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Paul Johan Høl, Nils R Gjerdet, Torbjörn Jonung
Intra-arterial stenosis due to atherosclerosis is often treated with endovascular balloon dilatation with a metal stent. Restenosis is common and is frequently treated with a new stent placed inside the existing one or the stents are placed with overlap to cover a larger area of the vessels. Observations of stent fractures, stent compression, accumulation of immunocompetent cells around stents have suggested the possibility of immunologic reactions to substances released from stents. An accelerated corrosion model was developed to study corrosion behaviour of commonly used surgical peripheral stents...
February 4, 2019: Journal of the Mechanical Behavior of Biomedical Materials
Yujuan Zhang, Weiyi Xia, Yabei Wu, Peihong Zhang
MXenes are a large family of layered transition metal carbide/nitride materials that possess a number of desired properties such as flexible chemical composition, high mechanical strength, and excellent structural stability. Although MXene based semiconductors have attracted considerable recent research attention in the search of novel 2D electronic materials, accurate understanding of their electronic properties has not been established. In this work, we carry out fully converged GW quasiparticle calculations for M2CO2 (M = Hf, Zr, and Ti) MXene based 2D semiconductors and alloys using newly developed accelerated GW methods...
February 15, 2019: Nanoscale
Shengzhe Wu, Su Xu, Tatiana L Zinenko, Vladimir V Yachin, Sergey L Prosvirnin, Vladimir R Tuz
We propose a novel design of a 3D chiral metasurface behaving as a spatial polarization converter with asymmetric transmission. The metasurface is made of a lattice of metallic one-and-a-half-pitch helical particles. The proposed metasurface exhibits a dual-band asymmetric transmission accompanied by the effect of complete polarization conversion. Regarding circularly polarized waves, the metasurface demonstrates a strong circular dichroism. A prototype of the metasurface is manufactured for the quasi-optic experiment by using a 3D printing technique utilizing a cobalt-chromium alloy, which exhibits good performances against thermal fatigue and corrosion at high temperatures...
February 15, 2019: Optics Letters
Sergio Giraldo, Zacharie Jehl, Marcel Placidi, Victor Izquierdo-Roca, Alejandro Pérez-Rodríguez, Edgardo Saucedo
The latest progress and future perspectives of thin film photovoltaic kesterite technology are reviewed herein. Kesterite is currently the most promising emerging fully inorganic thin film photovoltaic technology based on critical raw-material-free and sustainable solutions. The positioning of kesterites in the frame of the emerging inorganic solar cells is first addressed, and the recent history of this family of materials briefly described. A review of the fast progress achieved earlier this decade is presented, toward the relative slowdown in the recent years partly explained by the large open-circuit voltage (VOC ) deficit recurrently observed even in the best solar cell devices in the literature...
February 14, 2019: Advanced Materials
Kulbir Kaur Ghuman, Kota Tozaki, Masaaki Sadakiyo, Sho Kitano, Takashi Oyabe, Miho Yamauchi
Despite many advancements, an inexpensive ammonia synthesis catalyst free from hydrogen and nitrogen poisoning, and capable of synthesizing ammonia under mild conditions is still unknown and is long sought-after. Here we present an active nanoalloy catalyst, RuFe, formed by alloying highly active Ru and inexpensive Fe, capable of activating both N2 and H2 without blocking the surface active sites and thereby overcoming the major hurdle faced by the current best performing pure metal catalysts. This novel RuFe nanoalloy catalyst operates under milder conditions than the conventional Fe catalyst and is less expensive than the so far best performing Ru-based catalysts providing additional advantages...
February 15, 2019: Physical Chemistry Chemical Physics: PCCP
Seung-Pyo Kim, Han-Cheol Choe
In this study, functional elements coatings on the plasma electrolytic oxidation (PEO)-treated Ti-6Al-4V alloy by electrochemical precipitation method were investigated. Ti-6Al-4V ELI disks were used as specimens for PEO and HA coating. The applied voltage and time were selected to be 280 V and 3 minutes for PEO treatment, respectively. The electrochemical precipitation on the Ti-6Al-4V alloy was carried out using cyclic voltammetry with cycle of 3, 5, 10, and 20 from -1.5 V to 0 V (vs. SCE electrode) in electrolyte containing Ca, P, Mg, Mn, Sr, Zn, and Si ions by cyclic voltammetry after PEO treatment...
July 1, 2019: Journal of Nanoscience and Nanotechnology
Yang-Kyun Park, Dong-Geun Lee
Ti-39Nb-6Zr-0.45Al alloy was developed for biological applications as exchangeable hard tissue. This alloy has very low elastic modulus, but lower strength than Ti-6Al-4V alloy. This study was performed for improving the strength by various heat treatments and microstructural characteristics and mechanical properties of Ti-39Nb-6Zr-0.45Al alloy were investigated. Heat treatments were conducted at 350 °C, 400 °C, 450 °C, 500 °C, 550 °C and 600 °C, followed by water quenching. Microstructures of Ti-39Nb-6Zr-0...
