bluuebunny/crossref_metadata_2025 huggingface dataset:
Targeted Next-Generation Sequencing for the Identification of Genetic Predictors of Radiation-Induced Late Skin Toxicity in Breast Cancer Patients: A Preliminary Study
Authors: Cargnin Sarah , Barizzone Nadia , Basagni Chiara , Pisani Carla , Ferrara Eleonora , Masini Laura , D’Alfonso Sandra , Krengli Marco , Terrazzino Salvatore
Published: September 2021

Normal tissue radiosensitivity is thought to be influenced by an individual’s genetic background. However, the specific genetic variants underlying the risk of late skin reactions following radiotherapy for breast cancer remain elusive. To unravel the genetic basis for radiation-induced late skin toxicity, we carried out targeted next-generation sequencing of germline DNA samples from 48 breast cancer patients with extreme late skin toxicity phenotypes, consisting of 24 cases with grade 2–3 subcutaneous fibrosis and/or grade 2–3 telangiectasia (LENT-SOMA scales) and 24 controls with grade 0 fibrosis and grade 0 telangiectasia. In this exploratory study, a total of five single-nucleotide variants (SNVs) located in three genes (TP53, ERCC2, and LIG1) reached nominal levels of statistical significance (p < 0.05). In the replication study, which consisted of an additional 45 cases and 192 controls, none of the SNVs identified by targeted NGS achieved nominal replication. Nevertheless, TP53 rs1042522 (G > C, Pro72Arg) in the replication cohort had an effect (OR per C allele: 1.52, 95%CI: 0.82–2.83, p = 0.186) in the same direction as in the exploratory cohort (OR per C allele: 4.70, 95%CI: 1.51–14.6, p = 0.007) and was found be nominally associated to the risk of radiation-induced late skin toxicity in the overall combined cohort (OR per C allele: 1.79, 95%CI: 1.06–3.02, p = 0.028). These results raise the possibility of an association between TP53 rs1042522 and risk of radiation-induced late skin toxicity in breast cancer patients; however, large replication studies are warranted for conclusive evidence.
Analyst Forecasts during the COVID-19 Pandemic: Evidence from REITs
Authors: Anglin Paul , Cui Jianxin , Gao Yanmin , Zhang Li
Published: September 2021

The COVID-19 pandemic disrupts capital markets and confuses decision makers. This event represents an opportunity to better understand how financial analysts forecast earnings. We focus on forecasts for Real Estate Investment Trusts (REITs) in the United States, since REITs are relatively transparent during normal times, and since the real estate sector, as a whole, displays wide variations in forecasts during the pandemic. Using data between October 2018 and November 2020, our regression analysis finds that the severity of the pandemic increases analysts’ forecast error and dispersion. Government interventions have an offsetting effect, which is relevant during the more severe times. These results are robust to various measures of the severity of the pandemic. We also find that the pandemic has differential effects across property types, where forecast error rises by more, for REITs, when focusing on Hospitality and Industrial properties, and dispersion rises by more, for REITs, when focusing on Hospitality, Retail, and Technology properties.
Integrated Production and Transportation Scheduling in E-Commerce Supply Chain with Carbon Emission Constraints
Authors: Wang Weixin , Wang Shizhen , Su Jiafu
Published: September 2021

Carbon emission constraints and trading policies in e-commerce environments have brought huge challenges to the operation of supply chain enterprises. In order to ensure the good operation of the e-commerce supply chain in a low-carbon environment, a supply chain scheduling optimization method based on integration of production and transportation with carbon emission constraints is proposed; we use it to analyze the impact of centralized decision-making mode and decentralized decision-making mode on supply chain scheduling and establish a scheduling optimization model that aims at optimal carbon emissions and costs. A multilevel genetic algorithm was designed according to the characteristics of the model, and numerical examples are used to verify the effectiveness of the model and algorithm. The results show that the centralized decision-making mode plays the role of the carbon emission constraints to the greatest extent; the carbon emissions and the cost are smallest in the centralized decision-making mode. The decentralized decision-making mode leads to the overall cost preference of the supply chain due to separate decisions made by enterprises, and the carbon emissions in the supply chain are greater. Transportation experts, business managers and government departments are interesting for integrated production and transportation scheduling in e-commerce supply chain with carbon emission constraints. Further research should address integrated production and transportation scheduling in dual-channel low supply chains.
Land Use Multi-Suitability, Land Resource Scarcity and Diversity of Human Needs: A New Framework for Land Use Conflict Identification
Authors: Dong Guanglong , Ge Yibing , Jia Haiwei , Sun Chuanzhun , Pan Senyuan
Published: September 2021

