Synthesis, characterization, and sensitivity tests of La0.8Ba0.1Bi0.1FeO3 nanoparticles towards a few parts-per-billion of acetone gas.

In the present paper, the La0.8Ba0.1Bi0.1FeO3 powders were synthesized via the auto-combustion method. The optical, the positron annihilation spectroscopy and the gas sensing properties of our sample were investigated simultaneously. FTIR spectrum revealed the antisymmetric deformation vibrations of the Fe-O and Fe-O-Fe bonds inside the octahedron FeO6. The optical bandgap (Egap) of the La0.8Ba0.1Bi0.1FeO3 compound was found to be equal to 2.23 eV. We confirmed by the positron annihilation studies, the existence of open volume defects and vacancy sized defects, at the grain/interfaces between vacancy clusters and grains at the interfaces intersection (triple-lines). Notably, the La0.8Ba0.1Bi0.1FeO3 perovskite exhibits an excellent response toward acetone gas, with ultra-fast response and recovery times to some parts-per-billion (ppb) of this tested gas.

A method to produce a flexible and customized fuel models dataset.

Simulation of vegetation fires very often resorts to fire-behavior models that need fuel models as input. The lack of fuel models is a common problem for researchers and fire managers because its quality depends on the quality/availability of data. In this study we present a method that combines expert- and research-based knowledge with several sources of data (e.g. satellite and fieldwork) to produce customized fuel models maps. Fuel model classes are assigned to land cover types to produce a basemap, which is then updated using empirical and user-defined rules. This method produces a map of surface fuel models as detailed as possible. It is reproducible, and its flexibility relies on juxtaposing independent spatial datasets, depending on their quality or availability. This method is developed in a ModelBuilder/ArcGis toolbox named FUMOD that integrates ten sub-models. FUMOD has been used to map the Portuguese annual fuel models grids since 2019, supporting regional fire risk assessments and suppression decisions. Datasets, models and supplementary files are available in a repository (https://github.com/anasa30/PT_FuelModels). •FUMOD is a flexible toolbox with ten sub-models included that maps updated Portuguese fuel models.

Study of physical properties of the Li0.5MgFe1.5O3.5 ferrite nanoparticles.

In the present research study, the structural, optical, magnetic, electrical and dielectrical properties of the spinel ferrite Li0.5MgFe1.5O3.5, synthesized using a sol-gel auto-combustion method were studied. X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy revealed that this sample crystallizes in a cubic spinel structure with space group Fd3̄m. Moreover, the optical investigation by UV-visible spectroscopy has revealed that the band gap for our sample is (E g = 2.87 eV), which shows that our compound is a potential candidate for optoelectronic applications. The values of the remanent magnetization M r = 0.13 emu g-1, of the coercive field H C = 4.65 Oe deduced from the hysteresis loop, are very low, suggesting the superparamagnetic behavior of our sample. Additionally, the temperature coefficient of resistance (TCR) is -19% affirmed that Li0.5MgFe1.5O3.5 ferrite is a good candidate for detecting infrared radiation and infrared bolometric applications. Indeed, the activation energies were calculated from the imaginary part of the impedance, the electrical conductivity, and the imaginary part of the modulus, thus demonstrating that the charge carriers involved in the processes of conduction and relaxation are the same.

Research on the physical properties of LiMn0.5Fe2O4 spinel ferrites by the combination of optical, magnetic, and dielectric behaviors.

Ferrite compounds have recently attracted significant interest because of their multifunctional properties. This work investigates the optical, magnetic, and dielectric properties of a LiMn0.5Fe2O4 ferrite prepared by a solid-state reaction. Raman spectroscopy analysis substantiated the presence of the 5 active modes representing the vibration of the oxygen anion at both tetrahedral and octahedral sites. The direct optical band gap was estimated to be 3.51 eV, which indicates the semiconductor behavior of the compound. A theoretical modulation of the hysteresis loop was done to confirm the dominance of the ferromagnetic contribution over the antiferromagnetic one. Furthermore, the dielectric permittivity result indicated a colossal value of the order of 103. The dielectric losses are characterized by the Giuntini law to extract the relaxation process, which is hidden by the DC-conductivity process. Our results indicate the potential of LiMn0.5Fe2O4 for applications in multifunctional devices.

Wildfires in Europe: Burned soils require attention.

