Showing papers in "Frontiers in Materials in 2021"
TL;DR: The direct material deposition characteristic of the DIW process enables it to print on a variety of flat substrates, even a conformal one, well suiting them to applications such as wearable devices and on-chip integrations as discussed by the authors.
Abstract: Recently, the fabrication of electronics-related components via DIW has attracted much attention. Compared to the conventionally fabricated electronic components, DIW-printed ones have more complicated structures, higher accuracy, improved efficiency, and even enhanced performances that arise from well-designed architectures. The direct material deposition characteristic of the DIW process enables it to print on a variety of flat substrates, even a conformal one, well suiting them to applications such as wearable devices and on-chip integrations. Here, recent developments in DIW printing of emerging components for electronics-related applications are briefly reviewed, including electrodes, electronic circuits, and functional components. The printing techniques, processes, ink materials, advantages, and properties of DIW-printed architectures are discussed. Finally, the challenges and outlooks on the manufacture of 3D structured electronic devices by DIW are outlined, pointing out future designs and developments of DIW technology for electronics-related applications. The combination of DIW and electronic devices will help to improve the quality of human life and promote the development of science and society.
44 citations
TL;DR: In this paper, three artificial intelligence (AI) techniques namely; artificial neural network (ANN), adaptive neuro-fuzzy interface (ANFIS), and gene expression programming (GEP) are used to establish a reliable and accurate model to estimate the compressive strength (f_c^') of fly-ash based geopolymer concrete (FGPC).
Abstract: The ultrafine fly-ash (FA) is a hazardous material collected from coal productions, which has been proficiently employed for the manufacturing of geo-polymer concrete (GPC). In this paper, the three artificial intelligence (AI) techniques namely; artificial neural network (ANN), adaptive neuro-fuzzy interface (ANFIS), and gene expression programming (GEP) are used to establish a reliable and accurate model to estimate the compressive strength (f_c^') of fly-ash based geopolymer concrete (FGPC). A database of 298 instances is developed from the peer-reviewed published work. The database consists of the ten most prominent explanatory variables and f_c^' of FGPC as a response parameter. The statistical error checks and criteria suggested in the literature are considered for the verification of the predictive strength of the models. The statistical measures considered in this study are MAE, RSE, RMSE, RRMSE, R, and performance index (ρ). These checks verify that ANFIS predictive model gives an outstanding performance followed by GEP and ANN predictive models. In the validation stage, the coefficient of correlation (R) for ANFIS, GEP, and ANN model is 0.9783, 0.9643, and 0.9314 respectively. All three models also fulfill the external verification criterion suggested in the literature. Generally, GEP predictive model is ideal as it delivers a simplistic and easy mathematical equation for future use. The k-fold cross-validation (CV) of the GEP model is also conducted, which verifies the robustness of the GEP predictive model. Furthermore, the parametric study is carried via proposed GEP expression. This confirms that the GEP model accurately covers the influence of all the explanatory variables used for the prediction of f_c^' of FGPC. Thus, the proposed GEP equation can be used in the preliminary design of FGPC.
44 citations
TL;DR: Carbon quantum dots (CQDs) are a new type of nanocarbons that are currently favored over semiconductor quantum dots because of their solubility, low toxicity, eco-friendly, cheap and facile synthesis giving desired optical characteristics as discussed by the authors.
Abstract: Carbon quantum dots (CQDs) are a new type of nanocarbons that are currently favored over semiconductor quantum dots (QDs) because of their solubility, low toxicity, eco-friendly, cheap and facile synthesis giving desired optical characteristics. Moreover, their physiochemical properties can be controlled by its synthetic route. CQDs can emit fluorescence in the range from UV to near infrared (NIR) region making it suitable for biomedical applications. Fluorescence in these nanocarbons can be tuned by varying the excitation wavelength. As of now, CQDs have been used in various applications such as bioimaging, biosensing and drug-delivery. This article highlights the current progress and advancement of CQDs with focus on their chemical and optical properties, their synthetic routes and biomedical applications along with new perceptions in this interesting and promising field.
42 citations
TL;DR: In this paper, a comprehensive introduction of the Si, SiGe nanowires and their possibility for micro-thermoelectric generators (μTEG) is given. But, the authors do not discuss their applications.
Abstract: In our environment, large availability of wasted heat has been driven to search for methods to harvest heat for many years. As a reliable way for the energy supply, SiGe has been used for thermoelectric generators in space missions for decades. Recently, micro-thermoelectric generators (μTEG) turn out to be a promising way to supply energy for internet of things (IoT) by using daily waste heat. Combining the predominant CMOS compatibility with high electric conductivity and low thermal conductivity performance, Si nanowire and SiGe nanowire have been a candidate for μTEG. This review gives a comprehensive introduction of the Si, SiGe nanowires and their possibility for μTEG. The basic thermoelectric principles, materials, structures, fabrication, measurements and applications are discussed deep inside.
39 citations
TL;DR: In this article, the authors summarized the latest methods and materials used to construct stable biosensor interfaces, and pointed some future perspectives and challenges of them, and found that nanomaterials, polymers as well as their composites such as chitosan, cellulose and conducting polymers are the most common materials used in the biosensor interface design.
