bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency Shifts in Muscle Activation during Static Strength Elements on the Rings before and after an Eccentric Training Intervention in Male Gymnasts
Authors: Göpfert Beat , Schärer Christoph , Tacchelli Lisa , Gross Micah , Lüthy Fabian , Hübner Klaus
Published: March 2022

During ring performance in men’s gymnastics, static strength elements require a high level of maximal muscular strength. The aim of the study was to analyze the effect of a four-week eccentric–isokinetic training intervention in the frequency spectra of the wavelet-transformed electromyogram (EMG) during the two static strength elements, the swallow and support scale, in different time intervals during the performance. The gymnasts performed an instrumented movement analysis on the rings, once before the intervention and twice after. For both elements, the results showed a lower congruence in the correlation of the frequency spectra between the first and the last 0.5 s interval than between the first and second 0.5 s intervals, which was indicated by a shift toward the predominant frequency around the wavelet with a center frequency of 62 Hz (Wavelet W10). Furthermore, in both elements, there was a significant increase in the congruence of the frequency spectra after the intervention between the first and second 0.5 s intervals, but not between the first and last ones. In conclusion, the EMG wavelet spectra presented changes corresponding to the performance gain with the eccentric training intervention, and showed the frequency shift toward a predominant frequency due to acute muscular fatigue.
A Realistic Full-Scale 3D Modeling of Turning Using Coupled Smoothed Particle Hydrodynamics and Finite Element Method for Predicting Cutting Forces
Authors: Ojal Nishant , Copenhaver Ryan , Cherukuri Harish P. , Schmitz Tony L. , Devlugt Kyle T. , Jaycox Adam W.
Published: March 2022

Computational modelling is an effective technique for understanding the complex physics of machining. Large deformations, material separation, and high computational requirements are the key challenges faced while simulating machining. This work introduces a full-scale three-dimensional model of turning operations using a combined approach based on the Smoothed Particle Hydrodynamics (SPH) and Finite Element (FE) methods. By exploiting the advantages of each method, this approach leads to high-fidelity coupled SPH-FE machining models. Cutting forces and chip morphology are the primary results of interest. The machining models are validated with the results of turning experiments. Two-dimensional machining model underpredicts the cutting force and feed force by approximately 49% and 70%, respectively. Moreover, passive force cannot be predicted using the two-dimensional model. On the other hand, with the three-dimensional models developed in this manuscript, the difference between the total simulated force and experimentally measured force is ∼17%. The chip morphologies correlate with experiments in terms of the direction of the chip movement and the “long” continuous chips observed while turning Al 6061. This work expands the realm of machining simulations from two-dimensional orthogonal machining or sectional three-dimensional model to a full-scale realistic simulation. The encouraging simulation results show the potential to study more complex phenomena, such as machining stability and tool path modulation.
Active Electric Anomaly Detection Method for Underwater Targets Based on the Orthonormal Basis Function
Authors: Xu Yidong , Zhao Shengping , Shang Wenjing , Jia Peisong , Gao Jincheng , Korochentsev Vladimir , Grischenko Vladimir
Published: March 2022

Electric anomaly detection (EAD) has been widely used for target detection in underwater areas. However, due to the high path loss in the water, an electric anomaly is usually submerged in environmental noise and interference, which affects the detection performance of traditional anomaly detection methods. To address this problem and improve the detection accuracy in a low signal-to-noise ratio (SNR) environment, this paper proposes an active electric anomaly detection (AEAD) method based on the orthonormal basis function (OBF). First, a four-electrode active detection system was designed. Then, a set of OBFs based on the electric field disturbance model were derived to describe the detection system characteristic, linearly and effectively. Finally, an AEAD system was designed, and the proposed method was verified experimentally using a electromagnetic simulation tool to detect a spherical anomaly target. The experimental results show that, compared with the traditional AEAD methods, the proposed method has a better performance.
Local and Systemic Production of Pro-Inflammatory Eicosanoids Is Inversely Related to Sensitization to Aeroallergens in Patients with Aspirin-Exacerbated Respiratory Disease
Authors: Potaczek Daniel P. , Trąd Gabriela , Sanak Marek , Garn Holger , Mastalerz Lucyna
Published: March 2022

Aspirin-exacerbated respiratory disease (AERD) is characterized by overproduction of the pro-inflammatory eicosanoids. Although immunoglobulin E-mediated sensitization to aeroallergens is common among AERD patients, it does not belong to the defining disease characteristics. In this study of 133 AERD patients, we sought to find a relationship between sensitization to aeroallergens and local (leukotriene E4, prostaglandin E2 and prostaglandin D2) and/or systemic (leukotriene E4) production of arachidonic acid metabolites. Interestingly, a negative association between pro-inflammatory eicosanoid levels in induced sputum supernatant or urine and sensitization to aeroallergens was observed. This inverse relationship might suggest the presence of a protective effect of atopic sensitization to aeroallergens against stronger local airway inflammation and higher systemic AERD-related inflammatory activity.
Economic Valuation of Urban Green Spaces across a Socioeconomic Gradient: A South African Case Study
Authors: Lategan Louis Gerhardus , Steynberg Zene , Cilliers Elizelle Juanee , Cilliers Sarel Stephanus
Published: March 2022

