Browsing by Subject "Energy dispersive X ray spectroscopy"

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    Compositional homogeneity in a medical-grade stainless steel sintered with a Mn-Si additive
    (Elsevier, 2012-06-09) Salahinejad, E.; Hadianfard, M.J.; Ghaffari, M.; Mashhadi, S.B.; Okyay, Ali Kemal
    In this paper, chemical composition uniformity in amorphous/ nanocrystallization medical-grade stainless steel (ASTM ID: F2581) sintered with a Mn-Si additive was studied via scanning electron microscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy. The results show that as a result of sintering at 1000 °C, no dissociation of Mn-Si additive particles embedded in the stainless steel matrix occurs. In contrast, sintering at 1050 °C develops a relatively homogeneous microstructure from the chemical composition viewpoint. The aforementioned phenomena are explained by liquation of the Mn-Si eutectic additive, thereby wetting of the main powder particles, penetrating into the particle contacts and pore zones via capillary forces, and providing a path of high diffusivity.
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    Nanoscale selective area atomic layer deposition of TiO2 using e-beam patterned polymers
    (Royal Society of Chemistry, 2016) Haider A.; Yilmaz, M.; Deminskyi, P.; Eren, H.; Bıyıklı, Necmi
    Here, we report nano-patterning of TiO2via area selective atomic layer deposition (AS-ALD) using an e-beam patterned growth inhibition polymer. Poly(methylmethacrylate) (PMMA), polyvinylpyrrolidone (PVP), and octafluorocyclobutane (C4F8) were the polymeric materials studied where PMMA and PVP were deposited using spin coating and C4F8 was grown using inductively coupled plasma (ICP) polymerization. TiO2 was grown at 150 °C using tetrakis(dimethylamido) titanium (TDMAT) and H2O as titanium and oxygen precursors, respectively. Contact angle, scanning electron microscopy (SEM), spectroscopic ellipsometry, and X-ray photoelectron spectroscopy (XPS) measurements were performed to investigate the blocking/inhibition effectiveness of polymer layers for AS-ALD of TiO2. TiO2 was grown with different numbers of growth cycles (maximum = 1200 cycles) on PMMA, PVP, and C4F8 coated substrates, where PMMA revealed complete growth inhibition up to the maximum number of growth cycles. On the other hand, PVP was able to block TiO2 growth up to 300 growth cycles only, whereas C4F8 showed no TiO2-growth blocking capability. Finally, mm-, μm-, and nm-scale patterned selective deposition of TiO2 was demonstrated exploiting a PMMA masking layer that has been patterned using e-beam lithography. SEM, energy-dispersive X-ray spectroscopy (EDX) line scan, EDX elemental mapping, and XPS line scan measurements cumulatively confirmed the self-aligned deposition of TiO2 features. The results presented for the first time demonstrate the feasibility of achieving self-aligned TiO2 deposition via TDMAT/H2O precursor combination and e-beam patterned PMMA blocking layers with a complete inhibition for >50 nm-thick films.
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    Toxicity of internalized laser generated pure silver nanoparticles to the isolated rat hippocampus cells
    (SAGE, 2017-02) Kursungoz, C.; Taş, S. T.; Sargon, M. F.; Sara, Y.; Ortaç, B.
    Silver nanoparticles (AgNPs) are the most commonly used nanoparticles (NPs) in medicine, industry and cosmetics. They are generally considered as biocompatible. However, contradictory reports on their biosafety render them difficult to accept as 'safe'. In this study, we evaluated the neurotoxicity of direct AgNP treatment in rat hippocampal slices. We produced pure uncoated AgNPs by a pulsed laser ablation method. NP characterization was performed by Ultraviolet (UV) visible spectrophotometer, scanning electron microscope, transmission electron microscope (TEM) and energy-dispersive X-ray spectroscopy. Rat hippocampal slices were treated with AgNPs for an hour. AgNP exposure of hippocampal tissue resulted in a significant decrease in cell survival in a dose-dependent manner. Our TEM results showed that AgNPs were distributed in the extracellular matrix and were taken into the cytoplasm of the neurons. Moreover, we found that only larger AgNPs were taken into the neurons via phagocytosis. This study showed that the pure AgNPs produced by laser ablation are toxic to the neural tissue. We also found that neurons internalized only the large NPs by phagocytosis which seems to be the major mechanism in AgNP neurotoxicity.