Annually, millions of hectares of land are affected by wildfires worldwide, disrupting ecosystems functioning by affecting on-site vegetation, soil, and above- and belowground biodiversity, but also triggering erosive off-site impacts such as water-bodies contamination or mudflows. Here, we present a soil erosion assessment following the 2017's wildfires at the European scale, including an analysis of vegetation recovery and soil erosion mitigation potential. Results indicate a sharp increase in soil losses with 19.4 million Mg additional erosion in the first post-fire year when compared to unburned conditions. Over five years, 44 million Mg additional soil losses were estimated, and 46% of the burned area presented no signs of full recovery. Post-fire mitigation could attenuate these impacts by 63-77%, reducing soil erosion to background levels by the 4th post-fire year. Our insights may help identifying target policies to reduce land degradation, as identified in the European Union Soil, Forest, and Biodiversity strategies.

Investigation of temperature and frequency dependence of the dielectric properties of multiferroic (La0.8Ca0.2)0.4Bi0.6FeO3 nanoparticles for energy storage application.

In this work we synthesized the multifunctional (La0.8Ca0.2)0.4Bi0.6FeO3 material using a sol-gel process. Structural and morphologic investigations reveal a Pnma perovskite structure at room temperature with spherical and polygonal nanoparticles. A detailed study of the temperature dependence of the dielectric and electrical properties of the studied material proves a typical FE-PE transition with a colossal value of real permittivity at 350 K that allows the use of this material in energy storage devices. Thus, the investigation of the frequency dependence of the ac conductivity proves a correlated barrier hopping (CBH) conduction mechanism to be dominant in the temperature ranges of 150-170 K; the two observed Jonscher's power law exponents, s 1 and s 2 between 180 K and 270 K correspond to the observed dispersions in the ac conductivity spectra in this temperature region, unlike in the temperature range of 250-320 K, the small polaron tunnel (NSPT) was considered the appropriate conduction model.

An international survey of imaging practices in radiotherapy.

Improvements in delivery of radiation dose to target tissues in radiotherapy have increased the need for better image quality and led to a higher frequency of imaging patients. Imaging for treatment planning extends to function and motion assessment and devices are incorporated into medical linear accelerators (linacs) so that regions of tissue can be imaged at time of treatment delivery to ensure dose distributions are delivered as accurately as possible. A survey of imaging in 97 radiotherapy centres in nine countries on six continents has been undertaken with an on-line questionnaire administered through the International Commission on Radiological Protection mentorship programme to provide a snapshot of imaging practices. Responses show that all centres use CT for planning treatments and many utilise additional information from magnetic resonance imaging and positron emission tomography scans. Most centres have kV cone beam CT attached to at least some linacs and use this for the majority of treatment fractions. The imaging options available declined with the human development index (HDI) of the country, and the frequency of imaging during treatment depended more on country than treatment site with countries having lower HDIs imaging less frequently. The country with the lowest HDI had few kV imaging facilities and relied on MV planar imaging intermittently during treatment. Imaging protocols supplied by vendors are used in most centres and under half adapt exposure conditions to individual patients. Recording of patient doses, a knowledge of which is important in optimisation of imaging protocols, was limited primarily to European countries.

Broad Diversity of Near-Infrared Single-Photon Emitters in Silicon.

We report the detection of individual emitters in silicon belonging to seven different families of optically active point defects. These fluorescent centers are created by carbon implantation of a commercial silicon-on-insulator wafer usually employed for integrated photonics. Single photon emission is demonstrated over the 1.1-1.55 µm range, spanning the O and C telecom bands. We analyze their photoluminescence spectra, dipolar emissions, and optical relaxation dynamics at 10 K. For a specific family, we show a constant emission intensity at saturation from 10 K to temperatures well above the 77 K liquid nitrogen temperature. Given the advanced control over nanofabrication and integration in silicon, these individual artificial atoms are promising systems to investigate for Si-based quantum technologies.

Mechanical Thrombectomy in Nighttime Hours: Is There a Difference in 90-Day Clinical Outcome for Patients with Ischemic Stroke?