Abstract: Biosensor can convert the concentration of biological analyte into an electrical signal or other signals for detection. It is widely used in medical diagnostics, food safety, process control and environmental monitoring fields. In recent years, new schemes of stable biosensor interfaces have attracted much attention. Interface design is a vital part of biosensor development, since its stability can be directly related to the quality of sensing performance such as sensitivity, stability and linearity. This review summarized the latest methods and materials used to construct stable biosensor interfaces, and pointed some future perspectives and challenges of them. From the literature, we found that nanomaterials, polymers as well as their composites such as chitosan, cellulose and conducting polymers are the most common materials used in the biosensor interfaces design. Apart from materials, there are increasing developments in monolayer membranes techniques, three-dimensional constructions and other interface techniques. This review is a study of the latest progress in biosensor interface stability solutions, which may provide some references and innovative directions of biosensor interface design for researchers in biosensor fields, and encourage people to further explore new materials and methods.
36 citations
TL;DR: In this paper, the influence of various doses of Rice Husk Ash (RHA) used in concrete in the presence and absence of steel fibers and concrete performance has been examined.
Abstract: The production of rice is significant worldwide; the husk produced is generally used as a combustible material for the preparation of paddies, delivering energy through direct combustion as well as by gasifying. Annually, 7.4 million tons of Rice Husk Ash (RHA) is produced and poses an incredible danger to the environment, harming the land and the encompassing zone where it is unloaded. In the transformation of rice husk to ash, the ignition cycle eliminates the natural products, leaving silica-rich remains. These silica-rich remains have proven to have potential to be utilized in concrete as a limited substitution of cement to enhance the concrete compressive strength. Steel fibers' incorporation increases the concrete tensile strength, balances out concrete samples, and changes their brittle behavior to a more ductile response. In the current study, the influence of various doses of Rice Husk Ash (RHA) used in concrete in the presence and absence of steel fibers and concrete performance has been examined. A total of nine mixes have been designed: one was a control, four were without steel fibers containing only RHA, and the last four mixed RHA with steel fibers from 0.5 to 2%. Tests with 5, 10, 15, and 20% percentages of RHA replacing the concrete have been targeted. Results have been compared with the reference samples and the reasonability of adding Rice Husk Ash to concrete has been studied. From the results, it was noted that about 10% of cement might be replaced with Rice Husk Ash mixed in with steel fibers with almost equal compressive strength. Replacing more than 15% of cement with RHA will produce concrete with a low performance in terms of strength and durability.
35 citations
TL;DR: In this paper, the state-of-the-art MR fluid-based devices are reviewed according to structural configurations reported from 2018 to 2020, and an overview of the significant issues occurred in MR fluidbased devices is reported, and the developing trends are discussed for the devices with MR fluid.
Abstract: Magnetorheological (MR) fluid is a kind of smart materials with rheological behavior change by means of external magnetic field application, which has been widely adopted in many complex systems of different technical fields. In this work, the state-of-the-art MR fluid-based devices are reviewed according to structural configurations reported from 2018 to 2020. Based on the rheological characteristic, MR fluid has a variety of operational modes, such as flow mode, shear mode, squeeze mode and pinch mode, and plays unique advantages in some special practical applications. Thus, referring to these operational modes, improved engineering mechanical devices with MR fluid are summarized including brakes, clutch, damper and mount proposed over the last three years. Furthermore, some new medical devices used MR fluid are also investigated, for instance, surgical assistive devices and artificial limb. In particular, some outstanding advances on structural innovations and application superiority of these devices are introduced in detail. Finally, an overview of the significant issues occurred in the MR fluid-based devices is reported, and the developing trends are discussed for the devices with MR fluid.
33 citations
TL;DR: In this article, a review of the recent electrochemical detection of heavy metal ions, pesticides and emerging pollutants based on hybridized graphene is presented, where current challenges related to graphene applicability, envisaged opportunities and future perspectives are outlined.
Abstract: Population-driven socioeconomic urban expansion, industrialization and intensified modern agricultural practices are interlinked to environmental challenges which induce harmful repercussions on the health of human beings. Consequently, these challenges have culminated in compromised water quality due to pollution by toxic, persistent and bioaccumulative heavy metal ions, pesticides, and emerging pollutants. Most pollutants cause severe health dilemma including impairment of vital body organs like lungs, liver, kidneys, reproductive and nervous systems. Besides, some organic contaminants interfere with natural enzyme and hormonal functioning such as the endocrine system. Considering the detrimental impact of pollutants, their detection in different media including water is paramount. Notably, electrochemical techniques are more appealing owing to their facileness, sensitivity, portability, the potential for being used instantaneously, in situ and onsite comparative to conventional methods. Electrochemical sensing utilizing graphene derived nanocomposites have become attractive based on mechanical strength, electric conduction, and huge surface area to volume ratio of graphene. Apart from that, graphene-based materials are functionalisable owing to the prevalence of oxygen-rich entities. Thus, they are amenable for the incorporation of different components for modifying electrodes. Ultimately, combinational synergistic aftermaths in electrochemical sensor behaviour are being realized following functionalization and electrode modification with nanocomposites. This review summarizes graphene and its derivatives synthesis pathways. Besides that, the review describes the functionalization of graphene derived materials exploiting properties of metal (oxides) nanoparticles, conducting polymers, organic or inorganic materials, and other carbon materials like carbon nanotubes. Furthermore, the review evaluates the recent electrochemical detection of heavy metal ions, pesticides and emerging pollutants founded on hybridized graphene. For natural organic matter, the absence of reports on their sensing based on functionalized graphene derivatives is highlighted. In reckoning, current challenges related to graphene applicability, envisaged opportunities and future perspectives are outlined.