Urban green spaces (UGSs) may present economic contributions through increases in proximate property values, encapsulated in the proximity principle (PP). More data on the PP is required from the Global South, where the quality and equitable distribution of UGSs are important considerations. This paper investigates the PP in Potchefstroom, South Africa following a quantitative approach, by statistically analyzing municipal property valuations in three districts differentiated according to their socioeconomic status (SES). Districts are divided into sample areas where three zones are demarcated according to their proximity to a UGS. The results show that property valuations are generally higher for properties in closer proximity to UGSs in lower- and higher-income samples, but are lower in middle-income areas. Neighborhood characteristics and SES, UGS amenity and maintenance, ecosystem services and disservices, domestic garden area and residential property size may be connected to the confirmation or rejection of the PP. The rejection of the PP in middle-income areas indicates a need to improve public UGSs as amenity destinations. The results confirming the PP in low-income areas could incentivize expenditures to improve UGS area and quality to increase the willingness to pay for proximity to such spaces and, reciprocally, increase revenue from municipal property taxes.
Spatio-Temporal Evolution and Driving Mechanism of Urbanization in Small Cities: Case Study from Guangxi
Authors: Li Lin , Zhao Kaixu , Wang Xinyu , Zhao Sidong , Liu Xingguang , Li Weiwei
Published: March 2022

Urbanization has an abundant connotation in dimensions such as population, economy, land, and society and is an important sign to measure regional economic development and social progress. The use of Night Light Data from remote sensing satellites as a proxy variable can significantly improve the accuracy and comprehensiveness of the measurement of urbanization development dynamics. Based on the Night Light Data and statistical data from 2015 to 2019, this paper quantitatively analyzes the spatio-temporal evolution pattern of urbanization in Guangxi and its driving mechanism using exploratory time-space data analysis, GeoDetector and Matrix: Boston Consulting Group, providing an important basis for sustainable urban development planning and scientific decision-making by the government. The findings show that (1) there is a high level of spatial heterogeneity and spatial autocorrelation of urbanization in Guangxi, with the Gini index of urban night light index and urban night light expansion vitality index always greater than 0.5, the global Moran’s I greater than 0.17, the spatial differentiation converging but the spatial correlation increasing. (2) The spatial pattern of urbanization in Guangxi has long been solidified, but there is a differentiation in urban development trend, with the coexistence of urban expansion and shrinkage, requiring differentiated policy design for urban governance. (3) The development and evolution of urbanization in Guangxi present a complex intertwined dynamic mechanism of action, with interaction effects of bifactor enhancement and non-linear enhancement among factors. It should be noted that the influence of factors varies greatly, with the added value of the tertiary industry, gross domestic product, total retail sales of social consumer goods having the strongest direct effect on the urban night light index, while the added value of secondary industry, per capita GDP, gross domestic product having the strongest direct effect on the urban night light expansion vitality index. All of them are key factors, followed by some significant influence factors such as government revenue, population urbanization rate, per government revenue, population urbanization rate, per capita disposable income of urban and rural residents that should not be ignored, and the rest that play indirect roles mainly by interaction.
A Three-Year Plant Study of Salt-Tolerant Transgenic Maize Showed No Effects on Soil Enzyme Activity and Nematode Community
Authors: Zeng Xing , Pei Tongtong , Song Yongfeng , Guo Pei , Zhang Huilan , Li Xin , Li Hao , Di Hong , Wang Zhenhua
Published: March 2022

The environmental effects of genetically modified crops are now a global concern. It is important to monitor the potential environmental impact of transgenic corn after commercial release. In rhizosphere soil, plant roots interact with soil enzymes and microfauna, which can be affected by the transgenes of genetically modified crops. To determine the long-term impact of transgenic plant cultivation, we conducted a field study for 3 consecutive years (2018–2020) and observed the enzyme activities and nematode populations in plots planted with transgenic maize BQ-2, non-transgenic wild-type maize (Qi319), and inbred line B73. We took soil samples from three cornfields at four different growth stages (V3, V9, R1, and R6 stages); determined soil dehydrogenase, urease, and sucrase activities; and collected and identified soil nematodes to the genus level. The results demonstrated seasonal variations in dehydrogenase, urease, and sucrase activities. However, there was a consistent trend of change. The generic composition and diversity indices of the soil nematodes did not significantly differ, although significant seasonal variation was found in the individual densities of the principal trophic groups and the diversity indices of the nematodes in all three cornfields. The results of the study suggest that a 3-year cultivation of transgenic corn had no significant effects on soil enzyme activity and the soil nematode community. This study provides a theoretical basis for the environmental impact monitoring of transgenic corn.
Research on Dynamic Performance of CRTSⅢ Type Slab Ballastless Track under Long-Term Service
Authors: Zeng Zhiping , Xiao Yancai , Wang Weidong , Huang Zhibin , Wei Wei , Houdou Saidi Boumedienne
Published: March 2022