BACKGROUND AND PURPOSE: Few data are available regarding the influence of the timing of ischemic stroke management, such as daytime and nighttime hours, on the delay of mechanical thrombectomy, the effectiveness of revascularization, and clinical outcomes. We aimed to investigate whether admission during nighttime hours could impact the clinical outcome (mRS at 90 days) of patients with acute ischemic stroke treated by mechanical thrombectomy. MATERIALS AND METHODS: We retrospectively analyzed 169 patients (112 treated during daytime hours and 57 treated during nighttime hours) with acute ischemic stroke in the anterior cerebral circulation. The main outcome was the rate of patients achieving functional independence at 90 days (mRS ≤2), depending on admission time. RESULTS: In patients admitted during nighttime hours, the rate of mRS ≤ 2 at 90 days was significantly higher (51% versus 35%, P = .05) compared with those admitted in daytime hours. Patients in daytime and nighttime hours were comparable regarding admission and treatment characteristics. However, patients in nighttime hours tended to have a higher median NIHSS score at admission (P = .08) and to be younger (P = .08), especially among the mothership group (P = .09). The multivariate logistic regression analysis confirmed that patients in nighttime hours had better functional outcomes at 90 days than those in daytime hours (P = .018; 95% CI, 0.064-0.770; OR = 0.221). CONCLUSIONS: In a highly organized stroke care network, mechanical thrombectomy is quite effective in the nighttime hours among acute ischemic stroke presentations. Unexpectedly, we found that those patients achieved favorable clinical outcomes more frequently than those treated during daytime hours. Larger series are needed to confirm these results.

Structural, morphological, Raman, dielectric and electrical properties of La1-2x Ba x Bi x FeO3 (0.00 ≤ x ≤ 0.20) compounds.

La1-2x Ba x Bi x FeO3 (0.00 ≤ x ≤ 0.20) nanoparticles were prepared by the auto-combustion method using glycine as a combustion fuel. X-ray diffractometry (XRD) measurements confirmed the orthorhombic structure of the synthesized compounds with the Pnma space group as a principal majority phase and showed the presence of a very minor secondary phase when x > 0.1. The nanosize criterion of the prepared compounds was confirmed from the crystallite size values calculated using the Williamson-Hall formalism. The relaxation process has been studied by the frequency dependence of the imaginary parts of impedance and modulus (Z'' and M'') which satisfied the Arrhenius law. Nyquist plots allowed us to obtain an adequate equivalent circuit involving the grains and grain boundary contributions. The activation energies calculated from Z'', M'' and the resistance of both contributions deduced from the Nyquist plots are found to be very similar. The conduction mechanism has been analyzed using the temperature dependence of the exponent Jonscher's power law parameter which confirms the NSPT conduction mechanism type for all compounds with an enhancement of the binding energy of the charge carrier (W H) with the substitution.

Study of the influence of 2.5% Mg2+ insertion in the B-site of La0.8Ca0.1Pb0.1FeO3 on its structural, electrical and dielectric properties.

This work involves the synthesis and study of physical properties of the La0.8Ca0.1Pb0.1Fe0.975Mg0.025O3 compound, which has been characterized by various experimental techniques, such as X-ray diffraction, SEM and complex impedance spectroscopy. The structural study showed that the La0.8Ca0.1Pb0.1Fe0.975Mg0.025O3 compound crystallized in the orthorhombic structure with the Pnma space group. The particle size and the surface morphology of this compound have been analysed using SEM. The particle size was found to be around 120 nm and we confirmed that one particle contains more than one crystallite. Importantly, the studied compound presented a giant dielectric permittivity (ε' of around 9 × 104 at high temperature and low frequencies). An equivalent electric circuit has been deduced from the Nyquist plots of the complex impedance parts (Z'' vs. Z') to correctly describe the electrical behavior of the La0.8Ca0.1Pb0.1Fe0.975Mg0.025O3 compound. The chosen circuit consists of two cells mounted in series corresponding to the grain and grain boundary contributions. The electrode contribution has been detected from the frequency dependence of the imaginary part of modulus where the activation energy of each constitution has been calculated. The relaxation process and the electrical conductivity are attributed to the same type of charge carriers characterized by similar values of the activation energy determined from loss factor tangent (tg(δ)), the imaginary part of the permittivity and the modulus spectrum.

Electrical conductivity and dielectric properties of Sr doped M-type barium hexaferrite BaFe12O19.

The hexaferrite Ba1-x Sr x Fe12O19 compounds with x = 0, 0.5 and 1 were synthesized by the autocombustion method. X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM) were used for structural and morphological studies.

Neurological improvement predicts clinical outcome after acute basilar artery stroke thrombectomy.

