bluuebunny/crossref_metadata_2025 huggingface dataset:
Ceramic and Composite Polishing Systems for Milled Lithium Disilicate Restorative Materials: A 2D and 3D Comparative In Vitro Study
Authors: Jurado Carlos A. , Amarillas-Gastelum Clarisa , Afrashtehfar Kelvin I. , Argueta-Figueroa Liliana , Fischer Nicholas G. , Alshabib Abdulrahman
Published: August 2022

Purpose: This study aims to evaluate the effectiveness of two ceramic and two composite polishing systems for a novel chairside computer-aided design/computer-aided manufacturing (CAD/CAM) lithium disilicate ceramic with three-dimensional and two-dimensional microscopy images. This ceramic material can be used for implant-supported or tooth-borne single-unit prostheses. Materials and Methods: Sixty flat samples of novel chairside CAD/CAM reinforced lithium disilicate ceramic (Amber Mill, Hass Bio) were divided into five groups (n = 15/group) and treated as follows: Group 1 (NoP), no polished treatment; group 2 (CeDi), polished with ceramic Dialite LD (Brasseler USA); group 3, (CeOp) polished with ceramic OptraFine (Ivoclar Vivadent); group 4, (CoDi) polished with composite DiaComp (Brasseler USA), and group 5 (CoAs), polished with composite Astropol (Ivoclar Vivadent). The polished ceramic surface topography was observed and measured with three-dimensional and two-dimensional images. Results: All polishing systems significantly reduced the surface roughness compared with the non-polished control group (Sa 1.15 μm). Group 2 (CeDi) provided the smoothest surface arithmetical mean eight with 0.32 μm, followed by group 3 (CeOp) with 0.34 μm. Group 5 (CoAs) with 0.52 μm provided the smoothest surface among the composite polishing kits. Group 4 (CoDi) with 0.66 μm provided the least smooth surface among all polishing systems tested. Conclusions: Despite the effectiveness of ceramic polishing systems being superior to composite polishing systems of the CAD/CAM lithium disilicate restorative material, both polishing systems significantly improved the smoothness.
Is Wood a Material? Taking the Size Effect Seriously
Authors: Walley Stephen M. , Rogers Samuel J.
Published: August 2022

This review critically examines the various ways in which the mechanical properties of wood have been understood. Despite the immense global importance of wood in construction, most understanding of its elastic and inelastic properties is based on models developed for other materials. Such models neglect wood’s cellular and fibrous nature. This review thus questions how well models that were originally developed for homogeneous and effectively continuous materials can describe wood’s mechanical properties. For example, the elastic moduli of wood have been found by many authors to depend on the size of the test specimen. Such observations are incompatible with classical elasticity theory. There is also much uncertainty about how well elastic moduli can be defined for wood. An analysis of different models for size effects of various inelastic properties of wood shows that these models only approximate the observed behaviour, and do not predict or explain the scatter in the results. A more complete understanding of wood’s mechanical properties must take account of it being in some sense intermediate between a material and a structure.
A Novel Manufacturing Concept of LCP Fiber-Reinforced GPET-Based Sandwich Structures with an FDM 3D-Printed Core
Authors: Andrzejewski Jacek , Gronikowski Marcin , Aniśko Joanna
Published: August 2022

The presented research was focused on the development of a new method of sandwich structure manufacturing involving FDM-printing (fused deposition modeling) techniques and compression molding. The presented concept allows for the preparation of thermoplastic-based composites with enhanced mechanical properties. The sample preparation process consists of 3D printing the sandwich’s core structure using the FDM method. For comparison purposes, we used two types of GPET (copolymer of polyethylene terephthalate)-based filaments, pure resin, and carbon fiber (CF)-reinforced filaments. The outer reinforcing layer “skins” of the sandwich structure were prepared from the compression molded prepregs made from the LCP (liquid-crystal polymer)-fiber fabric with the GPET-based matrix. The final product consisting of an FDM-printed core and LCP-based prepreg was prepared using the compression molding method. The prepared samples were subjected to detailed materials analyses, including thermal analyses (thermogravimetry-TGA, differencial scanning calorimetry-DSC, and dynamic thermal-mechanical analysis-DMTA) and mechanical tests (tensile, flexural, and impact). As indicated by the static test results, the modulus and strength of the prepared composites were slightly improved; however, the stiffness of the prepared materials was more related to the presence of the CF-reinforced filament than the presence of the composite prepreg. The main advantage of using the developed method is revealed during impact tests. Due to the presence of long LCP fibers, the prepared sandwich samples are characterized by very high impact resistance. The impact strength increased from 1.7 kJ/m2 for pure GPET samples to 50.4 kJ/m2 for sandwich composites. For GPET/CF samples, the increase is even greater. The advantages of the developed solution were illustrated during puncture tests in which none of the sandwich samples were pierced.
Subgrain Coalescence Simulation by Means of an Advanced Statistical Model of Inelastic Deformation
Authors: Kondratev Nikita , Trusov Peter , Podsedertsev Andrej , Baldin Matvej
Published: August 2022