Land use conflicts are intensifying due to the rapid urbanization and accelerated transformation of social and economic development. Accurate identification of land use conflicts is an important prerequisite for resolving land use conflicts and optimizing the spatial pattern of land use. Previous studies on land use conflict using multi-objective evaluation methods mainly focused on the suitability or competitiveness of land use, ignoring land resource scarcity and the diversity of human needs, hence reducing the accuracy of land use conflict identification. This paper proposes a new framework for land use conflict identification. Considering land use multi-suitability, land resource scarcity and the diversity of human needs, the corresponding evaluation index system was constructed, respectively, and the linear weighted sum model was used to calculate the land use conflict index. Taking Jinan as the study area, the spatial distribution characteristics of land use conflicts are accurately identified and analyzed. The results show that: (1) Land use multi-suitability in Shanghe county and Jiyang district is high, but the intensity of land use conflict is not. This indicates that land use multi-suitability is the premise and basis of land use conflict, but it is not the only determinant, which is consistent with our hypothesis. (2) Land use conflicts in Jinan were dominant by medium conflict, accounting for 43.89% of the conflicts, while strong and weak land use conflicts accounted for 25.21% and 30.90% of the conflicts, respectively. The spatial distribution of land use conflicts is obviously different, with high conflicts in the north and low conflicts in the south. Strong land use conflicts are concentrated in the urban and rural transition zones of Tianqiao, Huaiyin and Shizhong districts and in the northern parts of Licheng and Zhangqiu districts. (3) Inefficient land use and land resource waste aggravated regional land use conflicts in Licheng and Zhangqiu districts. (4) The new framework for land use conflict identification proposed in this study can accurately identify land use conflicts, providing a scientific reference and new ideas for accurate identification of land use conflicts.
Evolutionary Optimization of Machining Parameters Based on Surface Roughness in End Milling of Hot Rolled Steel
Authors: Abu-Mahfouz Issam , Banerjee Amit , Rahman Esfakur
Published: September 2021

Surface roughness measurements of machined parts are usually performed off-line after the completion of the machining operation. The objective of this work is to develop a surface roughness prediction method based on the processing of vibration signals during steel end milling operation performed on a vertical CNC machining center. The milling cuts were run under varying conditions (such as the spindle speed, feed rate, and depth of cut). This is a first step in the attempt to develop an online milling process monitoring system. The study presented here involves the analysis of vibration signals using statistical time parameters, frequency spectrum, and time-frequency wavelet decomposition. The analysis resulted in the extraction of 245 features that were used in the evolutionary optimization study to determine optimal cutting conditions based on the measured surface roughness of the milled specimen. Three feature selection methods were used to reduce the extracted feature set to smaller subsets, followed by binarization using two binarization methods. Three evolutionary algorithms—a genetic algorithm, particle swarm optimization and two variants, differential evolution and one of its variants, have been used to identify features that relate to the “best” surface finish measurements. These optimal features can then be related to cutting conditions (cutting speed, feed rate, and axial depth of cut). It is shown that the differential evolution and its variant performed better than the particle swarm optimization and its variants, and both differential evolution and particle swarm optimization perform better than the canonical genetic algorithm. Significant differences are found in the feature selection methods too, but no difference in performance was found between the two binarization methods.
Preparation of Crystalline LaFeO3 Nanoparticles at Low Calcination Temperature: Precursor and Synthesis Parameter Effects
Authors: Jiang Wen , Cheng Liwei , Gao Jianghui , Zhang Shiyu , Wang Hao , Jin Zhihao , Tang Zhongfeng , Peng Cheng
Published: September 2021

Substantial effort has been devoted to fabricating nanocrystalline lanthanum ferrite (LaFeO3), and calcination is the crucial process of crystallization in both high-temperature strategies and wet chemical methods. Lowering the calcination temperature gives the ability to resist the growth and agglomeration of nanoparticles, therefore contributing to preserve their unique nanostructures and properties. In this work, we prepared crystalline LaFeO3 nanoparticles with a calcination process at 500 °C, lower than the calcination temperature required in most wet chemistry methods. Correspondingly, the experimental conditions, including stoichiometric ratios, pH values, precipitants, complexant regent, and the calcination temperatures, were investigated. We found that the crystalline LaFeO3 was formed with crystalline NaFeO2 after calcination at 500 °C. Furthermore, the structure of FeO6 octahedra that formed in coprecipitation was associated with the process of crystallization, which was predominantly determined by calcination temperature. Moreover, an illusion of pure-phase LaFeO3 was observed when investigated by X-ray diffraction spectroscopy, which involves amorphous sodium ferrite or potassium ferrite, respectively. These findings can help prepare nanostructured perovskite oxides at low calcination temperatures.
Electron Beam Melting of Niobium Alloys from Blended Powders
Authors: Hankwitz Jameson P. , Ledford Christopher , Rock Christopher , O’Dell Scott , Horn Timothy J.
Published: September 2021

Niobium-based tungsten alloys are desirable for high-temperature structural applications yet are restricted in practice by limited room-temperature ductility and fabricability. Powder bed fusion additive manufacturing is one technology that could be leveraged to process alloys with limited ductility, without the need for pre-alloying. A custom electron beam powder bed fusion machine was used to demonstrate the processability of blended Nb-1Zr, Nb-10W-1Zr-0.1C, and Nb-20W-1Zr-0.1C powders, with resulting solid optical densities of 99+%. Ultimately, post-processing heat treatments were required to increase tungsten diffusion in niobium, as well as to attain satisfactory mechanical properties.
Near-Infrared Femtosecond Laser Ablation of Au-Coated Ni: Effect of Organic Fluids and Water on Crater Morphology, Ablation Efficiency and Hydrodynamic Properties of NiAu Nanoparticles
Authors: Lasemi Niusha , Rupprechter Günther , Liedl Gerhard , Eder Dominik
Published: September 2021