To fill the blank in the research on the dynamic performance of track structure under long-term service, the dynamic response study of China Railway Track System Ⅲ type slab ballastless track (CRTSIII SBT) under the action of fatigue for 30 million times and the parting between track slab and self-compacting concrete (SCC) was carried out. By establishing the finite element model of the CRTSIII SBT structure and taking the stiffness change of isolation layer and fastener under fatigue state and the parting during service as the research objects, combined with the full-scale model test, the dynamic response amplitude and vibration law of track structure was analyzed based on the finite element model of axle falling test method. The results show the following: (1) Under the fatigue load, the acceleration of rail and base increases obviously, the longitudinal tensile stress of SCC surface decreases, the longitudinal tensile stress of base surface increases, and the vertical stress of each layer of track structure increases as well. (2) Under the action of the parting, the dynamic response of each structural layer increases, and the change of acceleration and stress of each layer under the action point of axle falling is the most obvious. (3) The fatigue load will weaken the vibration damping performance of the track, and the parting will continue to develop under the action of the falling axle, resulting in partial or total failure of the SCC layer. Both of them will aggravate the dynamic response of the track structure and affect driving safety, which should be paid attention to during maintenance.
Effect of Sulfate Concentration on Chloride Diffusion of Concrete under Cyclic Load
Authors: Yu Demei , Feng Chao , Fu Tengfei , Shen Aiqin
Published: March 2022

The existence of chloride ions, sulfate ions, and vehicle dynamic loads may lead to a shortened service life and premature failure of the road and bridge structures in northwestern China. Immersed in a dual-salt solution while simultaneously applying cyclic flexural loads, the free chloride ion concentration and erosion depth in concrete specimens were measured. The influence of the sulfate concentration on the apparent surface chloride concentration (Cs) and apparent diffusion coefficient (Dapp) was studied. An exponential model was used to fit the Cs, and the influence of sulfate concentration on the Cs was analyzed. The result showed that cyclic loading and solution concentration were two primary factors affecting chloride diffusion. Meanwhile, compared with the emersion conditions, dynamic loading would induce significantly accelerated chloride ion penetration. Under the coupling effect of sulfate and dynamic loading, as the sulfate concentration increased, the chloride ion concentration and erosion depth were both decreased. The existence of sulfate ions improved the chloride ion penetration resistance of concrete. The results provide insight in designing concrete in regions where multiple salt ingression (sulfate and chloride) is a major durability issue of the structures.
Multi-Steps Magnetic Flux Entrance/Exit at Thermomagnetic Avalanches in the Plates of Hard Superconductors
Authors: Chabanenko Viktor , Nabiałek Adam , Puźniak Roman
Published: March 2022

Avalanche cascades of magnetic flux have been detected at thermomagnetic instability of the critical state in the plates of Nb-Ti alloy. It was found that, the magnetic flux Φ enters conventional superconductor in screening regime and leaves in trapping regime in the form of a multistage “stairways”, with the structure dependent on the magnetic field strength and magnetic history, with approximately equal successive portions ΔΦ in temporal Φ(t) dependence, and with the width depending almost linearly on the plate thickness. The steady generation of cascades was observed for the full remagnetization cycle in the field of 2–4 T. The structure of inductive signal becomes complex already in the field of 0–2 T and it was shown, on the base of Fourier analysis, that, the avalanche flux dynamic produces, in this field range, multiple harmonics of the electric field. The physical reason of complex spectrum of the low-field avalanche dynamics can be associated with rough structure of moving flux front and with inhomogeneous relief of induction. It was established that the initiation of cascades occurs mainly in the central part of the lateral surface. The mechanism of cascades generation seems to be connected to the “resonator’s properties” of the plates.
Composites Containing Nanohydroxyapatites and a Stable TEMPO Radical: Preparation and Characterization Using Spectrophotometry, EPR and 1H MAS NMR
Authors: Byra Natalia , Krukowski Sylwester , Sadlo Jaroslaw , Kolodziejski Waclaw
Published: March 2022

Hydroxyapatite is the main constituent of mammalian hard tissues. Basic applications of synthetic hydroxyapatites include bone and dental implantology and drug delivery systems. The study of hydroxyapatite surface properties could give greater insight into the processes of bone mineralization and degradation. Nitroxide radicals are stable radicals that exhibit anticancer and antioxidative properties and are often used as spin probes to study the dynamics of complex biological systems. In this work, we attempted to adsorb the stable 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) on two hydroxyapatites (HAs) differing in specific surface area and the degree of hydration. The adsorption was carried out from cyclohexane, 1-chlorobutane and water. The solutions after adsorption were studied spectrophotometrically, while the obtained composites were characterized via NMR and EPR spectroscopy. The results show that it is possible to reproducibly obtain fairly stable composites, where the main factors influencing the adsorbed amount of the radical are solvent polarity and specific surface area of hydroxyapatite. The Langmuir isotherm was determined to be the most suitable adsorption model. The analysis of EPR and NMR spectra allowed us to determine the distribution of the TEMPO molecules on the hydroxyapatite surface, as well as a probable adsorption mechanism. The HA/TEMPO composites could potentially be used to study certain properties of hydroxyapatite surfaces with EPR spectroscopy. They could also be used as fillers after hard tissue surgery, as well as metal-free MRI contrasts.
Environmental Impact of Surgical Masks Consumption in Italy Due to COVID-19 Pandemic
Authors: Cornelio Antonella , Zanoletti Alessandra , Federici Stefania , Ciacci Luca , Depero Laura Eleonora , Bontempi Elza
Published: March 2022

