Bulk ultrafine grained metal matrix composites (MMC) have attracted much attention of many researchers due to their potential in terms of excellent mechanical properties for engineering applications, such as high strength, which can be two or more times of that of their coarse grained counterpart. Bulk ultrafine grained Cu-3wt.%C MMC samples were produced by Ball-Milling (BM) followed by Spark Plasma Sintering (SPS), at a temperature of 900 degrees C. The Cu-C MMC was compacted progressively by repeating the BM + SPS procedure without changing the weight ratio between Cu and graphite. The room temperature creep behavior, and the strain rate sensitivity (SRS) were inspected by using nanoindentation measurements. Strain rate ranged 0.0025-to-0.5 s(-1), and the contact dwelling times ranged 5-to-300 s. A secondary steady-state regime was reached starting from a dwelling time of 120 s irrespective of the strain rate and Cu-C compaction level. A negative trend of the SRS exponent with Cu-C compaction was obtained, with creep stress exponent as high as 28. These results were discussed according to the microstructure features that differentiated the Cu-3wt.% C MMC obtained by the progressive BM thorn SPS compaction levels. (C) 2018 Elsevier B.V. All rights reserved.

This work reports on the use of graphite as dispersoid to strengthen Cu. Material processing involved two-stage cycles of ball milling and spark plasma sintering, respectively for the dispersion of graphite nanoparticles into nanostructured Cu and the formation of dense compacts with relatively large Cu grains. The 3 wt% of graphite allows progressive hardening and stiffening of the Cu-graphite composite, showing the potential of graphite as effective dispersoid upon suitable processing. (C) 2018 Elsevier B.V. All rights reserved.

Ball milling (BM) a Cu nanopowder resulted in an increase of the average grain size from 8 to 52 nm, followed by a gradual decrease to 19 nm. In contrast, the grain size of coarse-grained Cu decreased monotonically from 290 nm to 19 nm. Fitting a model to the kinetic curves indicates that the two processes have similar activated volumes during collisions. It also reveals that particles over 100 nm are formed when nanoparticles are compressed during a collision for the first time. (C) 2017 Elsevier B. V. All rights reserved.

Porous clay ceramics represent an important class of construction materials. Their properties are strongly conditioned by microstructure features. In particular, a special attention has to be paid to porosity (pore fraction, pore shape, pore size, pore size distribution and topology distribution). In this work, thermal behaviour of porous ceramics has been studied comparing different modelling procedure. Fractal modelling, proposed in this paper, proves to be most reliable in predicting thermal behaviour of porous ceramics. For this reason, a design procedure for obtaining porous structures with specific thermal properties has been illustrated.

The controlled growth of Ag nanoparticles into graphene–TiO2 mesoporous films has been triggered by hard X-ray exposure provided by a synchrotron storage ring. The kinetic process has been studied by UV–visible spectroscopy as a function of the X-ray dose and compared to the nanoparticle growth induced in a bare mesoporous titania matrix. The graphene layers act as a preferential nucleation sites, allowing a faster nucleation of the nanoparticles. Moreover, the growth of larger nanoparticles is also promoted as a function of the exposure dose. The combined bottom-up and top-down approach to fabricate nanocomposites porous films embedding both graphene and plasmonic nanoparticles is expected to be a fundamental tool for the design of new analytical platforms based on the enhancement of the Raman signals.

Catalytic core–shell nanoparticles were obtained by coating an iron oxide core with a hybrid organic–inorganic silica shell using vinyl-triethoxy-silane and amino-propyl-triethoxy-silane. The amino group was further functionalised with arginine, used as catalytic moiety for the inactivation of organophosphate pesticides through hydrolysis. By exploiting the vinyl groups of the organosilica as anchorage, an additional outer layer made by molecularly imprinted organogel was built up through high-dilution radical polymerisation. The resulting organogel contains the imprinting complex, which derives from the guanidinium groups of the arginine and the organophosphate used as molecular template. The removal of the organophosphate from the imprinted cavities allowed obtaining core–shell magnetic nanoparticles with a molecularly imprinted acrylamide-based outer layer. These nanoparticles are capable of hydrolysing the commercial pesticide Paraoxon with a reaction rate 50 % faster than the corresponding background hydrolysis.

