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The use of glassceramics in photocatalysis is an attractive option for the realization of smart optical fibers and self-cleaning windows. Here we present the photocatalytic activity of germanosilicate glasses embedding Ga2O3 nanocrystals prepared by batch melting and glass heat treatment. The powdered material is used for UV-assisted degradation of rhodamine in water. The kinetics show changes after repeated experiments. In the first cycle, the apparent rate is governed by a second-order reaction with a Gaussian-like shape, whereas the second cycle follows a first-order reaction. The modification appears to be correlated with perturbations in the defect population. Photoluminescence has been used to monitor the evolution of such defects. Kinetic data on photoreactions and defect formation have been modelled in a combined frame in which the defect concentration determines the photocatalytic activity. The results prove the photocatalytic ability of the studied glassceramics. Moreover, the general validity of the kinetic model can be of interest for other systems in which the photocatalytic response depends on photoreactive species concentration.

Water-in-salt solutions, i.e. solutions in which the amount of salt by volume or weight is larger than that of the solvent, are attracting increasing attention in electrochemistry due to their distinct features that often include decomposition potentials much higher than those of lower concentration solutions. Despite the high solubility of potassium acetate (KAC) in water at room temperature (up to 25 moles of salt per kg of solvent), the low cost, and the large availability, the use of highly concentrated KAC solutions is still limited to a few examples in energy storage applications and a systematic study of their physical-chemical properties is lacking. To fill this gap, we have investigated the thermal, rheological, electrical, electrochemical, and spectroscopic features of KAC/water solutions in the compositional range between 1 and 25 mol kg-1. We show the presence of a transition between the "salt-in-solvent" and "solvent-in-salt" regimes in the range of 10-15 mol kg-1. Among the explored compositions, the highest concentrations (20 and 25 mol kg-1) exhibit good room temperature conductivity values (55.6 and 31 mS cm-1, respectively) and a large electrochemical potential window (above 2.5 V).

Ilmenite, general formula FeTiO3, has been proposed as possible conversion anode material for lithium- and sodium-ion batteries, with theoretical capacity of 530 mAhg−1. Experimentally, the observed specific capacity for pristine ilmenite is far away from the theoretical value; for this reason, the control of morphology via alkaline hydrothermal treatment has been proposed as possible strategy to improve the electrochemical performance. At the same time FeTiO3 is prone to react with sodium and potassium hydroxide, as already demonstrated by studies on the degradation of ilmenite for the extraction of TiO2. In this paper we demonstrate that the alkaline treatment does not induce a morphological modification of the FeTiO3 powders but involved the degradation of the precursor material with the formation of different phases. A complete physicochemical and electrochemical characterization is performed with the aim of correlating structural and functional properties of the obtained products.

We report on design and fabrication of Ni 2+ -doped glass-ceramics from a low-alkali optical glass in Li 2 O-Na 2 O-Ga 2 O 3 -SiO 2 -GeO 2 system by melting technique and subsequent thermally controlled nano-crystallization. The analysis of differential scanning calorimetry, X-ray diffraction, transmission electron microscopy, absorption and fluorescence spectroscopy reveals, for the first time, the real possibility of optimizing the integrated intensity of Ni 2+ near-infrared emission through controlled pre-treatments at temperatures of nanophase nucleation, with the enhancement up to a factor of four with respect to gallium germanosilicate glass-ceramics obtained without pre-treatments. Importantly, the effects on the light emission are shown to be related to the influence of pre-treatment on size and size distribution of the gallium oxide nanocrystals which result from subsequent crystallization at higher temperature.

A multidisciplinary non-destructive study has been carried out on historical pipe organ fragments, trying to infer whether the spatial occurrence of different crystallographic phases (that is alpha-tin, beta-tin, cassiterite or romarchite) reflects the visible alterations patterns. We could indeed derive the presence of the beta-tin phase. Several tin oxide phases have been detected too, associated with the visible occurrence of “grey regions” and hole borders (mapped by Raman spectroscopy), and hydrate phases (mapped by neutron imaging). We aim to demonstrate that neutron and Raman techniques can give relevant indications in archaeometallurgy studies of cultural heritage artifacts, where only non-destructive experiments can be performed. The combination of the two probes could be considered a protocol to be applied in the characterization of tin based specimens.

The demand for new responsive materials is continuously growing in several areas as a result of approaching the physical limits of technologies, which now calls for a drastic change of strategy. Here, we report on memory responsive oxide-in-oxide nanostructured films obtained by radio-frequency sputtering of a 7.5Li2O–2.5Na2O–20Ga2O3–45GeO2–25SiO2 (mol%) glass target produced by melt quenching. Atomic force microscopy and scanning electron microscopy show that as-deposited oxide layers exhibit native nanophase separation, with the occurrence of Ga-rich oxide nanostructures – about 15 nm thick and 100 nm in diameter – incorporated in oxide layers about 70 nm thick. Interestingly, despite the wide band gap (above 4 eV), the nanostructured oxide films reveal the formation of unconventional electric field dependent charge transport paths across the material. The frequency and temperature dependence of electric conductivity and dielectric function highlights n-type conduction sustained by charge percolation through the oxide layer. Importantly, the results demonstrate the occurrence of conductivity changes by more than an order of magnitude in a few volts, and trapped charge values up to 1016 electrons per cm3.

Water in salt solutions are a new class of electrolytes developed with the aim of increasing the electrochemical stability of aqueous electrolytes without decreasing the transport properties. Among them, aqueous solutions of potassium acetate (CH3COOK, AcK) have received little attention, despite its large solubility in water at room temperature (25 mol kg−1) and the very low cost. With the idea of developing cost-effective and good performing Electrochemical Double Layer Capacitors (EDLCs), a symmetric device based on a low-cost coal derived carbon (F400) and highly concentrated AcK solutions as electrodes and electrolytes, respectively, was fabricated and optimized. The best results are obtained with the system F400/20 mol kg−1 AcK/F400 able to deliver a gravimetric energy density of 26 Wh kg−1 at an average power of 1.4 kW kg−1.

