Magnetic properties of nanoscale crystalline maghemite obtained by a new synthetic route

AbstractIn this work we describe the synthesis and characterization of maghemite nanoparticles obtained by a new synthetic route. The material was synthesized using triethylamine as a coprecipitation agent in the presence of the organic ligand N,N′-bis(3,5-di-tert-butyl-catechol)-2,4-diaminotoluene (LCH3). Mössbauer spectrum at 4K shows typical hyperfine parameters of maghemite and Transmission Electron Microscopy images reveal that the nanoparticles have a mean diameter of 3.9nm and a narrow size distribution. AC magnetic susceptibility in zero field presents an Arrhenius behavior with unreasonable relaxation parameters due to the strong influence of dipolar interaction. In contrast when the measurements are performed in a 1kOe field, the effect of dipolar interactions becomes negligible and the obtained parameters are in good agreement with the static magnetic properties. The dynamic energy barrier obtained from the AC susceptibility results is larger than the expected from the average size observed by HRTEM results, evidencing the strong influence of the surface contribution to the anisotropy

Agronomic practices change the patterns of soil glomalin in olive rainfed orchards

Glomalin, a thermostable hydrophobic glycoprotein produced by arbuscular mycorrhizal fungi, plays an important role in the stability of soil aggregates and in the sequestration of C, N and heavy metals, being their concentrations dependent from agronomic practices such as tillage and application of pesticides and fertilizers. Despite the recognized importance of glomalin in soil quality, studies on olive groves are scarce. The study conducted on summer 2017 in three different rain fed orchards (cv. Cobran~osa) of Northeast Portugal revealed that both total glomalin, measured as Bradford-reactive soil protein (T-BRSP}, and the easily extractable Bradford-reactive soil protein (EE-BRSP) concentrations were lower under mechanical cultivation than on a permanent sward grazed with a flock of sheep or than on an annual legume cover crop. Moreover, higher TBRSP and EE-BRSP levels were found on orchards without phosphorus and boron supply, and also on the top soil layer (0.1 0 cm) and on tree row, mainly in younger orchards. Interestingly, one soil presented a twofold superior EE-BRSP: T- BRSP ratio than the other two soils, representing an increase of labile g lomalin, probably re lated with greater applications of copper formulations to control olive fungal diseases. This study demonstrated that less disruptive agronomic practices influences positivety the levels of glomalin, an appropriate indicator of healthy soil conditions, which in turn may favour carbon sequestration.This work was funded by the INTERACT project - •Integrative Research in Environment, Agro-Chains and Technology': no. NORTE-01-0145-FEDER- 000017, in its lines of research entitled I SAC, eo-financed by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020).info:eu-repo/semantics/publishedVersio

Monocytic/Macrophagic Pneumonitis after Intrabronchial Deposition of Vascular Endothelial Growth Factor in Neonatal Lambs

Preterm and young neonates are prone to inadequate surfactant production and are susceptible to respiratory distress syndrome characterized by alveolar damage and hyaline-membrane formation. Glucocorticoid therapy is commonly used in preterm and young infants to enhance lung maturation and surfactant synthesis. Recently, vascular endothelial growth factor (VEGF) was suggested to be a novel therapeutic agent for lung maturation that lacked adverse effects in mice. The purpose of this study was to assess the safety of incremental concentration (0.0005, 0.005, and 0.05 mg/ml) and duration (16, 24, and 32 hours) of recombinant human VEGF after bronchoscopic instillation (10 ml) in neonatal lambs. High-dose VEGF caused locally extensive plum-red consolidation that was microscopically characterized by interstitial and alveolar infiltrates of cells that were morphologically and phenotypically (CD68+) consistent with monocytes/macrophages. T cells (CD3+) and B cells (CD79+) were located primarily in bronchus/bronchiole-associated lymphoid tissue and were not consistently altered by treatment with VEGF. The dose of VEGF had significant effects on both gross lesions (P \u3c .0047) and microscopic monocyte/macrophage recruitment scores (P \u3c .0001). Thus, the VEGF dose instilled into the lung greatly influenced cellular recruitment and lesion development. The post-dosing interval of VEGF in this study had minor impact (no statistical significance) on cellular recruitment. This study showed that airway deposition of VEGF in the neonatal lamb induces monocyte/macrophage recruitment to the lung and high doses can cause severe lesions. The cellular recruitment suggests further research is needed to define dosages that are efficacious in enhancing lung maturation while minimizing potential adverse effects

Dielectric and conductivity relaxation in mixtures of glycerol with LiCl

We report a thorough dielectric characterization of the alpha relaxation of glass forming glycerol with varying additions of LiCl. Nine salt concentrations from 0.1 - 20 mol% are investigated in a frequency range of 20 Hz - 3 GHz and analyzed in the dielectric loss and modulus representation. Information on the dc conductivity, the dielectric relaxation time (from the loss) and the conductivity relaxation time (from the modulus) is provided. Overall, with increasing ion concentration, a transition from reorientationally to translationally dominated behavior is observed and the translational ion dynamics and the dipolar reorientational dynamics become successively coupled. This gives rise to the prospect that by adding ions to dipolar glass formers, dielectric spectroscopy may directly couple to the translational degrees of freedom determining the glass transition, even in frequency regimes where usually strong decoupling is observed.Comment: 8 pages, 7 figure