bluuebunny/crossref_metadata_2025 huggingface dataset:
Variation of the Tegmen and Cercus in Sinopodisma rostellocerca (Orthoptera: Acrididae: Melanoplinae) with Proposal of a New Synonym
Authors: Qiu Renjie , Yan Yuchen , Wang Hanqiang , Huang Jianhua
Published: July 2024

Intraspecific variation is ubiquitous from individual traits to population level and plays an important role in a variety of fields. However, it is often ignored by systematists and comparative evolutionary biologists. In view of the limited knowledge of intraspecific variation, morphology-based identification has hindered the recognition of species borders and led to a great number of problems in the field of taxonomy and systematics. In this study, the intraspecific variation of the tegmen and cercus in Sinopodisma rostellocerca was examined, the variation patterns were summarized and the relationship between S. rostellocerca and S. hengshanica was discussed. The results showed that the intraspecific variation in the tegmen and male cercus was mainly manifested in the length and shape of the apical margin and dorso- and ventro-apical angles; this substantial variation occurred not only among intrapopulation individuals but also between the different sides of the same individuals, and all types of variation in S. hengshanica fell into the range of variation in S. rostellocerca, leading to the disappearance of the boundary between the two species. Therefore, S. hengshanica was herein considered as a new junior synonym of S. rostellocerca.
Analysis of a Newly Developed Afterburner System Employing Hydrogen–Methane Blends
Authors: Florean Florin Gabriel , Mangra Andreea , Enache Marius , Carlanescu Razvan , Taranu Alexandra , Botu Madalina
Published: July 2024

A considerable number of Combined Heat and Power (CHP) systems continue to depend on fossil fuels like oil and natural gas, contributing to significant environmental pollution and the release of greenhouse gases. Two V-gutter flame holder prototypes (P1 and P2) with the same expansion angle, fueled with pure hydrogen (100% H2) or hydrogen–methane mixtures (60% H2 + 40% CH4, 80% H2 + 20% CH4), intended for use in cogeneration applications, have been designed, manufactured, and tested. Throughout the tests, the concentrations of CO2, CO, and NO in the flue gas were monitored, and particle image velocimetry (PIV) measurements were performed. The CO, CO2, respectively, and NO emissions gradually decreased as the percentage of H2 in the fuel mixture increased. The NO emissions were significantly lower in the case of prototype P2 in comparison with prototype P1 in all measurement points for all used fuel mixtures. The shortest recirculation zone was observed for P1, where the axial velocity reaches a negative peak of approximately 12 m/s at roughly 50 mm downstream of the edge of the flame holder, and the recirculation region spans about 90 mm. In comparison, the P2 prototype has a length of the recirculation region span of about 100 mm with a negative peak of approximately 14 m/s. The data reveal high gradients in flow velocity near the flow separation point, which gradually smooth out with increasing downstream distance. Despite their similar design, P2 consistently performs better across all measured velocity components. This improvement can be attributed to the larger fuel injection holes, which enhance fuel–air mixing and combustion stability. Additionally, the presence of side walls directing the flow around the flame stabilizer further aids in maintaining a stable combustion process.
Diagnostic Modalities in the Detection of Cardiac Amyloidosis
Authors: Bukhari Syed , Bashir Zubair
Published: July 2024

Cardiac amyloidosis (CA) results mainly from the infiltration of the myocardium by either immunoglobulin light-chain fibrils (AL) or transthyretin fibrils (ATTR), causing restrictive cardiomyopathy and eventually death if untreated. AL derives from monoclonal immunoglobulin light chains produced by plasma cell clones in the bone marrow, while ATTR is the misfolded form of hepatically derived transthyretin (TTR) protein and can be hereditary (ATTRv) or wild-type (ATTRwt). Over the last decade, improvements in diagnostic imaging and better clinical awareness have unleashed a notable presence of CA in the community, especially ATTR in the elderly population. These multimodality imaging modalities include echocardiography, cardiac magnetic resonance, and radionuclide scintigraphy with bone-avid tracers. There has been remarkable progress in the therapeutic landscape as well, and there are disease-modifying therapies available now that can alter the course of the disease and improve survival if initiated at an early stage of the disease. There remains an unmet need for detecting this disease accurately and early so that these patients can benefit the most from newly emerging therapies.
Application of Palladium Mesoporous Carbon Composite Obtained from a Sustainable Source for Catalyzing Hydrogen Generation Reaction
Authors: Biehler Erik , Quach Qui , Abdel-Fattah Tarek M.
Published: July 2024