KLuS2 single crystal samples undoped and doped with a low (5 %) or high (38 %) concentration of trivalent thulium or ytterbium ions were synthesized in the form of thin hexagonal plates. The low phonon energy ( ∼ 220 cm−1) was confirmed using Raman spectroscopy. Samples were studied also by using optical absorption and emission as well as electron paramagnetic resonance spectroscopy and the observed spectral features are discussed. In particular, the 5 % Yb doped samples demonstrate homogeneous dopant distribution inside the material over the lutetium sites. No other signals either from potassium site or the exchange coupled ions were detected. For infrared transitions the luminescence kinetic was determined. Significantly broad infrared emission bands (at 1.4, 1.8 and 2.3 μm for Tm3+, 1 μm for Yb3+) and long decay times (e.g. 0.4 ms from 3H4 to 19 ms from 3F4 levels of Tm3+, 1.4 ms from 2F5/2 level of Yb3+) make those materials perspective for future laser development.

Gallium incorporation in silicate glasses gives rise to compounds in which the nucleation and growth of Ga-oxide nanostructures can be designer controlled so as to obtain a number of functional properties for photonic applications. However, despite planar geometry pertains to a large part of modern technology, no information is available yet on the scalability of Ga-oxide segregation mechanisms in oxide thin films. In fact, incorporated Ga-oxide nanostructures have only been obtained in bulk materials. Here we show that deposition of Ga-alkali-germanosilicate thin films by radiofrequency-plasma sputtering gives rise to Ga-oxide nanostructures incorporated in an amorphous matrix. X-ray diffraction, X-ray reflectivity, small-angle X-ray scattering, and atomic force microscopy data unveil the formation of lenticular nanoaggregates, only a few nm thick, even in as-deposited materials as a result of two-dimensional aggregation of spinel-like Ga2O3 nanoparticles. Importantly, the aggregate size distribution is controlled not only by the temperature but also by the film thickness when it is reduced from 102 nm to only a few nm. The results open the way to the design of oxide-in-oxide thin films with incorporated networks of nanostructures which can act as percolation paths for unconventional electric responses in neuromorphic functional systems.

Two bacterial strains, Achromobacter sp. (ACH01) and Sphingomonas sp. (SPH01), were isolated from a heavily polycyclic aromatic hydrocarbon (PAH)-contaminated soil (5431.3 ± 102.3 ppm) for their capacity to use a mixture of anthracene, pyrene, phenanthrene and fluorene as sole carbon sources for growth and for the capacity to produce biosurfactants. The two strains were exploited for bioaugmentation in a biopile pilot plant to increase the bioavailability and the degradation of the residual PAH contamination (99.5 ± 7.1 ppm) reached after 9 months of treatment. The denaturing gel gradient electrophoresis (DGGE) profile of the microbial ecology of the soil during the experimentation showed that the bioaugmentation approach was successful in terms of permanence of the two strains in the soil in treatment. The bioaugmentation of the two bacterial isolates positively correlated with the PAH depletion that reached 7.9 ± 2 ppm value in 2 months of treatment. The PAH depletion was assessed by the loss of the phyto-genotoxicity of soil elutriates on the model plant Vicia faba L., toxicological assessment adopted also to determine the minimum length of the decontamination process for obtaining both the depletion of the PAH contamination and the detoxification of the soil at the end of the process. The intermediate phases of the bioremediation process were the most significant in terms of toxicity, inducing genotoxic effects and selective DNA fragmentation in the stem cell niche of the root tip. The selective DNA fragmentation can be related to the selective induction of cell death of mutant stem cells that can compromise offsprings.

The knowledge advancement in the physics of silicon dioxide has promoted ground-breaking progress, from microelectronics to fibre optics. However, the SiO2 exciton decay mechanism is still mostly unrevealed. Here, we analyse the temperature dependence of interband-excited luminescence and the reflectivity by means of synchrotron radiation on a wide selection of SiO2 materials. This enables us to decouple the band-to-band recombination steps from non-radiative decay pathways that typically mask the relaxation mechanisms. We show that band-to-band excitations decay into two competitive correlated channels leading to green and red luminescence so far ascribed to independent transitions. Here we discuss the assignment to a dual relaxation route involving either ‘free’ or ‘interacting’ non-bridging-oxygen sites. Such an interpretation suggests an explanation for the elusive non-bridging-oxygen centres in quartz. The reflectivity spectra finally demonstrates a general relationship between exciton spectral position and bandwidth in SiO2 and clarifies the role of disorder in exciton localization. Silicon dioxide is a crucial material in the world of photonics but aspects of its optical decay mechanisms are still not fully understood. The authors use synchrotron radiation to analyse emission processes for different types of silica and quartz and deduce by what mechanisms they may occur.

