Magnetic Nanoparticles Hyperthermia in A Non-Adiabatic and Radiating Process

We investigate the magnetic nanoparticles hyperthermia in a non-adiabatic and radiating process through the calorimetric method. Specifically, we propose a theoretical approach to magnetic hyperthermia from a thermodynamic point of view. To test the robustness of the approach, we perform hyperthermia experiments and analyse the thermal behavior of magnetite and magnesium ferrite magnetic nanoparticles dispersed in water submitted to an alternating magnetic field. From our findings, besides estimating the specific loss power value from a non-adiabatic and radiating process, thus enhancing the accuracy in the determination of this quantity, we provide physical meaning to a parameter found in literature that still remained not fully understood, the effective thermal conductance, and bring to light how it can be obtained from experiment. In addition, we show our approach brings a correction to the estimated experimental results for specific loss power and effective thermal conductance, thus demonstrating the importance of the heat loss rate due to the thermal radiation in magnetic hyperthermia

Abnormal resistive switching in electrodeposited Prussian White thin films

Prussian White (PW) layers were deposited on Au/Cr/Si substrates by electrodeposition and characterized by different techniques. Scanning electron microscopy (SEM) images and Raman mapping reveal a uniform and homogeneous deposit while scanning transmission electron microscopy (STEM) images disclose the grain boundary pattern and the thickness of 300 nm of the PW layer. Resistive switching (RS) effect with an ON/OFF ratio of about 102 was observed. The RS mechanism was investigated from the log-log currentvoltage plots. Ionic conduction was observed with an activation energy of 0.4 eV that could be associated with potassium ions as possible charge carriers at the grain boundaries. The endurance characteristics were investigated and a stable abnormal RS was observed for consecutive 500 cycles. Moreover, the retention was also evaluated and the high resistive state (HRS) and low resistive state (LRS) were stable up to 1000 s.The authors acknowledge TESCAN, Zeiss, and WITec for assis-tance during electron microscopy and Raman imaging of the samples and LCME/UFSC for the EDS measurements (LCME-MAT-2021) . We thank D. Hildebrand for his technical assistance. This research was supported by the funding agencies: CNPQ, FINEP, CAPES (finance code 001) , DAAD (project 249302) , FAPESP (process 2013/07296, 2017/20809-0, 2020/04721-8) , and the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding Contract UIDB/04650/2020

Genesis and Health Risk Implications of an Unusual Occurrence of Fibrous NaFe3+-amphibole

Fibrous NaFe3+-amphiboles (winchite, richterite, and magnesioriebeckite) form primarily by alkali metasomatism from magmatic fluids expelled from carbonatite or peralkaline silicate magmas, and have been implicated in high rates of death and disease at Libby, Montana (USA). Fibrous NaFe3+-amphiboles, principally winchite and magnesioriebeckite, are found as fracture-fill veins and as replacement of magmatic hornblende in faulted margins of the dominantly subalkaline, metaluminous Miocene Wilson Ridge pluton, Mohave County, Arizona (USA). Here, the fibrous NaFe3+-amphiboles formed from hypersodic, high-Embedded Image hydrothermal fluids, which circulated through active faults as the pluton cooled through subsolidus temperatures. Halite deposits in adjacent Miocene sedimentary basins are the likely source of Na in the hydrothermal fluid. Amphibole fibers are \u3c1 µm in diameter (typically \u3c0.5 µm), vary from tens to hundreds of microns in length with length-to-width aspect ratios of 20:1 to over 100:1, are capable of dust transport and human inhalation, and should be considered hazardous. Transport and deposition of sediment eroded from primary pluton sources significantly increase the areal distribution of the fibrous amphiboles. Mitigation strategies require an understanding of the geologic settings where hazardous geologic materials are found. Our results suggest that fibrous NaFe3+-amphibole may be present in areas not previously considered at risk for naturally occurring asbestos