Showing papers in "Materials in 2020"

Copper-Alloy Surfaces and Cleaning Regimens against the Spread of SARS-CoV-2 in Dentistry and Orthopedics. From Fomites to Anti-Infective Nanocoatings.

Abstract: The latest diffusion of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for the coronavirus disease (COVID-19), has involved the whole world population. Even if huge efforts to control the pandemic have been done, the viral spread is still continuing. COVID-19 is reported as a zoonosis jumped from bats and pangolins to humans. After infection in humans, SARS-CoV-2 is found in the nasopharyngeal and salivary secretions. The virus has also been detected in the blood plasma of infected patients. The viral spread occurs through droplets exhaled from the nose and mouth of the infected people when they breath or talk, or through droplets propelled as a dense cloud by chough or sneeze. The virus can also be delivered as an aerosol from blood plasma, through surgical procedures. Following these ways, the virus can disperse in the air, then reaching and settling on the exposed surfaces. How long the virus will survive on a surface depends on the material the surface is made from. Infection via high-touch surfaces should be prevented. Copper alloy coatings, combined with efficient hygienic/disinfectant procedures and careful surgical practice, could be helpful to health protection in dental practice and can also be adopted in orthopedic traumatology.

Brief History of Early Lithium-Battery Development.

Abstract: Lithium batteries are electrochemical devices that are widely used as power sources. This history of their development focuses on the original development of lithium-ion batteries. In particular, we highlight the contributions of Professor Michel Armand related to the electrodes and electrolytes for lithium-ion batteries.

Environmental impact of food packaging materials: a review of contemporary development from conventional plastics to polylactic acid based materials

Abstract: Plastics have remained the material of choice, and after serving their intended purpose, a large proportion ends up in the environment where they persist for centuries. The packaging industry is the largest and growing consumer of synthetic plastics derived from fossil fuels. Food packaging plastics account for the bulk of plastic waste that are polluting the environment. Additionally, given the fact that petroleum reserves are finite and facing depletion, there is a need for the development of alternative materials that can serve the same purpose as conventional plastics. This paper reviews the function of packaging materials and highlights the future potential of the adoption of green materials. Biopolymers have emerged as promising green materials although they still have very low market uptake. Polylactic acid (PLA) has emerged as the most favoured bioplastic. However, it is limited by its high cost and some performance drawbacks. Blending with agricultural waste and natural fillers can result in green composites at low cost, low greenhouse gas emissions, and with improved performance for food packaging applications. The continent of Africa is proposed as a rich source of fibres and fillers that can be sustainably exploited to fabricate green composites in a bid to achieve a circular economy.

Face masks and respirators in the fight against the COVID-19 pandemic: A review of current materials, advances and future perspectives

Abstract: The outbreak of COVID-19 has spread rapidly across the globe, greatly affecting how humans as a whole interact, work and go about their daily life. One of the key pieces of personal protective equipment (PPE) that is being utilised to return to the norm is the face mask or respirator. In this review we aim to examine face masks and respirators, looking at the current materials in use and possible future innovations that will enhance their protection against SARS-CoV-2. Previous studies concluded that cotton, natural silk and chiffon could provide above 50% efficiency. In addition, it was found that cotton quilt with a highly tangled fibrous nature provides efficient filtration in the small particle size range. Novel designs by employing various filter materials such as nanofibres, silver nanoparticles, and nano-webs on the filter surfaces to induce antimicrobial properties are also discussed in detail. Modification of N95/N99 masks to provide additional filtration of air and to deactivate the pathogens using various technologies such as low- temperature plasma is reviewed. Legislative guidelines for selecting and wearing facial protection are also discussed. The feasibility of reusing these masks will be examined as well as a discussion on the modelling of mask use and the impact wearing them can have. The use of Artificial Intelligence (AI) models and its applications to minimise or prevent the spread of the virus using face masks and respirators is also addressed. It is concluded that a significant amount of research is required for the development of highly efficient, reusable, anti-viral and thermally regulated face masks and respirators.