Alternative fuel sources are necessary in today’s economic and environmental climate. Hydrogen fuel arises as an environmentally friendly and energy dense option; however, the volatility of hydrogen gas makes it dangerous to store and utilize. The evolution of hydrogen from hydrogen feedstock materials may prove to overcome this safety barrier, but a catalyst for this reaction is necessary to optimize production. In this work, a composite catalyst comprised of palladium nanoparticles embedded on mesoporous carbon materials (Pd-MCM) was synthesized and characterized by Transmission Electron Microscope (TEM), Powder X-Ray diffraction (P-XRD), Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscope (EDS). Various reaction conditions such as concentration of reactant, temperature, and pH were applied in measuring the catalytic activity of Pd-MCM. Results show the catalytic activity of the Pd-MCM composite catalysts increased with increasing concentrations of sodium borohydride, increasing temperature, and lower pH. The reaction involving the Pd-MCM composite had an activation energy of 27.9 kJ mol−1. Reusability trials showed the Pd-MCM composite remained stable for up to five consecutive trials.
Convolutional Neural Network-Based Automated Segmentation of Skeletal Muscle and Subcutaneous Adipose Tissue on Thigh MRI in Muscular Dystrophy Patients
Authors: Aringhieri Giacomo , Astrea Guja , Marfisi Daniela , Fanni Salvatore Claudio , Marinella Gemma , Pasquariello Rosa , Ricci Giulia , Sansone Francesco , Sperti Martina , Tonacci Alessandro , Torri Francesca , Matà Sabrina , Siciliano Gabriele , Neri Emanuele , Santorelli Filippo Maria , Conte Raffaele
Published: July 2024

We aim to develop a deep learning-based algorithm for automated segmentation of thigh muscles and subcutaneous adipose tissue (SAT) from T1-weighted muscle MRIs from patients affected by muscular dystrophies (MDs). From March 2019 to February 2022, adult and pediatric patients affected by MDs were enrolled from Azienda Ospedaliera Universitaria Pisana, Pisa, Italy (Institution 1) and the IRCCS Stella Maris Foundation, Calambrone-Pisa, Italy (Institution 2), respectively. All patients underwent a bilateral thighs MRI including an axial T1 weighted in- and out-of-phase (dual-echo). Both muscles and SAT were manually and separately segmented on out-of-phase image sets by a radiologist with 6 years of experience in musculoskeletal imaging. A U-Net1 and U-Net3 were built to automatically segment the SAT, all the thigh muscles together and the three muscular compartments separately. The dataset was randomly split into the on train, validation, and test set. The segmentation performance was assessed through the Dice similarity coefficient (DSC). The final cohort included 23 patients. The estimated DSC for U-Net1 was 96.8%, 95.3%, and 95.6% on train, validation, and test set, respectively, while the estimated accuracy for U-Net3 was 94.1%, 92.9%, and 93.9%. Both of the U-Nets achieved a median DSC of 0.95 for SAT segmentation. The U-Net1 and the U-Net3 achieved an optimal agreement with manual segmentation for the automatic segmentation. The so-developed neural networks have the potential to automatically segment thigh muscles and SAT in patients affected by MDs.
Epidemiology of Candidemia in Mashhad, Northeast Iran: A Prospective Multicenter Study (2019–2021)
Authors: Dolatabadi Somayeh , Najafzadeh Mohammad Javad , Raeisabadi Abbas , Zarrinfar Hossein , Jalali Mahsa , Spruijtenburg Bram , Meijer Eelco F. J. , Meis Jacques F. , Lass-Flörl Cornelia , de Groot Theun
Published: July 2024

Candidemia is a major cause of morbidity and mortality in health care settings, and its epidemiology is changing. In the last two decades, the proportion of non-albicans Candida (NAC) yeasts in candidemia has increased. These yeasts more often display resistance to common antifungals. In many western countries, candidemia is mainly caused by susceptible C. albicans, while in resource-limited countries, including Iran, the candidemia species distribution is studied less often. Here, we investigated the species distribution, resistance levels, and characteristics of patients with candidemia in five hospitals in Mashhad (northeast Iran) for two years (2019–2021). Yeast isolates from blood were identified with MALDI-TOF MS and subjected to antifungal susceptibility testing (AFST) using the broth microdilution method, while molecular genotyping was applied to Candida parapsilosis isolates. In total, 160 yeast isolates were recovered from 160 patients, of which the majority were adults (60%). Candidemia was almost equally detected in men (48%) and women (52%). Almost half of patients (n = 67, 49%) were from intensive care units (ICUs). C. parapsilosis (n = 58, 36%) was the most common causative agent, surpassing C. albicans (n = 52, 33%). The all-cause mortality rate was 53%, with C. albicans candidemia displaying the lowest mortality with 39%, in contrast to a mortality rate of 59% for NAC candidemia. With microbroth AFST, nearly all tested isolates were found to be susceptible, except for one C. albicans isolate that was resistant to anidulafungin. By applying short tandem repeat (STR) genotyping to C. parapsilosis, multiple clusters were found. To summarize, candidemia in Mashhad, Iran, from 2019 to 2021, is characterized by common yeast species, in particular C. parapsilosis, for which STR typing indicates potential nosocomial transmission. The overall mortality is high, while resistance rates were found to be low, suggesting that the high mortality is linked to limited diagnostic options and insufficient medical care, including the restricted use of echinocandins as the first treatment option.
Identification of Lipid Droplet-Associated Genes in Breast Cancer Patients
Authors: Dogan Senol , Leopold Jenny , Hoffmann Daniel T. , Kubitschke Hans , Blauth Eliane , Ficorella Carlotta , Zschau Amelie , Schiller Jürgen , Käs Josef A.
Published: July 2024