25 citations
TL;DR: A review of mycelium-based bio-composites materials can be found in this paper, where it is shown that the material function of these composites can be further tuned by controlling the species of fungus, the growing conditions, and the post-growth processing method to meet a specific mechanical requirement in applications.
Abstract: Mycelium-based bio-composites materials have been invented and widely applied to different areas including the construction industry, manufacturing industry, agriculture, and biomedical. As the vegetative part of a fungus, mycelium has the unique capability to utilize agricultural crop waste (e.g., sugarcane bagasse, rice husks, cotton stalks, straw and stover) as substrates for the growth of its network, which integrates the wastes from pieces to continuous composites without energy input nor generating extra waste. Their low-cost and environmentally friendly features attract interest in its research and commercialization. For example, mycelium-based foam and sandwich composites have been actively developed for construction structures. It can be used as synthetic planar materials (e.g., plastic films and sheets), larger low-density objects (e.g., synthetic foams and plastics), and semi-structural materials (e.g., paneling, flooring, furniture, decking). It is shown that the material function of these composites can be further tuned by controlling the species of fungus, the growing conditions, and the post-growth processing method to meet a specific mechanical requirement in applications (e.g., structural support, acoustic and thermal insulation). Moreover, mycelium can be used to produce chitin and chitosan, which have been applied to clinical trials for wound healing, showing the potential for biomedical applications. Given the strong potential and multiple advantages of such a material, we are interested in studying them in-depth and review the current progress of their related study in this review paper.
25 citations
TL;DR: In this paper, the physical and chemical properties of multilayer transparent wood have been investigated and compared with that of single layer transparent wood with the same thickness in terms of light transmittance and tensile strength.
Abstract: In this paper, poplar was used as raw material, sodium chlorite was used to delignify it in acidic environment, and then epoxy resin was vacuum impregnated in the delignified wood template to prepare transparent wood. Moreover, in order to imitate the lamination method of plywood, the multilayer transparent wood was prepared by means of staggered vertical lamination, which greatly improved the thickness of transparent wood. The purpose of this paper is to study the physical and chemical properties of multilayer transparent wood, and to explore the application potential of multilayer transparent wood as a new material by comparing with single layer transparent wood with the same thickness. Scanning electron microscopy (SEM) measurements, Fourier transform attenuated total reflection infrared spectroscopy (ATR-FTIR) characterization, weight gain measurements, UV transmittance measurements, color difference measurements, water contact angle measurements and mechanical properties measurements were used to study. The results show that the transmittance and mechanical properties of multilayer transparent wood are better than that of single layer transparent wood with the same thickness. The specific performance is that the same thickness of transparent wood due to its different fiber direction would produce a certain difference in light transmittance. The transmittance of transparent wood with different thickness decreased with the increase of thickness. The light transmittance of multilayer transparent wood is higher than that of single layer transparent wood with the same thickness. Moreover, compared with the single layer transparent wood with the same thickness, the lightness of the multilayer transparent wood decreased, and tended to be yellow and red. The tensile strength of transparent wood decreased due to the removal of lignin in the preparation process. However, the tensile strength of multilayer transparent wood is much higher than that of single layer transparent wood, which can improve this defect to some extent. Multilayer transparent wood can solve the problem of small thickness of single layer transparent wood to a certain extent. It is a kind of natural transparent material with large thickness, good transmittance and excellent mechanical properties, and has a good development prospect.
22 citations
TL;DR: In this paper, the authors focus on the parameters and the factors which may help decrease the difficulties of ultrasonic welding of Aluminum MMC, alongside reviewing the current technologies and research works.
Abstract: The Aluminum metal matrix with particulate reinforcements is the new future of the coming industrial revolution due to the higher strength and also due to its availability. The composite reinforcements like SiC, TiB2, B4C, etc., are the major contributor to the increased strength of the Aluminum metal matrix, which can be an optimal choice, also with lower costs other than those scarce/rare metals with high strength with low life in some applications where Aluminum is into consideration or proven to withstand. Ultrasonic welding is the process, where, we get the electrical energy, which is converts and amplifies into vibration energy for the welding to occur. The challenge we face today is the thickness limitations in ultrasonic welding. The ultrasonic welding of the Aluminum metal sheet with the reinforcements may affect it, as the addition of particulate reinforcements will increase the strength of the Aluminum matrix. The ultrasonic welding only supports a metal sheet with thickness up to 2.5 mm in the case of an Aluminum plain sheet, and if the strength increases in the same Aluminum metal matrix, then the next step to proceed with it to achieve ultrasonic welding with the same thickness of Aluminum matrix along with the reinforced composites, which has more strength than that of a standard Aluminum sheet. This review will focus on the parameters and the factors which may help decrease the difficulties of Ultrasonic Welding of Aluminum MMC, alongside reviewing the current technologies and research works.