The COVID-19 pandemic suddenly changed the lifestyle of billions of people. Face masks became indispensable to protect from the contagion providing a significant environmental impact. The aim of this work is to propose possible solutions to decrease masks’ impact on the environment. For this reason, different masks (surgical and fabric) were considered, and the CO2 emissions associated with the mask materials production were calculated. Carbon Footprint (CF) for each material composing the masks was evaluated through the database Ces Selector 2019. The software Qgis (version 2.18.20) allows us to elaborate the CO2 emissions maps for each Italian region. Finally, for surgical masks, which are often imported from abroad, the CF related to transport was considered. It results that fabric masks are a sustainable solution to prevent contagion. The total CO2 emission associated with the use of fabric masks from the beginning of the pandemic (March 2020) to December 2021 resulted in about 7 kton compared to 350 kton for surgical masks.
Evolution of Microstructure in Welding Heat-Affected Zone of G115 Steel with the Different Content of Boron
Authors: Chen Zhongyi , Kou Dongxu , Chen Zhengzong , Yang Fan , Ma Yonglin , Li Yiming
Published: March 2022

Welding thermal simulation was performed to investigate the effects of boron content (0, 60, and 130 ppm), welding peak temperature (Tp), and cooling time from 800 to 500 °C (t8/5) on the microstructure, carbide, subgrain, and microhardness of heat-affected zone (HAZ) in G115 steel. According to the experimental results, the microstructure of coarse-grained HAZ (CGHAZ), fine-grained HAZ (FGHAZ), inter-critical HAZ (ICHAZ), and sub-critically HAZ (SCHAZ) was martensite, martensite containing a small amount of undissolved carbide, martensite, and over-tempered martensite, tempered martensite, respectively. The presence of B element improved the thermal stability of M23C6 carbide, thereby resulting in a greater amount of undissolved carbides with a larger diameter in the materials with higher B content under the same Tp. Element B is effective in improving Ac1 and Ac3 for the material. Besides, compared with the material without and containing 60 ppm B, the Ac1 and Ac3 of the material containing 130 ppm B increased by 95 and 108 °C, 69 and 77 °C, respectively. Meanwhile, the FGHAZ area of the material containing 130 ppm B was significantly lower than the material without or containing 60 ppm B, indicating that element B can significantly reduce the formation range of FGHAZ. The alloy content in austenite of ICHAZ of materials without or containing 60 ppm B increased, compared with CGHAZ, its Ms and Mf declined by 50 and 7 °C, 46 and 7 °C, respectively. In contrast, the alloy content in austenite of the material with 130 ppm B content decreases, its Ms and Mf was 37 °C and 32 °C higher than CGHAZ, respectively. The microhardness of HAZ was ranked in descending order as CGHAZ, FGHAZ, ICHAZ, and SCHAZ. Differently, the microhardness of CGHAZ and FGHAZ showed an increasing trend with the rise of B content but exhibited a decreasing trend with the rise of t8/5.
Control of Polarization Orientation Angle of Scattered Light Based on Metasurfaces: −90° to +90° Linear Variation
Authors: Wu Song
Published: March 2022

Metasurfaces can be used to precisely control polarization state of the scattered light. Here, we present a metasurface-based terahertz device. On the one hand, it serves as a high performance linear polarization converter in transmission of over 80% power with weak reflection. It is capable of rotating linear polarization orientation angle with respect to x-axis continuously from −90° to +90° at 0.84 THz. On the other hand, it serves as a circular polarizer. It can transform a linear polarized wave into a circular polarized wave at 2.49 THz. The transmitted and reflected field are both circular polarized with 50% power. The proposed device with dual functionalities can be applied to modulate the polarization state of the signal in THz wireless communication.
Influence of Doping on the Topological Surface States of Crystalline Bi2Se3 Topological Insulators
Authors: Nowak Kamil , Jurczyszyn Michał , Chrobak Maciej , Maćkosz Krzysztof , Naumov Andrii , Olszowska Natalia , Rosmus Marcin , Miotkowski Ireneusz , Kozłowski Andrzej , Sikora Marcin , Przybylski Marek
Published: March 2022

We present STM/STS, ARPES and magnetotransport studies of the surface topography and electronic structure of pristine Bi2Se3 in comparison to Bi1.96Mg0.04Se3 and Bi1.98Fe0.02Se3. The topography images reveal a large number of complex, triangle-shaped defects at the surface. The local electronic structure of both the defected and non-defected regions is examined by STS. The defect-related states shift together with the Dirac point observed in the undefected area, suggesting that the local electronic structure at the defects is influenced by doping in the same way as the electronic structure of the undefected surface. Additional information about the electronic structure of the samples is provided by ARPES, which reveals the dependence of the bulk and surface electronic bands on doping, including such parameters as the Fermi wave vector. The subtle changes of the surface electronic structure by doping are verified with magneto-transport measurements at low temperatures (200 mK) allowing the detection of Shubnikov-de Haas (SdH) quantum oscillations.
Insights into Nanomedicine for Head and Neck Cancer Diagnosis and Treatment
Authors: Viegas Cláudia , Pereira Daniela S. M. , Fonte Pedro
Published: March 2022

