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Materials, Volume 15, Issue 18 (September-2 2022) – 321 articles

Cover Story (view full-size image): Polytetrafluoroethylene (PTFE) is considered an outstanding candidate for use as a dielectric medium for high-frequency devices due to its excellent dielectric properties and stability versus frequency, and it can meet the pressing demand for the rapidly developing modern information industry. Although PTFE has excellent dielectric properties at a high frequency, its high thermal expansion coefficient, low thermal conductivity, and poor mechanical properties limit its application in electronic devices. These deficits could be overcome by making PTFE-based composites with fillers to modify the matrix’s thermal, mechanical, and dielectric properties. View this paper
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14 pages, 8454 KiB  
Article
Hydrogen-Induced Dislocation Nucleation and Plastic Deformation of 001 and 11¯0 Grain Boundaries in Nickel
by Jiaqing Li, Ziyue Wu, Lin Teng, Guanyu Deng, Rui Wang, Cheng Lu, Weidong Li, Xin Huang and Yu Liu
Materials 2022, 15(18), 6503; https://doi.org/10.3390/ma15186503 - 19 Sep 2022
Cited by 3 | Viewed by 1999
Abstract
The grain boundary (GB) plays a crucial role in dominating hydrogen-induced plastic deformation and intergranular failure in polycrystal metals. In the present study, molecular dynamics simulations were employed to study the effects of hydrogen segregation on dislocation plasticity of a series of symmetrical [...] Read more.
The grain boundary (GB) plays a crucial role in dominating hydrogen-induced plastic deformation and intergranular failure in polycrystal metals. In the present study, molecular dynamics simulations were employed to study the effects of hydrogen segregation on dislocation plasticity of a series of symmetrical tilt grain boundaries (STGBs) with various hydrogen concentrations. Our study shows that hydrogen both enhances and reduces dislocation nucleation events from STGBs, depending on different GB structures. Specifically, for 001 STGBs, hydrogen does not affect the mode of heterogeneous dislocation nucleation (HDN), but facilitates nucleation events as a consequence of hydrogen disordering the GB structure. Conversely, hydrogen retards dislocation nucleation due to the fact that hydrogen segregation disrupts the transformation of boundary structure such as Σ9 (2 2 1¯) 11¯0 STGB. These results are helpful for deepening our understanding of GB-mediated hydrogen embrittlement (HE) mechanisms. Full article
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15 pages, 5552 KiB  
Article
Research on the Corrosion Behavior of Q235 Pipeline Steel in an Atmospheric Environment through Experiment
by Shuo Cai, Hongchao Ji, Fengyun Zhu, Weichi Pei, Wenchao Xiao and Xuefeng Tang
Materials 2022, 15(18), 6502; https://doi.org/10.3390/ma15186502 - 19 Sep 2022
Cited by 11 | Viewed by 1890
Abstract
Low-carbon steel pipelines are frequently used as transport pipelines for various media. As the pipeline transport industry continues to develop in extreme directions, such as high efficiency, long life, and large pipe diameters, the issue of pipeline reliability is becoming increasingly prominent. This [...] Read more.
Low-carbon steel pipelines are frequently used as transport pipelines for various media. As the pipeline transport industry continues to develop in extreme directions, such as high efficiency, long life, and large pipe diameters, the issue of pipeline reliability is becoming increasingly prominent. This study selected Q235 steel, a typical material for low-carbon steel pipelines, as the research object. In accordance with the pipeline service environment and the accelerated corrosion environment test spectrum, cyclic salt spray accelerated corrosion tests that simulated the effects of the marine atmosphere were designed and implemented. Corrosion properties, such as corrosion weight loss, morphology, and product composition of samples with different cycles, were characterized through appearance inspection, scanning electron microscopy analysis, and energy spectrum analysis. The corrosion behavior and mechanism of Q235 low-carbon steel in the enhanced corrosion environment were studied, and the corrosion weight loss kinetics of Q235 steel was verified to conform to the power function law. During the corrosion process, the passivation film on the surface of the low-carbon steel and the dense and stable α-FeOOH layer formed after the passivation film was peeled off played a role in corrosion resistance. The passivation effect, service life, and service limit of Q235 steel were studied and determined, and an evaluation model for quick evaluation of the corrosion life of Q235 low-carbon steel was established. This work provides technical support to improve the life and reliability of low-carbon steel pipelines. It also offers a theoretical basis for further research on the similitude and relevance of cyclic salt spray accelerated corrosion testing. Full article
(This article belongs to the Special Issue Advances in Metal Cutting, Casting, Forming and Heat Treatment)
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12 pages, 8468 KiB  
Article
On the Microstructure, Residual Stress and Fatigue Performance of Laser Metal Deposited TC17 Alloy Subjected to Laser Shock Peening
by Zhibin An, Weifeng He, Xin Zhou, Liucheng Zhou and Xiangfan Nie
Materials 2022, 15(18), 6501; https://doi.org/10.3390/ma15186501 - 19 Sep 2022
Cited by 3 | Viewed by 1465
Abstract
Laser shock peening (LSP) has been employed to improve the mechanical properties of repaired aerospace engine components via laser metal deposition (LMD). This study looked at cross-sectional residual stress, microstructure and high cyclic fatigue performance. The outcomes demonstrated that a compressive residual stress [...] Read more.
Laser shock peening (LSP) has been employed to improve the mechanical properties of repaired aerospace engine components via laser metal deposition (LMD). This study looked at cross-sectional residual stress, microstructure and high cyclic fatigue performance. The outcomes demonstrated that a compressive residual stress layer with a value of 240 MPa was formed at a depth of 200 μm in the laser melting deposited zone and the microhardness was improved by 13.1%. The findings of electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analysis revealed that misorientation increased and dislocation features were observed after LSP which is beneficial to the enhancement of fatigue performance. The high cycle fatigue data illustrated that the LMD+LSPned samples exhibited 61% improvement in comparison to the as-LMD samples. In the aerospace sector, LSP and LMD are therefore very effective and promising techniques for restoring high-value components. Full article
(This article belongs to the Topic Surface Engineered Materials)
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16 pages, 6763 KiB  
Article
Synthesis and Properties of the Gallium-Containing Ruddlesden-Popper Oxides with High-Entropy B-Site Arrangement
by Juliusz Dąbrowa, Jan Adamczyk, Anna Stępień, Marek Zajusz, Karolina Bar, Katarzyna Berent and Konrad Świerczek
Materials 2022, 15(18), 6500; https://doi.org/10.3390/ma15186500 - 19 Sep 2022
Cited by 4 | Viewed by 1750
Abstract
For the first time, the possibility of obtaining B-site disordered, Ruddlesden–Popper type, high-entropy oxides has been proven, using as an example the LnSr(Co,Fe,Ga,Mn,Ni)O4 series (Ln = La, Pr, Nd, Sm, or Gd). The materials were synthesized using the Pechini method, followed by [...] Read more.
