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Chiroptical activity in luminescent all-inorganic cesium copper bromide produced via a ligand-assisted reprecipitation method in the presence of arginine.

Chiral semiconductor quantum dots have recently received broad attention due to their promising application in several fields such as sensing and photonics. The extensive work in the last few years was focused on the observation of the chiroptical properties in binary Cd based systems. Herein, we report on the first evidence of ligand-induced chirality in silver indium sulfide semiconductor quantum dots. Ternary disulfide quantum dots are of great interest due to their remarkable optical properties and low toxicity. Non-stoichiometric silver indium sulfide quantum dots were produced

The use of readily prepared bisphosphonic acids obtained in few steps through a thio-Michael addition of commercially available thiols on tetraethyl vinylidenebisphosphonate enables the straightforward surface modification of amorphous mesoporous zirconia nanoparticles. Simple stirring of the zirconia nanoparticles in a buffered aqueous solution of the proper bisphosphonic acid leads to the surface functionalization of the nanoparticles with different kinds of functional groups, charge and hydrophobic properties. Formation of both chemisorbed and physisorbed layers of the bisphosphonic acid take place, observing after extensive washing a grafting density of 1.1 molecules/nm2 with negligible release in neutral or acidic pH conditions, demonstrating stronger loading compared to monophosphonate derivatives. The modified nanoparticles were characterized by IR, XPS, ζ-potential analysis to investigate the loading of the bisphosphonic acid, FE-SEM to investigate the size and morphologies of the nanoparticles and 31 P and 1 H MAS NMR to investigate the coordination motif of the phosphonate units on the surface. All these analytical techniques demonstrated the strong affinity of the bisphosphonic moiety for the Zr(IV) metal centers. The functionalization with bisphosphonic acids represents a straightforward covalent approach for tailoring the superficial properties of zirconia nanoparticles, much straightforward compared the classic use of trisalkoxysilane or trichlorosilane reagents typically employed for the functionalization of silica and metal oxide nanoparticles. Extension of the use of bisphosphonates to other metal oxide nanoparticles is advisable.

A new instrumental neutron activation analysis (INAA) for the simultaneous determination of titanium (TiO

We report on a Cu(ii) catalyzed process for the production of cysteine based chiral carbon dots; the process does not require any thermal treatment and the carbon dot formation is driven by the production of reactive radical species that are generated in the reaction media by the catalytic role played by the multivalent transition metal. The nanomaterial presents a well-defined chirality and the enantioselectivity of the synthesis is proved by the isolation of both the carbon dot enantiomers. We focused our attention on the processes that take place during the carbon dot formation and the relationship with the structure of the organic starting material. Thanks to the comparison of reactions conducted with different organic substrates whose thiyl radical chemistry is known, we recognized a non-trivial role of the radical hydrogen abstraction reactions in the carbon dot formation process. The reported process allows access to a large variety of analyses to monitor the reaction mixtures during the reaction course. Finally, we report a detailed analysis on the evolution of optical chirality during the synthesis and related this feature with the formation mechanism of the nanomaterial revealing significant evidence on the chirality origin and structure of chiral carbon dots.

We report on a Cu(II) catalyzed process for the production of cysteine based chiral carbon dots; the process does not require any thermal treatment and the carbon dot formation is driven by the production of reactive radical species that are generated in the reaction media by the catalytic role played by the multivalent transition metal. The nanomaterial presents a well-defined chirality and the enantioselectivity of the synthesis is proved by the isolation of both the carbon dot enantiomers. We focused our attention on the processes that take place during the carbon dot formation and the relationship with the structure of the organic starting material. Thanks to the comparison of reactions conducted with different organic substrates whose thiyl radical chemistry is known, we recognized a non-trivial role of the radical hydrogen abstraction reactions in the carbon dot formation process. The reported process allows access to a large variety of analyses to monitor the reaction mixtures during the reaction course. Finally, we report a detailed analysis on the evolution of optical chirality during the synthesis and related this feature with the formation mechanism of the nanomaterial revealing significant evidence on the chirality origin and structure of chiral carbon dots.

Background: TiO2 nanoparticles (TiO2 NPs) are the nanomaterial most produced as an ultraviolet (UV) filter. However, TiO2 is a semiconductor and, in nanoparticle size, is a strong photocatalyst, raising concerns about photomutagenesis. Mesoporous silica nanoparticles (MSN) were synthetized incorporating TiO2 NPs (TiO2@MSN) to develop a cosmetic UV filter. The aim of this study was to assess the toxicity of TiO2@MSN, compared with bare MSN and commercial TiO2 NPs, based on several biomarkers. Materials and Methods: Human peripheral blood mononuclear cells (PBMC) were exposed to TiO2@MSN, bare MSN (network) or commercial TiO2 NPs for comparison. Exposed PBMC were characterized for cell viability/apoptosis, reactive oxygen species (ROS), nuclear morphology, and cytokines secretion. Results: All the nanoparticles induced apoptosis, but only TiO2 NPs (alone or assembled into MSN) led to ROS and micronuclei. However, TiO2@MSN showed lower ROS and cytotoxicity with respect to the P25. Exposure to TiO2@MSN induced Th2-skewed and pro-fibrotic responses. Conclusions: Geno-cytotoxicity data indicate that TiO2@MSN are safer than P25 and MSN. Cytokine responses induced by TiO2@MSN are imputable to both the TiO2 NPs and MSN, and, therefore, considered of low immunotoxicological relevance. This analytical assessment might provide hints for NPs modification and deep purification to reduce the risk of health effects in the settings of their large-scale manufacturing and everyday usage by consumers.