Head and neck cancers rank sixth among the most common cancers today, and the survival rate has remained virtually unchanged over the past 25 years, due to late diagnosis and ineffective treatments. They have two main risk factors, tobacco and alcohol, and human papillomavirus infection is a secondary risk factor. These cancers affect areas of the body that are fundamental for the five senses. Therefore, it is necessary to treat them effectively and non-invasively as early as possible, in order to do not compromise vital functions, which is not always possible with conventional treatments (chemotherapy or radiotherapy). In this sense, nanomedicine plays a key role in the treatment and diagnosis of head and neck cancers. Nanomedicine involves using nanocarriers to deliver drugs to sites of action and reducing the necessary doses and possible side effects. The main purpose of this review is to give an overview of the applications of nanocarrier systems to the diagnosis and treatment of head and neck cancer. Herein, several types of delivery strategies, radiation enhancement, inside-out hyperthermia, and theragnostic approaches are addressed.
Recovery of Non-Ferrous Metals from PCBs Scrap by Liquation from Lead
Authors: Wędrychowicz Maciej , Piotrowicz Andrzej , Skrzekut Tomasz , Noga Piotr , Bydalek Adam
Published: March 2022

This article presents the results of research on the recycling of non-ferrous metals from PCB scrap using melting in metallic lead. The idea of this process is to dissolve (transfer) metals from PCB scrap in lead, and then liquation them by cooling the lead-metals alloy. PCB scrap was crushed and then melted into liquid lead. The lead after process was then poured into the casting mold and its chemical composition was examined. Among the various metals in the PCB scrap, copper and tin in particular are dissolved in lead. The more scrap dissolved in lead, the higher the concentration of copper and tin in the alloy. The highest obtained concentration of copper in lead were about 2.2 wt.%, and for tin about 0.8 wt.%.
Influence of 3D Printing Parameters on the Mechanical Stability of PCL Scaffolds and the Proliferation Behavior of Bone Cells
Authors: Huber Fabian , Vollmer David , Vinke Johannes , Riedel Bianca , Zankovic Sergej , Schmal Hagen , Seidenstuecker Michael
Published: March 2022

Introduction The use of scaffolds in tissue engineering is becoming increasingly important as solutions need to be found for the problem of preserving human tissue, such as bone or cartilage. In this work, scaffolds were printed from the biomaterial known as polycaprolactone (PCL) on a 3D Bioplotter. Both the external and internal geometry were varied to investigate their influence on mechanical stability and biocompatibility. Materials and Methods: An Envisiontec 3D Bioplotter was used to fabricate the scaffolds. First, square scaffolds were printed with variations in the strand width and strand spacing. Then, the filling structure was varied: either lines, waves, and honeycombs were used. This was followed by variation in the outer shape, produced as either a square, hexagon, octagon, or circle. Finally, the internal and external geometry was varied. To improve interaction with the cells, the printed PCL scaffolds were coated with type-I collagen. MG-63 cells were then cultured on the scaffolds and various tests were performed to investigate the biocompatibility of the scaffolds. Results: With increasing strand thickness and strand spacing, the compressive strengths decreased from 86.18 + 2.34 MPa (200 µm) to 46.38 + 0.52 MPa (600 µm). The circle was the outer shape with the highest compressive strength of 76.07 + 1.49 MPa, compared to the octagon, which had the lowest value of 52.96 ± 0.98 MPa. Varying the external shape (toward roundness) geometry, as well as the filling configuration, resulted in the highest values of compressive strength for the round specimens with honeycomb filling, which had a value of 91.4 + 1.4 MPa. In the biocompatibility tests, the round specimens with honeycomb filling also showed the highest cell count per mm2, with 1591 ± 239 live cells/mm2 after 10 days and the highest value in cell proliferation, but with minimal cytotoxic effects (9.19 ± 2.47% after 3 days).
Discussion on Ball Screw Slide–Roll Ratio and Entrainment Velocity Calculation
Authors: Wang Weike , Chen Shujiang , Lu Changhou , Lv Lei
Published: March 2022

The slide–roll ratio and entrainment velocity are critical parameters in ball screw mechanism tribology investigations and are often determined by Chin-Chung Wei’s approach. Their findings indicated that substantial sliding always occurs between the ball and the raceways, which appears to violate the ball drive principle. We validated Wei’s approach using the Harris method, which is widely used in rolling bearing research. When the helix angle is set to zero, significant differences occur: when the Harris method is utilized, the entrainment velocity at the inner contact points is essentially equal to that at the outer contact points, and the slide–roll ratio is zero for both; however, when Wei’s method is utilized, the entrainment velocity at the inner side is nearly three-times that of the outer side, and the slide–roll ratio at the outer side approaches two—the level of pure sliding—which is clearly incorrect. To overcome this issue, we present an accurate approach for obtaining the slide–roll ratio and entrainment velocity for ball screws by regarding the Frenet frame as a virtual cage, which is particularly applicable to those with a long lead and operating at high speeds. Moreover, we investigated the effect of structural factors on the slide–roll ratio and entrainment velocity utilizing this model.
Machine Learning Regularization Methods in High-Dimensional Monetary and Financial VARs
Authors: Sánchez García Javier , Cruz Rambaud Salvador
Published: March 2022

