The growth of technologically relevant compounds, Mg-doped CuCrO
2
delafossite thin films, on a quartz substrate by radio-frequency sputtering is reported in this work. The deposition, performed at ...room temperature, leads to a nanocrystalline phase with extremely low roughness and high density. Delafossite characteristic diffraction peaks were obtained as a function of the thermal treatment under primary vacuum. The electrical conductivity was optimized until 1.6 S cm
−1
with an optical transmittance of 63% in the visible range by a 600 °C annealing treatment under primary vacuum applied for 4 h. The transport properties were analyzed by Seebeck and Hall measurement, integrated spectrophotometry and optical simulation. These measurements highlighted degenerated semiconductor behavior using a hopping mechanism with a high hole concentration (10
21
cm
−3
) and a low mobility (0.2 cm
2
V
−1
s
−1
). The direct optical bandgap of 3.3 eV has been measured according to Tauc's relationship. A refractive index of 2.3 at a wavelength of 1100 nm has been determined by spectroscopic ellipsometry and confirmed by two independent modellings of the optical transmittance and reflectance spectra. All these p-type TCO optoelectronic characteristics have led to the highest Haacke's figure of merit (1.5 × 10
−7
Ω
−1
) reported so far for such delafossite materials.
The growth of technologically relevant compounds, Mg-doped CuCrO
2
delafossite thin films, on a quartz substrate by radio-frequency sputtering is reported in this work.
Quantitative, spatially-resolved measurements of intermediates in flame synthesis reactors are required for the validation of precursor decomposition and oxidation mechanisms, preceding the ...nanoparticle formation. In this work we demonstrate how the laser-induced fluorescence (LIF) can be used in a self-calibrating fashion to image absolute concentrations of the strong absorber, such as atomic iron generated during the thermal decomposition of iron pentacarbonyl precursor in the preheat zone of synthesis flame. Flame symmetry facilitates deduction of the absolute concentrations. A comparison of LIF fluorescence patterns on both sides of axisymmetric flow configuration cancels out symmetric factors such as fluorescence quantum yield, fluorescence trapping and optical aberrations. This approach, utilizing one laser beam and one spectral transition provides a refinement of previous methods that have used either two spectral transitions or two collinear laser beams in counter-propagating geometry. Its spectral resolution and the detection sensitivity of que are not compromised when the spectral width of the laser exceeds that of the absorber. The measured Fe-atom concentration field is qualitatively consistent with the predictions of nucleation theory approach and suggest that flame synthesis model should be expanded beyond the formation of small incipient iron clusters to several nm-sized iron particles.
We present a comparative study of the structure and texture at the nanoscale of two well-known high-textured laminar pyrocarbons (PyCs), the rough laminar (RL) and regenerative laminar (ReL) PyCs. ...Structure is assessed with diffraction data in the reciprocal space (coherence lengths La and Lc), and in the real space, using a pair distribution function analysis, to finely describe the in-plane features. Texture is characterized from high resolution transmission electron microscopy (HRTEM) images, by analyses of the 002 fringe properties (length and tortuosity) and of new descriptors based on the spatial variations of local orientations, allowing the measurement of the average misorientation angle between crystallites. However, the structure and texture of the RL PyC are recovered when the ReL PyC is heat-treated at 1500°C. In addition, atomistic models are generated from HRTEM images and thoroughly validated against structural and textural indicators. The latter, essentially containing three-coordinated atoms arranged in hexagonal rings, show that the materials differ from the way these rings are clustered together in large hexagonal graphene domains and connected by grain boundaries (pentagon/heptagon pairs), interlayer crosslinks (screw dislocations) and hydrogen-saturated edges.
Map generalization abstracts and simplifies geographic information to derive maps at smaller scales. The automation of map generalization requires techniques to evaluate the global quality of a ...generalized map. The quality and legibility of a generalized map is related to the complexity of the map, or the amount of clutter in the map, i.e. the excessive amount of information and its disorganization. Computer vision research is highly interested in measuring clutter in images, and this paper proposes to compare some of the existing techniques from computer vision, applied to generalized maps evaluation. Four techniques from the literature are described and tested on a large set of maps, generalized at different scales: edge density, subband entropy, quad tree complexity, and segmentation clutter. The results are analyzed against several criteria related to generalized maps, the identification of cluttered areas, the preservation of the global amount of information, the handling of occlusions and overlaps, foreground vs background, and blank space reduction.
Guadeloupe is a Caribbean archipelago. The coast proximity has been associated with improved health and well-being. It provides easy access to safe public beaches and to several private water-based ...activities. Only a small proportion of the elderly are able to enjoy these places for physical activities. Many others, in particular those with chronic diseases, are faced with limited, poorly adapted or expensive choices for these activities. Although physical activity is often recommended as a self-management strategy for improving or controlling many chronic disease, these community members are thus impeded to move from a pre-action stage to an action maintenance stage for increase of physical activity in such a context. Under the leadership of the regional swimming league, a multidisciplinary team of professionals and patient representatives was recruited to design a project to increase patients? opportunities for physical activity. Copyright Elsevier B.V.
Congenital erythropoietic porphyria (CEP) is a recessive autosomal disorder characterized by a deficiency in uroporphyrinogen III synthase (UROS), the fourth enzyme of the heme biosynthetic pathway. ...The severity of the disease, the lack of specific treatment except for allogeneic bone marrow transplantation, and the knowledge of the molecular lesions are strong arguments for gene therapy. An animal model of CEP has been designed to evaluate the feasibility of retroviral gene transfer in hematopoietic stem cells. We have previously demonstrated that the knockout of the
Uros gene is lethal in mice (
Uros
del model). This work describes the achievement of a knock-in model, which reproduces a mutation of the
UROS gene responsible for a severe UROS deficiency in humans (P248Q missense mutant). Homozygous mice display erythrodontia, moderate photosensitivity, hepatosplenomegaly, and hemolytic anemia. Uroporphyrin (99% type I isomer) accumulates in urine. Total porphyrins are increased in erythrocytes and feces, while Uros enzymatic activity is below 1% of the normal level in the different tissues analyzed. These pathological findings closely mimic the CEP disease in humans and demonstrate that the
Uros
mut248 mouse represents a suitable model of the human disease for pathophysiological, pharmaceutical, and therapeutic purposes.
Didanosine is a polar drug with poor membrane absorption and high hepatic first pass metabolism. This study aimed at developing a lipidic formulation of a glycerolipidic prodrug of didanosine in ...order to improve its bioavailability. In the course of a preformulation study, the glycerolipidic prodrug of didanosine was characterized by microscopy, DSC and XRDT. In anhydrous conditions, the prodrug displayed a polymorphic behaviour similar to that of triglycerides. Then, we evaluated three types of lipidic formulations (emulsions, mixed micelles and liposomes) in order to encapsulate the prodrug. Solubilities in water – even in the presence of taurocholate micelles – but also in some oils were very low (max 244
μg/mL) as the prodrug was found to be amphiphilic (log
P
=
2). On the contrary, the prodrug was found to be perfectly incorporated in dipalmitoylphosphatidylcholine (DPPC) multilamellar liposomes up to a ratio of 1:5 (mol:mol) prodrug:DPPC as suggested by HPLC-UV and DSC experiments. Moreover, these liposomes could be freeze-dried whereas the chemical integrity of the prodrug was preserved. Then, the freeze-dried liposomal preparation could be formulated as gastro-resistant capsules to prevent didanosine from acidic degradation. Further experiments are on the way to evaluate
in vitro the absorption of prodrug incorporated in liposomes by enterocytes.
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