July 1, 2019: Journal of Nanoscience and Nanotechnology
Byungha Choi, Injoon Son
In the present study, an acidic palladium-nickel alloy plating solution was prepared with ethylenediamine as the complexing agent, and the physical properties of the alloy plating layer were investigated. The palladium-nickel alloy plating layer could be deposited over a broad range of current densities as the deposition potential of palladium in the solution containing ethylenediamine significantly shifted toward the base direction and the value was similar to that of nickel. X-ray diffraction patterns confirmed that the palladium-nickel alloy existed as a single-phase solid solution in the prepared alloy...
July 1, 2019: Journal of Nanoscience and Nanotechnology
So-Hyun Gong, Ji-Young Lee, Yoon-Jun Kim
The 7000 series aluminum alloys are widely used in the aerospace and automotive industries due to their high strength and low weight. Those advantages of the 7000 series aluminum alloys, however, are hampered by an occurrence of the hydrogen embrittlement and/or stress corrosion cracking under certain heat treatment conditions such as natural or artificial aging treatment. Herein, we utilize an atom-probe tomography (APT) and a transmission electron microscopy (TEM) to study the microstructural evolution of a naturally aged commercial 7075-T4 grade aluminum alloy...
July 1, 2019: Journal of Nanoscience and Nanotechnology
Yeajin Kim, Heon-Cheol Shin, Sungmo Moon
This paper reports three different anodic oxidation behaviors of AZ31 Mg alloy in NaOH solutions, depending on the applied current density and concentration of NaOH between 0.1 M and 0.6 M. When applied current density is lower than about 30 mA/cm², dark anodic film was formed with a very low film formation voltage of less than 6 V and it was found to grow with anodizing time. If applied current density is higher than a critical value about 30 mA/cm², bright metallic surface appearance with small number of pits and/or trenches was obtained...
July 1, 2019: Journal of Nanoscience and Nanotechnology
Sung Hwa Bae, Incheol Chol, Injoon Son
This study investigated the effects of process conditions (anodization time, coloring treatment time, dye concentration) on the color of dye-treated anodized aluminum alloy 5052 (AA5052). The color change of the anodic layers and amount of dye adsorbed were quantitatively analyzed using a UV-vis spectrophotometer. The color of the anodic layer turned darker as the anodizing time, coloring treatment time, and dye concentration increased due to the amount of dye adsorbed by the layers. As the anodizing time increased, the thickness of the anodic layers also increased, and a growth in the number of nanopore sites resulted in a greater amount of dye being adsorbed, causing the darkening of the color...
July 1, 2019: Journal of Nanoscience and Nanotechnology
Oleh Yaskiv, Iryna Pohrelyuk, Waheed Ali Abro, Muhammad Ali Abro, Kun Sang Lee, Dong Bok Lee
Nitrided and oxynitrided coatings that formed on α alloy (c.p.-Ti), near- α alloy (Ti-2.1Al-2.5Zr), ( α + β ) alloy (Ti-6Al-4V), and β alloy (Ti-6Al-2Zr-1Mo-1V) were microstructurally characterized. The nitriding at 950 °C and P N₂ ═ 105 Pa for 5 h formed TiN, Ti₂N, and α -Ti(N) layers from the surface. The nitriding tendency increased in the order of β alloy, ( α + β ) alloy, near- α alloy, and α alloy. The Ti-N coatings transformed to Ti-N-O coatings when the nitrided alloys were exposed to P O₂ ═ 10-2 Pa during cooling at the final stage of the nitriding...
July 1, 2019: Journal of Nanoscience and Nanotechnology
Richa Baronia, Jyoti Goel, Garima Gautam, Dinesh Singh, Sunil K Singhal
Incomplete methanol oxidation and rapid activity degradation of electro-catalysts are key barriers to successful commercialization of direct methanol fuel cell (DMFC). To address these problems, we report the synthesis of platinum-copper (PtCu) alloy nanoparticles supported on nitrogen doped reduced graphene oxide (N-rGO) as the anode catalyst for the efficient electro-oxidation of methanol. Catalysts with varying molar ratios of PtCu were fabricated using impregnation reduction method and their electrochemical performance was compared with the commercially available Pt/C (20 wt%) anode catalyst...
