Growing CeO2_2 Nanoparticles within the Nano-Porous Architecture of the SiO2_2 Aerogel

In this study, new CeO$_2$-SiO$_2$ aerogel nanocomposites obtained by controlled growth of CeO$_2$ nanoparticles within the highly porous matrix of a SiO$_2$ aerogel are presented. The nanocomposites have been synthesized via a sol-gel route, employing cerium (III) nitrate as the CeO$_2$ precursor and selected capping agents to control the growth of the CeO$_2$ nanoparticles, which occurs during the supercritical drying of the aerogels. Samples with different loading of the CeO$_2$ dispersed phase, ranging from 5 to 15%, were obtained. The nanocomposites showed the morphological features typical of the SiO$_2$ aerogels such as open mesoporosity with surface area values up to 430 m$^2$·g$^{-1}$. TEM and XRD characterizations show that nanocrystals of the dispersed CeO$_2$ nanophase grow within the aerogel already during the supercritical drying process, with particle sizes in the range of 3 to 5 nm. TEM in particular shows that the CeO$_2$ nanoparticles are well distributed within the aerogel matrix. We also demonstrate the stability of the nanocomposites under high temperature conditions, performing thermal treatments in air at 450 and 900°C. Interestingly, the CeO$_2$ nanoparticles undergo a very limited crystal growth, with sizes up to only 7 nm in the case of the sample subjected to a 900°C treatment

Characterization of FeOOH nanoparticles and amorphous silica matrix in an FeOOH-Sio 2 nanocomposite

A nanocomposite with an FeOOH/SiO2ratio equal to 17.7 wt% and the pertinent matrix, obtained by etching away the nanoparticles through reaction with hydrochloric acid, were investigated by XRD, TGA-DTA, heliostereopicnometry, BET, and TEM techniques. The study shows the presence in the nanocomposite of ferrihydrite nanoparticles phase with average dimensions around 4 nm. The FeOOH nanoparticles structure was analyzed by synchrotron X-ray diffraction data using the distribution difference curve method. The porous structure of the matrix resulting by etching away the nanoparticles differs significantly from that of a pureSiO2sample obtained by hydrolysis of TEOS under the same operative conditions followed in the nanocomposite preparation

Design of Dual-Emitting Nonaromatic Fluorescent Polymers through Thermal Processing of l-Glutamic Acid and l-Lysine

Fluorescence emission of proteins containing aromatic groups and conjugated bonds is generally associated with light absorption in the ultraviolet range, around 185-320 nm. Photoluminescence in nonaromatic biopolymers, however, has also been observed in amyloid-like structures and polymers derived from l-lysine and glycine. Here, we show, for the first time, that branched polymers obtained through thermal copolymerization of two nonaromatic amino acids, l-lysine and l-glutamic acid, exhibit two-color centers with relative absorptions in the visible range. Thermal homopolymerization of l-lysine or l-glutamic acid gives rise to the formation of branched polyglutamic acid and polylysine with a single fluorescence emission peaking at around 450 nm. The coreaction of the two amino acids produces instead a branched peptide-like polymer with a new emission centered at around 380 nm. The structures of the copolymers were studied by differential scanning calorimetry, in situ temperature-resolved FTIR, NMR, and TEM spectroscopy techniques. The optical properties were investigated by UV-vis and fluorescence spectroscopy. The double emission can be correlated with two different intramolecular charge transfer processes between the polymer backbone and the oppositely charged moieties of the two precursor side chains, Lys and Glu, which are at the origin of near-UV fluorescence

MF59-adjuvanted H1N1v vaccine

Summary Background:  When H1N1v vaccines become widely available, most elderly subjects will have already received their seasonal influenza vaccination. Adults seeking H1N1v vaccination may be offered seasonal vaccine as well. We investigated prior seasonal vaccination in adult and elderly subjects, and concomitant vaccination with seasonal vaccine in adults, on the tolerability and immunogenicity of the Novartis MF59-adjuvanted H1N1v vaccine, Focetria®. Methods:  A total of 264 adult (four groups) and 154 elderly (three groups) subjects were enrolled. The licensure study cohorts for plain (Agrippal®) and MF59-adjuvanted (Fluad®) 2009–2010 seasonal vaccines were invited to receive Focetria 3 months later, with seasonal vaccine–naive controls, and adults who received Focteria and seasonal vaccine concomitantly. Immunogenicity of all vaccines was assessed by haemagglutination inhibition on Days 1 and 22, safety and reactogenicity were monitored using patient diaries. Results:  All adult and elderly groups met all the European CHMP licensing criteria for H1N1v, as did adults receiving concomitant seasonal vaccine for the three seasonal strains. Vaccines were generally well tolerated, causing no SAEs, and profiles typical of MF59-adjuvanted vaccines. Reactions were mainly mild or moderate and transient, and unaffected by prior or concomitant seasonal vaccination except for elderly subjects previously given MF59-adjuvanted seasonal vaccine, whose reaction rates to Focetria were about half those seen in groups receiving their first MF59 vaccine. Conclusion:  One dose of MF59-adjuvanted H1N1v vaccine met the licensure criteria for adult and elderly subjects 3 months after seasonal vaccination, or concomitantly with seasonal vaccine in adults, without impacting the tolerability or immunogenicity of either vaccine, thus facilitating mass influenza immunisation campaigns

graphene mediated surface enhanced raman scattering in silica mesoporous nanocomposite films