The development of technological methods for processing and manufacturing of functional (with a priori targeted properties) polycrystalline materials and products made of these materials still remains an acute problem. A multilevel modeling approach offers researchers the opportunity to describe inelastic deformation by applying internal variables that give an effective characterization of the material structure at different structural scale levels. High temperature plastic deformation is accompanied by these processes, which leads to a significant rearrangement of the meso- and microstructure of the material. The most substantial contribution to changing the properties of polycrystals is made by the evolution of grain and defect structures at the expense of dynamic recrystallization, which significantly depends on dynamic recovery. In this paper, we consider the problem of the coalescence of subgrains undergoing rotation during inelastic hot deformation. This process is called subgrain coalescence, and it is one of the dynamic recovery mechanisms responsible for changes in the fine subgrain structure. Under applied thermomechanical loads, the coalescence process promotes the formation of recrystallization nuclei and their subsequent growth, which can greatly change the grain structure of a polycrystal. The problem was solved in terms of the advanced statistical model of inelastic deformation, modified to describe the subgrain coalescence process. The model takes into account the local interactions between contacting structural elements (subgrains). These have to be considered so that the grain coalescence caused by a decrease in subboundary energies during their progressive merging can be adequately analyzed. For this purpose, a subgrain structure quite similar to the real structure was modeled using Laguerre polyhedra. Subgrain rotations were investigated using the developed model, which relies on the consideration of the excess density edge component of the same sign dislocations on incidental subgrain boundaries. The results of modeling of a copper polycrystal are presented, and the effects of temperature and strain rate on the subgrain coalescence process is demonstrated.
Performance of Building Solid Waste Powder in Cement Cementitious Material: A Review
Authors: Ji Yongcheng , Ji Wenhao , Li Wei
Published: August 2022

Recycled powder (RP) is a by-product of preparing recycled aggregates from construction waste through debris removal, step-by-step crushing, screening, and mechanical strengthening. It is a fine powder with a particle size of less than 75 μm. Reasonable use of RP can increase the utilization rate of construction waste and reduce dust pollution. This study introduces the current research status of RP. It describes the source of RP; the activation mode of activity; the effect on several aspects, such as early performance and mechanical properties of cement-based materials; and its mechanism of action in light of the research and development. Moreover, the linear regression analysis method was used to obtain the mathematical model between the content of RP and the performance of cement-based materials. The correlation degree between the content of RP and the performance of cement-based materials was obtained based on the gray relation analysis method. It was concluded that the change of the content of RP had the most significant influence on the compressive strength of foamed concrete over 28 d. Finally, some feasible suggestions and prospects for RP are provided.
Effect of Bimetallic-Activated Carbon Impregnation on Adsorption–Desorption Performance for Hydrogen Sulfide (H2S) Capture
Authors: Zulkefli Nurul Noramelya , Mathuray Veeran Loshinni S. , Noor Azam Adam Mohd Izhan , Masdar Mohd Shahbudin , Wan Isahak Wan Nor Roslam
Published: August 2022

This study reports on the impregnation of bi-metallic adsorbents based on commercial coconut activated carbon (CAC), surface-modified with metal acetate (ZnAc2), metal oxide (ZnO and TiO2), and the basic compound potassium hydroxide (KOH). The morphology of the adsorbents was then characterized with SEM-EDX, the microporosity was determined using Brunauer–Emmett–Teller (BET) analysis, the thermal stability was investigated via thermogravity analysis (TGA), and functional group analysis was undertaken with Fourier-transform infrared (FTIR) spectroscopy. These modified adsorbents were subjected to a real adsorption test for H2S capture using a 1 L adsorber with 5000 ppm H2S balanced for N2, with temperature and pressure maintained at an ambient condition. Adsorption–desorption was carried out in three cycles with the blower temperature varied from 50 °C to 150 °C as the desorption condition. Characterization results revealed that the impregnated solution homogeneously covered the adsorbent surface, effecting the morphology and properties. Based on this study, it was found that ZnAc2/TiO2/CAC_DCM showed a significant increase in adsorption capacity with the different temperatures applied for the desorption in the second cycle: 1.67 mg H2S/g at 50 °C, 1.84 mg H2S/g at 100 °C, and 1.96 mg H2S/g at 150 °C. ZnAc2/ZnO/CAC_DCM seemed to produce the lowest percentage of degradation in the three cycles for all the temperatures used in the adsorption–desorption process. Therefore, ZnAc2/ZnO/CAC_DCM has the potential to be used and commercialized for biogas purification for H2S removal.
Alkali Niobate Powder Synthesis Using an Emerging Microwave-Assisted Hydrothermal Method
Authors: Dumitrescu Cristina-Rodica , Surdu Vasile-Adrian , Stroescu Hermine , Nicoara Adrian-Ionut , Neacsu Ionela Andreea , Trusca Roxana , Andronescu Ecaterina , Ciocan Lucian Toma
Published: August 2022

For more than five decades, alkali niobate-based materials (KxNa1−xNbO3) have been one of the most promising lead-free piezoelectric materials researched to be used in electronics, photocatalysis, energy storage/conversion and medical applications, due to their important health and environmentally friendly nature. In this paper, our strategy was to synthetize the nearest reproductible composition to KxNa1−xNbO3 (KNN) with x = 0.5, placed at the limit of the morphotropic phase boundary (MPB) with the presence of both polymorphic phases, orthorhombic and tetragonal. The wet synthesis route was chosen to make the mix crystal powders, starting with the suspension preparation of Nb2O5 powder and KOH and NaOH alkaline solutions. Hydrothermal microwave-assisted maturation (HTMW), following the parameter variation T = 200–250 °C, p = 47–60 bar and dwelling time of 30–90 min, was performed. All powders therefore synthesized were entirely KxN1−xNbO3 solid solutions with x = 0.06–0.69, and the compositional, elemental, structural and morphological characterization highlighted polycrystalline particle assemblage with cubic and prismatic morphology, with sizes between 0.28 nm and 2.95 μm and polymorphic O-T phase coexistence, and a d33 piezoelectric constant under 1 pC/N of the compacted unsintered and unpoled discs were found.
Ultra-Broadband Mid-Infrared Metamaterial Absorber Based on Multi-Sized Resonators
Authors: Huang Xiaojun , Zhou Ziliang , Cao Miao , Li Rong , Sun Cuizhen , Li Xiaoyan
Published: August 2022

Mid-infrared metamaterial absorbers have many applications in the field of infrared detection, infrared thermal energy utilization, radiation refrigeration, invisible camouflage, etc. In this study, we designed an ultra-broadband mid-infrared metamaterial absorber based on multi-sized resonators. The structure of the absorber consisted of a gold substrate and nine resonators. The simulated results showed that the absorptivity of the absorber was higher than 90% in the 8.33–15.09 μm waveband with an average absorptivity of 95.17%. The energy distributions of the electric and magnetic fields were introduced to investigate the physics of broadband absorption. Moreover, we combined the multi-layer structure with the plane random arrangement structure to achieve a balance between thickness and width. Our study further illustrates the potential application of multi-sized resonators in metamaterial absorbers to realize high absorptivity and ultra-broadband to improve the performance of devices applied in infrared detection, radiation refrigeration, and other fields.
Characteristics and Sonophotocatalytic Activity of Natural Sphalerite under Ultrasonic (1.7 MHz) and UVA LED (365 nm) Irradiation
Authors: Popova Svetlana , Tazetdinova Victoria , Pavlova Erzhena , Matafonova Galina , Batoev Valeriy
Published: August 2022

Naturally occurring sono- and photoactive minerals, which are abundant on Earth, represent an attractive alternative to the synthesized sonophotocatalysts as cost-effective materials for water and wastewater treatment. This study focuses on characterizing and evaluating the sonophotocatalytic activity of natural sphalerite (NatS) from Dovatka deposit (Siberia) under high-frequency ultrasonic (US, 1.7 MHz) and ultraviolet light-emitting diodes (UVA LED, 365 nm) irradiation towards degradation of 4-chlorophenol as a model organic pollutant. Since raw natural sphalerite did not exhibit a measurable photocatalytic activity, it was calcined at 500, 900 and 1200 °C. The natural sphalerite after calcination at 900 °C (NatS*) was found to be the most effective for sonophotocatalytic degradation of 4-chlorophenol, attaining the highest efficiency (55%, 1 h exposure) in the following row: UV < US ≈ UV/US ≈ US/NatS* < UV/NatS* < UV/US/NatS*. Addition of 1 mM H2O2 increased the removal to 74% by UV/US/NatS*/H2O2 process. An additive effect between UV/NatS* and US/NatS* processes was observed in the sonophotocatalytic system as well as in the H2O2-assisted system. We assume that the sonophotocatalytic hybrid process, which is based on the simultaneous use of high-frequency ultrasound, UVA light, calcined natural sphalerite and H2O2, could provide a basis of an environmentally safe and cost-effective method of elimination of organic pollutants from aqueous media.
Spectroscopic Characterization and Antioxidant Properties of Mandelic Acid and Its Derivatives in a Theoretical and Experimental Approach
Authors: Parcheta Monika , Świsłocka Renata , Świderski Grzegorz , Matejczyk Marzena , Lewandowski Włodzimierz
Published: August 2022

The following article discusses the antioxidant properties of mandelic acid and its hydroxy and methoxy derivatives. The antioxidant capacity of these compounds is determined by DPPH, FRAP, CUPRAC and ABTS. The mechanisms underlying the antioxidant properties are described by BDE, IP, PDE, ETE and PA calculation method values and referenced to experimental data. Thermochemistry, HOMO/LUMO energies, dipole moments, charge distribution, IR, RAMAN, NMR frequencies, binding lengths and angles were calculated using the B3LYP method and the 6-311++G(d,p) basis set. The structure of mandelic acid and its derivatives was determined experimentally using IR and RAMAN spectroscopy.
Analysis of The Working Performance of Large Curvature Prestressed Concrete Box Girder Bridges
Authors: Yuan Jian , Luo Liang , Zheng Yuzhou , Yu Suhui , Shi Jun , Wang Jianan , Shen Jiyang
Published: August 2022

