On the energy conversion efficiency in magnetic hyperthermia applications: A new perspective to analyze the departure from the linear regime

The success of magnetic hyperthermia cancer treatments rely strongly on the magnetic properties of the nanoparticles and their intricate dependence on the externally applied field. This is particularly more so as the response departs from the low field linear regime. In this paper we introduce a new parameter, referred to as the efficiency in converting electromagnetic energy into thermal energy, which is shown to be remarkably useful in the analysis of the system response, especially when the power loss is investigated as a function of the applied field amplitude. Using numerical simulations of dynamic hysteresis, through the stochastic Landau-Lifshitz model, we map in detail the efficiency as a function of all relevant parameters of the system and compare the results with simple-yet powerful-predictions based on heuristic arguments about the relaxation time. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4705392]Brazilian funding agency CNPqBrazilian funding agency CAPESBrazilian funding agency FINEPBrazilian funding agency FAPEGBrazilian funding agency FAPESPBrazilian funding agency FUNAP

Magnetic Body Force

We have studied magnetic force on sperical magnetic fluid samples with a wide range of concentrations by pendulum method. The results demonstrate good agreement with Kelvin body force and show that other force expressions clearly deviate from experimental data for large sussceptibility values. © World Scientific Publishing Company

Improving Surfactant Grafting In Magnetic Colloids

The grafting number of surfactant coating on magnetite nanoparticles in a magnetic colloid (magnetic fluid), defined as the number of surfactant molecules adsorbed per surface area of nanoparticles, was successfully obtained from the atomic absorption spectroscopy and transmission electron microscopy. We found that the increases of grafting number with the molar concentration of surfactant and the adsorption temperature can be quantitatively measured, making it possible to produce well controlled, stable magnetic colloids that are precursors for many magnetic nanostructures. © 2006 Elsevier B.V. All rights reserved

Decreasing nanofluid droplet heating time with alternating magnetic fields

Pages: 08430

Field-induced flocculation on biocompatible magnetic colloids

Field dependence of the optical transmission of a polyaspartic-coated magnetite magnetic fluid dispersed in water was investigated at different particle volume fractions. The particle size distribution of the sample was obtained from the analysis of the transmission electron microscopy pictures. The transmissivity decreased increasing the magnetic field until a critical field is achieved. Above this value, the opposite effect was observed. Indeed, the critical field decreases the higher the particle volume fraction being in qualitative similarity with phase separation behavior. However, the origin of the effect is attributed to the precipitation of field-induced nanoparticle chains. These phenomena might be useful on obtaining one-dimensional nanoparticle arrangements.Fil: Cintra, E. R.. Universidade Federal de Goiás; BrasilFil: Santos Junior, J. L.. Universidade Federal de Goiás; BrasilFil: Socolovsky, Leandro Martin. Universidade Federal de Goiás; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Buske, N.. MagneticFluids; AlemaniaFil: Bakuzis, A. F.. Universidade Federal de Goiás; Brasi

Renal perfusion evaluation by alternating current biosusceptometry of magnetic nanoparticles

a b s t r a c t Alternating current susceptometry, a simple and affordable technique, was employed to study the sensitivity of this approach to assess rat kidney perfusion by the injection of 200 μL of magnetic nanoparticles with a concentration of 23 mg/mL in the femoral vein and the measurement of the signal above the kidney. The instrument was able to detect the signal and the transit time of the first and second pass were measured in five animals with average values of 13.67 4.3 s and 20.6 7 7.1 s

Biodistribution Profile of Magnetic Nanoparticles in Cirrhosis-Associated Hepatocarcinogenesis in Rats by AC Biosusceptometry

Since magnetic nanoparticles (MNPs) have been used as multifunctional probes to diagnose and treat liver diseases in recent years, this study aimed to assess how the condition of cirrhosis-associated hepatocarcinogenesis alters the biodistribution of hepatic MNPs. Using a real-time image acquisition approach, the distribution profile of MNPs after intravenous administration was monitored using an AC biosusceptometry (ACB) assay. We assessed the biodistribution profile based on the ACB images obtained through selected regions of interest (ROIs) in the heart and liver position according to the anatomical references previously selected. The signals obtained allowed for the quantification of pharmacokinetic parameters, indicating that the uptake of hepatic MNPs is compromised during liver cirrhosis, since scar tissue reduces blood flow through the liver and slows its processing function. Since liver monocytes/macrophages remained constant during the cirrhotic stage, the increased intrahepatic vascular resistance associated with impaired hepatic sinusoidal circulation was considered the potential reason for the change in the distribution of MNPs

Renal perfusion evaluation by alternating current biosusceptometry of magnetic nanoparticles

Alternating current susceptometry, a simple and affordable technique, was employed to study the sensitivity of this approach to assess rat kidney perfusion by the injection of 200 mu L of magnetic nanoparticles with a concentration of 23 mg/mL in the femoral vein and the measurement of the signal above the kidney. The instrument was able to detect the signal and the transit time of the first and second pass were measured in five animals with average values of 13.6 +/- 4.3 s and 20.6 +/- 7.1 s. (C) 2014 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES