Pore evolution and compaction behaviour of spray-dried bodies for porcelain stoneware slabs

The compaction behavior of spray-dried powders has turned into concern in porcelain stoneware manufacturing due to the increasing diffusion of large slabs. It is necessary to fill a knowledge gap between the compaction behavior with conventional presses and novel technologies. For this purpose, eighteen industrially-manufactured spray dried bodies were characterized for specific properties connected to the compaction behavior (curves of bulk density, intergranular and intragranular porosity in function of applied load, apparent yield strength). In addition, the firing behavior was investigated in order to reveal any effect of dry bulk density on firing shrinkage and bulk density of fired samples. Powder compressibility is within 50% and 55% (Carr index) and is primarily controlled by moisture. Two regimes are found: low pressure (fast density increasing by granule cave in and closure of intergranular porosity) and high pressure (slow density gain by downsizing microporosity). A peculiar mechanism is unveiled: granules squeeze in the low-P regime and further densification is achieved through microfracture around individual agglomerate. A phenomenological model is illustrated for the compaction of spray-dried powders. In conclusion, the performance of spray dried bodies during compaction is crucial to control the uniformity, in terms of porosity and bulk density, which has important repercussions on the properties of final slabs, especially differential shrinkages and deformation during firing due to density gradients.     

Processing and properties of polypropylene‐based composites containing inertized fly ash from municipal solid waste incineration

This article reports for the first time the results about the use of inertized fly ash from municipal solid waste incineration as a filler for polypropylene (PP). An innovative process based on the stabilization with colloidal silica has been used for fly ash inertization. Polymer–filler composites containing different filler amounts up to 30 wt % have then been formulated and prepared by means of melt compounding process. Structural, morphological, mechanical, and thermal characterization of their properties has been performed and discussed in detail. Remarkable enhancements of tensile (+ 93%) and flexural (+ 107%) elastic moduli if compared to pristine PP, together with enhancements of flexural resistance (+ 36%) and deflection temperature under load (+ 50%), have been observed when adding filler 30 wt % in suitable processing conditions. Moreover the filler has been shown to interact with polymer crystalline structure and positively influence the thermal‐oxidative stability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4157–4164, 2013     

Interactions of Cr(VI) and Cr(III) with isolated rat liver mitochondria

The mechanism of interaction of Cr(VI) with isolated rat liver mitochondria was investigated in this study. The results suggest that Cr(VI) induces the opening of the membrane permeability transition pore (MPT). The phenomenon is cyclosporine-sensitive and is in agreement with the cyclosporine-sensitive apoptosis observed in the cells incubated with this compound. Moreover the action of Cr(III), that is formed in the cells by a reduction of Cr(VI), has been also analysed. The results obtained demonstrated that the Cr(III) does not induce the opening of the MPT in isolated mitochondria, but it has a protective effect in preventing Cr(VI) MPT opening. Therefore, these results suggest that apoptosis is regulated by a balance between Cr(VI) accumulation in the cytoplasm and Cr(III) formation.     

Detoxification of olive mill wastewaters by zinc–aluminium layered double hydroxides

Disposal of olive mill waste waters (OMWW) represents a serious problem due to its elevated toxicity and pollution risk for environmental and aquatic bodies, which is mainly related to its polyphenol content. The use of layered double hydroxides (LDHs) or anionic clays for OMWW detoxification may represent an effective remediation process. In the current study, OMWW was treated with cold methanol to obtain a dark humic acid-like precipitate made of high molecular weight organic compounds named polymerin and a supernatant made of low molecular weight organics named OMWW-S. After precipitation with methanol, phenol content decreased from 2.14 g L^?1 to 0.80 and 1.20 g L^?1, in polymerin and OMWW-S, respectively. The chemical oxygen demand of OMWW-S decreased by about 30% with respect to raw OMWW, from 62.2 to 40.2 g L^?1. A phenolic concentrate, named OMWW-E was also obtained by ethyl acetate extraction of OMWW-S at pH 2.0. LDHs of zinc and aluminium (LDH) were obtained at room temperature and after calcination at 450 °C (LDH-450). An organo-mineral complex of LDH with polymerin (LDH-Pol) was also synthesised. Phenols from OMWW-E were sorbed preferentially on three matrices according to the following order: LDH-450 > LDH > LDH-Pol, with percent sorption of up to 73% for LDH-450. Repeated cycles of sorption of OMWW-S onto LDH-450 decreased phenol concentration by about 90%. Use of remediated water in a phytotoxicity bioassay revealed scant inhibition of germination and coleoptile elongation rate in tomato seeds and seedlings. Thus, OMWW-S after sorption onto LDH-450 could represent a low cost source of irrigation water for arid soil of the Mediterranean region.     

89Sr-doped hydroxyapatite nanoparticles as a potential therapeutic agent for bone tumors

Hydroxyapatite (HA) nanoparticles have been studied due to their high biocompatibility, similarity with bone tissue, and their capacity for bone regeneration since these nanoparticles can easily adhere on osteosarcoma and osteoblast cells, promoting osteoblast growth and osteosarcoma cell uptake. These materials may still accumulate spontaneously and selectively in regions of bone tumors through the enhanced permeability and retention effect. HA also allows the incorporation of strontium in your network. Strontium as a biochemical analog of calcium can maintain the osteogenesis characteristics of HA allowing the production of the radioactive isotopes strontium-89 and phosphorus-32 through neutron irradiation. These radioisotopes are beta emitters that enable the treatment of bone tumors, while the affected region is regenerated. In this work, we investigated the synthesis of strontium-doped HA nanorods through the hydrothermal coprecipitation method as a potential therapeutic agent for bone tumors. All materials were successfully obtained and demonstrated high cell viability, maintaining the osteogenic capacity, making these materials promising agents for the specific treatment of bone tumors. The results indicate that the Sr provides an increase in therapeutic potential due to its beta emission.     

Manufacturing and properties of biomimetic graphite nanoplatelets foils

Among the various architectures developed for composite materials, nanolaminated architecture is a promising candidate for the design of new materials for structural and functional applications. Nanolaminates mimic the natural occurring architecture of nacre and it is formed by highly oriented nanolaminae connected by a very low amount of matrix. Due to their architecture, inherently impermeable to fluid, such kind of materials is difficult to manufacture unless using layer‐by‐layer processes. Here, we describe the fabrication of films with nanolaminated architecture containing very high content (>80% w/w) of graphite nanoplatelets (GNPs) within an uncured epoxy matrix (prepregs), suitable for the conventional prepregs manufacturing technologies: film stacking and consolidation under temperature under pressure. Nanolaminated prepregs have been manufactured through the deposition of a paste of GNPs in epoxy enriched acetone solvent. Mainly, scanning electron microscopy has investigated the nanolaminated architecture of the prepregs. Stress–strain behavior of nanolaminated prepregs has been investigated as a function of their composition and consolidation pressure. Finally, a laminate made of six nanolaminated prepregs (about 0.3 mm thick) has been manufactured by hot pressing revealing interesting mechanical properties: a tensile modulus of 30 GPa and a damping coefficient, tan δ, of 0.03. POLYM. ENG. SCI., 59:2443–2448, 2019. © 2019 Society of Plastics Engineers