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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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Review

39 pages, 5360 KiB  
Review
The Alphabet of Nanostructured Polypyrrole
by Sylwia Golba and Jan Loskot
Materials 2023, 16(22), 7069; https://doi.org/10.3390/ma16227069 - 7 Nov 2023
Cited by 2 | Viewed by 1880
Abstract
This review is devoted to polypyrrole and its morphology, which governs the electroactivity of the material. The macroscopic properties of the material are strictly relevant to microscopic ordering observed at the local level. During the synthesis, various (nano)morphologies can be produced. The formation [...] Read more.
This review is devoted to polypyrrole and its morphology, which governs the electroactivity of the material. The macroscopic properties of the material are strictly relevant to microscopic ordering observed at the local level. During the synthesis, various (nano)morphologies can be produced. The formation of the ordered structure is dictated by the ability of the local forces and effects to induce restraints that help shape the structure. This review covers the aspects of morphology and roughness and their impact on the final properties of the modified electrode activity in selected applications. Full article
(This article belongs to the Special Issue Conducting Polymers: Structure Characterization, Conductivity, and Application)
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Graphical abstract

20 pages, 8002 KiB  
Review
Recent Progress in Resonant Acoustic Metasurfaces
by Dongan Liu, Limei Hao, Weiren Zhu, Xiao Yang, Xiaole Yan, Chen Guan, You Xie, Shaofang Pang and Zhi Chen
Materials 2023, 16(21), 7044; https://doi.org/10.3390/ma16217044 - 5 Nov 2023
Cited by 7 | Viewed by 3639
Abstract
Acoustic metasurfaces, as two-dimensional acoustic metamaterials, are a current research topic for their sub-wavelength thickness and excellent acoustic wave manipulation. They hold significant promise in noise reduction and isolation, cloaking, camouflage, acoustic imaging, and focusing. Resonant structural units are utilized to construct acoustic [...] Read more.
Acoustic metasurfaces, as two-dimensional acoustic metamaterials, are a current research topic for their sub-wavelength thickness and excellent acoustic wave manipulation. They hold significant promise in noise reduction and isolation, cloaking, camouflage, acoustic imaging, and focusing. Resonant structural units are utilized to construct acoustic metasurfaces with the unique advantage of controlling large wavelengths within a small size. In this paper, the recent research progresses of the resonant metasurfaces are reviewed, covering the design mechanisms and advances of structural units, the classification and application of the resonant metasurfaces, and the tunable metasurfaces. Finally, research interest in this field is predicted in future. Full article
(This article belongs to the Special Issue Metamaterials and Metasurfaces: Fundamentals and Applications)
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17 pages, 2966 KiB  
Review
Molecular Design Concept for Enhancement Charge Carrier Mobility in OFETs: A Review
by Yang Zhou, Keke Zhang, Zhaoyang Chen and Haichang Zhang
Materials 2023, 16(20), 6645; https://doi.org/10.3390/ma16206645 - 11 Oct 2023
Cited by 8 | Viewed by 2712
Abstract
In the last two decades, organic field-effect transistors (OFETs) have garnered increasing attention from the scientific and industrial communities. The performance of OFETs can be evaluated based on three factors: the charge transport mobility (μ), threshold voltage (Vth), and current on/off [...] Read more.
In the last two decades, organic field-effect transistors (OFETs) have garnered increasing attention from the scientific and industrial communities. The performance of OFETs can be evaluated based on three factors: the charge transport mobility (μ), threshold voltage (Vth), and current on/off ratio (Ion/off). To enhance μ, numerous studies have concentrated on optimizing charge transport within the semiconductor layer. These efforts include: (i) extending π-conjugation, enhancing molecular planarity, and optimizing donor–acceptor structures to improve charge transport within individual molecules; and (ii) promoting strong aggregation, achieving well-ordered structures, and reducing molecular distances to enhance charge transport between molecules. In order to obtain a high charge transport mobility, the charge injection from the electrodes into the semiconductor layer is also important. Since a suitable frontier molecular orbitals’ level could align with the work function of the electrodes, in turn forming an Ohmic contact at the interface. OFETs are classified into p-type (hole transport), n-type (electron transport), and ambipolar-type (both hole and electron transport) based on their charge transport characteristics. As of now, the majority of reported conjugated materials are of the p-type semiconductor category, with research on n-type or ambipolar conjugated materials lagging significantly behind. This review introduces the molecular design concept for enhancing charge carrier mobility, addressing both within the semiconductor layer and charge injection aspects. Additionally, the process of designing or converting the semiconductor type is summarized. Lastly, this review discusses potential trends in evolution and challenges and provides an outlook; the ultimate objective is to outline a theoretical framework for designing high-performance organic semiconductors that can advance the development of OFET applications. Full article
(This article belongs to the Special Issue New Advances in π-Conjugated Materials)
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15 pages, 1571 KiB  
Review
Brief Narrative Review on Commercial Dental Sealants—Comparison with Respect to Their Composition and Potential Modifications
by Aleksandra Piszko, Paweł J. Piszko, Adam Lubojański, Wojciech Grzebieluch, Maria Szymonowicz and Maciej Dobrzyński
Materials 2023, 16(19), 6453; https://doi.org/10.3390/ma16196453 - 28 Sep 2023
Cited by 4 | Viewed by 2915
Abstract
The scope of this paper is to compare different dental sealants and flow materials indicated for sealing pits and fissures considering their chemical formula. The narrative review aims to address the following questions: What is the essence of different dental sealants’ activity, how [...] Read more.
The scope of this paper is to compare different dental sealants and flow materials indicated for sealing pits and fissures considering their chemical formula. The narrative review aims to address the following questions: What is the essence of different dental sealants’ activity, how does their chemical formula affect their mechanisms of caries prevention, and what makes a dental sealant efficient mean of caries prevention? Another vital issue is whether the sealants that contain fluoride, or any other additions, have potentially increased antimicrobial properties. An electronic search of the PubMed, Cochrane, Web of Science, and Scopus databases was performed. The following keywords were used: (dental sealants) AND (chemical composition). Additionally, information about composition and indications for clinical use provided by manufacturers were utilized. All of the considered materials are indicated for use both in permanent and primary dentition for sealing fissures, pits, and foramina caeca. The selection of suitable material should be made individually and adjusted to conditions of the sealing procedure and patient’s needs. Cariostatic mechanisms increasing sealants’ effectiveness such as fluoride release are desired in modern dentistry appreciating preventive approach. The review aims are to find crucial elements of sealants’ composition which affect their cariostatic mechanisms. Full article
(This article belongs to the Special Issue Elements Content and Release from Tissues and Biomaterials In Vivo and In Vitro)
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41 pages, 12583 KiB  
Review
Enhancing Fatigue Life and Strength of Adhesively Bonded Composite Joints: A Comprehensive Review
by Hossein Malekinejad, Ricardo J. C. Carbas, Alireza Akhavan-Safar, Eduardo A. S. Marques, Fernando Castro Sousa and Lucas F. M. da Silva
Materials 2023, 16(19), 6468; https://doi.org/10.3390/ma16196468 - 28 Sep 2023
Cited by 30 | Viewed by 7404
Abstract
Adhesive bonding is widely seen as the most optimal method for joining composite materials, bringing significant benefits over mechanical joining, such as lower weight and reduced stress concentrations. Adhesively bonded composite joints find extensive applications where cyclic fatigue loading takes place, but this [...] Read more.
Adhesive bonding is widely seen as the most optimal method for joining composite materials, bringing significant benefits over mechanical joining, such as lower weight and reduced stress concentrations. Adhesively bonded composite joints find extensive applications where cyclic fatigue loading takes place, but this might ultimately lead to crack damage and safety issues. Consequently, it has become essential to study how these structures behave under fatigue loads and identify the remaining gaps in knowledge to give insights into new possibilities. The fatigue life of adhesively bonded composite joints is influenced by various parameters, including joint configuration and material properties of adherends and adhesive. Numerous studies with varying outcomes have been documented in the literature. However, due to the multitude of influential factors, deriving conclusive insights from these studies for practical design purposes has proven to be challenging. Hence, this review aims to address this challenge by discussing different methods to enhance the fatigue performance of adhesively bonded composite joints. Additionally, it provides a comprehensive overview of the existing literature on adhesively bonded composite joints under cyclic fatigue loading, focusing on three main aspects: Adherends modification, adhesive modification, and joint configurations. Since the effect of modifying the adhesive, adherends, and joint configurations on fatigue performance has not been comprehensively studied in the literature, this review aims to fill this gap by compiling and comparing the relevant experimental data. Furthermore, this review discusses the challenges and limitations associated with the methods that can be used to monitor the initiation and propagation of fatigue cracks. Full article
(This article belongs to the Special Issue Advances in Service Life Evaluation of Metallic and Composite Materials)
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29 pages, 9500 KiB  
Review
Zirconium Carbide for Hypersonic Applications, Opportunities and Challenges
by Glenn R. Peterson, Ryan E. Carr and Ernesto E. Marinero
Materials 2023, 16(18), 6158; https://doi.org/10.3390/ma16186158 - 11 Sep 2023
Cited by 11 | Viewed by 3349
Abstract
At ultra-high temperatures, resilient, durable, stable material choices are limited. While Carbon/Carbon (C/C) composites (carbon fibers and carbon matrix phases) are currently the materials of choice, zirconium carbide (ZrC) provides an option in hypersonic environments and specifically in wing leading edge (WLE) applications. [...] Read more.
At ultra-high temperatures, resilient, durable, stable material choices are limited. While Carbon/Carbon (C/C) composites (carbon fibers and carbon matrix phases) are currently the materials of choice, zirconium carbide (ZrC) provides an option in hypersonic environments and specifically in wing leading edge (WLE) applications. ZrC also offers an ultra-high melting point (3825 K), robust mechanical properties, better thermal conductivity, and potentially better chemical stability and oxidation resistance than C/C composites. In this review, we discuss the mechanisms behind ZrC mechanical, thermal, and chemical properties and evaluate: (a) mechanical properties: flexure strength, fracture toughness, and elastic modulus; (b) thermal properties: coefficient of thermal expansion (CTE), thermal conductivity, and melting temperature; (c) chemical properties: thermodynamic stability and reaction kinetics of oxidation. For WLE applications, ZrC physical properties require further improvements. We note that materials or processing solutions to increase its relative density through sintering aids can have deleterious effects on oxidation resistance. Therefore, improvements of key ZrC properties for WLE applications must not compromise other functional properties. We suggest that C/C-ZrC composites offer an engineering solution to reduce density (weight) for aerospace applications, improve fracture toughness and the mechanical response, while addressing chemical stability and stoichiometric concerns. Recommendations for future work are also given. Full article
(This article belongs to the Special Issue Advances in Functional Ceramic Materials: Fabrication, Properties, and High-Temperature Applications)
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28 pages, 7377 KiB  
Review
A Review of Metamaterials in Wireless Power Transfer
by Cancan Rong, Lihui Yan, Long Li, Yunhui Li and Minghai Liu
Materials 2023, 16(17), 6008; https://doi.org/10.3390/ma16176008 - 31 Aug 2023
Cited by 18 | Viewed by 4123
Abstract
Wireless power transfer (WPT) is a technology that enables energy transmission without physical contact, utilizing magnetic and electric fields as soft media. While WPT has numerous applications, the increasing power transfer distance often results in a decrease in transmission efficiency, as well as [...] Read more.
