The rapid developments in nanostructured materials and nanotechnology is starting to have a profound impact in many applications of the biomedical areas, including biomolecules, tissue engineering, and detection of biomarkers, cancer diagnosis, cancer therapy, and bioimaging. Nanotechnology applications hinge frequently on the availability in well-characterized size distributions for gold nanoparticles. In this work we implemented a methodology in order to determine gold nanoparticles size by using the UV-Vis spectra and the multivariate analysis with the principal components' analysis method. The sample size of gold nanoparticles used for correlation of this methodology were previously known (5, 10, 15, 20, 30, 40, 50, 60, and 80 nm), they were supplied by Sigma Aldrich and Ted Pella Inc. All GNPs were measurement with a spectrometer Shimadzu UV-VIS 1800 Rayleigh model over the range from 400 to 700 nm. The UV-VIS spectra was compared with the implemented methodology in order to show excellent behavior and similitude in results, which one suggests this is an outstanding usefully tool to determine the gold nanoparticle diameter.
The development of a device for generating ac magnetic fields based on a resonant inverter is presented, which has been specially designed to carry out experiments of magnetic hyperthermia. By determining the electric current in the LC resonant circuit, a maximum intensity of magnetic field around of 15 mT is calculated, with a frequency around of 206 kHz. This ac magnetic field is able to heat powdered magnetic materials embedded in biological systems to be used in biomedical applications. Indeed, in order to evaluate the sensitivity of the device we also present the measurements of the specific absorption rate in phantoms performed with commercially prepared Fe(3)O(4) and distilled water at different concentrations.
Epitaxial 200nm BiFe0.95Mn0.05O3 (BFO) film was grown by pulsed laser deposition on (111) oriented SrTiO3 substrate buffered with a 50nm thick SrRuO3 electrode. The BFO thin film shows a rhombohedral structure and a large remnant polarization of Pr = 104 µC/cm 2 . By comparing I(V) characteristics with different conduction models we reveal the presence of both bulk limited Poole-Frenkel and Schottky interface mechanisms and each one dominates in a specific range of temperature. At room temperature and under 10mW laser illumination, the as grown BFO film presents short-circuit current density (Jsc) and open circuit voltage (Voc) of 2.25mA/cm 2 and -0.55V respectively. This PV effect can be switched by applying positive voltage pulses higher than the coercive field. For low temperatures a large Voc value of about -4.5V (-225kV/cm) is observed which suggests a bulk non-centrosymmetric origin of the PV response.
The effect of 1 Hz, 30 mT pulsed magnetic fields on young adult rat femoral metaphyseal bone thickness was assessed. Ten same litter, female Wistar rats were studied; five of them underwent 30 min magnetic stimulation sessions for 20 consecutive days. The anterior and posterior cortical, as well as trabecular bone transverse thicknesses were measured. The results obtained under clear field microscopy in stimulated and control histological cuts were (in microm) 398 +/- 32 versus 260 +/- 22 (P = 0.002), 380 +/- 68 versus 252 +/- 21 (P = 0.03), and 168 +/- 11 versus 112 +/- 11 (P = 0.002), respectively. The transcranial magnetic stimulation system, approved for human therapy, generates pulsed electromagnetic fields, which induce a significant thickness increase in cortical and trabecular in vivo stimulated bone tissues. This is the first time this effect in healthy animals is shown.
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