bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Adhesion Property and Moisture Effect between SBS Modified Asphalt Binder and Aggregate Using Molecular Dynamics Simulation
Authors: Guo Fucheng , Pei Jianzhong , Zhang Jiupeng , Li Rui , Liu Pengfei , Wang Di
Published: October 2022

In this project, the adhesion property and moisture effect between styrene–butadiene–styrene (SBS) modified asphalt binder and aggregate were studied to reveal their interface adhesion mechanism. The influence of SBS contents on adhesion property and moisture effect between binder and aggregate phases were investigated using molecular dynamics simulation. Moreover, the double-layer adhesion models of asphalt binder–aggregate and triple-layer debonding models of asphalt binder–water–aggregate were constructed and equilibrated, and the adhesion property and the moisture effect were evaluated numerically. The results indicate that the built SBS-modified asphalt binder models show favorable reliability in representing the real one. The variation in the work of adhesion for SBS modified asphalt binder–quartz is not remarkable with the SBS content when its content is relatively low. However, the work of adhesion decreased significantly when the content was higher than 6 wt.%, which is consistent with the experimental results. The adhesion between SBS-modified asphalt binder and quartz is derived from Van der Waals energy. The modified asphalt binder with a high SBS modifier content (8 wt.% and 10 wt.%) shows much better moisture resistance (nearly 30% improved) than the unmodified asphalt binder from the work of debonding results. According to the Energy Ratio (ER) values, asphalt binders with high SBS content (8 wt.% and 10 wt.%) present a good moisture resistance performance. Therefore, the SBS content should be seriously selected by considering the dry and wet conditions that are used to balance the adhesion property and debonding properties. The content of 4 wt.% may be the optimal content under the dry adhesion and moisture resistance.
Properties of CuFeS2/TiO2 Nanocomposite Prepared by Mechanochemical Synthesis
Authors: Dutkova Erika , Baláž Matej , Daneu Nina , Tatykayev Batukhan , Karakirova Yordanka , Velinov Nikolay , Kostova Nina , Briančin Jaroslav , Baláž Peter
Published: October 2022

CuFeS2/TiO2 nanocomposite has been prepared by a simple, low-cost mechanochemical route to assess its visible-light-driven photocatalytic efficiency in Methyl Orange azo dye decolorization. The structural and microstructural characterization was studied using X-ray diffraction and high-resolution transmission electron microscopy. The presence of both components in the composite and a partial anatase-to-rutile phase transformation was proven by X-ray diffraction. Both components exhibit crystallite size below 10 nm. The crystallite size of both phases in the range of 10–20 nm was found and confirmed by TEM. Surface and morphological properties were characterized by scanning electron microscopy and nitrogen adsorption measurement. Scanning electron microscopy has shown that the nanoparticles are agglomerated into larger grains. The specific surface area of the nanocomposite was determined to be 21.2 m2·g−1. Optical properties using UV-Vis and photoluminescence spectroscopy were also investigated. CuFeS2/TiO2 nanocomposite exhibits strong absorption with the determined optical band gap 2.75 eV. Electron paramagnetic resonance analysis has found two types of paramagnetic ions in the nanocomposite. Mössbauer spectra showed the existence of antiferromagnetic and paramagnetic spin structure in the nanocomposite. The CuFeS2/TiO2 nanocomposite showed the highest discoloration activity with a MO conversion of ~ 74% after 120 min irradiation. This study has shown the possibility to prepare nanocomposite material with enhanced photocatalytic activity of decoloration of MO in the visible range by an environmentally friendly manner
Experimental Study at the Phase Interface of a Single-Crystal Ni-Based Superalloy Using TEM
Authors: Zhang Hongye , Wen Huihui , Peng Runlai , He Ruijun , Li Miao , Feng Wei , Zhao Yao , Liu Zhanwei
Published: October 2022

The single-crystal Ni-based superalloys, which have excellent mechanical properties at high temperatures, are commonly used for turbine blades in a variety of aero engines and industrial gas turbines. Focusing on the phase interface of a second-generation single-crystal Ni-based superalloy, in-situ TEM observation was conducted at room temperature and high temperatures. Intensity ratio analysis was conducted for the measurement of two-phase interface width. The improved geometric phase analysis method, where the adaptive mask selection method is introduced, was used for the measurement of the strain field near the phase interface. The strained irregular transition region is consistent with the calculated interface width using intensity ratio analysis. An intensity ratio analysis and strain measurement near the interface can corroborate and complement each other, contributing to the interface structure evaluation. Using TEM in-situ heating and Fourier transform, the change of dislocation density in the γ phase near the two-phase interface of the single-crystal Ni-based superalloy was analyzed. The dislocation density decreases first with the increase in temperature, consistent with the characteristics of metal quenching, and increases sharply at 450 °C. The correlation between the variation of dislocation density at high temperatures and the intermediate temperature brittleness was also investigated.
Nonlinear Stability of Natural-Fiber-Reinforced Composite Cylindrical Shells with Initial Geometric Imperfection Considering Moisture Absorption and Hygrothermal Aging
Authors: Zhang Hongyu , Bai Haifeng , Zuo Zhongyi
Published: October 2022

In this paper, the nonlinear stability of a natural-fiber-reinforced composite cylindrical shell with initial geometric imperfection is investigated. The nonlinear governing equations are established by high-order shear deformation theory. The load-edge shortening curves for different imperfection amplitudes are obtained by the Galerkin method. Several numerical examples are presented to verify the accuracy of the proposed method and to investigate the influence of initial geometric imperfection, moisture absorption, and hygrothermal aging on the post-buckling behavior of natural-fiber-reinforced composite cylindrical shells.
Selective Etching of Si versus Si1−xGex in Tetramethyl Ammonium Hydroxide Solutions with Surfactant
Authors: Choi Yongjoon , Cho Choonghee , Yoon Dongmin , Kang Joosung , Kim Jihye , Kim So Young , Suh Dong Chan , Ko Dae-Hong
Published: October 2022

We investigated the selective etching of Si versus Si1−xGex with various Ge concentrations (x = 0.13, 0.21, 0.30, 0.44) in tetramethyl ammonium hydroxide (TMAH) solution. Our results show that the Si1−xGex with a higher Ge concentration was etched slower due to the reduction in the Si(Ge)–OH bond. Owing to the difference in the etching rate, Si was selectively etched in the Si0.7Ge0.3/Si/Si0.7Ge0.3 multi-layer. The etching rate of Si depends on the Si surface orientation, as TMAH is an anisotropic etchant. The (111) and (010) facets were formed in TMAH, when Si was laterally etched in the <110> and <100> directions in the multi-layer, respectively. We also investigated the effect of the addition of Triton X-100 in TMAH on the wet etching process. Our results confirmed that the presence of 0.1 vol% Triton reduced the roughness of the etched Si and Si1−xGex surfaces. Moreover, the addition of Triton to TMAH could change the facet formation from (010) to (011) during Si etching in the <100>-direction. The facet change could reduce the lateral etching rate of Si and consequently reduce selectivity. The decrease in the layer thickness also reduced the lateral Si etching rate in the multi-layer.
Effect of Exposure to Environmental Cycling on the Thermal Conductivity of Expanded Polystyrene
Authors: Petre Sergiu George , Isopescu Dorina Nicolina , Pruteanu Marian , Cojocaru Alexandra
Published: October 2022

The global effort to reduce energy consumption generated by buildings involves the increasing use of thermal insulation materials, with expanded polystyrene representing one of the most used materials to this end. The thermal performance of expanded polystyrene has been extensively studied; however, information on the effect of exposure to cyclic environmental conditions on its thermal performance is limited. Therefore, we conducted such a study, which is presented in this article. In the first stage, samples were subjected to 28 days of preconditioning to accelerate the increase in moisture in the material. The second stage involved exposure to 40 freeze–thaw cycles of 12 h each. The weight and thermal conductivity of the samples were measured before and after exposure, and the compression behavior was also analyzed. The results show a decrease in the thermal performance of expanded polystyrene exposed to cyclic environmental conditions, as demonstrated by an increase in the water content of the material under the same measurement conditions and an increase of 5.06% in the average thermal conductivity. The influence of this increase on the thermal performance of commonly used wall construction elements was also been studied and presented in this article. A decrease of 7.59% in the compressive stress of the material at 10% strain was also demonstrated.
Effect of Drilling Parameters on Machining Performance in Drilling Polytetrafluoroethylene
Authors: Ni Jing , Zeng Xiaotian , Al-Furjan M. S. H. , Zhao Huijun , Guan Liming , Cui Zhi , Han Lidong
Published: October 2022

Polytetrafluoroethylene (PTFE) plays an important role in semiconductor manufacturing. It is an important processing material for the key sealing components in the field of immersion lithography. The lack of research related to the mechanical processing of PTFE leads to many challenges in producing complex parts. This paper conducted a drilling experiment on PTFE. The effect of cutting parameters on the drilling performance was investigated. Thrust, torque, surface roughness, and drilling temperature were used to evaluate the influence of cutting parameters on drilling performance. In addition, the empirical mathematical models of thrust and torque were developed using analysis of variance (ANOVA). The results indicated that the spindle speed had the most important effect on the thrust and the feed rate had the most significant effect on the torque. The lowest values of thrust and torque were, respectively, 22.64 N and 0.12 Nm, achieved in the case of spindle speed of 5000 rev/min, and feed rate of 50 mm/min. The surface quality is also best at this cutting parameter. Studies have shown that higher spindle speeds with lower feed rates are ideal parameters for improving the drilling performance and machining quality of PTFE. In addition, it was found that the temperature differences due to different drilling depths were related to chip accumulation. Surface roughness inconsistencies at various locations in the inner wall of the hole were influenced by chip adhesion during machining. This paper provides a suggestion for optimizing cutting parameters and hole quality.
Essential Oils as Antimicrobial Active Substances in Wound Dressings
Authors: Gheorghita Daniela , Grosu Elena , Robu Alina , Ditu Lia , Deleanu Iuliana , Gradisteanu Pircalabioru Gratiela , Raiciu Anca-Daniela , Bita Ana-Iulia , Antoniac Aurora , Antoniac Vasile
Published: October 2022