Wireless power transfer (WPT) is a technology that enables energy transmission without physical contact, utilizing magnetic and electric fields as soft media. While WPT has numerous applications, the increasing power transfer distance often results in a decrease in transmission efficiency, as well as the urgent need for addressing safety concerns. Metamaterials offer a promising way for improving efficiency and reducing the flux density in WPT systems. This paper provides an overview of the current status and technical challenges of metamaterial-based WPT systems. The basic principles of magnetic coupling resonant wireless power transfer (MCR-WPT) are presented, followed by a detailed description of the metamaterial design theory and its application in WPT. The paper then reviews the metamaterial-based wireless energy transmission system from three perspectives: transmission efficiency, misalignment tolerance, and electromagnetic shielding. Finally, the paper summarizes the development trends and technical challenges of metamaterial-based WPT systems. Full article
(This article belongs to the Special Issue Metamaterials for Wireless Power Transfer)
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31 pages, 7958 KiB  
Review
Electrospun Nanofibers for Functional Food Packaging Application
by Meng Zhang, Adnan Ahmed and Lan Xu
Materials 2023, 16(17), 5937; https://doi.org/10.3390/ma16175937 - 30 Aug 2023
Cited by 25 | Viewed by 5420
Abstract
With the strengthening of the public awareness of food safety and environmental protection, functional food packaging materials have received widespread attention. Nanofibers are considered as promising packaging materials due to their unique one-dimensional structure (high aspect ratio, large specific surface area) and functional [...] Read more.
With the strengthening of the public awareness of food safety and environmental protection, functional food packaging materials have received widespread attention. Nanofibers are considered as promising packaging materials due to their unique one-dimensional structure (high aspect ratio, large specific surface area) and functional advantages. Electrospinning, as a commonly used simple and efficient method for preparing nanofibers, can obtain nanofibers with different structures such as aligned, core-shell, and porous structures by modifying the devices and adjusting the process parameters. The selection of raw materials and structural design of nanofibers can endow food packaging with different functions, including antimicrobial activity, antioxidation, ultraviolet protection, and response to pH. This paper aims to provide a comprehensive review of the application of electrospun nanofibers in functional food packaging. Advances in electrospinning technology and electrospun materials used for food packaging are introduced. Moreover, the progress and development prospects of electrospun nanofibers in functional food packaging are highlighted. Meanwhile, the application of functional packaging based on nanofibers in different foods is discussed in detail. Full article
(This article belongs to the Special Issue Functional Cellulosic Materials)
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18 pages, 4899 KiB  
Review
Wearable Temperature Sensors Based on Reduced Graphene Oxide Films
by Xinyue Li, Tianrui Cui, Xin Li, Houfang Liu, Ding Li, Jinming Jian, Zhen Li, Yi Yang and Tianling Ren
Materials 2023, 16(17), 5952; https://doi.org/10.3390/ma16175952 - 30 Aug 2023
Cited by 4 | Viewed by 2469
Abstract
With the development of medical technology and increasing demands of healthcare monitoring, wearable temperature sensors have gained widespread attention because of their portability, flexibility, and capability of conducting real-time and continuous signal detection. To achieve excellent thermal sensitivity, high linearity, and a fast [...] Read more.
With the development of medical technology and increasing demands of healthcare monitoring, wearable temperature sensors have gained widespread attention because of their portability, flexibility, and capability of conducting real-time and continuous signal detection. To achieve excellent thermal sensitivity, high linearity, and a fast response time, the materials of sensors should be chosen carefully. Thus, reduced graphene oxide (rGO) has become one of the most popular materials for temperature sensors due to its exceptional thermal conductivity and sensitive resistance changes in response to different temperatures. Moreover, by using the corresponding preparation methods, rGO can be easily combined with various substrates, which has led to it being extensively applied in the wearable field. This paper reviews the state-of-the-art advances in wearable temperature sensors based on rGO films and summarizes their sensing mechanisms, structure designs, functional material additions, manufacturing processes, and performances. Finally, the possible challenges and prospects of rGO-based wearable temperature sensors are briefly discussed. Full article
(This article belongs to the Special Issue Growth and Applications of Oxide Thin Films and Heterostructures)
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15 pages, 2858 KiB  
Review
Bio-Based Binder Development for Lithium-Ion Batteries
by Illia Dobryden, Céline Montanari, Dhrubajyoti Bhattacharjya, Juhanes Aydin and Anwar Ahniyaz
Materials 2023, 16(16), 5553; https://doi.org/10.3390/ma16165553 - 10 Aug 2023
Cited by 17 | Viewed by 5898
Abstract
The development of rechargeable lithium-ion battery (LIB) technology has facilitated the shift toward electric vehicles and grid storage solutions. This technology is currently undergoing significant development to meet industrial applications for portable electronics and provide our society with “greener” electricity. The large increase [...] Read more.
The development of rechargeable lithium-ion battery (LIB) technology has facilitated the shift toward electric vehicles and grid storage solutions. This technology is currently undergoing significant development to meet industrial applications for portable electronics and provide our society with “greener” electricity. The large increase in LIB production following the growing demand from the automotive sector has led to the establishment of gigafactories worldwide, thus increasing the substantial consumption of fossil-based and non-sustainable materials, such as polyvinylidene fluoride and/or styrene-butadiene rubber as binders in cathode and anode formulations. Furthermore, the use of raw resources, such as Li, Ni, and Mn in cathode active materials and graphite and nanosilicon in anodes, necessitates further efforts to enhance battery efficiency. To foster a global sustainable transition in LIB manufacturing and reduce reliance on non-sustainable materials, the implementation of bio-based binder solutions for electrodes in LIBs is crucial. Bio-based binders such as cellulose, lignin, alginate, gums, starch, and others can address environmental concerns and can enhance LIBs’ performance. This review aims to provide an overview of the current progress in the development and application of bio-based binders for LIB electrode manufacturing, highlighting their significance toward sustainable development. Full article
(This article belongs to the Special Issue Surface/Interface Science of Advanced Energy Conversion and Storage Materials)
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17 pages, 3590 KiB  
Review
Optimization of Spark Plasma Sintering Technology by Taguchi Method in the Production of a Wide Range of Materials: Review
by Robert Kruzel, Tomasz Dembiczak and Joanna Wachowicz
Materials 2023, 16(16), 5539; https://doi.org/10.3390/ma16165539 - 9 Aug 2023
Cited by 7 | Viewed by 2401
Abstract
This paper reviews the production of sinters using the spark plasma sintering method. SPS (spark plasma sintering) technology has been used for several decades, mainly in laboratories, to consolidate a huge number of both new and traditional materials. However, it is now more [...] Read more.
This paper reviews the production of sinters using the spark plasma sintering method. SPS (spark plasma sintering) technology has been used for several decades, mainly in laboratories, to consolidate a huge number of both new and traditional materials. However, it is now more often introduced into practical industrial use, with equipment as early as the fifth generation capable of producing larger-size components at competitive costs. Although the mechanism of sintering with the use of this method is not yet understood, the effectiveness of the SPS process for the rapid and efficient consolidation of a wide range of materials with novel micro-structures remains indisputable. With a relatively wide variation in chemical composition, the structure allows the selection of appropriate consolidation parameters for these materials. The influence on the values of apparent density and mechanical properties depends on the parameters of the spark plasma sintering process. In order to achieve a density close to the theoretical density of sinters, optimization of the sintering parameters, i.e., sintering temperature, heating rate, sintering time, pressing pressure and protective atmosphere, should be carried out. In this paper, the optimization of spark plasma sintering of Si3N4–Al2O3–ZrO2 composite was carried out using the Taguchi method. The effects of four sintering factors, namely heating rate, sintering time, sintering temperature and sintering pressure, on the final density were investigated. Optimal sintering conditions were proposed and a confirmation experiment was conducted. The optimal combination of sintering conditions for spark plasma sintering (SPS) of Si3N4–Al2O3–ZrO2 composite for high apparent density was determined as A3-B3-C3-D2. Based on ANOVA analysis, it was found that the apparent density of sintering was significantly influenced by sintering temperature, followed by pressing pressure, sintering time and heating rate. Validation of the developed mathematical model predicting the apparent density of sinters showed close agreement between the predicted response results and experimental results. Full article
(This article belongs to the Special Issue Advanced Powder Metallurgy Materials and Technology)
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25 pages, 7104 KiB  
Review
Cyclodextrins for Lithium Batteries Applications
by Mohamed M. H. Desoky, Fabrizio Caldera, Valentina Brunella, Riccardo Ferrero, Gjylije Hoti and Francesco Trotta
Materials 2023, 16(16), 5540; https://doi.org/10.3390/ma16165540 - 9 Aug 2023
Cited by 10 | Viewed by 3310
Abstract
Due to their high energy and power density, lithium-ion batteries (LIBs) have gained popularity in response to the demand for effective energy storage solutions. The importance of the electrode architecture in determining battery performance highlights the demand for optimization. By developing useful organic [...] Read more.
Due to their high energy and power density, lithium-ion batteries (LIBs) have gained popularity in response to the demand for effective energy storage solutions. The importance of the electrode architecture in determining battery performance highlights the demand for optimization. By developing useful organic polymers, cyclodextrin architectures have been investigated to improve the performance of Li-based batteries. The macrocyclic oligosaccharides known as cyclodextrins (CDs) have relatively hydrophobic cavities that can enclose other molecules. There are many industries where this “host–guest” relationship has been found useful. The hydrogen bonding and suitable inner cavity diameter of CD have led to its selection as a lithium-ion diffusion channel. CDs have also been used as solid electrolytes for solid-state batteries and as separators and binders to ensure adhesion between electrode components. This review gives a general overview of CD-based materials and how they are used in battery components, highlighting their advantages. Full article
(This article belongs to the Special Issue Cyclodextrins: Aged Materials for New Applications)
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24 pages, 3248 KiB  
Review
Nanoparticles in Cancer Diagnosis and Treatment
by Jaya Baranwal, Brajesh Barse, Amalia Di Petrillo, Gianluca Gatto, Luca Pilia and Amit Kumar
Materials 2023, 16(15), 5354; https://doi.org/10.3390/ma16155354 - 30 Jul 2023
Cited by 63 | Viewed by 5660
Abstract
The use of tailored medication delivery in cancer treatment has the potential to increase efficacy while decreasing unfavourable side effects. For researchers looking to improve clinical outcomes, chemotherapy for cancer continues to be the most challenging topic. Cancer is one of the worst [...] Read more.
The use of tailored medication delivery in cancer treatment has the potential to increase efficacy while decreasing unfavourable side effects. For researchers looking to improve clinical outcomes, chemotherapy for cancer continues to be the most challenging topic. Cancer is one of the worst illnesses despite the limits of current cancer therapies. New anticancer medications are therefore required to treat cancer. Nanotechnology has revolutionized medical research with new and improved materials for biomedical applications, with a particular focus on therapy and diagnostics. In cancer research, the application of metal nanoparticles as substitute chemotherapy drugs is growing. Metals exhibit inherent or surface-induced anticancer properties, making metallic nanoparticles extremely useful. The development of metal nanoparticles is proceeding rapidly and in many directions, offering alternative therapeutic strategies and improving outcomes for many cancer treatments. This review aimed to present the most commonly used nanoparticles for cancer applications. Full article
(This article belongs to the Special Issue Nanomaterials for Medical Application (Second Volume))
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19 pages, 848 KiB  
Review
The Intraoperative Use of Defensive Antibacterial Coating (DAC®) in the Form of a Gel to Prevent Peri-Implant Infections in Orthopaedic Surgery: A Clinical Narrative Review
by Daniele Pressato, Angela Battista, Marco Govoni, Leonardo Vivarelli, Dante Dallari and Antonio Pellegrini
Materials 2023, 16(15), 5304; https://doi.org/10.3390/ma16155304 - 28 Jul 2023
Cited by 6 | Viewed by 2633
Abstract
Periprosthetic joint infections (PJIs) in arthroplasty and osteosynthesis-associated infections (OAIs) in reconstructive surgery still represent a challenging complication in orthopaedics and traumatology causing a burden worsening the patient’s quality of life, for caregiver and treating physicians, and for healthcare systems. PJIs and OAIs [...] Read more.