Lipid droplets (LDs) are known to be involved in the invasion and migration of breast cancer (BC) cells. This study aimed to identify LD-associated genes as prognostic markers in BC through comprehensive literature research and integration with lipid composition studies in BC cell lines. The GEPIA platform was used to analyze the differential expression of LD-associated genes in BC. The lipid composition of cell lines (MCF-10A, MDA-MB 436 and 231) was obtained by extraction and thin-layer chromatography coupled with mass spectrometry (MS). Additionally, cell lines were co-cultured with fatty tissue and analyzed by confocal fluorescence microscopy. A total of 143 genes were identified as LD-associated genes through literature research and were subsequently analyzed using GEPIA. Among these, three genes were found to be over-expressed and 45 under-expressed in BC. Notably, FABP7 showed a statistically significant rank for all bioinformatics criteria as a prognostic factor. Experimental results showed only minor changes from MCF-10A to both MDA-MB cell lines for apolar lipids (triacylglycerols and cholesteryl esters) compared to phospholipids (PLs). Microscopic analyses showed that MDA-MB-231 had larger LDs compared to MCF-10A after 10 days of cultivation. Our bioinformatics analysis identified 26 genes that play important roles in metastatic transition in BC via LD-related mechanisms, though these findings could be only partially confirmed by experimental lipid compositional analyses, so far.
Influence of Low pH on the Microhardness and Roughness Surface of Dental Composite—A Preliminary Study
Authors: Szalewski Leszek , Wójcik Dorota , Sowa Monika , Vivcharenko Vladyslav , Pałka Krzysztof
Published: July 2024

Dental composites are gaining great popularity in restorative dentistry because of their aesthetic appeal and capacity to replicate the natural color of teeth. Nevertheless, their lifespan and durability rely on various factors, such as the polishing technique and the environmental conditions they are exposed to. The study aimed to assess the influence of the method of final polishing of dental composite on the surface roughness and microhardness of materials also considering the environment of different pHs. Disc-shaped samples (5 mm diameter and 2 mm thickness) have been prepared for microhardness and roughness tests from two dental composites: A2 Clearfil Majesty ES 2 Classic and A2D Clearfil Majesty Premium. One-third of samples were polished with polishing discs, OptiDisc, another one-third of samples were polished with Eve Diacomp Twist rubbers and polishing brush with diamond particles, and rest of the samples were stored without any polishing (the control group). Tested materials were incubated in distilled water or acidic buffer (pH = 2) for 3 weeks at a temperature of 37 °C. No statistically significant differences were found for roughness for the two materials tested after incubation in liquids. A decrease in Vicker microhardness was found for Clearfil Majesty ES 2 Classic after soaking in a low pH liquid, and no such relationship was found for Clearfil Majesty Premium. The improved resistance of these materials to the negative oral environment may result in the longer survival of composite restorations in patients with poor diet or diseases, causing a decrease in oral pH.
On Morphology of Aluminum–Gallium Nitride Layers Grown by Halide Vapor Phase Epitaxy: The Role of Total Reactants’ Pressure and Ammonia Flow Rate
Authors: Jaroszynska Arianna , Dabrowski Michal , Sadovy Petro , Bockowski Michal , Czernecki Robert , Sochacki Tomasz
Published: July 2024

The focus of this study was the investigation of how the total pressure of reactants and ammonia flow rate influence the growth morphology of aluminum–gallium nitride layers crystallized by Halide Vapor Phase Epitaxy. It was established how these two critical parameters change the supersaturation levels of gallium and aluminum in the growth zone, and subsequently the morphology of the produced layers. A halide vapor phase epitaxy reactor built in-house was used, allowing for precise control over the growth conditions. Results demonstrate that both total pressure and ammonia flow rate significantly affect the nucleation and crystal growth processes which have an impact on the alloy composition, surface morphology and structural quality of aluminum–gallium nitride layers. Reducing the total pressure and adjusting the ammonia flow rate led to a notable enhancement in the homogeneity and crystallographic quality of the grown layers, along with increased aluminum incorporation. This research contributes to a deeper understanding of the growth mechanisms involved in the halide vapor phase epitaxy of aluminum–gallium nitride, and furthermore it suggests a trajectory for the optimization of growth parameters so as to obtain high-quality materials for advanced optoelectronic and electronic applications.
Effect of Continuous Casting and Heat Treatment Parameters on the Microstructure and Mechanical Properties of Recycled EN AW-2007 Alloy
Authors: Mrówka-Nowotnik Grażyna , Boczkal Grzegorz , Nowotnik Andrzej
Published: July 2024