Nanocrystals (NCs) surface characterization is a fundamental step for understanding the physical and chemical phenomena involved at the nanoscale. Surface energy and chemistry depend on particle size and composition, and, in turn, determine the interaction of NCs with the surrounding environment, their properties and stability, and the feasibility of nanocomposites. This work aims at extracting more information on the surface of different titanium dioxide polymorphs using1H-TD-NMR of water. Taking advantage of the interaction between water molecules and titanium dioxide NCs, it is possible to correlate the proton transverse relaxation times (T2) as the function of the concentration and the specific surface area (δp·Cm) and use it as an indicator of the crystal phase. Examples of three different crystals phase, rutile, anatase, and brookite, have been finely characterized and their behavior in water solution have been studied with TD-NMR. The results show a linear correlation between relaxivity (R2) and their concentration Cm. The resulting slopes, after normalization for the specific surface, represent the surface/water interaction and range from 1.28 g m-2s-1of 50 nm rutile nanocrystals to 0.52 for similar sized brookite. Even higher slopes (1.85) characterize smaller rutile NCs, in qualitative accordance with the trends of surface energy. Thanks to proton relaxation phenomena that occur at the NCs surface, it is possible to differentiate the crystal phase and the specific surface area of titanium dioxide polymorphs in water solution.

In this Letter, we present detailed absorption and emission data on nanostructured germanosilicate glasses and glass ceramics containing Ga2O3 nanophases and doped with Gd ions. The results show that these systems are suitable hosts for the enhancement of the excitation cross section of rare earth ions via energy transfer from the gallium oxide nanophase with a related quantum yield of 21%. The role of matrix composition and nanostructure morphology on the Gd emission is discussed.

Incorporation of doping ions in nanocrystals is a strategy for providing nanophases with functions directly related to ion features. At the nanoscale, however, doping can also activate more complex effects mediated by perturbation of the nanophase size and structure. Here, we report a paradigmatic case in which we modify grown-in-glass γ-Ga2 O3 nanophases by nickel or titanium doping of the starting glass, so as to control the concentration of oxygen and gallium vacancies responsible for the light emission. Optical absorption and luminescence show that Ni2+ and Ti4+ ions enter into the nanophase, but differential scanning calorimetry and X-ray diffraction indicate that Ni and Ti also work as modifiers of nanocrystal growth. As a result, doping influences nanocrystal size and concentration, which in turn dictate the number of donors and acceptors per nanocrystal. Finally, the chain of effects turns out to control both the intensity and spectral distribution of the light emission.

Long-life excimer-like structures Metal quantum clusters have ideal properties for medical applications such as imaging. The challenge is to prolong their transient properties for the fabrication of useful devices. Santiago-Gonzalez et al. arranged gold clusters in a supramolecular lattice held together by hydrogen bonding and showed that this material can be used for imaging of fibroblast cells. In the superstructure, the gold molecules can come together in the excited state as excimers and then dissociate to emit radiation. Because they are within a lattice, this behavior shows long-term stability. Furthermore, the lattice superstructure scavenges reactive oxygen species and reduces cell damage. Science , this issue p. 571

The design of a process to create yttrium aluminosilicate microspheres with a core–shell structure is of interest in the field of cancer brachytherapy. Glass microspheres with yttrium-depleted shell may indeed reduce the risk of 90 Y release into the organism. Here we show – by means of confocal micro-Raman scattering, microfluorescence, X-ray-fluorescence analysis, and IR spectroscopy – that yttrium depletion may be achieved by etching in HCl solution (pH 2) at a rate of 1 μm day −1 in bulk glass and 3 μm day −1 in glass microsphere (35 μm of diameter). Importantly, the spectroscopic results – collected in confocal configuration along the processed layer – indicate a high degree of structural reconstruction of the glass network, with the formation of an interconnected silicate-rich glass that surrounds a core of unmodified yttrium aluminosilicate. We also demonstrate that the process is driven by non-bridging oxygen sites, which regulate the hydroxylation and structural reconstruction of the glass within the Y-depleted layer. The analysis gives also some insight into open fundamental questions about the short-range structure and the chemical stability of this kind of glass, which is also important in photonics and nuclear waste disposal.

Fluorinated silica glasses with improved vacuum ultraviolet (VUV) transmittance have been synthesized following a sol-gel route starting from fluorinated alkoxide precursors. Matrix dehydration and fluorination have been investigated by Raman, IR, and refractive index measurements. The results show that, during the densification step, the residual hydroxyl and fluorine content can be controlled by governing the kinetic equilibrium between matrix collapse and fluorine evolution. This highlights the pivotal role of in situ reactions of fluorine-containing molecular precursors in the networking mechanism of a sol-gel material after thermal activation. Superior VUV transmittance and radiation hardness with respect to pure commercial silica and undoped sol-gel silica have been confirmed by synchrotron light absorption measurements before and after X-ray exposure. These properties make the material very attractive for applications in VUV photolithography technologies and optical fibers, especially for use in environments with a high level of ionizing radiation, such as spacecrafts and nuclear power plants.

We have investigated the structural modifications that occur concomitantly with the generation of optical anisotropy in the binary glass with nominal starting composition 0.51(CaO)0.49(P2O5) as a result of hot-extrusion processes. Micro-Raman and X-ray-fluorescence micro-analysis have been used to map the structure and composition along the directions parallel and orthogonal to the extrusion axis, with respect to which we have detected birefringence and refractive index modifications up to 10-3. The results show an annular region, midway between the axis and the outer side, in which Ca is slightly depleted and the phosphate chains are shortened and packed through crosslinking sites in anisotropic arrangement. © 2011 Published by Elsevier B.V.

Second harmonic generation properties have been studied in 23 K2O · 27Nb2O5 · 50 SiO2 glass subjected to thermal poling. The poling-induced optical nonlinearity, with χ(2) = 3.8 pm/V, has been related to structural modifications within a surface layer of a few microns on the anode side, as evidenced by means of confocal micro-Raman mapping along the sample thickness. The data indicate that the structural changes result from a charge transport process that causes network modifications in an alkali depleted layer whose thickness is comparable with that of the non-linear region. The Raman data also indicate that in the alkali depleted layer the network polymerization degree increases as a consequence of ion migration. The origin of the nonlinearity and the mechanisms activated by poling are discussed. The mechanism of non-bridging-oxygen to bridging-oxygen bond switching is proposed to explain ion migration and the subsequent structural changes in the glass. © 2009 Elsevier B.V. All rights reserved.

