High-porosity metakaolin-based geopolymer foams (GFs) were fabricated by a gelcasting technique using hydrogen peroxide (foaming agent) in combination with Tween 80 (surfactant). Slurries processed ...in optimized conditions enabled to fabricate potassium based GFs with a total porosity in the range of ∼67 to ∼86 vol% (∼62 to ∼84 vol% open), thermal conductivity from ∼0.289 to ∼0.091 W/mK, and possessing a compressive strength from ∼0.3 to ∼9.4 MPa. Moreover, factors that influence the compressive strength, the porosity, the thermal conductivity, and the cell size distribution were investigated. The results showed that the cell size and size distribution can be controlled by adding different content of surfactant and foaming agent. The foamed geopolymer can also be used as adsorbents for the removal of copper and ammonium ions from wastewater. The foams, due to their low thermal conductivity, could also be used for thermal insulation. It was also possible to produce geopolymer formulations that could be printed using additive manufacturing technology (Direct Ink writing), which enabled to produce components with nonstochastic porosity.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this work, the possibility of shaping a glass-filled photosensitive polymer resin with Digital Light Processing (DLP) into a complex 3D structure and transforming it subsequently into a bioactive ...glass-ceramic scaffold was investigated. The influence of the printing conditions and the heat-treatment was studied using a 41 vol% glass-filled acrylated polymer resin. Scaffolds with designed architecture were turned into a wollastonite-diopside glass-ceramic at 1100 °C. They completely maintained their shape, exhibited no viscous flow and showed a homogenous linear shrinkage of around 25%. At 83 vol% porosity structures with Kelvin cell design exhibited a compressive strength exceeding 3 MPa, demonstrating that the material is suitable for the fabrication of bioceramic scaffolds for bone tissue engineering applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The overall success and long-term life of the medical implants are decisively based on the convenient osseointegration at the hosting tissue-implant interface. Therefore, various surface ...modifications and different coating approaches have been utilized to the implants to enhance the bone formation and speed up the interaction with the surrounding hosting tissues, thereby enabling the successful fixation of implants. In this review, we will briefly present the main metallic implants and discuss their biocompatibility and osseointegration ability depending on their chemical and mechanical properties. In addition, as the main goal of this review, we explore the main properties of bioactive glasses and silica-based ceramics that are used as coating materials for both orthopedic and dental implants. The current review provides an overview of these bioactive coatings, with a particular emphasis on deposition methods, coating adhesion to the substrates and apatite formation ability tested by immersion in Simulated Body Fluid (SBF).
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performances in terms of biocompatibility, biodegradability and improved osseointegration are examined as well.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Allowing for complex shape and low energy consumption, 3D printing, debinding, and sintering (PDS) is a promising and cost-effective additive manufacturing (AM) technology. Moreover, PDS is ...particularly suitable for producing bimetallic parts using two metal/polymer composite filaments in the same nozzle, known as co-extrusion, or in different nozzles, in a setup called bi-extrusion. The paper describes a first attempt to produce bimetallic parts using Inconel 718 and AISI 316L stainless steel via PDS. The primary goal is to assess the metallurgical characteristics, part shrinkage, relative density, and the interdiffusion phenomenon occurring at the interface of the two alloys. A first set of experiments was conducted to investigate the effect of deposition patterns on the above-mentioned features while keeping the same binding and sintering heat treatment. Different sintering temperatures (1260 °C, 1300 °C, and 1350 °C) and holding times (4 h and 8 h) were then investigated to improve the density of the printed parts. Co-extruded parts showed a better dimensional stability against the variations induced by the binding and sintering heat treatment, compared to bi-extruded samples. In co-extruded parts, shrinkage depends on scanning strategy; moreover, the higher the temperature and holding time of the sintering heat treatment, the higher the density reached. The work expands the knowledge of PDS for metallic multi-materials, opening new possibilities for designing and utilizing functionally graded materials in optimized components. With the ability to create intricate geometries and lightweight structures, PDS enables energy savings across industries, such as the aerospace and automotive industries, by reducing component weight and enhancing fuel efficiency. Furthermore, PDS offers substantial advantages in terms of resource efficiency, waste reduction, and energy consumption compared to other metal AM technologies, thereby reducing environmental impact.