Based on numerical shape functions and the structural stressing state theory, the mechanical properties of the curved prestressed concrete box girder (CPCBG) bridge model under different loading cases are presented. First, the generalized strain energy density (GSED) obtained from the measured strain data is used to represent the stressing state pattern of the structure; then, the stressing state of the concrete section is analyzed by plotting the strain and stress fields of the bridge model. The stressing state pattern and strain fields of the CPCBG are shown to reveal its mechanical properties. In addition, the measured concrete strain data are interpolated by the non-sample point interpolation (NPI) method. The strain and stress fields of the bridge model have been plotted to analyze the stressing state of the concrete cross-section. The internal forces in the concrete sections are calculated by using interpolated strains. Finally, the torsional effects are simulated by measuring the displacements to show the torsional behavior of the cross-section. The analysis and comparison of the internal force and strain fields reveal the common and different mechanical properties of the bridge model. The results of the analysis of the curved bridge model provide a reference for the future rational design of bridge projects.
Elaboration and Characterization of WMoTaNb High Entropy Alloy Prepared by Powder Metallurgy Processes
Authors: Moser Mathias , Dine Sarah , Vrel Dominique , Perrière Loïc , Pirès-Brazuna Rémy , Couque Hervé , Bernard Frédéric
Published: August 2022

This work concerns the sintering of tungsten-based (i.e WMoTaNb) high entropy alloy (HEA) powders using the spark plasma sintering (SPS) technique and their mechanical properties. The synthesis was performed by a self-propagating high-temperature synthesis (SHS) type reaction in which the mixture of metallic oxides (WO3, MoO3 …) is reduced by magnesium. For this, a specific reactor has been developed. Different conditions including the addition of a moderator were tested. These powders are then densified by SPS technology which allows for keeping the initial microstructure of the powder. The optimization of sintering conditions was performed with the objective to control simultaneously the chemical composition, the grain growth and the densification stages.
Modeling of Heat Transfer through Firefighters Multilayer Protective Clothing Using the Computational Fluid Dynamics Assisted by X-ray Microtomography and Thermography
Authors: Renard Morgan , Puszkarz Adam K.
Published: August 2022

This paper explores the modeling of physical phenomena that occur in clothing that affect the safety and biophysical comfort of the user. Three-dimensional models of textile assemblies with complex morphology used in firefighters’ multilayer protective clothing were designed in a CAD environment. The main goal of the research was to design and experimentally verify (by thermography) the models in terms of simulations when the heat transfer occurs through them in selected ambient conditions using the finite volume method. The designed models took into account the subtle differences in the geometry of selected assemblies determined by high-resolution X-ray microtomography. The designed models made it possible to calculate heat transport with a difference of about 2% to 5% in comparison to experiment that depend on the ambient conditions and the complexity of the model geometry. Moreover, the comparison of the simulation results with the experimental outcomes shows that the mapping of subtle differences in the internal structure of the assemblies in the designed models allows us to observe differences in the modeled heat transfer.
LTA and FAU-X Iron-Enriched Zeolites: Use for Phosphate Removal from Aqueous Medium
Authors: Guaya Diana , Cobos Hernán , Camacho Jhulissa , López Carmen Milena , Valderrama César , Cortina José Luis
Published: August 2022

Hydrothermally synthesized Linde type A (LTA) and faujasite X (FAU-X) zeolites are low-cost and environmentally benign inorganic carriers for environmental applications. In this study, (oxy)hydroxides were incorporated onto LTA and FAU-X zeolites to promote the phosphate adsorption. The performance of LTA-Fe and FAU-X-Fe was evaluated through batch adsorption assays. A complete evaluation was performed to recover phosphate from synthetic wastewater. The effect of pH, concentration, equilibrium, and kinetic parameters on phosphate adsorption and its further reuse in sorption–desorption cycles were evaluated. LTA-Fe and FAU-X-Fe are effective for adsorption of phosphate at neutral (e.g., pH 7.0 ± 0.2) and in a broad range of phosphate concentrations. Higher ratios of adsorption capacities were obtained by synthetic zeolites enriched with iron in comparison to their parent forms. The phosphate adsorption occurred through hydrogen bonding and complexation reactions between protonated iron hydroxyl groups and phosphate anions. The phosphate monolayer adsorption was followed by diffusion through the internal pores and 80% of the equilibrium adsorption was reached within 50 min. The LTA-Fe and FAU-X-Fe can be used for phosphate recovery from wastewater treatment plants. The use of LTA-Fe and FAU-X-Fe in a tertiary wastewater treatment stage could allow to reduce the phosphate–phosphorous content, reaching the regulatory levels (equal 1 mg L−1 total phosphorous). The phosphate adsorption using LTA-Fe and FAU-X-Fe does not require pH adjustment, and it is endothermic. The reusability of both iron zeolites is limited, and they can be finally disposed for soil amendment applications.
High Critical Current Density in the Textured Nanofiber Structure in Multifilament MgB2 Wires Made by the Powder-In-Tube (PIT) Technique
Authors: Gajda Daniel , Zaleski Andrzej J. , Morawski Andrzej J. , Małecka Małgorzata , Tran Lan Maria , Rindfleisch Matt , Durejko Tomasz , Czujko Tomasz
Published: August 2022

We show that the structure of multifilament MgB2 wires made by the powder-in-tube (PIT) method can be texturized by annealing the structure under high isostatic pressure. Our results show that we obtained continuous fibers with a uniform diameter of 250 nm in all 36 filaments, a small grain size of approximately 50 nm and a high density of the superconducting material. These results contribute to a significant improvement in the critical current density in high magnetic fields, e.g., 100 A/mm2 at 14 T and 4.2 K.
Ultrafast Studies of ZrTe3 by Transient Absorption Spectrometer
Authors: Ahmed Shakeel , Rui Wang , Altaf Faizah , Khan Jahanzeb , Bocchetta Patrizia , Zhang Han
Published: August 2022