For the first time, the possibility of obtaining B-site disordered, Ruddlesden–Popper type, high-entropy oxides has been proven, using as an example the LnSr(Co,Fe,Ga,Mn,Ni)O4 series (Ln = La, Pr, Nd, Sm, or Gd). The materials were synthesized using the Pechini method, followed by sintering at a temperature of 1200 °C. The XRD analysis indicated the single-phase, I4/mmm structure of the Pr-, Nd-, and Sm-based materials, with a minor content of secondary phase precipitates in La- and Gd-based materials. The SEM + EDX analysis confirms the homogeneity of the studied samples. Based on the oxygen non-stoichiometry measurements, the general formula of LnSr(Co,Fe,Ga,Mn,Ni)O4+δ, is established, with the content of oxygen interstitials being surprisingly similar across the series. The temperature dependence of the total conductivity is similar for all materials, with the highest conductivity value of 4.28 S/cm being reported for the Sm-based composition. The thermal expansion coefficient is, again, almost identical across the series, with the values varying between 14.6 and 15.2 × 10−6 K−1. The temperature stability of the selected materials is verified using the in situ high-temperature XRD. The results indicate a smaller impact of the lanthanide cation type on the properties than has typically been reported for conventional Ruddlesden–Popper type oxides, which may result from the high-entropy arrangement of the B-site cations. Full article
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18 pages, 6947 KiB  
Article
Effect of the Synthesis Conditions of MIL-100(Fe) on Its Catalytic Properties and Stability under Reaction Conditions
by José J. Delgado-Marín, Javier Narciso and Enrique V. Ramos-Fernández
Materials 2022, 15(18), 6499; https://doi.org/10.3390/ma15186499 - 19 Sep 2022
Cited by 3 | Viewed by 2414
Abstract
MIL-100(Fe) is a metal–organic framework (MOF) characterized by the presence of Lewis acid and Fe(II/III) redox sites. In this work, different synthesis methods for the preparation of MIL-100(Fe) are studied. Depending on the source of fluorine, different phases can be obtained: MIL-100(Fe) and [...] Read more.
MIL-100(Fe) is a metal–organic framework (MOF) characterized by the presence of Lewis acid and Fe(II/III) redox sites. In this work, different synthesis methods for the preparation of MIL-100(Fe) are studied. Depending on the source of fluorine, different phases can be obtained: MIL-100(Fe) and an Fe trimesate with unknown structure which we call Fe(BTC). These materials were characterized using numerous techniques and applied in the reaction of CO2 cycloaddition with epichlorohydrin, a reaction catalyzed by Lewis acid sites. It was observed that samples with more Fe(BTC) phase were more active in the reaction. However, all samples, under reaction conditions, transformed into a less active phase. Full article
(This article belongs to the Special Issue Design and Applications of Functional Materials)
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15 pages, 5778 KiB  
Article
Analysis of the Influence of GMAW Process Parameters on the Properties and Microstructure of S32001 Steel
by Sandra Chacón-Fernández, Antonio Portolés García and Gerardo Romaní Labanda
Materials 2022, 15(18), 6498; https://doi.org/10.3390/ma15186498 - 19 Sep 2022
Cited by 7 | Viewed by 1404
Abstract
The properties of duplex steels can be seriously affected when welding processes are performed on them. Duplex S32001 is a recent development, so there is very little published information on its behavior after a welding process. For this reason, the present article determines [...] Read more.
The properties of duplex steels can be seriously affected when welding processes are performed on them. Duplex S32001 is a recent development, so there is very little published information on its behavior after a welding process. For this reason, the present article determines how the main welding parameters of the GMAW process influence its mechanical and microstructural properties. From this study, it was determined that the parameter W/m3 best defines the phase balance in the bead due to the values involved. In the HAZ, this parameter is the t12/8. The welding parameters that are used determine the bead dimensions and geometry. These dimensions induce differences in the distribution of heat in the material. For this reason, the thermal cycles undergone by the material vary and, consequently, in the phase balance obtained. A theoretical study of the chemical composition in the bead, through dilution, and in the HAZ, through diffusion, was carried out. A mathematical model was developed that allows the variation of the composition in the HAZ that induces diffusion to be determined. Full article
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14 pages, 4056 KiB  
Article
Gel Point Determination in Resin Transfer Molding Process with Fiber Bragg Grating Inscribed in Side-Hole Elliptical Core Optical Fiber
by Karol Wachtarczyk, Marcel Bender, Ewald Fauster, Ralf Schledjewski, Paweł Gąsior and Jerzy Kaleta
Materials 2022, 15(18), 6497; https://doi.org/10.3390/ma15186497 - 19 Sep 2022
Cited by 1 | Viewed by 1665
Abstract
Material as well as process variations in the composites industry are reasons to develop methods for in-line monitoring, which would increase reproducibility of the manufacturing process and the final composite products. Fiber Bragg Gratings (FBGs) have shown to be useful for monitoring liquid-composite [...] Read more.
Material as well as process variations in the composites industry are reasons to develop methods for in-line monitoring, which would increase reproducibility of the manufacturing process and the final composite products. Fiber Bragg Gratings (FBGs) have shown to be useful for monitoring liquid-composite molding processes, e.g., in terms of online gel point detection. Existing works however, focus on in-plane strain measurements while out-of-plane residual strain prevails. In order to measure out-of-plane strain, FBG inscribed in highly birefringent fiber (HB FBG) can be used. The purpose of this research is the cure stage detection with (a) FBG inscribed in single mode and (b) FBG inscribed in highly-birefringent side-hole fiber in comparison to the reference gel point detected with an in-mold DC sensor. Results reveal that the curing process is better traceable with HB FBG than with regular FBG. Thus, the use of HB FBG can be a good method for the gel point estimation in the RTM process. Full article
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20 pages, 4897 KiB  
Article
Dynamic Response and Service Life of Tunnel Bottom Structure Considering Hydro-Mechanical Coupling Effect under the Condition of Bedrock Softening
by Dengke Wang, Jianjun Luo, Feilong Li, Guanqing Wang, Lei Wang, Jie Su, Zhen Gao and Kunyao Yin
Materials 2022, 15(18), 6496; https://doi.org/10.3390/ma15186496 - 19 Sep 2022
Cited by 2 | Viewed by 1369
Abstract
Due to the long-term coupling effect of a train load and groundwater, the surrounding rock at the tunnel bottom will soften in a certain range and the mechanical parameters of the surrounding rock will decrease, causing the uneven distribution of the confining pressure [...] Read more.