Wound dressings for skin lesions, such as bedsores or pressure ulcers, are widely used for many patients, both during hospitalization and in subsequent treatment at home. To improve the treatment and shorten the healing time and, therefore, the cost, numerous types of wound dressings have been developed by manufacturers. Considering certain inconveniences related to the intolerance of some patients to antibiotics and the antimicrobial, antioxidant, and curative properties of certain essential oils, we conducted research by incorporating these oils, based on polyvinyl alcohol/ polyvinyl pyrrolidone (PVA/PVP) biopolymers, into dressings. The objective of this study was to study the potential of a polymeric matrix for wound healing, with polyvinyl alcohol as the main material and polyvinyl pyrrolidone and hydroxypropyl methylcellulose (HPMC) as secondary materials, together with additives (plasticizers poly(ethylene glycol) (PEG) and glycerol), stabilizers (Zn stearate), antioxidants (vitamin A and vitamin E), and four types of essential oils (fennel, peppermint, pine, and thyme essential oils). For all the studied samples, the combining compatibility, antimicrobial, and cytotoxicity properties were investigated. The obtained results demonstrated a uniform morphology for almost all the samples and adequate barrier properties for contact with suppurating wounds. The results show that the obtained samples containing essential oils have a good inhibitory effect on, or antimicrobial properties against, Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231. The MTT assay showed that the tested samples were not toxic and did not lead to cell death. The results showed that the essential oils used provide an effective solution as active substances in wound dressings.
OFF-State Leakage Suppression in Vertical Electron–Hole Bilayer TFET Using Dual-Metal Left-Gate and N+-Pocket
Authors: Liu Hu , Zhang Wenting , Wang Zaixing , Li Yao , Zhang Huawei
Published: October 2022

In this paper, an In0.53Ga0.47As electron–hole bilayer tunnel field-effect transistor (EHBTFET) with a dual-metal left-gate and an N+-pocket (DGNP-EHBTFET) is proposed and systematically studied by means of numerical simulation. Unlike traditional transverse EHBTFETs, the proposed DGNP-EHBTFET can improve device performance without sacrificing the chip density, and can simplify the manufacturing process. The introduction of the dual-metal left-gate and the N+-pocket can shift the point-tunneling junction and adjust the energy band and the electric field in it, aiming to substantially degrade the OFF-state current (IOFF) and maintain good ON-state performance. Moreover, the line tunneling governed by the tunneling-gate and the right-gate can further regulate and control IOFF. By optimizing various parameters related to the N+-pocket and the gate electrodes, DGNP-EHBTFET’s IOFF is reduced by at least four orders of magnitude, it has a 75.1% decreased average subthreshold swing compared with other EHBTFETs, and it can maintain a high ON-state current. This design greatly promotes the application potential of EHBTFETs.
Evaluation of the Cathodic Electrodeposition Effectiveness of the Hydroxyapatite Layer Used in Surface Modification of Ti6Al4V-Based Biomaterials
Authors: Ehlert Michalina , Radtke Aleksandra , Bartmański Michał , Piszczek Piotr
Published: October 2022

The important issue associated with the design and the fabrication of the titanium and titanium alloy implants is the increase of their biointegration with bone tissue. In the presented paper, the research results concerning the conditions used in the cathodic deposition of hydroxyapatite on the surface Ti6Al4V substrates primarily modified by the production of TiO2 nanoporous coatings, TiO2 nanofibers, and titanate coatings, are discussed. Despite excellent biocompatibility with natural bone tissue of materials based on hydroxyapatite (HA), their poor adhesion to the substrate caused the limited use in the implants’ construction. In our works, we have focused on the comparison of the structure, physicochemical, and mechanical properties of coating systems produced at different conditions. For this purpose, scanning electron microscopy images, chemical composition, X-ray diffraction patterns, infrared spectroscopy, wettability, and mechanical properties are analyzed. Our investigations proved that the intermediate titanium oxide coatings presence significantly increases the adhesion between the hydroxyapatite layer and the Ti6Al4V substrate, thus solving the temporary delamination problems of the HA layer.
Influence of Constant Magnetic Field upon Fatigue Life of Commercially Pure Titanium
Authors: Aksenova Krestina , Zaguliaev Dmitrii , Konovalov Sergey , Shlyarov Vitalii , Ivanov Yurii
Published: October 2022

Cyclic tests of the multicycle fatigue of commercially pure titanium were performed under normal conditions (without a magnetic field) and after exposure to a constant magnetic field of varying density (B = 0.3, 0.4, 0.5 T). It was shown that the application of the constant magnetic field of varying density led to a fold increase in the average number of cycles to destruction of the VT1-0 titanium samples by 64, 123, and 163%, respectively. Scanning electron microscopy revealed that the magnetic field led to a 1.45-fold increase in the critical length of the fracture (the width of the fatigue crack growth zone) and a 1.6-fold decrease in the distance between the fatigue striations in the accelerated crack growth zone of the destroyed titanium samples. It was established that a subgrain (fragmented) structure formed in the area of the fatigue growth of the fracture of the titanium samples. The size of the subgrains corresponded to the spaces between the fatigue striations, which had an inhibitory influence on the microcrack propagation. Collectively, the revealed facts are indicative of a higher material resistance to fatigue fracture propagation and increased operation resources under the fatigue tests in the magnetic field, which correlates with the data on the growth of the average number of cycles to fracture of the VT1-0 titanium samples.
Fatigue and Fracture Resistance Testing of Polyether Ether Ketone (PEEK) Implant Abutments in an Ex Vivo Chewing Simulator Model
Authors: Saravi Babak , Flohr Anselm , Patzelt Sebastian B. , Spies Benedikt C. , Hazard Derek , Kohal Ralf J.
Published: October 2022