Periprosthetic joint infections (PJIs) in arthroplasty and osteosynthesis-associated infections (OAIs) in reconstructive surgery still represent a challenging complication in orthopaedics and traumatology causing a burden worsening the patient’s quality of life, for caregiver and treating physicians, and for healthcare systems. PJIs and OAIs are the result of bacterial adhesion over an implant surface with subsequent biofilm formation. Therefore, the clinical pathological outcome is a difficult-to-eradicate persistent infection. Strategies to treat PJIs and OAIs involve debridement, the replacement of internal fixators or articular prostheses, and intravenous antibiotics. However, long treatments and surgical revision cause discomfort for patients; hence, the prevention of PJIs and OAIs represents a higher priority than treatment. Local antibiotic treatments through coating-release systems are becoming a smart approach to prevent this complication. Hydrophilic coatings, loaded with antibiotics, simultaneously provide a barrier effect against bacterial adhesion and allow for the local delivery of an antibiotic. The intraoperative use of a hyaluronan (HY)-derivative coating in the form of a gel, loaded with antibiotics to prevent PJI, has recently raised interest in orthopaedics. Current evidence supports the use of this coating in the prophylaxis of PJI and IRIs in terms of clinical outcomes and infection reduction. Thus, the purpose of this narrative review is to assess the use of a commercially available HY derivative in the form of a gel, highlighting the characteristics of this biomaterial, which makes it attractive for the management of PJIs and IRIs in orthopaedics and traumatology. Full article
(This article belongs to the Special Issue Synthetic and Biologic Materials for Prosthetic and Reconstructive Applications for Musculoskeletal Tissue)
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25 pages, 3730 KiB  
Review
Recent Advances in the Synthesis and Application of Vacancy-Ordered Halide Double Perovskite Materials for Solar Cells: A Promising Alternative to Lead-Based Perovskites
by Santhosh Murugan and Eun-Cheol Lee
Materials 2023, 16(15), 5275; https://doi.org/10.3390/ma16155275 - 27 Jul 2023
Cited by 17 | Viewed by 4794
Abstract
Lead-based halide perovskite materials are being developed as efficient light-absorbing materials for use in perovskite solar cells (PSCs). PSCs have shown remarkable progress in power conversion efficiency, increasing from 3.80% to more than 25% within a decade, showcasing their potential as a promising [...] Read more.
Lead-based halide perovskite materials are being developed as efficient light-absorbing materials for use in perovskite solar cells (PSCs). PSCs have shown remarkable progress in power conversion efficiency, increasing from 3.80% to more than 25% within a decade, showcasing their potential as a promising renewable energy technology. Although PSCs have many benefits, including a high light absorption coefficient, the ability to tune band gap, and a long charge diffusion length, the poor stability and the toxicity of lead represent a significant disadvantage for commercialization. To address this issue, research has focused on developing stable and nontoxic halide perovskites for use in solar cells. A potential substitute is halide double perovskites (HDPs), particularly vacancy-ordered HDPs, as they offer greater promise because they can be processed using a solution-based method. This review provides a structural analysis of HDPs, the various synthesis methods for vacancy-ordered HDPs, and their impact on material properties. Recent advances in vacancy-ordered HDPs are also discussed, including their role in active and transport layers of solar cells. Furthermore, valuable insights for developing high-performance vacancy-ordered HDP solar cells are reported from the detailed information presented in recent simulation studies. Finally, the potential of vacancy-ordered HDPs as a substitute for lead-based perovskites is outlined. Overall, the ability to tune optical and electronic properties and the high stability and nontoxicity of HDPs have positioned them as a promising candidate for use in photovoltaic applications. Full article
(This article belongs to the Special Issue Advanced Nanostructured Materials for Solar Energy Conversion)
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20 pages, 5922 KiB  
Review
Asymmetric Extrusion Technology of Mg Alloy: A Review
by Qingshan Yang, Dan Zhang, Peng Peng, Guobing Wei, Jianyue Zhang, Bin Jiang and Fusheng Pan
Materials 2023, 16(15), 5255; https://doi.org/10.3390/ma16155255 - 26 Jul 2023
Cited by 8 | Viewed by 2215
Abstract
Magnesium (Mg) alloy is a widely used lightweight metal structural material due to its high specific strength and stiffness, excellent damping performance, and recyclability. Wrought Mg alloys are particularly favored in fields such as aerospace, transportation, and biomedical stents. However, most wrought Mg [...] Read more.
Magnesium (Mg) alloy is a widely used lightweight metal structural material due to its high specific strength and stiffness, excellent damping performance, and recyclability. Wrought Mg alloys are particularly favored in fields such as aerospace, transportation, and biomedical stents. However, most wrought Mg alloys with a hexagonal close-packed (HCP) crystal structure lack sufficient independent slip systems to meet the von Mises criterion for uniform plastic deformation at room temperature. This can result in the formation of a strong basal texture during plastic deformation and poor room temperature plastic formability. Enhancing the room temperature forming performance is therefore a crucial challenge that needs to be addressed in order to expand the application of Mg alloy sheets. Our research group has comprehensively summarized significant work and the latest research progress in improving the room temperature forming of Mg alloy sheets via extrusion technology in recent years. Specifically, we have developed a new type of asymmetric extrusion technology that combines material structure evolution, mechanical properties, and forming behavior analysis. We have elucidated the extrusion process characteristics, texture control mechanism, and forming properties of Mg alloy sheets through plastic deformation mechanisms, mold design, and finite element numerical simulation. The findings of our study present an innovative extrusion technology for the fabrication of highly formable Mg alloy sheets, which can be utilized in various applications. Full article
(This article belongs to the Special Issue Microstructure, Mechanical Properties, and Deformation Characteristics of Metals and Alloys)
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35 pages, 33012 KiB  
Review
Dynamic Hydrogels with Viscoelasticity and Tunable Stiffness for the Regulation of Cell Behavior and Fate
by Yuhang Zhang, Zhuofan Wang, Qingqing Sun, Qian Li, Shaohui Li and Xiaomeng Li
Materials 2023, 16(14), 5161; https://doi.org/10.3390/ma16145161 - 21 Jul 2023
Cited by 22 | Viewed by 5491
Abstract
The extracellular matrix (ECM) of natural cells typically exhibits dynamic mechanical properties (viscoelasticity and dynamic stiffness). The viscoelasticity and dynamic stiffness of the ECM play a crucial role in biological processes, such as tissue growth, development, physiology, and disease. Hydrogels with viscoelasticity and [...] Read more.
The extracellular matrix (ECM) of natural cells typically exhibits dynamic mechanical properties (viscoelasticity and dynamic stiffness). The viscoelasticity and dynamic stiffness of the ECM play a crucial role in biological processes, such as tissue growth, development, physiology, and disease. Hydrogels with viscoelasticity and dynamic stiffness have recently been used to investigate the regulation of cell behavior and fate. This article first emphasizes the importance of tissue viscoelasticity and dynamic stiffness and provides an overview of characterization techniques at both macro- and microscale. Then, the viscoelastic hydrogels (crosslinked via ion bonding, hydrogen bonding, hydrophobic interactions, and supramolecular interactions) and dynamic stiffness hydrogels (softening, stiffening, and reversible stiffness) with different crosslinking strategies are summarized, along with the significant impact of viscoelasticity and dynamic stiffness on cell spreading, proliferation, migration, and differentiation in two-dimensional (2D) and three-dimensional (3D) cell cultures. Finally, the emerging trends in the development of dynamic mechanical hydrogels are discussed. Full article
(This article belongs to the Special Issue Feature Paper in the Section 'Polymeric Materials' (2nd Edition))
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26 pages, 4639 KiB  
Review
A Review on Multiple I-III-VI Quantum Dots: Preparation and Enhanced Luminescence Properties
by Ting Chen, Yuanhong Chen, Youpeng Li, Mengbiao Liang, Wenkui Wu and Yude Wang
Materials 2023, 16(14), 5039; https://doi.org/10.3390/ma16145039 - 17 Jul 2023
Cited by 18 | Viewed by 3744
Abstract
I-III-VI type QDs have unique optoelectronic properties such as low toxicity, tunable bandgaps, large Stokes shifts and a long photoluminescence lifetime, and their emission range can be continuously tuned in the visible to near-infrared light region by changing their chemical composition. Moreover, they [...] Read more.
I-III-VI type QDs have unique optoelectronic properties such as low toxicity, tunable bandgaps, large Stokes shifts and a long photoluminescence lifetime, and their emission range can be continuously tuned in the visible to near-infrared light region by changing their chemical composition. Moreover, they can avoid the use of heavy metal elements such as Cd, Hg and Pb and highly toxic anions, i.e., Se, Te, P and As. These advantages make them promising candidates to replace traditional binary QDs in applications such as light-emitting diodes, solar cells, photodetectors, bioimaging fields, etc. Compared with binary QDs, multiple QDs contain many different types of metal ions. Therefore, the problem of different reaction rates between the metal ions arises, causing more defects inside the crystal and poor fluorescence properties of QDs, which can be effectively improved by doping metal ions (Zn2+, Mn2+ and Cu+) or surface coating. In this review, the luminous mechanism of I-III-VI type QDs based on their structure and composition is introduced. Meanwhile, we focus on the various synthesis methods and improvement strategies like metal ion doping and surface coating from recent years. The primary applications in the field of optoelectronics are also summarized. Finally, a perspective on the challenges and future perspectives of I-III-VI type QDs is proposed as well. Full article
(This article belongs to the Special Issue Advances of Photoelectric Functional Materials and Devices)
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19 pages, 2788 KiB  
Review
Computational Materials Design for Ceramic Nuclear Waste Forms Using Machine Learning, First-Principles Calculations, and Kinetics Rate Theory
by Jianwei Wang, Dipta B. Ghosh and Zelong Zhang
Materials 2023, 16(14), 4985; https://doi.org/10.3390/ma16144985 - 13 Jul 2023
Cited by 6 | Viewed by 2310
Abstract
Ceramic waste forms are designed to immobilize radionuclides for permanent disposal in geological repositories. One of the principal criteria for the effective incorporation of waste elements is their compatibility with the host material. In terms of performance under environmental conditions, the resistance of [...] Read more.