TL;DR: A review of current research activities on growth of ZnO nanorods is presented in this paper, where various water based routes of synthesis, and is further characterized by the type of substrate used for the growth.
Abstract: Nanostructured ZnO has got a lot of interest as a suitable material for various applications especially sensing, energy conversion and storage. ZnO nanostructures can be synthesized in a number of ways. It is one of the materials that can be prepared in a variety of morphologies including hierarchical nanostructures. This review article presents a review of current research activities on growth of ZnO Nanorods. The article covers various water based routes of synthesis, and is further characterized by the type of substrate used for the growth. The growth factors involved in the hydrothermal and chemical bath deposition methods are discussed. These factors include the variety of precursors, time, temperature and the seeding method employed. At the end, applications such as gas sensing and improvement in opto-electric properties in relation to the morphology are discussed.
TL;DR: The use of carbon-based materials as catalyst supports for Fischer-Tropsch synthesis (FTS) is thoroughly reviewed in this article, where the main factors to consider when using a carbonaceous catalyst support for FTS are first discussed and then, the most relevant and recent literature on the topic from the last two decades is reviewed, classifying the different examples according to the carbon structure and shape.
Abstract: The use of carbon-based materials as catalyst supports for Fischer-Tropsch synthesis (FTS) is thoroughly reviewed The main factors to consider when using a carbonaceous catalyst support for FTS are first discussed Then, the most relevant and recent literature on the topic from the last two decades is reviewed, classifying the different examples according to the carbon structure and shape Some aspects such as the carbon textural properties, carbon support modification (functionalization and doping), catalyst preparation methods, metal particle size and location, catalyst stability and reducibility, the use of promoters and the catalyst performance for FTS are summarized and discussed Finally, the main conclusions, advantages, limitations and perspectives of using carbon catalyst supports for FTS are outlined
TL;DR: A broad survey of the synthesis of multifunctional mesoporous silica nanoparticles (MSNs) based nanostructures with exotic shapes and sizes is provided in this article.
Abstract: Porous nano-scaffolds provide for better opportunities to restore, maintain, and improve functions of damaged tissues and organs by facilitating tissue regeneration. Various nanohybrids composed of mesoporous silica nanoparticles (MSNs) are being widely explored for tissue engineering. Since biological activity is enhanced by several orders of magnitude in multicomponent scaffolds, remarkable progress has been observed in this field, which has aimed to develop controlled synthesis of multifunctional MSNs with tuneable pore size, efficient delivering capacity of bioactive factors, as well as enhanced biocompatibility and biodegradability. In this review, we aim to provide a broad survey of the synthesis of multifunctional MSN based nanostructures with exotic shapes and sizes. Further, their promise as a novel nanomedicine is also elaborated with respect to their role in bone tissue engineering. Also, recent progress in surface modification and functionalization with various polymers like poly(L-lactic acid)/poly(e-caprolactone), polylysine-modified polyethylenimine, poly(lactic-co-glycolic acid), and poly(citrate-siloxane) and biological polymers like alginate, chitosan, gelatin are also covered. Several attempts for conjugating drugs like dexamethasone and β–estradiol, antibiotics like vancomycin and levofloxacin, and imaging agents like fluorescein isothiocyanate and gadolinium, on the surface modified MSNs are also covered. Finally, the scope of developing orthopaedic implants and potential trends in 3D bioprinting applications of MSNs are also discussed. Hence, MSNs based nanomaterials may serve as improved candidate biotemplates or scaffolds for numerous bone tissue engineering, drug delivery and imaging applications deserving our full attention now.
TL;DR: In this article, an enhanced dry process of mixing procedure was proposed and evaluated based on the analysis, and the results showed that the addition of plastic particles using the conventional dry process contributed a significant effect on the aggregate gradation of the produced mixture when a high plastic content was used.
Abstract: In recent years, the proliferation of plastic waste has become a global problem. A potential option to this problem is the dry process, which incorporates plastic waste into asphalt mixtures. However, the dry process often has inconsistent performance because of the improper distribution of plastic waste particles in the mixture skeleton. This inconsistency may be caused by a wrong mixing method, shredding size, mixing temperature and ingredient priorities. Thus, this study aims to improve the consistency of the dry process by comparing the control asphalt mixture and two plastic waste-modified asphalt mixtures prepared using the dry process. Quantitative sieving analysis and performance tests were carried out to examine the effects of plastic waste added into the asphalt mixture. The volumetric and performance properties combined with image analysis of the modified mixtures were obtained and compared with the control mixture. In addition, the moisture damage, resilient modulus, creep deformation and rutting were evaluated. This study also highlighted in detail the distribution of plastic particles in the final skeleton of the asphalt mixture. Based on the analysis, an enhanced dry process of mixing procedure was proposed and evaluated. Results showed that the addition of plastic particles using the conventional dry process contributed a significant effect on the aggregate gradation of the produced mixture when a high plastic content was used. Furthermore, the enhanced dry process developed in this study presents substantial enhancement in the asphalt performance, particularly with plastic waste that accounts for 20% of the weight of the asphalt binder.