Polyether ether ketone (PEEK) has been introduced into implant dentistry as a viable alternative to current implant abutment materials. However, data on its physico-mechanical properties are still scarce. The present study sought to shed light on this topic utilizing an ex vivo chewing simulator model. A total of 48 titanium two-piece implants were allocated into three groups (n = 16 per group): (1) implants with PEEK abutments and an internal butt-joint connection (PBJ), (2) implants with PEEK abutments and an internal conical implant–abutment connection (PC), and (3) implants with zirconia abutments and an internal butt-joint connection (ZA). All abutments were restored with a non-precious metal alloy crown mimicking the upper right central incisor. A dynamic chewing simulation of half (n = 8) of the specimens per group was performed with 5 × 106 cycles and a load of 49 N at a frequency of 1.7 Hz with thermocycling between 5 and 55 °C. The other eight specimens served as unloaded controls. Surface roughness, implant–abutment connection microgaps (IACMs), and the titanium base–abutment interface microgaps (TAIMs) in the loaded groups were evaluated. Finally, a quasi-static loading test was performed in a universal testing machine with all samples to evaluate fracture resistance. Overall, 23 samples survived the artificial chewing process. One abutment screw fracture was observed in the PC group. The ZA group showed higher surface roughness values than PEEK abutments. Furthermore, ZA revealed lower TAIM values compared to PEEK abutments. Similarly, ZA was associated with lower IACM values compared to PBJ. Fracture loads/bending moments were 1018 N/704 N cm for PBJ, 966 N/676 N cm for PC, and 738 N/508 N cm for ZA, with no significant differences compared to the unloaded references. Artificial loading did not significantly affect fracture resistance of the examined materials. PEEK abutments were associated with better load-bearing properties than zirconia abutments, although they showed higher microgap values. PEEK abutments could, therefore, be feasible alternatives to zirconia abutments based on the present ex vivo findings resembling 20 years of clinical service.
Data-Driven Techniques for Evaluating the Mechanical Strength and Raw Material Effects of Steel Fiber-Reinforced Concrete
Authors: Al-Hashem Mohammed Najeeb , Amin Muhammad Nasir , Ahmad Waqas , Khan Kaffayatullah , Ahmad Ayaz , Ehsan Saqib , Al-Ahmad Qasem M. S. , Qadir Muhammad Ghulam
Published: October 2022

Estimating concrete properties using soft computing techniques has been shown to be a time and cost-efficient method in the construction industry. Thus, for the prediction of steel fiber-reinforced concrete (SFRC) strength under compressive and flexural loads, the current research employed advanced and effective soft computing techniques. In the current study, a single machine learning method known as multiple-layer perceptron neural network (MLPNN) and ensembled machine learning models known as MLPNN-adaptive boosting and MLPNN-bagging are used for this purpose. Water; cement; fine aggregate (FA); coarse aggregate (CA); super-plasticizer (SP); silica fume; and steel fiber volume percent (Vf SF), length (mm), and diameter were the factors considered (mm). This study also employed statistical analysis such as determination coefficient (R2), root mean square error (RMSE), and mean absolute error (MAE) to assess the performance of the algorithms. It was determined that the MLPNN-AdaBoost method is suitable for forecasting SFRC compressive and flexural strengths. The MLPNN technique’s higher R2, i.e., 0.94 and 0.95 for flexural and compressive strength, respectively, and lower error values result in more precision than other methods with lower R2 values. SHAP analysis demonstrated that the volume of cement and steel fibers have the greatest feature values for SFRC’s compressive and flexural strengths, respectively.
High-Performance Lithium-Ion Storage of FeTiO3 with Morphology Adjustment and Niobium Doping
Authors: Li Shenghao , Wang Xiaohuan , Shi Zhiming , Wang Jun , Ji Guojun , Yaer Xinba
Published: October 2022

Ferrous titanate (FeTiO3) has a high theoretical capacity and physical and chemical properties stability, so it is a potential lithium anode material. In this study, FeTiO3 nanopowder and nanosheets were prepared by the sol–gel method and the hydrothermal method. In addition, niobium-ion doping was carried out, the radius of Nb close to Ti so the Nb can easily enter into the FeTiO3 lattice. Nb can provide more free electrons to improve the electrochemical performance. Then, the effects of the morphology and niobium doping on the microstructure and electrochemical properties of FeTiO3 were systematically studied. The results show that FeTiO3 nanosheets have a better lithium storage performance than nanopowders because of its high specific surface area. A certain amount of niobium doping can improve the electrochemical performance of FeTiO3. Finally, a 1 mol% niobium-doping FeTiO3 nanosheets (1Nb-FTO-S) electrode provided a higher specific capacity of 782.1 mAh g−1 at 50 mA g−1. After 200 cycles, the specific capacity of the 1Nb-FTO-S electrode remained at 509.6 mAh g−1. It is revealed that an increased specific surface area and ion doping are effective means to change the performance of lithium, and the proposed method looks promising for the design of other inorganic oxide electrode materials.
Three-Point Bending Behavior of Aluminum Foam Sandwich with Different Interface Bonding Methods
Authors: Huang Peng , Sun Xi , Su Xixi , Gao Qiang , Feng Zhanhao , Zu Guoyin
Published: October 2022