Elemental Ge nanophases are obtained in silica starting from a sol-gel synthesis. The process comprises the preparation of silica xerogel doped by Ge(IV), substituting for Si(IV) in the oxide network, followed by reduction and phase separation during the sintering process by reaction with H-2 or CO. X-ray diffraction, Raman spectroscopy and high resolution transmission electron microscopy show that reactions with H-2 give rise in the porous silica network to nanometer-sized crystallization of elemental cubic germanium. (c) 2007 Elsevier Ltd. All rights reserved.

Seven hydrocarbonoclastic new bacterial isolates were isolated from dredged sediments of a river estuary in Italy. The sediments were contaminated by shipyard activities since decades, mainly ascribable to the exploitation of diesel oil as the fuel for recreational and commercial navigation of watercrafts. The bacterial isolates were able to utilize diesel oil as sole carbon source. Their metabolic capacities were evaluated by GC-MS analysis, with reference to the depletion of both the normal and branched alkanes, the nC18 fatty acid methyl ester and the unresolved complex mixture of organic compounds. They were taxonomically identified as different species of Stenotrophomonas and Pseudomonas spp. by the combination of amplified ribosomal DNA restriction analysis (ARDRA) and repetitive sequence-based PCR (REP-PCR) analysis. The metabolic activities of interest were analyzed both in relation to the single bacterial strains and to the combination of the latter as a multibacterial species system. After 6 days of incubation in mineral medium with diesel oil as sole carbon source, the Stenotrophomonas sp. M1 strain depleted 43-46 % of Cn-alkane from C28 up to C30, 70 % of the nC18 fatty acid methyl ester and the 46 % of the unresolved complex mixture of organic compounds. On the other hand, the Pseudomonas sp. NM1 strain depleted the 76 % of the nC18 fatty acid methyl ester, the 50 % of the unresolved complex mixture of organic compounds. The bacterial multispecies system was able to completely deplete Cn-alkane from C28 up to C30 and to deplete the 95 % of the unresolved complex mixture of organic compounds. The isolates, either as single strains and as a bacterial multispecies system, were proposed as candidates for bioaugmentation in bio-based processes for the decontamination of dredged sediments.

Light emission of nanocrystals (NCs) can depend not only on NC size but also – and even more importantly in wide-band-gap NCs – on the occurrence of optically active sites, such as donor–acceptor pairs (DAPs). Here, we demonstrate that controlling the thermo-chemical conditions of NC nucleation when NCs are forming in a solid host – an approach often used for driving NC size dispersion – can be an innovative strategy for tailoring DAP population. Our data show that light emission from DAP recombination and decay in defect sites can be controlled in γ-Ga2O3 NCs in alkali-germanosilicate glass – a prototypal oxide-in-oxide nanostructured system – by oxygen and gallium vacancy formation during nucleation. Time-resolved UV-excited photoluminescence, combined with differential scanning calorimetry, X-ray diffraction, and transmission electron microscopy, reveal how nucleation pretreatment determines, besides NC size and concentration, also the DAP number via promotion of acceptor formation or their passivation during interaction with the host. The results envisage the possibility of nucleation-based design of light-emitting NCs in a wide range of oxide systems.

We present a novel strategy for the synthesis of pure and Eu-doped γ-Ga2O3 nanoparticles with an in situ organic capping resulting from a non-aqueous solution-based benzyl alcohol synthesis route. Photoluminescence spectroscopy highlights the concomitant benzoate-related and γ-Ga2O3 exciton-like Eu3+ excitations in the UV, and a blue emission superimposed onto γ-Ga2O3 donor–acceptor recombination, ascribable to organic moieties different from benzoate.

Wide-bandgap nanocrystals are an inexhaustible source of tuneable functions potentially addressing most of the demand for new light emitting systems. However, the implementation of nanocrystal properties in real devices is not straightforward if a robust and stable optical component is required as a final result. The achievement of efficient light emission from dense dispersions of Ga-oxide nanocrystals in UV-grade glass can be a breakthrough in this regard. Such a result would permit the fabrication of low cost UV-to-visible converters for monitoring UV-emitting events on a large-scale - from invisible hydrogen flames to corona dispersions. From this perspective, γ-Ga₂O₃ nanocrystals are developed by phase separation in Ga-alkali-germanosilicate glasses, obtaining optical materials based on a UV transparent matrix. Band-to-band UV-excitation of light emission from donor-acceptor pair (DAP) recombination is investigated for the first time in embedded γ-Ga₂O₃. The analysis of the decay kinetics gives unprecedented evidence that nanosized confinement of DAP recombination can force a nanophase to the efficient response of exactly balanced DAPs. The results, including a proof of concept of UV-to-visible viewer, definitely demonstrate the feasibility of workable glass-based fully inorganic nanostructured materials with emission properties borrowed from Ga₂O₃ single-crystals and tailored by the nanocrystal size.

