Exchange-coupling in thermal annealed bimagnetic core/shell nanoparticles

In this study we demonstrate that the effective coupling of the magnetic phases in core/shell nanoparticles can be promoted by an appropriate thermal annealing. In this way, the magnetization thermal stability of the hard ferrimagnetic CoFe2O4 oxide can be increased up to room temperature when coupled to a CoO antiferromagnetic core in an inverse core/shell structure. In addition, the results show that, being encapsulated in a ∼2 nm thick CoFe2O4 shell, the CoO core is successfully protected against oxidation which is crucial for the effectiveness of the magnetic coupling at the interface.Fil: Lavorato, Gabriel Carlos. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lima, Enio Junior. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Troiani, Horacio Esteban. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zysler, Roberto Daniel. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Winkler, Elin Lilian. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Bifunctional CoFe2O4/ZnO Core/Shell Nanoparticles for Magnetic Fluid Hyperthermia with Controlled Optical Response

Conjugation of optical and magnetic responses in a unique system at the nanoscale emerges as a powerful tool for several applications. Here, we fabricated bifunctional CoFe2O4-core/ZnO-shell nanoparticles with simultaneous photoluminescence in the visible range and ac magnetic losses suitable for hyperthermia. The structural characterization confirms that the system is formed by a ≈7 nm CoFe2O4 core encapsulated in a ≈1.5-nm-thick semiconducting ZnO shell. As expected from its high anisotropy, the magnetic losses in an ac magnetic field are dominated by the Brown relaxation mechanism. The ac magnetic response of the core/shell system can be accurately predicted by the linear response theory and differs from that one of bare CoFe2O4 nanoparticles as a consequence of changes in the viscous relaxation process due to the effect of the magnetostatic interactions. Concerning the optical properties, by comparing core/shell CoFe2O4/ZnO and single-phase ZnO nanoparticles, we found that the former exhibits a broader optical absorption and photoluminescence, both shifted to the visible range, indicating that the optical properties are closely associated with the shell-morphology of ZnO. Being focused on bifunctional nanoparticles with an optical response in the visible range and a tunable hyperthermia output, our results can help to address current open questions on magnetic fluid hyperthermia.Fil: Lavorato, Gabriel Carlos. Centro Brasileiro de Pesquisas Físicas; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Lima, Enio Junior. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Vasquez Mansilla, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Troiani, Horacio Esteban. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Zysler, Roberto Daniel. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Winkler, Elin Lilian. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentin

Development and validation of a new analytical method based on UV-visible spectroscopy for quantification of ceftaroline fosamil in powder for injection

Quantification of drugs is an essential part for ensuring quality, safety and efficacy of pharmaceutical formulations. For this, validated methods must be used in order to guarantee analytical reliability during monitoring in clinical studies and quality control. In the present study, we aim to develop a reliable, accurate, accessible and rapid UV-VIS spectrophotometry method for quantification of ceftaroline fosamil in powder for intravenous administration. Each analyzed solution was prepared individually and the only reagent used was Milli-Q water, as a solvent, making the method eco-friendly. The absorbances were measured at 242 nm, the peak absorbance found for the drug. The developed method was validated according to ICH and ANVISA guidelines, proving to be specific and demonstrating good linearity in the concentration range of 5 μg.mL-1 to 15 μg.mL-1, with determination (r2) and correlation coefficients (r) equal to 0.9999. The limits of detection and quantification found were acceptable (0.51 μg.mL-1 and 1.55 μg.mL-1, respectively).  The method exhibited excellent intermediate precision and repeatability, with relative standard deviation values of 0.87% and 0.98%, respectively. Furthermore, the method’s accuracy was confirmed, showing a mean recovery of 100 ± 2.67%. Additionally, the robustness was assayed and confirmed using Plackett-Burmann design. In conclusion, the method can easily be applied for routine quality control analysis

Gene expression parallels synaptic excitability and plasticity changes in Alzheimer's disease