Two-dimensional (2D) tri-TMDCs carrier dynamics provide a platform for studying excitons through Ultrafast Pump-Probe Transient Absorption Spectroscopy. Here we studied the ZrTe3 nanosheets (NTs) exciton dynamics by transient absorption (TA) spectrometer. We observed different carrier dynamics in the ZrTe3 NTs sample at different pump powers and with many wavelengths in the transient absorption spectrometer. The shorter life decay constant is associated with electron-phonon relaxation. Similarly, the longer-life decay constant represents the long live process that is associated with charge separation. The interactions between carrier-phonons at nanoscale materials can be changed by phonons quantum confinements. The hot carrier lifetime determined the strength of carrier phonon interactions. The value of fast decay in the conduction band is due to carrier relaxation or the carrier gets trapped due to surface states or localized defects. The value of slow decay is due to the recombination of surface state and localized defects processes. The lifetime declines for long wavelengths as size decreases. Whereas, during short wavelength-independent decay, carrier characteristics have been observed. TA spectroscopy is employed to investigate insight information of the carrier’s dynamical processes such as carrier lifetime, cooling dynamics, carrier diffusion, and carrier excitations. The absorption enhanced along excitons density with the increase of pump power, which caused a greater number of carriers in the excited state than in the ground state. The TA signals consist of trap carriers and (electron-hole) constituents, which can be increased by TA changes that rely on photoexcitation and carrier properties.
New Ceramic Multi-Unit Dental Abutments with an Antimicrobial Glassy Coating
Authors: López-Píriz Roberto , Goyos-Ball Lidia , Cabal Belén , Martínez Susana , Moya José S. , Bartolomé José F. , Torrecillas Ramón
Published: August 2022

The choice of suitable materials and new designs in oral implantology and the subsequent enhancement of the characteristics of the dental implant developed is an important research topic with wide scope. The present work aims to develop a new multifunctional zirconia–ceria/alumina (Ce–TZP/Al2O3) composite with an antimicrobial glass-based coating to be used in multi-unit abutments compatible with commercially available Ti implants for peri-implantitis prevention. An airbrush spraying technique was effectively applied to coat the sintered ceramic composite starting from a glass powder suspension. This deposition technique was appropriate for obtaining continuous antimicrobial glass-based coatings with homogenous thickness (~35 µm) on ceramic dental implant components. The dental implant systems with the antimicrobial glassy coating were subjected to a mechanical integrity test following ISO 14801 to determine their long-term stability. The tested implant-coating structure seems to be stable under in vitro conditions with ultimate applied forces exceeding the maximum physiological occlusal loading force. This paper also presents a pilot clinical case report that shows peri-implant tissue around the mechanically stable glass coating with no signs of inflammation 1 year after implant insertion. This result is a preliminary probe of the durability and biological tolerance of the glassy material by the gingiva, as well as the antimicrobial effect on the peri-implant microbiota displayed by the coating.
Impact of the Heat Treatment Duration on Color and Selected Mechanical and Chemical Properties of Scots Pine Wood
Authors: Piernik Magdalena , Woźniak Magdalena , Pinkowski Grzegorz , Szentner Kinga , Ratajczak Izabela , Krauss Andrzej
Published: August 2022

The aim of this study was to assess the effect of the duration of heat treatment on changes in the color, as well as the chemical and mechanical properties of Scots pine sapwood. An important element of the research was to obtain the assumed temperature in the entire volume of samples. Quantitative changes in color and its components were recorded, while mechanical properties were determined in tests of compressive strength parallel and perpendicular to the grain, longitudinal tensile strength and modulus of elasticity and impact strength. The novelty of the research was to determine the above-mentioned parameters for twin samples with identical moisture contents. Chemical analyses were conducted on heat-treated wood that was subjected to heat treatment at 220 °C for a period from 1 to 8 h. Extension of the heat treatment duration resulted in the increasing darkening of the wood, as well as a further reduction in the impact strength and tensile strength parallel to the grain by approx. 40 and 50%, respectively, compared to the control wood, but also compared to heat-treated wood for a shorter treatment duration. The heat treatment of wood caused changes in the contents of the wood components, as well as the elemental composition in the heat-treated wood, compared to the control pine. The changes in the structure of the heat-treated wood were confirmed by the attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Observed quantitative changes in the main wood components, its structural changes, as well as wood decomposition and increased crystallinity of cellulose explain significant changes in both the mechanical properties and the color of heat-treated wood.
Multi-Criteria Optimisation of Friction Stir Welding Parameters for EN AW-2024-T3 Aluminium Alloy Joints
Authors: Kubit Andrzej , Trzepieciński Tomasz , Kluz Rafał , Ochałek Krzysztof , Slota Ján
Published: August 2022