We report a microwave assisted synthesis of NaNbO3 perovskite mesocrystals with a hierarchical morphology formed by the self-assembly of nanoparticles in particle clusters. The synthesis method combines non-aqueous sol–gel synthesis and microwave heating in a single step process that allows us to isolate crystalline single phase NaNbO3 in few minutes. A detailed investigation of the effect of the reaction temperature on the crystallinity and morphology of the product was conducted. The synthesis stabilizes the unusual orthorhombic phase Pmma, a property that can be ascribed to the crystal size (24 nm). TEM and SAED analyses show that the hierarchical polycrystalline particles behave as single crystals, a feature related to a non-classical crystallization mechanism. Moreover, the optical bandgap of this NaNbO3 phase was estimated for the first time. The results suggest the potential of this synthetic procedure for the fast production of high quality tertiary oxide nanocrystals.

Bismuth-based (nano)materials have been attracting increasing interest due to appealing properties such as high refractive indexes, intrinsic opacity, and structural distortions due to the stereochemistry of 6s

This work systematically compares both structural features and photocatalytic performance of a series of graphitic and amorphous carbon dots (CDs) prepared in a bottom-up manner from fructose, glucose, and citric acid. We demonstrate that the carbon source and synthetic procedures diversely affect the structural and optical properties of the CDs, which in turn unpredictably influence their photo electron transfer ability. The latter was evaluated by studying the photo-reduction of methyl viologen. Overall, citric acid-CDs were found to provide the best photocatalytic performance followed by fructose- and glucose-CDs. However, while the graphitization of glucose- and citric acid-CDs favored the photo-reaction, a reverse structure–activity dependence was observed for fructose-CDs due to the formation of a large graphitic-like supramolecular assembly. This study highlights the complexity to design in advance photo-active bio-based carbon nanomaterials.

In the field of nanomaterials, multifunctional nanosystems play a prominent role in many applications as new magnetically recoverable catalysts, information processing, fuel cells, efficient bio/na...

[Image: see text] There is the need for reproducible, simple, high-yielding synthetic protocols aimed at obtaining carbon dots (CDs) with controlled fluorescence, photothermal and photochemical behavior, surface properties, biocompatibility, tumor targeting ability, drug absorption biodistribution, and tumor uptake. This Letter describes a systematic study on the effect of glucose, fructose, and ascorbic acid as starting materials for the preparation of highly luminescent CDs, characterized by a blue emission. Their composition and morphology are investigated by titration of OH surface groups, spectroscopic techniques, and high-resolution transmission electron microscopy (HR-TEM), and their toxicity was tested toward HeLa cells. CDs made using fructose were toxic, while those made from glucose and ascorbic acid showed good biocompatibility. The reproducible and simple synthetic procedure yields luminescent biomass-derived CDs for combined cancer therapy and diagnostics. Their doxorubicin (DOX) drug uptake was measured by spectrofluorimetry, indicating a crucial role of the morphologies of the CDs in controlling DOX loading. The glucose derived CDs showed up to 28% w/w of DOX loading.

Some crystallographic considerations on the novel orthorhombic ZrO2 (o-ZrO2) stabilized at ambient conditions by Ta substitutional doping are presented. Specifically, how the Ta-doped o-ZrO2 was observed for the first time by conventional X-ray diffractometry (XRD) is reported, after which the ab initio and non-ab initio procedures used to resolve its crystal structure are detailed. The crystal structure is then explicitly reported (i.e., space group and cell parameters, as well as atomic positions of the asymmetric unit). It is also shown that this novel Ta-doped o-ZrO2 has a crystal structure similar, but not identical, to the high-pressure o-ZrO2. Additionally, given that the crystal structure of the Ta-doped o-ZrO2 is identified as being a symmetry-breaking distortion of the typical tetragonal ZrO2 (t-ZrO2) stabilized with the commonest dopants, a complete analysis is also made of the structural distortions relating both the Ta-doped o-ZrO2 and the high-pressure o-ZrO2 to the t-ZrO2. Finally, a justification for the apparent greater immunity of the Ta-doped o-ZrO2 to aging is provided.