Due to the long-term coupling effect of a train load and groundwater, the surrounding rock at the tunnel bottom will soften in a certain range and the mechanical parameters of the surrounding rock will decrease, causing the uneven distribution of the confining pressure at the tunnel bottom and affecting the base concrete structure service life. In this research, the method of combining field tests and numerical simulation is adopted, and the vertical displacement, vertical acceleration, and maximum and minimum principal stresses are used as evaluation indicators. The dynamic response law of the base structure with the softened surrounding rock of the heavy-duty train is analyzed, and the Miner linear cumulative damage theory is introduced to obtain the service life of the tunnel bottom structure under different softening conditions. The results show that with the decrease in the softening coefficient and the increase in the softening thickness of the bedrock, the displacement, acceleration, and principal stress response indexes of the structure increase by varying degrees, and the service life of the base structure decreases almost linearly. The maximum vertical displacement, acceleration, and tensile stress are located directly below the track, and the maximum compressive stress is located at the connection between the inverted arch and the side wall. According to the predicted value of the service life, the reliability of the base structure is divided into four levels: safety, warning, danger, and serious danger. Full article
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21 pages, 4975 KiB  
Article
Interaction of Geopolymer Filler and Alkali Molarity Concentration towards the Fire Properties of Glass-Reinforced Epoxy Composites Fabricated Using Filament Winding Technique
by Mohammad Firdaus Abu Hashim, Meor Ahmad Faris, Md Azree Othuman Mydin, Che Mohd Ruzaidi Ghazali, Yusrina Mat Daud, Mohd Mustafa Al Bakri Abdullah, Farah Farhana Zainal, Saloma, Muhammad Faheem Mohd Tahir, Heah Cheng Yong and Morteza Khorami
Materials 2022, 15(18), 6495; https://doi.org/10.3390/ma15186495 - 19 Sep 2022
Cited by 3 | Viewed by 1742
Abstract
This paper aims to find out the effect of different weight percentages of geopolymer filler in glass-reinforced epoxy pipe, and which can achieve the best mechanical properties and adhesion between high calcium pozzolanic-based geopolymer matrices. Different weight percentages and molarities of epoxy hardener [...] Read more.
This paper aims to find out the effect of different weight percentages of geopolymer filler in glass-reinforced epoxy pipe, and which can achieve the best mechanical properties and adhesion between high calcium pozzolanic-based geopolymer matrices. Different weight percentages and molarities of epoxy hardener resin and high calcium pozzolanic-based geopolymer were injected into the glass fiber. By manually winding filaments, composite samples were produced, and they were then allowed to cure at room temperature. To determine how well the geopolymer matrices adhere to the fiber reinforcement, the microstructure of the composites’ surfaces and perpendicular sections were examined. Maximum values of compressive strength and compressive modulus were 94.64 MPa and 2373.58 MPa, respectively, for the sample with a weight percentage of filler loading of 30 wt% for an alkali concentration of 12 M. This is a relatively wide range of geopolymer weight percentage of filler loading from 10 wt% to 40 wt%, at which we can obtain high compressive properties. By referring to microstructural analysis, adhesion, and interaction of the geopolymer matrix to glass fiber, it shows that the filler is well-dispersed and embedded at the fiber glass, and it was difficult to determine the differences within the range of optimal geopolymer filler content. By determining the optimum weight percent of 30 wt% of geopolymer filler and microstructural analysis, the maximum parameter has been achieved via analysis of high calcium pozzolanic-based geopolymer filler. Fire or elevated temperature represents one of the extreme ambient conditions that any structure may be exposed to during its service life. The heat resistance or thermal analysis between glass-reinforced epoxy (GRE) pipe and glass-reinforced epoxy pipe filled with high calcium pozzolanic-based geopolymer filler was studied by investigating burning tests on the samples, which shows that the addition of high calcium pozzolanic-based geopolymer filler results in a significant reduction of the melted epoxy. Full article
(This article belongs to the Section Polymeric Materials)
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5 pages, 190 KiB  
Editorial
Multiscale Simulation of Composite Structures: Damage Assessment, Mechanical Analysis and Prediction
by Stelios K. Georgantzinos
Materials 2022, 15(18), 6494; https://doi.org/10.3390/ma15186494 - 19 Sep 2022
Cited by 3 | Viewed by 1278
Abstract
Composites can be engineered to exhibit high strength, high stiffness, and high toughness. Composite structures have been used increasingly in various engineering applications. In recent decades, most fundamentals of science have expanded their reach by many orders of magnitude. Currently, one of the [...] Read more.
Composites can be engineered to exhibit high strength, high stiffness, and high toughness. Composite structures have been used increasingly in various engineering applications. In recent decades, most fundamentals of science have expanded their reach by many orders of magnitude. Currently, one of the primary goals of science and technology seems to be the quest to develop reliable methods for linking the physical phenomena that occur over multiple length scales, particularly from a nano-/micro-scale to a macroscale. The aim of this Special Issue is to assemble high quality papers that advance the field of multiscale simulation of composite structures, through the application of any modern computational and/or analytical methods alone or in conjunction with experimental techniques, for damage assessment or mechanical analysis and prediction. Full article
18 pages, 2347 KiB  
Article
Advanced Biofuels from ABE (Acetone/Butanol/Ethanol) and Vegetable Oils (Castor or Sunflower Oil) for Using in Triple Blends with Diesel: Evaluation on a Diesel Engine
by Laura Aguado-Deblas, Francisco J. López-Tenllado, Diego Luna, Felipa M. Bautista, Antonio A. Romero and Rafael Estevez
Materials 2022, 15(18), 6493; https://doi.org/10.3390/ma15186493 - 19 Sep 2022
Cited by 8 | Viewed by 1711
Abstract
From a technical and economic point of view, our aim is to provide viable solutions for the replacement of fossil fuels which are currently used in internal combustion diesel engines. In this research, two new biofuels composed of second-generation vegetable oils (SVO),used oil [...] Read more.
From a technical and economic point of view, our aim is to provide viable solutions for the replacement of fossil fuels which are currently used in internal combustion diesel engines. In this research, two new biofuels composed of second-generation vegetable oils (SVO),used oil sunflower (SO) or castor oil (CO), and the ABE blend (acetone/butanol/ethanol) were evaluated. ABE is an intermediate product from the fermentation of carbohydrates to obtain bio-butanol. Besides, the ABE blend exhibits suitable properties as biofuel, such asvery low kinematic viscosity, reasonable energy density, low autoignition temperature, and broad flammability limits. Diesel/ABE/SVO triple blends were prepared, characterized and then, tested on a diesel engine, evaluating power output, consumption, and exhaust emissions. The power output was slightly reduced due to the low heating values of ABE blend. Also, engine consumed more fuel with the triple blends than with diesel under low engine loads whereas, at medium and high loads, the fuel consumption was very similar to that of diesel. Regarding exhaust gas emissions, soot wasnotably reduced, and nitrogen oxides (NOx) and carbon monoxide (CO2) emissions were lower or comparable to that of diesel, while the CO emissions increased. The use of these biofuels allows the replacement of high percentagesof diesel without compromising engine power and achievinga significant reduction in pollution emissions. Furthermore, a notable improvement in cold flow properties of the fuel blends is obtained, in comparison with diesel. Full article
(This article belongs to the Special Issue Recent Advances and Applications of Biofuel)
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14 pages, 3354 KiB  
Article
Influence of the Accelerated Aging Process on the Fragment-Resistant Properties of Para-Aramid Body Armor
by Katarzyna Kośla, Marcin Łandwijt, Michał Miklas and Marzena Fejdyś
Materials 2022, 15(18), 6492; https://doi.org/10.3390/ma15186492 - 19 Sep 2022
Cited by 2 | Viewed by 1442
Abstract
Para-aramid materials such as Twaron® and Kevlar® are commonly used for ballistic-resistant body armor, which are designed to protect human life and health. For this reason, the materials from which body armor are made should be thoroughly investigated in the area [...] Read more.
