Study of the Mechanochemical Reduction of Ilmenite Concentrate by Addition of Aluminum

Mechanochemical reduction of ilmenite concentrate $(FeTiO_{3})$ with elemental aluminum powder was performed by high-energy milling in an industrial eccentric vibratory ball mill ESM 656-0.5 ks (Siebtechnik, Germany). The mechanochemically reduced ilmenite with various times of milling was characterized by X-ray diffraction analysis, which confirmed the presence of the $Al_2O_3$ and $Fe_2Ti$ phases after 120 min of milling. Thermal analysis evidenced the completion of a mechanochemical reduction during milling. After 360 min of milling, the $Fe_2Ti$ phase decomposed to α-(Fe,Ti) alloy, which was proven by $\text{}^{57}Fe$ Mössbauer spectroscopy. X-ray photoelectron spectroscopy detected the amorphous TiO phase in product after mechanochemical reduction, which is in accordance with thermodynamic prediction. Decreasing of specific surface area after 60 min of milling resulted from growing layers of the solid products of $FeTiO_3$ mechanochemical reduction

Physico-Chemical and Biological Properties of Arsenic Sulfide (As55S45As_{55}S_{45}) Nanosuspension Prepared by Milling

Nanosuspension based on melt-quenched arsenic sulfide of nominal $As_{55}S_{45}$ composition was prepared by nanomilling and tested as potential anticancer drug. Polyvinylpyrrolidone was used as steric stabilizer and inhibitor of agglomeration. Individual nanoparticles had average size of 192 nm (determined by photon cross-correlation spectroscopy) and had several times better dissolution ability in comparison with bulk $As_{55}S_{45}$. Effect of nanomilling is shown to be associated with formation of arsenic sulfide crystalline nanoparticles and free-volume entities located at the interface between nanoparticles and surrounding matrix as it follows from positron annihilation measurements. Cytotoxicity tests were performed using human melanoma cell line Bowes and confirmed high toxicity of the studied nanosuspension

Mechanochemical Synthesis and Characterization of II-VI Nanocrystals: Challenge for Cytotoxicity Issues

CdSe@ZnS nanocrystals have been prepared by a two-step solid state mechanochemical synthesis. CdSe prepared from elements in the first step is mixed with ZnS synthesized from zinc acetate and sodium sulfide in the second step. The crystallite size of the new type CdSe@ZnS nanocrystals determined by X-ray diffraction Rietveld refined method was 35 nm and 10 nm for CdSe and ZnS, respectively. Energy dispersive/transmission electron microscopy/energy dispersive spectroscopy methods show good crystallinity of the nanoparticles and scanning electron microscopy elemental mapping illustrate consistent distribution of Cd, Se, Zn and S elements in the bulk of samples. UV-VIS spectra show an onset at 320 nm with calculated bandgap 3.85 eV. This absorption arises from the vibration modes of Zn-S bonds. The nanocrystals show the blue shift from the bandgap of bulk ZnS (3.66 eV). The synthesized CdSe@ZnS nanocrystals have been tested for dissolution, cytotoxicity and L-cysteine conjugation. The dissolution of Cd was less than 0.05 μg $mL^{-1}$ (in comparison with 0.8 μg $mL^{-1}$ which was evidenced for CdSe alone). The very low cytotoxic activity for selected cancer cell lines has been evidenced. CdSe@ZnS nanocrystals coated with L-cysteine are water-soluble and have a great potential in biomedical engineering as fluorescent labels