Tannic Acid with Antiviral and Antibacterial Activity as A Promising Component of Biomaterials—A Minireview

Abstract: As a phenolic acid, tannic acid can be classified into a polyphenolic group. It has been widely studied in the biomedical field of science because it presents unique antiviral as well as antibacterial properties. Tannic acid has been reported to present the activity against Influeneza A virus, Papilloma viruses, noroviruses, Herpes simplex virus type 1 and 2, and human immunodeficiency virus (HIV) as well as activity against both Gram-positive and Gram-negative bacteria as Staphylococcus aureus, Escherichia coli, Streptococcus pyogenes, Enterococcus faecalis, Pseudomonas aeruginosa, Yersinia enterocolitica, Listeria innocua. Nowadays, compounds of natural origin constitute fundaments of material science, and the trend is called “from nature to nature”. Although biopolymers have found a broad range of applications in biomedical sciences, they do not present anti-microbial activity, and their physicochemical properties are rather poor. Biopolymers, however, may be modified with organic and inorganic additives which enhance their properties. Tannic acid, like phenolic acid, is classified into a polyphenolic group and can be isolated from natural sources, e.g., a pure compound or a component of a plant extract. Numerous studies have been carried out over the application of tannic acid as an additive to biopolymer materials due to its unique properties. On the one hand, it shows antimicrobial and antiviral activity, while on the other hand, it reveals promising biological properties, i.e., enhances the cell proliferation, tissue regeneration and wound healing processes. Tannic acid is added to different biopolymers, collagen and polysaccharides as chitosan, agarose and starch. Its activity has been proven by the determination of physicochemical properties, as well as the performance of in vitro and in vivo studies. This systematics review is a summary of current studies on tannic acid properties. It presents tannic acid as an excellent natural compound which can be used to eliminate pathogenic factors as well as a revision of current studies on tannic acid composed with biopolymers and active properties of the resulting complexes.

Recent Trends in the Use of Pectin from Agro-Waste Residues as a Natural-Based Biopolymer for Food Packaging Applications.

Abstract: Regardless of the considerable progress in properties and versatility of synthetic polymers, their low biodegradability and lack of environmentally-friendly character remains a critical issue. Pectin is a natural-based polysaccharide contained in the cell walls of many plants allowing their growth and cell extension. This biopolymer can be extracted from plants and isolated as a bioplastic material with different applications, including food packaging. This review aims to present the latest research results regarding pectin, including the structure, different types, natural sources and potential use in several sectors, particularly in food packaging materials. Many researchers are currently working on a multitude of food and beverage industry applications related to pectin as well as combinations with other biopolymers to improve some key properties, such as antioxidant/antimicrobial performance and flexibility to obtain films. All these advances are covered in this review.

Polyurethane-Based Coatings with Promising Antibacterial Properties

Abstract: In coatings technology, the possibility of introducing specific characteristics at the surface level allows for the manufacture of medical devices with efficient and prolonged antibacterial properties. This efficiency is often achieved by the use of a small amount of antibacterial molecules, which can fulfil their duty while limiting eventual releasing problems. The object of this work was the preparation and characterization of silver, titanium dioxide and chitosan polyurethane-based coatings. Coatings with the three antibacterials were prepared using different deposition techniques, using a brush or a bar coater automatic film applicator, and compared to solvent casted films prepared with the same components. For silver containing materials, an innovative strategy contemplating the use and preparation of silver nanoparticles in a single step-method was employed. This preparation was obtained starting from a silver precursor and using a single compound as the reducing agent and stabilizer. Ultraviolet-visible spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, contact angle measurements and adhesion test experiments were used to characterize the prepared coatings. Promising antibacterial properties, measured via direct and indirect methods, were registered for all the silver-based materials.

Using Deep Learning to Detect Defects in Manufacturing: A Comprehensive Survey and Current Challenges.

Abstract: The detection of product defects is essential in quality control in manufacturing. This study surveys stateoftheart deep-learning methods in defect detection. First, we classify the defects of products, such as electronic components, pipes, welded parts, and textile materials, into categories. Second, recent mainstream techniques and deep-learning methods for defects are reviewed with their characteristics, strengths, and shortcomings described. Third, we summarize and analyze the application of ultrasonic testing, filtering, deep learning, machine vision, and other technologies used for defect detection, by focusing on three aspects, namely method and experimental results. To further understand the difficulties in the field of defect detection, we investigate the functions and characteristics of existing equipment used for defect detection. The core ideas and codes of studies related to high precision, high positioning, rapid detection, small object, complex background, occluded object detection and object association, are summarized. Lastly, we outline the current achievements and limitations of the existing methods, along with the current research challenges, to assist the research community on defect detection in setting a further agenda for future studies.

Progress and Status of Hydrometallurgical and Direct Recycling of Li-Ion Batteries and Beyond.

Abstract: An exponential market growth of Li-ion batteries (LIBs) has been observed in the past 20 years; approximately 670,000 tons of LIBs have been sold in 2017 alone. This trend will continue owing to the growing interest of consumers for electric vehicles, recent engagement of car manufacturers to produce them, recent developments in energy storage facilities, and commitment of governments for the electrification of transportation. Although some limited recycling processes were developed earlier after the commercialization of LIBs, these are inadequate in the context of sustainable development. Therefore, significant efforts have been made to replace the commonly employed pyrometallurgical recycling method with a less detrimental approach, such as hydrometallurgical, in particular sulfate-based leaching, or direct recycling. Sulfate-based leaching is the only large-scale hydrometallurgical method currently used for recycling LIBs and serves as baseline for several pilot or demonstration projects currently under development. Conversely, most project and processes focus only on the recovery of Ni, Co, Mn, and less Li, and are wasting the iron phosphate originating from lithium iron phosphate (LFP) batteries. Although this battery type does not dominate the LIB market, its presence in the waste stream of LIBs causes some technical concerns that affect the profitability of current recycling processes. This review explores the current processes and alternative solutions to pyrometallurgy, including novel selective leaching processes or direct recycling approaches.

Waste Rubber Recycling: A Review on the Evolution and Properties of Thermoplastic Elastomers.

Abstract: Currently, plastics and rubbers are broadly being used to produce a wide range of products for several applications like automotive, building and construction, material handling, packaging, toys, etc. However, their waste (materials after their end of life) do not degrade and remain for a long period of time in the environment. The increase of polymeric waste materials’ generation (plastics and rubbers) in the world led to the need to develop suitable methods to reuse these waste materials and decrease their negative effects by simple disposal into the environment. Combustion and landfilling as traditional methods of polymer waste elimination have several disadvantages such as the formation of dust, fumes, and toxic gases in the air, as well as pollution of underground water resources. From the point of energy consumption and environmental issues, polymer recycling is the most efficient way to manage these waste materials. In the case of rubber recycling, the waste rubber can go through size reduction, and the resulting powders can be melt blended with thermoplastic resins to produce thermoplastic elastomer (TPE) compounds. TPE are multi-functional polymeric materials combining the processability of thermoplastics and the elasticity of rubbers. However, these materials show poor mechanical performance as a result of the incompatibility and immiscibility of most polymer blends. Therefore, the main problem associated with TPE production from recycled materials via melt blending is the low affinity and interaction between the thermoplastic matrix and the crosslinked rubber. This leads to phase separation and weak adhesion between both phases. In this review, the latest developments related to recycled rubbers in TPE are presented, as well as the different compatibilisation methods used to improve the adhesion between waste rubbers and thermoplastic resins. Finally, a conclusion on the current situation is provided with openings for future works.

A Broadband Tunable Terahertz Metamaterial Absorber Based on Single-Layer Complementary Gammadion-Shaped Graphene.

Abstract: We present a simple design of a broadband tunable metamaterial absorber (MMA) in the terahertz (THz) region, which consists of a single layer complementary gammadion-shaped (CGS) graphene sheet and a polydimethylsiloxane (PDMS) dielectric substrate placed on a continuous metal film. The Fermi energy level (Ef) of the graphene can be modulated dynamically by the applied DC bias voltage, which enables us to electrically control the absorption performance of the proposed MMA flexibly. When Ef = 0.8 eV, the relative bandwidth of the proposed MMA, which represents the frequency region of absorption beyond 90%, can reaches its maximal value of 72.1%. Simulated electric field distributions reveal that the broadband absorption mainly originates from the excitation of surface plasmon polaritons (SPPs) on the CGS graphene sheet. Furthermore, the proposed MMA is polarization-insensitive and has wide angles for both transverse-electric (TE) and transverse-magnetic (TM) waves in the broadband frequency range. The broadband absorption capacity of the designed MMA can be effectively adjusted by varying the Fermi energy level of graphene. Lastly, the absorbance of the MMA can be adjusted from 42% to 99.1% by changing the Ef from 0 eV to 0.8 eV, which is in agreement with the theoretical calculation by using the interference 41theory. Due to its simple structure and flexible tunability, the proposed MMA has potential application prospects in tunable filtering, modulators, sensing, and other multispectral devices.