Scanning electron microscopy (SEM) and profilometry of the crater morphology and ablation efficiency upon femtosecond laser ablation of Au-coated Ni targets in various fluids revealed a pronounced dependence on the ablation medium. For ethanol, a sufficient ablation efficiency was obtained, whereas for 2-butanol a higher efficiency indicated stronger laser–target interaction. Hierarchical features in the crater periphery pointed to asymmetrical energy deposition or a residual effect of the Coulomb-explosion-initiating ablation. Significant beam deviation in 2-butanol caused maximum multiple scattering at the crater bottom. The highest values of microstrain and increased grain size, obtained from Williamson–Hall plots, indicated the superposition of mechanical stress, defect formation and propagation of fatigue cracks in the crater circumference. For n-hexane, deposition of frozen droplets in the outer crater region suggested a femtosecond-laser-induced phase explosion. A maximum ablation depth occurred in water, likely due to its high cooling efficiency. Grazing incidence micro X-ray diffraction (GIXRD) of the used target showed residual carbon and partial surface oxidation. The produced nanoparticle colloids were examined by multiangle dynamic light scattering (DLS), employing larger scattering angles for higher sensitivity toward smaller nanoparticles. The smallest nanoparticles were obtained in 2-butanol and ethanol. In n-hexane, floating carbon flakes originated from femtosecond-laser-induced solvent decomposition.
Experimental Study on a Microwave Composite Forming Process Based on a SiC Mold for Manufacturing Fiber Metal Laminate
Authors: Park Eu-Tteum , Kim Jeong , Kang Beom-Soo , Song Woojin
Published: September 2021

The microwave composite forming (MCF) process can reduce manufacturing cost because the process time is reduced by the dielectric heating of the mold and the composite material. In a previous study, the MCF process using a commercial microwave oven with a polytetrafluoroethylene mold was applied. Disadvantages of the previous MCF process have been investigated. These included the difference in tensile properties according to the cutting location, absence of a method to measure temperature during the MCF process, and the fact that the input power cannot be controlled according to the temperature. To solve these problems, a microwave oven with a silicon carbide mold was proposed in this study. Uniaxial tensile tests were conducted to obtain the tensile properties of the fiber metal laminate (FML) specimen. In addition, a microscopic image was captured to investigate the non-adhesive area. The tensile properties and thickness distribution of the FML specimens manufactured by the proposed and previous MCF processes were compared according to the cutting location of the FML sheets. Furthermore, the non-adhesive area was quantified to compare the processes. The results revealed that the proposed MCF process improved the tensile properties of the FML specimen and reduced the non-adhesive area.
Polysaccharide-Based Nanocomposites for Food Packaging Applications
Authors: Pal Kunal , Sarkar Preetam , Anis Arfat , Wiszumirska Karolina , Jarzębski Maciej
Published: September 2021

The article presents a review of the literature on the use of polysaccharide bionanocomposites in the context of their potential use as food packaging materials. Composites of this type consist of at least two phases, of which the outer phase is a polysaccharide, and the inner phase (dispersed phase) is an enhancing agent with a particle size of 1–100 nm in at least one dimension. The literature review was carried out using data from the Web of Science database using VosViewer, free software for scientometric analysis. Source analysis concluded that polysaccharides such as chitosan, cellulose, and starch are widely used in food packaging applications, as are reinforcing agents such as silver nanoparticles and cellulose nanostructures (e.g., cellulose nanocrystals and nanocellulose). The addition of reinforcing agents improves the thermal and mechanical stability of the polysaccharide films and nanocomposites. Here we highlighted the nanocomposites containing silver nanoparticles, which exhibited antimicrobial properties. Finally, it can be concluded that polysaccharide-based nanocomposites have sufficient properties to be tested as food packaging materials in a wide spectrum of applications.
High-Performance Washable PM2.5 Filter Fabricated with Laser-Induced Graphene
Authors: Nguyen Anh-Phan , Kang Won-Kyu , Lee Jung-Bae , In Jung-Bin
Published: September 2021

This study demonstrates a novel application of laser-induced graphene (LIG) as a reusable conductive particulate matter (PM) filter. Four types of LIG-based filters were fabricated based on the laser-induced pyrolysis of thin polyimide (PI) sheets, each pyrolyzed on either a single side or both sides, with or without densification. The LIG filters exhibited a high removal efficiency while maintaining minimal pressure drop compared to a commercial fiberglass filter. The densified LIG (dLIG) filters displayed a higher PM2.5 removal efficiency (>99.86%) than regular LIG filters. The dLIG filters also exhibited excellent durability when tested for washability by ultrasonication in tap water. After being cleaned and left to dry, the structures of the dLIG filters were well-maintained; their filtration efficiencies were also well-maintained (less than a 7% change in PM2.5 removal efficiency), and their resistances only marginally increased (less than a 7% increase after five uses). These results demonstrate the robustness and reusability of the dLIG filters and the accessibility of their cleaning (not requiring aggressive cleaning agents). These promising features will enable the application of LIG in economical, scalable, and high-performance air cleaning.
Structure Life Extension towards the Structural Integrity of Sukhoi Su-30MKM
Authors: Venugopal Arvinthan , Mohammad Roslina , Koslan Md Fuad Shah , Shafie Ashaari , Ali Alizarin , Eugene Owi
Published: September 2021

The airframe structures of most fighter aircraft in the Royal Malaysian Airforce have been in service for 10 to 20 years. The effect of fatigue loading, operating conditions, and environmental degradation has led to the structural integrity of the airframe being assessed for its airworthiness. Various NDT methods were used to determine the current condition of the aircraft structure after operation of beyond 10 years, and their outcomes are summarized. In addition, although there are six critical locations, the wing root was chosen since it has the highest possibility of fatigue failure. It was further analyzed using simulation analysis for fatigue life. This contributes to the development of the maintenance task card and ultimately assists in extending the service life of the fighter aircraft. Using the concept of either safe life or damage tolerance as its fatigue design philosophy, the RMAF has adopted the Aircraft Structural Integrity Program (ASIP) to monitor the structural integrity of its fighter aircraft. With the current budget constraints and structural life extension requirements, the RMAF has embarked on the non-destructive testing method and engineering analysis. The research outcome will enhance the ASIP for other aircraft platforms in the RMAF fleet for its structure life assessment or service life extension program.
A Combined Experimental and Modeling Study for Pellet-Fed Extrusion-Based Additive Manufacturing to Evaluate the Impact of the Melting Efficiency
Authors: La Gala Andrea , Fiorio Rudinei , Ceretti Daniel V. A. , Erkoç Mustafa , Cardon Ludwig , D’hooge Dagmar R.
Published: September 2021

To improve the product quality of polymeric parts realized through extrusion-based additive manufacturing (EAM) utilizing pellets, a good control of the melting is required. In the present work, we demonstrate the strength of a previously developed melt removal using a drag framework to support such improvement. This model, downscaled from conventional extrusion, is successfully validated for pellet-based EAM—hence, micro-extrusion—employing three material types with different measured rheological behavior, i.e., acrylonitrile-butadiene-styrene (ABS), polylactic acid (PLA) and styrene-ethylene-butylene-styrene polymer (SEBS). The model’s validation is made possible by conducting for the first time dedicated EAM screw-freezing experiments combined with appropriate image/data analysis and inputting rheological data. It is showcased that the (overall) processing temperature is crucial to enable similar melting efficiencies. The melting mechanism can vary with the material type. For ABS, an initially large contribution of viscous heat dissipation is observed, while for PLA and SEBS thermal conduction is always more relevant. It is highlighted based on scanning electron microscopy (SEM) analysis that upon properly tuning the finalization of the melting point within the envisaged melting zone, better final material properties are achieved. The model can be further used to find an optimal balance between processing time (e.g., by variation of the screw frequency) and material product performance (e.g., strength of the printed polymeric part).
Carrageenan as an Ecological Alternative of Polyvinylidene Difluoride Binder for Li-S Batteries
Authors: Kazda Tomáš , Capková Dominika , Jaššo Kamil , Fedorková Straková Andrea , Shembel Elena , Markevich Alex , Sedlaříková Marie
Published: September 2021

Lithium-sulfur batteries are one of the most promising battery systems nowadays. However, this system is still not suitable for practical application because of the number of shortcomings that limit its cycle life. One of the main problems related to this system is the volumetric change during cycling. This deficiency can be compensated by using the appropriate binder. In this article, we present the influence of a water-soluble binder carrageenan on the electrochemical properties of the Li-S battery. The electrode with a carrageenan binder provides good stability during cycling and at high C-rates. Electrochemical testing was also carried out with a small prototype pouch cell with a capacity of 16 mAh. This prototype pouch cell with the water-based carrageenan binder showed lower self-discharge and low capacity drop. Capacity decreased by 7% after 70 cycles.
Dissimilar Laser Welding of Austenitic Stainless Steel and Abrasion-Resistant Steel: Microstructural Evolution and Mechanical Properties Enhanced by Post-Weld Heat Treatment
Authors: Hietala Mikko , Jaskari Matias , Ali Mohammed , Järvenpää Antti , Hamada Atef
Published: September 2021

In this study, ultra-high-strength steels, namely, cold-hardened austenitic stainless steel AISI 301 and martensitic abrasion-resistant steel AR600, as base metals (BMs) were butt-welded using a disk laser to evaluate the microstructure, mechanical properties, and effect of post-weld heat treatment (PWHT) at 250 °C of the dissimilar joints. The welding processes were conducted at different energy inputs (EIs; 50–320 J/mm). The microstructural evolution of the fusion zones (FZ) in the welded joints was examined using electron backscattering diffraction (EBSD) and laser scanning confocal microscopy. The hardness profiles across the weldments and tensile properties of the as-welded joints and the corresponding PWHT joints were measured using a microhardness tester and universal material testing equipment. The EBSD results showed that the microstructures of the welded joints were relatively similar since the microstructure of the FZ was composed of a lath martensite matrix with a small fraction of austenite. The welded structure exhibited significantly higher microhardness at the lower EIs of 50 and 100 J/mm (640 HV). However, tempered martensite was promoted at the high EI of 320 J/mm, significantly reducing the hardness of the FZ to 520 HV. The mechanical tensile properties were considerably affected by the EI of the as-welded joints. Moreover, the PWHT enhanced the tensile properties by increasing the deformation capacity due to promoting the tempered martensite in the FZ.
Opportunities, Challenges and Prospects for Electrodeposition of Thin-Film Functional Layers in Solid Oxide Fuel Cell Technology
Authors: Kalinina Elena , Pikalova Elena
Published: September 2021