Para-aramid materials such as Twaron® and Kevlar® are commonly used for ballistic-resistant body armor, which are designed to protect human life and health. For this reason, the materials from which body armor are made should be thoroughly investigated in the area of long-term reliability, particularly with regard to exposure to UV light, humidity and temperature, as these are known causes of degradation in commonly used ballistic materials. This research presents the durability of soft and hard ballistic inserts designed using para-aramid (Twaron®) materials. Para-aramid ballistic inserts not subjected to accelerated aging processes and also ones subjected to laboratory aging for 63, 129 and 194 days, which corresponded to 2, 4 and 6 years of aging in real conditions, were tested. The selected para-aramid inserts were verified in terms of ballistic and physico-mechanical properties as well as changes in chemical structure of the ballistic materials. Ballistic tests were carried out with the use of a 1.1 g FSP.22 fragment according to STANAG 2920. Changes in the microstructure of the para-aramid materials were evaluated using infrared spectroscopy and scanning electron microscopy. The obtained results indicate that despite the changes which took place at the molecular level in the Twaron® materials, accelerated aging processes do not affect the fragmentation resistance properties of ballistic inserts made of para-aramid materials. Full article
(This article belongs to the Special Issue Materials Dedicated for Armours and Protection Systems)
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15 pages, 2950 KiB  
Article
Reprocessed Materials Used in Rotationally Moulded Sandwich Structures for Enhancing Environmental Sustainability: Low-Velocity Impact and Flexure-after-Impact Responses
by Abu Saifullah, Pappu Radhakrishnan, Lei Wang, Burhan Saeed, Forkan Sarker and Hom N. Dhakal
Materials 2022, 15(18), 6491; https://doi.org/10.3390/ma15186491 - 19 Sep 2022
Cited by 4 | Viewed by 1423
Abstract
In the rotational moulding industry, non-used, scrap, and waste purge materials have tremendous potential to be reprocessed and applied in skin-foam-skin sandwich structures to replace and reduce the use of virgin polymers. This approach not only encourages the re-use of these waste materials [...] Read more.
In the rotational moulding industry, non-used, scrap, and waste purge materials have tremendous potential to be reprocessed and applied in skin-foam-skin sandwich structures to replace and reduce the use of virgin polymers. This approach not only encourages the re-use of these waste materials but also significantly contributes to reduce environmental impacts associated with the use of virgin polymers in this sector. The demand of rotationally moulded sandwich structures is rapidly increasing in automotive, marine, and storage tanks, where investigating their impact and after-impact responses are crucial. Hence, this study investigated the low-velocity impact (LVI) and flexure-after-impact (FAI) responses of rotationally moulded sandwich structures manufactured using reprocessed materials. Results obtained from LVI induced damage at two different incident energy levels (15 J, 30 J), and the residual flexural strength of impacted structures evaluated by three-points bending tests were compared with non-reprocessed sandwich structures (virgin materials). The impact damage progression mechanism was characterized using the X-ray micro-computer-tomography technique. Reprocessed sandwiches demonstrated 91% and 66% post-impact residual strength at 15 J and 30 J respectively, while for non-reprocessed sandwiches, these values were calculated as 93% and 88%. Although reprocessed sandwich structures showed a lower performance over non-reprocessed sandwiches, they have a strong potential to be used in sandwich structures for various applications. Full article
(This article belongs to the Special Issue Sandwich Composites: Design, Simulation and Applications)
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17 pages, 4845 KiB  
Article
A Mesoscale Study on the Dilation of Actively Confined Concrete under Axial Compression
by Peng Chen, Xiaomeng Cui, Huijun Zheng and Shengpu Si
Materials 2022, 15(18), 6490; https://doi.org/10.3390/ma15186490 - 19 Sep 2022
Cited by 3 | Viewed by 1413
Abstract
The confinement of concrete enhances its strength and ductility by restraining lateral dilation. The accuracy of a confinement model depends on how well it captures the dilation of concrete. In the current paper, a mesoscale model is established to study the dilation properties [...] Read more.
The confinement of concrete enhances its strength and ductility by restraining lateral dilation. The accuracy of a confinement model depends on how well it captures the dilation of concrete. In the current paper, a mesoscale model is established to study the dilation properties of concrete in active confinement, where the heterogeneity of concrete is considered. The stress–strain and lateral–axial strain curves of concrete in active confinement were used to demonstrate the validity of the mesoscale model. Subsequently, the distribution of lateral strain and the influences of the strength grade and confinement ratio on the dilation of concrete were investigated in a simulation. The results show that the distribution of the lateral strain along the radial or longitudinal directions is not uniform on the specimen when compressive failure occurs. The confinement ratio has a more significant influence on the concrete’s transverse dilation than the strength grade. Finally, an expression of the lateral–axial strain relationship of concrete in active confinement is proposed. The proposed formula can reflect the simulation results of the mesoscale model and is in good agreement with the prediction of existing formulas. Full article
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22 pages, 4651 KiB  
Article
Liquid Moisture Transport in Cotton Woven Fabrics with Different Weft Yarns
by Małgorzata Matusiak and Dominika Kamińska
Materials 2022, 15(18), 6489; https://doi.org/10.3390/ma15186489 - 19 Sep 2022
Cited by 4 | Viewed by 1787
Abstract
Moisture transport in fabrics influences the thermal comfort of clothing due to drainage of sweat secreted by the human body. The moisture transport through textile materials takes place in two ways: water-vapor transport and liquid moisture transport. Both ways are equally important. In [...] Read more.
Moisture transport in fabrics influences the thermal comfort of clothing due to drainage of sweat secreted by the human body. The moisture transport through textile materials takes place in two ways: water-vapor transport and liquid moisture transport. Both ways are equally important. In the present work, liquid moisture transport in cotton woven fabrics with different weft yarns was investigated. Measurement was done using the Moisture Management Tester MMT M290. The obtained results confirmed that the linear density of weft yarn significantly influenced the values of all parameters characterizing liquid moisture transport in the investigated fabrics. The best performance in liquid moisture transport was achieved by weft yarn of linear density 30 tex. For this fabric variant, the maximum wetted radius for both surfaces was the biggest: 25 mm for the inner and 26.6 mm for the outer surface of the fabric. This means that the fabric spread the liquid on the biggest area compared to the other variants being investigated to facilitate an evaporation of liquid sweat. The fabric variant with 30 tex weft yarn showed the highest spreading speed: 5.83 mm/s for both sides, and the shortest wetting time: 2.83 s for the inner and 3.00 s for the outer side of the fabric. The higher the linear density of weft yarn, the worse the ability of cotton woven fabrics to ensure liquid moisture transport. Full article
(This article belongs to the Special Issue Mechanical Behaviors of Materials: Modelling and Measurement)
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11 pages, 4527 KiB  
Article
Fabrication of Copper Matrix Composites Reinforced with Carbon Nanotubes Using an Innovational Self-Reduction Molecular-Level-Mixing Method
by Bin Ya, Yang Xu, Linggang Meng, Bingwen Zhou, Junfei Zhao, Xi Chen and Xingguo Zhang
Materials 2022, 15(18), 6488; https://doi.org/10.3390/ma15186488 - 19 Sep 2022
Cited by 4 | Viewed by 1678
Abstract
An innovational self-reduction molecular-level-mixing method was proposed as a simplified manufacturing technique for the production of carbon nanotube copper matrix composites (CNT/Cu). Copper matrix composites reinforced with varying amounts of (0.1, 0.3, 0.5 and 0.7 wt%) carbon nanotubes were fabricated by using this [...] Read more.