The interface bonding method has a great influence on the mechanical properties of aluminum foam sandwich (AFS). This study aims to investigate the effect of different interface bonding methods on the mechanical properties of AFS. In this paper, the metallurgical-bonding interface-formation mechanism of AFS prepared by powder metallurgy was investigated. The shear properties of metallurgical-bonded AFS were determined by the panel peeling test. The flexural properties and energy absorption of metallurgical-bonded and glued AFS were analyzed through the three-point bending test. The results show that the magnesium, silicon, and copper elements of the core layer diffuse to panels and form a metallurgical composite layer. The metallurgical-bonding strength between the panel and core layer is higher than that of the foam core layer. The peak load of metallurgically-bonded AFS is 24% more than that of glued AFS, and energy absorption is 12.2 times higher than that of glued AFS.
Characterization of Synovial Fluid Components: Albumin-Chondroitin Sulfate Interactions Seen through Molecular Dynamics
Authors: Kruszewska Natalia , Mazurkiewicz Adam , Szala Grzegorz , Słomion Małgorzata
Published: October 2022

The friction coefficient of articular cartilage (AC) is very low. A method of producing tailor-made materials with even similar lubrication properties is still a challenge. The physicochemical reasons for such excellent lubrication properties of AC are still not fully explained; however, a crucial factor seems to be synergy between synovial fluid (SF) components. As a stepping stone to being able to produce innovative materials characterized by a very low friction coefficient, we studied the interactions between two important components of SF: human serum albumin (HSA) and chondroitin sulfate (CS). The molecular dynamics method, preceded by docking, is used in the study. Interactions of HSA with two types of CS (IV and VI), with the addition of three types of ions often found in physiological solutions: Ca2+, Na+, and Mg2+, are compared. It was found that there were differences in the energy of binding values and interaction maps between CS-4 and CS-6 complexes. HSA:CS-4 complexes were bound stronger than in the case of HSA:CS-6 because more interactions were formed across all types of interactions except one—the only difference was for ionic bridges, which were more often found in HSA:CS-6 complexes. RMSD and RMSF indicated that complexes HSA:CS-4 behave much more stably than HSA:CS-6. The type of ions added to the solution was also very important and changed the interaction map. However, the biggest difference was caused by the addition of Ca2+ ions which were prone to form ionic bridges.
New 5-Aminotetrazole-Based Energetic Polymers: Synthesis, Structure and Properties
Authors: Sukhanov Gennady T. , Bosov Konstantin K. , Filippova Yulia V. , Sukhanova Anna G. , Krupnova Irina A. , Pivovarova Ekaterina V.
Published: October 2022

An N-glycidyl-5-aminotetrazole homopolymer was synthesized herein by nucleophilic substitution of 5-aminotetrazole heterocycles for chlorine atoms in poly-(epichlorohydrin)-butanediol. Copolymers of N-glycidyl-5-aminotetrazole and glycidyl azide with a varied ratio of energetic elements were synthesized by simultaneously reacting the 5-aminotetrazole sodium salt and the azide ion with the starting polymeric matrix. The 5-aminotetrazole-based homopolymer was nitrated to furnish a polymer whose macromolecule is enriched additionally with energy-rich terminal ONO2 groups and nitrate anions. The structures of the synthesized polymers were characterized by 1H and 13C NMR and IR spectroscopies, elemental analysis and gel-permeation chromatography. The densities were experimentally measured, and thermal stability data were acquired by differential scanning calorimetry. The insertion of aminotetrazole heterocycles into the polymeric chain and their modification via nitration provides an acceptable thermal stability and a considerable enhancement in density and nitrogen content compared to azide homopolymer GAP. By the 1.3-dipolar cycloaddition reaction, we demonstrated the conceptual possibility of preparing spatially branched, energy-rich polymeric binders bearing 5-aminotetrazole and 1,2,3-triazole heterocycles starting from the plasticized azide copolymers. The presence of the aforesaid advantages makes the reported polymers attractive candidates for use as a scaffold of energetic binders.
Adsorption Study of Continuous Heavy Metal Ions (Pb2+, Cd2+, Ni2+) Removal Using Cocoa (Theobroma cacao L.) Pod Husks
Authors: Tejada-Tovar Candelaria , Villabona-Ortíz Angel , González-Delgado Ángel
Published: October 2022

The serious toxicological effects of heavy metal ions in aquatic ecosystems have motivated the search for alternatives to reduce contamination of water sources from industrial wastewater. In this work, continuous adsorption of nickel, cadmium, and lead was assessed using a packed bed column filled with Cocoa (Theobroma cacao L.) pod husks widely available in the northern region of Colombia. The physicochemical characterization of the agricultural biomass was performed to quantify its chemical composition by bromatological, FT-IR, and energy-dispersive X-ray spectroscopy (EDS). The breakthrough curves were constructed for all heavy metal ions with bed depth of 4 and 7.5 cm, taking aliquots at 10, 30, 60, 90, 120, 150, 180, 210, 240, and 270 min. Moreover, experimental data were fitted to adsorption models in continuous mode to predict adsorptive performance (Adams–Bohart, Thomas, and Yoon–Nelson). For the FT-IR analysis of biomass before and after adsorption, the most representative bands occur around 3200–3900 cm−1 attributed to the presence of hydroxyl groups, showing the destruction of the peaks of lignocellulosic materials. The breakthrough curves revealed that for a 7.5 cm bed, adsorption performance reported the following order of promising results: Pb2+ > Ni2+ > Cd2+; while for a 4 cm bed, Pb2+ > Ni2+. The mechanism of adsorption of the evaluated metals onto cocoa pod husk was attributed to cationic exchange and microprecipitation due to the presence of Ca, K, and Si in the structure of the bio-adsorbent. Finally, the continuous adsorption was modeled under the mathematical expressions of Adams–Bohart, Thomas, and Yoon–Nelson reporting good fitting with correlation coefficient above 0.95.
Sensitivity of Compressed Composite Channel Columns to Eccentric Loading
Authors: Wysmulski Pawel , Debski Hubert , Falkowicz Katarzyna
Published: October 2022