TL;DR: In this paper, the authors present a comprehensive study on the recent research progress on the application of nanomaterials for electromagnetic shielding and absorption and cover microwave absorption mechanism and absorption performance using graphene, MXenes, carbon nanotubes (CNTs), carbides, and ferromagnetic metals.
Abstract: Rapid advancements and wide spread of microwave- and RF-communication systems over the years, have led to an abundant increase in electromagnetic energy radiation in our living environment Such increase in microwave sources is due to the development and advancement in communication techniques (mobile phones, laptops, antennas for aeronautics or automobile) and electronic warfare in the military field (radar, Satellite) Recently research efforts are focused on finding solutions to guarantee protection from electromagnetic (EM) radiations The EM absorbing materials are used to overcome these issues to ensure public protection as well as safe military operations Various types of EM absorbing materials comprising of composite materials have been progressively developed and researched This kind of materials is developed by impeding absorbing charges (magnetic or dielectric) into a host matrix material Recently, carbon allotropes such as graphene, MXenes, carbon nanotubes (CNTs) and carbon fiber have attracted increasing attention owing to their EMI shielding characteristics and lightweight This work presents a comprehensive study on the recent research progress on the application of nanomaterials for electromagnetic shielding and absorption The review will cover microwave absorption mechanism and absorption performance using graphene, MXenes, carbon nanotubes (CNTs), carbides, and ferromagnetic metals Overall, the review will present a timely update on the research progress of microwave absorption performance of various nanomaterials
TL;DR: In this paper, the authors present recent advances in the design and nanostructuring of TiO2-containing antireflective self-cleaning coatings for solar cells.
Abstract: Titanium(IV) oxide (TiO2, titania) is well-known for its excellent photocatalytic properties, wide bandgap, chemical resistance, and photostability. Nanostructured TiO2 is extensively utilized in various electronic and energy-related applications such as resistive switching memory devices, flat panel displays, photodiodes, solar water-splitting, photocatalysis, and solar cells. This article presents recent advances in the design and nanostructuring of TiO2-containing antireflective self-cleaning coatings for solar cells. In particular, the energy harvesting efficiency of a solar cell is greatly diminished by the surface reflections and deposition of environmental contaminants over time. Nanostructured TiO2 coatings not only minimize reflection through the graded transition of the refractive index but simultaneously improve the device’s ability to self-clean and photocatalytically degrade the pollutants. Thus, novel approaches to achieve higher solar cell efficiency and stability with pristine TiO2 and TiO2-containing nanocomposite coatings are highlighted herein. The results are compared and discussed to emphasize the key research and development shortfalls and a commercialization perspective is considered to guide future research.
TL;DR: An overview of recent developments in biomimetic 3D printing materials with enhanced mechanical properties is provided in this paper, where the design and fabrication inspired are from various creatures, such as lobster claw, honeycomb, nacre, balsa wood, etc.
Abstract: Nature has developed a wide range of functional microstructures with optimized mechanical properties over millions of years of evolution. Biomimicry, by learning from nature’s excellent models and principles, is providing a practicable strategy for designing and fabricating the next smart materials with enhanced properties. Nevertheless, the complicated micro-structural architectures in nature models exceed the capability of traditional processes, hindering the developments of biomimetic research and its forthputting in engineering systems. Additive manufacturing (AM) or 3D printing process has revolutionized the manufacturing world through its freedom of design, mass customization, waste minimization, and ability to manufacture complex micro/mesostructures, as well as fast prototyping. Here, an overview of recent developments in biomimetic 3D printing materials with Enhanced mechanical properties is provided. The design and fabrication inspired are from various creatures, such as lobster claw, honeycomb, nacre, balsa wood, etc., are present and discussed. Finally, future challenges and perspectives are given.
TL;DR: In this paper, an AC magnetic field of 3mT amplitude was produced over a range of 400 kHz to 1.1 MHz and applied to a dilute aqueous ferrofluid solution composed of ferrous magnetic nanoparticles.
Abstract: In the current work, the hypothesis that the hyperthermia power of magnetic nanoparticles is proportional to the frequency of the applied AC, is tested. To examine the validity of this hypothesis, an AC magnetic field of 3mT amplitude was produced over a range of 400 kHz to 1.1 MHz and applied to a dilute aqueous ferrofluid solution composed of ferrous magnetic nanoparticles. It is a common belief in the literature that the hyperthermia power is an increasing function of frequency but there were not anywhere a systematic study prior to our work to prove this hypothesis. In the current work such a systematic study takes place and indeed it reveals a direct relationship between the two physical quantities. In particular, the SAR parameter which is the ratio of the heat power in Watts produced per nanoparticle mass in grams, is linear to a good degree to the frequency with a step of roughly 30 W/g per a 100 kHz increase. Our SAR values were in the 100 to 300 W/g range which is within the range of values reported elsewhere. Additionally, our measured data of temperature versus time at each frequency, were explained in terms of simple thermodynamic arguments, in order to extract useful thermodynamic parameters for the magnetic nanoparticles, in particular the heat power that they produce.