An innovational self-reduction molecular-level-mixing method was proposed as a simplified manufacturing technique for the production of carbon nanotube copper matrix composites (CNT/Cu). Copper matrix composites reinforced with varying amounts of (0.1, 0.3, 0.5 and 0.7 wt%) carbon nanotubes were fabricated by using this method combined with hot-pressing sintering technology. The surface structure and elemental distribution during the preparation of CNT/Cu mixing powder were investigated. The microstructure and comprehensive properties of the CNT/Cu composites were examined by metallography, mechanical and electrical conductivity tests. The results revealed that the CNT/Cu could be produced by a high temperature reaction at 900 degrees under vacuum, during which the carbon atoms in the carbon nanotubes reduced the divalent copper on the surface to zero-valent copper monomers. The decrease in the ratio of D and G peaks on the Raman spectra indicated that the defective spots on the carbon nanotubes were wrapped and covered by the copper atoms after a self-reduction reaction. The prepared CNT/Cu powders were uniformly embedded in the grain boundaries of the copper matrix materials and effectively hindered the tensile fracture. The overall characteristics of the CNT/Cu composites steadily increased with increasing CNT until the maximum at 0.7 wt%. The performance was achieved with a hardness of 86.1 HV, an electrical conductivity of 81.8% IACS, and tensile strength of 227.5 MPa. Full article
(This article belongs to the Special Issue Alloys and Composites: Structural and Functional Applications)
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9 pages, 1776 KiB  
Article
Enhanced Design of Gold Catalysts for Bioorthogonal Polyzymes
by Cristina-Maria Hirschbiegel, Stefano Fedeli, Xianzhi Zhang, Rui Huang, Jungmi Park, Yisheng Xu and Vincent M. Rotello
Materials 2022, 15(18), 6487; https://doi.org/10.3390/ma15186487 - 19 Sep 2022
Cited by 7 | Viewed by 2127
Abstract
Bioorthogonal chemistry introduces nonbiogenic reactions that can be performed in biological systems, allowing for the localized release of therapeutic agents. Bioorthogonal catalysts can amplify uncaging reactions for the in situ generation of therapeutics. Embedding these catalysts into a polymeric nanoscaffold can protect and [...] Read more.
Bioorthogonal chemistry introduces nonbiogenic reactions that can be performed in biological systems, allowing for the localized release of therapeutic agents. Bioorthogonal catalysts can amplify uncaging reactions for the in situ generation of therapeutics. Embedding these catalysts into a polymeric nanoscaffold can protect and modulate the catalytic activity, improving the performance of the resulting bioorthogonal “polyzymes”. Catalysts based on nontoxic metals such as gold(I) are particularly attractive for therapeutic applications. Herein, we optimized the structural components of a metal catalyst to develop an efficient gold(I)-based polyzyme. Tailoring the ligand structure of gold phosphine-based complexes, we improved the affinity between the metal complex and polymer scaffold, resulting in enhanced encapsulation efficiency and catalytic rate of the polyzyme. Our findings show the dependence of the overall polyzyme properties on the structural properties of the encapsulated metal complex. Full article
(This article belongs to the Special Issue Delivery Nanomaterials for Cancer Therapy)
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17 pages, 7484 KiB  
Article
Development of Test Methods to Evaluate the Printability of Concrete Materials for Additive Manufacturing
by Youssef Mortada, Malek Mohammad, Bilal Mansoor, Zachary Grasley and Eyad Masad
Materials 2022, 15(18), 6486; https://doi.org/10.3390/ma15186486 - 19 Sep 2022
Cited by 3 | Viewed by 1788
Abstract
This study proposes test methods for assessing the printability of concrete materials for Additive Manufacturing. The printability of concrete is divided into three main aspects: flowability, setting time, and buildability. These properties are considered to monitor the critical quality of 3DCP and to [...] Read more.
This study proposes test methods for assessing the printability of concrete materials for Additive Manufacturing. The printability of concrete is divided into three main aspects: flowability, setting time, and buildability. These properties are considered to monitor the critical quality of 3DCP and to ensure a successful print. Flowability is evaluated through a rheometer test, where the evolution of shear yield strength is monitored at a constant rate (rpm), similar to the printer setup. Flowability limits were set based on the user-defined maximum thickness of a printed layer and the onset of gaps/cracks during printing. Setting time is evaluated through an ultrasonic wave pulse velocity test (UPV), where the first inflection point of the evolution of the UPV graph corresponds to the setting time of the concrete specimen. The results from this continuous non-destructive test were found to correlate with the results from the discrete destructive ASTM C-191 test for measuring setting time with a maximum difference of 5% between both sets of values. Lastly, buildability was evaluated through the measurement of the early-age compressive strength of concrete, and a correlation with the UPV results obtained a predictive model that can be used in real-time to non-destructively assess the material buildability. This predictive model had a maximum percentage difference of 13% with the measured values. The outcome of this study is a set of tests to evaluate the properties of 3D printable concrete (3DP) material and provide a basis for a framework to benchmark and design materials for additive manufacturing. Full article
(This article belongs to the Special Issue 3D Printing Techniques in Construction Materials)
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16 pages, 3358 KiB  
Article
Effect of Flocculants Residue on Rheological Properties of Ultra-Fine Argillaceous Backfilling Slurry
by Shuai Li, Zheng Yu, Boyi Hu, Haoxuan Yu and Xinmin Wang
Materials 2022, 15(18), 6485; https://doi.org/10.3390/ma15186485 - 19 Sep 2022
Cited by 2 | Viewed by 1457
Abstract
Tailings concentration is indispensable for backfilling. Additionally, the residual flocculants in the concentration process affect the rheological properties of ultra-fine argillaceous backfilling slurry (e.g., viscosity and yield stress), resulting in a great effect on the fluidity and resistance of pipeline transportation. In this [...] Read more.
Tailings concentration is indispensable for backfilling. Additionally, the residual flocculants in the concentration process affect the rheological properties of ultra-fine argillaceous backfilling slurry (e.g., viscosity and yield stress), resulting in a great effect on the fluidity and resistance of pipeline transportation. In this study, to explore the effect of flocculants residue on the rheological properties of the slurry, a series of rheological tests (constant shear rate test and variable shear rate test) were performed by changing the type, dosage, stirring time, temperature of flocculants addition and the amount of binder added. The results showed that the addition of flocculants increased the viscosity and yield stress of slurry. At a certain amount of flocculants additive, the flocculant network structure reached the best development state, which had a positive effect on increasing slurry viscosity and yield stress. As the stirring time increased, the scale of damage to the flocculant network structure became larger, which had a negative effect on increasing slurry viscosity and yield stress. Low temperature weakened the adsorption and bridging effect of polymeric chains, resulting in a poorly developed flocculant network structure, which had a negative effect on increasing slurry viscosity and yield stress. Caused by hydration products, the viscosity and yield stress of slurry with binder further increased. This study is significant for an in-depth study of the rheological and pipeline transport characteristics of ultra-fine argillaceous backfilling slurry, optimising the selection of flocculants for ultrafine particles, guiding backfill parameters and improving the reliability of pipeline transport. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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18 pages, 5789 KiB  
Article
Influence of 40% Cold Working and Annealing on Precipitation in AISI 316L Austenitic Stainless Steel
by Katarína Bártová, Mária Dománková, Jozef Bárta and Peter Pastier
Materials 2022, 15(18), 6484; https://doi.org/10.3390/ma15186484 - 19 Sep 2022
Cited by 1 | Viewed by 1679
Abstract
Intergranular corrosion is one of the most important processes affecting the behaviour of austenitic stainless steels. Factors such as steel chemical composition, the degree of prior deformation and the exposure temperature affect the degree of sensitisation. AISI 316L (0% CW) steel was annealed [...] Read more.
Intergranular corrosion is one of the most important processes affecting the behaviour of austenitic stainless steels. Factors such as steel chemical composition, the degree of prior deformation and the exposure temperature affect the degree of sensitisation. AISI 316L (0% CW) steel was annealed at 650 °C for 5, 10, 30, 100, 300 and 1000 h to analyse the influence of isothermal annealing on the precipitation of secondary phases. AISI 316L steel after 40% cold working and subsequent annealing at 650 °C for 1, 1.5, 2, 5 and 10 h was investigated. Time–temperature sensitisation (TTS) diagrams were created based on corrosion test (ASTM A 262, practice A) results. In the case of AISI 316L (0% CW), M23C6, chi and sigma phases precipitated at grain boundaries, and the Laves phase was mainly inside of the grains. In the case of AISI 316L (40% CW), sigma, chi, Laves and M23C6 were identified and precipitated mainly along the grain boundaries as well as on the shear bands within different annealing times. It was confirmed that the increase in the annealing time caused an increase in the amounts of secondary phases. Secondary phases in the equilibrium state were calculated using Thermo-Calc software. Full article
(This article belongs to the Topic Corrosion and Protection of Metallic Materials)
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11 pages, 1624 KiB  
Article
Microstructure and Magnetic Properties of Nanocrystalline Fe60−xCo25Ni15Six Alloy Elaborated by High-Energy Mechanical Milling
by Nawel Khitouni, Béchir Hammami, Núria Llorca-Isern, Wael Ben Mbarek, Joan-Josep Suñol and Mohamed Khitouni
Materials 2022, 15(18), 6483; https://doi.org/10.3390/ma15186483 - 19 Sep 2022
Cited by 3 | Viewed by 1628
Abstract
In the present work, the effect of Si addition on the magnetic properties of Fe60−xCo25Ni15Six (x = 0, 5, 10, 20, and 30 at%) alloys prepared by mechanical alloying was analyzed by X-ray diffraction and magnetic [...] Read more.
In the present work, the effect of Si addition on the magnetic properties of Fe60−xCo25Ni15Six (x = 0, 5, 10, 20, and 30 at%) alloys prepared by mechanical alloying was analyzed by X-ray diffraction and magnetic vibrating sample magnetometry and SQUID. The crystallographic parameters of the bcc-solid solutions were calculated by Rietveld refinement of the X-ray diffraction patterns with Maud software. Scanning electron microscopy (SEM) was used to determine the morphology of the powdered alloys as a function of milling time. It was found that the Si addition has an important role in the increase of structural hardening and brittleness of the particles (favoring the more pronounced refinement of crystallites). The resulting nanostructure is highlighted in accordance with the concept of the structure of defects. Magnetic properties were related to the metalloid addition, formed phases, and chemical compositions. All processed samples showed a soft ferromagnetic behavior (Hc ≤ 100 Oe). The inhomogeneous evolution of the magnetization saturation as a function of milling time is explained by the magnetostriction effective anisotropy and stress induced during mechanical alloying. Full article
(This article belongs to the Special Issue Novel Materials Synthesis by Mechanical Alloying/Milling (Volume II))
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11 pages, 526 KiB  
Article
Alkalizing Properties of Six Calcium-Silicate Endodontic Biomaterials
by Katarzyna Kot, Łukasz Kucharski, Ewa Marek, Krzysztof Safranow and Mariusz Lipski
Materials 2022, 15(18), 6482; https://doi.org/10.3390/ma15186482 - 19 Sep 2022
Cited by 8 | Viewed by 1584
Abstract
Introduction: Calcium silicate-based cements (CSC), are self-setting hydraulic biomaterials widely used for reparative procedures in dentistry and endodontics. These materials possess physical properties, such as ion release, porosity, solubility, and radiopacity. Their biological properties are connected to their alkalizing activity and calcium release [...] Read more.
Introduction: Calcium silicate-based cements (CSC), are self-setting hydraulic biomaterials widely used for reparative procedures in dentistry and endodontics. These materials possess physical properties, such as ion release, porosity, solubility, and radiopacity. Their biological properties are connected to their alkalizing activity and calcium release capacity. Materials and Methods: Six calcium silicate-based materials were selected for this study: TheraCal LC (Bisco Inc., Schaumburg, IL, USA), MTA Plus (PrevestDenpro, Jammu, India Avalon Biomed Inc., Bradenton, FL, USA), Biodentine (Septodont, Saint-Maur-des-Fossés, France), RetroMTA (BioMTA, Seoul, Korea), MTA Flow (Ultradent Products, Inc., South Jordan, UT, USA), and OrthoMTA (BioMTA, Seoul, Korea). The pH was analyzed immediately after immersion (baseline) and after 1 h, 3 h, 1 day, 2 days, 3 days, 1 week, 2 weeks, 3 weeks, and 1 year with a pH meter, previously calibrated with solutions of known pH. All testing materials had alkaline pH. Results: Analysis of the tested materials showed statistically significant differences in terms of pH changes as a function of the time showed a gradual rise in the pH of all materials. Conclusions: All tested materials exhibited continuous hydroxyl ion release resulting in a rise in pH until the end of time of experience. Full article
(This article belongs to the Special Issue Advanced Biomaterials in Dentistry and Healthcare)
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10 pages, 2439 KiB  
Article
Biocompatibility of Zinc Matrix Biodegradable Composites Reinforced by Graphene Nanosheets
by Mei Fan, Fei Zhao, Shanshan Peng, Qianfei Dai, Yuan Liu, Sheng Yin and Zongkui Zhang
Materials 2022, 15(18), 6481; https://doi.org/10.3390/ma15186481 - 19 Sep 2022
Cited by 6 | Viewed by 1618
Abstract
As a new type of biodegradable implant material, zinc matrix composites have excellent potential in the application of biodegradable implants because of their better corrosion resistance than magnesium matrix materials. Our previous studies have shown that graphene nanosheet reinforced zinc matrix composites (Zn-GNS) [...] Read more.