In the present study, the quality of effluents from a conventional wastewater treatment plant in Italy has been analyzed. Residual level of contamination by 4-n-nonylphenol, mono- and di-ethoxylated nonylphenols has been recorded in the effluents that resulted to be also phytotoxic and genotoxic. The possibility of exploiting phytoremediation as a sustainable tertiary treatment for the depletion of the priority pollutants and for the reduction in the residual toxicity has been verified at mesocosm scale. The phyto-based treatment has been performed by the exploitation of Phragmites australis by either a bacterial-assisted and not assisted approach. In relation to the bacterial-assisted approach, two new bacterial strains, capable of using the nonylphenols as a sole carbon source, have been isolated. One was identified as a plant growth-promoting rhizobacteria (PGPR) belonging to the Stenotrophomonas species, and the second one was classified as a Sphingobium species strain. Both strains were independently bioaugmented in the P. australis rhizosphere. In relation to the not assisted approach, the phyto-based process determined 87, 70 and 87 % for 4-n-nonylphenol, mono-ethoxylated nonylphenols and di-ethoxylated nonylphenols, respectively. The toxicological assessment of the process evidenced the complete depletion of either the phytotoxicity or the genotoxicity of the treated effluents. With reference to the bacterial-assisted approach, the PGPR Stenotrophomonas species strain resulted to be capable of significantly increasing the efficiency of the phyto-based process in nonylphenol depletion up to 88 % for the 4-n-nonylphenol, 84 % for the mono-ethoxylated nonylphenol and 71 % for the di-ethoxylated nonylphenol.

Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic contaminants causing hazards to organisms including humans. The objective of the study was to validate the vegetation of dredged sediments withPhragmites australisas an exploitable biostimulation approach to accelerate the depletion of PAHs in nitrogen spiked sediments. Vegetation withPhragmites australisresulted in being an efficient biostimulation approach for the depletion of an aged PAHs contamination (229.67±15.56 μg PAHs/g dry weight of sediment) in dredged sediments.Phragmites australisaccelerated the oxidation of the PAHs by rhizodegradation. The phytobased approach resulted in 58.47% of PAHs depletion. The effects of the treatment have been analyzed in terms of both contaminant depletion and changes in relative abundance of the metabolically active Gram positive and Gram negative PAHs degraders. The metabolically active degraders were quantified both in the sediments and in the root endospheric microbial community. Quantitative real-time PCR reactions have been performed on the retrotranscribed transcripts encoding the Gram positive and Gram negative largeαsubunit (RHDα) of the aromatic ring hydroxylating dioxygenases. The Gram positive degraders resulted in being selectively favored by vegetation withPhragmites australisand mandatory for the depletion of the six ring condensed indeno[1,2,3-cd]pyrene and benzo[g,h,i]perylene.

Summary In this paper we analysed the endogenous IAA levels in carrot cell cultures and in cell culture medium. Free IAA and its conjugates (esters and amides) were measured in cell cultures exposed to different concentrations of 2,4-D (nil, 2,3 and- 92 μmol/L). The three culture conditions determine different physiological conditions of the cell cultures: somatic embryogenesis, unorganised growth and growth under stress, respectively. The results indicate that these two types of IAA conjugates account for 60–70 % of total IAA and buffer the variations of free IAA in a sequential manner. Free IAA is in a steady state relationship with the ester conjugates and the increased synthesis of IAA is initially buffered by IAA-amide. When a certain threshold (750 ng/g) is reached inside the cell by the amide, further increments are buffered by ester IAA. Another result coming from this analysis is that the presence of tryptophan alone in the culture medium is sufficient to sustain, metabolically as well as physiologically, the conditions of proliferation, shifting the state of the cell culture from somatic embryogenesis to unorganised growth.

We have recently reported that besides the most abundant form epsilonS1, there exists another human secretory epsilon H chain isoform, epsilonS2, resulting from alternative splicing in the epsilonCH4 exon. Using a specific antibody targeted to the epsilonS2-specific C-terminal tailpiece, we now show that this second secretory IgE isoform (IgE-S2) is constitutively co-expressed with the classical secretory IgE-S1 by human myeloma cells. The epsilonS2 variant was also detected in tonsils and in the serum of three non-atopic donors, but was absent in the vast majority of sera of both atopic and non-atopic individuals tested, indicating rare serum expression. IgE-S2 is capable of binding to cells expressing Fc epsilonRI, the high-affinity receptor for IgE. Analysis of intracellular tyrosine phosphorylation signal, degranulation, and rate of receptor internalization suggest a quantitatively lower response by IgE-S2 compared to IgE-S1. The modest differences observed do not appear to overall affect the degranulation competency of IgE-S2, but suggest that the unique structure of the epsilonS2 tailpiece can exert an effect on the interaction with the alpha chain of Fc epsilonRI.

Unlike other immunoglobulin isotypes, the human C epsilon gene generates by alternative splicing two types of secretory and two types of membrane epsilon chains. The two secreted epsilon heavy chains, epsilon(S1) and epsilon(S2), differ only in the sequence of the last eight C-terminal amino acids, being epsilon(S2) six amino acids longer. The two types of membrane isoforms differ in the extracellular membrane proximal domain, with the longer variant, epsilon(mL), containing 52 extra amino acids which are absent in the shorter epsilon(mS) isoform.We wished to produce quality antibody reagents that specifically detect epitopes that are epsilon isoform-specific.Short sequences of seven or ten amino acids were chosen as target epitopes and expressed as part of the highly immunogenic loops of deletion variants of engineered Flock House Virus capsid protein RNA2. Chimeric proteins were expressed in E. coli, and used to immunize rabbits. Antisera were screened by immunoblotting of purified IgE isoforms expressed by murine transfectomas.Chimeric proteins expressing epsilon isoform-specific epitopes proved to be strong immunogens in vivo and induced highly specific rabbit antisera. Two antisera so obtained recognize specifically the IgE-S2 isoform. A third one recognizes the long membrane variant m(L)IgE and a fourth one detects an epitope specific to m(S)IgE.Here we describe a simplified and efficient protocol of immunization which does not require peptide synthesis and conjugation to carrier protein. Our results show that short peptides of unknown immunogenicity, when genetically introduced into the modified Flock House Virus epitope display system, successfully induced IgE isoform-specific polyclonal antisera in rabbits. These are valuable tools to specifically identify secretory and membrane isoforms of human IgE, and the method is potentially applicable to other variant isoforms or mutants of a given protein.