The aim of this research was the selection of friction stir welding (FSW) parameters for joining stiffening elements (Z-stringers) to a thin-walled structure (skin) made of 1 mm-thick EN AW-2024 T3 aluminium alloy sheets. Overlapping sheets were friction stir welded with variable values of welding speed, pin length (plunge depth), and tool rotational speed. The experimental research was carried out based on a three-factor three-level full factorial Design of Experiments plan (DoE). The load capacity of the welded joints was determined in uniaxial tensile/pure shear tests. Based on the results of the load capacity of the joint and the dispersion of this parameter, multi-criteria optimisation was carried out to indicate the appropriate parameters of the linear FSW process. The optimal parameters of the FSW process were determined based on a regression equation assessed by the Fisher–Senecor test. The vast majority of articles reviewed concern the optimisation of welding parameters for only one selected output parameter (most often joint strength). The aim of multi-criteria optimisation was to determine the most favourable combination of parameters in terms of both the smallest dispersion and highest load capacity of the joints. It was found that an increase in welding speed at a given value of pin length caused a decrease in the load capacity of the joint, as well as a significant increase in the dispersion of the results. The use of the parameters obtained as a result of multi-criteria optimisation will allow a minimum load capacity of the joints of 5.38 kN to be obtained with much greater stability of the results.
Uniaxial Compressive Stress–Strain Relation of Recycled Coarse Aggregate Concrete with Different Carbonation Depths
Authors: Tu Kun , Wu Jin , Wang Yiyuan , Deng Huachao , Zhang Rui
Published: August 2022

The stress–strain relation of recycled aggregate concrete (RAC) after carbonation is very important to the assessment of the durability of RAC. The objective of this study is to investigate the uniaxial compressive stress–strain curves of RAC after carbonation. In this study, the specimens were prepared with 70-mm diameter and 140-mm height cylinders, and the carbonation of the specimens was accelerated after curing 28 days. Then a uniaxial compressive loading test on the specimens was performed by using a mechanical testing machine. The results show that the peak stress (σ0) and elastic modulus (Ec) of all specimens increase with the increase of carbonation depth. The ratio of ultimate strain to peak strain (εu/ε0) and relative toughness of the specimens decrease with the increase of carbonation depth. Furthermore, carbonation has a stronger effect on natural coarse aggregate concrete (NAC) than the 50% replacement rate of RAC with similar compressive strength. Stress–strain models of recycled aggregate concrete with different carbonation depths were established according to experimental results.
A Novel Auxiliary Excretion Approach to a Lavatory Robot with Safety and Robustness
Authors: Zhao Donghui , Zhang Zihan , Yang Junyou , Wang Shuoyu , Hiroshi Yokoi
Published: August 2022

The excretion behavior in daily life for the elderly and the disabled is a high frequency, high physical load, and risky behavior. Therefore, we proposed an auxiliary lavatory robot (ALR) with autonomous movement and self-cleaning capability. When the nursing staff assists a user in transferring from a standing or lying state to sitting on the ALR, the ALR can follow the user according to their position and posture. Over the whole transfer process, the ALR always provides the user with the best transfer position and posture, which is an effective approach to reduce workload and physical load. However, confusion and occlusion of the lower limbs between the nursing staff and the user would affect the user’s posture recognition. First, in this paper, a method combined with object segmentation and shape constraint was proposed to extract the contour of the lower limbs of the user and the nursing staff. Then, depending on the position constraint and dynamic characteristics of the legs contour and back contour of the user, a dynamic posture recognition approach based on a two-level joint probabilistic data association algorithm (JPDA) was proposed. Finally, the leg target recognition experiment, path-tracking experiment, and auxiliary excretion transfer experiment were implemented to verify the effectiveness and robustness of our proposed algorithm. The experimental results showed that our proposed method improved the safety and convenience of the user, and it also reduced the workload and physical load of the nursing staff. The ALR, integrated with the proposed method, has a good universal property for the elderly and disabled with weak motion capability in hospitals, pension centers, and families.
Mathematical Modeling and Machining of the Internal Double-Arc Spiral Bevel Gear by Finger Milling Cutters for the Nutation Drive Mechanism
Authors: Zhang Dawei , Wang Zhenya , Yao Ligang , Xie Daizhi
Published: August 2022

A method of machining the internal double-arc spiral bevel gear with a finger milling cutter was presented. The mathematical model of the internal spiral bevel gear tooth profile was established considering the principle of machining a spiral bevel gear by the generating method, and a three-dimensional (3D) tooth profile graph was developed. Subsequently, by applying the gear meshing theory, the 3D model of the tooth alignment curve for the finger milling cutter was established. Based on the tooth surface equation of crown gear, the cutter intercept equation was derived. The cutter was divided into four finger milling cutters considering the design difficulty of the cutter, which is used to manufacture different arc segments of the double-arc tooth profile, respectively. The special machining tool model of the internal spiral bevel gear was further developed by using SolidCam, and the simulation experiment was carried out. The simulated gear model was compared with the theoretical gear model and the error of the simulation experiment was estimated. Actual machining on the machine tool and the internal spiral bevel gear were inspected. The maximum error is 0.035 mm, and the minimum error is 0.005 mm. The machining accuracy meets the requirements. The feasibility of machining the internal double-arc spiral bevel gear with a finger milling cutter was verified.
Synthesis and Single Crystal Growth by Floating Zone Technique of FeCr2O4 Multiferroic Spinel: Its Structure, Composition, and Magnetic Properties
Authors: Batulin Ruslan , Cherosov Mikhail , Kiiamov Airat , Zinnatullin Almaz , Vagizov Farit , Tayurskii Dmitrii , Yusupov Roman
Published: August 2022