As a new type of biodegradable implant material, zinc matrix composites have excellent potential in the application of biodegradable implants because of their better corrosion resistance than magnesium matrix materials. Our previous studies have shown that graphene nanosheet reinforced zinc matrix composites (Zn-GNS) prepared by spark plasma sintering (SPS) have good mechanical properties and suitable degradation rate. However, the biocompatibility of zinc matrix composites is still a problem of concern. The cytocompatibility and blood compatibility of pure zinc and Zn-GNS composites in vitro were studied. The results showed that Zn-GNS composites had acceptable toxicity to MG-63 human osteosarcoma cells. In addition, the hemolysis rate of pure zinc and its composites were less than 3%, which has no adverse effect on adhered platelets, and has good antithrombotic and antiadhesion platelets properties. In conclusion, the addition of GNS did not adversely affect the biocompatibility of Zn-GNS composites, which indicated that Zn-GNS composites are a promising candidate for bone implantation. Full article
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16 pages, 8224 KiB  
Article
Rate-Dependent Hysteresis Modeling and Displacement Tracking Control Based on Least-Squares SVM for Axially Pre-Compressed Macro-Fiber Composite Bimorph
by Kaiming Hu, Hujian Ge, Hua Li, Shenglong Xie and Suan Xu
Materials 2022, 15(18), 6480; https://doi.org/10.3390/ma15186480 - 18 Sep 2022
Cited by 5 | Viewed by 1577
Abstract
The new axially pre-compressed macro-fiber composite bimorph (MFC-PBP) can produce large displacement and output power. However, it has the property of strong rate-dependent hysteresis nonlinearity, which challenges the displacement tracking control of morphing structures. In this paper, the least-squares support vector machine (LS-SVM) [...] Read more.
The new axially pre-compressed macro-fiber composite bimorph (MFC-PBP) can produce large displacement and output power. However, it has the property of strong rate-dependent hysteresis nonlinearity, which challenges the displacement tracking control of morphing structures. In this paper, the least-squares support vector machine (LS-SVM) is applied to model the rate-dependent hysteresis of MFC-PBP. Compared with the predicated results of the series model of the Bouc–Wen model and Hammerstein model (BW-H), the LS-SVM model achieved higher predication accuracy and better generalization ability. Based on the LS-SVM hysteresis compensation model, with the support vector pruning, the displacement tracking feedforward compensator is obtained. In order to improve the displacement tracking accuracy, the LS-SVM feedforward compensator combined with the proportional and integral (PI) controller and the feedforward plus feedback control experiment is carried out on the displacement tracking of MFC-PBP. The test results show that the feedforward plus feedback displacement tracking control loop based on the LS-SVM model also has a higher displacement tracking accuracy than that based on the inverse model of BW-H. Full article
(This article belongs to the Special Issue Advances in Smart Materials and Applications)
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17 pages, 7985 KiB  
Article
Research on Vibration Control Technology of Robot Motion Based on Magnetorheological Elastomer
by Xuegong Huang, Yutong Zhai and Guisong He
Materials 2022, 15(18), 6479; https://doi.org/10.3390/ma15186479 - 18 Sep 2022
Cited by 3 | Viewed by 1497
Abstract
The vibration and impact of a humanoid bipedal robot during movements such as walking, running and jumping may cause potential damage to the robot’s mechanical joints and electrical systems. In this paper, a composite bidirectional vibration isolator based on magnetorheological elastomer (MRE) is [...] Read more.
The vibration and impact of a humanoid bipedal robot during movements such as walking, running and jumping may cause potential damage to the robot’s mechanical joints and electrical systems. In this paper, a composite bidirectional vibration isolator based on magnetorheological elastomer (MRE) is designed for the cushioning and damping of a humanoid bipedal robot under foot contact forces. In addition, the vibration isolation performance of the vibration isolator was tested experimentally, and then, a vibration isolator dynamics model was developed. For the bipedal robot foot impact, based on the vibration isolator model, three vibration reduction control algorithms are simulated, and the results show that the vibration damping effect can reach 85%. Finally, the MRE vibration isolator hardware-in-the-loop-simulation experiment platform based on dSPACE has been built to verify the vibration reduction control effect of the fuzzy PID algorithm. The result shows the vibration amplitude attenuates significantly, and this verifies the effectiveness of the fuzzy PID damping control algorithm. Full article
(This article belongs to the Special Issue Advances in Smart Materials and Structures)
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26 pages, 2147 KiB  
Review
The Fabrication and Bonding of Thermoplastic Microfluidics: A Review
by Amid Shakeri, Shadman Khan, Noor Abu Jarad and Tohid F. Didar
Materials 2022, 15(18), 6478; https://doi.org/10.3390/ma15186478 - 18 Sep 2022
Cited by 8 | Viewed by 3482
Abstract
Various fields within biomedical engineering have been afforded rapid scientific advancement through the incorporation of microfluidics. As literature surrounding biological systems become more comprehensive and many microfluidic platforms show potential for commercialization, the development of representative fluidic systems has become more intricate. This [...] Read more.
Various fields within biomedical engineering have been afforded rapid scientific advancement through the incorporation of microfluidics. As literature surrounding biological systems become more comprehensive and many microfluidic platforms show potential for commercialization, the development of representative fluidic systems has become more intricate. This has brought increased scrutiny of the material properties of microfluidic substrates. Thermoplastics have been highlighted as a promising material, given their material adaptability and commercial compatibility. This review provides a comprehensive discussion surrounding recent developments pertaining to thermoplastic microfluidic device fabrication. Existing and emerging approaches related to both microchannel fabrication and device assembly are highlighted, with consideration toward how specific approaches induce physical and/or chemical properties that are optimally suited for relevant real-world applications. Full article
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20 pages, 2697 KiB  
Article
PCA-Based Hybrid Intelligence Models for Estimating the Ultimate Bearing Capacity of Axially Loaded Concrete-Filled Steel Tubes
by Kaffayatullah Khan, Rahul Biswas, Jitendra Gudainiyan, Muhammad Nasir Amin, Hisham Jahangir Qureshi, Abdullah Mohammad Abu Arab and Mudassir Iqbal
Materials 2022, 15(18), 6477; https://doi.org/10.3390/ma15186477 - 18 Sep 2022
Cited by 1 | Viewed by 1616
Abstract
In order to forecast the axial load-carrying capacity of concrete-filled steel tubular (CFST) columns using principal component analysis (PCA), this work compares hybrid models of artificial neural networks (ANNs) and meta-heuristic optimization algorithms (MOAs). In order to create hybrid ANN models, a dataset [...] Read more.