This study investigated short thin-walled channel columns made of carbon/epoxy laminate. Columns with two multi-ply composite layups [0/45/−45/90]s and [90/−45/45/0]s were tested, with each layup having eight plies symmetric to the midplane. The columns were subjected to compressive loads, including an eccentric compressive load applied relative to the center of gravity of their cross-section. Simple support boundary conditions were applied to the ends of the columns. The scope of the study included analyzing the effect of load eccentricity on the buckling mode, bifurcation load (idealized structure), and critical load (structure with initial imperfections). The critical load for the actual structure was determined with the use of approximation methods, based on experimental postbuckling equilibrium paths. In parallel with the experiments, a numerical analysis was conducted using the finite element method and Abaqus® software (Dassault Systèmes, Vélizy-Villacoublay, France). The first stage of the numerical analysis consisted of solving an eigenproblem, in order to determine the mode of the loss of structural stability and to calculate the bifurcation loads for structures under axial and eccentric compression. The second stage of the numerical analysis involved examining the non-linear state of pre-deflected structures. Numerical postbuckling equilibrium paths were used to estimate the critical loads with an approximation method. The experimental results were used to validate the numerical models. This made it possible to determine the effect of compressive load eccentricity on the buckling mode and critical load of the tested structures. The results confirmed that compressive load eccentricity had a significant impact on the load-carrying capacity in the postbuckling range. This may potentially lead to premature damage to composite materials and, ultimately, to a reduced load-carrying capacity of structures.
Synthesis and Characterization of Porous Forsterite Ceramics with Prospective Tissue Engineering Applications
Authors: Alecu Andrada Elena , Balaceanu Gabriel-Costin , Nicoara Adrian Ionut , Neacsu Ionela Andreea , Busuioc Cristina
Published: October 2022

Due to the urgent need to develop and improve biomaterials, the present article proposes a new strategy to obtain porous scaffolds based on forsterite (Mg2SiO4) for bone tissue regeneration. The main objective is to restore and improve bone function, providing a stable environment for regeneration. The usage of magnesium silicate relies on its mechanical properties being superior to hydroxyapatite and, in general, to calcium phosphates, as well as its high biocompatibility, and antibacterial properties. Mg2SiO4 powder was obtained using the sol-gel method, which was calcinated at 800 °C for 2 h; then, part of the powder was further used to make porous ceramics by mixing it with a porogenic agent (e.g., sucrose). The raw ceramic bodies were subjected to two sintering treatments, at 1250 or 1320 °C, and the characterization results were discussed comparatively. The porogenic agent did not influence the identified phases or the samples’ crystallinity and was efficiently removed during the heat treatment. Moreover, the effect of the porogenic agent no longer seems significant after sintering at 1250 °C; the difference in porosity between the two ceramics was negligible. When analysing the in vitro cytotoxicity of the samples, the ones that were porous and treated at 1320 °C showed slightly better cell viability, with the cells appearing to adhere more easily to their surface.
The Efficiency Improvement of Multiple Receivers in Wireless Power Transmission by Integrating Metasurfaces
Authors: Xun Jian-Hui , Mu Yajie , Zhang Kunyi , Liu Haixia , Li Long
Published: October 2022

In this paper, we propose the use of metasurfaces to enhance evanescent wave coupling to improve the wireless power transfer (WPT) efficiency of multiple receivers. A 4 × 4 negative permeability metasurface is designed and placed between the transmitter (Tx) and receiver (Rx) coils for the greatest improvement in transfer efficiency. Through the analysis of the number and position topologies of Rx coils, the efficiency can be greatly improved; the maximum efficiency at longer transmission distances is achieved through the 4 × 4 negative permeability metasurface in the multiple−receiver system. We show with simulation and measurement results that the power transfer efficiency of the system can be improved significantly by integrating metasurfaces. The maximum transfer efficiency is achieved in a multiple−receiver WPT system when the number and topology of Rx coils is case 0 of single transmitter−three receivers (STTR). The results show that the total efficiency of the multiple receivers WPT system can be as high as 97%.
Study on the Mechanical Properties of Perforated Steel Plate Reinforced Concrete
Authors: Li Chunbao , Li Gaojie , Zheng Liang , Liu Xiaohui , Li Shen , Wang Xukai , Soloveva Valentina Y. , Dalerjon Hojiboev , Fan Zhiguang , Qin Pengju
Published: October 2022