Ceramic waste forms are designed to immobilize radionuclides for permanent disposal in geological repositories. One of the principal criteria for the effective incorporation of waste elements is their compatibility with the host material. In terms of performance under environmental conditions, the resistance of the waste forms to degradation over long periods of time is a critical concern when they are exposed to natural environments. Due to their unique crystallographic features and behavior in nature environment as exemplified by their natural analogues, ceramic waste forms are capable of incorporating problematic nuclear waste elements while showing promising chemical durability in aqueous environments. Recent studies of apatite- and hollandite-structured waste forms demonstrated an approach that can predict the compositions of ceramic waste forms and their long-term dissolution rate by a combination of computational techniques including machine learning, first-principles thermodynamics calculations, and modeling using kinetic rate equations based on critical laboratory experiments. By integrating the predictions of elemental incorporation and degradation kinetics in a holistic framework, the approach could be promising for the design of advanced ceramic waste forms with optimized incorporation capacity and environmental degradation performance. Such an approach could provide a path for accelerated ceramic waste form development and performance prediction for problematic nuclear waste elements. Full article
(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Chemistry)
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20 pages, 9160 KiB  
Review
Review of Single Crystal Synthesis of 11 Iron-Based Superconductors
by Qiang Hou, Longfei Sun, Yue Sun and Zhixiang Shi
Materials 2023, 16(14), 4895; https://doi.org/10.3390/ma16144895 - 8 Jul 2023
Cited by 4 | Viewed by 2796
Abstract
The 11 system in the iron-based superconducting family has become one of the most extensively studied materials in the research of high-temperature superconductivity, due to their simple structure and rich physical properties. Many exotic properties, such as multiband electronic structure, electronic nematicity, topology [...] Read more.
The 11 system in the iron-based superconducting family has become one of the most extensively studied materials in the research of high-temperature superconductivity, due to their simple structure and rich physical properties. Many exotic properties, such as multiband electronic structure, electronic nematicity, topology and antiferromagnetic order, provide strong support for the theory of high-temperature superconductivity, and have been at the forefront of condensed matter physics in the past decade. One noteworthy aspect is that a high upper critical magnetic field, large critical current density and lower toxicity give the 11 system good application prospects. However, the research on 11 iron-based superconductors faces numerous obstacles, mainly stemming from the challenges associated with producing high-quality single crystals. Since the discovery of FeSe superconductivity in 2008, researchers have made significant progress in crystal growth, overcoming the hurdles that initially impeded their studies. Consequently, they have successfully established the complete phase diagrams of 11 iron-based superconductors, including FeSe1−xTex, FeSe1−xSx and FeTe1−xSx. In this paper, we aim to provide a comprehensive summary of the preparation methods employed for 11 iron-based single crystals over the past decade. Specifically, we will focus on hydrothermal, chemical vapor transport (CVT), self-flux and annealing methods. Additionally, we will discuss the quality, size, and superconductivity properties exhibited by single crystals obtained through different preparation methods. By exploring these aspects, we can gain a better understanding of the advantages and limitations associated with each technique. High-quality single crystals serve as invaluable tools for advancing both the theoretical understanding and practical utilization of high-temperature superconductivity. Full article
(This article belongs to the Special Issue Physics and Application of Superconductivity)
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25 pages, 23142 KiB  
Review
Significant Progress for Hot-Deformed Nd-Fe-B Magnets: A Review
by Renjie Chen, Xianshuang Xia, Xu Tang and Aru Yan
Materials 2023, 16(13), 4789; https://doi.org/10.3390/ma16134789 - 3 Jul 2023
Cited by 12 | Viewed by 4344
Abstract
High-performance Nd-Fe-B-based rare-earth permanent magnets play a crucial role in the application of traction motors equipped in new energy automobiles. In particular, the anisotropic hot-deformed (HD) Nd-Fe-B magnets prepared by the hot-press and hot-deformation process show great potential in achieving high coercivity due [...] Read more.
High-performance Nd-Fe-B-based rare-earth permanent magnets play a crucial role in the application of traction motors equipped in new energy automobiles. In particular, the anisotropic hot-deformed (HD) Nd-Fe-B magnets prepared by the hot-press and hot-deformation process show great potential in achieving high coercivity due to their fine grain sizes of 200–400 nm, which are smaller by more than an order of magnitude compared to the traditional sintered Nd-Fe-B magnets. However, the current available coercivity of HD magnets is not as high as expected according to an empirical correlation between coercivity and grain size, only occupying about 25% of its full potential of the anisotropy field of the Nd2Fe14B phase. For the sake of achieving high-coercivity HD magnets, two major routes have been developed, namely the grain boundary diffusion process (GBDP) and the dual alloy diffusion process (DADP). In this review, the fundamentals and development of the HD Nd-Fe-B magnets are comprehensively summarized and discussed based on worldwide scientific research. The advances in the GBDP and DADP are investigated and summarized based on the latest progress and results. Additionally, the mechanisms of coercivity enhancement are discussed based on the numerous results of micromagnetic simulations to understand the structure–property relationships of the HD Nd-Fe-B magnets. Lastly, the magnetization reversal behaviors, based on the observation of magneto-optic Kerr effect microscopy, are analyzed to pinpoint the weak regions in the microstructure of the HD Nd-Fe-B magnets. Full article
(This article belongs to the Special Issue Fabrication, Characterization, and Development of Hot-Deformed Magnets)
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28 pages, 35152 KiB  
Review
The Role of Lithium in the Aging Precipitation Process of Al-Zn-Mg-Cu Alloys and Its Effect on the Properties
by Jing-Ran Sun, Bai-Xin Dong, Hong-Yu Yang, Shi-Li Shu, Feng Qiu, Qi-Chuan Jiang and Lai-Chang Zhang
Materials 2023, 16(13), 4750; https://doi.org/10.3390/ma16134750 - 30 Jun 2023
Cited by 2 | Viewed by 2416
Abstract
It is well known that the development of lightweight alloys with improved comprehensive performance and application value are the future development directions for the ultra-high-strength 7xxx series Al-Zn-Mg-Cu alloys used in the aircraft field. As the lightest metal element in nature, lithium (Li) [...] Read more.
It is well known that the development of lightweight alloys with improved comprehensive performance and application value are the future development directions for the ultra-high-strength 7xxx series Al-Zn-Mg-Cu alloys used in the aircraft field. As the lightest metal element in nature, lithium (Li) has outstanding advantages in reducing the density and increasing the elastic modulus in aluminum alloys, so Al-Zn-Mg-Cu alloys containing Li have gained widespread attention. Furthermore, since the Al-Zn-Mg-Cu alloy is usually strengthened by aging treatment, it is crucial to understand how Li addition affects its aging precipitation process. As such, in this article, the effects and mechanism of Li on the aging precipitation behavior and the impact of Li content on the aging precipitation phase of Al-Zn-Mg-Cu alloys are briefly reviewed, and the influence of Li on the service properties, including mechanical properties, wear resistance, and fatigue resistance, of Al-Zn-Mg-Cu alloys are explained. In addition, the corresponding development prospects and challenges of the Al-Zn-Mg-Cu-Li alloy are also proposed. This review is helpful to further understand the role of Li in Al-Zn-Mg-Cu alloys and provides a reference for the development of high-strength aluminum alloys containing Li with good comprehensive properties. Full article
(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)
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18 pages, 885 KiB  
Review
Effect of Thermal Treatments and Ion Substitution on Sintering and Crystallization of Bioactive Glasses: A Review
by Francesco Gerardo Mecca, Devis Bellucci and Valeria Cannillo
Materials 2023, 16(13), 4651; https://doi.org/10.3390/ma16134651 - 28 Jun 2023
Cited by 15 | Viewed by 2712
Abstract
Bioactive glasses (BGs) are promising materials for bone regeneration due to their ability to bond with living bone tissue. However, thermal stability and mechanical properties of BGs need improvement for better clinical performance. In this paper, we present an overview of the influence [...] Read more.
Bioactive glasses (BGs) are promising materials for bone regeneration due to their ability to bond with living bone tissue. However, thermal stability and mechanical properties of BGs need improvement for better clinical performance. In this paper, we present an overview of the influence of different ions on the sintering and crystallization of BGs. Specifically, this review focuses on the impact of thermal treatments on the crystallization of 45S5 and other significant BG compositions. Potential applications of these thermally treated BGs, such as scaffolds, BG-based composites, and thermally sprayed coatings, are explored. Moreover, the substitution of ions has been investigated as a method to enhance the thermal properties of BGs. Notably, zinc, potassium, and strontium have been studied extensively and have demonstrated promising effects on both the thermal and the mechanical properties of BGs. However, it is important to note that research on ion inclusion in BGs is still in its early stages, and further investigation is necessary to fully comprehend the effects of different ions on sintering and crystallization. Therefore, future studies should focus on optimizing the ion substitution method to improve the thermal, mechanical, and even biological properties of BGs, thereby enhancing their potential for various biomedical applications. Full article
(This article belongs to the Special Issue Preparation, Characteristics and Application of Bioactive Glass)
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35 pages, 10639 KiB  
Review
A Review on Controlling Grain Boundary Character Distribution during Twinning-Related Grain Boundary Engineering of Face-Centered Cubic Materials
by Yu-Qing Zhang, Guo-Zheng Quan, Jiang Zhao, Yan-Ze Yu and Wei Xiong
Materials 2023, 16(13), 4562; https://doi.org/10.3390/ma16134562 - 24 Jun 2023
Cited by 12 | Viewed by 3785
Abstract
Grain boundary engineering (GBE) is considered to be an attractive approach to microstructure control, which significantly enhances the grain-boundary-related properties of face-centered cubic (FCC) metals. During the twinning-related GBE, the microstructures are characterized as abundant special twin boundaries that sufficiently disrupt the connectivity [...] Read more.
Grain boundary engineering (GBE) is considered to be an attractive approach to microstructure control, which significantly enhances the grain-boundary-related properties of face-centered cubic (FCC) metals. During the twinning-related GBE, the microstructures are characterized as abundant special twin boundaries that sufficiently disrupt the connectivity of the random boundary network. However, controlling the grain boundary character distribution (GBCD) is an extremely difficult issue, as it strongly depends on diverse processing parameters. This article provides a comprehensive review of controlling GBCD during the twinning-related GBE of FCC materials. To commence, this review elaborates on the theory of twinning-related GBE, the microscopic mechanisms used in the optimization of GBCD, and the optimization objectives of GBCD. Aiming to achieve control over the GBCD, the influence of the initial microstructure, thermo-mechanical processing (TMP) routes, and thermal deformation parameters on the twinning-related microstructures and associated evolution mechanisms are discussed thoroughly. Especially, the development of twinning-related kinetics models for predicting the evolution of twin density is highlighted. Furthermore, this review addresses the applications of twinning-related GBE in enhancing the mechanical properties and corrosion resistance of FCC materials. Finally, future prospects in terms of controlling the GBCD during twinning-related GBE are proposed. This study will contribute to optimizing the GBCD and designing GBE routes for better grain-boundary-related properties in terms of FCC materials. Full article
(This article belongs to the Special Issue Research on Heat Treatment of Advanced Metallic Materials (2nd Volume))
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29 pages, 3044 KiB  
Review
Perspectives on Thermochemical Recycling of End-of-Life Plastic Wastes to Alternative Fuels
by Sonil Nanda, Tumpa R. Sarker, Kang Kang, Dongbing Li and Ajay K. Dalai
Materials 2023, 16(13), 4563; https://doi.org/10.3390/ma16134563 - 24 Jun 2023
Cited by 17 | Viewed by 5635
Abstract
Due to its resistance to natural degradation and decomposition, plastic debris perseveres in the environment for centuries. As a lucrative material for packing industries and consumer products, plastics have become one of the major components of municipal solid waste today. The recycling of [...] Read more.