Wollastonite (CaSiO3)–diopside (CaMgSi2O6) glass-ceramic scaffolds have been successfully fabricated using two different additive manufacturing techniques: powder-based 3D printing (3DP) and digital ...light processing (DLP), coupled with the sinter-crystallization of glass powders with two different compositions. The adopted manufacturing process depended on the balance between viscous flow sintering and crystallization of the glass particles, in turn influenced by the powder size and the sensitivity of CaO–MgO–SiO2 glasses to surface nucleation. 3DP used coarser glass powders and was more appropriate for low temperature firing (800–900 °C), leading to samples with limited crystallization. On the contrary, DLP used finer glass powders, leading to highly crystallized glass-ceramic samples. Despite the differences in manufacturing technology and crystallization, all samples featured very good strength-to-density ratios, which benefit their use for bone tissue engineering applications. The bioactivity of 3D-printed glass-ceramics after immersion in simulated body fluid and the similarities, in terms of ionic releases and hydroxyapatite formation with already validated bioactive glass-ceramics, were preliminarily assessed.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Alkali-activated materials are gaining much interest due to their outstanding performance, including their great resistance to chemical corrosion, good thermal characteristics, and ability to ...valorise industrial waste materials. Reusing waste glasses in creating alkali-activated materials appears to be a viable option for more effective solid waste utilisation and lower-cost products. However, very little research has been conducted on the suitability of waste glass as a prime precursor for alkali activation. This study examines the reuse of seven different types of waste glasses in the creation of geopolymeric and cementitious concretes as sustainable building materials, focusing in particular on how using waste glasses as the raw material in alkali-activated materials affects the durability, microstructures, hydration products, and fresh and hardened properties in comparison with using traditional raw materials. The impacts of several vital parameters, including the employment of a chemical activator, gel formation, post-fabrication curing procedures, and the distribution of source materials, are carefully considered. This review will offer insight into an in-depth understanding of the manufacturing and performance in promising applications of alkali-activated waste glass in light of future uses. The current study aims to provide a contemporary review of the chemical and structural properties of glasses and the state of research on the utilisation of waste glasses in the creation of alkali-activated materials.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
To combat insect pests and vectors that are responsible for high losses in food and lives, insecticide discovery is of top priority. This study aimed to synthesize, characterize and investigate the ...insecticidal activity of 1,3,4-oxadiazole derivatives grafted on chitosan (CS) and modified polymethyl methacrylate (PMMA). 5-(pyridin-3-yl)-1,3,4-oxadiazole-2-thiol and 5-(pyridin-4-yl)-1,3,4-oxadiazole-2-thiol were respectively reacted with ethylchloroacetate and methyl-2-choloroacetoacetate. The resulted esters were grafted with CS and modified-PMMA. The products were characterized using FT-IR, 1H NMR, TGA, and XRD techniques. Four CS grafted ones were able to show good insecticidal activity against the cotton leafworm Spodoptera littoralis. Furthermore, the safety of these compounds was tested using MTT assay on a human cell line (WI-38). The results indicated that compounds 2a, 2b, 6a, and 6d are considered insecticide candidates to S. littoralis fourth-instar larvae. Cytotoxicity of 2b and 6d indicated that they are the least toxic to humans. It is concluded that both compounds may represent promising insecticide candidates.
•Insecticide discovery is now of top priority.•Spodoptera littorlais is a prime candidate for pests in Africa and Europe.•Oxadiazole derivatives have insecticidal capacity against the cotton leafworm.•Compounds CS-S-oxadiazole and CS-Chloroester-S-oxadiazole are good candidates as insecticide for controlling S. littoralis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Monolithic and powdered Biosilicate®, produced by conventional glass‐ceramic technology, have been widely recognized as excellent materials for bone tissue engineering applications. In the current ...research, we focus on an alternative processing route for this material, consisting of the thermal treatment of silicone polymers containing micro‐sized oxide fillers, which offers a unique integration between materials synthesis and shaping. In particular, the new method allows obtaining highly porous Biosilicate® glass‐ceramics, in the form of 3D printed scaffolds and foams. 3D scaffolds were successfully fabricated by direct writing using an ink based on a silicone polymer and active inorganic fillers, followed by firing in air at 1000°C. The products showed regular geometries, large open porosity (~60 vol%) and still high compressive strength (~7 MPa). Open‐cellular foams with porosity up to ∼80 vol% were also prepared from liquid silicones mixed with several fillers, including hydrated sodium phosphate. This specific filler acted both as a foaming agent, because of the gas release by dehydration occurring at low temperature, and as a provider of liquid phase upon firing in air, again at 1000°C.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Pastes based on preceramic polymers have a great potential for direct ink writing of bioceramic scaffolds. In this paper, we discuss the fabrication of phase pure sphene (CaTiSiO5) bioceramics, ...developed by firing, at 1300°C, of silicone‐based printed scaffolds containing CaCO3 and TiO2 as active fillers. As a proof of the flexibility of the combination of preceramic polymers and additive manufacturing technologies, several lattice geometries of increasing complexity were successfully explored. In particular, the approach allowed the fabrication of sphene scaffolds with gyroid‐like structure exhibiting an impressive compressive strength, given the high porosity. Moreover, different lattice topologies of sphene scaffolds were compared also in terms of permeability.
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Direct-Ink-Writing (or robocasting) is a subset of extrusion-based additive manufacturing techniques that has grown significantly in recent years to design simple to complex ceramic structures. ...Robocasting, relies on the use of high-concentration powder pastes, also known as inks. A successful optimization of ink rheology and formulation constitutes the major key factor to ensure printability for the fabrication of self-supporting ceramic structures with a very precise dimensional resolution. However, to date achieving a real balance between a comprehensive optimization of ink rheology and the determination of a relevant protocol to predict the printing parameters for a given ink is still relatively scarce and has been not yet standardized in the literature.
The current review reports, in its first part, a detailed survey of recent studies on how ink constituents and composition affect the direct-ink-writing of ceramic parts, taking into account innovative ceramic-based-inks formulations and processing techniques. Precisely, the review elaborates the major factors influencing on ink rheology and printability, specifically binder type, particle physical features (size, morphology and density) and ceramic feedstock content.
In the second part, this review suggests a standardized guideline to effectively adapt a suitable setting of the printing parameters, such as printing speed and pressure, printing substrate, strut spacing, layer height, nozzle diameter in function of ink intrinsic rheology.
Robocasting; Glass; Ceramics; Feedstock features; Printing parameters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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