Electrolytic deposition (ELD) and electrophoretic deposition (EPD) are relevant methods for creating functional layers of solid oxide fuel cells (SOFCs). This review discusses challenges, new findings and prospects for the implementation of these methods, with the main emphasis placed on the use of the ELD method. Topical issues concerning the formation of highly active SOFC electrodes using ELD, namely, the electrochemical introduction of metal cations into a porous electrode backbone, the formation of composite electrodes, and the electrochemical synthesis of perovskite-like electrode materials are considered. The review presents examples of the ELD formation of the composite electrodes based on porous platinum and silver, which retain high catalytic activity when used in the low-temperature range (400–650 °C). The features of the ELD/EPD co-deposition in the creation of nanostructured electrode layers comprising metal cations, ceramic nanoparticles, and carbon nanotubes, and the use of EPD to create oriented structures are also discussed. A separate subsection is devoted to the electrodeposition of CeO2-based film structures for barrier, protective and catalytic layers using cathodic and anodic ELD, as well as to the main research directions associated with the deposition of the SOFC electrolyte layers using the EPD method.
Self-Lubricating Materials for Extreme Condition Applications
Authors: John Merbin , Menezes Pradeep L.
Published: September 2021

Lubrication for extreme conditions, such as high temperature, cryogenic temperature, vacuum pressure, high load, high speed, and corrosive environments, is a continuing challenge among tribologists and space engineers due to the inadequate friction and wear properties of liquid lubricants. As a result, tremendous research effort has been put forward to study lubrication mechanisms for various machine elements under challenging conditions over the past two decades. Self-lubricating materials have been most widely used for adequate lubrication in extreme conditions in recent years. This review paper presents state-of-the-art of materials for lubrication in extreme condition applications in aerospace, automotive, and power generation areas. More specifically, solid lubricants dispersed in various matrices for lubrication application were analyzed in-depth under challenging conditions. This study also reports the self-lubricating materials and their lubrication mechanisms. Finally, various applications and challenges of self-lubricating materials were explored.
Comparison of the Values of Solar Cell Contact Resistivity Measured with the Transmission Line Method (TLM) and the Potential Difference (PD)
Authors: Musztyfaga-Staszuk Małgorzata
Published: September 2021

This work presents a comparison of values of the contact resistivity of silicon solar cells obtained using the following methods: the transmission line model method (TLM) and the potential difference method (PD). Investigations were performed with two independent scientific units. The samples were manufactured with silver front electrodes. The co-firing process was performed in an infrared belt furnace in a temperature range of 840 to 960 °C. The electrical properties of a batch of solar cells fabricated in two cycles were investigated. This work focuses on the different metallisation temperatures of co-firing solar cells and measurements were carried out using the methods mentioned. In the TLM and PD methods, the same calculation formulae were used. Moreover, solar cell parameters measured with these methods had the same, similar, or sometimes different but strongly correlated values. Based on an analysis of the selected databases, this article diagnoses the recent and current state of knowledge regarding the employment of the TLM and PD methods and the available hardware base. These methods are of interest to various research centres, groups of specialists dealing with the optimisation of the electrical properties of silicon photovoltaic cells, and designers of measuring instruments.
Porosity of Calcium Silicate Hydrates Synthesized from Natural Rocks
Authors: Siauciunas Raimundas , Smalakys Giedrius , Dambrauskas Tadas
Published: September 2021

In this work, the suitability of natural raw materials with various modifications of SiO2—granite sawing waste (quartz) and opoka (a mixture of cristobalite, tridymite, quartz, and an amorphous part)—for the 1.13 nm tobermorite and xonotlite synthesis is examined, and their specific surface area, pore diameter and volume, and the predominant pores are determined. Hydrothermal syntheses were carried out at 200 °C for 12 and 72 h from mixtures with a molar ratio of CaO/SiO2 = 1.0. X-ray diffraction analysis, simultaneous thermal analysis, and scanning electronic microscopy were used, which showed that in the lime–calcined opoka mixture the formation of crystalline calcium silicate hydrates takes place much faster than in the lime–granite sawing waste mixture. The high reactivity of amorphous SiO2 results in the rapid formation of 1.13 nm tobermorite and xonotlite (12 h). According to Brunauer, Emmet and Taller (BET) analysis data, this product features a specific surface area of ~68 m2/g, a total pore volume of 245 × 10−3 cm3/g, and has dominating 1–2.5 nm and 5–20 nm diameter pores. This porosity of the material should provide good thermal insulation properties of the products made from it as no air convection occurs in the fine pores.
Inconel 625/AISI 413 Stainless Steel Functionally Graded Material Produced by Direct Laser Deposition
Authors: Ferreira André Alves , Emadinia Omid , Cruz João Manuel , Reis Ana Rosanete , Vieira Manuel Fernando
Published: September 2021