The growing use of aluminum and its compounds has increased the volume of aluminum waste. To mitigate environmental impacts and cut down on manufacturing expenses, extensive investigations have recently been undertaken to recycle aluminum compounds. This paper outlines the outcomes of a study on fabricating standard EN AW-2007 alloy using industrial and secondary scrap through continuous casting. The resultant recycled bars were analyzed for their chemical makeup and examined for microstructural features in both the cast and T4 states, undergoing mechanical property evaluations. The study identified several phases in the cast form through LM, SEM + EDS, and XRD techniques: Al7Cu2Fe, θ-Al2Cu, β-Mg2Si, Q-Al4Cu2Mg8Si7, and α-Al15(FeMn)3 (SiCu)2, along with Pb particles. Most primary intermetallic precipitates such as θ-Al2Cu, β-Mg2Si, and Q-Al4Cu2Mg8Si7 dissolved into the α-Al solid solution during the solution heat treatment. In the subsequent natural aging process, the θ-Al2Cu phase predominantly emerged as a finely dispersed hardening phase. The peak hardness achieved in the EN AW-2007 alloy was 124.8 HB, following a solution heat treatment at 500 °C and aging at 25 °C for 80 h. The static tensile test assessed the mechanical and ductility properties of the EN AW-2007 alloy in both the cast and T4 heat-treated states. Superior strength parameters were achieved after solution heat treatment at 500 °C for 6 h, followed by water quenching and natural aging at 25 °C/9 h, with a tensile strength of 435.0 MPa, a yield strength of 240.5 MPa, and an appreciable elongation of 18.1% at break. The findings demonstrate the feasibility of producing defect-free EN AW-2007 alloy ingots with excellent mechanical properties from recycled scrap using the continuous casting technique.
Effects of Impurities and Ageing on the Functional and Rheological Properties of Asphalts with Additives from Recovered and Pyrolysis-Processed Plastics
Authors: Gajewski Marcin Daniel , Horodecka Renata , Bańkowski Wojciech , Mirski Krzysztof , Grzegórska Aleksandra , Kłopociński Maciej
Published: July 2024

This article is a continuation of work on the use of plastic waste (such as PP, PS, LDPE, HDPE, and their mixtures) processed in the proprietary pyrolysis process as asphalt additives. The article carried out detailed tests of the mixes of selected additives with pen-graded bitumen 50/70, taking into account, among others, the influence of impurities and the ratio of PE to PP in the additives as well as short- (RTFOT) and long-term (RTFOT + PAV) ageing. An extensive research program was carried out, including functional and rheological tests in a wide range of temperatures. First, tests of stability and adhesion to various types of aggregates were carried out, demonstrating the usefulness of the proposed additives. Then, the elastic recovery and the impact of technological ageing on penetration, Fraass breaking temperature, and plasticity range were assessed. The same binder mixes were subjected to rheological tests in a wide range of technological and operational temperatures, assessing, among others, viscosity, the norm of the complex shear modulus, elastic recovery and compliance in the MSCR test, and stiffness in the bending beam rheometer. This entire class of tests was carried out for clean samples and those containing impurities, indicating their impact on individual material parameters.
Inclusion Removal Process of Homogeneous CuCr50 Alloy In-Situ Synthesized by Al-Mg Composite Strengthening Reduction Coupling Slagging
Authors: An Wang , Dou Zhihe , Zhang Tingan , Han Jinru
Published: July 2024

To overcome the problem of Cr2O3 and Al2O3 inclusions in CuCr50 alloy prepared by aluminothermic reduction method, in this paper, a novel methodology for strengthening metal–slag separation through in situ slagging is proposed. CuCr50 alloys were prepared by metallothermic reduction using Al and Al-Mg as reducing agents, and the physical properties of the slag, such as viscosity, density, and surface tension, were adjusted by controlling the proportion of CaO in the slagging agent in the raw material to achieve good separation of the slag–metal. The results show that with the ratio of CaO increased, CaO and MgO were coupled to make slag, which combined with Cr2O3 and Al2O3 to form CaCr2O4, MgCr2O4, and CaAl4O7 in the slag, thus reducing the content of impurities in the alloy. When RCaO/(CaO + Al2O3 + MgO) = 20%, the Cr content ranged from 46.61% to 47.09%, the inclusions accounted for 1.60%, the Cr particle size was refined to 20 µm, the number of Cr spherical crystals accounted for 9.88%, the conductivity reached 14.96 MS/m, and the hardness reached 100.23 HB. After heat treatment, the Cr phase was refined in the alloy, the conductivity increased from 14.96 MS/m to 18.27 MS/m, and the hardness increased from 100.23 HB to 103.1 HB. This method is expected to provide an effective method for the preparation of CuCr50 contact materials.
Application of Silicone in Ophthalmology: A Review
Authors: Mladenovic Tamara , Zivic Fatima , Petrovic Nenad , Njezic Sasa , Pavic Jelena , Kotorcevic Nikola , Milenkovic Strahinja , Grujovic Nenad
Published: July 2024

This paper reviews the latest trends and applications of silicone in ophthalmology, especially related to intraocular lenses (IOLs). Silicone, or siloxane elastomer, as a synthetic polymer, has excellent biocompatibility, high chemical inertness, and hydrophobicity, enabling wide biomedical applications. The physicochemical properties of silicone are reviewed. A review of methods for mechanical and in vivo characterization of IOLs is presented as a prospective research area, since there are only a few available technologies, even though these properties are vital to ensure medical safety and suitability for clinical use, especially if long-term function is considered. IOLs represent permanent implants to replace the natural lens or for correcting vision, with the first commercial foldable lens made of silicone. Biological aspects of posterior capsular opacification have been reviewed, including the effects of the implanted silicone IOL. However, certain issues with silicone IOLs are still challenging and some conditions can prevent its application in all patients. The latest trends in nanotechnology solutions have been reviewed. Surface modifications of silicone IOLs are an efficient approach to further improve biocompatibility or to enable drug-eluting function. Different surface modifications, including coatings, can provide long-term treatments for various medical conditions or medical diagnoses through the incorporation of sensory functions. It is essential that IOL optical characteristics remain unchanged in case of drug incorporation and the application of nanoparticles can enable it. However, clinical trials related to these advanced technologies are still missing, thus preventing their clinical applications at this moment.
The Main Failure Modes of Hot-Work Die Steel and the Development Status of Traditional Strengthening Methods and Nano-Strengthening Technology
Authors: Cui Hong-Yu , Bao Ze-Ju , Gong Qin , Bao Shi-Zhe , Zou Yun-Zhi , Li Ai-Min , Yang Hong-Yu , Wang Cheng-Gang , Li Zhi-Gang , Chang Fang , Shu Shi-Li , Kang Jie , Zhu Ming , Qiu Feng , Jiang Qi-Chuan
Published: July 2024

