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electron beam melting

Lockie Yuen, Cameron McLucas
The X-ray focal spot and the centre of the flattening filter should be placed as close as possible to the central axis (CAX) on a linear accelerator (linac) to produce a radially symmetric beam. The aim of this study is to devise a method to easily optimise the focal spot position of Varian linac photon beams generated with a flattening filter. A simple and robust jig was designed and built to be inserted into the largest electron applicator. Accessory and jaw position interlocks were overridden to enable photon beam operation...
April 13, 2017: Australasian Physical & Engineering Sciences in Medicine
Meng Zhang, Yuxue Liu, Jian Yang, Hancheng Zhu, Duanting Yan, Xinyang Zhang, Chunguang Liu, Changshan Xu, Hong Zhang
Encaged-OH(-)-free Ca12(1-x)Sr12xAl14O33:0.1%Gd(3+) conductive phosphors were prepared through a melt-solidification process in combination with a subsequent heat treatment. Absorption spectra showed that the maximum encaged-electron concentration was increased to 1.08 × 10(21) cm(-3) through optimizing the doping amount of Sr(2+) (x = 0.005). Meanwhile, FTIR and Raman spectra indicated that pure Ca11.94Sr0.06Al14O33:0.1%Gd(3+) conductive phosphor without encaged OH(-) and C2(2-) anions was acquired. For the conductive powders heat-treated in air for different times, the encaged-electron concentrations were tuned from 1...
March 29, 2017: Physical Chemistry Chemical Physics: PCCP
L E Murr
Implant history extends more than 4000 years in antiquity, with biocompatible alloy implants extending over only 70 years. Over the past several decades, total hip and knee replacements of Ti-6Al-4V and Co-Cr-Mo alloys have exhibited post implantation life spans extending over 15 years; limited by infection, loosening, stress-shielding-related bone resorption and other mechanical failures. With the advent of additive manufacturing technologies, such as electron beam melting (EBM) over the past decade, personalized, patient-specific; porous (open-cellular) implant components can be manufactured, and the integration of chemical, biological and mechanical methods is able to optimize strategies for improving long-term clinical outcomes...
February 27, 2017: Journal of the Mechanical Behavior of Biomedical Materials
Arixin Bo, Jose Alarco, Huaiyong Zhu, Eric R Waclawik, Haifei Zhan, YuanTong Gu
Construction of nanoarchitectures requires techniques like joint formation and trimming. For ceramic materials, however, it is extremely difficult to form nanojoints by conventional methods like merging. In this work, we demonstrate that ceramic titanate nanowires (NWs) can be joined by spot melting under electron beam (e-beam) irradiation (EBI). The irradiation fuses the contacted spot of titanate NWs yielding an intact nanojoint. Nanojoints with different morphologies can be produced. The joint structures consist of titanium dioxide (TiO2) rutile, anatase, and titanate phases in the direction away from the e-beam melting spot...
March 2, 2017: ACS Applied Materials & Interfaces
Jukka T Tuomi, Roy V Björkstrand, Mikael L Pernu, Mika V J Salmi, Eero I Huotilainen, Jan E H Wolff, Pekka K Vallittu, Antti A Mäkitie
Custom-designed patient-specific implants and reconstruction plates are to date commonly manufactured using two different additive manufacturing (AM) technologies: direct metal laser sintering (DMLS) and electron beam melting (EBM). The purpose of this investigation was to characterize the surface structure and to assess the cytotoxicity of titanium alloys processed using DMLS and EBM technologies as the existing information on these issues is scarce. "Processed" and "polished" DMLS and EBM disks were assessed...
March 2017: Journal of Materials Science. Materials in Medicine
B R Jany, N Gauquelin, T Willhammar, M Nikiel, K H W van den Bos, A Janas, K Szajna, J Verbeeck, S Van Aert, G Van Tendeloo, F Krok
Nano-sized gold has become an important material in various fields of science and technology, where control over the size and crystallography is desired to tailor the functionality. Gold crystallizes in the face-centered cubic (fcc) phase, and its hexagonal closed packed (hcp) structure is a very unusual and rare phase. Stable Au hcp phase has been reported to form in nanoparticles at the tips of some Ge nanowires. It has also recently been synthesized in the form of thin graphene-supported sheets which are unstable under electron beam irradiation...
February 14, 2017: Scientific Reports
Yingxuan Li, Ling Zang, Daniel L Jacobs, Jie Zhao, Xiu Yue, Chuanyi Wang
Experimental study of the atomic mechanism in melting and freezing processes remains a formidable challenge. We report herein on a unique material system that allows for in situ growth of bismuth nanoparticles from the precursor compound SrBi2Ta2O9 under an electron beam within a high-resolution transmission electron microscope (HRTEM). Simultaneously, the melting and freezing processes within the nanoparticles are triggered and imaged in real time by the HRTEM. The images show atomic-scale evidence for point defect induced melting, and a freezing mechanism mediated by crystallization of an intermediate ordered liquid...
February 13, 2017: Nature Communications
Natale Francaviglia, Rosario Maugeri, Antonino Odierna Contino, Francesco Meli, Vito Fiorenza, Gabriele Costantino, Roberto Giuseppe Giammalva, Domenico Gerardo Iacopino
BACKGROUND: Cranioplasty represents a challenge in neurosurgery. Its goal is not only plastic reconstruction of the skull but also to restore and preserve cranial function, to improve cerebral hemodynamics, and to provide mechanical protection of the neural structures. The ideal material for the reconstructive procedures and the surgical timing are still controversial. Many alloplastic materials are available for performing cranioplasty and among these, titanium still represents a widely proven and accepted choice...
2017: Acta Neurochirurgica. Supplement
J Ha, A Gallogly, J Cui, R Jennelle
PURPOSE: The aim of this work is to show that Field's metal can be used as a viable alternative material to lead-based low-melting temperature alloys (e.g., Cerrobend) for electron beam inserts and blocks. The goal is to eliminate exposure risks associated with lead and cadmium. METHODS: Field's metal (51% Indium, 32.5% Bismuth, 16.5% Tin) is a low-melting point eutectic alloy, and is proposed as a lead-free replacement for Cadmium-free alloy (52.5% Bismuth, 32% Lead, 15...
June 2016: Medical Physics
B J Zhao, H Wang, R Z Yan, C Wang, R X Li, M Hu
Objective: To evaluate the surface characteristics and cytocompatibility of Ti-6Al-4V alloy fabricated using select laser melting (SLM) and electron beam melting (EBM) technique. Methods: Ti-6Al-4V alloy specimens were fabricated with SLM and EBM. A wrought form of Ti-6Al-4V alloy was used as a control. Its properties were evaluated using component analysis, contact angle test, surface roughness, surface topography, cell ultrastructure, cell attachment and proliferation observation, metal ion precipitation examination...
December 9, 2016: Zhonghua Kou Qiang Yi Xue za Zhi, Zhonghua Kouqiang Yixue Zazhi, Chinese Journal of Stomatology
Anders Palmquist, Furqan A Shah, Lena Emanuelsson, Omar Omar, Felicia Suska
This paper investigates the application of X-ray micro-computed tomography (micro-CT) to accurately evaluate bone formation within 3D printed, porous Ti6Al4V implants manufactured using Electron Beam Melting (EBM), retrieved after six months of healing in sheep femur and tibia. All samples were scanned twice (i.e., before and after resin embedding), using fast, low-resolution scans (Skyscan 1172; Bruker micro-CT, Kontich, Belgium), and were analysed by 2D and 3D morphometry. The main questions posed were: (i) Can low resolution, fast scans provide morphometric data of bone formed inside (and around) metal implants with a complex, open-pore architecture?, (ii) Can micro-CT be used to accurately quantify both the bone area (BA) and bone-implant contact (BIC)?, (iii) What degree of error is introduced in the quantitative data by varying the threshold values?, and (iv) Does resin embedding influence the accuracy of the analysis? To validate the accuracy of micro-CT measurements, each data set was correlated with a corresponding centrally cut histological section...
November 21, 2016: Micron: the International Research and Review Journal for Microscopy
K C Nune, A Kumar, R D K Misra, S J Li, Y L Hao, R Yang
We elucidate here the osteoblasts functions and cellular activity in 3D printed interconnected porous architecture of functionally gradient Ti-6Al-4V alloy mesh structures in terms of cell proliferation and growth, distribution of cell nuclei, synthesis of proteins (actin, vinculin, and fibronectin), and calcium deposition. Cell culture studies with pre-osteoblasts indicated that the interconnected porous architecture of functionally gradient mesh arrays was conducive to osteoblast functions. However, there were statistically significant differences in the cellular response depending on the pore size in the functionally gradient structure...
February 1, 2017: Colloids and Surfaces. B, Biointerfaces
K C Nune, R D K Misra, S J Li, Y L Hao, R Yang
Titanium alloys (Ti-6Al-4V and Ti-6Al-7Nb) are widely used for implants, which are characterized by high elastic modulus (∼110 GPa) with (α + β) structure and that may induce undesirable stress shielding effect and immune responses associated with the presence of toxic elements. In this regard, we have combined the attributes of a new alloy design and the concept of additive manufacturing to fabricate 3D scaffolds with an interconnected porous structure. The new alloy is a β-type Ti-24Nb-4Zr-8Sn (Ti2448) alloy with significantly reduced modulus...
March 2017: Journal of Biomedical Materials Research. Part A
M Kuhn, M Renzler, J Postler, S Ralser, S Spieler, M Simpson, H Linnartz, A G G M Tielens, J Cami, A Mauracher, Y Wang, M Alcamí, F Martín, M K Beyer, R Wester, A Lindinger, P Scheier
Helium has a unique phase diagram and below 25 bar it does not form a solid even at the lowest temperatures. Electrostriction leads to the formation of a solid layer of helium around charged impurities at much lower pressures in liquid and superfluid helium. These so-called 'Atkins snowballs' have been investigated for several simple ions. Here we form HenC60(+) complexes with n exceeding 100 via electron ionization of helium nanodroplets doped with C60. Photofragmentation of these complexes is measured by merging a tunable narrow-bandwidth laser beam with the ions...