Functionally graded material (FGM) based on Inconel 625 and AISI 431 stainless steel powders was produced by applying the direct laser deposition (DLD) process. The FGM starts with layers of Inconel 625 and ends with layers of 431 stainless steel having three intermediate zones with the composition (100-X)% Inconel 625-X% 431 stainless steel, X = 25, 50, and 75, in that order. This FGM was deposited on a 42CrMo4 steel substrate, with and without preheating. Microstructures of these FGMs were evaluated, while considering the distribution of chemical composition and grain structure. Microstructures mainly consisted of columnar grains independent of preheating condition; epitaxial growth was observed. The application of a non-preheated substrate caused the formation of planar grains in the vicinity of the substrate. In addition, hardness maps were produced. The hardness distribution across these FGMs confirmed a smooth transition between deposited layers; however, the heat-affected zone was greatly influenced by the preheating condition. This study suggests that an optimum Inconel 625/AISI 431 FGM obtained by DLD should not exceed 50% AISI 431 stainless steel.
Continuous, Large-Scale, and High Proportion of Bioinspired Phosphogypsum Composites via Reactive Extrusion
Authors: Ran Jingyu , Su Xiangdong , Zhang Jiangang , Zhang Jie , Chen Jiajun , Liu Kun , Liu Zhao , Hu Yi , Sun Liqun , Jiang Deyong
Published: September 2021

Biological matter evolution provides an idea for the human design and synthesis of new materials. However, biomimetic materials only stay in laboratory-scale models, and their large-scale industrial applications are yet to be realized. Here, inspired by nacre’s architecture, we report a continuous, large-scale method to fabricate phosphogypsum composites by reactive extrusion strategy. After curing for seven days, with more than 50 wt% of beta-hemihydrate phosphogypsum (β-HPG), the compressive strength and softening coefficient were 24.98 MPa and 0.78, increasing by 110.0% and 20.0%, respectively, compared to the pouring method. The results show that the screw extrusion process can improve the mechanical strength and waterproof properties of β-HPG hydration specimens without any special chemical admixtures and cements.
Dielectric Characteristics, Electrical Conductivity and Solvation of Ions in Electrolyte Solutions
Authors: Shcherbakov Vladimir V. , Artemkina Yuliya M. , Akimova Irina A. , Artemkina Irina M.
Published: September 2021

Solvation and association of ions in solutions largely depend on the dielectric properties of the solvent, the distance between ions in solutions, and temperature. This paper considers the effect of temperature on static dielectric constant (DC), dipole dielectric relaxation (DR) time, and limiting (ultimate) high frequency (HF) electrical conductivity (EC) of water and some polar solvents. In the investigated temperature range (0–370 °C), the static DC and DR time of water decrease, and limiting HF EC passes through a maximum at 250–300 °C with temperature growth. The dielectric characteristics of methanol, ethanol, and propanol behave in a similar way. It is shown that the existence of an HF EC temperature maximum is due to the different nature of the temperature dependences of DC and DR time. It is suggested that the same dependences are responsible for the presence of a maximum in the temperature dependences of the dissociation degree and the ionic product of water. The influence of non-electrolytes concentration as well as metal salts on the dielectric properties of their aqueous solutions is considered. The limiting HF EC of water determines the specific EC value of aqueous electrolyte solutions. Analysis of the absorption of microwave energy by polar solvents, as well as aqueous solutions of non-electrolytes and electrolytes, at a frequency of 2455 MHz is carried out. The optimal conditions for high-frequency heating of solutions have been established. The distance between ions in aqueous solutions of inorganic salts and in non-aqueous solutions of ionic liquids is calculated. It is shown that the maximum on the concentration dependence of the specific EC can be related to ions association.
Hard Tissue Volume Stability Effect beyond the Bony Envelope of a Three-Dimensional Preformed Titanium Mesh with Two Different Collagen Barrier Membranes on Peri-Implant Dehiscence Defects in the Anterior Maxilla: A Randomized Clinical Trial
Authors: Lee So-Ra , Jang Tae-Sik , Seo Chang-Su , Choi In-Oh , Lee Won-Pyo
Published: September 2021

This single-blinded, randomized, controlled study aimed to clinically and radiographically evaluate hard tissue volume stability beyond the bony envelope using three-dimensional preformed titanium mesh (3D-PFTM) for peri-implant dehiscence defects in the anterior maxilla. A total of 28 patients who wished to undergo implant surgery combined with guided bone regeneration (GBR) after extraction of a single maxillary anterior tooth were randomly assigned to two groups depending on the type of collagen membrane used, additionally with the 3D-PFTM—test (n = 14, cross-linked collagen membrane; CCM) and control (n = 14, non-cross-linked collagen membrane; NCCM) groups. Each implant was evaluated radiographically using CBCT at baseline, immediately after surgery, and at 6 months postoperatively. The relative position and distances from the bony envelope to the outlines of the augmented ridge were further determined immediately after GBR and 6 months after healing. At the platform level, the mean horizontal hard tissue gain (HG) at all the sites was 2.35 ± 0.68 mm at 6 months postoperatively. The mean HG rate was 84.25% ± 14.19% in the CCM group and 82.56% ± 13.04% in the NCCM group, but the difference was not significant between the groups. In all cases, HG was maintained beyond the bony envelope even after 6 months of GBR. This study suggests that 3D-PFTM should be considered a valuable option for GBR for peri-implant dehiscence defects in the anterior maxilla. In addition, 3D-PFTM may confer predictable hard tissue volume stability even after the healing period of hard tissue augmented outside the bony envelope by GBR.
Mechanical Properties and Deformation Mechanisms of Graphene Foams with Bi-Modal Sheet Thickness by Coarse-Grained Molecular Dynamics Simulations
Authors: Liu Shenggui , Lyu Mindong , Wang Chao
Published: September 2021