The Molt del Bare-1 site is located in south-central Pyrenees (Spain) and is dated to about 66.5 Ma (latest Cretaceous), just before the end Cretaceous mass extinction that wiped out most dinosaurs and many other groups of organisms. The site has yielded one of the richest fossil assemblages of the continental upper Maastrichtian from western Europe. A combined investigation by X-ray fluorescence (XRF), Fourier Transform Infrared spectroscopy attenuated total reflectance (FTIR-ATR) and powder X-ray diffraction (XRD), supplemented with the Rietveld analysis, was conducted on twenty-seven fossil bone samples from Molt del Barb-1 vertebrate-bearing fossil site to investigate taphonomy and diagenetic processes in terms of physico-chemical properties.The XRD analysis confirms the unusual presence of celestite and other rare sulphates in the bone structure. Previous explanations of the presence and sometimes abundance of celestite in the fossil bones from this site were based on the supposed total absence of marine water in the original depositionary environment. New geological information suggesting the possibility of marine influence allows formulating an alternative hypothesis focused on the peculiar environment of deposition of Mali del Bard-1 site. (C) 2016 Elsevier B.V. All rights reserved.

Graphene sheets increase the Raman signal through a chemical enhancement mechanism that gives rise to graphene-mediated enhanced Raman scattering (GERS). The low enhancement factor and the surface available for analysis are, however, a limitation on the application of GERS. We have, therefore, developed a new GERS platform, which is based on mesoporous ordered films made of titania anatase containing dispersed sheets of exfoliated graphene. The analytical enhancement factor has revealed that the combination of titania and graphene produces a significant increase in GERS response using Rhodamine 6G as molecular probe. This is a new effect, which we have defined as Ti-GERS (titania-induced graphene-mediated ERS), and is attributed to synergic interfacial interactions between graphene sheets and titania at the nanocrystal edges within the nanocomposite. In the future, the Ti-GERS effect is expected to foster a development of better performing Raman-based analytical devices avoiding the use of expensive noble metals.

We have addressed an X-ray fluorescence (XRF) and X-ray diffraction (XRD) on a collection of thirteen fossil bone belonging to the Molí del Baró 1 paleontological site located near Sant Romà d'Abella (Isona i Conca Dellà Municipality, Lleida Province, Spain, dated to about 66.5 Ma, to investigate the fossilization occurred in this site in terms of physico-chemical properties. As a general behaviour, the XRD patterns showed the bioapatite mineral at a varying level of percentage, and accordingly, the correspondent XRF spectra turned out to be mainly dominated by the presence of Ca, obviously accompanied by phosphorus. Simultaneously, other elements such as Sr, Fe, Ba and Zn were found at non-negligible concentration levels and helped to assign the phase components in the XRD spectra. In three specimens, it was observed by XRD the rather unusual case where the original bioapatite bone mineral was completely substituted for by other mineralogical phases. In addition to this, celestite was also found as an important phase in ten specimens out of the thirteen examined. The occurrence of celestite in the bone structure appears a rather unusual observation within the literature of bones diagenesis. Its provenance is generally ascribed to marine vertebrate organisms, but the presence in the fossil bones of this site, where no evidence of marine environment exists, can be reconciled with occurrence of refluxing processes involving diagenetically altered fluids which were discharged into beds containing strontium sulphate-rich waters.