We present the new synthesis root of spinel-structure FeCr2O4 and its single crystal growth by the optical floating zone method, ensuring its single phase and near-ideal composition. The advantage of the proposed synthesis method is the creation of the reducing atmosphere in the oven needed for preserving the Fe2+ oxidation state via decomposition of the iron (II) oxalate FeC2O4 used as one of the initial components. The occurrence of the Fe3+ ions in the obtained polycrystalline samples as well as grown single crystals was carefully monitored by means of Mössbauer spectroscopy. Magnetic susceptibility and heat capacity temperature dependences reveal a sequence of the structural (138 K) and magnetic (at 65 K and 38 K) phase transition characteristics for the FeCr2O4 compound.
Antifouling Marine Coatings with a Potentially Safer and Sustainable Synthetic Polyphenolic Derivative
Authors: Neves Ana R. , Gomes Luciana C. , Faria Sara I. , Sousa João , Ruivo Raquel , Páscoa Inês , Pinto Madalena , Sousa Emília , Santos Miguel M. , Silva Elisabete R. , Correia-da-Silva Marta , Mergulhão Filipe
Published: August 2022

The development of harmless substances to replace biocide-based coatings used to prevent or manage marine biofouling and its unwanted consequences is urgent. The formation of biofilms on submerged marine surfaces is one of the first steps in the marine biofouling process, which facilitates the further settlement of macrofoulers. Anti-biofilm properties of a synthetic polyphenolic compound, with previously described anti-settlement activity against macrofoulers, were explored in this work. In solution this new compound was able to prevent biofilm formation and reduce a pre-formed biofilm produced by the marine bacterium, Pseudoalteromonas tunicata. Then, this compound was applied to a marine coating and the formation of P. tunicata biofilms was assessed under hydrodynamic conditions to mimic the marine environment. For this purpose, polyurethane (PU)-based coating formulations containing 1 and 2 wt.% of the compound were prepared based on a prior developed methodology. The most effective formulation in reducing the biofilm cell number, biovolume, and thickness was the PU-based coating containing an aziridine-based crosslinker and 2 wt.% of the compound. To assess the marine ecotoxicity impact of this compound, its potential to disrupt endocrine processes was evaluated through the modulation of two nuclear receptors (NRs), peroxisome proliferator-activated receptor γ (PPARγ), and pregnane X receptor (PXR). Transcriptional activation of the selected NRs upon exposure to the polyphenolic compound (10 µM) was not observed, thus highlighting the eco-friendliness towards the addressed NRs of this new dual-acting anti-macro- and anti-microfouling agent towards the addressed NRs.
Kinetics of Lignin Removal from the Lignocellulosic Matrix after Ozone Transportation
Authors: Baig Khurram Shahzad
Published: August 2022

This study presents a new method to remove lignin from wheat straw (lignocellulosic) using the ozonation technique. Lignocellulosic material is a complex biopolymer composed of cellulose, hemicellulose and lignin. Apart from lignin, which acts as a chemical resistant, lignocellulosic is the main resource of cellulose and hemicellulose sugars. The ozonation reaction takes place in a two-phase solid–gas fluidization stainless steel reactor. The focus of this paper is to investigate the kinetics that govern lignin removal from lignocellulosic material after ozonation treatment. The kinetics of lignin removal did not agree with the experimental data until the suggested model is modified to a pseudo-second-order. The results showed that at a higher ozone supply of 150 mg min−1, the surface reaction and intra-particular diffusion were the most significant factors to remove the lignin. Moreover, at a lower ozone supply of 30 mg min−1, the intra-particular diffusion was the only contributor towards lignin removal.
Carcass Characteristics and Meat Quality of Ross 308 Broiler Chickens Fed Malted Red and White Sorghum-Based Diets
Authors: Moses Chandapiwa , Manyeula Freddy , Radikara Malebogo Virginia , Mareko Molebeledi Horatious Dambe , Madibela Othusitse Ricky
Published: August 2022

In this study, the effects of malted sorghum-based diets (MSBD) on carcass characteristics and meat quality were investigated in broiler chickens. Two-week-old Ross 308 broilers were randomly allocated to three groups (each with five replications) and were then reared on either 0 or 100% (red (Mr Buster) or white (Segaolane)) malted sorghum commercial diets. The highest (p < 0.05) slaughter weights, hot carcass weights, and cold carcass weights were observed for the broilers reared on the control diets. Broilers reared on MSBD had high (p < 0.05) drumstick–thigh and vertebrae weights. The broilers fed the malted red sorghum-based diet (MRSBD) had the longest (p < 0.05) small intestine and highest gizzard and liver percentage. The pHi of the broilers fed MRSBD was higher (p < 0.05) than the broilers on the control or malted white sorghum-based diet (MWSBD). Breast muscle crude fibre was the lowest (p ˂ 0.05) for the MRSBD and phosphorus was low (p ˂ 0.005) for MSBD broilers. The highest (p < 0.05) muscle potassium and magnesium was found in the control diet broilers. The carcass characteristics, internal organs, and meat quality traits of the broilers fed MSBD compared well to those fed the control diets. It is concluded that malted sorghum grains are a potential alternative energy source to maize for broiler diets and could reduce competition for maize grains between livestock and human use.
AsymmeTree: A Flexible Python Package for the Simulation of Complex Gene Family Histories
Authors: Schaller David , Hellmuth Marc , Stadler Peter F.
Published: August 2022