Graphene foams (GrFs) have been widely used as structural and/or functional materials in many practical applications. They are always assembled by thin and thick graphene sheets with multiple thicknesses; however, the effect of this basic structural feature has been poorly understood by existing theoretical models. Here, we propose a coarse-grained bi-modal GrF model composed of a mixture of 1-layer flexible and 8-layer stiff sheets to study the mechanical properties and deformation mechanisms based on the mesoscopic model of graphene sheets (Model. Simul. Mater. Sci. Eng. 2011, 19, 54003). It is found that the modulus increases almost linearly with an increased proportion of 8-layer sheets, which is well explained by the mixture rule; the strength decreases first and reaches the minimum value at a critical proportion of stiff sheets ~30%, which is well explained by the analysis of structural connectivity and deformation energy of bi-modal GrFs. Furthermore, high-stress regions are mainly dispersed in thick sheets, while large-strain areas mainly locate in thin ones. Both of them have a highly uneven distribution in GrFs due to the intrinsic heterogeneity in both structures and the mechanical properties of sheets. Moreover, the elastic recovery ability of GrFs can be enhanced by adding more thick sheets. These results should be helpful for us to understand and further guide the design of advanced GrF-based materials.
A Fuzzy Drive Strategy for an Intelligent Vehicle Controller Unit Integrated with Connected Data
Authors: Du Luyao , Ji Jun , Zhang Donghua , Zheng Hongjiang , Chen Wei
Published: September 2021

In order to improve vehicle control safety in intelligent and connected environments, a fuzzy drive control strategy is proposed. Through the fusion of vehicle driving data, an early warning level model was established, and the fuzzy control method was used to obtain the appropriate torque command under the vehicle condition; torque optimization processing was performed according to the different corresponding vehicle following characteristics. The control strategy was tested and verified on an established platform. Based on the experimental results, compared with the traditional drive strategy in one-way front and rear following scenarios, the vehicle avoided excessive opening and closing of the accelerator pedal when the distance between vehicles was close, maintained the correct distance in the following situation, and had better dynamic response when the distance between vehicles was large, indicating that the proposed drive strategy had a better real-time and security performance.
A Mathematical Model of Thyroid Disease Response to Radiotherapy
Authors: Gago-Arias Araceli , Neira Sara , Terragni Filippo , Pardo-Montero Juan
Published: September 2021

We present a mechanistic biomathematical model of molecular radiotherapy of thyroid disease. The general model consists of a set of differential equations describing the dynamics of different populations of thyroid cells with varying degrees of damage caused by radiotherapy (undamaged cells, sub-lethally damaged cells, doomed cells, and dead cells), as well as the dynamics of thyroglobulin and antithyroglobulin autoantibodies, which are important surrogates of treatment response. The model is presented in two flavours: on the one hand, as a deterministic continuous model, which is useful to fit populational data, and on the other hand, as a stochastic Markov model, which is particularly useful to investigate tumor control probabilities and treatment individualization. The model was used to fit the response dynamics (tumor/thyroid volumes, thyroglobulin and antithyroglobulin autoantibodies) observed in experimental studies of thyroid cancer and Graves’ disease treated with 131I-radiotherapy. A qualitative adequate fitting of the model to the experimental data was achieved. We also used the model to investigate treatment individualization strategies for differentiated thyroid cancer, aiming to improve the tumor control probability. We found that simple individualization strategies based on the absorbed dose in the tumor and tumor radiosensitivity (which are both magnitudes that can potentially be individually determined for every patient) can lead to an important raise of tumor control probabilities.
A Compendium of Infinite Group Theory: Part 1—Countable Recognizability
Authors: de Giovanni Francesco , Trombetti Marco
Published: September 2021

Countably recognizable group classes were introduced by Reinhold Baer and provide a very ingenious way to study large groups through the properties of their countable subgroups. This is the reason we have chosen the countable recognizability to start this series of survey papers on infinite group theory.
Enlargement of the Field of View Based on Image Region Prediction Using Thermal Videos
Authors: Batchuluun Ganbayar , Baek Na Rae , Park Kang Ryoung
Published: September 2021

