Tenosynovial Giant Cell Tumor (TGCT): An Update
Authors: Dania Vasiliki , Stavropoulos Nikolaos A. , Gavriil Panayiotis , Trikoupis Ioannis , Koulouvaris Panagiotis , Savvidou Olga D. , Mavrogenis Andreas F. , Papagelopoulos Panayiotis J.
Published: October 2024

Background and Objectives: Tenosynovial giant cell tumor (TGCT) is a rare, locally aggressive, benign neoplasm arising from the synovium of joints, tendon sheaths, and bursa. There are two main subtypes of TGCT: localized-type TGCT(L-TGCT) and diffuse-type TGCT (D-TGCT). While surgical excision is still considered the gold standard of treatment, the high recurrence rate, especially for D-TGCT, may suggest the need for other treatment modalities. Materials and Methods: This study reviews current literature on the current treatment modalities for refractory-relapsed TGCT disease. Results: The gold standard of treatment modality in TGCT remains surgical excision of the tumor nevertheless, the elevated recurrence rate and refractory disease, particularly in D-TGCT indicates and underscores the necessity for additional treatment alternatives. Conclusions: TGCT is a benign tumor with inflammatory features and a potential destructive and aggressive course that can lead to significant morbidity and functional impairment with a high impact on quality of life. Surgical resection remains the gold standard current treatment and the optimal surgical approach depends on the location and extent of the tumor. Systemic therapies have been recently used for relapsed mainly cases.
Quantitative Evaluation of Microcirculatory Alterations in Patients with COVID-19 and Bacterial Septic Shock through Remote Photoplethysmography and Automated Capillary Refill Time Analysis
Authors: Klibus Mara , Smirnova Darja , Marcinkevics Zbignevs , Rubins Uldis , Grabovskis Andris , Vanags Indulis , Sabelnikovs Olegs
Published: October 2024

Background and Objectives: Sepsis, a leading global health challenge, accounts for around 20% of deaths worldwide. The complexity of sepsis, especially the difference between bacterial and viral etiologies, requires an effective assessment of microcirculation during resuscitation. This study aimed to evaluate the impact of infusion therapy on microcirculation in patients with sepsis, focusing on bacterial- and COVID-19-associated sepsis using remote photoplethysmography (rPPG) and the automated capillary refill time (aCRT). Materials and Methods: This single-center prospective study was conducted in the ICU of Pauls Stradins Clinical University Hospital, including 20 patients with sepsis/septic shock. The patients were selected based on hemodynamic instability and divided into COVID-19 and Bacterial Septic Shock groups. Fluid responsiveness was assessed using the Passive Leg Raising Test (PLRT). Systemic hemodynamics and microcirculation were monitored through MAP CRT, rPPG, and serum lactate levels. Statistical analyses compared responses within and between the groups across different stages of the protocol. Results: The Bacterial group exhibited higher initial serum lactate levels and more pronounced microcirculatory dysfunction than the COVID-19 group. rPPG was more sensitive in detecting perfusion changes, showing significant differences between the groups. The automated CRT demonstrated greater sensitivity compared to the manual CRT, revealing significant differences during PLRT stages between bacterial- and COVID-19-associated sepsis. Both groups had a transient hemodynamic response to PLRT, with subsequent stabilization upon fluid infusion. Conclusions: When managing patients with sepsis in intensive care, monitoring microcirculation is of paramount importance in infusion therapy. Our study highlights the potential of rPPG and aCRT as tools for this purpose. These techniques can be used in conjunction with routine parameters, such as lactate levels and systemic hemodynamic parameters, to provide a comprehensive assessment of a patient’s condition.