A novel fine-grained orthorhombic ZrO2 ceramic stabilized with 12 mol% Ta doping was fabricated by spark-plasma sintering from home-made powders, and its high-temperature mechanical properties evaluated for the first time by compressive creep tests in both Ar and air. It was found that the high-temperature plasticity of the ceramic deformed in Ar, under which the Ta-doped orthorhombic ZrO2 is a black suboxide with abundant oxygen vacancies in its crystal structure, is controlled by grain boundary sliding (stress exponent ∼2, and activation energy ∼780–800 kJ/mol). However, the high-temperature plasticity of the ceramic deformed in air, under which the Ta-doped orthorhombic ZrO2 is a white oxide due to the elimination in situ of oxygen vacancies, is controlled by recovery creep (stress exponent ∼3, and activation energy ∼750 kJ/mol). It was also observed that black Ta-doped orthorhombic ZrO2 is more creep resistant than its white counterpart with the same grain size, and that the former deforms as the more conventional Y2O3-stabilized ZrO2 does., This work was supported by the Junta de Andalucía under Grant nº P12-FQM-1079 and by the Junta de Extremadura under Grant nº GR15078, co-financed with FEDER Funds. Financial support from the Ministerio de Economía y Competitividad (Government of Spain) and FEDER Funds under Grants nº MAT2015-71411-R and MAT2016-76638-R is gratefully acknowledged as well.

The development of new safe inorganic UV filters to effectively protect the skin from ultraviolet (UV) radiation effects is an emerging issue. Bismuth titanate-based UV filters embedded into mesoporous silica nanoparticles (MSN) represent a new class of inorganic sunscreens, with excellent UVA and UVB shielding properties. In addition, the presence of bismuth ions promotes a self-sealing process, allowing (i) the entrapment of the active phases in the deepest core of the system and (ii) the formation of an external glassy silica layer with a consequent suppression of the photocatalytic activity. In this work, aimed at studying in detail the self-sealing mechanism and accessing the role of bismuth ions in the formation of the system, a series of samples impregnated with a different amount of bismuth were investigated. The self-sealing process already occurs at the lowest content of bismuth and the mechanism is demonstrated to be triggered by the ability of Bi to work as a low-melting point agent for silica. Finally, a sunscreen formulation containing the new UV filter was prepared and the Sun Protection Factor (SPF), the pH and the viscosity were measured, demonstrating the potential of the proposed material for large-scale applications.

The present study reports the results of a combined approach in investigating the alteration phenomena on a contemporary artwork, Senza Titolo, by Nunzio di Stefano. The oeuvre, created in 2001, is composed by seven lead carved panels coated with Paraloid B72. After having being stored for several years in wood boxes, it was acquired in 2015 and, only at that time, the surface showed an evident deterioration In situ analyses, by means of contactless external reflection infrared spectroscopy (ERFTIR), have shown that the alterations products are in the form of basic lead carbonate and, surprisingly, of lead carboxylate. The presence of these products were supposedly due to VOCs attack during the storage in wood boxes. The formation of lead carboxylate, due to the interaction among lead substrate and acetic and formic acids (the major components of the VOCs mixture), was investigated through a laboratory accelerated ageing. The effect of VOCs was studied on the lead substrate, on the acryl coating and on a series of mockups simulating Senza Titolo. The combination of surface and punctual analyses, by means of ERFIR and mu-FTIR, showed that the formation of alteration products is a relatively fast process. The alteration path involves firstly the absorption of VOCs moisture on the Paraloid B72 surface, immediately followed by corrosion processes, leading to hydrocerussite, lead acetate and formate. The presence of the polymeric coating controls the transformation of lead carboxylates to basic lead carbonate. Laboratory results have consolidated those obtained by in situ contactless investigations, confirming ERFTIR as powerful tool in assessing the state of conservation of Cultural Heritage materials. (C) 2018 Elsevier Masson SAS. All rights reserved.

Background: TiO2 nanoparticles (TiO2 NPs) are the nanomaterial most produced as an ultraviolet (UV) filter. However, TiO2 is a semiconductor and, in nanoparticle size, is a strong photocatalyst, raising concerns about photomutagenesis. Mesoporous silica nanoparticles (MSN) were synthetized incorporating TiO2 NPs (TiO2@MSN) to develop a cosmetic UV filter. The aim of this study was to assess the toxicity of TiO2@MSN, compared with bare MSN and commercial TiO2 NPs, based on several biomarkers. Materials and Methods: Human peripheral blood mononuclear cells (PBMC) were exposed to TiO2@MSN, bare MSN (network) or commercial TiO2 NPs for comparison. Exposed PBMC were characterized for cell viability/apoptosis, reactive oxygen species (ROS), nuclear morphology, and cytokines secretion. Results: All the nanoparticles induced apoptosis, but only TiO2 NPs (alone or assembled into MSN) led to ROS and micronuclei. However, TiO2@MSN showed lower ROS and cytotoxicity with respect to the P25. Exposure to TiO2@MSN induced Th2-skewed and pro-fibrotic responses. Conclusions: Geno-cytotoxicity data indicate that TiO2@MSN are safer than P25 and MSN. Cytokine responses induced by TiO2@MSN are imputable to both the TiO2 NPs and MSN, and, therefore, considered of low immunotoxicological relevance. This analytical assessment might provide hints for NPs modification and deep purification to reduce the risk of health effects in the settings of their large-scale manufacturing and everyday usage by consumers.