Various studies have been conducted for detecting humans in images. However, there are the cases where a part of human body disappears in the input image and leaves the camera field of view (FOV). Moreover, there are the cases where a pedestrian comes into the FOV as a part of the body slowly appears. In these cases, human detection and tracking fail by existing methods. Therefore, we propose the method for predicting a wider region than the FOV of a thermal camera based on the image prediction generative adversarial network version 2 (IPGAN-2). When an experiment was conducted using the marathon subdataset of the Boston University-thermal infrared video benchmark open dataset, the proposed method showed higher image prediction (structural similarity index measure (SSIM) of 0.9437) and object detection (F1 score of 0.866, accuracy of 0.914, and intersection over union (IoU) of 0.730) accuracies than state-of-the-art methods.
Unsustainability Risk of Bid Bonds in Public Tenders
Authors: Giacomelli Jacopo , Passalacqua Luca
Published: September 2021

Public works contracts are commonly priced and awarded through a tender process. Each bidder joining the tender must underwrite a bid bond that guarantees their fitness as contractors in case of a win. The winning contractor also needs to underwrite a performance bond before entering the contract to protect the procuring entity against the performance risk arising during the execution phase. This study addresses the case when sureties refuse to issue the performance bond, despite having issued a bid bond to the same subject. A creditworthiness variation of the contractor during the tender or an excessive discount of the contract’s price may lead to this outcome. In that case, all the subjects involved are damaged. The surety who issued the bid bond has to indemnify the procuring entity. The contract award is nullified, which is financially harmful to both the contractor and the procuring entity. We show that sureties adopting a forward-looking risk appetite framework may prevent the demand for unsustainable performance bonds instead of addressing it by rejecting the bidders’ requests. The Solvency II regulatory framework, the Italian bidding law, and actual historical data available from the Italian construction sector are considered to specify a simplified model. The probability of unsustainable tender outcomes is numerically estimated by the model, together with the mitigating impact of a surety’s proper strategy.
New Improved Results for Oscillation of Fourth-Order Neutral Differential Equations
Authors: Moaaz Osama , El-Nabulsi Rami Ahmad , Muhib Ali , Elagan Sayed K. , Zakarya Mohammed
Published: September 2021

In this study, a new oscillation criterion for the fourth-order neutral delay differential equation ruxu+puxδu‴α′+quxβϕu=0,u≥u0 is established. By introducing a Riccati substitution, we obtain a new criterion for oscillation without requiring the existence of the unknown function. Furthermore, the new criterion improves and complements the previous results in the literature. The results obtained are illustrated by an example.
Robust Algorithms for Change-Point Regressions Using the t-Distribution
Authors: Lu Kang-Ping , Chang Shao-Tung
Published: September 2021

Regression models with change-points have been widely applied in various fields. Most methodologies for change-point regressions assume Gaussian errors. For many real data having longer-than-normal tails or atypical observations, the use of normal errors may unduly affect the fit of change-point regression models. This paper proposes two robust algorithms called EMT and FCT for change-point regressions by incorporating the t-distribution with the expectation and maximization algorithm and the fuzzy classification procedure, respectively. For better resistance to high leverage outliers, we introduce a modified version of the proposed method, which fits the t change-point regression model to the data after moderately pruning high leverage points. The selection of the degrees of freedom is discussed. The robustness properties of the proposed methods are also analyzed and validated. Simulation studies show the effectiveness and resistance of the proposed methods against outliers and heavy-tailed distributions. Extensive experiments demonstrate the preference of the t-based approach over normal-based methods for better robustness and computational efficiency. EMT and FCT generally work well, and FCT always performs better for less biased estimates, especially in cases of data contamination. Real examples show the need and the practicability of the proposed method.
On the Estrada Indices of Unicyclic Graphs with Fixed Diameters
Authors: Ning Wenjie , Wang Kun
Published: September 2021

The Estrada index of a graph G is defined as EE(G)=∑i=1neλi, where λ1,λ2,…,λn are the eigenvalues of the adjacency matrix of G. A unicyclic graph is a connected graph with a unique cycle. Let U(n,d) be the set of all unicyclic graphs with n vertices and diameter d. In this paper, we give some transformations which can be used to compare the Estrada indices of two graphs. Using these transformations, we determine the graphs with the maximum Estrada indices among U(n,d). We characterize two candidate graphs with the maximum Estrada index if d is odd and three candidate graphs with the maximum Estrada index if d is even.
Advanced Direct Vector Control Method for Optimizing the Operation of a Double-Powered Induction Generator-Based Dual-Rotor Wind Turbine System
Authors: Benbouhenni Habib , Bizon Nicu
Published: September 2021

The main goal of this paper is to increase the active/reactive power extracted from variable-speed dual-rotor wind power (DRWP) based on doubly-fed induction generators (DFIG) by optimizing its operation using advanced direct vector control. First, the dynamic modeling of different parts of the system is introduced. The DFIG is modeled in the Park reference system. After that, the control techniques are introduced in detail. Direct vector command (DVC) with four-level fuzzy pulse width modulation (FPWM) is used to control the rotor current, thereby controlling the reactive power and active power of the generator. Then, use the neural network design to replace the traditional proportional-integral (PI) controller. Finally, the Matlab/Simulink software is used for simulation to prove the effectiveness of the command strategy using 1.5 MW DRWP. The results show good performance in terms of response time, stability, and precision in following the reference under variable wind speed conditions. In addition, the total harmonic distortion (THD) value of stator current is about 0.13%, being a bit less than other THD values reported in the literature.