In this paper, the mechanical properties of perforated steel plate reinforced concrete were studied. Through the compression test of the specimen, the failure mode, the compressive ultimate bearing capacity, and the stress–strain curve of the specimen were obtained. The results show that the compressive strength of perforated steel plate reinforced concrete is twice that of the same grade of plain concrete; through the pull-out test of the specimen, the failure mode and the ultimate uplift bearing capacity were obtained. The finite element software ANSYS was used to simulate the perforated steel plate reinforced concrete specimen, and the results show that the model is reliable. Through the range analysis method, the influence degree of the three factors of the thickness of the perforated steel plate, the hole diameter, and the hole spacing on the compressive strength and the ultimate bearing capacity of the pull-out was studied, and the optimal solution was obtained. The analysis results show that the order of the three factors on the compression and pull-out tests is: the plate thickness of the perforated steel plate > the hole diameter > the hole spacing; the optimal combination of the compressive strength of the perforated steel plate reinforced concrete specimen is that the thickness of the perforated steel plate is 0.75 mm, the diameter of the perforated steel plate is 15 mm, and the spacing of the perforated steel plate is 5 mm; the optimal combination of the ultimate bearing capacity of the pull-out is that the thickness of the steel plate with holes is 1.0 mm, the diameter of the steel plate with holes is 15 mm, and the spacing of the steel plate with holes is 15 mm.
The Influence of Surface Texturing of Ceramic and Superhard Cutting Tools on the Machining Process—A Review
Authors: Grigoriev Sergey N. , Soe Thet Naing , Hamdy Khaled , Pristinskiy Yuri , Malakhinsky Alexander , Makhadilov Islamutdin , Romanov Vadim , Kuznetsova Ekaterina , Podrabinnik Pavel , Kurmysheva Alexandra Yu. , Smirnov Anton , Solís Pinargote Nestor Washington
Published: October 2022

Machining is an indispensable manufacturing process for a wide range of engineering materials, such as metals, ceramics, and composite materials, in which the tool wear is a serious problem, which affects not only the costs and productivity but also the quality of the machined components. Thus, the modification of the cutting tool surface by application of textures on their surfaces is proposed as a very promising method for improving tool life. Surface texturing is a relatively new surface engineering technology, where microscale or nanoscale surface textures are generated on the cutting tool through a variety of techniques in order to improve tribological properties of cutting tool surfaces by reducing the coefficient of friction and increasing wear resistance. In this paper, the studies carried out to date on the texturing of ceramic and superhard cutting tools have been reviewed. Furthermore, the most common methods for creating textures on the surfaces of different materials have been summarized. Moreover, the parameters that are generally used in surface texturing, which should be indicated in all future studies of textured cutting tools in order to have a better understanding of its effects in the cutting process, are described. In addition, this paper proposes a way in which to classify the texture surfaces used in the cutting tools according to their geometric parameters. This paper highlights the effect of ceramic and superhard textured cutting tools in improving the machining performance of difficult-to-cut materials, such as coefficient of friction, tool wear, cutting forces, cutting temperature, and machined workpiece roughness. Finally, a conclusion of the analyzed papers is given.
Inelastic Deformation of Coronary Stents: Two-Level Model
Authors: Volegov Pavel S. , Knyazev Nikita A. , Gerasimov Roman M. , Silberschmidt Vadim V.
Published: October 2022

This study describes the internal structure of materials used to produce medical stents. A two-level elastoviscoplastic mathematical model, which sets the parameters and describes the processes at the grain level, was developed and numerically implemented. A separate study was conducted to identify the most dangerous deformation modes in the balloon-expandable stent placement using the finite-element method in COMSOL Multiphysics. As a result, the challenging strain state type required for setting the kinematic loading on a representative macrovolume in the two-level model was obtained. A yield surface for different deformation paths in the principal deformation space for stainless steel AISI 316L was obtained and the effect of grain size on the deformation behavior of this material was explored using the developed model.
Influence of Grain Orientation and Grain Boundary Features on Local Stress State of Cu-8Al-11Mn Alloy Investigated Using Crystal Plasticity Finite Element Method
Authors: Zheng Ce , Xu Lijun , Feng Xiaohui , Huang Qiuyan , Li Yingju , Zhang Zhongwu , Yang Yuansheng
Published: October 2022

Reducing the local stress in the vicinity of the grain boundaries is a favorable way to improve the super-elastic properties of super-elastic alloys. The crystal plasticity finite element method (CPFEM) was applied in this study to simulate the deformation behavior and local stress of a super-elastic Cu-8Al-11Mn (wt.%) alloy containing single grains with various orientations, columnar grains with different misorientation angles, and tri-crystals with distinct grain boundary morphologies. The results indicated that the stress distribution of single grains presented obvious orientation dependence during deformation. Uniformly distributed stress was observed in grains with orientations of 0° and 90° when more slip systems were activated during deformation. With the increase in the misorientation angles of columnar grains, the stresses in the vicinity of the grain boundaries increased, which was related to the difference in the shear stress of the slip systems in adjacent grains. When the difference in the shear stress of the slip systems in two adjacent grains was large, a local stress concentration formed in the vicinity of the grain boundary. Compared with the triple-junction grain boundaries, the local stresses of the straight and vertical grain boundaries were smaller, which was closely related to the number of activated slip systems on both sides of the grain boundary. The above results were obtained experimentally and could be used to design super-elastic alloys with high performance.
Magnetic Structure of Wiegand Wire Analyzed by First-Order Reversal Curves
Authors: Jiang Liang , Yang Chao , Song Zenglu , Takemura Yasushi
Published: October 2022