Due to its resistance to natural degradation and decomposition, plastic debris perseveres in the environment for centuries. As a lucrative material for packing industries and consumer products, plastics have become one of the major components of municipal solid waste today. The recycling of plastics is becoming difficult due to a lack of resource recovery facilities and a lack of efficient technologies to separate plastics from mixed solid waste streams. This has made oceans the hotspot for the dispersion and accumulation of plastic residues beyond landfills. This article reviews the sources, geographical occurrence, characteristics and recyclability of different types of plastic waste. This article presents a comprehensive summary of promising thermochemical technologies, such as pyrolysis, liquefaction and gasification, for the conversion of single-use plastic wastes to clean fuels. The operating principles, drivers and barriers for plastic-to-fuel technologies via pyrolysis (non-catalytic, catalytic, microwave and plasma), as well as liquefaction and gasification, are thoroughly discussed. Thermochemical co-processing of plastics with other organic waste biomass to produce high-quality fuel and energy products is also elaborated upon. Through this state-of-the-art review, it is suggested that, by investing in the research and development of thermochemical recycling technologies, one of the most pragmatic issues today, i.e., plastics waste management, can be sustainably addressed with a greater worldwide impact. Full article
(This article belongs to the Special Issue Plastic Waste Management for Environmental Protection)
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31 pages, 45264 KiB  
Review
Porous Material (Titanium Gas Diffusion Layer) in Proton Exchange Membrane Fuel Cell/Electrolyzer: Fabrication Methods & GeoDict: A Critical Review
by Javid Hussain, Dae-Kyeom Kim, Sangmin Park, Muhammad-Waqas Khalid, Sayed-Sajid Hussain, Bin Lee, Myungsuk Song and Taek-Soo Kim
Materials 2023, 16(13), 4515; https://doi.org/10.3390/ma16134515 - 21 Jun 2023
Cited by 10 | Viewed by 4490
Abstract
Proton exchange membrane fuel cell (PEMFC) is a renewable energy source rapidly approaching commercial viability. The performance is significantly affected by the transfer of fluid, charges, and heat; gas diffusion layer (GDL) is primarily concerned with the consistent transfer of these components, which [...] Read more.
Proton exchange membrane fuel cell (PEMFC) is a renewable energy source rapidly approaching commercial viability. The performance is significantly affected by the transfer of fluid, charges, and heat; gas diffusion layer (GDL) is primarily concerned with the consistent transfer of these components, which are heavily influenced by the material and design. High-efficiency GDL must have excellent thermal conductivity, electrical conductivity, permeability, corrosion resistance, and high mechanical characteristics. The first step in creating a high-performance GDL is selecting the appropriate material. Therefore, titanium is a suitable substitute for steel or carbon due to its high strength-to-weight and superior corrosion resistance. The second crucial parameter is the fabrication method that governs all the properties. This review seeks to comprehend numerous fabrication methods such as tape casting, 3D printing, freeze casting, phase separation technique, and lithography, along with the porosity controller in each process such as partial sintering, input design, ice structure, pore agent, etching time, and mask width. Moreover, other GDL properties are being studied, including microstructure and morphology. In the future, GeoDict simulation is highly recommended for optimizing various GDL properties, as it is frequently used for other porous materials. The approach can save time and energy compared to intensive experimental work. Full article
(This article belongs to the Special Issue Design, Synthesis and Characterization of Novel Porous Materials)
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24 pages, 2090 KiB  
Review
Bioengineering Composite Aerogel-Based Scaffolds That Influence Porous Microstructure, Mechanical Properties and In Vivo Regeneration for Bone Tissue Application
by Mariana Souto-Lopes, Maria Helena Fernandes, Fernando Jorge Monteiro and Christiane Laranjo Salgado
Materials 2023, 16(12), 4483; https://doi.org/10.3390/ma16124483 - 20 Jun 2023
Cited by 9 | Viewed by 2474
Abstract
Tissue regeneration of large bone defects is still a clinical challenge. Bone tissue engineering employs biomimetic strategies to produce graft composite scaffolds that resemble the bone extracellular matrix to guide and promote osteogenic differentiation of the host precursor cells. Aerogel-based bone scaffold preparation [...] Read more.
Tissue regeneration of large bone defects is still a clinical challenge. Bone tissue engineering employs biomimetic strategies to produce graft composite scaffolds that resemble the bone extracellular matrix to guide and promote osteogenic differentiation of the host precursor cells. Aerogel-based bone scaffold preparation methods have been increasingly improved to overcome the difficulties in balancing the need for an open highly porous and hierarchically organized microstructure with compression resistance to withstand bone physiological loads, especially in wet conditions. Moreover, these improved aerogel scaffolds have been implanted in vivo in critical bone defects, in order to test their bone regeneration potential. This review addresses recently published studies on aerogel composite (organic/inorganic)-based scaffolds, having in mind the various cutting-edge technologies and raw biomaterials used, as well as the improvements that are still a challenge in terms of their relevant properties. Finally, the lack of 3D in vitro models of bone tissue for regeneration studies is emphasized, as well as the need for further developments to overcome and minimize the requirement for studies using in vivo animal models. Full article
(This article belongs to the Special Issue Advance in Biomaterials for Tissue Engineering)
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31 pages, 3411 KiB  
Review
Graphene-Based Materials for the Separator Functionalization of Lithium-Ion/Metal/Sulfur Batteries
by Zongle Huang, Wenting Sun, Zhipeng Sun, Rui Ding and Xuebin Wang
Materials 2023, 16(12), 4449; https://doi.org/10.3390/ma16124449 - 18 Jun 2023
Cited by 12 | Viewed by 3674
Abstract
With the escalating demand for electrochemical energy storage, commercial lithium-ion and metal battery systems have been increasingly developed. As an indispensable component of batteries, the separator plays a crucial role in determining their electrochemical performance. Conventional polymer separators have been extensively investigated over [...] Read more.
With the escalating demand for electrochemical energy storage, commercial lithium-ion and metal battery systems have been increasingly developed. As an indispensable component of batteries, the separator plays a crucial role in determining their electrochemical performance. Conventional polymer separators have been extensively investigated over the past few decades. Nevertheless, their inadequate mechanical strength, deficient thermal stability, and constrained porosity constitute serious impediments to the development of electric vehicle power batteries and the progress of energy storage devices. Advanced graphene-based materials have emerged as an adaptable solution to these challenges, owing to their exceptional electrical conductivity, large specific surface area, and outstanding mechanical properties. Incorporating advanced graphene-based materials into the separator of lithium-ion and metal batteries has been identified as an effective strategy to overcome the aforementioned issues and enhance the specific capacity, cycle stability, and safety of batteries. This review paper provides an overview of the preparation of advanced graphene-based materials and their applications in lithium-ion, lithium-metal, and lithium-sulfur batteries. It systematically elaborates on the advantages of advanced graphene-based materials as novel separator materials and outlines future research directions in this field. Full article
(This article belongs to the Section Carbon Materials)
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14 pages, 1284 KiB  
Review
Natural Plant-Derived Compounds in Food and Cosmetics: A Paradigm of Shikonin and Its Derivatives
by Sonia Malik, Patrycja Brudzyńska, Muhammad Rehan Khan, Oksana Sytar, Abdullah Makhzoum and Alina Sionkowska
Materials 2023, 16(12), 4377; https://doi.org/10.3390/ma16124377 - 14 Jun 2023
Cited by 23 | Viewed by 4560
Abstract
Shikonin and its derivatives are the natural naphthoquinone compounds produced in the roots of the Boraginaceae family. These red pigments have been used for a long time in coloring silk, as food colorants, and in the Chinese traditional system of medicines The resurgence [...] Read more.
Shikonin and its derivatives are the natural naphthoquinone compounds produced in the roots of the Boraginaceae family. These red pigments have been used for a long time in coloring silk, as food colorants, and in the Chinese traditional system of medicines The resurgence of public interest in natural and plant-based products has led to this category of compounds being in high demand due to their wide range of biological activities including antioxidant, antitumor, antifungal, anti-inflammatory ones. Different researchers worldwide have reported various applications of shikonin derivatives in the area of pharmacology. Nevertheless, the use of these compounds in the food and cosmetics fields needs to be explored more in order to make them available for commercial utilization in various food industries as a packaging material and to enhance their shelf life without any side effects. Similarly, the antioxidant properties and skin whitening effects of these bioactive molecules may be used successfully in various cosmetic formulations. The present review delves into the updated knowledge on the various properties of shikonin derivatives in relation to food and cosmetics. The pharmacological effects of these bioactive compounds are also highlighted. Based on various studies, it can be concluded that these natural bioactive molecules have potential to be used in different sectors, including functional food, food additives, skin, health care, and to cure various diseases. Further research is required for the sustainable production of these compounds with minimum disturbances to the environment and in order to make them available in the market at an economic price. Simultaneous studies utilizing recent techniques in computational biology, bioinformatics, molecular docking, and artificial intelligence in laboratory and clinical trials would further help in making these potential candidates promising alternative natural bioactive therapeutics with multiple uses. Full article
(This article belongs to the Special Issue Trends in Materials for Cosmetic Formulations)
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27 pages, 2997 KiB  
Review
Optical Second Harmonic Generation on LaAlO3/SrTiO3 Interfaces: A Review
by Andrea Rubano and Domenico Paparo
Materials 2023, 16(12), 4337; https://doi.org/10.3390/ma16124337 - 12 Jun 2023
Cited by 2 | Viewed by 2857
Abstract
As we approach the limits of semiconductor technology, the development of new materials and technologies for the new era in electronics is compelling. Among others, perovskite oxide hetero-structures are anticipated to be the best candidates. As in the case of semiconductors, the interface [...] Read more.
As we approach the limits of semiconductor technology, the development of new materials and technologies for the new era in electronics is compelling. Among others, perovskite oxide hetero-structures are anticipated to be the best candidates. As in the case of semiconductors, the interface between two given materials can have, and often has, very different properties, compared to the corresponding bulk compounds. Perovskite oxides show spectacular interfacial properties due to the the rearrangement of charges, spins, orbitals and the lattice structure itself, at the interface. Lanthanum aluminate and Strontium titanate hetero-structures (LaAlO3/SrTiO3) can be regarded as a prototype of this wider class of interfaces. Both bulk compounds are plain and (relatively) simple wide-bandgap insulators. Despite this, a conductive two-dimensional electron gas (2DEG) is formed right at the interface when a LaAlO3 thickness of n≥4 unit cells is deposited on a SrTiO3 substrate. The 2DEG is quite thin, being confined in only one or at least very few mono-layers at the interface, on the SrTiO3 side. A very intense and long-lasting study was triggered by this surprising discovery. Many questions regarding the origin and characteristics of the two-dimensional electron gas have been (partially) addressed, others are still open. In particular, this includes the interfacial electronic band structure, the transverse plane spatial homogeneity of the samples and the ultrafast dynamics of the confined carriers. Among a very long list of experimental techniques which have been exploited to study these types of interfaces (ARPES, XPS, AFM, PFM, …and many others), optical Second Harmonic Generation (SHG) was found to be suitable for investigating these types of buried interfaces, thanks to its extreme and selective interface-only sensitivity. The SHG technique has made its contribution to the research in this field in a variety of different and important aspects. In this work we will give a bird’s eye view of the currently available research on this topic and try to sketch out its future perspectives. Full article
(This article belongs to the Special Issue Advanced Thin Films and 2D Materials: Mechanism, Fabrication, Characterization and Application)
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23 pages, 4413 KiB  
Review
Copper-Based Electrocatalysts for Nitrate Reduction to Ammonia
by Jia-Yi Fang, Jin-Long Fan, Sheng-Bo Liu, Sheng-Peng Sun and Yao-Yin Lou
Materials 2023, 16(11), 4000; https://doi.org/10.3390/ma16114000 - 26 May 2023
Cited by 31 | Viewed by 6034
Abstract
Ammonia (NH3) is a highly important industrial chemical used as fuel and fertilizer. The industrial synthesis of NH3 relies heavily on the Haber–Bosch route, which accounts for roughly 1.2% of global annual CO2 emissions. As an alternative route, the [...] Read more.