Endosperm of Sechium edule seed was incubated with [U-14C]adenine and [13C]mevalonic acid for 17 h. Following incubation, cytokinins were extracted and purified by HPLC. Using GC-MS, incorporation of [13C]MVA into isopentenyladenine and zeatin riboside was demonstrated. This is the first unequivocal demonstration of cytokinin biosynthesis in a normal plant tissue because precursors incorporation into cytokinins was demonstrated by MS. The significance of these results is also discussed in relation to a possible mononucleotide-independent pathway of cytokinin biosynthesis.

Potato seed tubers may suffer from premature sprouting during storage, thus limiting their suitability for cultivation. Commonly used sprout suppressant treatments negatively affect but viability and therefore a reliable method to inhibit bud development must still be found for seed tubers. The monoterpene carvone ((S)-(+)-carvone) was tested in small scale experiments. The vapour of this compound fully inhibited bud growth of tubers cv. Monalisa stored at 23°C without affecting bud viability throughout 6 months of treatment. The most effective range of carvone vapour concentrations was between 0.34 and 1.06 μmol mol−1. With these qualities we can expect carvone to become a suitable sprout suppressant for seed tubers.

International audience; Nanoparticles in amorphous oxides are a powerful tool for embedding a wide range of functions in optical glasses, which are still the best solutions in several applications in the ever growing field of photonics. However, the control of the nanoparticle size inside the host material is often a challenging task, even more challenging when detrimental effects on light transmittance have to be avoided. Here we show how the process of phase separation and subsequent nanocrystallization of a Ga-oxide phase can be controlled in germanosilicates – prototypal systems in optical telecommunications – starting from a Ga-modified glass composition designed to favour uniform liquid–liquid phase separation in the melt. Small angle neutron scattering data demonstrate that nanosized structuring occurs in the amorphous as-quenched glass and gives rise to initially smaller nanoparticles, by heating, as in a secondary phase separation. By further heating, the nanophase evolves with an increase of nanoparticle gyration radius, from a few nm to a saturation value of about 10 nm, through an initial growing process followed by an Ostwald ripening mechanism. Nanoparticles finally crystallize, as indicated by transmission electron microscopy and X-ray diffraction, as γ-Ga2O3 – a metastable gallium oxide polymorph. Infrared reflectance and photoluminescence, together with the optical absorption of Ni ions used as a probe, give an indication of the underlying interrelated processes of the structural change in the glass and in the segregated phase. As a result, our data give for the first time a rationale for designing Ga-modified germanosilicates at the nanoscale, with the perspective of a detailed nanostructuring control.

Summary Tubers cv. Monalisa were analysed to determine the content of abscisic acid (c-t-(+)ABA) and related metabolites in three tuber parts (eyes, sub-eye tissues and pith). Analyses were performed from the last period of tuber growth until sprouting under two different storage temperatures (3 °C and 23 °C). ABA content rises in eyes and sub-eye tissues as sprouting approaches, regardless of storage temperature. Dihydrophaseic acid is the main ABA metabolite while phaseic acid was not detected, probably because of its further metabolization to DPA. ABA-glucose ester concentrations are generally low in all tissues except in eyes before harvest. The results are discussed in relation to the current hypotheses on the role of ABA in the control of potato tuber dormancy.

A spectroscopic protocol is proposed to implement confocal microfluorescence imaging to the analysis of microinhomogeneity in the nanocrystallization of the core of fibers belonging to a new kind of broadband fiber amplifier based on glass with embedded nanocrystals. Nanocrystallization, crucial for achieving an adequate light emission efficiency of transition metal ions in these materials, has to be as homogeneous as possible in the fiber to assure optical amplification. This requirement calls for a sensitive method for monitoring nanostructuring in oxide glasses. Here we show that mapping microfluorescence excited at 633 nm by a He-Ne laser may give a useful tool in this regard, thanks to quasi-resonant excitation of coordination defects typical of germanosilicate materials, such as nonbridging oxygens and charged Ge-O-Ge sites, whose fluorescence are shown to undergo spectral modifications when nanocrystals form into the glass. The method has been positively checked on prototypes of optical fibers—preventively characterized by means of scanning electron microscopy and energy dispersive spectroscopy—fabricated from preforms of Ni-doped Li2O-Na2O-Sb2O3-Ga2O3-GeO2-SiO2 glass in silica cladding and subjected to heat treatment to activate gallium oxide nanocrystal growth. The method indeed enables not only the mapping of the crystallization degree but also the identification of drawing-induced defects in the fiber cladding.

The development of integrated photonics and lab-on-a-chip platforms for environmental and biomedical diagnostics demands ultraviolet electroluminescent materials with high mechanical, chemical and environmental stability and almost complete compatibility with existing silicon technology. Here we report the realization of fully inorganic ultraviolet light-emitting diodes emitting at 390 nm with a maximum external quantum efficiency of ~0.3%, based on SnO(2) nanoparticles embedded in SiO(2) thin films obtained from a solution-processed method. The fabrication involves a single deposition step onto a silicon wafer followed by a thermal treatment in a controlled atmosphere. The fully inorganic architecture ensures superior mechanical robustness and optimal chemical stability in organic solvents and aqueous solutions. The versatility of the fabrication process broadens the possibility of optimizing this strategy and extending it to other nanostructured systems for designed applications, such as active components of wearable health monitors or biomedical devices.