In this study, an aqueous sol–gel chemistry route based on phosphoric acid as the phosphorus precursor, calcium acetate monohydrate and lanthanide (III) oxides as source of calcium and lanthanide ions, respectively, have been used to prepare europium- and thulium-substituted calcium hydroxyapatite (CHAp:Ln3+) powders. The ethylenediaminetetraacetic acid was used as complexing agent in the sol–gel processing. The final products were obtained by calcination of the dry precursor gels for 5 h at 1000 °C. The phase transformations, composition, and structural changes in the polycrystalline samples were studied by infrared spectroscopy, X-ray powder diffraction analysis, scanning electron microscopy and photoluminescence measurements. It was demonstrated, however, that the substitution of calcium by Eu or Tm proceeds in the CHAp at low concentration of lanthanide ion. Excitation and emission of Tm3+ in CHAp:Tm3+ spectra.

Core-shell systems have attracted increasing interest among the research community in recent years due to their unique properties and structural features, and the development of new synthetic strategies is still a challenge. In this work, we have investigated lanthanide-doped Bi2SiO5 nanocrystal formation inside mesoporous silica nanoparticles (MSNs). The role of both synthesis temperature and concentration of the bismuth precursor impregnated into the MSNs is discussed, showing an unprecedented strategy for the simultaneous stabilization of a crystalline core and a glassy shell. Temperature dependent synchrotron radiation X-ray powder diffraction (SR-XRPD) and high resolution transmission electron microscopy (HR-TEM) analyses allow one to follow the crystalline core growth. A mechanism for the formation of a Bi2SiO5@g-SiO2 core-shell nanosystem is proposed. In addition, the easy tunability of the color output of the upconverting system is demonstrated by means of suitable doping lanthanide ions with potential applications in several fields.

In this paper we report the study of down-shifting silica-zirconia glass and glass-ceramic films doped by Tb3+ions and Ag nanoaggregates, which combine the typical spectral properties of the rare-earth-ions with the broadband sensitizing effect of the metal nanostructures. Na-Tb co-doped silica-zirconia samples were obtained by a modified sol-gel route. Dip-coating deposition followed by annealing for solvent evaporation and matrix densification were repeated several times, obtaining a homogeneous crack-free film. A final treatment at 700 °C or 1000 °C was performed to control the nanoscale structural properties of the samples, resulting respectively in a glass (G) or a glass-ceramic (GC), where tetragonal zirconia nanocrystals are surrounded by an amorphous silica matrix. Ag introduction was then achieved by ion-exchange in a molten salt bath, followed by annealing in air to control the migration and aggregation of the metal ions. The comparison of the structural, compositional and optical properties are presented for G and GC samples, providing evidence of highly efficient photoluminescence enhancement in both systems, slightly better in G than in GC samples, with a remarkable increase of the green Tb3+PL emission at 330 nm excitation: 12 times for G and 8 times for GC samples. Furthermore, after Ag-exchange, the shape of Tb3+excitation resembles the one of Ag ions/nanoaggregates, with a broad significant absorption in the whole UV-blue spectral region. This broadband enhanced downshifting could find potential applications in lighting devices and in PV solar cells.

Five new luminescent ionic liquids (LILs) derived from tryptophan (Trp), phenylalanine (Phe) and the dipeptide Gly-Gly functionalized with a dansyl chromophore moiety, were synthesized by an original protocol involving both green reagents/solvents such as non-toxic dimethyl carbonate (DMC: MeOCO2Me) and 2-propanol, and reaction conditions. In particular, DMC was used for: (i) the synthesis of methyltrioctyl methylcarbonate onium salts [Q1mmn][MeOCO2] (Q = N, m = 1, n = 8; Q = P, n = m = 4, 8) by P- and N-methylation of trioctylphosphine and trioctylamine, respectively, and (ii) acid-catalyzed esterifications of Trp and Phe to produce the corresponding methyl esters (Trp-OMe and Phe-OMe). Both reactions proceeded with >90% isolated yields and a mass index (esterifications) as low as 4.5. 2-propanol was used as the solvent for N-dansylation reactions where Trp-OMe and Gly-Glyethyl ester hydrochloride (Gly-Gly-OEt) were coupled to dansyl chloride (DNS-Cl) as a luminescent precursor. A final anion metathesis step between methylcarbonate onium salts and N-dansyl amino acid derivatives gave desired LILs of general formula [Q1mmn][DNS-X] (X = Trp, Phe, and Gly-Gly) in quantitative yields and with by-products minimization. Upon excitation (λex = 340 nm) in MeCN, all LILs exhibited green luminescence with emission quantum yields in the range of 33–41% and monoexponential emission lifetimes of 12.6 ± 0.5 ns. Moreover, each compound showed a remarkable hypsochromic shift in the peak emission wavelength when dissolved in solvents of decreasing polarity (from water to MeCN, toluene and CH2Cl2, respectively). A photostability test by a 350 nm continuous excitation on thin films of LILs proved that, after 10 min, the GlyGly derivative fully retained its PL intensity, while this (intensity) decreased from 10 to 25% for other LILs.