Zinc as a Therapeutic Agent in Bone Regeneration

Abstract: Zinc is an essential mineral that is required for normal skeletal growth and bone homeostasis. Furthermore, zinc appears to be able to promote bone regeneration. However, the cellular and molecular pathways through which zinc promotes bone growth, homeostasis, and regeneration are poorly understood. Zinc can positively affect chondrocyte and osteoblast functions, while inhibiting osteoclast activity, consistent with a beneficial role for zinc in bone homeostasis and regeneration. Based on the effects of zinc on skeletal cell populations and the role of zinc in skeletal growth, therapeutic approaches using zinc to improve bone regeneration are being developed. This review focuses on the role of zinc in bone growth, homeostasis, and regeneration while providing an overview of the existing studies that use zinc as a bone regeneration therapeutic.

Magnetic Iron Oxide Nanoparticle (IONP) Synthesis to Applications: Present and Future.

Abstract: Iron oxides are chemical compounds which have different polymorphic forms, including γ-Fe2O3 (maghemite), Fe3O4 (magnetite), and FeO (wustite). Among them, the most studied are γ-Fe2O3 and Fe3O4, as they possess extraordinary properties at the nanoscale (such as super paramagnetism, high specific surface area, biocompatible etc.), because at this size scale, the quantum effects affect matter behavior and optical, electrical and magnetic properties. Therefore, in the nanoscale, these materials become ideal for surface functionalization and modification in various applications such as separation techniques, magnetic sorting (cells and other biomolecules etc.), drug delivery, cancer hyperthermia, sensing etc., and also for increased surface area-to-volume ratio, which allows for excellent dispersibility in the solution form. The current methods used are partially and passively mixed reactants, and, thus, every reaction has a different proportion of all factors which causes further difficulties in reproducibility. Direct active and complete mixing and automated approaches could be solutions to this size- and shape-controlled synthesis, playing a key role in its exploitation for scientific or technological purposes. An ideal synthesis method should be able to allow reliable adjustment of parameters and control over the following: fluctuation in temperature; pH, stirring rate; particle distribution; size control; concentration; and control over nanoparticle shape and composition i.e., crystallinity, purity, and rapid screening. Iron oxide nanoparticle (IONP)-based available clinical applications are RNA/DNA extraction and detection of infectious bacteria and viruses. Such technologies are important at POC (point of care) diagnosis. IONPs can play a key role in these perspectives. Although there are various methods for synthesis of IONPs, one of the most crucial goals is to control size and properties with high reproducibility to accomplish successful applications. Using multiple characterization techniques to identify and confirm the oxide phase of iron can provide better characterization capability. It is very important to understand the in-depth IONP formation mechanism, enabling better control over parameters and overall reaction and, by extension, properties of IONPs. This work provides an in-depth overview of different properties, synthesis methods, and mechanisms of iron oxide nanoparticles (IONPs) formation, and the diverse range of their applications. Different characterization factors and strategies to confirm phase purity in the IONP synthesis field are reviewed. First, properties of IONPs and various synthesis routes with their merits and demerits are described. We also describe different synthesis strategies and formation mechanisms for IONPs such as for: wustite (FeO), hematite (α-Fe2O3), maghemite (ɤ-Fe2O3) and magnetite (Fe3O4). We also describe characterization of these nanoparticles and various applications in detail. In conclusion, we present a detailed overview on the properties, size-controlled synthesis, formation mechanisms and applications of IONPs.

Glass-Ceramics in Dentistry: A Review.