A new approach towards the design of smart nanotextiles with innovative properties is presented. Silica (SiO2), titania (TiO2), and silver (Ag) nanoparticles (NPs), were synthesized without the use of any toxic organic compound and then were used, alone and in combination, to functionalize wool fabrics. Electrostatic forces, influenced by a low pH of the solutions, allowed the interactions between wool fabrics and NPs, enabling a robust functionalization. This was verified by X-ray microfluorescence and visualized by scanning electron microscopy measurements. The antibacterial Ag NPs were embedded in a polymer, alginic acid, to reduce the possible side effect due to their direct contact with the skin. SiO2 NPs, instead, were used to change the hydrophilicity of wool while the functionalization with TiO2 NPs was chosen to provide self-cleaning properties. The antibacterial activity of the fabrics was studied against the bacteria Escherichia coli, while the hydrophilicity of wool was studied by contact angle measurements and the self-cleaning properties were tested by estimating the visible discoloring of a dye stain under sunlight irradiation. Interestingly the combination of three different types of NPs provided the best results. SiO2 and Ag made the wool superhydrophilic providing at the same time the best antibacterial properties, while fabrics with titania (alone or in combination) were hydrophobic and showed the best self-cleaning properties.

Silica mesoporous nanocomposite films containing graphene nanosheets and gold nanoparticles have been prepared via a one-pot synthesis using silicon tetrachloride, gold(III) chloride tetrahydrate, a 1-N-vinyl-2-pyrrolidone dispersion of exfoliated graphene and Pluronic F127 as a structuring agent. The composite films have shown graphene-mediated surface-enhanced Raman scattering (G-SERS). Graphene has been introduced as dispersed bilayer sheets while gold has been thermally reduced in situ to form nanoparticles of around 6 nm which preferentially nucleate on the surface of the graphene nanosheets. The presence of graphene and gold nanoparticles does not interfere with the self-assembly process and the formation of silica mesoporous films ordered as 2D hexagonal structures. The material has shown a remarkable analytical enhancement factor ranging from 80 up to 136 using rhodamine 6G as a Raman probe. The films have been characterised by grazing incidence X-ray diffraction, FTIR and UV-vis spectroscopy studies; transmission electron microscopy and spectroscopic ellipsometry have been used to study the morphology, thickness and porosities of the samples. Raman spectroscopy has been employed to characterise the graphene nanosheets embedded into the mesoporous films and the enhanced Raman scattering.

Superparamagnetic iron oxide nanoparticles of magnetite have been grafted on the surface of a hybrid organic–inorganic film prepared using an organically modified alkoxide, 3-glycidoxypropyltrimethoxysilane, as precursor. A solventless synthesis of the hybrid films at high pH has been employed and the surface chemistry of the deposited films has been processed by controlling the aging time of the sol. The films have been characterized by FTIR, Raman and UV spectroscopy and grazing incidence X-ray diffraction. Films prepared with fresh sols have shown a mixed presence of epoxides and hydroxyls on the surface, which enabled the successful grafting of the iron oxide nanoparticles. Films from aged sols, which contain only hydroxyls, have failed to bind the iron particles but have instead shown the capability of grafting ceria nanoparticles. This method has, therefore, allowed a direct grafting of nanoparticles on the hybrid surface without any post-synthetic functionalization step. Moreover, the phase transition induced in iron oxide nanoparticles by means of a laser beam has been exploited to pattern the film surface creating different domains of magnetite and hematite.

Among the myriad microfabrication approaches, Deep X-ray Lithography (DXRL) takes advantage of the high penetration depth of hard X-rays. For the first time, this feature has been exploited for the precise control of surface chemical functionalities on a thick porous ceramic material. As a proof of concept, porous alumina membranes with controlled thickness (50 mu m) have been chosen to test the potential of DXRL. The Al2O3 membranes were decorated with fluoro- and amino-silanes. These functionalized ceramic membranes were exposed to hard X-rays in a synchrotron facility, which allowed for the selective decomposition of the chemical functionalities in controlled areas. The water contact angle of hydrophobic-functionalized samples was measured to confirm the decomposition of the fluoro-silane in the exposed area, and water diffusion through the 200 nm pores of the alumina membranes was observed to occur only in the exposed area. The patterned amino-functionalized Al2O3 samples were tested with an alcoholic solution containing Au cations, where it was found that gold nanoparticles only formed in the unexposed areas, whereas the amino functionality survived the radiation damage induced by the X-rays.

