This paper focuses on the current status and significance of research on flame-retardant modified polycarbonate/acrylonitrile butadiene styrene alloys (PC/ABS). PC/ABS alloys, as a kind of widely used modified engineering plastics, have many advantages, but their poor flame-retardant properties limit the applications. Flame retardants can give flammable polymers flame retardant properties and reduce the risk of fire, thereby mitigating potential environmental damage from uncontrolled burning and toxic fume release. This review focuses on the current research status of additive flame retardants, which are the most widely used in the current market, mainly including phosphorus-based, silicone-based and synergistic flame retardants. This review finds that in the future, flame retardant PC/ABS will develop in the direction of increasing market demand, improving environmental protection requirements (e.g., seeking halogen-free alternatives and enhancing material recyclability), and relying on technological innovations such as nanomaterials and renewable additives to optimize flame retardancy and overall performance. These advancements contribute significantly to developing safer and more environmentally sustainable materials.
Sea urchin spines are of interest for biomaterials and functional materials development due to their mechanical properties, which depend on their elemental composition. However, no previous study has examined the structural distinctions between the spines in the ambulacral and interambulacral areas. This study addresses that gap by investigating the structural and mechanical differences in the spines of Strongylocentrotus nudus , with a focus on these two areas. We used cantilever bending tests, Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and inductively coupled plasma atomic emission spectroscopy (ICP-AES) to analyze the composition, elasticity, and microstructure of the spines. The bending modulus of elasticity was higher in the ambulacral area (52.067 GPa) compared to the interambulacral area (10.133 GPa), hardness and deformation. ICP-AES analysis revealed that ambulacral shaft had a slightly higher concentration of magnesium (Mg) (0.9844 wt%) compared to the interambulacral shaft (0.9804 wt%), while the calcium (Ca) concentration was lower in the ambulacral shaft (39.6578 wt%) compared to the interambulacral shaft (42.1076 wt%). Furthermore, a variation in Mg concentration was observed between the base and shaft parts of the spine. XRD showed a narrower (104) lattice spacing in the ambulacral spine (3.0264 Å) compared to the interambulacral spine (3.0275 Å), correlating with higher Mg concentration. These compositional and structural differences suggested that S. nudus modulates Mg concentration in calcite to achieve functional specialization of spines for locomotion and defense. Our findings may be useful for the development of novel functional materials.
Heavy-metal extraction using physically modified zeolites with reducing agents, subject to static magnetism and bioremediation, remains largely unexplored. Here, we partly gel-coated ZSM-5 pellets with zinc and tested their copper extraction from a polluted medium, with and without a neodymium magnet and/or a bio-trap (Vicia faba). The reinforced zeolite accrued the fastest extraction, outperforming the raw zeolite and the bio-trap, especially as time advanced. The reinforced zeolite, accompanied by the bio-trap, was the most effective over time, followed by having both companions (the magnet and the bio-trap) present. Having the magnet as a solo companion of the reinforced zeolite extracted more copper compared to the raw zeolite; but slightly yielded lesser than having the reinforced companionless. Interestingly, the bio-trap was a better companion than the magnet, and, after 20 min, having both companions was more beneficial than having the magnet alone, but less yielding than having the bio-trap alone in the long term, indicating a synergistic effect between the reinforced zeolite and the bio-trap. Further characterisation underscored stable yet differential ZSM-5 performance. Additionally, we plasma-sputtered ZSM-5 pellets with zinc, and tested their copper extraction under the magnet. That led to promising early results, despite a sharply deteriorated extraction efficacy over time, as more extraction was achieved than the cases of the raw zeolite, or the reinforced zeolite minus the magnet, with almost identical outcome compared to the reinforced zeolite plus the magnet. Our amalgamative approach provides novel user-friendly extraction methods, with high applicability potential across aquatic media and heavy metals.