Various coercive force field components in Wiegand wire exhibit a significant magnetization reversal under an applied magnetic field. A fast magnetization reversal is accompanied by a large Barkhausen jump, which induces a pulse voltage in a pickup coil wound around the Wiegand wire which serves as a power source for the devices or sensors. This study aims to elucidate the magnetization reversal in the Wiegand wire by using a first-order reversal curve (FORC) diagram method. The magnetic structure of the Wiegand wire typically comprises three layers: a soft layer, middle layer, and hard layer. In this study, we analyze the coercive and interactive force fields between the adjacent layers. The results demonstrate a high coercivity of the center core and a lower coercivity of the outer layer of the wire.
Novel Approaches and Biomaterials for Bone Tissue Engineering: A Focus on Silk Fibroin
Authors: Paladini Federica , Pollini Mauro
Published: October 2022

Bone tissue engineering (BTE) represents a multidisciplinary research field involving many aspects of biology, engineering, material science, clinical medicine and genetics to create biological substitutes to promote bone regeneration. The definition of the most appropriate biomaterials and structures for BTE is still a challenge for researchers, aiming at simultaneously combining different features such as tissue generation properties, biocompatibility, porosity and mechanical strength. In this scenario, among the biomaterials for BTE, silk fibroin represents a valuable option for the development of functional devices because of its unique biological properties and the multiple chances of processing. This review article aims at providing the reader with a general overview of the most recent progresses in bone tissue engineering in terms of approaches and materials with a special focus on silk fibroin and the related mechanisms involved in bone regeneration, and presenting interesting results obtained by different research groups, which assessed the great potential of this protein for bone tissue engineering.
Solvothermal Synthesis, Structural Characterization and Optical Properties of Pr-Doped CeO2 and Their Degradation for Acid Orange 7
Authors: Xu Yaohui , Wu Pingkeng , Wu Mingjin , Gu Yuehe , Yu Hongguang , Ding Zhao
Published: October 2022

Pr-doped CeO2 with different doping levels was prepared from Ce(NO3)3∙6H2O and Pr(NO3)3∙6H2O by solvothermal method without any additional reagents, in which the mixed solution of ethylene glycol and distilled water was employed as a solvent. The influences of Pr-doping on phase composition, crystal structure and morphology were investigated, as well as Pr valence and oxygen vacancy defects. The Pr cations entered into the CeO2 crystal lattice with normal trivalence and formed a Pr-CeO2 solid solution based on the fluorite structure. The larger trivalent Pr was substituted for tetravalent Ce in the CeO2 crystal and compensated by oxygen vacancy defects, which caused the local lattice expansion of the crystal lattice. Moreover, the Pr-doped CeO2 solid solutions exhibited visible color variation from bright cream via brick red to dark brown with the increasing of Pr contents. The degradation of AO7 dye was also investigated using a domestic medical ultraviolet lamp; the removal efficiency of AO7 by 1% and 2% Pr-doped CeO2 approached 100%, much higher than 66.2% for undoped CeO2.
Estimation of Average Grain Size from Microstructure Image Using a Convolutional Neural Network
Authors: Jung Jun-Ho , Lee Seok-Jae , Kim Hee-Soo
Published: October 2022

In this study, the average grain size was evaluated from a microstructure image using a convolutional neural network. Since the grain size in a microstructure image can be directly measured and verified in the original image, unlike the chemical composition or mechanical properties of material, it is more appropriate to validate the training results quantitatively. An analysis of microstructure images, such as grain size, can be performed manually or using image analysis software; however, it is expected that the analysis would be simpler and faster with machine learning. Microstructure images were created using a phase-field simulation, and machine learning was carried out with a convolutional neural network model. The relationship between the microstructure image and the average grain size was not judged by classification, as the goal was to have different results for each microstructure using regression. The results showed high accuracy within the training range. The average grain sizes of experimental images with explicit grain boundary were well estimated by the network. The mid-layer image was analyzed to examine how the network understood the input microstructure image. The network seemed to recognize the curvatures of the grain boundaries and estimate the average grain size from these curvatures.
Mechanical Property Evaluation and Prediction of Cementing Composites Blended with MK and UFA under High-Temperature Steam Curing
Authors: Liang Chao , Xing Yongming , Hou Xiaohu
Published: October 2022

In this paper, the influence of the substitution rate of metakaolin (MK) and ultrafine fly ash (UFA) on the hydration degree, the micromechanical properties, the pore size distribution, and the corresponding fractal dimension of composite cement-based material was investigated under high-temperature steam curing. Furthermore, Thermogravimetric, Nanoindentation, and low-field nuclear magnetic resonance tests were used to explore the influencing factors of pore size distribution and its corresponding multi-fractal dimension. Finally, the correlations among the pore size distribution, related fractal dimensions, and compression strength were analyzed. Results indicate that the MK-UFA cement ternary cementation system (TCS) can improve the compressive strength and fluidity of samples and enhance the hydration degree and micromechanical properties of the cementitious system. TCS effectively refines the pore size and increases microporosity. In addition, micropore and its fractal dimension have a stronger correlation with the compressive strength of composite cement-based materials. Furthermore, the micro-fractal dimensions can better reflect the essential characteristics of the composite cementitious system. The higher the degree of hydration of the cementitious system and the nanomechanical properties of the C-(A)-S-H gel, the lower the micro-fractal dimension. Finally, the GM (1,3) prediction model of compressive strength, micro-fractal dimension, and microporosity are established based on the grey relational theory.