Graphene–silica films with high optical transparency have been obtained by adding a dispersion of exfoliated graphene into a silica sol.

We conducted an X-Ray Fluorescence investigation on bone fragments belonging to King Peter III of Aragon and Queen Blanche of Anjou. The spectroscopic analysis was carried out in selected points of the bone fragments. Several transitional elements normally unexpected in the bone composition have been found at varying level of concentration. The presence of these elements was interpreted in relation to chemical treatments for mummification of bodies as well as to dietary habits, including tools used for cooking and for the consumption of food.

To fully exploit the potential of self-assembly in a single step, we have designed an integrated process to obtain mesoporous graphene nanocomposite films. The synthesis allows incorporating graphene sheets with a small number of defects into highly ordered and transparent mesoporous titania films. The careful design of the porous matrix at the mesoscale ensures the highest diffusivity in the films. These exhibit an enhanced photocatalytic efficiency, while the high order of the mesoporosity is not affected by the insertion of the graphene sheets and is well-preserved after a controlled thermal treatment. In addition, we have proven that the nanocomposite films can be easily processed by deep X-ray lithography to produce functional arrays.

The process of dimerization of rhodamine 6G at high concentrations in solution and when incorporated in a solid state matrix is well known but the dimer response to photodegration is still not well understood. Silica sol-gel films have been doped with rhodamine 6G with a concentration up to 10(-1) M to form large amounts of dimers within the matrix. Fluorescence and UV absorption spectra have shown that both not-fluorescent H-dimers and fluorescent J-dimers together with the monomer form of rhodamine 6G are present in the matrix. Upon exposure up to 11 h to UV light a selective photodegradation of the different species has been finally observed. Analysis of the absorption spectra has shown that the H-type dimers are more resistant to photodegradation with respect to the J-type dimers. (C) 2013 Elsevier B.V. All rights reserved.

Nanocomposite thin films formed by mesoporous titania layers loaded with ceria nanoparticles have been obtained by combining bottom-up self-assembly synthesis of a titania matrix with top-down hard X-ray lithography of nanocrystalline cerium oxide. At first the titania mesopores have been impregnated with the ceria precursor solution and then exposed to hard X-rays, which triggered the formation of crystalline cerium oxides within the pores inducing the in situ growth of nanoparticles with average size of 4 nm. It has been observed that the type of coordinating agent in the solution plays a primary role in the formation of nanoparticles. Different patterns have been also produced through deep X-ray lithography by spatially controlling the nanoparticle growth on the micrometer scale. The radical scavenging role of the nanocomposite films has been tested using as a benchmark the UV photodegradation of rhodamine 6G. After impregnation with a rhodamine 6G solution, samples with and without ceria have shown a remarkably different response upon exposure to UV light. The dye photodegradation on the surface of nanocomposite films appears strongly slowed down because of the antioxidation effect of ceria nanoparticles.

The present work is aimed at developing a titania-based mesoporous film with catalytic properties toward organophosphate pesticides by combining two different approaches: the molecular imprinting and the self-assembly with a supramolecular template. The mesoporosity of the material has been obtained by using a tri-block copolymer (Pluronic F127) as a micellar template while the molecular imprinted cavities have been templated by a complex between La3+ and bis-4-nitro-phenyl-phosphate. The template removal allowed opening, in one step, both the mesopores and the imprinted cavities with a simultaneous estimation of the active sites. The catalytic activity of the molecularly imprinted and not imprinted films toward the pesticide Paraoxon® has been evaluated by means of UV-Vis spectroscopy titration of the 4-nitro-phenolate released by the Paraoxon® hydrolysis. The analysis of the initial rates of molecularly imprinted and not imprinted films has shown that the presence of a very low number of molecular cavities improves the catalytic properties of the imprinted film when compared to the not imprinted films and the background hydrolysis.