Vector autoregressions (VARs) and their multiple variants are standard models in economic and financial research due to their power for forecasting, data analysis and inference. These properties are a consequence of their capabilities to include multiple variables and lags which, however, turns into an exponential growth of the parameters to be estimated. This means that high-dimensional models with multiple variables and lags are difficult to estimate, leading to omitted variables, information biases and a loss of potential forecasting power. Traditionally, the existing literature has resorted to factor analysis, and specially, to Bayesian methods to overcome this situation. This paper explores the so-called machine learning regularization methods as an alternative to traditional methods of forecasting and impulse response analysis. We find that regularization structures, which allow for high dimensional models, perform better than standard Bayesian methods in nowcasting and forecasting. Moreover, impulse response analysis is robust and consistent with economic theory and evidence, and with the different regularization structures. Specifically, regarding the best regularization structure, an elementwise machine learning structure performs better in nowcasting and in computational efficiency, whilst a componentwise structure performs better in forecasting and cross-validation methods.
Geometry of Solutions of the Quasi-Vortex Filament Equation in Euclidean 3-Space E3
Authors: Hamouda Ebrahem , Moaaz Osama , Cesarano Clemente , Askar Sameh , Elsharkawy Ayman
Published: March 2022

This work aims at investigating the geometry of surfaces corresponding to the geometry of solutions of the vortex filament equation in Euclidean 3-space E3 using the quasi-frame. In particular, we discuss some geometric properties and some characterizations of parameter curves of these surfaces in E3.
Extended Beta and Gamma Matrix Functions via 2-Parameter Mittag-Leffler Matrix Function
Authors: Goyal Rahul , Agarwal Praveen , Oros Georgia Irina , Jain Shilpi
Published: March 2022

The main aim of this article is to study an extension of the Beta and Gamma matrix functions by using a two-parameter Mittag-Leffler matrix function. In particular, we investigate certain properties of these extended matrix functions such as symmetric relation, integral representations, summation relations, generating relation and functional relation.
Supporting Preservice Mathematics Teachers’ Culturally Responsive Teaching: A Focus on Teaching for Social Justice
Authors: Register Jordan , Fernandes Anthony , Pugalee David
Published: March 2022

This paper reports on how 10 middle and high school preservice teachers (PSTs) designed a social justice focused lesson using the culturally responsive mathematics teaching (CRMT) tool. Results from our analysis indicate that most of the PSTs were able to select appropriate social justice topics, though not all the PSTs integrated mathematics and social justice throughout their lessons. The results show that most of the PSTs need more experience with mathematization, handling controversial discussions, and developing transformative student action. Our work also led to a modification of the tool (CRMT-M). We discuss the implications of the study for mathematics teacher preparation.
Bayesian Nonlinear Models for Repeated Measurement Data: An Overview, Implementation, and Applications
Authors: Lee Se Yoon
Published: March 2022

Nonlinear mixed effects models have become a standard platform for analysis when data is in the form of continuous and repeated measurements of subjects from a population of interest, while temporal profiles of subjects commonly follow a nonlinear tendency. While frequentist analysis of nonlinear mixed effects models has a long history, Bayesian analysis of the models has received comparatively little attention until the late 1980s, primarily due to the time-consuming nature of Bayesian computation. Since the early 1990s, Bayesian approaches for the models began to emerge to leverage rapid developments in computing power, and have recently received significant attention due to (1) superiority to quantify the uncertainty of parameter estimation; (2) utility to incorporate prior knowledge into the models; and (3) flexibility to match exactly the increasing complexity of scientific research arising from diverse industrial and academic fields. This review article presents an overview of modeling strategies to implement Bayesian approaches for the nonlinear mixed effects models, ranging from designing a scientific question out of real-life problems to practical computations.
Knowledge of Fractions of Learners in Slovakia
Authors: Švecová Valéria , Balgová Marta , Pavlovičová Gabriela
Published: March 2022

In this research, we set two main goals: to provide empirical data that point to the knowledge of fractions among fifth-grade primary school pupils on a national scale; and to determine the level of knowledge about fractions among university students, including future primary school teachers. We used two tests—the national-wide test T5 for the fifth-graders (a research sample of approximately 45,000 pupils), and the modified fraction test based on Sfard’s theory of reification, for the university students (162 students). At the end of the study, we focused on a content analysis of the university students’ solutions. We identified persistent difficulties with concepts of fractions not only by fifth graders but also by future primary school teachers.
A Formal Analysis of Generalized Peterson’s Syllogisms Related to Graded Peterson’s Cube
Authors: Fiala Karel , Murinová Petra
Published: March 2022

This publication builds on previous publications in which we constructed syntactic proofs of fuzzy Peterson’s syllogisms related to the graded square of opposition. The aim of the publication is to be formally able to find syntactic proofs of fuzzy Peterson’s logical syllogisms with forms of fuzzy intermediate quantifiers that design the graded Peterson’s cube of opposition.
Combining Data Envelopment Analysis and Machine Learning
Authors: Guerrero Nadia M. , Aparicio Juan , Valero-Carreras Daniel
Published: March 2022

