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An epoxy resin was nanomodified with in-situ generated silver nanoparticles (Ag) and with various amounts of carbon black (CB) and carbon nanofibers (NF), in order to increase the electrical conductivity of the matrix. Differential scanning calorimetry tests revealed how the addition of both CB and NF led to a slight decrease of the glass transition temperature of the material, while electron microscopy evidenced how the dimension of CB aggregates increased with the filler content. Both flexural modulus and stress at yield were decreased by CB addition, and the introduction of Ag nanoparticles promoted an interesting improvement of the flexural resistance. CB resulted to be more effective than NF in decreasing the electrical resistance of the materials down to 103 Ω•cm. Therefore, a rapid heating of the CB-filled samples upon voltage application was observed, while Ag nanoparticles allowed a stabilization of the temperature for elevated voltage application times.

The Powder Bed Fusion-Laser Beam/Metals (PBF-LB/M) is a promising additive manufacturing process that can be used to directly produce functional components with a complex shape for a wide variety of applications. However, the layer-by-layer scanning and high cooling rates result in a high thermal gradient and thus, in thermally induced stresses. The stresses developed during the additive process could lead to undesirable cracking and delamination phenomena that can seriously affect the performance of the final component. The alloy composition can exacerbate crack and delamination formation, however, the need to expand the portfolio of high-strength materials processable for PBF-LB/M makes the resolution of these undesirable phenomena a primary challenge in the additive manufacturing field. This works aims to systematically investigate some strategies to make processable non-standard compositions. As no standard compositions, the promising pre-alloyed AlSi10Cu8Mg composition was chosen for the present work. Based on the results obtained from a condition of severe delamination, the synergetic use of appropriate process parameters and support structures can lead to crack-free and fully dense specimens also when platform heating is not allowed. The developed approach could also be applied to adapt other cracking-sensitive alloys for PBF-LB/M production.

The present work aimed to prepare novel bio-based composites by adding fillers coming from agro-wastes to an acrylate epoxidized soybean oil (AESO) resin, using liquid crystal display (LCD) 3D printing. Different photocurable formulations were prepared by varying the reactive diluents, iso-bornyl methacrylate (IBOMA) and tetrahydrofurfuryl acrylate (THFA). Then, two fillers derived from different industrial wastes, corn (GTF) and wine (WPL-CF) by-products, were added to the AESO-based formulations to develop polymer composites with improved properties. The printability by LCD of the photocurable formulations was widely studied. Bio-based objects with different geometries were realized, showing printing accuracy, layer adhesion, and accurate details. The thermo-mechanical and mechanical properties of the 3D-printed composites were tested by TGA, DMA, and tensile tests. The results revealed that the agro-wastes' addition led to a remarkable increase in the elastic modulus, tensile strength, and glass transition temperature in the glassy state for the systems containing IBOMA and for flexible structures in the rubbery region for systems containing THFA. AESO-based polymers demonstrated tunable properties, varying from rigid to flexible, in the presence of different diluents and biofillers. This finding paves the way for the use of this kind of composite in applications, such as biomedical for the realization of prostheses.

This current study investigates the effect of Direct Energy Deposition (DED) process conditions on the properties and microstructure of M300 maraging steel samples. The investigation centers on two key factors: laser power and deposition environment. The microstructure of this tool steel is analyzed by computing the Primary Cellular Arm Spacing. The findings revealed a significant influence of both inert atmosphere and laser power on cooling conditions. These different cooling rates influence the phase content as demonstrated by X-Ray Diffraction and Electron Backscatter Diffraction measurements. It was demonstrated the presence of different content of residual austenite at cell boundaries. These distinct microstructural features caused variations in the hardness values of the printed samples. Furthermore, a direct aging heat treatment was implemented, that was chosen from Differential Scanning Calorimetry measurements results. This heat treatment proves effective in achieving consistent hardness increases and eliminated the differences among samples built in different process conditions. This outcome suggests the possibility of selecting the most economically viable DED parameters for optimal results., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2024 The Author(s). Published by National Institute for Materials Science in partnership with Taylor & Francis Group.)