BACKGROUND AND PURPOSE: Mechanical thrombectomy (MT) is the standard of care for patients with anterior circulation large vessel occlusion. Early neurological improvement (ENI), defined as a reduction of ≥ 8 on the National Institutes of Health Stroke Scale (NIHSS) compared with baseline score, or an NIHSS score of 0 or 1 at 24 h after MT, is a strong predictor of 3-month favorable outcome in such patients. The impact of ENI after MT in stroke patients with basilar artery occlusion (BAO) on 3-month outcome is not clear. We aimed to study the effects of ENI in patients with BAO. METHODS: We performed a retrospective analysis of a multicenter prospective cohort of all consecutive stroke patients with BAO who underwent MT. We compared clinical outcomes between BAO patient groups according to ENI status. Multivariate analyses were performed to determine the impact of ENI on favorable 90-day outcome (modified Rankin scale score 0-3) and to report factors contributing to ENI. RESULTS: A total of 237 patients were included. ENI was observed in 70 patients (30%). Outcomes were significantly better in ENI-positive patients, with 84% achieving favorable outcome (mRS score 0-3) at 3 months versus 30% for ENI-negative patients (P < 0.0001). In multivariate analysis, ENI was an independent predictive factor associated with higher rates of favorable outcome {odds ratio (OR) 18.12 [95% confidence interval (CI) 3.95-83.10]; P = 0.0001}. Higher number of passes [OR 0.62 (95% CI 0.43-0.89); P = 0.010] and need for stenting [OR 0.27 (95% CI 0.07-0.95); P = 0.041] were negatively associated with ENI. CONCLUSION: Early neurological improvement on day 1 following MT for BAO is a strong independent predictor of a favorable 3-month clinical outcome.

Fabrication of spectrally sharp Si-based dielectric resonators: combining etaloning with Mie resonances.

We use low-resolution optical lithography joined with solid state dewetting of crystalline, ultra-thin silicon on insulator (c-UT-SOI) to form monocrystalline, atomically smooth, silicon-based Mie resonators in well-controlled large periodic arrays. The dewetted islands have a typical size in the 100 nm range, about one order of magnitude smaller than the etching resolution. Exploiting a 2 µm thick SiO2 layer separating the islands and the underlying bulk silicon wafer, we combine the resonant modes of the antennas with the etalon effect. This approach sets the resonance spectral position and improves the structural colorization and the contrast between scattering maxima and minima of individual resonant antennas. Our results demonstrate that templated dewetting enables the formation of defect-free, faceted islands that are much smaller than the nominal etching resolution and that an appropriate engineering of the substrate improves their scattering properties. These results are relevant to applications in spectral filtering, structural color and beam steering with all-dielectric photonic devices.

Effect of Bi-substitution into the A-site of multiferroic La0.8Ca0.2FeO3 on structural, electrical and dielectric properties.

(La0.8Ca0.2)1-x Bi x FeO3 (x = 0.00, 0.05, 0.10, 0.15 and 0.20) (LCBFO) multiferroic compounds have been prepared by the sol-gel method and calcined at 800 °C. X-ray diffraction results have shown that all samples crystallise in the orthorhombic structure with the Pnma space group. Electrical and dielectric characterizations of the synthesized materials have been performed using complex impedance spectroscopy techniques in the frequency range from 100 Hz to 1 MHz and in a temperature range from 170 to 300 K. The ac-conductivity spectra have been analysed using Jonscher's power law σ(ω) = σ dc + Aω s , where the power law exponent (s) increases with the temperature. The imaginary part of the complex impedance (Z'') was found to be frequency dependent and shows relaxation peaks that move towards higher frequencies with the increase of the temperature. The relaxation activation energy deduced from the Z'' vs. frequency plots was similar to the conduction activation energy obtained from the conductivity. Hence, the relaxation process and the conduction mechanism may be attributed to the same type of charge carriers. The Nyquist plots (Z'' vs. Z') at different temperatures revealed the appearance of two semi-circular arcs corresponding to grain and grain boundary contributions.

Structural study and large magnetocaloric entropy change at room temperature of La1-x □ x MnO3 compounds.

In this study, our central focus is to investigate the magnetocaloric characteristics of a La1-x □ x MnO3 (x = 0.1, 0.2 and 0.3) series prepared by a sol-gel technique published in Prog. Mater. Sci., 93, 2018, 112-232. The crystallographic study revealed that our compounds crystallize in a rhombohedral structure with R3̄c. Ferromagnetic (FM) and paramagnetic (PM) characters were detected from the variation in magnetization as a function of magnetic fields at different temperatures. The second order transition was verified from the Arrott plots (M 2 vs. (µ 0 H/M)), where the slopes have a positive value. In order to verify the second order, we traced the variation of magnetization vs. temperature at different magnetic fields for x = 0.2. This revealed a ferromagnetic (FM)-paramagnetic (PM) transition when temperature increases. Relying on the indirect method while using the Maxwell formula, we determined the variation in the entropy (-ΔS M) as a function of temperature for different magnetic fields for the three samples. We note that all the studied systems stand as good candidates for magnetic refrigeration with relative cooling power (RCP) values of around 131.4, 83.38 and 57.26 J kg-1 with magnetic fields below 2 T, respectively. Subsequently, the magnetocaloric effect was investigated by a phenomenological model for x = 0.2. The extracted data confirm that this phenomenological model is appropriate for the prediction of magnetocaloric properties. The study also demonstrated that this La0.8□0.2MnO3 system exhibits a universal behaviour.