Ammonia (NH3) is a highly important industrial chemical used as fuel and fertilizer. The industrial synthesis of NH3 relies heavily on the Haber–Bosch route, which accounts for roughly 1.2% of global annual CO2 emissions. As an alternative route, the electrosynthesis of NH3 from nitrate anion (NO3−) reduction (NO3−RR) has drawn increasing attention, since NO3−RR from wastewater to produce NH3 can not only recycle waste into treasure but also alleviate the adverse effects of excessive NO3− contamination in the environment. This review presents contemporary views on the state of the art in electrocatalytic NO3− reduction over Cu-based nanostructured materials, discusses the merits of electrocatalytic performance, and summarizes current advances in the exploration of this technology using different strategies for nanostructured-material modification. The electrocatalytic mechanism of nitrate reduction is also reviewed here, especially with regard to copper-based catalysts. Full article
(This article belongs to the Special Issue Electrochemical Materials and Devices for Energy Conversion and Storage)
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23 pages, 2594 KiB  
Review
Advancement of Nonwoven Fabrics in Personal Protective Equipment
by Dhanya Venkataraman, Elnaz Shabani and Jay H. Park
Materials 2023, 16(11), 3964; https://doi.org/10.3390/ma16113964 - 25 May 2023
Cited by 31 | Viewed by 7182
Abstract
While nonwoven fabrics have existed for several decades, their usage in personal protective equipment (PPE) has been met with a rapid surge of demands, in part due to the recent COVID-19 pandemic. This review aims to critically examine the current state of nonwoven [...] Read more.
While nonwoven fabrics have existed for several decades, their usage in personal protective equipment (PPE) has been met with a rapid surge of demands, in part due to the recent COVID-19 pandemic. This review aims to critically examine the current state of nonwoven PPE fabrics by exploring (i) the material constituents and processing steps to produce fibers and bond them, and (ii) how each fabric layer is integrated into a textile, and how the assembled textiles are used as PPE. Firstly, filament fibers are manufactured via dry, wet, and polymer-laid fiber spinning methods. Then the fibers are bonded via chemical, thermal, and mechanical means. Emergent nonwoven processes such as electrospinning and centrifugal spinning to produce unique ultrafine nanofibers are discussed. Nonwoven PPE applications are categorized as filters, medical usage, and protective garments. The role of each nonwoven layer, its role, and textile integration are discussed. Finally, the challenges stemming from the single-use nature of nonwoven PPEs are discussed, especially in the context of growing concerns over sustainability. Then, emerging solutions to address sustainability issues with material and processing innovations are explored. Full article
(This article belongs to the Special Issue Advances in High-Performance Functional Nonwovens)
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22 pages, 3849 KiB  
Review
A Review on Sustainable Inks for Printed Electronics: Materials for Conductive, Dielectric and Piezoelectric Sustainable Inks
by Leire Sanchez-Duenas, Estibaliz Gomez, Mikel Larrañaga, Miren Blanco, Amaia M. Goitandia, Estibaliz Aranzabe and José Luis Vilas-Vilela
Materials 2023, 16(11), 3940; https://doi.org/10.3390/ma16113940 - 24 May 2023
Cited by 32 | Viewed by 7351
Abstract
In the last decades, the demand for electronics and, therefore, electronic waste, has increased. To reduce this electronic waste and the impact of this sector on the environment, it is necessary to develop biodegradable systems using naturally produced materials with low impact on [...] Read more.
In the last decades, the demand for electronics and, therefore, electronic waste, has increased. To reduce this electronic waste and the impact of this sector on the environment, it is necessary to develop biodegradable systems using naturally produced materials with low impact on the environment or systems that can degrade in a certain period. One way to manufacture these types of systems is by using printed electronics because the inks and the substrates used are sustainable. Printed electronics involve different methods of deposition, such as screen printing or inkjet printing. Depending on the method of deposition selected, the developed inks should have different properties, such as viscosity or solid content. To produce sustainable inks, it is necessary to ensure that most of the materials used in the formulation are biobased, biodegradable, or not considered critical raw materials. In this review, different inks for inkjet printing or screen printing that are considered sustainable, and the materials that can be used to formulate them, are collected. Printed electronics need inks with different functionalities, which can be mainly classified into three groups: conductive, dielectric, or piezoelectric inks. Materials need to be selected depending on the ink’s final purpose. For example, functional materials such as carbon or biobased silver should be used to secure the conductivity of an ink, a material with dielectric properties could be used to develop a dielectric ink, or materials that present piezoelectric properties could be mixed with different binders to develop a piezoelectric ink. A good combination of all the components selected must be achieved to ensure the proper features of each ink. Full article
(This article belongs to the Special Issue Advanced and Multifunctional Flexible Electronic Materials and Devices)
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61 pages, 18764 KiB  
Review
Polymer-Matrix Composites: Characterising the Impact of Environmental Factors on Their Lifetime
by Rui Barreira-Pinto, Rodrigo Carneiro, Mário Miranda and Rui Miranda Guedes
Materials 2023, 16(11), 3913; https://doi.org/10.3390/ma16113913 - 23 May 2023
Cited by 28 | Viewed by 5471
Abstract
Polymer-matrix composites are widely used in engineering applications. Yet, environmental factors impact their macroscale fatigue and creep performances significantly, owing to several mechanisms acting at the microstructure level. Herein, we analyse the effects of water uptake that are responsible for swelling and, over [...] Read more.
Polymer-matrix composites are widely used in engineering applications. Yet, environmental factors impact their macroscale fatigue and creep performances significantly, owing to several mechanisms acting at the microstructure level. Herein, we analyse the effects of water uptake that are responsible for swelling and, over time and in enough quantity, for hydrolysis. Seawater, due to a combination of high salinity and pressures, low temperature and biotic media present, also contributes to the acceleration of fatigue and creep damage. Similarly, other liquid corrosive agents penetrate into cracks induced by cyclic loading and cause dissolution of the resin and breakage of interfacial bonds. UV radiation either increases the crosslinking density or scissions chains, embrittling the surface layer of a given matrix. Temperature cycles close to the glass transition damage the fibre–matrix interface, promoting microcracking and hindering fatigue and creep performance. The microbial and enzymatic degradation of biopolymers is also studied, with the former responsible for metabolising specific matrices and changing their microstructure and/or chemical composition. The impact of these environmental factors is detailed for epoxy, vinyl ester and polyester (thermoset); polypropylene, polyamide and poly etheretherketone (thermoplastic); and for poly lactic acid, thermoplastic starch and polyhydroxyalkanoates (biopolymers). Overall, the environmental factors mentioned hamper the fatigue and creep performances, altering the mechanical properties of the composite or causing stress concentrations through microcracks, promoting earlier failure. Future studies should focus on other matrices beyond epoxy as well as on the development of standardised testing methods. Full article
(This article belongs to the Section Advanced Composites)
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38 pages, 9986 KiB  
Review
Advances in Cellulose-Based Composites for Energy Applications
by Choon Peng Teng, Ming Yan Tan, Jessica Pei Wen Toh, Qi Feng Lim, Xiaobai Wang, Daniel Ponsford, Esther Marie JieRong Lin, Warintorn Thitsartarn and Si Yin Tee
Materials 2023, 16(10), 3856; https://doi.org/10.3390/ma16103856 - 20 May 2023
Cited by 28 | Viewed by 7892
Abstract
The various forms of cellulose-based materials possess high mechanical and thermal stabilities, as well as three-dimensional open network structures with high aspect ratios capable of incorporating other materials to produce composites for a wide range of applications. Being the most prevalent natural biopolymer [...] Read more.
The various forms of cellulose-based materials possess high mechanical and thermal stabilities, as well as three-dimensional open network structures with high aspect ratios capable of incorporating other materials to produce composites for a wide range of applications. Being the most prevalent natural biopolymer on the Earth, cellulose has been used as a renewable replacement for many plastic and metal substrates, in order to diminish pollutant residues in the environment. As a result, the design and development of green technological applications of cellulose and its derivatives has become a key principle of ecological sustainability. Recently, cellulose-based mesoporous structures, flexible thin films, fibers, and three-dimensional networks have been developed for use as substrates in which conductive materials can be loaded for a wide range of energy conversion and energy conservation applications. The present article provides an overview of the recent advancements in the preparation of cellulose-based composites synthesized by combining metal/semiconductor nanoparticles, organic polymers, and metal-organic frameworks with cellulose. To begin, a brief review of cellulosic materials is given, with emphasis on their properties and processing methods. Further sections focus on the integration of cellulose-based flexible substrates or three-dimensional structures into energy conversion devices, such as photovoltaic solar cells, triboelectric generators, piezoelectric generators, thermoelectric generators, as well as sensors. The review also highlights the uses of cellulose-based composites in the separators, electrolytes, binders, and electrodes of energy conservation devices such as lithium-ion batteries. Moreover, the use of cellulose-based electrodes in water splitting for hydrogen generation is discussed. In the final section, we propose the underlying challenges and outlook for the field of cellulose-based composite materials. Full article
(This article belongs to the Special Issue Functional Cellulosic Materials)
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35 pages, 11056 KiB  
Review
Recent Advances in Magnetic Polymer Composites for BioMEMS: A Review
by Zhengwei Liao, Oualid Zoumhani and Clementine M. Boutry
Materials 2023, 16(10), 3802; https://doi.org/10.3390/ma16103802 - 17 May 2023
Cited by 22 | Viewed by 6189
Abstract
The objective of this review is to investigate the potential of functionalized magnetic polymer composites for use in electromagnetic micro-electro-mechanical systems (MEMS) for biomedical applications. The properties that make magnetic polymer composites particularly interesting for application in the biomedical field are their biocompatibility, [...] Read more.
The objective of this review is to investigate the potential of functionalized magnetic polymer composites for use in electromagnetic micro-electro-mechanical systems (MEMS) for biomedical applications. The properties that make magnetic polymer composites particularly interesting for application in the biomedical field are their biocompatibility, their adjustable mechanical, chemical, and magnetic properties, as well as their manufacturing versatility, e.g., by 3D printing or by integration in cleanroom microfabrication processes, which makes them accessible for large-scale production to reach the general public. The review first examines recent advancements in magnetic polymer composites that possess unique features such as self-healing capabilities, shape-memory, and biodegradability. This analysis includes an exploration of the materials and fabrication processes involved in the production of these composites, as well as their potential applications. Subsequently, the review focuses on electromagnetic MEMS for biomedical applications (bioMEMS), including microactuators, micropumps, miniaturized drug delivery systems, microvalves, micromixers, and sensors. The analysis encompasses an examination of the materials and manufacturing processes involved and the specific fields of application for each of these biomedical MEMS devices. Finally, the review discusses missed opportunities and possible synergies in the development of next-generation composite materials and bioMEMS sensors and actuators based on magnetic polymer composites. Full article
(This article belongs to the Special Issue Design, Fabrication, and Characterization of Magnetoresponsive Materials and Devices)
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18 pages, 4982 KiB  
Review
Varnish Formation and Removal in Lubrication Systems: A Review
by Sung-Ho Hong and Eun Kyung Jang
Materials 2023, 16(10), 3737; https://doi.org/10.3390/ma16103737 - 15 May 2023
Cited by 6 | Viewed by 4101
Abstract
This study presents the current literature regarding the investigation of varnish contamination among the various types of lubricant contaminations. As the duration of use of lubricants increases, the lubricant deteriorates and may become contaminated. Varnish has been known to cause filter plugging, sticking [...] Read more.