While biomaterials have become indispensable for a wide range of tissue repair strategies, second removal procedures oftentimes needed in the case of non-bio-based and non-bioresorbable scaffolds are associated with significant drawbacks not only for the patient, including the risk of infection, impaired healing, or tissue damage, but also for the healthcare system in terms of cost and resources. New biopolymers are increasingly being investigated in the field of tissue regeneration, but their widespread use is still hampered by limitations regarding mechanical, biological, and functional performance when compared to traditional materials. Therefore, a common strategy to tune and broaden the final properties of biopolymers is through the effect of different reinforcing agents. This research work focused on the fabrication and characterization of a bio-based and bioresorbable composite material obtained by compounding a poly(3-hydroxybutyrate- co -3-hydroxyhexanoate) (PHBH) matrix with acetylated cellulose nanocrystals (CNCs). The developed biocomposite was further processed to obtain three-dimensional scaffolds by additive manufacturing (AM). The 3D printability of the PHBH-CNC biocomposites was demonstrated by realizing different scaffold geometries, and the results of in vitro cell viability studies provided a clear indication of the cytocompatibility of the biocomposites. Moreover, the CNC content proved to be an important parameter in tuning the different functional properties of the scaffolds. It was demonstrated that the water affinity, surface roughness, and in vitro degradability rate of biocomposites increase with increasing CNC content. Therefore, this tailoring effect of CNC can expand the potential field of use of the PHBH biopolymer, making it an attractive candidate for a variety of tissue engineering applications.

This work focuses on the effect of different heat treatments on the Ti-6Al-4V alloy processed by means of electron beam melting (EBM). Super β-transus annealing was conducted at 1050 °C for 1 h on Ti-6Al-4V samples, considering two different cooling paths (furnace cooling and water quenching). This heat treatment induces microstructural recrystallization, thus reducing the anisotropy generated by the EBM process (columnar prior-β grains). Subsequently, the annealed furnace-cooled and water-quenched samples were aged at 540 °C for 4 h. The results showed the influence of the aging treatment on the microstructure and the mechanical properties of the annealed EBM-produced Ti-6Al-4V. A comparison with the traditional processed heat-treated material was also conducted. In the furnace-cooled specimens consisting of lamellar α+β, the aging treatment improved ductility and strength by inducing microstructural thickening of the α laths and reducing the β fraction. The effect of the aging treatment was also more marked in the water-quenched samples, characterized by high tensile strengths but limited ductility due to the presence of martensite. In fact, the aging treatment was effective in the recovery of the ductility loss, maintaining high tensile strength properties due to the variation in the relative number of α/α' interfaces resulting from α' decomposition. This study, therefore, offers an in-depth investigation of the potential beneficial effects of the aging treatment on the microstructure and mechanical properties of the EBM-processed super β-transus heat-treated Ti-6Al-4V alloy under different cooling conditions.

Among recently developed high-strength and lightweight alloys, the high-performance Scalmalloy ® certainly stands out for laser powder bed fusion (LPBF) production. The primary goal of this study was to optimize the Scalmalloy ® LPBF process parameters by setting power values suitable for the use of lab-scale machines. Despite that these LPBF machines are commonly characterized by considerably lower maximum power values (around 100 W) compared to industrial-scale machines (up to 480 W), they are widely used when quick setup and short processing time are needed and a limited amount of powder is available. In order to obtain the optimal process parameters, the influence of volumetric energy density (VED) on the sample porosity, microstructure and mechanical properties was accurately studied. The obtained results reveal the stability of the microstructural and mechanical behaviour of the alloy for VEDs higher than 175 Jmm -3 . In this way, an energy-and-time-saving choice at low VEDs can be taken for the LPBF production of Scalmalloy ® . After identifying the low-power optimized process parameters, the effects of the heat treatment on the microstructural and mechanical properties were investigated. The results prove that low-VED heat-treated samples produced with an LPBF lab-scale machine can achieve outstanding mechanical performance compared with the results of energy-intensive industrial production.