The present work reports on the investigation of oxidation states, local symmetry, and optical properties of manganese and iron species in natural cordierite (Mg, Fe) 2 Al 4 Si 5 O 18 , by means of energy-dispersive X-ray fluorescence, electron paramagnetic resonance (EPR), photoluminescence (PL) and optical absorption techniques. In particular, specific EPR characteristics show the presence of distinct Mn 2+ octahedral sites in the crystal lattice, and a small amount of Mn 4+ ions in tetrahedral sites. The absence of EPR signal ascribable to Mn 4+ in octahedral sites turns out to be consistent with the lack of narrow PL lines from d 3 ions in octahedral crystal field (CF). Evidence of Mn 3+ in octahedral sites is instead found in steady-state and time-resolved PL measurements. EPR spectra give further details on iron site occupancy, showing the occurrence of Fe 3+ ions in octahedral sites. Characteristics ascribable to all the identified metal species have been found in the optical absorption spectrum or in the PL excitation spectrum, as arising from the expected CF transitions of Fe 2+ , Fe 3+ , Mn 2+ , Mn 3+ , and Mn 4+ ions. Interestingly, the results show a polarization-dependent correlation between the manganese luminescence and the pleochroic absorption band at about 17,000 cm −1 . This result reveals a pleochroic contribution from the Mn 3+ spin-allowed 5 E→ 5 T 2 transition under the visible pleochroic band attributed to Fe 2+ (oct)→Fe 3+ (tet) transitions.

The target of taking advantage of the near-infrared light-emission properties of nickel ions in crystals for the design of novel broadband optical amplifiers requires the identification of suitable nanostructured glasses able to embed Ni-doped nanocrystals and to preserve the workability of a glass. Here we show that Ni doping of Li2O‐Na2O‐Ga2O3‐GeO2‐SiO2 glass (with composition 7.5:2.5:20:35:35 and melting temperature 1480 ◦ C, sensibly lower than in Ge-free silicates) enables the selective embedding of nickel ions in thermally grown nanocrystals of spinel-like gallium oxide. The analysis of transmission electron microscopy and x-ray diffraction data as a function of Ni-content (from 0.01 to 1 mol%) indicates that Ni ions promote the nanophase crystallization without affecting nanoparticle size (∼ 6n m) and concentration (∼4 × 10 18 cm −3 ). Importantly, as shown by optical absorption spectra, all nickel ions enter into the nanophase, with a number of ions per nanocrystal that depends on the nanocrystal concentration and ranges from 1 to 10 2 . Photoluminescence data indicate that fast non-radiative decay processes become relevant only at mean ion‐ion distances shorter than 1.4 nm, which enables the incorporation of a few Ni ions per nanoparticle without too large a worsening of the light-emission efficiency. Indeed, at 0.1 mol% nickel, the room temperature quantum yield is 9%, with an effective bandwidth of 320 nm. (Some figures may appear in colour only in the online journal)

The nucellus is a maternal tissue that feeds the developing embryo and the secondary endosperm. During seed development the cells of the nucellus suffer a degenerative process early after fertilization as the cellular endosperm expands and accumulates reserves. Nucellar cell degeneration has been characterized as a form of developmentally programmed cell death (PCD). In this work we analysed the role of the endosperm as main regulator of nucellus PCD. We demonstrated that endosperm produces high amount of ethylene, nitric oxide and indoleacetic acid. We examined the role of these small and diffusible signalling molecules in the regulation of nucellus PCD and we tried to elucidate how they can cooperate and regulate each other into the endosperm. We showed that ethylene acts a positive regulator of nucellus PCD and its synthesis can be in part induced by nitric oxide. High levels of IAA were detected both in the endosperm and in dying nucellus but this hormone is not directly involved in the execution of PCD.

We present the results of the analysis of the ultraviolet (UV) absorption edge of fluorine-modified sol-gel silica. UV transmission data, obtained by means of synchrotron radiation, have been analyzed in the spectral range 7.5–8.5 eV, with a spectral resolution of about 10 meV. Data on silica samples with different F content (from 0 to few 10 − 1 mol%) have been analyzed and compared with literature data on quartz and pure synthetic commercial silica. The analysis allows us to discriminate between the effects of the fluorine addition and those ascribable to structural peculiarities of the sol-gel networking. The estimated Urbach energy E U ( T = 0) ranges between 45 and 55 meV, higher that in crystalline quartz and lower than in commercial synthetic silica. The study of the temperature dependence of E U ( T ) shows that the fluorine modification of the silica network causes the lowering of the static disorder and the widening of the energy gap. However, there is also a relevant effect of the production process, since sol-gel silica samples show lower E U values with respect to other types of silica, quite independently of the fluorine content. The analysis of the Raman spectra however shows that the starting amount of fluorine-modified molecular precursor influences the network condensation process, independently of the final fluorine content into the matrix.

Silica thin films with embedded SnO 2 nanoparticles have been grown on transparent substrates by the sol–gel method. Tin dioxide crystals with cassiterite structure are semiconductors with a wide band gap of ~ 3.6 eV. Optical absorption spectroscopy in the near ultraviolet–visible range has been exploited to probe nanostructuring features of such nanocrystals. The results show that the sintering conditions modify crystallite mean size and enable the occurrence of quantum confinement effects. The outcome is in accordance with transmission electron microscopy data conducted on analogous bulk samples.