Abstract: In this review, we first briefly introduce the general knowledge of glass–ceramics, including the discovery and development, the application, the microstructure, and the manufacturing of glass–ceramics. Second, the review presents a detailed description of glass–ceramics in dentistry. In this part, the history, property requirements, and manufacturing techniques of dental glass–ceramics are reviewed. The review provided a brief description of the most prevalent clinically used examples of dental glass–ceramics, namely, mica, leucite, and lithium disilicate glass–ceramics. In addition, we also introduce the newly developed ZrO2–SiO2 nanocrystalline glass–ceramics that show great potential as a new generation of dental glass–ceramics. Traditional strengthening mechanisms of glass–ceramics, including interlocking, ZrO2–reinforced, and thermal residual stress effects, are discussed. Finally, a perspective and outlook for future directions in developing new dental glass–ceramics is provided to offer inspiration to the dental materials community.

Circular Economy on Construction and Demolition Waste: A Literature Review on Material Recovery and Production

Abstract: Construction and demolition waste (CDW) accounts for at least 30% of the total solid waste produced around the world. At around 924 million tons in the European Union in 2016 and 2.36 billion tons in China in 2018, the amount is expected to increase over the next few years. Dumping these wastes in sanitary landfills has always been the traditional approach to waste management but this will not be feasible in the years to come. To significantly reduce or eliminate the amount of CDW being dumped, circular economy is a possible solution to the increasing amounts of CDW. Circular economy is an economic system based on business models which replaces the end-of-life concept with reducing, reusing, recycling, and recovering materials. This paper discusses circular economy (CE) frameworks-specifically material recovery and production highlighting the reuse and recycling of CDW and reprocessing into new construction applications. Likewise, a literature review into recent studies of reuse and recycling of CDW and its feasibility is also discussed to possibly prove the effectivity of CE in reducing CDW. Findings such as effectivity of recycling CDW into new construction applications and its limitations in effective usage are discussed and research gaps such as reuse of construction materials are also undertaken. CE and recycling were also found to be emerging topics. Observed trends in published articles as well as the use of latent Dirichlet allocation in creating topic models have shown a rising awareness and increasing research in CE which focuses on recycling and reusing CDW.

Selection of Collagen Membranes for Bone Regeneration: A Literature Review

Abstract: Several treatment modalities have been proposed to regenerate bone, including guided bone regeneration (GBR) where barrier membranes play an important role by isolating soft tissue and allowing bone to grow. Not all membranes biologically behave the same way, as they differ from their origin and structure, with reflections on their mechanical properties and on their clinical performance. Collagen membranes have been widely used in medicine and dentistry, because of their high biocompatibility and capability of promoting wound healing. Recently, collagen membranes have been applied in guided bone regeneration with comparable outcomes to non-resorbable membranes. Aim of this work is to provide a review on the main features, application, outcomes, and clinical employment of the different types of collagen membranes. Comparisons with non-resorbable membranes are clarified, characteristics of cross-linked collagen versus native collagen, use of different grafting materials and need for membrane fixation are explored in order to gain awareness of the indications and limits and to be able to choose the right membrane required by the clinical condition.

Phase Change Materials Application in Battery Thermal Management System: A Review.

Abstract: The purpose of a battery thermal management system (BTMS) is to maintain the battery safety and efficient use as well as ensure the battery temperature is within the safe operating range. The traditional air-cooling-based BTMS not only needs extra power, but it could also not meet the demand of new lithium-ion battery (LIB) packs with high energy density, while liquid cooling BTMS requires complex devices to ensure the effect. Therefore, phase change materials (PCMs)-based BTMS is becoming the trend. By using PCMs to absorb heat, the temperature of a battery pack could be kept within the normal operating range for a long time without using any external power. PCMs could greatly improve the heat dissipation efficiency of BTMS by combining with fillers such as expanded graphite (EG) and metal foam for their high thermal conductivity or coordinating with fins. In addition, PCMs could also be applied in construction materials, solar thermal recovery, textiles and other fields. Herein, a comprehensive review of the PCMs applied in thermal storage devices, especially in BTMS, is provided. In this work, the literature concerning current issues have been reviewed and summarized, while the key challenges of PCM application have been pointed out. This review may bring new insights to the PCM application.

