DLP Fabrication of Zirconia Scaffolds Coated with HA/β-TCP Layer: Role of Scaffold Architecture on Mechanical and Biological Properties

In order to merge high-mechanical properties and suitable bioactivity in a single scaffold, zirconia porous structures are here coated with a hydroxyapatite layer. The digital light processing (DLP) technique is used to fabricate two types of scaffolds: simple lattice structures, with different sizes between struts (750, 900 and 1050 µm), and more complex trabecular ones, these latter designed to better mimic the bone structure. Mechanical tests performed on samples sintered at 1400 °C provided a linear trend with a decrease in the compressive strength by increasing the porosity amount, achieving compressive strengths ranging between 128-177 MPa for lattice scaffolds and 34 MPa for trabecular ones. Scaffolds were successfully coated by dipping the sintered samples in a hydroxyapatite (HA) alcoholic suspension, after optimizing the HA solid loading at 20 wt%. After calcination at 1300 °C, the coating layer, composed of a mixture of HA and beta-TCP (beta-TriCalcium Phospate) adhered well to the zirconia substrate. The coated samples showed a proper bioactivity, well pronounced after 14 days of immersion into simulated body fluid (SBF), with a more homogeneous apatite layer formation into the trabecular samples compared to the lattice ones

Environmentally-Friendly Dense and Porous Geopolymers Using Fly Ash and Rice Husk Ash as Raw Materials

This paper assesses the feasibility of two industrial wastes, fly ash (FA) and rice husk ash (RHA), as raw materials for the production of geopolymeric pastes. Three typologies of samples were thus produced: (i) halloysite activated with potassium hydroxide and nanosilica, used as the reference sample (HL-S); (ii) halloysite activated with rice husk ash dissolved into KOH solution (HL-R); (iii) FA activated with the alkaline solution realized with the rice husk ash (FA-R). Dense and porous samples were produced and characterized in terms of mechanical properties and environmental impact. The flexural and compressive strength of HL-R reached about 9 and 43 MPa, respectively. On the contrary, the compressive strength of FA-R is significantly lower than the HL-R one, in spite of a comparable flexural strength being reached. However, when porous samples are concerned, FA-R shows comparable or even higher strength than HL-R. Thus, the current results show that RHA is a valuable alternative to silica nanopowder to prepare the activator solution, to be used either with calcined clay and fly ash feedstock materials. Finally, a preliminary evaluation of the global warming potential (GWP) was performed for the three investigated formulations. With the mix containing FA and RHA-based silica solution, a reduction of about 90% of GWP was achieved with respect to the values obtained for the reference formulatio

WO3-Doped Indium Oxide Thick Films for Ozone Detection at Low Temperature

Ozone, a strong oxidizing gas, has dramatically increased its concentration in the troposphere during the last decades. Since high O3 concentrations are hazardous to human health, the development of effective methods and economic devices to detect this gas is an urgent need. In this frame, In2O3 is well known as an n-type ozone sensitive and selective material, generally displaying its optimal sensing capability in the temperature range 200–350 °C. To enhance the sensing capability of In2O3 and to decrease its operative temperature, in this work, commercial In2O3 powders were doped with 2.5 wt. % WO3. Pure and doped-In2O3 materials were used to develop sensing devices by screen-printing technology. Resistance measurements were performed in the temperature range 25 °C–150 °C under 200–500 ppb O3. Best results were obtained at 75 °C with sensor’s responses as high as 40 under 200 ppb of ozone

Alkali activation of waste materials: sustainability and innovation in processing traditional ceramics

Environmental issues linked both to OPC production and waste management brought researchers to find new solutionsfor the production of more eco-efficient binders. In this frame, alkali-activated materials are receiving increasing attention. They are obtained by reaction of an alkali metal source, generally sodium or potassium, with amorphous calcium-aluminosilicate precursors. More recently, also the reuse of mining wastes was investigated due to the impressive production of sludges and muds which do not have practical applications and shall be landfilled. The aim of our researches was to investigate the use of semi-crystalline/high-crystalline by-products in the production of alkali-activated materials. Thus, two different powders were used: an alumino silicate mud, composed by quartz, feldspars, biotite and dolomite; and a carbonatic one, composed of calcite and small amounts of dolomite. Both powders were alkali-activated using a solution of NaOH and Na2SiO3. Pastes were produced mixing the activating solution and the powder in different liquid/solid ratiosandinvestigatingthe use of waste glass powder as further source of amorphous silica. Samples were oven-cured for 24h at 60-80 °C and then cured in different environments (dry, humid and immersed in water) for other 27 days before testing physical and mechanical properties. Very promising results were obtained in terms of compressive strength (about 30 MPa for the aluminosilicate sludge and up to 45 MPa for the carbonatic one), showing their potential as innovative building products

