292 research outputs found
In-situ Investigation of the Early Stage of TiO2 epitaxy on (001) SrTiO3
We report on a systematic study of the growth of epitaxial TiO2 films
deposited by pulsed laser deposition on Ti-terminated (001) SrTiO3 single
crystals. By using in-situ reflection high energy electron diffraction, low
energy electron diffraction, x-ray photoemission spectroscopy and scanning
probe microscopy, we show that the stabilization of the anatase (001) phase is
preceded by the growth of a pseudomorphic Sr-Ti-O intermediate layer, with a
thickness between 2 and 4 nm. The data demonstrate that the formation of this
phase is related to the activation of long range Sr migration from the
substrate to the film. The role of interface Gibbs energy minimization, as a
driving force for Sr diffusion, is discussed. Our results enrich the phase
diagram of the Sr-Ti-O system under epitaxial strain opening the roudeficient
SrTiO phase.Comment: 8 pages, 7 figure
Electronic phase separation near the superconductor-insulator transition of Nd1+xBa2âxCu3O7âÎŽ thin films studied by an electric-field-induced doping effect
We report a detailed study of the transport properties of Nd(1+x)Ba(2-x)Cu(3)O(7-delta) thin films with doping changed by field effect. The data cover the whole superconducting to insulating transition and show remarkable Similarities with the effect of chemical doping in high critical temperature superconductors. The results suggest that the add-on of carriers is accompanied by an electronic phase separation, independent on the details of the doping mechanism
Role of interband scattering in neutron irradiated MgB thin films by Scanning Tunneling Spectroscopy measurements
A series of MgB thin films systematically disordered by neutron
irradiation have been studied by Scanning Tunneling Spectroscopy. The c-axis
orientation of the films allowed a reliable determination of local density of
state of the band. With increasing disorder, the conductance peak moves
towards higher voltages and becomes lower and broader, indicating a monotonic
increase of the gap and of the broadening parameter. These results are
discussed in the frame of two-band superconductivity.Comment: The text will be submitted in Latex format, and the corresponding pdf
file should take 6 pages. There are 5 figures (eps files submitted) and 1
tabl
Tomato ionomic approach for food fortification and safety.
Food fortification is an issue of paramount of importance for people living both in developed
and in developing countries. Among substances listed as "nutriceuticals", essential minerals have
been recognised for their involvement in several healthy issues, involving all ages. In this frame,
food plants are playing a pivotal role since their capability to compartmentalise ions and proteinmetal
complexes in edible organs. Conversely, the accumulation of high metal levels in those
organs may lead to safety problems. In the recent years, thanks to the availability of new and
improved analytical apparatus in both ionic and genomic/transcrittomics areas, it is became feasible
to couple data coming from plant physiology and genetics. Ionomics is the discipline that studies
the cross-analysis of both data sets. Our group, in the frame of GenoPom project granted by MiUR,
is interested to study the ionomics of tomatoes cultivars derived by breeding programmes in which
wild relatives have been used to transfer several useful traits, such as resistance to biotic or abiotic
stresses, fruit composition and textiture, etc. The introgression of the wild genome into the
cultivated one produces new gene combinations. They might lead to the expression of some traits,
such as increased or reduced adsorption of some metals and their exclusion or loading into edible
organs, thus strongly involving the nutritional food value. Our final goal is to put together data
coming from ions homeostasis and gene expression analyses, thus obtaining an ionomic tomato
map related to ions absorption, translocation and accumulation in various plant organs, fruits
included. To follow our hypothesis, we are studying the ionome of Solanum lycopersicum cv. M82
along with 76 Introgression Lines (ILs) produced by interspecific crosses between this cultivar and
the wild species S. pennellii. These ILs are homozygous for small portions of the wild species
genome introgressed into the domesticated M82 one. They are used as a useful tool for mapping
QTL associated with many traits of interest. It is worthy to note that, until now, little information is
available on QTL for ions accumulation in tomato. Moreover, as our knowledge, effects of new
gene combinations in introgressed lines on ions uptake related to food safety have not been
extensively studied. In this presentation we show results coming from the ionome analysis, carried
out on S . lycopersicum M82 and several ILs. Plants were grown in pots in a greenhouse and
watered with deionised water Thirty day-old plants were left to grow for 15 days in the presence of
non-toxic concentration of Cd, Pb, As, Cr and Zn given combined. Leaves of all plants were then
harvested and stored at -80°C for ionome and gene expression analyses. Preliminary results of
ionome analysis of S. lycopersicum M82 and several ILs, carried out using an ICP-MS, showed that
traits correlated to toxic metals and micronutrients accumulation in apical leaves were significantly
modified in response to specific genetic backgrounds. Those results are perhaps due to the