Highly performing mesoporous nanocomposite films with embedded exfoliated graphene and gold nanoparticles display a significant enhancement of G-SERS properties

Main roads to melanoma

The characterization of the molecular mechanisms involved in development and progression of melanoma could be helpful to identify the molecular profiles underlying aggressiveness, clinical behavior, and response to therapy as well as to better classify the subsets of melanoma patients with different prognosis and/or clinical outcome. Actually, some aspects regarding the main molecular changes responsible for the onset as well as the progression of melanoma toward a more aggressive phenotype have been described. Genes and molecules which control either cell proliferation, apoptosis, or cell senescence have been implicated. Here we provided an overview of the main molecular changes underlying the pathogenesis of melanoma. All evidence clearly indicates the existence of a complex molecular machinery that provides checks and balances in normal melanocytes. Progression from normal melanocytes to malignant metastatic cells in melanoma patients is the result of a combination of down- or up-regulation of various effectors acting on different molecular pathways

Mesoscale organization of titania thin films enables oxygen sensing at room temperature

The application of titania materials to gas sensing devices based on thin films are of limited utility because they only operate at a high working temperature and exhibit in general a low sensitivity. To overcome these constraints, a new type of oxygen sensor based on mesoporous titania thin films working at room temperature under UV irradiation has been developed. The increased density of charge carriers induced by the photoconductive effect, has been used to enhance the sensitivity of the thin oxide layers. Mesostructured titania films have been prepared via self-assembly and thermal processing to remove the organic template obtaining anatase nanocrystals. The mesoporous films show a striking decrease of the current in the presence of oxygen that acts as an electron scavenger. Mesoporous samples exhibit a much higher response with respect to dense titania, due to the higher surface area and the larger number of surface defects.RAS is acknowledged for funding this project through CRP 30 L.R. 7/2007 ‘‘Bando Capitale Umano ad Alta Qualificazione annualita` 2015’’. This work was partially supported by the project ‘‘Mi ADATTI E L’ABBATTI’’- INSTM-Regione Lombardia project INSTMRL6

Magnetic Study of CuFe2O4-SiO2 Aerogel and Xerogel Nano-composites

CuFe2O4 is an example of ferrites whose physico-chemical properties can vary greatly at the nanoscale. Here, sol-gel techniques are used to produce CuFe2O4-SiO2 nanocomposites where copper ferrite nanocrystals are grown within a porous dielectric silica matrix. Nanocomposites in the form of both xerogels and aerogels with variable loadings of copper ferrite (5 wt%, 10 wt% and 15 wt%) were synthesized. Transmission Electron Microscopy and X-Ray Diffraction investigations showed the occurrence of CuFe2O4 nanoparticles with average crystal size ranging from a few nanometers up to around 9 nm, homogeneously distributed within the porous silica matrix, after thermal treatment of the samples at 900°C. Evidence of some impurities of CuO and -Fe2O3 was found in the aerogel samples with 10 wt% and 15 wt% loading. DC magnetometry was used to investigate the magnetic properties of these nanocomposites, as a function of the loading of copper ferrite and of the porosity characteristics. All the nanocomposites show blocking temperature lower than RT and soft magnetic features at low temperature. The observed magnetic parameters are interpreted taking into account the occurrence of size and interaction effects in an ensemble of superparamagnetic nanoparticles distributed in a matrix. These results highlight how aerogel and xerogel matrices give rise to nanocomposites with different magnetic features and how the spatial distribution of the nanophase in the matrices modifies the final magnetic properties with respect to the case of conventional unsupported nanoparticles

Thermally Stable Surfactant-Free Ceria Nanocubes in Silica Aerogel

Surfactant-mediated chemical routes allow one to synthesize highly engineered shape- and size-controlled nanocrystals. However, the occurrence of capping agents on the surface of the nanocrystals is undesirable for selected applications. Here, a novel approach to the production of shape-controlled nanocrystals which exhibit high thermal stability is demonstrated. Ceria nanocubes obtained by surfactant-mediated synthesis are embedded inside a highly porous silica aerogel and thermally treated to remove the capping agent. Powder X-ray Diffraction and Scanning Transmission Electron Microscopy show the homogeneous dispersion of the nanocubes within the aerogel matrix. Remarkably, both the size and the shape of the ceria nanocubes are retained not only throughout the aerogel syntheses but also upon thermal treatments up to 900 °C, while avoiding their agglomeration. The reactivity of ceria is measured by in situ High-Energy Resolution Fluorescence Detected - X-ray Absorption Near Edge Spectroscopy at the Ce L3 edge, and shows the reversibility of redox cycles of ceria nanocubes when they are embedded in the aerogel. This demonstrates that the enhanced reactivity due to their prominent {100} crystal facets is preserved. In contrast, unsupported ceria nanocubes begin to agglomerate as soon as the capping agent decomposes, leading to a degradation of their reactivity already at 275 °C

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors