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Yu-Ze Chen, Yen-Ting You, Pin-Jung Chen, Dapan Li, Teng-Yu Su, Ling Lee, Yu-Chuan Shih, Chia-Wei Chen, Ching-Chen Chang, Yi-Chung Wang, Cheng-You Hong, Tzu-Chien Wei, Johnny C Ho, Kung-Hwa Wei, Chang-Hong Shen, Yu-Lun Chueh
Selenium (Se) is one of the potential candidates as photodetector because of its outstanding properties such as high photoconductivity (~8x104 S. cm-1), piezoelectricity, thermoelectricity and nonlinear optical responses. Solution phase synthesis becomes an efficient way to produce Se while a contamination issue should be taken into account, deteriorating the electric characteristic of Se. In this work, a facile, controllable approach of synthesizing Se NWs/films via a plasma-assisted growth process was demonstrated at the low substrate temperature of 100 oC...
August 14, 2018: ACS Applied Materials & Interfaces
A P Lira de Farias Freitas, Y Wanderley Cavalcanti, F C Mariz da Costa, L Rangel Peixoto, A M Araújo Maia, K Rovaris Silva, P Meira Bento, D Pita de Melo
AIM: To evaluate the artefact intensity in CBCT images of two alloys used in metal posts scanned using different exposure parameters. METHODOLOGY: The sample consisted of 20 single-rooted teeth divided into two groups for use with either a NiCr post or AgPd post. All teeth were scanned with and without their corresponding metal posts and with and without the presence of an extra restored tooth in the arch. The samples were scanned using CS 9000 3D scanner with two exposure protocols: 85kV 6...
August 14, 2018: International Endodontic Journal
Ehsan Soheyli, Reza Sahraei, Golamreza Nabiyouni, Fereshteh Nazari, Reza Tabaraki, Behnaz Ghaemi
In this paper, an aqueous-based approach is introduced for facile, fast, and green synthesis of gradient-alloyed Fe-doped ZnSe(S)@ZnSe(S) core:shell QDs with intense and stable emission. Co-utilizing of co-nucleation and growth doping strategies, along with systematic optimization of emission intensity, provide a well-controllable/general method to achieve internally doped-quantum dots (d-dots) with intense emission. Results indicated that the alloyed ZnSe(S)@ZnSe(S) core:shell QDs have a gradient structure which consists of the Se-rich core and the S-rich shell...
August 14, 2018: Nanotechnology
Maosheng Guan, Yaobo Hu, Tianxu Zheng, Tianshuo Zhao, Fusheng Pan
Nine kinds of rare-earth free Mg-Al-Sn-Mn magnesium alloys were designed by orthogonal method. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and tension tests were carried out to investigate the microstructures and mechanical properties. As-cast Mg-Al-Sn-Mn alloys have an obvious dendritic structure that is composed of α-Mg, Mg17 Al12 , and Mg₂Sn phases. After hot extrusion, the cast dendrite structure changed into a recrystallized equiaxed grain...
August 13, 2018: Materials
Shuoxun Jin, Tungwai Ngai, Liejun Li, Shian Jia, Tongguang Zhai, Dongjie Ke
In this study, Al-1.00 Mg-0.65 Si-0.24 Cu alloy was solution heat-treated, water-quenched, and then pre-deformed for 5% before aging. The peak hardness and yield strength of the pre-deformed sample with subsequent artificial aging were similar to that of a T6 condition sample. It was also found that the pre-deformation treatment could inhibit the negative influence of natural aging to some degree. After seven days of natural aging, the pre-deformed sample obtained better peak hardness and yield strength upon artificial aging than the sample without pre-deformation...
August 13, 2018: Materials
Bo-Shi Yuan, Ye Zhang, Wei Zhang, Yuan Dong, Guang-Yong Jin
Ablation morphology affects the quality of laser processing. Therefore, the control of ablation morphology is very important. The influence of spot size combination mode on the ablation morphology of aluminum alloy is studied for the first time. Experimental results show that when the nanosecond laser spot is larger, the ablation morphology looks like a bowl-shape, and there is little solidification near the edge. When the nanosecond laser spot is smaller, the shape of the ablation morphology is similar to a hole, and the protuberance is formed near the edge of the cavity...