We characterize poly(3-hydroxybutyrate- co -3-hydroxyhexanoate) (PHBH) scaffolds for tissue repair and regeneration, manufactured by three-dimensional fused filament fabrication (FFF). PHBH belongs to the class of polyhydroxyalkanoates with interesting biodegradable and biocompatible capabilities, especially attractive for tissue engineering. Equally, FFF stands as a promising manufacturing technology for the production of custom-designed scaffolds. We address thermal, rheological and cytotoxicity properties of PHBH, placing special emphasis on the mechanical response of the printed material in a wide deformation range. Indeed, effective mechanical properties are assessed in both the linear and nonlinear regime. To warrant uniqueness of the material parameters, these are measured directly through digital image correlation, both in tension and compression, while experimental data fitting of finite-element analyses is only adopted for the determination of the second invariant coefficient in the nonlinear regime. Mechanical data are clearly porosity dependent, and they are given for both the cubic and the honeycomb infill pattern. Local strain spikes due to the presence of defects are observed and measured: those falling in the range 70-100% lead to macro-crack development and, ultimately, to failure. Results suggest the significant potential attached to FFF printing of PHBH for customizable medical devices which are biocompatible and mechanically resilient., Competing Interests: We declare we have no competing interests., (© 2022 The Authors.)

Conventionally processed precipitation hardening aluminum alloys are generally treated with T6 heat treatments which are time-consuming and generally optimized for conventionally processed microstructures. Alternatively, parts produced by laser powder bed fusion (L-PBF) are characterized by unique microstructures made of very fine and metastable phases. These peculiar features require specifically optimized heat treatments. This work evaluates the effects of a short T6 heat treatment on L-PBF AlSi7Mg samples. The samples underwent a solution step of 15 min at 540 °C followed by water quenching and subsequently by an artificial aging at 170 °C for 2-8 h. The heat treated samples were characterized from a microstructural and mechanical point of view and compared with both as-built and direct aging (DA) treated samples. The results show that a 15 min solution treatment at 540 °C allows the dissolution of the very fine phases obtained during the L-PBF process; the subsequent heat treatment at 170 °C for 6 h makes it possible to obtain slightly lower tensile properties compared to those of the standard T6. With respect to the DA samples, higher elongation was achieved. These results show that this heat treatment can be of great benefit for the industry.

The production of dense samples produced by laser powder bed fusion (LPBF) is mainly determined by the choice of the best combination of construction parameters. Parameter optimization is the first step in the definition of an LPBF process for new alloys or systems. With this goal, much research uses the single scan track (SST) approach for a preliminary parameter screening. This study investigates the definition of a computer-aided method by using an automatic on top analysis for the characterization of SSTs, with the aim of finding ranges of laser power and scan speed values for massive production. An innovative algorithm was implemented to discard non-continuous scans and to measure the SSTs quality using three regularity indexes. Only open source software were used to fine tune this approach. The obtained results on Al4Cu and AlSi10Mg realized with two different commercial systems suggest that it is possible to use this method to easily narrow the process parameter window that allows the production of dense samples.

In recent years, biopolymers have been attracting the attention of researchers and specialists from different fields, including biotechnology, material science, engineering, and medicine. The reason is the possibility of combining sustainability with scientific and technological progress. This is an extremely broad research topic, and a distinction has to be made among different classes and types of biopolymers. Polyhydroxyalkanoate (PHA) is a particular family of polyesters, synthetized by microorganisms under unbalanced growth conditions, making them both bio-based and biodegradable polymers with a thermoplastic behavior. Recently, PHAs were used more intensively in biomedical applications because of their tunable mechanical properties, cytocompatibility, adhesion for cells, and controllable biodegradability. Similarly, the 3D-printing technologies show increasing potential in this particular field of application, due to their advantages in tailor-made design, rapid prototyping, and manufacturing of complex structures. In this review, first, the synthesis and the production of PHAs are described, and different production techniques of medical implants are compared. Then, an overview is given on the most recent and relevant medical applications of PHA for drug delivery, vessel stenting, and tissue engineering. A special focus is reserved for the innovations brought by the introduction of additive manufacturing in this field, as compared to the traditional techniques. All of these advances are expected to have important scientific and commercial applications in the near future.