TL;DR: In this article, the authors studied the mechanical performance of sustainable concrete incorporating waste materials as aggregates, the study is performed in the three stages, in the 1st stage, the natural sand was substituted with recycled sand in the percentage of 0, 35, 70, and 100%, and all the tests i.e. compressive strength, split tensile strength and flexural strength were performed on concrete which was cured in water for 28 days.
Abstract: With the development of technology in every field, it is necessary to recommend an eco-friendly material to be utilized in the construction industry. Recently, using waste/recycled materials in the concrete as a substitute is a trend to bring sustainability to the construction industry, but the recycled/waste materials has poor mechanical properties, thus to enhance these poor properties, this research studies the mechanical performance of sustainable concrete incorporating waste materials as aggregates, the study is performed in the three stages. In the 1st stage, the natural sand was substituted with recycled sand in the percentage of 0, 35, 70, and 100%, and all the tests i.e. compressive strength, split tensile strength and flexural strength were performed on concrete which was cured in water for 28 days. As the 35% substitution of natural sand with recycled fine aggregate presented the optimum mechanical performance, it was selected for the 3rd stage of the research. In the 2nd and the 3rd stages, the discarded carbon fibers were utilized in concrete with 2%, 4%, and 6% by weight. A total of 90 samples were prepared for this research, in which 30 samples were cubes, 30 samples were cylinders and 30 samples were beams, all the samples were tested at 28 days. Comparative analysis was performed to validate and verify the results of this paper with the relevant literature. The SEM test was also performed on a fractured concrete surface to study its microstructure. The outcome of tests revealed that the utilization of discarded carbon fibers in concrete enhances compressive, split tensile and flexural strength by 27.8%, 17.8%, and 35.9% and acts as a crack bridging and also restrain the propagation of the first cracks. Fibers also helped the concrete to improve its energy absorption capacity and ductility.
TL;DR: In this paper, 45S5 bioactive glass-based scaffolds were coated with corn protein zein and Manuka honey with two purposes: to improve the mechanical properties of the brittle scaffolds and to impart antibacterial properties.
Abstract: The combination of traditional herbal medicine (phytotherapeutic agents) with bioactive glasses is a promising strategy to generate advanced scaffolds for bone tissue engineering (BTE). An old remedy used for wound care since ancient times is honey. The antioxidant, antimicrobial and antibacterial properties of Manuka honey, in particular, make it an attractive substance for application in BTE scaffolds to prevent infections and biofilm formation. In this study 45S5 bioactive glass-based scaffolds produced via the foam replica technique were coated with corn protein zein and Manuka honey with two purposes: to improve the mechanical properties of the brittle scaffolds and to impart antibacterial properties. The morphology and chemical composition of the coated scaffolds were characterized with scanning electron microscopy and Fourier transform infrared spectroscopy, respectively, demonstrating the presence of Manuka honey in the coating. The release of the honey was quantified via ultraviolet-visible spectrophotometry; moreover, the antibacterial activity against Staphylococcus aureus was evaluated via colony-forming units counting, reduction of Alamar blue and turbidity measurements. Our findings suggest the effective combination of Manuka honey and bioactive glass, adding one more system to the novel family of bioactive glass scaffolds functionalized with phytotherapeutic agents.
TL;DR: In this article, a review of elastin-like recombinamer-based porous biomaterials for both soft and hard tissue applications is discussed, and their current and future applications evaluated.
Abstract: Porous biomaterials are of significant interest in a variety of biomedical applications as they enable the diffusion of nutrients and gases as well as the removal of metabolic waste from the implants. Pores also provide 3D spaces for cell compartmentalisation and the development of complex structures such as vasculature and the extracellular matrix. Given the variation in the extracellular matrix composition across and within different tissues, it is necessary to tailor the physicochemical characteristics of biomaterials and or surfaces thereof for optimal bespoke applications. In this regard, different synthetic and natural polymers have seen increased usage in the development of biomaterials and surface coatings, among them, elastin-like polypeptides and their recombinant derivatives have received increased advocacy. The modular assembly of these molecules, which can be controlled at a molecular level, presents a flexible platform for the endowment of bespoke biomaterials properties. In this review, various elastin-like recombinamer based porous biomaterials for both soft and hard tissue applications are discussed, and their current and future applications evaluated.
TL;DR: This work presents a machine learning based framework in which the point defect energies in MPEAs are predicted from a database of their constituent binary alloys, and demonstrates predictions of vacancy migration and formation energies in Ni-Fe-Cr-Co-Cu system.
Abstract: Multi-principal element alloys (MPEAs) are a new class of alloys that consist of many principal elements randomly distributed on a crystal lattice. The random presence of many elements lends large variations in the point defect formation and migration energies even within a given alloy composition. Compounded by the fact that there could be exponentially large number of MPEA compositions, there is a major computational challenge to capture complete point-defect energy phase-space in MPEAs. In this work, we present a machine learning based framework in which the point defect energies in MPEAs are predicted from a database of their constituent binary alloys. We demonstrate predictions of vacancy migration and formation energies in face centered cubic ternary, quaternary and quinary alloys in Ni-Fe-Cr-Co-Cu system. A key benefit of building this framework based on the database of binary alloys is that it enables defect-energy predictions in alloy compositions that may be unearthed in future. Furthermore, the methodology enables identifying the impact of a given alloying element on the defect energies thereby enabling design of alloys with tailored defect properties.
TL;DR: In this paper, the purpose of polymer blending in drug delivery systems has been discussed and the consequence of each blending method on drug release profile and kinetics of drug release have been discussed.
Abstract: Different polymeric materials have been used as drug delivery vehicles for decades. Natural, semisynthetic, and synthetic polymers each one has their own specific characteristic and due to the physicochemical limitations of each polymer tuning the release rate and targeting the active ingredient to a specific organ or site of action is a complicated task for pharmaceutical scientists. In this regard using polymer blends has been considered as an attractive method in which the physical and/or chemical characteristics of different polymers are modified in order to fabricate a novel and unique drug delivery system. There is three major polymers blend that are used for drug delivery purposes including physical mixtures, core-shell model, and block copolymer model. Each of these types of polymer blends could significantly affect the loading capacities and the kinetics of drug release from the relevant formulations. By using appropriate copolymer or polymer blends tuning the release profile would be dependent on the temperature and pH of the environment, and physiochemical properties of the target organs. Also, possible molecular interactions among polymers and drug molecules should be considered. In this review, first of all, the purpose of polymer blending in drug delivery systems has been discussed. Then, different methods of polymer blending have been summarized. Finally, the consequence of each blending method on drug release profile and kinetics of drug release have been discussed.
TL;DR: In this paper, a review summarizes the recent research on 4D printing towards soft tactile sensors and discusses future perspectives for this emerging field, including the use of smart materials through 3D printing manufacturing and programming codes of components and structures to create controllable changes.
Abstract: Soft tactile sensors combine the flexibility and the converting ability between mechanical forces and electrical signals. 4D printing was first introduced in 2013 and attracted great interest because of its versatile functionalities in actuators, artificial muscles, soft tactile sensors, soft energy harvesting, pneumatic nets, electroactive polymers, and soft electronics. Using the 4D printing concept to fabricate soft tactile sensors is promising yet at its infant stage. At present, researchers have utilized two kinds of strategies, one is directly using smart materials through 3D printing manufacturing, and the other is programming codes of components and structures to create controllable changes. This review summarizes the recent research on 4D printing towards soft tactile sensors and discusses future perspectives for this emerging field.
TL;DR: In this paper, the authors proposed a multiple stimuli-responsive shape-shifting strategy with dual stimuli responsive shape shifting that responds to both temperature and water, by using a direct ink writing 3D printing method to deposit a polyurethane elastomer material with water-swelling characteristics on a heat-shrinkage shape memory polymer material to form a bilayer structure.
Abstract: 4D printing has been attracting widespread attention because its shape and performance can change under stimuli. The existing 4D printing technology is mostly limited to responsive to single stimulus, which means that the printing structure can only change under a pre-specified stimulus. Here we propose a 4D printing strategy with dual stimuli-responsive shape-shifting that responds to both temperature and water, by using a direct ink writing 3D printing method to deposit a polyurethane elastomer material with water-swelling characteristics on a heat-shrinkage shape memory polymer material to form a bilayer structure. Based on the systematic study of the adapted printing parameters of the polyurethane elastomer, the effect of programmable variables on the deformation shape was investigated. The diversified printing structure exhibits rich structural changes under one or both of the two stimuli of temperature and humidity. This research provides a universal multiple stimuli-responsive 4D printing method, which can effectively improve the intelligent responsiveness of 4D printing structures by combining multiple smart materials.
TL;DR: In this article, aluminum diethylphosphinate (ADP) combined with expanded graphite (EG) to form a synergistic flame retarded system, which was introduced to fabricate flame retarded rigid polyurethane foam composites by one-step water-blown method.
Abstract: Rigid polyurethane foam (RPUF) was an organic porous material, which was applied in many fields for excellent thermal insulation and mechanical properties, especially in building insulation. However, the poor fire performance significantly suppresses its further application. In this work, aluminum diethylphosphinate (ADP) combined with expanded graphite (EG) to form a synergistic flame retarded system, which was introduced to fabricate flame retarded rigid polyurethane foam composites (FR-RPUF) by one-step water-blown method. Furthermore, thermal insulation, thermal stability, fire performance as well as decomposition products of RPUF and FR-RPUF composites were systematically investigated. It was found that FR-RPUF composites possessed LOI of 25.9 vol% with V-1 rating in UL-94 test when 10 php of ADP and 20 php of EG were added, which were better than RPUF composites with ADP or EG added alone. MCC test showed that RPUF/ADP24/EG6 had the lowest PHRR value of 159.85 W/g, which was 52.01 W/g lower than that of pure RPUF. Gas phase products investigation implied that the combination of ADP and EG could decrease toxic and combustible gases intensities, thus significantly enhance fire safety of FR-RPUF composites. SEM test indicated that ADP and EG promoted the formation of dense and continuous char residue, which significantly inhibited heat and substance transfer in combustion, thus significantly enhance fire performance of FR-RPUF composites.
TL;DR: Di Novo et al. as discussed by the authors proposed a model which involves the minimum number of thermodynamically relevant parameters, such as salt concentration, vapor pressure, and droplet volume, to investigate, at prescribed temperature, how surface energy and ambient humidity cooperate to determine the virus viability.
Abstract: The modeling of the viability decay of viruses in sessile droplets is addressed considering a droplet sitting on a smooth surface characterized by a specific contact angle. To investigate, at prescribed temperature, how surface energy of the material and ambient humidity cooperate to determine the virus viability, we propose a model which involves the minimum number of thermodynamically relevant parameters. In particular, by considering a saline water droplet (one salt) as the simplest approximation of real solutions (medium and natural/artificial saliva), the evaporation is described by a first-order time-dependent nonlinear differential equation properly rearranged to obtain the contact angle evolution as the sole unknown function. The analyses were performed for several contact angles and two typical droplet sizes of interest in real situations by assuming constant ambient temperature and relative humidity in the range 0–100%. The results of the simulations, given in terms of time evolution of salt concentration, vapor pressure, and droplet volume, elucidate some previously not yet well-understood dynamics, demonstrating how three main regimes—directly implicated in nontrivial trends of virus viability and to date only highlighted experimentally—can be recognized as the function of relative humidity. By recalling the concept of cumulative dose of salts (CD), to account for the effect of the exposition of viruses to salt concentration on virus viability, we show how the proposed approach could suggest a chart of a virus fate by predicting its survival time at a given temperature as a function of the relative humidity and contact angle. We found a good agreement with experimental data for various enveloped viruses and predicted in particular for the Phi6 virus, a surrogate of coronavirus, the characteristic U-shaped dependence of viability on relative humidity. Given the generality of the model and once experimental data are available that link the vulnerability of a certain virus, such as SARS-CoV-2, to the concentrations of salts or other substances in terms of CD, it is felt that this approach could be employed for antivirus strategies and protocols for the prediction/reduction of human health risks associated with SARS-CoV-2 and other viruses. © Copyright © 2021 Di Novo, Carotenuto, Mensitieri, Fraldi and Pugno.
TL;DR: In this article, the effect of the mobility of sulfur ions within lead-zinc processing tailings on strength and quality of cemented mine backfills was revealed. And the experimental findings demonstrate that the used cement type and proportions were insufficient and some fractures are occurred in the samples due to the sulfur ion mobility.
Abstract: Predicting the reactions of the backfill materials exposed to the effects of air and groundwater will eventually ensure an efficient and accurate mine fill system for sustainable mining operations. This paper reveals the effect of the mobility of sulfur ions within lead-zinc processing tailings on strength and quality of cemented mine backfills. Some laboratory tests such as X-ray diffraction, ion chromatography, scanning electron microscopy, combustion tests, chemical analysis, pH and zeta potential measurements were performed to better characterize the backfill’s mechanical and microstructural properties. Moreover, CEM II/A-P Portland pozzolan and CEM IV/A pozzolanic cements as ready-to-use cement products were used for cemented mine backfill preparation. To ensure the carrier of the lead-zinc tailings and to prevent the mobility of the sulfurous components, a binder content ranging from 3wt.% to 7wt.% were employed in mine backfills. The experimental findings demonstrate that the used cement type and proportions were insufficient and some fractures are occurred in the samples due to the sulfur ion mobility. Accordingly, one can state clearly that the elemental analysis through the combustion test method can provide fast and reliable results in the determination of sulfur within lead-zinc processing tailings.
TL;DR: In this article, a composite scaffold consisting of SA, chitosan, and hydroxyapatite (HA) was developed to promote the healing of large bone defects, and the results showed that the composite stent carried vascular endothelial growth factor (VEGF), wrapped in internal microspheres, and vancomycin (VAN).
Abstract: Bone scaffolds play an important role in promoting the healing of large bone defects. However, the type of scaffold material, type of drug loaded into the scaffold, and method of preparation have a significant impact on the scaffold’s properties. In this study, we developed a composite scaffold comprising sodium alginate (SA), chitosan (CS), and hydroxyapatite (HA). The composite stent carries vascular endothelial growth factor (VEGF), wrapped in internal microspheres, and vancomycin (VAN). The microspheres are wrapped in an outer matrix formed by SA, CS, and HA, whereas the outer matrix carries VAN. Using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, and scanning electron microscopy analyses, we studied the contraction rate, swelling, porosity, mechanical properties, degradation, and drug release ability of all the composite scaffolds. The best scaffold, as demonstrated by the results of these studies, was the HA6(SA/CS)4@VAN/VEGF scaffold. The antibacterial ability of the HA6(SA/CS)4@VAN/VEGF scaffold was determined using Staphylococcus aureus (S. aureus). Cytotoxicity, cell adhesion, and osteogenic properties of the HA6(SA/CS)4@VAN/VEGF scaffold were studied using bone marrow mesenchymal stem cells. The results indicate that the HA6(SA/CS)4@VAN/VEGF scaffold exhibits good physical, chemical, antibacterial, and osteogenic properties, and is, thus, a new type of bone scaffold composite material with good osteogenic potential.