Vat-photopolymerization of ceramic materials: exploring current applications in advanced multidisciplinary fields

Additive manufacturing has brought about a real revolution in the manufacture of objects in a variety of application areas, overturning the traditional paradigm based on subtractive approaches. The potential benefits deriving from the application of these techniques in the field of ceramic materials extend to different industrial sectors, leading to shorter, more accurate and cost-effective manufacturing processes. Within the present review, we provide a transversal analysis of the state-of-the-art of the applications of vat-photopolymerization technologies, namely, stereolithography and digital light processing in relevant technological industrial/research fields of our times, including biomedicine, energy, environment, space and aerospace, with a special focus on current trends and project-specific requirements. Unmet challenges and future developments will be discussed as well, providing readers a transfer of knowledge and “lessons learned” from one field to the other, being this approach aimed at the further growth of the technology towards its industrialization and market uptake

“Materiale edilizio ottenuto da attivazione alcalina di minerali contenuti in prodotti e residui da attività estrattiva e lavorativa e processo di produzione di un tale materiale edilizio"

L'invenzione si riferisce a un materiale edilizio ottenuto da attivazione alcalina di minerali contenuti in prodotti e residui da attività estrattiva e lavorativa. La presente invenzione si riferisce altresì a un processo di produzione di tale materiale edilizio. In particolare, la presente invenzione si riferisce ai minerali presenti nei fanghi provenienti dal taglio di materiali lapidei ricchi di silicati o dall’impiego di altri prodotti di lavorazione ed estrazione da cava, quali ad esempio le cosiddette materie prime secondarie “MPS” costituite da scarti di lavorazione delle materie prime o dal recupero e dal riciclaggio dei rifiuti

Effects of Bifidobacterium longum Subsp. infantis CECT 7210 and Lactobacillus rhamnosus HN001, Combined or Not With Oligofructose-Enriched Inulin, on Weaned Pigs Orally Challenged With Salmonella Typhimurium

Salmonella is a common causative agent of enteric disease and is developing mechanisms of resistance to antimicrobials. Probiotics, such as bifidobacteria and lactobacilli, and prebiotic fibers are a potential alternative to counteract this pathogen as they have demonstrated effectiveness in preventing its adhesion, reducing intestinal damage, and enhancing the host immune system. Furthermore, the benefits are expected to be potentiated when these compounds are administered together. A trial was performed to evaluate the efficacy of two probiotic strains (Bifidobacterium longum subsp. infantis CECT 7210 (Laboratorios Ordesa S.L.) and Lactobacillus rhamnosus HN001, combined or not with a prebiotic containing oligofructose-enriched inulin, against Salmonella Typhimurium. Ninety-six piglets (28 days old) were distributed into 32 pens assigned to 5 treatments: one non-challenged (control diet, CTR+) and four challenged: control diet (CTR−) or supplemented with probiotics (>3 × 10 10 cfu/kg each strain, PRO), prebiotic (5%, PRE), or their combination (SYN). After 1 week of adaptation, animals were orally challenged with Salmonella Typhimurium. Feed intake, weight, and clinical signs were recorded. On days 4 and 8 post-inoculation (PI), one animal per pen was euthanized, and samples from blood, digestive content, and ileal tissues were collected to determine Salmonella counts, fermentation products, ileal histomorphology, and serum TNF-α and Pig-MAP concentrations. The effect of the oral challenge was evidenced by animal performance, fecal consistency, and intestinal architecture. Regarding the experimental treatments, animals belonging to the PRO group experienced a faster clearance of the pathogen, with more pigs being negative to its excretion at the end of the study and recovering the impaired ileal villi/crypt ratio more rapidly. Animals receiving the PRE diet showed a lower intestinal colonization by Salmonella, with no countable levels (<3 cfu/g) in any of the analyzed samples, and an augmented immune response suggested by serum Pig-MAP concentrations. Treatments including the prebiotic (PRE and SYN) showed similar changes in the fermentation pattern, with an increase in the molar percentage of valeric acid concentration in the colon. The SYN group, however, did not show any of the outcomes registered for PRO and PRE in Salmonella colonization or in immunity markers, suggesting the lack of synbiotic action in this animal model. Further research is needed to better understand the complex mechanisms behind these effects