introgression of traits linked to uptake, translocation and accumulation of useful and/or toxic metal
into plant apical leaves and to interactions of the wild type introgressed genomic regions with the
cultivated genome. Also, data are shown on the identification and isolation of Solanum gene
sequences related to ions uptake, translocation and accumulation, useful for further real-time gene
expression evaluation in both cultivated and ILs during the treatments with the above-mentioned
metals
Increased Expression of Autophagy-Related Genes in Alzheimerâs DiseaseâType 2 Diabetes Mellitus Comorbidity Models in Cells
The association between Alzheimerâs disease (AD) and type 2 diabetes mellitus (T2DM) has been extensively demonstrated, but despite this, the pathophysiological mechanisms underlying it are still unknown. In previous work, we discovered a central role for the autophagy pathway in the common alterations observed between AD and T2DM. In this study, we further investigate the role of genes belonging to this pathway, measuring their mRNA expression and protein levels in 3xTg-AD transgenic mice, an animal model of AD. Moreover, primary mouse cortical neurons derived from this model and the human H4Swe cell line were used as cellular models of insulin resistance in AD brains. Hippocampal mRNA expression showed significantly different levels for Atg16L1, Atg16L2, GabarapL1, GabarapL2, and Sqstm1 genes at different ages of 3xTg-AD mice. Significantly elevated expression of Atg16L1, Atg16L2, and GabarapL1 was also observed in H4Swe cell cultures, in the presence of insulin resistance. Gene expression analysis confirmed that Atg16L1 was significantly increased in cultures from transgenic mice when insulin resistance was induced. Taken together, these results emphasise the association of the autophagy pathway in AD-T2DM co-morbidity, providing new evidence about the pathophysiology of both diseases and their mutual interaction
The Role of IgLON Cell Adhesion Molecules in Neurodegenerative Diseases
In the brain, cell adhesion molecules (CAMs) are critical for neurite outgrowth, axonal fasciculation, neuronal survival and migration, and synapse formation and maintenance. Among CAMs, the IgLON family comprises five members: Opioid Binding Protein/Cell Adhesion Molecule Like (OPCML or OBCAM), Limbic System Associated Membrane Protein (LSAMP), neurotrimin (NTM), Neuronal Growth Regulator 1 (NEGR1), and IgLON5. IgLONs exhibit three N-terminal C2 immunoglobulin domains; several glycosylation sites; and a glycosylphosphatidylinositol anchoring to the membrane. Interactions as homo- or heterodimers in cis and in trans, as well as binding to other molecules, appear critical for their functions. Shedding by metalloproteases generates soluble factors interacting with cellular receptors and activating signal transduction. The aim of this review was to analyse the available data implicating a role for IgLONs in neuropsychiatric disorders. Starting from the identification of a pathological role for antibodies against IgLON5 in an autoimmune neurodegenerative disease with a poorly understood mechanism of action, accumulating evidence links IgLONs to neuropsychiatric disorders, albeit with still undefined mechanisms which will require future thorough investigations
Origin of interface magnetism in BiMnO3/SrTiO3 and LaAlO3/SrTiO3 heterostructures
Possible ferromagnetism induced in otherwise non-magnetic materials has been
motivating intense research in complex oxide heterostructures. Here we show
that a confined magnetism is realized at the interface between SrTiO3 and two
insulating polar oxides, BiMnO3 and LaAlO3. By using polarization dependent
x-ray absorption spectroscopy, we find that in both cases the magnetic order is
stabilized by a negative exchange interaction between the electrons transferred
to the interface and local magnetic moments. These local magnetic moments are
associated to Ti3+ ions at the interface itself for LaAlO3/SrTiO3 and to Mn3+
ions in the overlayer for BiMnO3/SrTiO3. In LaAlO3/SrTiO3 the induced magnetic
moments are quenched by annealing in oxygen, suggesting a decisive role of
oxygen vacancies in the stabilization of interfacial magnetism.Comment: 5 pages, 4 figure
Quantized conductance in a one-dimensional ballistic oxide nanodevice
Electric-field effect control of two-dimensional electron gases (2-DEG) has
enabled the exploration of nanoscale electron quantum transport in
semiconductors. Beyond these classical materials, transition metal-oxide-based
structures have d-electronic states favoring the emergence of novel quantum
orders absent in conventional semiconductors. In this context, the
LaAlO3/SrTiO3 interface that combines gate-tunable superconductivity and
sizeable spin-orbit coupling is emerging as a promising platform to realize
topological superconductivity. However, the fabrication of nanodevices in which
the electronic properties of this oxide interface can be controlled at the
nanoscale by field-effect remains a scientific and technological challenge.
Here, we demonstrate the quantization of conductance in a ballistic quantum
point contact (QPC), formed by electrostatic confinement of the LaAlO3/SrTiO3
2-DEG with a split-gate. Through finite source-drain voltage, we perform a
comprehensive spectroscopic investigation of the 3d energy levels inside the
QPC, which can be regarded as a spectrometer able to probe Majorana states in
an oxide 2-DEG
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