Grains of wheat ( Triticum durum Desf. cv. Cappelli) were collected at different stages of maturation. To test whether the response to desiccation injury is correlated with physiological stage and/or water content, one lot of grains at each stage was artificially dried until its water content was comparable to that of the subsequent stage. Several stress parameters were analysed in embryos isolated from naturally-and artificially-dried grains. In particular, the content of dehydrins, hydrogen peroxide and the activity of ribonucleases and of antioxidant enzyme were studied. Neutral ribonucleases, unlike acidic ones, seemed to be correlated with grain water content. In parallel with these analyses the presence of dehydrins was also examined. Dehydrin accumulation was found to vary with drying rate, and more isoforms of dehydrin were present in artificially dried than in naturally-dried grains. Artificial drying resulted in accumulation of hydrogen peroxide, while the content of this molecule was much lower in embryos from naturally fully-ripened grains. While the activities of ascorbate peroxidase (APX, EC 1.11.1.11), dehydroascorbate reductase (DHAR, EC 1.8.5.1), glutathione reductase (GR, EC 1.6.4.2), and glutathione peroxidase (GPX, EC 1.11.1.9), were generally higher early in maturation, the activity of catalase (CAT, EC 1.11.1.6) increased in mid-maturation and decreased in fully-ripe embryos. Different protective mechanisms seem to act in combination but their relative importance changes as maturation progresses and in response to the drying method.

The nucellus is a maternal tissue that feeds the developing embryo and the secondary endosperm. During seed development the cells of the nucellus suffer a degenerative process early after fertilization as the cellular endosperm expands and accumulates reserves. Nucellar cell degeneration has been characterized as a form of developmentally programmed cell death (PCD). In this work we show that nucellus PCD is accompanied by a considerable production of both nitric oxide and hydrogen peroxide (NO and H(2)O(2)). Interestingly, each of the two molecules is able to induce the production of the other and to cause cell death when applied to a living nucellus. We show that the induced cell death has features of a PCD, accompanied by profound changes in the morphology of the nuclei and by a massive degradation of nuclear DNA. Moreover, we report that NO and H(2)O(2) cause an induction of caspase-like proteases previously characterized in physiological nucellar PCD.

Synthetic dyes are recalcitrant to degradation and toxic to different organisms. Physical-chemical treatments of textile wastewaters are not sustainable in terms of costs. Biological treatments can be more convenient and the lig-nin-degrading extracellular enzymatic battery of basidiomycetes are capable to discolor synthetic dyes. Many basidi-omycetes are edible mushrooms whose industrial production generates significant amount of spent mushroom substrate (SMS) with residual high levels of lignin-degrading extracellular enzymatic activities. We have demon-strated that the low cost organic substrate, the SMS deriving from the cultivation of the basidiomycetes Pleurotus ostreatus, is able to discolor anthraquinonic, diazo and monoazo-dyes when incubated in dying chromo-reactive and chromo-acid baths containing surfactants and anti-foams, where the concentrations of the different dyes are exceeding the one recovered in the corresponding wastewaters. Laccase was the lignin-degrading extracellular enzyme involved in the discolouring process. The exploitation of the low cost SMS in the treatment of textile wastewaters is proposed. Accordingly, a toxicological assessment, based on a cyto-toxicity test on a human amnion epithelial cell line (WISH) and the estimation of the germination index (GI%) of Lactuca sativa, Cucumis sativus and Sorghum bicolor, has been performed, showing the loss of toxicity of the chromo-baths after being discoloured by the SMS.

Photoluminescence in fluorine-modified Sn-doped silica has been analyzed by means of synchrotron radiation in the UV and vacuum-UV, from 120 to 330 nm, looking at the optical activity of oxygen-deficient-centers ODC(II) in Sn-substituted cationic sites. The comparison between F-modified Sn-doped samples and previous data on F-free Sn-doped material evidences differences in the intensity of the 3.2 eV emission band excited at 3.7 eV, and in the thermal dependence of the intensity of this emission excited via intersystem crossing. The role of fluorine in modifying the optical activity of ODC(II) and in the SnO2 clustering is discussed, showing that an efficient excitation transfer may be activated from SnO2 to the Sn-variant of ODC(II). © 2009 Elsevier B.V. All rights reserved.

Silica samples with embedded SnO2 nanoparticles have been produced by sol-gel method with a synthesis modified by the introduction of fluorinated silicon precursors. The structural features of silica network and SnO2 nanophase have been mapped inside the samples by means of confocal micro-Raman scattering spectroscopy. The results show that the detection of residual fluorine into the matrix as Si-F groups is accompanied by network dehydration, by intensity depletion of the D2 peak assigned to three-member rings of coordinated tetrahedra, and by SnO2 nanoparticles with much larger sizes than in fluorine-free material. © 2009 Elsevier B.V. All rights reserved.

Plant growth regulators are involved in the control of potato (Solanum tuberosum) tuber dormancy. Evidence concerning the role of IAA is controversial; we therefore investigated its role by analyzing two cultivars with varying lengths of dormancy. We examined the time course of free and conjugated IAA in tuber tissue isolates from the final stages of tuber growth to the end of dormancy, the distribution of free IAA in tuber tissues by in situ analysis, and the biosynthesis of the hormone by feeding experiments. The time course of free IAA showed marked differences between the examined cultivars, although the concentration of the auxin generally was the highest at the early stages of tuber dormancy. Immunodetection showed a similar pattern of IAA distribution in both genotypes: in dormant buds from freshly harvested tubers, the free hormone accumulated mostly in apical meristem, leaf and lateral bud primordia, and differentiating vascular tissues underlying the apical meristem, while at the end of the storage period only axillary bud primordia from growing buds displayed appreciable auxin levels. Feeding experiments indicated that changes in IAA biosynthesis rate were a major cause of auxin variation in buds. In both cultivars, dormancy apparently ceased when free IAA fell below a threshold value. Despite this, our data led us to conclude that IAA would not be directly responsible for inhibiting sprouting. Instead, auxin might shorten dormancy, in a cultivar-dependent manner, by enhancing early developmental processes in buds, ultimately leading to dormancy termination.