August 13, 2018: Materials
Hugo P Van Landeghem, Raphaële Danoix, Mohamed Gouné, Sylvie Bordère, Andrius Martinavičius, Peter Jessner, Thierry Epicier, Béatrice Hannoyer, Frédéric Danoix, Abdelkrim Redjaïmia
Atom Probe Tomography (APT), Transmission Electron Microscopy (TEM), and 3D mechanical calculations in complex geometry and anisotropic strain fields were employed to study the role of minor elements in the precipitation process of silicon and chromium nitrides in nitrided Fe⁻Si and Fe⁻Cr alloys, respectively. In nitrided Fe⁻Si alloys, an original sequence of Si₃N₄ precipitation was highlighted. Al⁻N clusters form first and act as nucleation sites for amorphous Si₃N₄ nitrides. This novel example of particle-simulated nucleation opens a new way to control Si₃N₄ precipitation in Fe⁻Si alloys...
August 11, 2018: Materials
Wei Wang, Fengxiang Guo, Zhigang Gai, Tao Zhang, Jianguo Tang, Xuelei Tian, Wenqing Liu
In order to investigate the competitive interaction between nanoparticles and twin, the eutectic Si microstructures in Al⁻10Si (wt. %) base alloys with exclusive and combined addition of Sr and Sb are characterized by combined TEM and atom probe tomography (APT). The chemical short range order in Sb⁻Sb and Sb⁻Sr pairs is revealed by ab initio molecular dynamics simulation, which promotes the formation of clusters and nanoparticles. The coexistence of nanoparticles and twins is observed in Sb containing alloys, with a negative correlation in the corresponding number density, owing to the competitive stacking of precursors and individual atoms at the solid⁻liquid interface...
August 10, 2018: Materials
Lifei Wang, Bo Song, Zhengyong Zhang, Hua Zhang, Tingzhuang Han, Xiaoqing Cao, Hongxia Wang, Weili Cheng
In this study, precompression deformation with a strain level of 5.38% along the transverse direction (TD) at room temperature was conducted on a AZ31 magnesium alloy thin sheet with thickness of 1mm. Then subsequent annealing treatment was carried out at various temperatures (200, 300, 400, and 500 °C) to induce static recrystallization (SRX) and grain growth. The stretch formability was also investigated using the hemispherical test. The results showed that the twinning texture induced by the precompression process was nearly inherited by recrystallized grains after annealing process...
August 10, 2018: Materials
Subir Ghosh, Sylvester Abanteriba, Sherman Wong, Shadi Houshyar
A significant number of hip replacements (HR) fail permanently despite the success of the medical procedure, due to wear and progressive loss of osseointegration of implants. An ideal model should consist of materials with a high resistance to wear and with good biocompatibility. This study aims to develop a new method of grafting the surface of selective laser melted (SLM) titanium alloy (Ti-6Al-4V) with poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC), to improve the surface properties and biocompatibility of the implant...
July 24, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Yolanda S Hedberg, Monika Žnidaršič, Gunilla Herting, Ingrid Milošev, Inger Odnevall Wallinder
The titanium-aluminium (6 wt%)-vanadium (4 wt%) (Ti6Al4V) alloy is widely used as an orthopedic and dental implant material due to its high corrosion resistance in such environments. The corrosion resistance is usually determined by means of electrochemical methods, which may not be able to detect other chemical surface reactions. Literature findings report a synergistic effect of the combination of the abundant protein albumin and hydrogen peroxide (H2 O2 ) on the extent of metal release and corrosion of Ti6Al4V...
August 13, 2018: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
Danyal A Siddiqui, Lidia Guida, Sathyanarayanan Sridhar, Pilar Valderamma, Thomas G Wilson, Danieli C Rodrigues
BACKGROUND: Titanium (Ti) dominates as the material of choice for dental implant systems. Recently, titanium-zirconium alloy (TiZr) and zirconia (ZrO₂ ) have emerged as alternative materials due to higher mechanical strength and lower corrosion susceptibility. Oral pathogenic bacteria can colonize Ti surfaces, leading to surface degradation, which has yet to be investigated on TiZr and ZrO2 . The aim of this study was to compare in vitro oral bacterial adhesion and subsequent surface degradation on commercial Ti, TiZr, and ZrO2 implants...
August 13, 2018: Journal of Periodontology
Caihong Fang, Jun Zhao, Ruibin Jiang, Jing Wang, Guili Zhao, Baoyou Geng
Synthesis of hollow metal nanocrystals is greatly attractive for their high active surface areas, which gives rise to excellent catalytic activity. Taking PdPt alloy nanostructure as an example, we designed a synthetic tactic for the preparation of hollow metal nanostructures by delicate control over the difference in the reduction kinetic of metal precursors. At a high reduction rate difference, the Pd layer forms from the H2 PdCl4 and subsequently is etched, leading to the formation of a hollow space. A solid PdPt structure is achieved when reduction rate of Pd and Pt precursor is comparable...
August 13, 2018: ACS Applied Materials & Interfaces
Jia Lin Zhang, Cheng Han, Zehua Hu, Li Wang, Lei Liu, Andrew T S Wee, Wei Chen
Black phosphorus (BP), first synthesized in 1914 and rediscovered as a new member of the family of 2D materials in 2014, combines many extraordinary properties of graphene and transition-metal dichalcogenides, such as high charge-carrier mobility, and a tunable direct bandgap. In addition, it displays other distinguishing properties, e.g., ambipolar transport and highly anisotropic properties. The successful application of BP in electronic and optoelectronic devices has stimulated significant research interest in other allotropes and alloys of 2D phosphorene, a class of 2D materials consisting of elemental phosphorus...
August 13, 2018: Advanced Materials
Michael M Morlock, Emilie C Dickinson, Klaus-Peter Günther, Dennis Bünte, Valerie Polster
BACKGROUND: Taper corrosion in total hip arthroplasty for bearings with metal heads against polyethylene has developed from an anecdotal observation to a clinical problem. Increased taper wear and even gross taper failure have been reported for one particular design. It is hypothesized that corrosion of the female head taper results in taper widening, allowing the cobalt-chromium head to turn on the stem and wear down the softer titanium alloy by abrasive wear, ultimately causing failure...
July 24, 2018: Journal of Arthroplasty
Kerstin Mayer, Jana Weßing, Thomas F Fässler, Roland A Fischer
Atom-precise, ligand-stabilized metalloid clusters have emerged as outstanding model systems to study fundamental structure and bonding situations of compositionally related extended solid phases. However, this fascinating field of research is still largely restricted to homometallic and pseudo-heterometallic systems of closely related d-block metals. In this article, we will highlight our own, and others', efforts to project the structural and compositional diversity of intermetallics with dissimilar d- and p-block metal combinations, particularly the Zintl and Hume-Rothery phases, onto the molecular level in order to bridge the still gaping chasm between heterometallic molecular coordination chemistry and solid state intermetallics...
August 11, 2018: Angewandte Chemie
Tomoaki Sasaki, Hidetaka Kasai, Eiji Nishibori
Accurate and high reciprocal resolution experimental structure factors of aluminum were determined from a synchrotron powder X-ray diffraction data measured at 30 K with sin θ/λ < 2.31 Å-1 . The structure factors have small deviations from independent atom model in sin θ/λ < 0.83 Å-1 . Theoretical structure factors were prepared using density functional theoretical calculations by full potential linearized augmented plane wave method. The deviation between experimental and theoretical data was also observed at around sin θ/λ ≈ 0...
August 10, 2018: Scientific Reports
Xiang Yan, Yong-Xiang Xu, Yang Wu, Hong Lin
STATEMENT OF PROBLEM: Components fabricated by selective laser melting (SLM) deform because of residual stress, but heat treatment allows the release of that stress and avoids deformation. Although dental cobalt-chromium (Co-Cr) alloy has been specifically designed for SLM, the effects of heat treatment on the metal-ceramic combination of SLM Co-Cr restorations require investigation. PURPOSE: The purpose of this in vitro study was to evaluate the effects of heat treatment on the metal-ceramic combination of SLM Co-Cr alloy...
August 2018: Journal of Prosthetic Dentistry
Philipp Wiechmann, Hannes Panwitt, Horst Heyer, Michael Reich, Manuela Sander, Olaf Kessler
Wide softening zones are typical for welded joints of age hardened aluminium alloys. In this study, the microstructure evolution and distribution of mechanical properties resulting from welding processes of the aluminium alloy EN AW-6082 (AlSi1MgMn) was analysed by both in-situ and ex-situ investigations. The in-situ thermal analyses (TMA) included differential scanning calorimetry (DSC), which was used to characterise the dissolution and precipitation behaviour in the heat affected zone (HAZ) of welded joints...
August 9, 2018: Materials
Zhiyuan Zhu, Yuanfei Cai, Kexing Song, Yanjun Zhou, Jiasheng Zou
The precipitation sequence of a Cu-Ni-Be alloy is: α-Cu supersaturated solid solution → Guinier-Preston (G.P.) zones → metastable γ″ → γ' → stable γ (NiBe) phase. The micro-hardness and electrical conductivity during the aging process were measured. The precipitation characteristics and the distribution of the γ″ phase, under peak aging conditions, were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area diffraction pattern (SADP), and high-resolution transmission electron microscopy (HRTEM)...
August 9, 2018: Materials
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