In this study bioactive and bioresorbable porous scaffolds for bone tissue regeneration, based on poly(3-hydroxybutyrate) (PHB), are presented. The porous structure is obtained by thermally induced phase separation (TIPS) technique, whereas the osteoinductivity and osteoconductivity are enhanced through the incorporation of hydroxyapatite (HA). The HA particles are generated in PHB using an innovative filler in situ synthesis, and the properties of the composite scaffolds are then compared to scaffolds obtained by conventional mechanical dispersion of ex situ synthesized HA particles. The in situ synthesis leads to composite materials with improved porosity, even at high filler content, without any degradation of the polymeric matrix as confirmed by GPC and DSC measurements. On the contrary, the samples prepared by ex situ method show a suppressed porosity by increasing the inorganic filler content, therefore limiting the amount of HA that can be loaded in PHB and the resulting bioactivity. The possibility to use PHB/HA porous composites as scaffolds for bone tissue regeneration, is assessed by preliminary cell viability in vitro studies. In particular, it is observed that the composites are fully cytocompatible and able to sustain MC3T3-E1 mouse pre-osteoblast cells adhesion and proliferation. Investigations on cell morphology reveal, for all PHB/HA scaffolds, the presence of differentiated cells with a predominance of osteocyte-like morphology, which are not observed for neat PHB scaffolds. Moreover, the MC3T3-E1 cells differentiation towards osteoblastic phenotype is further supported by the evaluation of the early osteogenic markers. In particular, samples loaded with HA in situ synthesized showed the highest ALP production and typical morphology of the terminal differentiation stages of osteoblasts., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The aim of this review is a faithful report of the panorama of solutions adopted to fabricate a component using vat photopolymerization (VP) processes. A general overview on additive manufacturing and on the different technologies available for polymers is given. A comparison between stereolithography and digital light processing is also presented, with attention to different aspects and to the advantages and limitations of both technologies. Afterward, a quick overview of the process parameters is given, with an emphasis on the necessities and the issues associated with the VP process. The materials are then explored, starting from base matrix materials to composites and nanocomposites, with attention to examples of applications and explanations of the main factors involved.

The limited availability of materials with special properties represents one of the main limitations to a wider application of polymer-based additive manufacturing technologies. Filled resins are usually not suitable for vat photo-polymerization techniques such as stereolithography (SLA) or digital light processing (DLP) due to a strong increment of viscosity derived from the presence of rigid particles within the reactive suspension. In the present paper, the possibility to in situ generate silver nanoparticles (AgNPs) starting from a homogeneous liquid system containing a well dispersed silver salt, which is subsequently reduced to metallic silver during stereolithographic process, is reported. The simultaneous photo-induced cross-linking of the acrylic resin produces a filled thermoset resin with thermal-mechanical properties significantly enhanced with respect to the unfilled resin, even at very low AgNPs concentrations. With this approach, the use of silver salts having carbon-carbon double bonds, such as silver acrylate and silver methacrylate, allows the formation of a nanocomposite structure in which the release of by-products is minimized due to the active role of all the reactive components in the three dimensional (3D)-printing processes. The synergy, between this nano-technology and the geometrical freedom offered by SLA, could open up a wide spectrum of potential applications for such a material, for example in the field of food packaging and medical and healthcare sectors, considering the well-known antimicrobial effects of silver nanoparticles., Competing Interests: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.

Recently, there has been a rise in the interest in nanotechnology due to its enormous potential for the development of new products and applications with higher performance and new functionalities. However, while nanotechnology might revolutionize a number of industrial and consumer sectors, there are uncertainties and knowledge gaps regarding toxicological effects of this emerging science. The goal of this research concerns the implementation into Life Cycle Assessment (LCA) of preliminary frameworks developed to evaluate human toxicity and exposure factors related to the potential nanoparticle releases that could occur during the life cycle steps of a functionalized building material. The present LCA case study examines the ecodesign of nanoTiO 2 functionalized porcelain stoneware tile production. The aim of this investigation is to manufacture new eco-friendly products in order to protect human health and ecosystem quality and to offer the market, materials with higher technological properties obtained by the addition of specific nanomaterials., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Introduction: The aim of the present work was to analyze the possibility of creating a light-storing photocatalyst material, a system that couples a phosphorescent substrate with a titania coating. The substrate could activate the titanium dioxide coating even in condition of darkness thanks to its light emission. This improvement of absorption can be achieved because the titania semiconductor is irradiated both by the direct light and by the luminescent substrate which is activated at the same time., Methods: TiO2-based sol-gel solutions were deposited on commercial borosilicate glasses containing 2 different phosphorescent pigments (emission peaks at 470 and 520 nm, respectively). Particular attention was paid to optimize the film-substrate adhesion by using a scratch test to evaluate the optimal temperature of the post- treatment step., Results and Discussion: The main result is that when irradiated the photoluminescent pigments allow an increase in the photocatalytic acitivity of the coatings. The pigments are able to convert the ultraviolet component of light in order to increase the amount of energy that can be absorbed by titania. Moreover, the hydrophilicity test showed that in the absence of irradiation the phosphorescent samples are characterized by a lower loss of superhydrophilicity.