This study presents the current literature regarding the investigation of varnish contamination among the various types of lubricant contaminations. As the duration of use of lubricants increases, the lubricant deteriorates and may become contaminated. Varnish has been known to cause filter plugging, sticking of the hydraulic valves and fuel injection pumps, flow obstruction, clearance reduction, poor heating and cooling performance, and increased friction and wear in various lubrication systems. These problems may also result in mechanical system failures, performance degradation, and increased maintenance and repair costs. To improve the problems caused by varnish contamination, an adequate understanding of varnish is required. Therefore, in this review, the definitions and characteristics, generating machinery, generating mechanisms, causes, measurement methods, and prevention or removal methods of varnish are summarized. Most of the data presented herein are reports from manufacturers related to lubricants and machine maintenance that are included in published works. We expect that this summary will be helpful to those who are engaged in reducing or preventing varnish-related problems. Full article
(This article belongs to the Special Issue Mechanical and Tribological Properties of Advanced Materials and Coatings)
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24 pages, 4826 KiB  
Review
The Integration of Triboelectric Nanogenerators and Supercapacitors: The Key Role of Cellular Materials
by Jiajing Meng, Zequan Zhao, Xia Cao and Ning Wang
Materials 2023, 16(10), 3751; https://doi.org/10.3390/ma16103751 - 15 May 2023
Cited by 4 | Viewed by 2805
Abstract
The growing demand for sustainable and efficient energy harvesting and storage technologies has spurred interest in the integration of triboelectric nanogenerators (TENGs) with supercapacitors (SCs). This combination offers a promising solution for powering Internet of Things (IoT) devices and other low−power applications by [...] Read more.
The growing demand for sustainable and efficient energy harvesting and storage technologies has spurred interest in the integration of triboelectric nanogenerators (TENGs) with supercapacitors (SCs). This combination offers a promising solution for powering Internet of Things (IoT) devices and other low−power applications by utilizing ambient mechanical energy. Cellular materials, featuring unique structural characteristics such as high surface−to−volume ratios, mechanical compliance, and customizable properties, have emerged as essential components in this integration, enabling the improved performance and efficiency of TENG−SC systems. In this paper, we discuss the key role of cellular materials in enhancing TENG−SC systems’ performance through their influence on contact area, mechanical compliance, weight, and energy absorption. We highlight the benefits of cellular materials, including increased charge generation, optimized energy conversion efficiency, and adaptability to various mechanical sources. Furthermore, we explore the potential for lightweight, low−cost, and customizable cellular materials to expand the applicability of TENG−SC systems in wearable and portable devices. Finally, we examine the dual effect of cellular materials’ damping and energy absorption properties, emphasizing their potential to protect TENGs from damage and increase overall system efficiency. This comprehensive overview of the role of cellular materials in the integration of TENG−SC aims to provide insights into the development of next−generation sustainable energy harvesting and storage solutions for IoT and other low−power applications. Full article
(This article belongs to the Special Issue New Advances in Characterization of Cellular Materials)
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29 pages, 4902 KiB  
Review
Review of Potential Drug-Eluting Contact Lens Technologies
by Tina Lovrec-Krstič, Kristjan Orthaber, Uroš Maver and Tomislav Sarenac
Materials 2023, 16(10), 3653; https://doi.org/10.3390/ma16103653 - 11 May 2023
Cited by 7 | Viewed by 5405
Abstract
The field of ophthalmology is expanding exponentially, both in terms of diagnostic and therapeutic capabilities, as well as the worldwide increasing incidence of eye-related diseases. Due to an ageing population and climate change, the number of ophthalmic patients will continue to increase, overwhelming [...] Read more.
The field of ophthalmology is expanding exponentially, both in terms of diagnostic and therapeutic capabilities, as well as the worldwide increasing incidence of eye-related diseases. Due to an ageing population and climate change, the number of ophthalmic patients will continue to increase, overwhelming healthcare systems and likely leading to under-treatment of chronic eye diseases. Since drops are the mainstay of therapy, clinicians have long emphasised the unmet need for ocular drug delivery. Alternative methods, i.e., with better compliance, stability and longevity of drug delivery, would be preferred. Several approaches and materials are being studied and used to overcome these drawbacks. We believe that drug-loaded contact lenses are among the most promising and are a real step toward dropless ocular therapy, potentially leading to a transformation in clinical ophthalmic practice. In this review, we outline the current role of contact lenses in ocular drug delivery, focusing on materials, drug binding and preparation, concluding with a look at future developments. Full article
(This article belongs to the Special Issue Advanced Bio-Based Polymers: Synthesis, Characterization and Applications (Second Volume))
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19 pages, 8541 KiB  
Review
3D Textiles Based on Warp Knitted Fabrics: A Review
by Lars Hahn, Konrad Zierold, Anke Golla, Danny Friese and Steffen Rittner
Materials 2023, 16(10), 3680; https://doi.org/10.3390/ma16103680 - 11 May 2023
Cited by 15 | Viewed by 8197
Abstract
Fibre-reinforced composites (FRCs) are already well established in several industrial sectors such as aerospace, automotive, plant engineering, shipbuilding and construction. The technical advantages of FRCs over metallic materials are well researched and proven. The key factors for an even wider industrial application of [...] Read more.
Fibre-reinforced composites (FRCs) are already well established in several industrial sectors such as aerospace, automotive, plant engineering, shipbuilding and construction. The technical advantages of FRCs over metallic materials are well researched and proven. The key factors for an even wider industrial application of FRCs are the maximisation of resource and cost efficiency in the production and processing of the textile reinforcement materials. Due to its technology, warp knitting is the most productive and therefore cost-effective textile manufacturing process. In order to produce resource-efficient textile structures with these technologies, a high degree of prefabrication is required. This reduces costs by reducing the number of ply stacks, and by reducing the number of extra operations through final path and geometric yarn orientation of the preforms. It also reduces waste in post-processing. Furthermore, a high degree of prefabrication through functionalisation offers the potential to extend the application range of textile structures as purely mechanical reinforcements by integrating additional functions. So far, there is a gap in terms of an overview of the current state-of-the-art of relevant textile processes and products, which this work aims to fill. The focus of this work is therefore to provide an overview of warp knitted 3D structures. Full article
(This article belongs to the Collection Advanced Composite Materials and Structures for Aerospace, Automotive and Civil Engineering Applications)
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23 pages, 11793 KiB  
Review
Plasmonic Functionality of Optical Fiber Tips: Mechanisms, Fabrications, and Applications
by Bobo Du, Yunfan Xu, Lei Zhang and Yanpeng Zhang
Materials 2023, 16(9), 3596; https://doi.org/10.3390/ma16093596 - 8 May 2023
Cited by 3 | Viewed by 2601
Abstract
Optical fiber tips with the flat end-facets functionalized take the special advantages of easy fabrication, compactness, and ready-integration among the community of optical fiber devices. Combined with plasmonic structures, the fiber tips draw a significant growth of interest addressing diverse functions. This review [...] Read more.
Optical fiber tips with the flat end-facets functionalized take the special advantages of easy fabrication, compactness, and ready-integration among the community of optical fiber devices. Combined with plasmonic structures, the fiber tips draw a significant growth of interest addressing diverse functions. This review aims to present and summarize the plasmonic functionality of optical fiber tips with the current state of the art. Firstly, the mechanisms of plasmonic phenomena are introduced in order to illustrate the tip-compatible plasmonic nanostructures. Then, the strategies of plasmonic functionalities on fiber tips are analyzed and compared. Moreover, the classical applications of plasmonic fiber tips are reviewed. Finally, the challenges and prospects for future opportunities are discussed. Full article
(This article belongs to the Special Issue Advances in Multimaterial Fibers and Devices)
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18 pages, 5619 KiB  
Review
A Review of Numerical Simulation of Laser–Arc Hybrid Welding
by Zhaoyang Wang, Mengcheng Gong, Longzao Zhou and Ming Gao
Materials 2023, 16(9), 3561; https://doi.org/10.3390/ma16093561 - 6 May 2023
Cited by 18 | Viewed by 3367
Abstract
Laser–arc hybrid welding (LAHW) is known to achieve more stable processes, better mechanical properties, and greater adaptability through the synergy of a laser and an arc. Numerical simulations play a crucial role in deepening our understanding of this interaction mechanism. In this paper, [...] Read more.
Laser–arc hybrid welding (LAHW) is known to achieve more stable processes, better mechanical properties, and greater adaptability through the synergy of a laser and an arc. Numerical simulations play a crucial role in deepening our understanding of this interaction mechanism. In this paper, we review the current work on numerical simulations of LAHW, including heat source selection laws, temperature field, flow field, and stress field results. We also discuss the influence of laser–arc interaction on weld defects and mechanical properties and provide suggestions for the development of numerical simulations of LAHW. Full article
(This article belongs to the Special Issue Advances in the Experimentation and Numerical Modeling of Material Joining Processes)
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30 pages, 16400 KiB  
Review
Recent Progress for Single-Molecule Magnets Based on Rare Earth Elements
by Xiang Yin, Li Deng, Liuxia Ruan, Yanzhao Wu, Feifei Luo, Gaowu Qin, Xiaoli Han and Xianmin Zhang
Materials 2023, 16(9), 3568; https://doi.org/10.3390/ma16093568 - 6 May 2023
Cited by 13 | Viewed by 3272
Abstract
Single-molecule magnets (SMMs) have attracted much attention due to their potential applications in molecular spintronic devices. Rare earth SMMs are considered to be the most promising for application owing to their large magnetic moment and strong magnetic anisotropy. In this review, the recent [...] Read more.
Single-molecule magnets (SMMs) have attracted much attention due to their potential applications in molecular spintronic devices. Rare earth SMMs are considered to be the most promising for application owing to their large magnetic moment and strong magnetic anisotropy. In this review, the recent progress in rare earth SMMs represented by mononuclear and dinuclear complexes is highlighted, especially for the modulation of magnetic anisotropy, effective energy barrier (Ueff) and blocking temperature (TB). The terbium- and dysprosium-based SMMs have a Ueff of 1541 cm−1 and an increased TB of 80 K. They break the boiling point temperature of liquid nitrogen. The development of the preparation technology of rare earth element SMMs is also summarized in an overview. This review has important implications and insights for the design and research of Ln-SMMs. Full article
(This article belongs to the Special Issue Theory and Simulations of Magnetic Materials)
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25 pages, 63751 KiB  
Review
Copper-Based Diamond-like Thermoelectric Compounds: Looking Back and Stepping Forward
by Wenying Wang, Lin Bo, Junliang Zhu and Degang Zhao
Materials 2023, 16(9), 3512; https://doi.org/10.3390/ma16093512 - 3 May 2023
Cited by 7 | Viewed by 2800
Abstract
The research on thermoelectric (TE) materials has a long history. Holding the advantages of high elemental abundance, lead-free and easily tunable transport properties, copper-based diamond-like (CBDL) thermoelectric compounds have attracted extensive attention from the thermoelectric community. The CBDL compounds contain a large number [...] Read more.