Background Three-dimensional (3D) printing technologies have gained increasing popularity in restorative dentistry for fabricating polymer-based restorations. However, limited evidence exists regarding the bond strength between 3D-printed restorative materials and resin cements, particularly considering the effects of surface treatments and aging conditions. This meta-analysis aimed to synthesize the current knowledge on the adhesion of 3D-printed restorations to resin cements and identify areas for future research. Methodology A literature search was conducted in PubMed, Google Scholar, and Web of Science databases using the following keywords: “3D - printing”, “additive manufacturing”, “bond strength”, “resin cement”, “surface treatment”, and “aging”. Inclusion criteria were studies evaluating the bond strength of 3D-printed polymer restorative materials to resin cements, published in English, and with full-text availability. Data on bond strength values, failure modes, surface treatments, aging protocols, and material characterization were extracted and analyzed. Results Nine studies were included in the review. Digital light processing (DLP) and stereolithography (SLA) were the predominant 3D printing technologies. Airborne-particle abrasion (APA) with 50 µm aluminum oxide particles was used in five studies and significantly improved bond strengths compared to untreated controls. Chemical treatments such as silane coupling agents and universal adhesives containing 10-MDP were used in some studies and further enhanced adhesion when combined with APA. Thermocycling for 5,000 cycles, simulating 6 months of clinical service, was the most common aging protocol. Bond strengths generally decreased after aging, with some material and surface treatment combinations showing greater stability than others. Conclusions APA is an effective surface treatment method for improving the bond strength of 3D-printed polymer restorations to resin cement. The combination of mechanical treatment with chemical agents such as silane and 10-MDP provides additional benefits. Material composition, particularly the use of UDMA-based resins, significantly influences bond stability after aging. Standardized protocols for 3D-printing, post-processing, and testing methods are essential for consistent results. Further clinical investigations are needed to establish long-term performance guidelines and optimize bonding protocols for these innovative restorative materials.
Natural fibers are classified as green energy materials and have embodied the principles of sustainable development. This paper impregnated natural continuous flax fibers (CFF) with polyethylene (PE) on a self-developed melt impregnation device, obtained CFF/PE prepreg filaments. A fused deposition machine was used to 3D print CFF/PE composites. The effect of impregnation temperature on tensile properties of CFF/PE filaments was explored. The influence of various 3D printing parameters on bending performance and dimensional accuracy of CFF/PE composites was investigated. The results indicated that the tensile strength of the prepreg filament reached to the maximum value (12.41 MPa) at impregnation temperatures of 150 °C–155 °C. At a layer width of 1.5 mm, a layering thickness of 0.8 mm, a printing speed of 10 mm/min, and a printing temperature of 200 °C, the flexural strength of CFF/PE composites was improved to 24.74 MPa from 13.14 MPa. When the layer width was 2.0 mm and the layer thickness was 0.6 mm, the porosity was reduced to 3.88%. At a layer width of 1.5 mm, severe polymer accumulation occurred between adjacent printing lines, resulting in a significant impact on the dimensional accuracy of the composites. The maximum deviation was approximately 1.45 × 0.57 × 2.32 (mm). As the number of bendings increased, the bending rebound angle decreased, and the bending performance deteriorated, until it kept level.
In this study we present the synthesis of erbium, ytterbium and erbium-ytterbium nanoparticles supported on multiwalled carbon nanotubes by a microwave-assisted method as well as the evaluation of their luminescent properties. In the case of erbium, nanoparticles of ~1 nm homogeneously dispersed on the carbon nanotubes were obtained. In the case of ytterbium, the carbon nanotubes were partially coated with this metal. Clusters of erbium-ytterbium nanoparticles were obtained in the co-deposition of both metals. The erbium-ytterbium/carbon nanotube composite showed both down- and up-conversion luminescence. For the down-conversion process, strong emission signals at 523, 530 and 563 nm as well as a weak signal at 612 nm under 488 nm excitation are observed. For the up-conversion process, the composite showed emission signals centered at 528 and 660 nm under 980 nm excitation.
Quantum dots (QDs) are very attractive nanostructures from an application point of view due to their unique optical properties. Optical properties and valence band (VB) state character was numerically investigated with respect to the effects of nanostructure geometry and composition. Numerical simulation was carried out using the Luttinger–Kohn model adapted to the particular case of QDs in inverted pyramids. We present the source code of the 4-band Luttinger–Kohn model that can be used to model AlGaAs or InGaAs nanostructures. The work focuses on the optical properties of GaAs/AlGaAs [111] QDs and quantum dot molecules (QDMs). We examine the dependence of Ground State (GS) optical properties on the structural parameters and predict optimal parameters of the QD/QDM systems to achieve dynamic control of GS polarization by an applied electric field.