The dynamics of the early stage reaction between benzyl alcohol and Fe(acetylacetonate)3 is studied by exploiting the Dynamic Reaction Coordinate (DRC) approach, at the PBE0/6-31G* level of theory. Analysis of the DRC trajectory provides a detailed molecular insight into the catalytic effect observed in the acidic reaction environment, compared to the neutral one. The presence of an additional proton in the reaction system, meant to simulate an acidic reaction environment, dramatically affects the reaction path: both by decreasing the activation energy of the complex dissociation and leading to the formation of acetone.

Polycaprolactone/hydroxyapatite (PCL/HA) composites were prepared by in situ generation of HA in the polymer solution starting from the precursors calcium nitrate tetrahydrate and ammonium dihydrogen phosphate via sol-gel process. Highly interconnected porosity was achieved by means of the salt-leaching technique using a mixture of sodium chloride and sodium bicarbonate as porogens. Structure and morphology of the PCL/HA composites were investigated by scanning electron microscopy, and mechanical properties were determined by means of tensile and compression tests. The possibility to employ the developed composites as scaffolds for bone tissue regeneration was assessed by cytotoxicity test of the PCL/HA composites extracts and cell adhesion and proliferation in vitro studies.

The aim of this investigation was the surface functionalization of industrial ceramic tiles by sol-gel technique to improve at the same time the cleanability of unglazed surfaces. This objective was pursued through the design and preparation of nanostructured coating that was deposited on polished unglazed tiles by air-brushing. In particular TiO(2)-SiO(2) binary film with 1, 2 or 5wt% of titania were prepared by using tetraethoxysilane and titania nanoparticles as precursors. The obtained films were characterized by scratch tests to verify the adhesion of the coatings to the polished tiles. To mainly evaluate the effect of the thermal treatment (temperature range 100-600 degrees C) on the photocatalicity of the coatings, the films were studied under UV exposure by contact angle measurements and cleanability test. Particular attention has been paid to preserve the aesthetical aspect of the final product and the obtained hue variation was evaluated by means of UV-visible spectroscopy and colorimetric analysis.

In this work the screening results of the scientific activity conducted on laboratory scale to valorise chromium(III) contained in the galvanic sludge as chromium precursor for ceramic pigments are reported. The valorisation of this waste as a secondary raw material (SRM) is obtained by achievement of thermal and chemical stable crystal structures able to color ceramic material. Two different pigments pink CaCr(0.04)Sn(0.97)SiO(5) and green Ca(3)Cr(2)(SiO(4))(3) were synthesized by solid-state reactions using dried Cr sludge as chromium oxide precursor. The obtained pigments were characterized by X-ray diffraction and SEM analysis. Furthermore the color developed in a suitable ceramic glaze was investigated in comparison with the color developed by the pigments prepared from pure Cr(2)O(3). The characterization carried out corroborates the thermal and chemical stability of the synthesized pigments and, especially for the Cr-Sn pink pigment, the powders develop an intense color that is very similar to the color developed by the pigments obtained starting from pure Cr(2)O(3).

In this research, after tracing a history of the pigment, the preparation and analysis of samples of Egyptian blue have been reported. The main reactions taking place during its preparation are indicated. X-ray diffractions show that, starting from mixtures of precursors with stoichiometric composition, the product is practically only cuprorivaite. The kind of flux and cristallinity of silica does not seem determining factors for the pigment formation. Infrared and Raman spectra and an assignment of the bands are reported. Impurities ascertained are discussed on the basis on the data available.