Natural hydraulic lime-based mortars are recommended for retrofitting operations in historical buildings, primarily because of their high chemical, physical and mechanical compatibility with the existing ones; moreover, their autogenous and engineering self-healing capacities make them a more suitable material for the aforementioned interventions. This work proposes a methodology to quantify the autogenous self-healing in terms of recovery of the compression strength and ultrasonic pulse velocity in samples made of natural hydraulic lime mortars; specimens were pre-cracked at different ages (14–84 days) and levels of damage (70% of the compression strength in pre-peak regime; 90% of the compression strength in post-peak regime), and then cured under water up to 28 days. The capacity of healing after two loading/healing cycles has been also investigated. An interdisciplinary approach has been pursued characterising the mechanical aspects of the healing and the chemical nature of the products via SEM/EDS analyses. The results provide useful indication about the dependence of the self-healing capacity on the aforementioned variables.

In the field of novel applications involving upconverting processes, the determination of new strategies for realizing emission-tunable nanomaterials is a challenge. In this work the design of Y3+ and Er3+ codoped bismuth oxide-based upconverting nanoparticles is presented, evidencing that the active role of the matrix allows for the emission selectivity with chromaticity control. The bandgap of the bismuth oxide-based host can be manipulated in the range of 0.65 eV, consequently leading to upconversion emission color tunability from red to yellow-greenish. The resulting fine control of the nanoparticle chromaticity through accurate host bandgap engineering reveals a novel concept for the development of a new generation of upconverting nanophosphors.

The functionalization of mesoporous silica nanoparticles (MSNs) is a very important step in the preparation of these systems for a variety of applications. The surface of MSNs can be widely functionalized with different organic groups. There are essentially two ways to covalently modify the surface of nanoparticles: cocondensation and post-grafting. Generally, for both of these methods, the precursors are: [(R'O)3SiR] and [Cl3SiR]. The paper summarizes the main experimental contributions and the recent advances in the study of interactions among organosilanes and the MSNs surface. In particular, it provides relevant and innovative examples of Solid State and Solution NMR (SSNMR and SolNMR) and Fourier Transform InfraRed (FTIR) spectroscopy that highlight different possible approaches to understand the MSNs?pendants interaction.

Nanomedicine requires intelligent and non-toxic nanomaterials for real clinical applications. Carbon materials possess interesting properties but with some limitations due to toxic effects. Interest in carbon nanoparticles (CNPs) is increasing because they are considered green materials with tunable optical properties, overcoming the problem of toxicity associated with quantum dots or nanocrystals, and can be utilized as smart drug delivery systems. Using black tea as a raw material, we synthesized CNPs with a narrow size distribution, tunable optical properties covering visible to deep red absorption, non-toxicity and easy synthesis for large-scale production. We utilized these CNPs to label subcellular structures such as exosomes. More importantly, these new CNPs can escape lysosomal sequestration and rapidly distribute themselves in the cytoplasm to release doxorubicin (doxo) with better efficacy than the free drug. The release of doxo from CNPs was optimal at low pH, similar to the tumour microenvironment. These CNPs were non-toxic in mice and reduced the tumour burden when loaded with doxo due to an improved pharmacokinetics profile. In summary, we created a new delivery system that is potentially useful for improving cancer treatments and opening a new window for tagging microvesicles utilized in liquid biopsies.

A route for europium (III) tris-pyrazolyl borate complex [Eu(Tp)3] formation inside the pores of mesoporous silica nanoparticles (MSNs) has been established to yield a highly luminescent nanostructured hybrid. Two different in situ chemical precipitation techniques have been explored for the nanoencapsulation of the Eu3+ complex [Eu(Tp)3] inside the pore channels of mesoporous silica nanoparticles, by varying the sequence order of precursor impregnation. In the first method, the Eu salt is introduced into the pores by wet impregnation and removal of the solvent, followed by wet impregnation of the ligand. In the second approach, the addition sequence is reversed. The importance of the addition sequence was demonstrated by the successful formation of the europium (III) tris-pyrazolyl borate complex in the pore network by following the first approach. The observed pyrazol-1-yl borate (Tp) to Eu3+ intramolecular energy transfer, i.e., the antenna effect, verified the formation of the complex. Photoluminescence spectroscopy, X-ray diffraction, N2 adsorption, FTIR spectroscopy, and TEM were used to characterize the material.