In this study, demagnetization heat treatment at 100 ∼400 °C is studied by using computer simulation to secure the optimal demagnetization heat treatment conditions for waste neodymium iron boron (NdFeB) permanent magnets. From the computer simulation, the temperature of the magnet during heat treatment is higher than the set temperature by up to 6 °C. Delay time occurs when the furnace internal temperature and magnet temperature reached the set temperature. A delay time of 15 minutes in an air atmosphere and 10 minutes in a nitrogen atmosphere occurs. The Nd magnet was completely demagnetized at 300 °C as the magnetic flux decreased when the heat treatment temperature increased up to 250 °C. The fully demagnetized magnet could be magnetized to the level of a new magnet. It was confirmed that NdFeB magnets heat treated up to 350 °C in a nitrogen atmosphere can be reusable due to stable demagnetization being possible without surface change.
The potential applications of fungi in the development of new biomaterials derived from fungal mycelium have captured the attention from both the scientific community and the society. The notable ability of mycelium networks to self-construct and aggregate can be used to produce diverse biomaterials. These biomaterials can be created in a pure state, or both in conjunction with other organic/inorganic compounds. Recent advancements in mycomaterials have gained attention due to their sustainability and mechanical, thermogravimetric, and compression properties. Such properties contribute to reducing the reliance on environmentally problematic substrates within the industry. After a standardized and comprehensive review of publications on mycomaterials across different fields, such as biology, health, agriculture, engineering, and material sciences, we detected that publications on this theme are utterly scattered. This critical review enabled us to also propose a novel classification system for these fungal-derived materials to help to structure and standardize this emerging transdisciplinary field of knowledge.
Mercury is a natural, long-lasting, and bio-accumulative contaminant found in both soil and water. Mercury is toxic and its organic derivative, methylmercury (MeHg), could be lethal. The increasing level of mercury in the environment is a threat, as it can easily enter the food chain upon exposure. Zero-valent iron nanoparticle (nZVI), an environmentally friendly nanomaterial, is envisaged as an ideal candidate for the remediation of metal pollutions in soil and water bodies. Due to low toxicity and decent activity, nZVI and its corrosion products have shown huge potential for the removal of heavy metals from soil and water. It has been widely applied for the removal of heavy metals including mercury and other organic and inorganic contaminants. In this review, the current preparation methodology, characterization techniques, reductive mechanism for heavy metal removal with focus on mercury is reviewed. This review discusses the use of nZVI for the removal of mercury and demonstrates that nZVI possesses high reactivities for mercury removal and have great application prospects in environmental remediation. Some recommendations are proposed and conclusions drawn for future research.
The optoelectronic properties of free standing monolayer (ML) hexagonal boron nitride (h-BN) is investigated for potential solar energy conversion applications using the density functional theory (DFT) full potential linearized augmented plane wave (FP-LAPW) method. In addition, the bulk optical properties have also been calculated for the sake of comparison. The dielectric functions, optical conductivities and the optical constants are evaluated using the relaxed structures from electronic total energy pseudopotential calculations. The results reinforce previous research on h-BN DUV optoelectronics and demonstrate the suitability of its use as a component in deep ultraviolet (DUV) and energy conversion devices.