Altres ajuts: CIBERNED CB06/05/0042 i BrightFocus Foundation (A2014417S)Alzheimer's disease (AD) is a neurodegenerative disorder characterized by abnormal accumulation of β-amyloid and tau and synapse dysfunction in memory-related neural circuits. Pathological and functional changes in the medial temporal lobe, a region essential for explicit memory encoding, contribute to cognitive decline in AD. Surprisingly, functional imaging studies show increased activity of the hippocampus and associated cortical regions during memory tasks in presymptomatic and early AD stages, whereas brain activity declines as the disease progresses. These findings suggest an emerging scenario where early pathogenic events might increase neuronal excitability leading to enhanced brain activity before clinical manifestations of the disease, a stage that is followed by decreased brain activity as neurodegeneration progresses. The mechanisms linking pathology with synaptic excitability and plasticity changes leading to memory loss in AD remain largely unclear. Recent studies suggest that increased brain activity parallels enhanced expression of genes involved in synaptic transmission and plasticity in preclinical stages, whereas expression of synaptic and activity-dependent genes are reduced by the onset of pathological and cognitive symptoms. Here, we review recent evidences indicating a relationship between transcriptional deregulation of synaptic genes and neuronal activity and memory loss in AD and mouse models. These findings provide the basis for potential clinical applications of memory-related transcriptional programs and their regulatory mechanisms as novel biomarkers and therapeutic targets to restore brain function in AD and other cognitive disorders

Hepatitis C virus molecular evolution: Transmission, disease progression and antiviral therapy

Hepatitis C virus (HCV) infection represents an important public health problem worldwide. Reduction of HCV morbidity and mortality is a current challenge owned to several viral and host factors. Virus molecular evolution plays an important role in HCV transmission, disease progression and therapy outcome. The high degree of genetic heterogeneity characteristic of HCV is a key element for the rapid adaptation of the intrahost viral population to different selection pressures (e.g., host immune responses and antiviral therapy). HCV molecular evolution is shaped by different mechanisms including a high mutation rate, genetic bottlenecks, genetic drift, recombination, temporal variations and compartmentalization. These evolutionary processes constantly rearrange the composition of the HCV intrahost population in a staging manner. Remarkable advances in the understanding of the molecular mechanism controlling HCV replication have facilitated the development of a plethora of direct-acting antiviral agents against HCV. As a result, superior sustained viral responses have been attained. The rapidly evolving field of anti-HCV therapy is expected to broad its landscape even further with newer, more potent antivirals, bringing us one step closer to the interferon-free era.Fil: Preciado, María Victoria. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Valva, Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños ; ArgentinaFil: Escobar Gutierrez, Alejandro. Instituto de Diagnóstico y Referencia Epidemiológicos; MéxicoFil: Rahal, Paula. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Ruiz Tovar, Karina. Instituto de Diagnóstico y Referencia Epidemiológicos; MéxicoFil: Yamasaki, Lilian. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Vazquez Chacon, Carlos. Instituto de Diagnóstico y Referencia Epidemiológicos; MéxicoFil: Martinez Guarneros, Armando. Instituto de Diagnóstico y Referencia Epidemiológicos; MéxicoFil: Carpio Pedroza, Juan Carlos. Instituto de Diagnóstico y Referencia Epidemiológicos; MéxicoFil: Fonseca Coronado, Salvador. Universidad Nacional Autónoma de México; MéxicoFil: Cruz Rivera, Mayra. Universidad Nacional Autónoma de México; Méxic

Thickness dependence of exchange coupling in epitaxial Fe 3 O 4/ CoFe 2 O 4 soft/hard magnetic bilayers

Epitaxial magnetic heterostructures of (soft-)Fe3O4/(hard-)CoFe2O4(001) have been fabricated with a varying thicknesses of soft ferrite from 5 to 25 nm. We report a change in the regime of magnetic interaction between the layers from rigid-coupling to exchange-spring behavior, above a critical thickness of the soft magnetic Fe3O4 layer. We show that the symmetry and epitaxial matching between the spinel structures of CoFe2O4 and Fe3O4 at the interface stabilize the Verwey transition close to the bulk value even for 5-nm-thick Fe3O4. The large interface exchange-coupling constant estimated from low-temperature M(H) data confirmed the good quality of the ferrite-ferrite interface and the major role played by the interface in the magnetization dynamics. The results presented here constitute a model system for understanding the magnetic behavior of interfaces in core/shell nanoparticles and magnetic oxide-based spintronic devices.Fil: Lavorato, Gabriel Carlos. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Resonancias Magnéticas; ArgentinaFil: Winkler, Elin Lilian. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Resonancias Magnéticas; ArgentinaFil: Rivas Murias, B.. Universidad de Santiago de Compostela. Facultad de Química; EspañaFil: Rivadulla, F.. Universidad de Santiago de Compostela. Facultad de Química; Españ

