New insights on the structural and optical properties of Ce–Ti mixed oxide nanoparticles doped with praseodymium

Nanostructured, doped Ce–Ti mixed oxides are potential materials for several applications such as pigments, catalysis, fuel cells, optical films, and gas sensors. In this article, a series of Pr-doped Ce–Ti oxides have been prepared by the solvothermal method. These compounds were characterized by XRD, Raman, N2 sorption, SEM and UV–VIS spectrophotometry techniques. The experimental results suggest that spherical morphology, nanocrystalline particles and high specific surface area (up to 180 m2 g-1) are achieved at low temperature with this free surfactant methodology. Under basic conditions, a single phase product is identified at high temperature (1000 ºC), while for acid or neutral conditions, secondary phases appear. Different colored materials, ranging from yellow to red, are obtained by varying the firing temperature, quantity of doping praseodymium and the pH of the reaction. The chemical stability of these oxides was tested in some industrial polymers or glazes

Die neuen Länder und ihre Verfassungen

The relationship between Rapid Automatized Naming (RAN) tasks and reading proficiency was first studied for English during the 70s, one finding being that children with dyslexia were slow and inconsistent in the RAN tasks. Later on, some studies have confirmed that RAN is the best predictor for transparent ortographies - and so of particular interest for Spanish. The research done so far on RAN and reading in Spanish is therefore reviewed here in order to draw conclusions for the diagnosis and treatment of reading difficulties. Our review shows that RAN is both a powerful early predictor of future reading outcomes and capable of discriminating between typical and poor readers. Being very easy to test, RAN is thus of great use in the diagnosis and prevention of reading disorders in Spanish

New insights on organosilane oligomerization mechanisms using ESI-MS and 29Si NMR

The use of electrospray ionization mass spectrometry (ESI-MS) in parallel with 29Si and 1H NMR to elucidate the aqueous speciation and temporal evolution of the organosilane methyldiethoxysilane (MDES) through hydrolysis and condensation processes is reported here. A suitable methodological approach for the monitoring of the oligomerization of MDES under different pH conditions has been developed revealing details on the particular oligomerization mechanism of this organosilan

Photonic and Nanobiophotonic Properties of Luminescent Lanthanide-Doped Hybrid Organic-Inorganic Materials

Research into lanthanide-doped organic–inorganic hybrid materials emerged in the 1990s with the development of interesting materials for optics: high efficiency and stable solid-state lasers, new fiber amplifiers and sensors, devices with upconversion, fast photochromic and non-linear responses, etc. Their interest relies on the possibility of combining properties of sol–gel host materials (shaping, tunable refractive index and mechanical properties, corrosion protection, specific adhesion, etc.) and the well-known luminescence of lanthanide ions (Ln). The fast development of photonic hybrids allowed the commercial exploitation of products with new or enhanced characteristics (megajoule pulsed Nd-YAG laser, protective coatings of glasses, screens or glasswares). However, recently, Ln-hybrid nanocomposites have found new applications in bio-sensors, bio-analytics and even clinical imaging diagnostics. These applications make use of the fluorescence properties of lanthanides that make luminescent hybrids ideal candidates for time-resolved fluoroimmunoassays, DNA hybridation assays, fluorescence imaging microscopy, or in vivo imaging. As a consequence, the goal of this review is twofold: (i) as a reminder of some general considerations that must be taken into account to design new optically active Ln-doped nanocomposites whatever the application field, and (ii) to show the most important advances achieved in the past years in different areas, paying special attention to bio-medical application

Anthocyanin composition and related pigments in strawberry

The anthocyanin composition of the strawberry has been object of various studies, but it is still not fully characterized. It is well known the presence af pelarganidin 3 - glucoside (Pg 3 -gluc) as major anthocyanin, usually accompanied of smaller proportions of pelargonidin 3- rutinoside (Pg 3 -rut) and cyanidin 3-glucosid e (Cy. 3- gluc).Comissão Europeia (Fundo Social Europeu) e Governo Português através do Programa PRODEP (III) - ref.ª 5.3/N/199.006/00-Doutoramento

Soluble ST2 levels and left ventricular structure and function in patients with metabolic syndrome

Background: A biomarker that is of great interest in relation to adverse cardiovascular events is soluble ST2 (sST2), a member of the interleukin family. Considering that metabolic syndrome (MetS) is accompanied by a proinflammatory state, we aimed to assess the relationship between sST2 and left ventricular (LV) structure and function in patients with MetS. Methods: A multicentric, cross-sectional study was conducted on180 MetS subjects with normal LV ejection fraction as determined by echocardiography. LV hypertrophy (LVH) was defined as an LV mass index greater than the gender-specific upper limit of normal as determined by echocardiography. LV diastolic dysfunction (DD) was assessed by pulse-wave and tissue Doppler imaging. sST2 was measured by using a quantitative monoclonal ELISA assay. Results: LV mass index (β=0.337, P<0 .001, linear regression) was independently associated with sST2 concentrations. Increased sST2 was associated with an increased likelihood of LVH [Exp (B)=2.20, P=0.048, logistic regression] and increased systolic blood pressure [Exp (B)=1.02, P=0.05, logistic regression]. Comparing mean sST2 concentrations (adjusted for age, body mass index, gender) between different LV remodeling patterns, we found the greatest sST2 level in the group with concentric hypertrophy. There were no differences in sST2 concentration between groups with and without LV DD. Conclusions: Increased sST2 concentration in patients with MetS was associated with a greater likelihood of exhibiting LVH. Our results suggest that inflammation could be one of the principal triggering mechanisms for LV remodeling in MetS