Background The COVID-19 pandemic brought forth the crucial roles of personal protective equipment (PPE) such as face masks and shields. Additive manufacturing with 3D printing enabled customization and generation of transparent PPEs. However, these devices were prone to condensation from normal breathing. This study was motivated to seek a safe, non-toxic, and durable anti-fogging solution. Methods We used additive 3D printing to generate the testing apparatus for contact angle, sliding angle, and surface contact testing. We examined several formulations of carnauba wax to beeswax in different solvents and spray-coated them on PETG transparent sheets to test contact and sliding angle, and transmittance. Further, the integrity of this surface following several disinfection methods such as detergent, isopropyl alcohol, or water alone with gauze, paper towels, and microfiber, along with disinfectant wipes, was assessed. Results The results indicate a 1:2 ratio of carnauba to beeswax in Acetone optimally generated a highly hydrophobic surface (contact angle 150.3 ± 2.1° and sliding angle 13.7 ± 2.1°) with maximal transmittance. The use of detergent for disinfection resulted in the complete removal of the anti-fogging coating, while isopropyl alcohol and gauze optimally maintained the integrity of the coated surface. Finally, the contact surface testing apparatus generated a light touch (5,000 N/m2) that demonstrated good integrity of the antifogging surface. Conclusions This study demonstrates that a simple natural wax hydrophobic formulation can serve as a safe, non-toxic, and sustainable anti-fogging coating for clear PPEs compared to several commercial solutions.
Bismuth titanate syntheses using wet chemical methods are comparatively time-consuming and require long durations for completion using the well-studied sol-gel method. In this work, we use microwave initiated combustion method to produce ultra-thin bismuth titanate nanosheets. This method reduces the time required for the synthesis down to minutes, when compared to hours or days in most other methods. The thickness of the synthesized sheets were tuned by adding polyethylene glycol as a capping agent, which in turn affects the band gap and subsequently, their photocatalytic properties. The samples were characterized using x-ray diffraction, transmission electron microscopy and absorption spectrophotometry. Photocatalytic effect of the synthesized bismuth titanate nanosheets on methylene blue dye also studied and variation of band gap depending on thickness of the nanosheets were observed.
In this study new TiO2 photocatalysts core@shell type were synthesized using SiO2 as structural support. The coating was confirmed by scanning electron microscopy and infrared spectroscopy. Adsorption isotherms revealed that the surface area of such composites is about 26% higher than pure oxide (W50). X-ray diffractograms combined with Raman spectroscopy revealed that the synthesized TiO2 presents a structure based on the coexistence of anatase and brookite. The composite W50S50 presented the best photocatalytic performance of H2 production, with 13.5 mmol in 5 h, corresponding to a specific rate of 32.5 mmol h−1g−1. In the reuse assays, this composite presented a good stability in the production of H2. However, its performance presented a reduction of 23% over the reuse cycles. Considering the H2 production in a solar simulator, W50S50 produced about 25.0 μmols, which is equivalent to 48.0 μmols h−1g−1, suggesting the good performance of this material for photocatalytic hydrogen production.
A method where particulates are transferred via a cosmetic brush onto liquid drops created on a highly non-wetting substrate with a hole to generate talc and graphite liquid marbles (LMs) and talc-graphite Janus liquid marbles is described. van der Waals forces facilitated the attachment of particulates to the dry brush bristles. Subsequently, the surface tension forces that developed from particle interaction with water (which were O(102) higher than the van der Waals forces) could then engender transfer of the particulates to the liquid-gas interface of the drop. Forces below 1 mN applied by a dangling foil on the LM ensured preservation of the drop shape when the force was removed. During the application of this force, the contact angles at the contact lines behaved differently from sessile drops that are inclined on surfaces. This preparation method portends the ability to automate the creation of LMs and Janus LMs for various applications.
Rare earth hydroxides have a wide variety of applications due to their interesting optical and magnetic properties. Specifically, yttrium hydroxide Y(OH)3 is an essential compound of rare earth hydroxides that can be used in areas such as electronics and chemistry due to its optical and structural properties. In this work Y(OH)3 was synthesized under nine reaction times (2–24 h) using the hydrothermal method in order to analyze the morphology evolution process that the Y(OH)3 follow to obtain the expected bar morphology. Also, a characterization study of Y(OH)3 through several techniques such as x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, infrared, Raman and UV-Vis spectroscopy, thermogravimetric analysis, and differential scanning calorimetry is presented. The obtained samples in every reaction time were compared on phase purity, particle size and shape, and spectroscopic and thermal properties. It was concluded that the reaction time has an important effect in obtaining yttrium hydroxide using the hydrothermal method. During the study, the optimal time to obtain only Y(OH)3 was evaluated, as well as the evolution of the morphology over time. At 12 hours, only Y(OH)3is obtained, therefore this time is proposed as the optimal time.