July 1, 2019: Journal of Nanoscience and Nanotechnology
Shuai Zhang, Feng Chen, Yuchen Chi, Zhenhua Dan, Fengxiang Qin
Novel Ti-Cu-O nanotubes with the diameter of approximately 22 nm, the length of about 360 nm and the wall thickness of approximately 6 nm, were in-situ fabricated by one-step anodic oxidation of Ti60 Cu40 amorphous alloy in the ethylene glycol containing F- . The Ti-Cu-O nanotubes exhibited superior electrocatalytic performance for glucose oxidation with an ultrahigh sensitivity of 403.9 μ A cm-2 mM-1 in a linear range covering from 10 μ M to 0.2 mM and low detection limit of 1.40 μ M (at signal/noise ratio (S/N) = 3) at the potential of 0...
July 1, 2019: Journal of Nanoscience and Nanotechnology
Yu-Jin Hwang, Dong-Geun Lee
For metals to be used as biomaterials, there must not be harmful reaction between the corrosion product of metal or eluted ion, and bio-tissue. Titanium is one of the excellent bio-compatible materials and generally it has tendency to have a small amount elution of Ti ions inside the body. Titanium alloy need to have low elastic modulus for reducing the stress shield effect. Ti-39Nb-6Zr alloy which is consist of biocompatible element such as Nb and Zr, has low elastic modulus with below 60 GPa, but it shows lower yield stress and tensile stress compared with Ti-6Al-4V alloy...
July 1, 2019: Journal of Nanoscience and Nanotechnology
Dinesh Rokaya, Viritpon Srimaneepong, Jiaqian Qin, Krisana Siraleartmukul, Vilailuck Siriwongrungson
The aim of this study was to evaluate the mechanical and tribological properties of graphene oxide/silver nanoparticle (GO/AgNP) coated medical grade nickel-titanium (NiTi) alloy. The alloy substrates were coated using electrophoretic deposition at 30 V for 1, 5, and 10 min and were characterized by SEM, Raman spectroscopy, EDS, and surface profilometer. Mechanical and tribological tests were performed for hardness, Young's modulus, and friction coefficient. The data were analyzed using the Kruskal-Wallis test at a significance level of 0...
July 1, 2019: Journal of Nanoscience and Nanotechnology
Ming Ma, Rongxin Wan, Huanhuan Gong, Xiaofei Lv, Shanshan Chu, Dejun Li, Hanqing Gu, Cheng Peng
To determine the short- and long-term antibacterial properties of a novel biomedical titanium alloy to ensure excellent biocompatibility of the TiN/Ag multilayers loaded with different doses of Ag+ . First, nanosized TiN/Ag multilayers were accumulated onto titanium alloy (Ti-6Al-4V) substrates via multi-arc ion plating. Then, the multilayers were implanted with different doses of silver ions (1×1017 ions/cm², 1×1018 ions/cm², 5×1016 ions/cm², and 5×1017 ions/cm²). Both short- and long-term antibacterial properties against Streptococcus mutans and Staphylococcus aureus were assessed via unique methods...
July 1, 2019: Journal of Nanoscience and Nanotechnology
Giulio Marchese, Emilio Bassini, Alberta Aversa, Mariangela Lombardi, Daniele Ugues, Paolo Fino, Sara Biamino
Hastelloy X (HX) is a Ni-based superalloy which is employed to produce gas turbine and gas-cooled reactor sectors due to its outstanding oxidation resistance and high tensile strength at high temperatures. This alloy can be processed by laser powder bed fusion (LPBF) fabricating complex geometries in a single step. However, post-processing thermal treatments must be applied to generate a suitable microstructure for high-temperature applications. The investigation reports the microstructure evolution of LPBF HX samples under specific post-processing treatments...
February 5, 2019: Materials
Sigrun Eick, Naida Gadzo, Manuel Tacchi, Anton Sculean, Jan Potempa, Andreas Stavropoulos
The study investigated in vitro the effect of Porphyromonas gingivalis and its cysteine proteases (gingipains) on epithelial cell adhesion to titanium-zirconium alloy surfaces. Titanium-zirconium discs with a standard machined (M) or chemically modified hydrophilic surface (modM) were coated with lamin-5 and incubated with telomerase-inactivated gingival keratinocytes (TIGK). Three P. gingivalis strains or gingipains were either added simultaneously with TIGK or after TIGK cells were already attached to the disks...
February 14, 2019: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
S C Dayan, B Kiseri, B Gencel, A Kurt
The aim of this study was to assess the internal and marginal discrepancies of chromium-cobalt (Co/Cr) copings fabricated using different techniques. A typodont molar tooth was prepared and replicated in die stone and scanned. Forty Co-Cr alloy copings were produced using four different production techniques: conventional casting (Cgroup), direct metal laser sintering (DMLS-group), micro-stereolithography/casting combination (μSLA-group), and computer-aided milling (M-group) (n = 10). The internal and marginal discrepancies at various reference points were determined via digital microscopy...
February 5, 2019: European Journal of Prosthodontics and Restorative Dentistry
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