GaAs nanowires with oxidation-proof arsenic capping for the growth of an epitaxial shell.

We propose an arsenic-capping/decapping method, allowing the growth of an epitaxial shell around the GaAs nanowire (NW) core which is exposed to an ambient atmosphere, and without the introduction of impurities. Self-catalyzed GaAs NW arrays were firstly grown on Si(111) substrates by solid-source molecular beam epitaxy. Aiming for protecting the active surface of the GaAs NW core, the arsenic-capping/decapping method has been applied. To validate the effect of this method, different core/shell NWs have been fabricated. Analyses highlight the benefit of the As capping-decapping method for further epitaxial shell growth: an epitaxial shell with a smooth surface is achieved in the case of As-capped-decapped GaAs NWs, comparable to the in situ grown GaAs/AlGaAs NWs. This As capping method opens a way for the epitaxial growth of heterogeneous material shells such as functional oxides using different reactors.

GaAs Core/SrTiO3 Shell Nanowires Grown by Molecular Beam Epitaxy.

We have studied the growth of a SrTiO3 shell on self-catalyzed GaAs nanowires grown by vapor-liquid-solid assisted molecular beam epitaxy on Si(111) substrates. To control the growth of the SrTiO3 shell, the GaAs nanowires were protected using an arsenic capping/decapping procedure in order to prevent uncontrolled oxidation and/or contamination of the nanowire facets. Reflection high energy electron diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were performed to determine the structural, chemical, and morphological properties of the heterostructured nanowires. Using adapted oxide growth conditions, it is shown that most of the perovskite structure SrTiO3 shell appears to be oriented with respect to the GaAs lattice. These results are promising for achieving one-dimensional epitaxial semiconductor core/functional oxide shell nanostructures.

[Infectious pleurisy as first sign of multiple myeloma in a young 28 years old]. / Pleurésie infectieuse révélatrice d'un myélome multiple chez un jeune de 28ans.

Multiple myeloma is a malignant proliferation of plasma cells, mainly affecting the bone marrow. It rarely occurs in young patients. The medical observation study reveals multiple myeloma discovered through a purulent pleurisy in a 28-year-old subject. This patient was admitted to the pneumology service of the Mohamed V military hospital in Rabat for a fever and dyspnea evolving into a context of poor general condition. Clinical examination found a right pleural fluid effusion syndrome. The pleural puncture reveals a germ-free exudative purulent fluid without plasma cells. The myeloma diagnosis was suspected due to the combination of an aplastic normochromic normocytic anemia at 4.5g/dL of hemoglobin, an accelerated erythrocyte sedimentation rate, hypercalcemia, renal failure and osteolytic lesions located mainly in the skull and pelvis area, oriented by electrophoresis and serum protein immunosubstraction revealing a narrow peak in monoclonal beta-2 globulin at 70.56g/L with a lambda monoclonal gammopathy with immunoglobulin G, and confirmed by the myelogram showing a 74% rate of bone marrow plasma cells. The occurrence of myeloma at a young age is rare and the purulent pleurisy without plasma cells is a rare form of presentation and represents a poor prognosis.

[Desmoid infantile mandibular fibromatosis]. / Fibromatose desmoïde infantile de la mandibule.

INTRODUCTION: A desmoid tumor, or aggressive fibromatosis, is a benign fibrous tumor with a high potential for locoregional extension. This tumor is very rarely located in the mandible. OBSERVATION: A 2-year-old boy presented with an extensive mandibular desmoid tumor. The diagnosis was proved on histological examination. Two years after surgery, there was no recurrence. DISCUSSION: Aggressive fibromatosis is rarely located in the mandible. The differential diagnosis with malignant tumors is difficult. Surgery is the first-line treatment. However, alternative therapies should be considered, especially in children, to avoid mutilating operations.