A Review on Membrane Technology and Chemical Surface Modification for the Oily Wastewater Treatment

Abstract: Cleaning of wastewater for the environment is an emerging issue for the living organism. The separation of oily wastewater, especially emulsified mixtures, is quite challenged due to a large amount of wastewater produced in daily life. In this review, the membrane technology for oily wastewater treatment is presented. In the first part, the global membrane market, the oil spill accidents and their results are discussed. In the second and third parts, the source of oily wastewater and conventional treatment methods are represented. Among all methods, membrane technology is considered the most efficient method in terms of high separation performance and easy to operation process. In the fourth part, we provide an overview of membrane technology, fouling problem, and how to improve the self-cleaning surface using functional groups for effectively treating oily wastewater. The recent development of surface-modified membranes for oily wastewater separation is investigated. It is believed that this review will promote understanding of membrane technology and the development of surface modification strategies for anti-fouling membranes.

Advances in Orthotic and Prosthetic Manufacturing: A Technology Review.

Abstract: In this work, the recent advances for rapid prototyping in the orthoprosthetic industry are presented. Specifically, the manufacturing process of orthoprosthetic aids are analysed, as thier use is widely extended in orthopedic surgery. These devices are devoted to either correct posture or movement (orthosis) or to substitute a body segment (prosthesis) while maintaining functionality. The manufacturing process is traditionally mainly hand-crafted: The subject’s morphology is taken by means of plaster molds, and the manufacture is performed individually, by adjusting the prototype over the subject. This industry has incorporated computer aided design (CAD), computed aided engineering (CAE) and computed aided manufacturing (CAM) tools; however, the true revolution is the result of the application of rapid prototyping technologies (RPT). Techniques such as fused deposition modelling (FDM), selective laser sintering (SLS), laminated object manufacturing (LOM), and 3D printing (3DP) are some examples of the available methodologies in the manufacturing industry that, step by step, are being included in the rehabilitation engineering market—an engineering field with growth and prospects in the coming years. In this work we analyse different methodologies for additive manufacturing along with the principal methods for collecting 3D body shapes and their application in the manufacturing of functional devices for rehabilitation purposes such as splints, ankle-foot orthoses, or arm prostheses.

Effect of Coconut Fiber Length and Content on Properties of High Strength Concrete.

Abstract: Recently, the addition of natural fibers to high strength concrete (HSC) has been of great interest in the field of construction materials. Compared to artificial fibers, natural fibers are cheap and locally available. Among all natural fibers, coconut fibers have the greatest known toughness. In this work, the mechanical properties of coconut fiber reinforced high strength concrete (CFR-HSC) are explored. Silica fume (10% by mass) and super plasticizer (1% by mass) are also added to the CFR-HSC. The influence of 25 mm-, 50 mm-, and 75 mm-long coconut fibers and 0.5%, 1%, 1.5%, and 2% contents by mass is investigated. The microstructure of CFR-HSC is studied using scanning electron microscopy (SEM). The experimental results revealed that CFR-HSC has improved compressive, splitting-tensile, and flexural strengths, and energy absorption and toughness indices compared to HSC. The overall best results are obtained for the CFR-HSC having 50 mm long coconut fibers with 1.5% content by cement mass.

A Review of Conductive Hydrogel Used in Flexible Strain Sensor.

Abstract: Hydrogels, as classic soft materials, are important materials for tissue engineering and biosensing with unique properties, such as good biocompatibility, high stretchability, strong adhesion, excellent self-healing, and self-recovery. Conductive hydrogels possess the additional property of conductivity, which endows them with advanced applications in actuating devices, biomedicine, and sensing. In this review, we provide an overview of the recent development of conductive hydrogels in the field of strain sensors, with particular focus on the types of conductive fillers, including ionic conductors, conducting nanomaterials, and conductive polymers. The synthetic methods of such conductive hydrogel materials and their physical and chemical properties are highlighted. At last, challenges and future perspectives of conductive hydrogels applied in flexible strain sensors are discussed.

Printed Electronics as Prepared by Inkjet Printing.

