Nanoparticles exhibiting self-regulating temperature as innovative agents for Magnetic Fluid Hyperthermia

During the last few years, for therapeutic purposes in oncology, considerable attention has been focused on a method called magnetic fluid hyperthermia (MFH) based on local heating of tumor cells. In this paper, an innovative, promising nanomaterial, M48 composed of iron oxide-based phases has been tested. M48 shows self-regulating temperature due to the observable second order magnetic phase transition from ferromagnetic to paramagnetic state. A specific hydrophilic coating based on both citrate ions and glucose molecules allows high biocompatibility of the nanomaterial in biological matrices and its use in vivo. MFH mediator efficiency is demonstrated in vitro and in vivo in breast cancer cells and tumors, confirming excellent features for biomedical application. The temperature increase, up to the Curie temperature, gives rise to a phase transition from ferromagnetic to paramagnetic state, promoting a shortage of the r2 transversal relaxivity that allows a switch in the contrast in Magnetic Resonance Imaging (MRI). Combining this feature with a competitive high transversal (spin-spin) relaxivity, M48 paves the way for a new class of temperature sensitive T2 relaxing contrast agents. Overall, the results obtained in this study prepare for a more affordable and tunable heating mechanism preventing the damages of the surrounding healthy tissues and, at the same time, allowing monitoring of the temperature reached

Mechanical and tribological behavior of nanostructured copper-alumina cermets obtained by Pulsed Electric Current Sintering

Nanostructured Cu–Al2O3 powders obtained by the reduction of CuO with Al in a high energy ball mill were successfully consolidated by Pulsed Electric Current Sintering (PECS). The effect of the composition and microstructure of these PECS Cu–Al2O3 cermets on their strength was investigated. The friction and wear behavior of these cermets were studied under reciprocating sliding against corundum at 23 1C and 50% RH, and compared to the behavior of coarse grained PECS sintered pure copper. The effect of grain size on the coefficient of friction was masked by the formation of a surface tribolayer. The wear depth recorded on Cu–Al2O3 is lesser than half the one on coarse grained copper. Surface and subsurface deformation studied through FIB cross-sections showed that delamination and oxidative wear were active on Cu and Cu–Al2O3 cermets respectively under the current sliding test conditions. PECS Cu–Al2O3 cermets showed a good thermal stability even at 600 1C.status: publishe

Structure and Deformation Behavior of Ti-SiC Composites Made by Mechanical Alloying and Spark Plasma Sintering

Combining high energy ball milling and spark plasma sintering is one of the most promising technologies in materials science. The mechanical alloying process enables the production of nanostructured composite powders that can be successfully spark plasma sintered in a very short time, while preserving the nanostructure and enhancing the mechanical properties of the composite. Composites with MAX phases are among the most promising materials. In this study, Ti/SiC composite powder was produced by high energy ball milling and then consolidated by spark plasma sintering. During both processes, Ti3SiC2, TiC and Ti5Si3 phases were formed. Scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction study showed that the phase composition of the spark plasma sintered composites consists mainly of Ti3SiC2 and a mixture of TiC and Ti5Si3 phases which have a different indentation size effect. The influence of the sintering temperature on the Ti-SiC composite structure and properties is defined. The effect of the Ti3SiC2 MAX phase grain growth was found at a sintering temperature of 1400–1450 °C. The indentation size effect at the nanoscale for Ti3SiC2, TiC+Ti5Si3 and SiC-Ti phases is analyzed on the basis of the strain gradient plasticity theory and the equation constants were defined

Cold Spray Powders and Equipment

Chapter 3A particle shock consolidation encountered in the coldspray (CS) process is defined by a highvelocity impact of powder particles onto the substrate. The particle impact results in the generation of high stresses and strains both in the particles and the substrate. As shown in the basic monographs (Champagne, 2007; Papyrin et al., 2007), the powder material to be sprayed must feature sufficient ductility to ensure particle strains and cold welding without its failure. In some cases (at very high particle velocities) Ti alloy particle melting occurs (Vlcek et al., 2002). However, impact of other metallic powder materials is characterized by high stresses and particle shear strains. Because a lot of information is available on various powders and powder mixtures developed and applied for cold spraying (Jeandin et al., 2014; Moridi et al., 2014, and others), the goal of this chapter is to describe and discuss the concept of CS material selection, basic criteria for evaluation of its suitability for cold spraying, and particle behavior during the deposition process (acceleration and formation of interfaces)Book chapterPaolo Matteazzi , Alberto Colella , Volf Leshchynsky , Kazuhiko Sakaki et al. "Chapter 3. Cold Spray Powders and Equipment". Cold Gas Dynamic Spray. Roman Gr. Maev, Volf Leshchynsky, eds. CRC Press, 2016, p.95-118.boo

Effect of C (graphite) doping on the H2 sorption performance of the Mg – Ni storage system.

Binary Mg – Ni mixtures and ternary Mg – Ni – C (graphite) samples with fixed proportions of metals (Mg 85 %: Ni 15 % by weight) and amount of C increasing in increments of 5 wt % from 5 wt % to 15 wt % were prepared by high energy ball milling (BM) in Ar for tBM = 2 h. The purpose of the study was to evaluate the effect of C addition on the reactivity, the sorption activation and the storage performance of the Mg - Ni system. Increasing the amount of C had the effect of decreasing (from 10 to 3) the number of cycles needed for activation (performed at 623 K and 40 bar/0.9 bar charging/discharging H2 pressure). After full activation, the 5 wt % C-containing sample exhibited the best absorption kinetics performance: the average rate to charge up to 5 wt % H2 was about 3 times higher than that observed for the undoped sample. Unfortunately, increasing the amount of C had a negative impact on the desorption behaviour, causing an increase in the dehydrogenation activation energy and a decrease in the discharging rates. Within the present study, C reacted neither with H2 nor with the H2 active phases (the two discharged phases Mg and Mg2Ni and the related hydrides) and consequently did not lead to variation in the sorption enthalpies of the Mg-Ni system. But, its presence did cause a small increase (4 K at 0.9 bar H2) in the minimum desorption temperatures of the hydrides and a consequent minor decrease (0.2 bar) in the equilibrium pressures. The best sorption properties were obtained for the 5 wt % C-sample, that on the whole worked better than the binary mixture

Synergetic effect of C (graphite) and Nb2O5 on the H2 sorption properties of the Mg-MgH2 system

Ternary Mg–Nb2O5 – graphitic C mixtures (molar ratio % = 97.5:0.5:2.0) were prepared by high-energy ball milling (BM) under Ar for different times (from 0.25 h to 4 h) and thoroughly characterized by manometric, calorimetric, X-ray powder diffraction, and scanning electron microscopy analyses. The aims of the work were: - to assess the effect of the simultaneous presence of the two dopants on the reactivity and the sorption properties of the Mg–MgH2 system; - to study the influence of the milling time on the performance of the mixtures. Neither milling nor the high temperature/high pressure treatments led to reactions among the components of the mixtures, and Mg was the only hydrogen active phase. After 4 activation cycles at 623 K and 35 bar/1 bar charging/discharging pressure, the mixture milled for 1 h was the best performing one: it reversibly charged up to 6.8 wt% H2 with absorption/desorption rates 64/4.5 times higher than those of a pure Mg sample BM for the same time and activation energies 3.6/2 times lower. The desorption temperature and the dehydrogenation enthalpy of the ternary mixture were respectively 40 K and 4 kJ/mol H2 lower than those of pure MgH2