Data Envelopment Analysis (DEA) is one of the most used non-parametric techniques for technical efficiency assessment. DEA is exclusively concerned about the minimization of the empirical error, satisfying, at the same time, some shape constraints (convexity and free disposability). Unfortunately, by construction, DEA is a descriptive methodology that is not concerned about preventing overfitting. In this paper, we introduce a new methodology that allows for estimating polyhedral technologies following the Structural Risk Minimization (SRM) principle. This technique is called Data Envelopment Analysis-based Machines (DEAM). Given that the new method controls the generalization error of the model, the corresponding estimate of the technology does not suffer from overfitting. Moreover, the notion of ε-insensitivity is also introduced, generating a new and more robust definition of technical efficiency. Additionally, we show that DEAM can be seen as a machine learning-type extension of DEA, satisfying the same microeconomic postulates except for minimal extrapolation. Finally, the performance of DEAM is evaluated through simulations. We conclude that the frontier estimator derived from DEAM is better than that associated with DEA. The bias and mean squared error obtained for DEAM are smaller in all the scenarios analyzed, regardless of the number of variables and DMUs.
Theoretical and Computational Results of a Memory-Type Swelling Porous-Elastic System
Authors: Al-Mahdi Adel M. , Al-Gharabli Mohammad M. , Alahyane Mohamed
Published: March 2022

In this paper, we consider a memory-type swelling porous-elastic system. First, we use the multiplier method to prove explicit and general decay results to solutions of the system with sufficient regularities. These decay results are established under a very general assumption on the relaxation function and for suitable given data. We also perform several numerical tests to illustrate our theoretical decay results. Our results generalize and improve many earlier results in the literature.
Ulva (Enteromorpha) Polysaccharides and Oligosaccharides: A Potential Functional Food Source from Green-Tide-Forming Macroalgae
Authors: Ning Limin , Yao Zhong , Zhu Benwei
Published: March 2022

The high-valued utilization of Ulva (previously known as Enteromorpha) bioresources has drawn increasing attention due to the periodic blooms of world-wide green tide. The polysaccharide is the main functional component of Ulva and exhibits various physiological activities. The Ulva oligosaccharide as the degradation product of polysaccharide not only possesses some obvious activities, but also possesses excellent solubility and bioavailability. Both Ulva polysaccharides and oligosaccharides hold promising potential in the food industry as new functional foods or food additives. Studies on Ulva polysaccharides and oligosaccharides are increasing and have been the focus of the marine bioresources field. However, the comprehensive review of this topic is still rare and do not cover the recent advances of the structure, isolation, preparation, activity and applications of Ulva polysaccharides and oligosaccharides. This review systematically summarizes and discusses the recent advances of chemical composition, extraction, purification, structure, and activity of Ulva polysaccharides as well as oligosaccharides. In addition, the potential applications as new functional food and food additives have also been considered, and these will definitely expand the applications of Ulva oligosaccharides in the food and medical fields.
The Effect of Glucose Metabolism and Breastfeeding on the Intestinal Microbiota of Newborns of Women with Gestational Diabetes Mellitus
Authors: Jovandaric Miljana Z. , Milenkovic Svetlana J. , Babovic Ivana R. , Babic Sandra , Dotlic Jelena
Published: March 2022

Gestational diabetes mellitus (GDM) is a pregnancy complication in which women without previously diagnosed diabetes develop chronic hyperglycemia during gestation. The diet and lifestyle of the mother during pregnancy as well as lactation have long-term effects on the child’s health and development. Detection of early risk markers of adult-age chronic diseases that begin during prenatal life and the application of complex nutritional interventions at the right time may reduce the risk of these diseases. Newborns adapt to the ectopic environment by developing intestinal immune homeostasis. Adequate initial colonization of bacteria is necessary for sufficient development of intestinal immunity. The environmental determinant of adequate colonization is breast milk. Although a developing newborn is capable of producing an immune response, the effector immune component requires bacterial stimulation. Breast milk stimulates the proliferation of a well-balanced and diverse microbiota, which initially influences the switch from an intrauterine TH2 predominant to a TH1/TH2 balanced response and the activation of T-regulatory cells by breast milk-stimulated specific organisms (Bifidobacteria, Lactobacillus, and Bacteroides). Breastfeeding in newborns of mothers with diabetes mellitus regulates the adequate immune response of the newborn and prevents diseases of the neonatal and postnatal period.
The Key Role of Hepcidin-25 in Anemia in Multiple Myeloma Patients with Renal Impairment
Authors: Banaszkiewicz Małgorzata , Małyszko Jolanta , Batko Krzysztof , Koc-Żórawska Ewa , Żórawski Marcin , Dumnicka Paulina , Jurczyszyn Artur , Woziwodzka Karolina , Maleszka Aleksandra , Krzanowski Marcin , Kraśniak Andrzej , Drożdż Ryszard , Krzanowska Katarzyna
Published: March 2022