Lanthanide doped ZnS quantum dots dispersed in silica glasses: an easy one pot sol–gel synthesis for obtaining novel photonic materials

Silica glasses containing both ZnS quantum dots (QDs) and luminescent lanthanide ions are attractive candidates to develop new lighting displays, sensor devices or laser emitters. This work reports an easy sol–gel method to prepare Eu3+-doped and Eu3+,Mn2+-codoped ZnS nanocrystals dispersed in a transparent silica matrix. Semiconductor nanocrystals with an average size of 5–6 nm and exhibiting both cubic and hexagonal phases were obtained at low temperature. The luminescent interactions between ZnS QDs, Eu3+ and Mn2+ ions provided materials with different optical responses but also gave information about the organization of the different species in the nanocomposite. Indeed, Eu ions were found to be both dispersed within the silica and located at the surface of the nanochalcogenide, the latter providing a ZnS/Eu3+ energy transfer. Incorporation of Mn2+ into the ZnS lattice induced the appearance of defect states that enhance the blue luminescence of the nanocomposite. These results underline the sensitivity of optical processes to the nature and organization of the active species, which is of vital importance for the design of photonic material

Key insights on the structural characterization of textured Er2O3–ZrO2 nano-oxides prepared by a surfactant-free solvothermal route

Zirconia-mixed oxides can exhibit cubic fluorite and pyrochlore structure. Their discrimination is not easy in nanooxides with a crystal size close to that of a few unit cells. In this work, high resolution transmission electron microscopy (HRTEM) has been employed to provide key insights on the structural characterization of a nanometric and porous mixed Er2O3–ZrO2 oxide. The material was prepared by a simple template-free solvothermal route that provided nanocrystalline powders at low temperature (170 °C) with spherical morphology, and high surface area (∼280 m2 g−1). The porosity was mainly originated from the assembling of organic complexing agents used in the synthesis to limit the crystal growth and to control hydrolysis and condensation reaction rates. The samples were characterized by thermal analysis, X-ray diffraction, scanning electron microscopy and N2 adsorption measurements. A detailed study by HRTEM was conducted on microtomed samples. It was observed that the material was made of nanocrystals packed into spherical agglomerates. HRTEM simulations indicated that it is not possible to identify the pyrochlore phase in nanoparticles with diameter below 2 nm. In our samples, the analysis of the HRTEM lattice images by means of fast Fourier transform (FFT) techniques revealed well defined spots that can be assigned to different planes of a cubic fluorite-type phase, even in the raw material. Raman spectroscopy was also a powerful technique to elucidate the crystalline phase of the materials with the smallest nanoparticles. HREM and Raman results evidenced that the material is constituted, irrespective of the temperature of the final calcination step, by an ensemble of randomly oriented nanocrystals with fluorite structure. This study opens new perspectives for the design of synthetic approaches to prepare nanooxides (fluorites and pyrochlores) and the analysis of their crystalline structure

Progress on lanthanide-based organic–inorganic hybrid phosphors

Research on organic–inorganic hybrid materials containing trivalent lanthanide ions (Ln3+) is a very active field that has rapidly shifted in the last couple of years to the development of eco-friendly, versatile and multifunctional systems, stimulated by the challenging requirements of technological applications spanning domains as diverse as optics, environment, energy, and biomedicine. This tutorial review offers a general overview of the myriad of advanced Ln3+-based organic–inorganic hybrid materials recently synthesised, which may be viewed as a major innovation in areas of phosphors, lighting, integrated optics and optical telecommunications, solar cells, and biomedicin

Overexpression of wild-type human APP in mice causes cognitive déficits and pathological features unrelated to Abeta levels

Transgenic mice expressing mutant human amyloid precursor protein (APP) develop an age-dependent amyloid pathology and memory deficits, but no overt neuronal loss. Here, in mice overexpressing wild-type human APP (hAPPwt) we found an early memory impairment, particularly in the water maze and to a lesser extent in the object recognition task, but β-amyloid peptide (Aβ42) was barely detectable in the hippocampus. In these mice, hAPP processing was basically non-amyloidogenic, with high levels of APP carboxy-terminal fragments, C83 and APP intracellular domain. A tau pathology with an early increase in the levels of phosphorylated tau in the hippocampus, a likely consequence of enhanced ERK1/2 activation, was also observed. Furthermore, these mice presented a loss of synapse-associated proteins: PSD95, AMPA and NMDA receptor subunits and phosphorylated CaMKII. Importantly, signs of neurodegeneration were found in the hippocampal CA1 subfield and in the entorhinal cortex that were associated to a marked loss of MAP2 immunoreactivity. Conversely, in mice expressing mutant hAPP, high levels of Aβ42 were found in the hippocampus, but no signs of neurodegeneration were apparent. The results support the notion of Aβ- independent pathogenic pathways in Alzheimer's disease