Abstract: Inkjet printing has been used to produce a range of printed electronic devices, such as solar panels, sensors, and transistors. This article discusses inkjet printing and its employment in the field of printed electronics. First, printing as a field is introduced before focusing on inkjet printing. The materials that can be employed as inks are then introduced, leading to an overview of wetting, which explains the influences that determine print morphology. The article considers how the printing parameters can affect device performance and how one can account for these influences. The article concludes with a discussion on adhesion. The aim is to illustrate that the factors chosen in the fabrication process, such as dot spacing and sintering conditions, will influence the performance of the device.

Methods for Reducing the Toxicity of Metal and Metal Oxide NPs as Biomedicine.

Abstract: The rapid development of medicine has forced equally rapid progress in the field of pharmaceuticals. In connection with the expensive and time-consuming process of finding new drugs, great emphasis is put on the design and use of metal and metal oxides nanoparticles in nanomedicine. The main focus is on comprehensive presentation of both physicochemical properties and the possibilities of using, in particular, silver (Ag) and gold (Au) nanoparticles, as well as zinc oxide (ZnO) and titanium oxide (TiO2) nanoparticles as drug carriers and in the treatment of cancer. An important element of this subject is the possibility of occurrence of toxic effects of these nanoparticles. For this reason, possible mechanisms of toxic actions are presented, as well as methods used to reduce their toxicity to ensure the safety of drug carriers based on these nanostructures.

Electrospun Nano-Fibers for Biomedical and Tissue Engineering Applications: A Comprehensive Review

Abstract: Pharmaceutical nano-fibers have attracted widespread attention from researchers for reasons such as adaptability of the electro-spinning process and ease of production. As a flexible method for fabricating nano-fibers, electro-spinning is extensively used. An electro-spinning unit is composed of a pump or syringe, a high voltage current supplier, a metal plate collector and a spinneret. Optimization of the attained nano-fibers is undertaken through manipulation of the variables of the process and formulation, including concentration, viscosity, molecular mass, and physical phenomenon, as well as the environmental parameters including temperature and humidity. The nano-fibers achieved by electro-spinning can be utilized for drug loading. The mixing of two or more medicines can be performed via electro-spinning. Facilitation or inhibition of the burst release of a drug can be achieved by the use of the electro-spinning approach. This potential is anticipated to facilitate progression in applications of drug release modification and tissue engineering (TE). The present review aims to focus on electro-spinning, optimization parameters, pharmacological applications, biological characteristics, and in vivo analyses of the electro-spun nano-fibers. Furthermore, current developments and upcoming investigation directions are outlined for the advancement of electro-spun nano-fibers for TE. Moreover, the possible applications, complications and future developments of these nano-fibers are summarized in detail.

IR Study on Cellulose with the Varied Moisture Contents: Insight into the Supramolecular Structure.

Abstract: The following article is the first attempt to investigate the supramolecular structure of cellulose with the varied moisture content by the means of Fourier-transform and near infrared spectroscopy techniques. Moreover, authors aimed at the detailed and precise presentation of IR spectra interpretation approach in order to create a reliable guideline for other researchers. On the basis of obtained data, factors indicating biopolymer crystallinity and development of hydrogen interactions were calculated and the peaks representing hydrogen bonding (7500-6000 cm-1, 3700-3000 cm-1, and 1750-1550 cm-1) were resolved using the Gaussian distribution function. Then, the deconvoluted signals have been assigned to the specific interactions occurring at the supramolecular level and the hydrogen bond length, as well bonding-energy were established. Furthermore, not only was the water molecules adsorption observed, but also the possibility of the 3OH⋯O5 intramolecular hydrogen bond shortening in the wet state was found-from (27,786 ± 2) 10-5 nm to (27,770 ± 5) 10-5 nm. Additionally, it was proposed that some deconvoluted signals from the region of 3000-2750 cm-1 might be assigned to the hydroxyl group-incorporated hydrogen bonding, which is, undoubtedly, a scientific novelty as the peak was not resolved before.

Recent Developments in the Flame-Retardant System of Epoxy Resin.