As an important part of die steels, hot-work die steels are mainly used to manufacture molds made of solid metal or high-temperature liquid metal from heating to recrystallization temperature. In view of the requirements for mechanical properties and service life for hot-work die steel, it is conducive to improve the thermal fatigue resistance, wear resistance, and oxidation resistance of hot work die steel. In this review, the main failure modes of hot-work die steel were analyzed. Four traditional methods of strengthening and toughening die steel were summarized, including optimizing alloying elements, electroslag remelting, increasing the forging ratio, and heat treatment process enhancement. A new nano-strengthening method was introduced that aimed to refine the microstructure of hot-work abrasive steel and improve its service performance by adding nanoparticles into molten steel to achieve uniform dispersion. This review provides an overview to improve the service performance and service life of hot work die steel.
Evolution of Material Properties and Residual Stress with Increasing Number of Passes in Aluminium Structure Printed via Additive Friction Stir Deposition
Authors: Yakubov Vladislav , Ostergaard Halsey , Hughes James , Yasa Evren , Karpenko Michail , Proust Gwénaëlle , Paradowska Anna M.
Published: July 2024

Additive friction stir deposition (AFSD) is an emerging solid-state additive manufacturing process with a high deposition rate. Being a non-fusion additive manufacturing (AM) process, it significantly eliminates problems related to melting such as cracking or high residual stresses. Therefore, it is possible to process reactive materials or high-strength alloys with high susceptibility to cracking. Although the residual stresses are lower in this process than with the other AM processes, depending on the deposition path, geometry, and boundary conditions, residual stresses may lead to undesired deformations and deteriorate the dimensional accuracy. Thermal cycling during layer deposition, which also depends on the geometry of the manufactured component, is expected to affect mechanical properties. To this day, the influence of the deposit geometry on the residual stresses and mechanical properties is not well understood, which presents a barrier for industry uptake of this process for large-scale part manufacturing. In this study, a stepped structure with 4, 7, and 10 passes manufactured via AFSD is used to investigate changes in microstructure, residual stress, and mechanical property as a function of the number of passes. The microstructure and defects are assessed using scanning electron microscopy and electron backscatter diffraction. Hardness maps for each step are created. The residual stress distributions at the centreline of each step are acquired via non-destructive neutron diffraction. The valuable insights presented here are essential for the successful utilisation of AFSD in industrial applications.
Investigation on the Correlation between Mechanical Strength, Grain Size, and Density of Fly Ash Microspheres in the Context of Refining Process
Authors: Radko Tomasz , Wajda Agata , Iluk Tomasz , Najser Jan
Published: July 2024

Fly ash microspheres, also called cenospheres, have many valuable properties that allow them to be widely used. Some of its most important properties are its mechanical and thermal strength as well as its chemical stability. These features constitute an important commercial parameter. Refining processes aim to select the highest quality product from raw materials that meets the expectations of recipients. Generally, preparing a final product involves selecting the appropriate sequence and parameters of the grain separation process. However, the key to the optimal selection of these parameters is knowledge of the specificity of the processed raw material. Microspheres are materials that are created spontaneously, uncontrolled, and without the possibility of intentionally influencing their properties. Therefore, due to the potential directions of microsphere use, it is justified to study the relationship between density, grain size, and mechanical strength. Understanding these relationships in microspheres from various sources is particularly important at the stage of planning refining processes. This paper presents the results of research on microspheres from two different sources. The tested raw materials (microspheres) are subjected to densiometric and grain analysis. Also, mechanical strength was determined for the separated density fractions and grain classes. The test results did not show significant correlations between the tested features of the microspheres. In the case of both raw materials, the highest density was observed in the smallest grain classes, and the highest mechanical strength was determined for microspheres with grain sizes in the range of 75–100 µm. For this grain size range, the value of mechanical strength is 26 for raw Material 1 and 38 for raw Material 2. The shares of this grain fraction in the microsphere stream are 11.2% and 16%, respectively. An important difference that may significantly affect the efficiency of the refining process is the method of distribution of the primary falling parts, which affects the mechanical strength of the tested raw materials.
Analysis of Tribological Properties of Hardfaced High-Chromium Layers Subjected to Wear in Abrasive Soil Mass
Authors: Lemecha Magdalena , Ligier Krzysztof , Napiórkowski Jerzy , Vrublevskyi Oleksandr
Published: July 2024

