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4725 KiB

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Effects of Surface Structure and Chemical Composition of Binary Ti Alloys on Cell Differentiation

by Ok-Sung Han, Moon-Jin Hwang, Yo-Han Song, Ho-Jun Song and Yeong-Joon Park

Metals 2016, 6(7), 150; https://doi.org/10.3390/met6070150 - 04 Jul 2016

Cited by 2 | Viewed by 4136

Binary Ti alloys containing Fe, Mo, V and Zr were micro-arc oxidized and hydrothermally treated to obtain micro- and nano-porous layers. This study aimed to investigate cell differentiation on micro and micro/nanoporous oxide layers of Ti alloys. The properties of the porous layer [...] Read more.

Binary Ti alloys containing Fe, Mo, V and Zr were micro-arc oxidized and hydrothermally treated to obtain micro- and nano-porous layers. This study aimed to investigate cell differentiation on micro and micro/nanoporous oxide layers of Ti alloys. The properties of the porous layer formed on Ti alloys were characterized by X-ray diffraction pattern, microstructural and elemental analyses and inductively coupled plasma mass spectrometry (ICP-MS) method. The MTT assay, total protein production and alkaline phosphatase (ALPase) activity were evaluated using human osteoblast-like cells (MG-63). Microporous structures of micro-arc oxidized Ti alloys were changed to micro/nanoporous surfaces after hydrothermal treatment. Micro/nanoporous surfaces consisted of acicular TiO₂ nanoparticles and micron-sized hydroxyapatite particles. From ICP and MTT tests, the Mo and V ions released from porous oxide layers were positive for cell viability, while the released Fe ions were negative for cell viability. Although the micro/nanoporous surfaces led to a lower total protein content than the polished and microporous Ti surfaces after cell incubation for 7 days, they caused higher ALPase activities after 7 days and 14 days of incubation except for V-containing microporous surfaces. The micro/nanoporous surfaces of Ti alloys were more efficient in inducing MG-63 cell differentiation. Full article

(This article belongs to the Special Issue Refractory Metals and Alloys)

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4827 KiB

Open AccessArticle

Effect of BaO Addition on Densification and Mechanical Properties of Al₂O₃-MgO-CaO Refractories

by Lei Liu, Min Chen, Lei Xu, Xueliang Yin and Wenjie Sun

Metals 2016, 6(4), 84; https://doi.org/10.3390/met6040084 - 11 Apr 2016

Cited by 13 | Viewed by 4963

Abstract

Considering the requirement for a reduction of refractory consumption, the present work investigated the fabrication of Al₂O₃-MgO-CaO-based refractory with BaO addition by means of solid-state reaction sintering. The effect of BaO addition on densification and the properties of the [...] Read more.

Considering the requirement for a reduction of refractory consumption, the present work investigated the fabrication of Al₂O₃-MgO-CaO-based refractory with BaO addition by means of solid-state reaction sintering. The effect of BaO addition on densification and the properties of the refractory were also discussed. Results indicated that the formation of calcium hexaluminate (CaO·6Al₂O₃, or CA₆) grains with a high aspect ratio in the alumina-rich zone depressed the densification of the sample without BaO addition, resulting in a higher apparent porosity of 21.2%. When 6 wt. % BaO was added, a new phase of Ba₂Mg₆Al₂₈O₅₀ (BAM) with a lower aspect ratio was formed and the densification of the sample with an apparent porosity of 5.52% was promoted. In addition, mechanical performance was significantly improved due to an increase in compactness and modification of the microstructure. The cold compressive strength increased from 348 MPa to 569 MPa and the flexural strength increased from 178 MPa to 243 MPa by addition of 6 wt. % BaO. Meanwhile, the breadth of the widest crack after the thermal shock test decreased from 7 μm to 1 μm in the refractory. Full article

(This article belongs to the Special Issue Refractory Metals and Alloys)

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1120 KiB

Open AccessFeature PaperArticle

Spectral Shift Amplification and Polarization-Controlled Spectral Shift with Silver Metal

by Pin Han and Yung-Chieh Tseng

Metals 2016, 6(1), 7; https://doi.org/10.3390/met6010007 - 26 Dec 2015

Cited by 3 | Viewed by 4697

Abstract

The spectral shift amplification effect and polarization-controlled spectral shifts are studied using silver (Ag) metal. The spectral shift amplification factor can be doubled by using silver compared with using water. The solid Ag metal surface also provides orientation freedom for polarization-controlled spectral shifts, [...] Read more.

The spectral shift amplification effect and polarization-controlled spectral shifts are studied using silver (Ag) metal. The spectral shift amplification factor can be doubled by using silver compared with using water. The solid Ag metal surface also provides orientation freedom for polarization-controlled spectral shifts, benefiting data transmission applications in any direction. The liquid water interface provides only limited direction at the Brewster angle. Besides those advantages, the higher reflectivity of Ag reflects higher spectral intensity, which makes the signal easier to detect. The spectral switch phenomenon that depends on the central wavelength variation is also presented. Full article

(This article belongs to the Special Issue Refractory Metals and Alloys)

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