Abstract: With the increasing emphasis on environmental protection, the development of flame retardants for epoxy resin (EP) has tended to be non-toxic, efficient, multifunctional and systematic. Currently reported flame retardants have been capable of providing flame retardancy, heat resistance and thermal stability to EP. However, many aspects still need to be further improved. This paper reviews the development of EPs in halogen-free flame retardants, focusing on phosphorus flame retardants, carbon-based materials, silicon flame retardants, inorganic nanofillers, and metal-containing compounds. These flame retardants can be used on their own or in combination to achieve the desired results. The effects of these flame retardants on the thermal stability and flame retardancy of EPs were discussed. Despite the great progress on flame retardants for EP in recent years, further improvement of EP is needed to obtain numerous eco-friendly high-performance materials.

Shape Memory Alloys for Aerospace, Recent Developments, and New Applications: A Short Review

Abstract: Shape memory alloys (SMAs) show a particular behavior that is the ability to recuperate the original shape while heating above specific critical temperatures (shape memory effect) or to withstand high deformations recoverable while unloading (pseudoelasticity). In many cases the SMAs play the actuator's role. Starting from the origin of the shape memory effect, the mechanical properties of these alloys are illustrated. This paper presents a review of SMAs applications in the aerospace field with particular emphasis on morphing wings (experimental and modeling), tailoring of the orientation and inlet geometry of many propulsion system, variable geometry chevron for thrust and noise optimization, and more in general reduction of power consumption. Space applications are described too: to isolate the micro-vibrations, for low-shock release devices and self-deployable solar sails. Novel configurations and devices are highlighted too.

Melt-Spun Fibers for Textile Applications

Abstract: Textiles have a very long history, but they are far from becoming outdated. They gain new importance in technical applications, and man-made fibers are at the center of this ongoing innovation. The development of high-tech textiles relies on enhancements of fiber raw materials and processing techniques. Today, melt spinning of polymers is the most commonly used method for manufacturing commercial fibers, due to the simplicity of the production line, high spinning velocities, low production cost and environmental friendliness. Topics covered in this review are established and novel polymers, additives and processes used in melt spinning. In addition, fundamental questions regarding fiber morphologies, structure-property relationships, as well as flow and draw instabilities are addressed. Multicomponent melt-spinning, where several functionalities can be combined in one fiber, is also discussed. Finally, textile applications and melt-spun fiber specialties are presented, which emphasize how ongoing research efforts keep the high value of fibers and textiles alive.

Review on the Biological Degradation of Polymers in Various Environments.

Abstract: Biodegradable plastics can make an important contribution to the struggle against increasing environmental pollution through plastics. However, biodegradability is a material property that is influenced by many factors. This review provides an overview of the main environmental conditions in which biodegradation takes place and then presents the degradability of numerous polymers. Polylactide (PLA), which is already available on an industrial scale, and the polyhydroxyalkanoates polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-valerate (PHBV), which are among the few plastics that have been proven to degrade in seawater, will be discussed in detail, followed by a summary of the degradability of further petroleum-, cellulose-, starch-, protein- and CO2-based biopolymers and some naturally occurring polymers.

Production of Sustainable Construction Materials Using Agro-Wastes

Abstract: The construction sector, in modern times, is faced by a myriad of challenges primarily due to the increase in the urban population and dwindling natural resources that facilitate the production of construction materials. Furthermore, higher awareness on climate change is forcing companies to rethink their strategies in developing more sustainable construction materials. Diverse types of agro-waste ranging from rice husk ash (RHA), sugarcane bagasse ash (SCBA), and bamboo leaves ash (BLA) among others have been identified as potent solutions in the development of sustainable construction materials. In this review paper, six different construction materials, made using agro-waste products, are examined. The materials include brick/masonry elements, green concrete, insulation materials for buildings, reinforcement materials for buildings, particleboards, and bio-based plastics. The main criterion adopted in selecting the materials regards their popularity and wide-scale use in modern construction applications. Additionally, as this research emphasizes identifying alternative approaches to develop sustainable construction materials, the focus is directed toward mainstream materials whose continued use has an adverse impact on the environment. The findings obtained from the review showed that the use of agro-waste to develop sustainable construction materials was effective, as the developed materials adhered to established building standards. Therefore, this indicates that agro-waste materials have the potential to replace conventional construction materials and hence achieve economic, environmental, and social sustainability in the long run.