Tubular-shaped stoichiometric chrysotile nanocrystals

Stoichiometric chrysotile tubular nanocrystals have been synthesized as possible starting materials for applications toward nanotechnology, and as a standard reference sample for the investigation of the molecular interactions between chrysotile, the most utilized asbestos, and biological systems. Chrysotile nanocrystals have been synthesized under controlled hydrothermal conditions, and have been characterized by chemical, morphological, structural, spectroscopic and microcalorimetric analyses. They show a constant cylinder-in-cylinder morphology constituted by two or three concentric subunits. Each single nanocrystal has a tubular shape of about 49 +/- 1 nm in outer maximum diameter, and a hollow core of about 7 +/- 1 nm. Structural investigation carried out on an Xray powder pattern allowed to improve the structural model proposed for chrysotile mineral samples. Synthetic chrysotile crystallizes in the monoclinic Cc space group with a= 0.5340(l) nm, b = 0.9241(l) nm, and c = 1.4689(2) nm, beta = 93.66(3)degrees

Cuttlefish bone scaffold for tissue engineering: a novel hydrothermal transformation, chemical-physical, and biological characterization

PURPOSE: Natural resources are receiving growing interest because of their possible conversion from a cheap and easily available material into a biomedical product. Cuttlefish bone from Sepia Officinalis was investigated in order to obtain an hydroxyapatite porous scaffold using hydrothermal transformation. METHODS: Complete conversion of the previous calcium carbonate (aragonite) phase into a calcium phosphate (hydroxyapatite) phase was performed with an hydrothermal transformation at 200 \ub0C (~ 15 atm), for four hours, with an aqueous solution of KH2PO4 in order to set the molar ratio Ca/P = 10/6 in a reactor (Parr 4382). The complete conversion was then analyzed by TGA, ATR-FTIR, x-ray diffraction, and SEM. Moreover, the material was biologically investigated with MC3T3-E1 in static cultures, using both osteogenic and maintenance media. The expression of osteogenic markers as ALP and osteocalcin and the cell proliferation were investigated. RESULTS: Cuttlefish bone has been successfully transformed from calcium carbonate into calcium phosphate. Biological characterization revealed that osteogenic markers are expressed using both osteogenic and maintenance conditions. Cell proliferation is influenced by the static culture condition used for this three-dimensional scaffold. CONCLUSIONS: The new scaffold composed by hydroxyapatite and derived for a natural source presents good biocompatibility and can be used for further investigations using dynamic cultures in order to improve cell proliferation and differentiation for bone tissue engineering

Determination of low levels of free fibres of chrysotile in contaminated soils by X-ray diffraction and FTIR spectroscopy

A new analytical method for the determination of low levels (0.01-1 wt%) of free fibres of chrysotile in contaminated clayey, sandy and sandy-organic soils is described. The detection limit of 0.01 wt% is reached with an enrichment of free fibres of chrysotile in the sample using a standard laboratory elutriator for sedimentation analysis. The chrysotile quantitative determination is performed both by X-ray powder diffraction, using the internal standard and reference intensity ratio methods, and by Fourier-transform infrared absorption spectroscopy. The procedure can be successfully applied to different soils after removal, by a thermal treatment, of the matrix components which can interfere. This straightforward method fulfils the request of public institutions and private companies for an appropriate quantitative determination of chrysotile-free fibres in contaminated soils

Synthesis of nanogranular Fe3O4/biomimetic hydroxyapatite for potential applications in nanomedicine: structural and magnetic characterization

We realized the synthesis of a novel nanogranular system consisting of magnetite nanoparticles embedded in biomimetic carbonate hydroxyapatite(HA), for prospective uses in bone tissue engineering. An original two-step method was implemented: in the first step, magnetite nanoparticles are prepared by refluxing an aqueous solution of Fe(SO4) and Fe2(SO4)3 in an excess of tetrabutilammonium hydroxide acting as surfactant; then,the magnetite nanoparticles are coated witha Ca(OH)2 layer,to induce the growth of HA directly on their surface, by reaction of Ca(OH)2 with HPO4 2−.Two nanogranular samples were collected with magnetite content∼0.8and∼4wt%. The magnetite nanoparticles and the composite material were investigated by x-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy.These analyses provided information on the structure of the nanoparticles(meansize∼6nm)and revealed the presence of surface hydroxylgroups, which promoted the subsequent growth of the HA phase, featuring a nanocrystalline lamellar structure.The magnetic study,by a superconducting quantum interference device magnetometer, has shown that both the as-prepared and the HA-coated magnetite nanoparticles are superparamagnetic at T=300K, but the magnetization relaxation process is dominated by dipolar magnetic interactions of comparable strength.In the three samples, a collective frozen magnetic regime is established belowT∼20K. These results indicate that the magnetite nanoparticles tend to form agglomerates in the as-prepared state,which are not substantially altered by the HA growth, coherently with the creation of electrostatic hydrogen bonds among the surface hydroxyl groups

The Influence of Uncertainty Contributions on Deep Learning Architectures in Vision-Based Evaluation Systems

Vision-based measurement (VBM) systems are powerful tool to extract quantitative information by acquiring video sequence or static images. When a VBM is applied to the evaluation of nominal properties, such as image characteristics, the term VBM is substituted with vision-based evaluation (VBE) by extending the framework of operation unit to a new concept of evaluation unit (EU) for the image analysis and machine learning phases. To this regard, deep learning (DL) approaches have gained an exponential interest in the research and industrial community, thanks to incredible flexibility toward visual words and the possibility to abandon subjective feature extraction procedures. From such an explosiveness of applications, it emerges the need to conduct studies on the capability of DL strategies to deal with uncertainty contributions, i.e., definitional uncertainty related to the measurand and reference uncertainty that may occur during the calibration process. In order to present a benchmark platform to analyze the effect of the major sources of uncertainties estimated, we use here an atomic force microscopy (AFM) imaging scenario for the evaluation of the effect of nanoparticles exposure on human cells in the laboratory. These studies are nowadays fundamental in toxicity analysis for monitoring the health conditions of workers and for protecting people from atherosclerosis disease. The performance of the proposed VBE-DL system to recognize cell alterations from the AFM images is related to three different sources of uncertainty and a critical analysis of the results achieved is provided