Chemical synthesis and magnetic properties of monodisperse cobalt ferrite nanoparticles

In this work, a successful synthesis of magnetic cobalt ferrite (CoFe2O4) nanoparticles is presented. The synthesized CoFe2O4 nanoparticles have a spherical shape and highly monodisperse in the selected solvent. The effect of different reaction conditions such as temperature, reaction time and varying capping agents on the phase and morphology is studied. Scanning transmission electron microscopy showed that the size of these nanoparticles can be controlled by varying reaction conditions. Both X-ray diffraction and energy dispersive X-ray spectroscopy corroborate the formation of CoFe2O4 spinel structure with cubic symmetry. Due to optimized reaction parameters, each nanoparticle was shown to be a single magnetic domain with diameter ranges from 6 to 16 nm. Finally, the magnetic investigations showed that the obtained nanoparticles are superparamagnetic with a small coercivity value of about 315 Oe and a saturation magnetization of 58 emu/g at room temperature. These results make the cobalt ferrite nanoparticles promising for advanced magnetic nanodevices and biomagnetic applications.Comment: 10 pages, 9 figure

Magnetic properties in amorphous Co95­xDyxZr5 thin films

Amorphous Co95-xDyxZr5 thin films were prepared by RF sputtering and their magnetic properties were studied as a function of temperature and for the composition range 0<x<30. The mean field theory has been used to explain the temperature dependence of the magnetization. The exchange interactions between Co-Co and Dy-Co atom pairs have been evaluated. The magnetic phase diagrams are presented.Amorphous Co95-xDyxZr5 thin films were prepared by RF sputtering and their magnetic properties were studied as a function of temperature and for the composition range 0<x<30. The mean field theory has been used to explain the temperature dependence of the magnetization. The exchange interactions between Co-Co and Dy-Co atom pairs have been evaluated. The magnetic phase diagrams are presented

Magnetic studies of amorphous Fe-Dy-B ribbons

We have studied the magnetization of melt spun amorphous Fe80−xDyxB20 alloys with 0 ≤ x ≤ 7.5 under magnetic fields up to 6T, and have analyzed the results at 4.2 K on the basis of the random magnetic anisotropy model. Exchange constant and local random anisotropy KL were evaluated. Using the Sarkis´s model, the local anisotropies per atom are found to be 1.75 107 and 4 107 erg/cm3 for Fe and Dy, respectively.We have studied the magnetization of melt spun amorphous Fe80−xDyxB20 alloys with 0 ≤ x ≤ 7.5 under magnetic fields up to 6T, and have analyzed the results at 4.2 K on the basis of the random magnetic anisotropy model. Exchange constant and local random anisotropy KL were evaluated. Using the Sarkis´s model, the local anisotropies per atom are found to be 1.75 107 and 4 107 erg/cm3 for Fe and Dy, respectively

Pneumonia Recovery; Discrepancies in Perspectives of the Radiologist, Physician and Patient

BACKGROUND: Chest radiographs are often used to diagnose community-acquired pneumonia (CAP), to monitor response to treatment and to ensure complete resolution of pneumonia. However, radiological exams may not reflect the actual clinical condition of the patient. OBJECTIVE: To compare the radiographic resolution of mild to moderately severe CAP to resolution of clinical symptoms as assessed by the physician or rated by the patient. DESIGN: Prospective cohort study. PARTICIPANTS: One hundred nineteen patients admitted because of mild to moderately severe CAP with new pulmonary opacities. MAIN MEASURES: Radiographic resolution and clinical cure of CAP were determined at day 10 and 28. Radiographic resolution was defined as the absence of infection-related abnormalities; clinical cure was rated by the physician and defined by improvement of signs and symptoms. In addition, the CAP score, a patient-based symptom score, was calculated. KEY RESULTS: Radiographic resolution, clinical cure and normalization of the CAP score were observed in 30.8%, 93% and 32% of patients at day 10, and in 68.4%, 88.9% and 41.7% at day 28, respectively. More severe CAP (PSI score >90) was independently associated with delayed radiographic resolution at day 28 (OR 4.7, 95% CI 1.3-16.9). All 12 patients with deterioration of radiographic findings during follow-up had clinical evidence of treatment failure. CONCLUSIONS: In mild to moderately severe CAP, resolution of radiographic abnormalities and resolution of symptoms scored by the patient lag behind clinical cure assessed by physicians. Monitoring a favorable disease process by routine follow-up chest radiographs seems to have no additional value above following a patient's clinical cours

Application d’une structure métamatériau sous forme triangulaire pour la réalisation de Filtres Coupe Bande

Dans ce papier, nous présentons deux filtres coupe bande obtenus grâce à l’application des split triangle resonators (STRs). C’est une nouvelle particule que nous avons proposée et qui présente un ε et μ simultanément négatifs dans la même bande de fréquence. Ainsi, nous appliquons le résonateur sur deux composants microonde afin d’évaluer son impact sur leurs performances. Le premier filtre est basé sur la technologie microruban avec des STRs imprimés sur la masse. Le second filtre est dans la même catégorie et à l’inverse du premier, les STRs sont imprimés sur la ligne conductrice. Le substrat utilisé est le FR4. Nous avons procédé à une étude par simulation et avons aussi réalisé et fait une étude expérimentale des deux filtres. Les résultats expérimentaux et par simulation donnent des résultats avec une bonne similitude

Towards a multi-platform assimilative system for North Sea biogeochemistry

Oceanography has entered an era of new observing platforms, such as biogeochemical-Argo floats and gliders, some of which will provide three-dimensional maps of essential ecosystem variables on the North-West European (NWE) Shelf. In a foreseeable future operational centers will use multi-platform assimilation to integrate those valuable data into ecosystem reanalysis and forecast systems. Here we address some important questions related to glider biogeochemical data assimilation (DA) and introduce multi-platform DA in a preoperational model of the NWE Shelf sea ecosystem. We test the impact of the different multi-platform system components (glider vs. satellite, physical vs. biogeochemical) on the simulated biogeochemical variables. To characterize the model performance, we focus on the period around the phytoplankton spring bloom, since the bloom is a major ecosystem driver on the NWE Shelf. We found that the timing and magnitude of the phytoplankton bloom is insensitive to the physical DA, which is explained in the study. To correct the simulated phytoplankton bloom one needs to assimilate chlorophyll observations from glider or satellite Ocean Color (OC) into the model. Although outperformed by the glider chlorophyll assimilation, we show that OC assimilation has mostly desirable impact on the sub-surface chlorophyll. Since the OC assimilation updates chlorophyll only in the mixed layer, the impact on the sub-surface chlorophyll is the result of the model dynamical response to the assimilation. We demonstrate that the multi-platform assimilation combines the advantages of its components and always performs comparably to its best performing component