This article presents the results of abrasion wear resistance tests of wear-resistant steel and surfacing under laboratory conditions and natural operation. Abrasion wear resistance determined on the basis of the study by determining geometrical characteristics of the alloying additives using computer image analysis methods, as well as examining the changes occurring on the surface of the workpieces and their wear intensity. Based on the results obtained from laboratory tests, it was noted that AR steel exhibited 14 times greater wear than the padding weld. This wear is affected by alloy additives, which, for the padding weld, are chromium additives. The microstructure image shows that soil mass had a destructive effect mainly on the matrix of the material, whereas in the areas with high concentrations of chromium precipitates, this effect was significantly weaker. The operational test results showed that within the area of the tine subjected to hardfacing, the material loss was lower than that for the same area of the tine in the as-delivered state. For the hardfaced tine, a 7% loss of volume was noted in relation to the operating part before testing and following the friction process. However, for the operating part in the as-delivered state, this difference amounted to 12%.
Radioactive Attenuation Using Different Types of Natural Rocks
Authors: Abd El-Azeem S. A. , Harpy Nareman M.
Published: July 2024

Humans benefit from nuclear technology, but it also generates nuclear radiation that is bad for both the environment and human health. The serious issue of radiation leakage affects many technological applications. Shielding is required to protect both users and the environment from negative side effects. This work describes the radioactive attenuation properties of some natural rocks, such as claystone, bentonitic claystone, bentonitic shale, sandstone, and basalt using a NaI(Tl) detector. The mass attenuation coefficients μm of these rocks at various photon energies, half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP) were determined. The validation of obtained values of μm was carried out against the theoretical calculations from the XCOM program, and the correlation factor and relative deviation between the two methods were evaluated. It was noted that basalt samples exhibit superior shielding parameters when compared to other rock samples. Also, the concentrations of naturally occurring radioactive elements (238U, 226Ra, 232Th, and 40K) were measured, allowing for the calculation of environmental hazard indices and assessment of attenuation (%) efficiency for certain natural rocks, such as bentonite, sandstone, and basalt. The results revealed that increasing the thickness of Basalt-AZ from 1.5 cm to 2 cm results in an approximate 11% rise in attenuation percentage, with values reaching 77.12%, 67.2%, 67.65%, and 59.8% for NMA-U, IAEA-Th, IAEA-Ra, and IAEA-K, respectively.
Influence of CaCO3 on Density and Compressive Strength of Calcium Aluminate Cement-Based Cementitious Materials in Binder Jetting
Authors: Kim Tae-Hyung , Ye Bora , Jeong Bora , Lee Myeung-Jin , Song Aran , Cho Inkyung , Lee Heesoo , Kim Hong-Dae
Published: July 2024

We investigated the impact of CaCO3 addition on the density and compressive strength of calcium aluminate cement (CAC)-based cementitious materials in binder jetting additive manufacturing (BJAM). To confirm the formation of a uniform powder bed, we examined the powder flowability and powder bed density for CaCO3 contents ranging from 0 to 20 wt.%. Specifically, powders with avalanche angles between 40.1–45.6° formed a uniform powder bed density with a standard deviation within 1%. Thus, a 3D printing specimen (green body) fabricated via BJAM exhibited dimensional accuracy of less than 1% across the entire plane. Additionally, we measured the hydration characteristics of CAC and the changes in compressive strength over 30 days with the addition of CaCO3. The results indicate that the addition of CaCO3 to CAC-based cementitious materials forms multimodal powders that enhance the density of both the powder bed and the green body. Furthermore, CaCO3 promotes the formation of highly crystalline monocarbonate (C4AcH11) and stable hydrate (C3AH6), effectively inhibiting the conversion of CAC and showing compressive strengths of up to 5.2 MPa. These findings suggest a strong potential for expanding the use of BJAM across various applications, including complex casting molds, cores, catalyst supports, and functional architectural interiors.
Thermal Studies of Fractionated Lignite and Brown Coal Fly Ashes
Authors: Delihowski Jurij , Gajek Marcin , Izak Piotr , Jarosz Marcin
Published: July 2024

Coal fly ash (CFA), a by-product of coal combustion, is a valuable raw material for various applications. However, the heterogeneous nature of the composition and properties of CFA provides challenges to its effective usage and utilisation. This study investigates the thermal behaviour of the fly ashes of lignite (FA1) and brown coal (FA2) and their fractions obtained by dry aerodynamic separation. Thermal analysis techniques, including thermogravimetry (TG), differential scanning calorimetry (DSC), and evolved gas analysis (EGA), were used to characterise the behaviour of the fly ash fractions while heating up to 1250 °C. The results reveal distinct differences in the thermal behaviour between ash types and among their different size fractions. For the FA1 ashes, the concentration of calcium-rich compounds and the level of recrystallisation at 950 °C increased with the decrease in particle size. The most abundant detected newly formed minerals were anhydrite, gehlenite, and anorthite, while coarser fractions were rich in quartz and mullite. For the FA2 ashes, the temperature of the onset of melting and agglomeration decreased with decreasing particle size and was already observed at 995 °C. Coarser fractions mostly remain unchanged, with a slight increase in quartz, mullite, and hematite content. Recrystallisation takes place in less extension compared to the FA1 ashes. The findings demonstrate that the aerodynamic separation of fly ashes into different size fractions can produce materials with varied thermal properties and reactivity, which can be used for specific applications. This study highlights the importance of thermal analysis in characterising fly ash properties and understanding their potential for utilisation in various applications involving thermal treatment or exposure to high-temperature conditions. Further research on advanced separation techniques and the in-depth characterisation of fly ash fractions is necessary to obtain materials with desired thermal properties and identify their most beneficial applications.
Mechanical and Antimicrobial Properties of the Graphene-Polyamide 6 Composite
Authors: Głuchowski Paweł , Macieja Marta , Tomala Robert , Stefanski Mariusz , Stręk Wiesław , Ptak Maciej , Szymański Damian , Szustakiewicz Konrad , Junka Adam , Dudek Bartłomiej
Published: July 2024