In this work polystyrene nanoparticles (PS NPs) were fabricated from an emulsion of PS/toluene in water using various surfactants, and purified via dialysis in a simple procedure. The synthesis process was carried out at room temperature, without hazardous chemicals, and with a workload of 5 hours. The investigation was performed to evaluate the limits for production of PS NPs with comparable properties. A robust PS NP synthesis procedure was developed, repeated, and tested by three independent researches. The procedure was up-scaled to prove the applicability of the method and the NPs were prepared with four different hydrophobic dyes. All products were found to be comparable, and it was concluded that the method reported here can provide PS NPs with or without dye dopants, and that it provides access to PS NPs with an average diameter of 25 nm in a reproducible size distribution.
Background The NOVARON, a silver-based antimicrobial agent derived from inorganic ion exchangers developed by Toagosei and registered by FDA, has effectively indicated the antimicrobial power of silver against a variety of microbes. The objective of this study was to investigate the effect of a silver-supported material (Novaron (N)) on the mechanical behaviour, antimicrobial properties, cytotoxicity and colour of light-cured resin composites. Methods Silanized aluminum borate whisker (ABWs) (4 wt%) and nano-zirconia (nano-ZrO 2 ) (2 wt%) were mixed with the resin matrix to obtain the control groups; 4 wt% surface-modified Novaron particles were incorporated into the above matrices as the experimental groups. The surface hardness was tested. Furthermore, the antimicrobial abilities evaluated in vitro with Streptococcus mutans ( S. mutans ), Fusobacterium nucleatum ( F. nucleatum ) and Candida albicans ( C. albicans ) using the live/dead, MTT and colony-forming units (CFUs) assay. Furthermore, the effects on fibroblast growth and colour were test in this study. Results The data of the Novaron and control groups were analyzed by Student’s t-test. The results showed that the activities of S. mutans , F. nucleatum and C. albicans biofilms on the composites surface were greatly reduced ( p < 0.05) and no significant difference was found in the culture medium ( p > 0.05). Extracts taken from the cell culture medium of the specimens were used to evaluate cell viability. The composites did not have an adverse effect on fibroblast growth and colour in this study. The results showed that 4 wt% Novaron incorporated into the resin composites could increase the surface hardness ( p < 0.05). Therefore, Novaron is a potential antimicrobial agent applying in light-cured and inorganic nanoparticles reinforced dental resin materials.
Three commercially-available conductive filaments were evaluated for 3D printing flexible circuits on paper. While all three filaments were printed successfully, the resulting conductive traces were found to have significantly different impedances when characterized by electrochemical impedance spectroscopy. Using a graphite-doped polylactic acid filament, the flexibility of paper-based conductive traces was evaluated, methods of integrating common electrical and electronic components with the conductive traces were demonstrated, and the resistive heating of the traces was characterized. The ability to 3D print conductive traces on paper using commercially available materials opens many opportunities for rapid prototyping of flexible electronics and for integrating electronic circuits with paper-based microfluidic devices.
The COVID-19 pandemic caused by SARS-CoV-2 has become a global public health concern. Recently, vaccines have been developed to treat this infectious disease. However, these newly developed vaccines are not widely available and not suitable for all age groups. In such circumstances, it is wise to wear personal protective equipment (PPE) such as masks, gloves, and gowns to better protect against COVID-19. Face masks have long been recommended as a means of preventing respiratory infections. However, inappropriate use of masks may undermine their effectiveness. The antimicrobial and antiviral properties of graphene have sparked interest in the development of medical devices such as face masks, gloves, and gowns with extra filtering ability to curb the effects of the coronaviruses. Their hydrophobicity, nanosize, large surface area, high electrical and thermal conductivities, and virulence are notable features that reduce the transmission of viruses from person to person via respiratory routes. Graphene-enhanced face masks are intended to encourage travelers to wear them at work and during recreational activities. Moreover, graphene can pose health hazards if inhaled during respiration. In this review, we summarize the current status of graphene and its promising applications for combating COVID-19. Additionally, this review aims to explore the quality of this biomaterial and possible suggestions for the better and safer use of graphene structured respirators.