El mobile learning mediado con metodología PACIE para saberes constructivistas

El presente artículo titula el mobile learning mediado con metodología PACIE (presencia, alcance, capacitación, interacción, e-learning) para saberes constructivistas. El objetivo es analizar cómo los dispositivos móviles aportan en forma significativa en los procesos de aprendizaje, benefician a estudiantes y docentes a interactuar de manera inmediata en la construcción del conocimiento. En el escenario planteado se considera reflexiones de varios investigadores modernos que respaldan el m-learning, puntos de vista que permiten el análisis de concepciones para relacionar los procesos de la metodología PACIE. Este análisis permitirá considerar el uso de los dispositivos móviles para el e-learning. Lo que se quiere es mirar la brecha entre la enseñanza tradicional y los dispositivos móviles, este último despierta el interés en la mediación de aprendizajes entre docentes y estudiantes. Además, estimula el sentido de responsabilidad autónoma, y apoya y fortalece prácticas de enseñanza-aprendizaje curricular y extracurricular desde varios escenarios innovadores. En los resultados se evidencia cómo el aprendizaje se ve fortalecido cuando interactúa con el uso de los dispositivos móviles, pues permite estar conectado en cualquier lugar y en todo momento. El principal aporte de artículo es la presentación de algunas alternativas de innovación para mejorar el proceso enseñanza-aprendizaje con base en la metodología PACIE. Además, reflexionará sobre la visión del docente con respecto al uso de la tecnología.// This article entitled Mobile-learning mediated with PACIE methodology (Presence, Reach, Training, Interaction, E-learning) for constructivist knowledge. The objective is to analyze how mobile devices contribute significantly to learning processes, benefit students and teachers to interact immediately in the construction of knowledge. In the proposed scenario, reflections of several modern researchers that support m-learning are considered, points of view that allow the analysis of conceptions to relate the processes of the PACIE methodology. This analysis will allow considering the use of mobile devices for e-learning. Indeed, it is looking at the gap between traditional education and mobile devices, the latter arouses interest in the mediation of learning between teachers and students. It also stimulates the sense of autonomous responsibility, supports and strengthens curricular and extracurricular teaching-learning practices from several innovative scenarios. The results show how learning is strengthened when interacting with the use of mobile devices, as it allows you to be connected anywhere and at all times. The main contribution of an article is the presentation of some innovation alternatives to improve the teaching-learning process based on the PACIE methodology. In addition, it will reflect on the teacher’s vision regarding the use of technology

Development and validation of a new analytical method based on UV-visible spectroscopy for quantification of ceftaroline fosamil in powder for injection

Quantification of drugs is an essential part for ensuring quality, safety and efficacy of pharmaceutical formulations. For this, validated methods must be used in order to guarantee analytical reliability during monitoring in clinical studies and quality control. In the present study, we aim to develop a reliable, accurate, accessible and rapid UV-VIS spectrophotometry method for quantification of ceftaroline fosamil in powder for intravenous administration. Each analyzed solution was prepared individually and the only reagent used was Milli-Q water, as a solvent, making the method eco-friendly. The absorbances were measured at 242 nm, the peak absorbance found for the drug. The developed method was validated according to ICH and ANVISA guidelines, proving to be specific and demonstrating good linearity in the concentration range of 5 μg.mL-1 to 15 μg.mL-1, with determination (r2) and correlation coefficients (r) equal to 0.9999. The limits of detection and quantification found were acceptable (0.51 μg.mL-1 and 1.55 μg.mL-1, respectively). The method exhibited excellent intermediate precision and repeatability, with relative standard deviation values of 0.87% and 0.98%, respectively. Furthermore, the method’s accuracy was confirmed, showing a mean recovery of 100 ± 2.67%. Additionally, the robustness was assayed and confirmed using Plackett-Burmann design. In conclusion, the method can easily be applied for routine quality control analysis