This paper presents the synthesis and characterization of graphene–polymer composites, focusing on their mechanical and antibacterial properties. Graphene flakes were obtained via an electrochemical method and integrated into polyamide 6 (PA6) matrices using melt intercalation. Various characterization techniques confirmed the quality of the graphene flakes, including X-ray diffraction (XRD), Raman spectroscopy, and infrared (IR) spectroscopy, as well as scanning and transmission electron microscopy (SEM and TEM) imaging. Mechanical tests showed an increase in the elastic modulus with graphene incorporation, while the impact strength decreased. The SEM analysis highlighted the dispersion of the graphene flakes within the composites and their impact on fracture behavior. Antimicrobial tests demonstrated significant antibacterial properties of the composites, attributed to both oxidative stress and mechanical damage induced by the graphene flakes. The results suggest promising applications for graphene–polymer composites in advanced antimicrobial materials.
Dual-Arm Obstacle Avoidance Motion Planning Based on Improved RRT Algorithm
Authors: Dong Zhe , Zhong Binrui , He Jiahuan , Gao Zhao
Published: July 2024

This paper proposes a solution for the cooperative obstacle avoidance path planning problem in dual manipulator arms using an improved Rapidly Exploring Random Tree (RRT) algorithm. The dual manipulator arms are categorized into a main arm and a secondary arm. Initially, the obstacle avoidance path for the master arm is planned in the presence of static obstacles. Subsequently, the poses of the master arm during its movement are treated as dynamic obstacles for planning the obstacle avoidance path for the slave arm. A cost function incorporating a fast convergence policy is introduced. Additionally, adaptive weights between distance cost and variation cost are innovatively integrated into the cost function, along with increased weights for each joint, enhancing the algorithm’s effectiveness and feasibility in practical scenarios. The smoothness of the planned paths is improved through the introduction of interpolation functions. The improved algorithm is numerically modeled and simulated in MATLAB. The verification results demonstrate that the improved RRT algorithm proposed in this paper is both feasible and more efficient.
Testing and Visualization of Associations in Three-Way Contingency Tables: A Study of the Gender Gap in Patients with Type 1 Diabetes and Cardiovascular Complications
Authors: Lombardo Rosaria , Beh Eric J. , Prattichizzo Francesco , Lucisano Giuseppe , Nicolucci Antonio , Eliasson Björn , Carlsen Hanne Krage , Grotta Rosalba La , Pellegrini Valeria , Ceriello Antonio
Published: July 2024

Using data from the Swedish National Diabetes Register, this study examines the gender disparity among patients with type 1 diabetes who have experienced a specific cardiovascular complication, while exploring the association between their weight variability, age group, and gender. Fourteen cardiovascular complications have been considered. This analysis is conducted using three-way correspondence analysis (CA), which allows for the partitioning and decomposition of Pearson’s three-way chi-squared statistic. The dataset comprises information organized in a data cube, detailing how weight variability among these patients correlates with a cardiovascular complication, age group, and gender. The three-way CA method presented in this paper allows one to assess the statistical significance of the association between these variables and to visualize this association, highlighting the gender gap among these patients. From this analysis, we find that the association between weight variability, age group, and gender varies among different types of cardiovascular complications.
Balance and Walking Control for Biped Robot Based on Divergent Component of Motion and Contact Force Optimization
Authors: Heng Shuai , Zang Xizhe , Song Chao , Chen Boyang , Zhang Yue , Zhu Yanhe , Zhao Jie
Published: July 2024

This paper presents a complete planner and controller scheme to achieve balance and walking for a biped robot, which does not need to distinguish the robot’s dynamic model parameters. The high-level planner utilizes model predictive control to optimize both the foothold location and step duration based on the Divergent Component of Motion (DCM) model to enhance the robustness of generated gaits. For low-level control, we use quadratic programming (QP) to optimize the contact force distribution under the contact constraints to achieve the virtual wrench exerted on the base of the robot. Then, the joint torques sent to the robot are derived from three parts: first, the torques mapped from the contact force; second, the swing leg tracking; and third, the stance foot stabilization. The simulation and experiment on BRUCE, a miniature bipedal robot from Westwood Robotics (Los Angeles, CA, USA), testify to the performance of the control scheme, including push recovery, Center of Mass (CoM) tracking, and omnidirectional walking.
Personnel Selection in a Coffee Shop Company Based on a Multi-Criteria Decision-Aiding and Artificial Intelligence Approach
Authors: Gastélum-Chavira Diego Alonso , Ballardo-Cárdenas Denisse , León-Castro Ernesto
Published: July 2024