AsymmeTree is a flexible and easy-to-use Python package for the simulation of gene family histories. It simulates species trees and considers the joint action of gene duplication, loss, conversion, and horizontal transfer to evolve gene families along the species tree. To generate realistic scenarios, evolution rate heterogeneity from various sources is modeled. Finally, nucleotide or amino acid sequences (optionally with indels, among-site rate heterogeneity, and invariant sites) can be simulated along the gene phylogenies. For all steps, users can choose from a spectrum of alternative methods and parameters. These choices include most options that are commonly used in comparable tools but also some that are usually not found, such as the innovation model for species evolution. While output files for each individual step can be generated, AsymmeTree is primarily intended to be integrated in complex Python pipelines designed to assess the performance of data analysis methods. It allows the user to interact with, analyze, and possibly manipulate the simulated scenarios. AsymmeTree is freely available on GitHub.
A Novel Biopsy Capsule Robot Based on High-Speed Cutting Tissue
Authors: Song Zhibin , Zhang Wenjie , Zhang Wenhui , Paolo Dario
Published: August 2022

The capsule robot (CR) is a promising endoscopic method in gastrointestinal diagnosis because of its low discomfort to users. Most CRs are used to acquire image information only and lack the ability to collect samples. Although some biopsy capsule robots (BCRs) have been developed, it remains challenging to acquire the intestinal tissue while avoiding tearing and adhesion due to the flexibility of colonic tissue. In this study, we develop a BCR with a novel sampling strategy in which soft tissue is scratched with sharp blades rotating at high speed to avoid tissue tearing. In the BCR design, a spiral spring with prestored energy is used to release high energy within a short period of time, which is difficult for a motor or magnet to perform within a small capacity installation space. The energy of the tightened spiral spring is transmitted to drive sharp blades to rotate quickly via a designed gear mechanism. To guarantee reliable sampling, a Bowden cable is used to transmit the user’s manipulation to trigger the rotation of the blades, and the triggering force transmitted by the cable can be monitored in real time by a force sensor installed at the manipulating end. A prototype of the proposed BCR is designed and fabricated, and its performance is tested through in vitro experiments. The results show that the proposed BCR is effective and the size of its acquired samples satisfies clinical requirements.
Lateral Hypothalamus Calcium/Calmodulin-Dependent Protein Kinase II
α
Neurons Encode Novelty-Seeking Signals to Promote Predatory Eating
Authors: Tan Na , Shi Jiaying , Xu Lingyu , Zheng Yanrong , Wang Xia , Lai Nanxi , Fang Zhuowen , Chen Jialu , Wang Yi , Chen Zhong
Published: August 2022

Predatory hunting is an innate appetite-driven and evolutionarily conserved behavior essential for animal survival, integrating sequential behaviors including searching, pursuit, attack, retrieval, and ultimately consumption. Nevertheless, neural circuits underlying hunting behavior with different features remain largely unexplored. Here, we deciphered a novel function of lateral hypothalamus (LH) calcium/calmodulin-dependent protein kinase II
α
(CaMKII
α
+
) neurons in hunting behavior and uncovered upstream/downstream circuit basis. LH CaMKII
α
+
neurons bidirectionally modulate novelty-seeking behavior, predatory attack, and eating in hunting behavior. LH CaMKII
α
+
neurons integrate hunting-related novelty-seeking information from the medial preoptic area (MPOA) and project to the ventral periaqueductal gray (vPAG) to promote predatory eating. Our results demonstrate that LH CaMKII
α
+
neurons are the key hub that integrate MPOA-conveyed novelty-seeking signals and encode predatory eating in hunting behavior, which enriched the neuronal substrate of hunting behavior.
Mobile Sensing in the COVID-19 Era: A Review
Authors: Wang Zhiyuan , Xiong Haoyi , Tang Mingyue , Boukhechba Mehdi , Flickinger Tabor E. , Barnes Laura E.
Published: August 2022

Background
. During the COVID-19 pandemic, mobile sensing and data analytics techniques have demonstrated their capabilities in monitoring the trajectories of the pandemic, by collecting behavioral, physiological, and mobility data on individual, neighborhood, city, and national scales. Notably, mobile sensing has become a promising way to detect individuals’ infectious status, track the change in long-term health, trace the epidemics in communities, and monitor the evolution of viruses and subspecies.
Methods
. We followed the PRISMA practice and reviewed 60 eligible papers on mobile sensing for monitoring COVID-19. We proposed a taxonomy system to summarize literature by the
time duration
and
population scale
under mobile sensing studies.
Results
. We found that existing literature can be naturally grouped in
four clusters
, including
remote detection
,
long-term tracking
,
contact tracing
, and
epidemiological study
. We summarized each group and analyzed representative works with regard to the system design, health outcomes, and limitations on techniques and societal factors. We further discussed the implications and future directions of mobile sensing in communicable diseases from the perspectives of technology and applications.
Conclusion
. Mobile sensing techniques are effective, efficient, and flexible to surveil COVID-19 in scales of time and populations. In the post-COVID era, technical and societal issues in mobile sensing are expected to be addressed to improve healthcare and social outcomes.