Search results for "defect"
showing 10 items of 879 documents
The effect of high-In content capping layers on low-density bimodal-sized InAs quantum dots
2013
[EN] The structural and morphological features of bimodal-sized InAs/(In) GaAs quantum dots with density in the low 10(9) cm(-2) range were analyzed with transmission electron microscopy and atomic force microscopy and were related to their optical properties, investigated with photoluminescence and time-resolved photoluminescence. We show that only the family of small quantum dots (QDs) is able to emit narrow photoluminescence peaks characteristic of single-QD spectra; while the behavior of large QDs is attributed to large strain fields that may induce defects affecting their optical properties, decreasing the optical intensity and broadening the homogeneous linewidth. Then, by using a rat…
In situobservation of the generation and annealing kinetics of E ′ centres induced in amorphous SiO2by 4.7 eV laser irradiation
2011
The kinetics of E' centers induced in silica by 4.7eV laser irradiation was investigated observing in situ their optical absorption band at 5.8 eV. After exposure the defects decay due to reaction with diffusing molecular hydrogen of radiolytic origin. Hydrogen-related annealing is active also during exposure and competes with the photo-induced generation of the centers until a saturation is reached. The concentrations of E' and H2 at saturation are proportional, so indicating that the UV-induced generation processes of the two species are correlated. These results are consistent with a model in which E' and hydrogen are generated from a common precursor Si-H.
An assesment of body posture of children aged 3-6 years
2019
Background: A posture defect may be defined as a syndrome of abnormalities occurring in a relaxed upright position of the body. Deviations from the typical body shape are specific for given age and gender. Life determinants and social situation have a very significant impact on the development of body posture in young people. Aim of the study: The aim of the study was to analyse the occurrence of spinal defects in children aged 3–6 years. Material and methods: The study included 75 children aged 3–6 years. The children were examined for spinal defects using the MORA computer system. Results: Boys in the study showed a correlation between height and the inclination of the upper thoracic segm…
Temperature and concentration effects on supramolecular aggregation and phase behavior for poly(propylene oxide)–b-poly(ethylene oxide) –b-poly(propy…
2011
The micro- and mesoscopic structure of reverse Pluronic 25R4 in aqueous mixtures has been studied by SANS, SAXS and shear rheology. These techniques have been able to give a deep insight into the complex structure of the system phase diagram, that includes an isotropic water-rich liquid phase L(1), and liquid crystalline phases with hexagonal, E, or lamellar order, D. Particular attention has been paid to the isotropic water-rich phase L(1), which has a large stability region in the temperature-composition phase diagram. This region is crossed by a large "cloudy zone". Below it, namely at low temperature and composition, SANS data show the presence of polymer unimers in a gaussian coil conf…
Hybrid functional study of structural, electronic and magnetic properties of S-doped ZnO with and without neutral vacancy
2013
Abstract The structural and electronic properties of S-doped ZnO are investigated by density functional theory (DFT) and empirical pseudopotential method (EPM). Using the Heyd–Scuseria–Ernzerhof (HSE) hybrid functional with an adjusted mixing coefficient α , we obtain a good agreement on lattice parameters and band gap energy with the available experimental data. We have also investigate the Zn-vacancy effects on the electronic and magnetic properties of S-doped ZnO. Our calculations demonstrate that S impurity prefers to be close to the cation vacancy in the apical position. The magnetic analysis with the HSE functional shows a triplet state character with a total magnetic moment of 1.81 μ…
Topological–chiral magnetic interactions driven by emergent orbital magnetism
2019
Two hundred years ago, Ampère discovered that electric loops in which currents of electrons are generated by a penetrating magnetic field can mutually interact. Here we show that Ampère’s observation can be transferred to the quantum realm of interactions between triangular plaquettes of spins on a lattice, where the electrical currents at the atomic scale are associated with the orbital motion of electrons in response to the non-coplanarity of neighbouring spins playing the role of a magnetic field. The resulting topological orbital moment underlies the relation of the orbital dynamics with the topology of the spin structure. We demonstrate that the interactions of the topological orbital …
Microwave-free vector magnetometry with nitrogen-vacancy centers along a single axis in diamond
2019
Sensing vector magnetic fields is critical to many applications in fundamental physics, bioimaging, and material science. Magnetic-field sensors exploiting nitrogen-vacancy (NV) centers are particularly compelling as they offer high sensitivity and spatial resolution even at nanoscale. Achieving vector magnetometry has, however, often required applying microwaves sequentially or simultaneously, limiting the sensors' applications under cryogenic temperature. Here we propose and demonstrate a microwave-free vector magnetometer that simultaneously measures all Cartesian components of a magnetic field using NV ensembles in diamond. In particular, the present magnetometer leverages the level ant…
WNT Signaling Perturbations Underlie the Genetic Heterogeneity of Robinow Syndrome
2018
International audience; Locus heterogeneity characterizes a variety of skeletal dysplasias often due to interacting or overlapping signaling pathways. Robinow syndrome is a skeletal disorder historically refractory to molecular diagnosis, potentially stemming from substantial genetic heterogeneity. All current known pathogenic variants reside in genes within the noncanonical Wnt signaling pathway including ROR2, WNT5A, and more recently, DVL1 and DVL3. However, ∼70% of autosomal-dominant Robinow syndrome cases remain molecularly unsolved. To investigate this missing heritability, we recruited 21 families with at least one family member clinically diagnosed with Robinow or Robinow-like pheno…
Diagnostic strategy in segmentation defect of the vertebrae: a retrospective study of 73 patients
2018
BackgroundSegmentation defects of the vertebrae (SDV) are non-specific features found in various syndromes. The molecular bases of SDV are not fully elucidated due to the wide range of phenotypes and classification issues. The genes involved are in the Notch signalling pathway, which is a key system in somitogenesis. Here we report on mutations identified in a diagnosis cohort of SDV. We focused on spondylocostal dysostosis (SCD) and the phenotype of these patients in order to establish a diagnostic strategy when confronted with SDV.Patients and methodsWe used DNA samples from a cohort of 73 patients and performed targeted sequencing of the five known SCD-causing genes (DLL3,MESP2,LFNG,HES7…
Recognizable neonatal clinical features of aplasia cutis congenita
2020
Abstract Background Aplasia cutis congenita (ACC), classified in nine groups, is likely to be underreported, since milder isolated lesions in wellbeing newborns could often be undetected, and solitary lesions in the context of polymalformative syndromes could not always be reported. Regardless of form and cause, therapeutic options have in common the aim to restore the deficient mechanical and immunological cutaneous protection and to limit the risk of fluid leakage or rupture of the exposed organs. We aimed to review our institutional prevalence, comorbidities, treatment and outcome of newborns with ACC. Methods We conducted a retrospective study including all newborns affected by ACC and …