November 22, 2016: Nature Communications
H Wang, B J Zhao, R Z Yan, C Wang, C C Luo, M Hu
Objective: To investigate the biocompatibility of Ti-6Al-4V scaffolds fabricated by electron beam melting(EBM). Methods: Bone marrow mesenchymal stem cells(BMSC) co-cultured with Ti-6Al-4V specimens fabricated with EBM was prepared as experimental group and the regular cells culture was employed as control. The biocompatibility was detected using CCK-8 and cytoskeleton staining. The osteogenic differentiation ability was assessed using mineralization nodule formation. A 24 mm defect was created on the right mandibular body in 12 beagles...
November 9, 2016: Zhonghua Kou Qiang Yi Xue za Zhi, Zhonghua Kouqiang Yixue Zazhi, Chinese Journal of Stomatology
R Z Yan, Y F Li, C Wang, R X Li, Z W Liu, M Hu
Objective: To examine the biomechanical properties of three-dimensional(3D) printed electron beam melting(EBM) Ti-6Al-4V mesh as scaffold for mandibular repairment. Methods: We fabricated Ti-6Al-4V samples of different structures with strut, sheet and 3D mesh scaffolds(a controllable diameter 0.35, 0.50, 0.70 mm, distribution density: intensive sparse) by EBM process. The mechanical properties of these structures were examined by X-ray energy dispersive spectrum(EDS), uniaxial tensile test, three-point bending test, under compression load and compared with their different microstructure and mechanical properties...
November 9, 2016: Zhonghua Kou Qiang Yi Xue za Zhi, Zhonghua Kouqiang Yixue Zazhi, Chinese Journal of Stomatology
Hao Liu, Wei Li, Can Liu, Jie Tan, Hong Wang, Bao Hai, Hong Cai, Hui-Jie Leng, Zhong-Jun Liu, Chun-Li Song
Three-dimensional porous titanium alloys printed via electron beam melting have low stiffness similar to that of cortical bone and are promising scaffolds for orthopedic applications. However, the bio-inert nature of titanium alloy is poorly compatible with bone ingrowth. We previously observed that simvastatin/poloxamer 407 thermosensitive hydrogel induces endogenous angiogenic/osteogenic growth factors and promotes angiogenesis and osteogenesis, but the mechanical properties of this hydrogel are poor. The purpose of this study was to construct 3D-printed porous titanium scaffolds (pTi scaffolds) filled with simvastatin/hydrogel and evaluate the effects of this composite on osseointegration, bone ingrowth and neovascularization using a tibial defect rabbit model...
October 27, 2016: Biofabrication
Dmitry Serebrennikov, Evgeny Clementyev, Alexander Semenov, Anatoly Snigirev
A quantitative analysis of the crucial characteristics of currently used and promising materials for X-ray refractive optics is performed in the extended energy range 8-100 keV. According to the examined parameters, beryllium is the material of choice for X-ray compound refractive lenses (CRLs) in the energy range 8-25 keV. At higher energies the use of CRLs made of diamond and the cubic phase of boron nitride (c-BN) is beneficial. It was demonstrated that the presence of the elements of the fourth (or higher) period has a fatal effect on the functional X-ray properties even if low-Z elements dominate in the compound, like in YB66...
November 1, 2016: Journal of Synchrotron Radiation
Bingjing Zhao, Hong Wang, Ning Qiao, Chao Wang, Min Hu
The purpose of this study is to determine the corrosion resistance of Ti-6Al-4V alloy fabricated with electron beam melting and selective laser melting for implantation in vivo. Ti-6Al-4V alloy specimens were fabricated with electron beam melting (EBM) and selective laser melting (SLM). A wrought form of Ti-6Al-4V alloy was used as a control. Surface morphology observation, component analysis, corrosion resistance experimental results, electrochemical impedance spectroscopy, crevice corrosion resistance experimental results, immersion test and metal ions precipitation analysis were processed, respectively...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Guoyuan Li, Lei Wang, Wei Pan, Fei Yang, Wenbo Jiang, Xianbo Wu, Xiangdong Kong, Kerong Dai, Yongqiang Hao
Metallic implants with a low effective modulus can provide early load-bearing and reduce stress shielding, which is favorable for increasing in vivo life-span. In this research, porous Ti6Al4V scaffolds with three pore sizes (300~400, 400~500, and 500~700 μm) were manufactured by Electron Beam Melting, with an elastic modulus range of 3.7 to 1.7 GPa. Cytocompatibility in vitro and osseointegration ability in vivo of scaffolds were assessed. hBMSCs numbers increased on all porous scaffolds over time. The group with intended pore sizes of 300 to 400 μm was significantly higher than that of the other two porous scaffolds at days 5 and 7...
September 26, 2016: Scientific Reports
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