Human capital management is a strategic element for companies in a globalized world. Therefore, they must use strategies and methods to recruit and select personnel assertively to focus their training, strengthening, and business growth efforts. Personnel selection can be seen as a decision problem and can be addressed in a multi-criteria decision-making context. This work aims to present the selection process of a barista in a Mexican coffee shop. The baristas could be the face of the company to customers, and they could significantly impact their overall experience. The personnel selection process included eleven candidates and three criteria. This process was performed using the ELECTRE-III to model the preferences of a decision-maker and RP2-NSGA-II+H, a multi-objective evolutionary algorithm that exploits fuzzy outranking relations to derive multi-criteria rankings. The ordering obtained with the algorithm did not have any inconsistency concerning the integral preference model, and it allowed for the selection of a candidate to occupy the barista position. The results show the relevance of combining preference modeling with multi-criteria analysis methods for decision-making and artificial intelligence techniques.
Realization of Extremal Spectral Data by Pentadiagonal Matrices
Authors: Pickmann-Soto Hubert , Arela-Pérez Susana , Lozano Charlie , Nina Hans
Published: July 2024

In this paper, we address the extremal inverse eigenvalue problem for pentadiagonal matrices. We provide sufficient conditions for their existence and realizability through new constructions that consider spectral data of its leading principal submatrices. Finally, we present some examples generated from the algorithmic procedures derived from our results.
Correction: Angelova et al. Estimating Surface EMG Activity of Human Upper Arm Muscles Using InterCriteria Analysis. Math. Comput. Appl. 2024, 29, 8
Authors: Angelova Silvija , Angelova Maria , Raikova Rositsa
Published: July 2024

Due to imprecise meaning in the original publication [...]
Towards Design Automation of Microfluidic Mixers: Leveraging Reinforcement Learning and Artificial Neural Networks
Authors: Chen Yuwei , Sun Taotao , Liu Zhenya , Zhang Yidan , Wang Junchao
Published: July 2024

Microfluidic mixers, a pivotal application of microfluidic technology, are primarily utilized for the rapid amalgamation of diverse samples within microscale devices. Given the intricacy of their design processes and the substantial expertise required from designers, the intelligent automation of microfluidic mixer design has garnered significant attention. This paper discusses an approach that integrates artificial neural networks (ANNs) with reinforcement learning techniques to automate the dimensional parameter design of microfluidic mixers. In this study, we selected two typical microfluidic mixer structures for testing and trained two neural network models, both highly precise and cost-efficient, as alternatives to traditional, time-consuming finite-element simulations using up to 10,000 sets of COMSOL simulation data. By defining effective state evaluation functions for the reinforcement learning agents, we utilized the trained agents to successfully validate the automated design of dimensional parameters for these mixer structures. The tests demonstrated that the first mixer model could be automatically optimized in just 0.129 s, and the second in 0.169 s, significantly reducing the time compared to manual design. The simulation results validated the potential of reinforcement learning techniques in the automated design of microfluidic mixers, offering a new solution in this field.
Transfer Learning-Based Approach for Thickness Estimation on Optical Coherence Tomography of Varicose Veins
Authors: Viqar Maryam , Madjarova Violeta , Stoykova Elena , Nikolov Dimitar , Khan Ekram , Hong Keehoon
Published: July 2024

In-depth mechanical characterization of veins is required for promising innovations of venous substitutes and for better understanding of venous diseases. Two important physical parameters of veins are shape and thickness, which are quite challenging in soft tissues. Here, we propose the method TREE (TransfeR learning-based approach for thicknEss Estimation) to predict both the segmentation map and thickness value of the veins. This model incorporates one encoder and two decoders which are trained in a special manner to facilitate transfer learning. First, an encoder–decoder pair is trained to predict segmentation maps, then this pre-trained encoder with frozen weights is paired with a second decoder that is specifically trained to predict thickness maps. This leverages the global information gained from the segmentation model to facilitate the precise learning of the thickness model. Additionally, to improve the performance we introduce a sensitive pattern detector (SPD) module which further guides the network by extracting semantic details. The swept-source optical coherence tomography (SS-OCT) is the imaging modality for saphenous varicose vein extracted from the diseased patients. To demonstrate the performance of the model, we calculated the segmentation accuracy—0.993, mean square error in thickness (pixels) estimation—2.409 and both these metrics stand out when compared with the state-of-art methods.
A Scalable, Wide-Angle Metasurface Array for Electromagnetic Energy Harvesting
Authors: Li Wenping , Shen Tao , Zhang Binzhen , Wei Yiqing
Published: July 2024

A metasurface array for electromagnetic (EM) energy harvesting for Wi-Fi bands is presented in this paper; the metasurface array consists of a metasurface unit, a rectifier, and a load resistor. Each row of unit cells in the array is interconnected to form an energy transfer channel, which enables the transfer and concentration of incident power. Furthermore, at the terminal of the channel, a single series diode rectifier circuit and a load resistor are integrated in a coplanar manner. It is used to rectify the energy in Wi-Fi bands and enables DC energy harvesting across the load. Finally, a 5 × 7 prototype of the metasurface array is fabricated and measured for the verification of the rationality of the design. Testing in an anechoic chamber shows that the prototype achieves a 72% RF-DC efficiency at 5.9 GHz when the available incident power is about 7 dBm.