In this work, we demonstrate that the martensitic t -> m phase transformation of ZrO2 powder stabilized with Eu3+ and Eu3+/Y3+ ions, can be effectively monitored by photoluminescence (PL) spectroscopy. As the luminescent properties of Eu3+ from within a host lattice are strongly influenced by the coordination geometry of the ion, we used the emission spectrum to monitor structural changes of ZrO2. We synthesized Eu3+-doped and Eu3+/Y3+-codoped samples via the coprecipitation method, followed by calcination. We promoted the martensitic transformation by applying mechanical compression cycles with an increasing pressure, and deduced the consequential structural changes from the relative intensities of the 5D0 -> 7F2 hypersensitive transitions, centered, respectively, at 606 and 613 nm whether the Eu3+ is in the eightfold coordinated site of the tetragonal phase or in the sevenfold coordinated site of the monoclinic phase. We suggest that the unique emission profile for Eu3+ ions in different symmetry sites can be exploited as a simple analytical tool for remote testing of mechanical components that are already mounted and in use. The structural changes observed by PL spectroscopy were corroborated by Xray powder diffraction (XRPD), with the phase compositions and volume fractions being determined by Rietveld analysis.

In this work we synthesized rare earth-doped yttria nanocrystals via the Pechini method. We used Ce(3+), Yb(3+) and Er(3+) as dopant ions and studied their behavior when they are simultaneously embedded in the yttrium oxide lattice. The tri-doped system exhibits both downshifting and up-converting properties, due to the presence of, respectively, cerium-erbium and ytterbium-erbium couples. Efforts were put into determination of the effects of the presence of increasing content of cerium. We synthesized a series of samples having the general formula (Y0.88-xCexYb0.1Er0.02)2O3, where x = 0.01, 0.02, 0.10, 0.20, and 0.40. The structural properties of the samples were analyzed by the X-ray powder diffraction (XRPD) technique and the morphological features were disclosed using transmission electron microscope (TEM) observations. Photoluminescence properties were tested by carrying out photoluminescence (PL) emission, photoluminescence excitation (PLE) and lifetime (LT) measurements.

The application of nanosized inorganic UV filters in cosmetic field is limited by their high photocatalytic properties that could induce the degradation or dangerous transformation of the organic molecules in sunscreen formulations. To overcome this problem and simultaneously enlarge the window of filter’s absorption, we propose the growth of bismuth titanates BixTiyOz into mesoporous silica nanoparticles (MSN). We investigated the chemical-physical properties by means of XRPD, TEM, UV–vis spectroscopy, N2 physisorption, XPS, and SF-ICP-MS analysis, while the influence on the environment was evaluated through photocatalytic tests. The growing process of this new nanosystem is discussed underlining the key role of the Bi3+ ion that, acting as a low-melting point agent for the silica framework, led to a self-sealing mechanism. The excellent UV shielding properties combined with a radical suppression of the photocatalytic activity make the proposed nanosystem a perfect candidate for the development of the ne...

A film-like or a thread-like system is a system such that one of its constituting homogeneous phases has a constant thickness $\delta$ or a constant normal section of largest diameter $\delta$. The stick probability function of this phase, in the limit $\delta \to 0$, naturally leads to the definition of the correlation function (CF) of a surface or a curve. This CF fairly approximates the generating stick probability function in the range of distances larger than $\delta$. The surface and the curve CFs respectively behave as $1/r$ and $1/r^2$ as $r \to 0$. In the two cases, this result implies that small-angle scattering intensities of the relevant samples respectively behave as $1/q^2$ and $1/q$ in an intermediate range of the scattering vector $q$ and as $1/q^4$ in the outermost one. One reports the analytic expressions of the pre-factors of these behaviors. It may happen that a sample looks thread-like at large scale resolution and film-like at smaller one. The surface and the curve CFs have explicitly been evaluated for some simple geometrical shapes. Besides, it is also reported the algebraic expression of the circular cylinder CF in terms of two elliptic integral functions, and it is shown that the limits of this CF, as the height or the radius of the cylinder approaches to zero, coincide with the CF of a disk or a linear segment, respectively., Comment: 37 pages, 18 figures

Eu:GdVO nanophosphorswith an average size of 60 nm, synthesized by a facile solvothermalmethod, were deposited on monocrystalline silicon wafers by a spray-coating technique with artworks anti-counterfeiting applications in mind. Atmospheric pressure plasma jet (APPJ) was used to deposit a silica-based layer on top of the nanometric luminescent layer, in order to improve its adhesion to the substrate and to protect it from the environment. The nanophosphors were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Coating composition was investigated by Fourier transform infrared spectroscopy (FT-IR) and its morphology was characterized by scanning electron microscopy (FEG-SEM). The film thickness was evaluated by means of ellipsometry and adhesionwas estimated by a peeling test. Luminescent properties of the nanophosphors deposited and fixed on silicon wafers were also measured. The whole layer resulted well-adhered to the silicon substrate, transparent and undetectable in the presence of visible light, but easily activated by UV light source., Università Ca' Foscari Venezia and Consortium INSTM are acknowledged for the financial support.

A synthesis of variably functionalized thiol-protected palladium nanoparticles (Pd-NPs) is presented. The nanoparticle syntheses are performed in acetone/water or tetrahydrofuranwater solutions, without making use of either phase-transfer agents or complex purification procedures of the as-synthesized nanoparticles. Small and mostly monodisperse thiol-protected Pd nanoparticles (Pd-NPs ~ 2 nm) have been prepared with 11-mercaptoundecanoic acid (MUA), 9-mercapto-1-nonanol (MN), 1-dodecanethiol (DT), or mixtures thereof, and a simple scale-up synthesis is also proposed. The role of PdII-thiolate species as metal precursors in the stage of nanoparticle synthesis and the influence of the reaction parameters on the final Pd-NPs size and size distribution are discussed. The formation of mixed-monolayer protected nanoparticles is achieved, with the final monolayer composition dictated by the thiols, initial molar ratio. Overall, the procedure presented here allows the preparation of functionalized nanoparticles with a high density of functional groups at the edge of the monolayer, with no need of place-exchange reactions. Specific postfunctionalization procedures conducted at the acid groups of the MUA-Pd monolayer are reported so as to widen the potential applicability of these amphiphilic nanoparticle precursors with respect to different applications in the field of material science. Finally, the successful use and the easy recycling/reuse of the Pd-NPs in a model Suzuki cross-coupling reaction are presented.

Manila clam Ruditapes philippinarum represents an important economic resource of Italian aquaculture. However, especially for Venice lagoon, health and environmental risks should be evaluated. A multidisciplinary approach was used. In particular, local production chain analysis and end-user requirements were investigated to assess manila clam safety and traceability in Northern Adriatic Sea. Moreover, the molecular and biochemical techniques demonstrated a good quality of the investigated farming sites, due to the absence of biotoxins. Molecular markers provided informations on the population genetics and specific genetic traits of Ruditapes philippinarum in Northern Adriatic Sea, which was investigated for the first time. The complexity of all these informations was simplified in a single useful tool: a database containing all the informations about the seafood product.

Polymer encapsulation of submicrometer-sized silica particles by synthesis of the polymer shell, poly(methyl methacrylate) under static conditions in a reaction medium free of surfactants and stabilizing agents is described. The Stöber method, a base-catalyzed hydrolysis and condensation of tetraethyl orthosilicate is used for the synthesis of the monodisperse colloidal dispersion of silica particles. The silica particles are subsequently modified in situ with the surface grafting of the silane coupling agent, 3-(trimethoxysilyl)propyl methacrylate. Encapsulation is achieved using tetraethyl orthosilicate as a reaction medium, in which a thermally initiated radical polymerization of methyl methacrylate is promoted in the presence of the modified particles by a seeding method which leads to a thin coating of poly(methyl methacrylate), and hence silica core-shell particles. The complete encapsulation of individual silica spheres by poly(methyl methacrylate) is visually evidenced by TEM microscopy which reveals the presence of a polymer shell coating up to 10 nm. Evidence for the presence of a poly(methyl methacrylate) shell is further corroborated by DSC/TGA, DRIFT-IR and NMR measurements.

The formation of silica particles by the ammonia-catalyzed hydrolysis of tetraethyl orthosilicate (TEOS) in the polyoxyethylene (5) nonylphenyl ether (NP-5)/cyclohexane/water microemulsion system was investigated by time-resolved small-angle X-ray scattering (SAXS). The SAXS data could be modeled as a combination of two species where one describes the silica-particle containing microemulsion droplets and the other the reverse droplets. The analysis allowed the determination of the evolution of the system of particles of silica and reverse droplets. A model of nucleation and growth of the silica particles is confirmed and the volume fraction versus time data for the silica particles is in agreement with first order kinetics with respect to TEOS concentration. Moreover to describe the long time evolution of the system, a correlation among the silica particles has been taken into account by introducing a structure factor with a local silica volume fraction eta = 0.1. This high local density is 2 orders of magnitude larger than the global silica fraction and can be explained in terms of depleting interaction.

Highly luminescent anionic Ln(III) ?-diketonate complexes of the formula [P8,8,8,1][Ln(dbm)4], with Ln = Eu3+ and Sm3+, [P8,8,8,1] = trioctylmethylphosphonium and dbm = 1,3-diphenylpropane-1,3-dione were synthesized. The single crystal X-ray structure of the samarium and europium complexes showed that the metal ion was surrounded by four ligands and that no water or solvent molecules were coordinated. The solid complexes showed good thermal stability up to 250 °C. The complexes easily dissolved in the ionic liquid trioctylmethylphosphonium bis(trifluoromethylsulfonyl)imide [P8,8,8,1][Tf2N], due to the presence of a common phosphonium countercation in the ionic liquid and in the Eu(III) and Sm(III) complexes. The photoluminescence of the complexes was studied in the solid state and in an ionic liquid as well as in acetonitrile (MeCN) as a solvent.

Different deposition methods of nanocomposite silica films with embedded Y2O3:Eu3 +, Tb3 + by atmospheric pressure plasma jet (APPJ) technology are presented. We found that a two-step strategy consisting in the APPJ deposition of a silica film on previously deposited nanophosphors is a very efficient method to obtain nanocomposite coatings with excellent adhesion to the substrate. Moreover the APPJ deposited silica film ensures protection of the luminescent nanoparticles and preserves the photoluminescence emission properties of the nanophosphors. Optically active coatings can be therefore deposited by using this technology.

Nanocarriers as theranostic agents are under the spotlight in modern nanomedicine, and mesoporous nanomaterials represent a class of devices of major interest. Zirconia is biocompatible, inert with good mechanical and thermal properties for in vivo biomedical applications. Although a few examples of zirconia nanoparticles have been described, a major limitation was the low surface area, which is fundamental for payload transport. Here, a simple and highly efficient method is described for the synthesis of spherical mesoporous zirconia nanoparticles (MZNs) with a high surface area through a neutral surfactant-assisted sol-gel method. The combination of alkali halides and vacuum extraction allowed stabilization of the shape and size of MZNs and to avoid porous network failure, respectively. In comparison to published synthesis procedures, a high surface area has been obtained. Biological experiments demonstrated that MZNs were biocompatible, cell permeable and degradable providing a proof of concept for theranostic applications. A comparison with the properties of mesoporous silica nanoparticles has also been performed.

In this paper, high concentration (up to 40% of rare earth with respect to the metal oxides) Eu 3+ -doped ZrO 2 , Y 2 O 3 and ZrO 2 –Y 2 O 3 systems were prepared both as bulk material and as nanoparticles embedded in SiO 2 . The latter nanocomposites were obtained as a result of a thermal treatment at 1000 °C of powder samples prepared by the sol–gel method. The combination of transmission electron microscopy (TEM), X-ray scattering (WAXS) and photoluminescence (PL) spectroscopy enabled us to obtain detailed information about morphology and composition of the rare earth-doped nanoparticles. In particular, for nanostructured samples, high luminescence has been observed in spite of a very high rare earth concentration in the active host.

Class I organic–inorganic hybrid materials consisting of zirconia and zirconia/silica matrices doped with europium(III)–1,10-phenanthroline complex were prepared by a catalyst-free sol–gel route. Two different experimental procedures were developed to incorporate the coordination compound into the matrix in order to study the possible influence of the preparation method on the optical properties of the rare earth ion. Besides, the effects of the annealing temperature and the composition of the matrix were investigated. Infrared spectra, Eu(III) luminescence lifetimes, relative emission intensities, excitation and emission spectra are reported. The products yielded under UV excitation strong red emission similar to the one of the neat coordination compound. The relative emission intensities and lifetimes show a maxima when determined as a function of annealing temperature, preparation procedure and matrix composition.

Ruthenium dioxide films were prepared by radio-frequency magnetron sputtering onto Si and Ti substrates. Films of different thicknesses (100-500 nm) were synthesized at substrate temperatures of 40, 350, and 450 °C. Their composition has been studied by Rutherford backscattering spectrometry, elastic recoil detection, and ion beam nuclear reaction analysis. Scanning electron microscopy and wide-angle X-ray scattering have been used for studying the surface texture of the samples and for their microstructural characterization, respectively. The electrochemical characterization by cyclic voltammetry has shown that, despite the high physical density of the films, compared with that obtained by the thermochemical methods, they exhibit large charge-storage capacities. For the materials synthesized at 350-450 °C, an explanation of these results has been sought in specific features of the RuO 2 rutile-type cell and columnar texture of the oxide film. The much higher capacity of the films synthesized at 40 °C would be rather due to a poor sintering of the oxide phase. Study of the chlorine evolution reaction in the samples prepared at 350 and 450 °C points to a Volmer-Tafel mechanism, with a chemical desorption rate-determining step, and significant radical intermediate coverage. Films deposited at 40 °C exhibited an unsatisfactory wear resistance under the anodic polarization required for the chlorine evolution reaction investigation.