Background and objectives: Anemia is common in multiple myeloma (MM) and is caused by a complex pathomechanism, including impaired iron homeostasis. Our aim is to evaluate the biomarkers of iron turnover: serum soluble transferrin receptor (sTfR) and hepcidin-25 in patients at various stages of MM in relation with markers of anemia, iron status, inflammation, renal impairment and burden of the disease and as predictors of mortality. Materials and methods: Seventy-three MM patients (six with smoldering and 67 with symptomatic disease) were recruited and observed for up to 27 months. Control group included 21 healthy individuals. Serum sTfR and hepcidin were measured with immunoenzymatic assays. Results: MM patients with and without anemia had higher sTFR compared to controls, while only anemic patients had higher hepcidin-25. Both hepcidin-25 and sTfR were higher in anemic than non-anemic patients. Higher hepcidin-25 (but not sTfR) was associated with increasing MM advancement (from smoldering to International Staging System stage III disease) and with poor response to MM treatment, which was accompanied by lower blood hemoglobin and increased anisocytosis. Neither serum hepcidin-25 nor sTfR were correlated with markers of renal impairment. Hepcidin-25 predicted blood hemoglobin in MM patients independently of other predictors, including markers of renal impairment, inflammation and MM burden. Moreover, both blood hemoglobin and serum hepcidin-25 were independently associated with patients’ 2-year survival. Conclusions: Our results suggest that hepcidin-25 is involved in anemia in MM and its concentrations are not affected by kidney impairment. Moreover, serum hepcidin-25 may be an early predictor of survival in this disease, independent of hemoglobin concentration. It should be further evaluated whether including hepcidin improves the early diagnosis of anemia in MM.
Effect of the Peptization Process and Thermal Treatment on the Sol-Gel Preparation of Mesoporous α-Alumina Membranes
Authors: Naseer Danyal , Ha Jang-Hoon , Lee Jongman , Park Chanhyuk , Song In-Hyuck
Published: March 2022

Compared to traditional membrane materials, alumina membranes are particularly beneficial for industrial wastewater treatment. However, the development of mesoporous α-alumina membranes for ultrafiltration applications is still a challenge due to uncontrolled pore size. In this study, we optimized the sol-gel method for the fabrication of a high-performance mesoporous α-alumina membrane. The peptization conditions (pH and peptization time) and phase transformation of boehmite were investigated to achieve better properties of the α-alumina membrane. The surface properties of the membrane were observed to be improved by reducing the system pH to 3.5 and increasing the peptization time to 24 h. The effect of sintering temperature on the phase transformation behavior, microstructures and performance of the membranes was also elucidated. An α-alumina ultrafiltration membrane with an average thickness of 2 μm was obtained after sintering at 1100 °C. The molecular weight cut-off of the α-alumina membrane, as obtained by the filtration of aqueous PEG solution, was approximately 163 kDa (12.5 nm). This is the smallest pore size ever reported for pure α-alumina membranes.
Green LD (BOF) Steelmaking—Reduced CO2 Emissions via Increased Scrap Rate
Authors: Voraberger Bernhard , Wimmer Gerald , Dieguez Salgado Uxia , Wimmer Erich , Pastucha Krzysztof , Fleischanderl Alexander
Published: March 2022

The basic oxygen furnace (BOF) is the dominating primary steelmaking process. It is an autothermal process where hot metal and scrap are used as charging materials. The decarbonization and transformation of integrated BOF steelmaking will be the most important challenge in the coming years. Steel scrap is a charge material without new CO2 emissions, whose availability is expected to grow significantly and will play a key role in this decarbonization process. Several solutions have been developed by Primetals Technologies to provide additional energy for processing higher scrap rates in integrated BOF steelmaking. Such solutions include simple upgrade packages installed on existing converters such as process models for heat optimization, post-combustion, and scrap preheating lances. For higher scrap rates from 30% to 50%, a combination blowing converter and JET converter is required to provide sufficient mixing during scrap melting and the highest heat transfer from the increased post-combustion. Hybrid EAF–BOF operation and limitations regarding scrap quality also need to be considered for the transformation of steelmaking. Scrap sorting and processing can be a solution to reduce residual levels in crude steel for high scrap rates. Based on reference plant data, the CO2 reduction potential of the presented solution versus the effort and complexity of implementation is compared.
Wear Resistance of FeCrAlNbNi Alloyed Zone via Laser Surface Alloying on 304 Stainless Steel
Authors: Cui Chunsheng , Nie Jinhao , Li Yuxin , Guan Qingfeng , Cai Jie , Zhang Pengfei , Wu Jie
Published: March 2022

In order to enhance the wear resistance of 304 stainless steel, a FeCrAlNbNi alloyed zone (AZ) was deposited on its surface using laser surface alloying technology, and the wear resistance of the AZ was investigated. The results found that the AZ had a dense and fine structure and no obvious defects, and the microstructure was mainly composed of equiaxed dendrites. A large amount of iron compounds and iron-based solid solutions in the AZ made the average microhardness of the AZ about 2.6 times higher than of the substrate. The friction and wear performance of the AZ at 25 °C, 200 °C, 400 °C and 600 °C better than that of the substrate. As far as the AZ was concerned, the abrasion resistance was the best under normal temperature environment. At 200 °C and 400 °C, due to the repeated extrusion and grinding of the friction pair, the oxide layer formed on the AZ surface was prone to microcracks and peeling off, which reduces the wear resistance. Especially at 400 °C, the formation and peeling speed of the oxide layer is accelerated, and the wear resistance is the lowest. However, when the temperature reached 600 °C, an Al2O3 layer was formed. And the Al2O3 has greater wear resistance to protect the AZ. At this time, the wear resistance was greatly improved compared to 200 °C and 400 °C. Therefore, as the temperature increased, the wear resistance of the AZ first decreased and then increased.