In order to forecast the axial load-carrying capacity of concrete-filled steel tubular (CFST) columns using principal component analysis (PCA), this work compares hybrid models of artificial neural networks (ANNs) and meta-heuristic optimization algorithms (MOAs). In order to create hybrid ANN models, a dataset of 149 experimental tests was initially gathered from the accessible literature. Eight PCA-based hybrid ANNs were created using eight MOAs, including artificial bee colony, ant lion optimization, biogeography-based optimization, differential evolution, genetic algorithm, grey wolf optimizer, moth flame optimization and particle swarm optimization. The created ANNs’ performance was then assessed. With R2 ranges between 0.7094 and 0.9667 in the training phase and between 0.6883 and 0.9634 in the testing phase, we discovered that the accuracy of the built hybrid models was good. Based on the outcomes of the experiments, the generated ANN-GWO (hybrid model of ANN and grey wolf optimizer) produced the most accurate predictions in the training and testing phases, respectively, with R2 = 0.9667 and 0.9634. The created ANN-GWO may be utilised as a substitute tool to estimate the load-carrying capacity of CFST columns in civil engineering projects according to the experimental findings. Full article
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18 pages, 3647 KiB  
Article
Charge-Convertible and Reduction-Sensitive Cholesterol-Containing Amphiphilic Copolymers for Improved Doxorubicin Delivery
by Zhao Wang, Xinyu Guo, Lingyun Hao, Xiaojuan Zhang, Qing Lin and Ruilong Sheng
Materials 2022, 15(18), 6476; https://doi.org/10.3390/ma15186476 - 18 Sep 2022
Cited by 2 | Viewed by 1828
Abstract
For achieving successful chemotherapy against cancer, designing biocompatible drug delivery systems (DDSs) with long circulation times, high cellular endocytosis efficiency, and targeted drug release is of upmost importance. Herein, a well-defined PEG-b-P(MASSChol-co-MANBoc) block copolymer bearing redox-sensitive cholesteryl-side group was [...] Read more.
For achieving successful chemotherapy against cancer, designing biocompatible drug delivery systems (DDSs) with long circulation times, high cellular endocytosis efficiency, and targeted drug release is of upmost importance. Herein, a well-defined PEG-b-P(MASSChol-co-MANBoc) block copolymer bearing redox-sensitive cholesteryl-side group was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization (with non-redox PEG-b-P(MACCChol-co-MAN-DCA) as the reference), and 1,2-dicarboxylic-cyclohexene acid (DCA) was then grafted onto the hydrophobic block to endow it with charge-convertible characteristics under a tumor microenvironment. The amphiphilic copolymer could be assembled into polymeric spherical micelles (SSMCs) with polyethylene glycol (PEG) as the corona/shell, and anti-cancer drug doxorubicin (DOX) was successfully encapsulated into the micellar core via strong hydrophobic and electrostatic interactions. This nanocarrier showed high stability in the physiological environment and demonstrated “smart” surface charge conversion from negative to positive in the slightly acidic environment of tumor tissues (pH 6.5~6.8), as determined by dynamic light scattering (DLS). Moreover, the cleavage of a disulfide bond linking the cholesterol grafts under an intracellular redox environment (10 mM GSH) resulted in micellar dissociation and accelerated drug release, with the non-redox-responsive micelles (CCMCs) as the control. Additionally, a cellular endocytosis and tumor proliferation inhibition study against MCF-7 tumor cells demonstrated the enhanced endocytosis and tumor cell inhibitory efficiency of dual-responsive SSMCs/DOX nanomedicines, revealing potentials as multifunctional nanoplatforms for effective oncology treatment. Full article
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12 pages, 4483 KiB  
Article
Wet Etching of Quartz Using a Solution Based on Organic Solvents and Anhydrous Hydrofluoric Acid
by Yang Wan, Xinghe Luan, Longzao Zhou and Fengshun Wu
Materials 2022, 15(18), 6475; https://doi.org/10.3390/ma15186475 - 18 Sep 2022
Cited by 1 | Viewed by 2149
Abstract
The quartz-crystal resonator is the core device for frequency control in modern communication systems and network technology. At present, in modern resonator blanks manufacturing, BOE solution is usually used as the etching solution, but its etching rate is relatively volatile, and the surface [...] Read more.
The quartz-crystal resonator is the core device for frequency control in modern communication systems and network technology. At present, in modern resonator blanks manufacturing, BOE solution is usually used as the etching solution, but its etching rate is relatively volatile, and the surface morphology of the blanks is prone to defects after etching, which brings certain difficulties to the deep-etching process of the wafer. To solve the above challenges, this paper systematically compares a BOE solution and anhydrous etching solution in terms of etching rate, surface morphology, and electrical properties of the blanks after etching. Seven groups of blanks were etched using different etching solutions with different etching conditions to verify their effect on the surface morphology and electrical properties of quartz blanks. The experimental results suggest that the application of anhydrous etching solution has achieved better surface morphology and electrical properties and can be more suitable for application in batch manufacturing. In general, when using anhydrous etching solution, it is possible to reduce surface roughness by up to 70% and equivalent resistance by 32%, and the etch rate is almost 10 times lower than BOE solution under the same temperature, which is more conducive to the rate control of wafers in the etching process. Full article
(This article belongs to the Special Issue Smart Materials and Structures: Characteristics and Applications)
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16 pages, 3858 KiB  
Article
Selected Properties of Veneered Lightweight Particleboards with Expanded Polystyrene
by Pavlo Bekhta, Ruslan Kozak, Ján Sedliačik, Vladimír Gryc, Václav Sebera, Liubov Bajzová and Ján Iždinský
Materials 2022, 15(18), 6474; https://doi.org/10.3390/ma15186474 - 18 Sep 2022
Cited by 2 | Viewed by 1347
Abstract
The aim of this study was to improve the properties of lightweight particleboards by their veneering. The industrially produced wood particles, rotary-cut birch veneer, expanded polystyrene (EPS) granules and urea-formaldehyde (UF) resin were used to manufacture non-veneered and veneered boards in laboratory conditions. [...] Read more.
The aim of this study was to improve the properties of lightweight particleboards by their veneering. The industrially produced wood particles, rotary-cut birch veneer, expanded polystyrene (EPS) granules and urea-formaldehyde (UF) resin were used to manufacture non-veneered and veneered boards in laboratory conditions. The boards were manufactured with different densities of 350, 450 and 550 kg/m3 and with various levels of EPS content 4, 7 and 10%. Boards without EPS granules as the reference were also manufactured. Bending strength (MOR), modulus of elasticity in bending (MOE), internal bond (IB) strength, thickness swelling (TS) and water absorption (WA) of lightweight particleboards were determined. This study confirmed that veneering of lightweight particleboards by birch veneer improved mechanical properties significantly. The MOR and MOE of veneered boards throughout the whole density range of 350–550 kg/m3 meet the requirements of the CEN/TS 16368 for lightweight particleboards types LP1 and LP2. The IB strength of veneered boards only with density of 550 kg/m3 meets the requirements of CEN/TS 16368 (type LP1). The MOR, MOE and IB of non-veneered boards also meet the requirements of CEN/TS 16368 (type LP1) except boards with density of 350 kg/m3 for MOR and MOE, and except densities of 350 and 450 kg/m3 for IB. Full article
(This article belongs to the Section Advanced Composites)
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