The research on thermoelectric (TE) materials has a long history. Holding the advantages of high elemental abundance, lead-free and easily tunable transport properties, copper-based diamond-like (CBDL) thermoelectric compounds have attracted extensive attention from the thermoelectric community. The CBDL compounds contain a large number of representative candidates for thermoelectric applications, such as CuInGa2, Cu2GeSe3, Cu3SbSe4, Cu12SbSe13, etc. In this study, the structure characteristics and TE performances of typical CBDLs were briefly summarized. Several common synthesis technologies and effective strategies to improve the thermoelectric performances of CBDL compounds were introduced. In addition, the latest developments in thermoelectric devices based on CBDL compounds were discussed. Further developments and prospects for exploring high-performance copper-based diamond-like thermoelectric materials and devices were also presented at the end. Full article
(This article belongs to the Special Issue Materials Physics in Thermoelectric Materials)
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24 pages, 6212 KiB  
Review
A Review of Trends in Corrosion-Resistant Structural Steels Research—From Theoretical Simulation to Data-Driven Directions
by Di Xu, Zibo Pei, Xiaojia Yang, Qing Li, Fan Zhang, Renzheng Zhu, Xuequn Cheng and Lingwei Ma
Materials 2023, 16(9), 3396; https://doi.org/10.3390/ma16093396 - 26 Apr 2023
Cited by 9 | Viewed by 4107
Abstract
This paper provides a review of models commonly used over the years in the study of microscopic models of material corrosion mechanisms, data mining methods and the corrosion-resistant performance control of structural steels. The virtual process of material corrosion is combined with experimental [...] Read more.
This paper provides a review of models commonly used over the years in the study of microscopic models of material corrosion mechanisms, data mining methods and the corrosion-resistant performance control of structural steels. The virtual process of material corrosion is combined with experimental data to reflect the microscopic mechanism of material corrosion from a nano-scale to macro-scale, respectively. Data mining methods focus on predicting and modeling the corrosion rate and corrosion life of materials. Data-driven control of the corrosion resistance of structural steels is achieved through micro-alloying and organization structure control technology. Corrosion modeling has been used to assess the effects of alloying elements, grain size and organization purity on corrosion resistance, and to determine the contents of alloying elements. Full article
(This article belongs to the Special Issue Commemorating the Launch of the Section 'Metals and Alloys')
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23 pages, 3855 KiB  
Review
Rheology of Recycled PET
by Ilaria Cusano, Laura Campagnolo, Marco Aurilia, Salvatore Costanzo and Nino Grizzuti
Materials 2023, 16(9), 3358; https://doi.org/10.3390/ma16093358 - 25 Apr 2023
Cited by 22 | Viewed by 5491
Abstract
Polyethylene terephthalate (PET) is a thermoplastic material that is widely used in many application fields, such as packaging, construction and household products. Due to the relevant contribution of PET to global yearly solid waste, the recycling of such material has become an important [...] Read more.
Polyethylene terephthalate (PET) is a thermoplastic material that is widely used in many application fields, such as packaging, construction and household products. Due to the relevant contribution of PET to global yearly solid waste, the recycling of such material has become an important issue. Disposed PET does not maintain the mechanical properties of virgin material, as exposure to water and other substances can cause multiple chain scissions, with subsequent degradation of the viscoelastic properties. For this reason, chain extension is needed to improve the final properties of the recycled product. Chain extension is generally performed through reactive extrusion. As the latter involves structural modification and flow of PET molecules, rheology is a relevant asset for understanding the process and tailoring the mechanical properties of the final products. This paper briefly reviews relevant rheological studies associated with the recycling of polyethylene terephthalate through the reactive extrusion process. Full article
(This article belongs to the Special Issue Advanced Polymeric Materials: Synthesis, Properties, and Applications)
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30 pages, 3425 KiB  
Review
Synthesis Methods and Optical Sensing Applications of Plasmonic Metal Nanoparticles Made from Rhodium, Platinum, Gold, or Silver
by Elizaveta Demishkevich, Andrey Zyubin, Alexey Seteikin, Ilia Samusev, Inkyu Park, Chang Kwon Hwangbo, Eun Ha Choi and Geon Joon Lee
Materials 2023, 16(9), 3342; https://doi.org/10.3390/ma16093342 - 24 Apr 2023
Cited by 29 | Viewed by 5774
Abstract
The purpose of this paper is to provide an in-depth review of plasmonic metal nanoparticles made from rhodium, platinum, gold, or silver. We describe fundamental concepts, synthesis methods, and optical sensing applications of these nanoparticles. Plasmonic metal nanoparticles have received a lot of [...] Read more.
The purpose of this paper is to provide an in-depth review of plasmonic metal nanoparticles made from rhodium, platinum, gold, or silver. We describe fundamental concepts, synthesis methods, and optical sensing applications of these nanoparticles. Plasmonic metal nanoparticles have received a lot of interest due to various applications, such as optical sensors, single-molecule detection, single-cell detection, pathogen detection, environmental contaminant monitoring, cancer diagnostics, biomedicine, and food and health safety monitoring. They provide a promising platform for highly sensitive detection of various analytes. Due to strongly localized optical fields in the hot-spot region near metal nanoparticles, they have the potential for plasmon-enhanced optical sensing applications, including metal-enhanced fluorescence (MEF), surface-enhanced Raman scattering (SERS), and biomedical imaging. We explain the plasmonic enhancement through electromagnetic theory and confirm it with finite-difference time-domain numerical simulations. Moreover, we examine how the localized surface plasmon resonance effects of gold and silver nanoparticles have been utilized for the detection and biosensing of various analytes. Specifically, we discuss the syntheses and applications of rhodium and platinum nanoparticles for the UV plasmonics such as UV-MEF and UV-SERS. Finally, we provide an overview of chemical, physical, and green methods for synthesizing these nanoparticles. We hope that this paper will promote further interest in the optical sensing applications of plasmonic metal nanoparticles in the UV and visible ranges. Full article
(This article belongs to the Special Issue Advances in Metal-Based Nanoparticles)
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34 pages, 2112 KiB  
Review
Nanotechnology Applied to Cellulosic Materials
by Ana Fernandes, Luísa Cruz-Lopes, Bruno Esteves and Dmitry Evtuguin
Materials 2023, 16(8), 3104; https://doi.org/10.3390/ma16083104 - 14 Apr 2023
Cited by 31 | Viewed by 6955
Abstract
In recent years, nanocellulosic materials have attracted special attention because of their performance in different advanced applications, biodegradability, availability, and biocompatibility. Nanocellulosic materials can assume three distinct morphologies, including cellulose nanocrystals (CNC), cellulose nanofibers (CNF), and bacterial cellulose (BC). This review consists of [...] Read more.
In recent years, nanocellulosic materials have attracted special attention because of their performance in different advanced applications, biodegradability, availability, and biocompatibility. Nanocellulosic materials can assume three distinct morphologies, including cellulose nanocrystals (CNC), cellulose nanofibers (CNF), and bacterial cellulose (BC). This review consists of two main parts related to obtaining and applying nanocelluloses in advanced materials. In the first part, the mechanical, chemical, and enzymatic treatments necessary for the production of nanocelluloses are discussed. Among chemical pretreatments, the most common approaches are described, such as acid- and alkali-catalyzed organosolvation, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, ammonium persulfate (APS) and sodium persulfate (SPS) oxidative treatments, ozone, extraction with ionic liquids, and acid hydrolysis. As for mechanical/physical treatments, methods reviewed include refining, high-pressure homogenization, microfluidization, grinding, cryogenic crushing, steam blasting, ultrasound, extrusion, aqueous counter collision, and electrospinning. The application of nanocellulose focused, in particular, on triboelectric nanogenerators (TENGs) with CNC, CNF, and BC. With the development of TENGs, an unparalleled revolution is expected; there will be self-powered sensors, wearable and implantable electronic components, and a series of other innovative applications. In the future new era of TENGs, nanocellulose will certainly be a promising material in their constitution. Full article
(This article belongs to the Special Issue Application of Natural Polymers in Bio-Based Products)
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42 pages, 21104 KiB  
Review
Principles and Applications of Resonance Energy Transfer Involving Noble Metallic Nanoparticles
by Zhicong He, Fang Li, Pei Zuo and Hong Tian
Materials 2023, 16(8), 3083; https://doi.org/10.3390/ma16083083 - 13 Apr 2023
Cited by 14 | Viewed by 3490
Abstract
Over the past several years, resonance energy transfer involving noble metallic nanoparticles has received considerable attention. The aim of this review is to cover advances in resonance energy transfer, widely exploited in biological structures and dynamics. Due to the presence of surface plasmons, [...] Read more.
Over the past several years, resonance energy transfer involving noble metallic nanoparticles has received considerable attention. The aim of this review is to cover advances in resonance energy transfer, widely exploited in biological structures and dynamics. Due to the presence of surface plasmons, strong surface plasmon resonance absorption and local electric field enhancement are generated near noble metallic nanoparticles, and the resulting energy transfer shows potential applications in microlasers, quantum information storage devices and micro-/nanoprocessing. In this review, we present the basic principle of the characteristics of noble metallic nanoparticles, as well as the representative progress in resonance energy transfer involving noble metallic nanoparticles, such as fluorescence resonance energy transfer, nanometal surface energy transfer, plasmon-induced resonance energy transfer, metal-enhanced fluorescence, surface-enhanced Raman scattering and cascade energy transfer. We end this review with an outlook on the development and applications of the transfer process. This will offer theoretical guidance for further optical methods in distance distribution analysis and microscopic detection. Full article
(This article belongs to the Special Issue Fundamentals and Applications of Laser Micro/Nanostructuring and Synthesis of Micro/Nanomaterials)
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21 pages, 2579 KiB  
Review
Thermal Conductivity of Aluminum Alloys—A Review
by Ailing Zhang and Yanxiang Li
Materials 2023, 16(8), 2972; https://doi.org/10.3390/ma16082972 - 8 Apr 2023
Cited by 99 | Viewed by 17658
Abstract
Aluminum alloys have been extensively used as heatproof and heat-dissipation components in automotive and communication industries, and the demand for aluminum alloys with higher thermal conductivity is increasing. Therefore, this review focuses on the thermal conductivity of aluminum alloys. First, we formulate the [...] Read more.
Aluminum alloys have been extensively used as heatproof and heat-dissipation components in automotive and communication industries, and the demand for aluminum alloys with higher thermal conductivity is increasing. Therefore, this review focuses on the thermal conductivity of aluminum alloys. First, we formulate the theory of thermal conduction of metals and effective medium theory, and then analyze the effect of alloying elements, secondary phases, and temperature on the thermal conductivity of aluminum alloys. Alloying elements are the most crucial factor, whose species, existing states, and mutual interactions significantly affect the thermal conductivity of aluminum. Alloying elements in a solid solution weaken the thermal conductivity of aluminum more dramatically than those in the precipitated state. The characteristics and morphology of secondary phases also affect thermal conductivity. Temperature also affects thermal conductivity by influencing the thermal conduction of electrons and phonons in aluminum alloys. Furthermore, recent studies on the effects of casting, heat treatment, and AM processes on the thermal conductivity of aluminum alloys are summarized, in which processes mainly affect thermal conductivity by varying existing states of alloying elements and the morphology of secondary phases. These analyses and summaries will further promote the industrial design and development of aluminum alloys with high thermal conductivity. Full article
(This article belongs to the Special Issue Structure and Mechanical Properties of Alloys, Volume II)
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