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https://www.readbyqxmd.com/read/29136309/comparison-of-fit-of-dentures-fabricated-by-traditional-techniques-versus-cad-cam-technology
#1
J Bryan McLaughlin, Van Ramos, Douglas P Dickinson
PURPOSE: To compare the shrinkage of denture bases fabricated by three methods: CAD/CAM, compression molding, and injection molding. The effect of arch form and palate depth was also tested. MATERIALS AND METHODS: Nine titanium casts, representing combinations of tapered, ovoid, and square arch forms and shallow, medium, and deep palate depths, were fabricated using electron beam melting (EBM) technology. For each base fabrication method, three poly(vinyl siloxane) impressions were made from each cast, 27 dentures for each method...
November 14, 2017: Journal of Prosthodontics: Official Journal of the American College of Prosthodontists
https://www.readbyqxmd.com/read/29134773/design-and-biological-functionality-of-a-novel-hybrid-ti-6al-4v-hydrogel-system-for-reconstruction-of-bone-defects
#2
Alok Kumar, K C Nune, R D K Misra
We have designed a unique injectable bioactive hydrogel comprising of alginate, gelatin, and nanocrystalline hydroxyapatite and loaded with osteoblasts, with the ability to infiltrate into three-dimensional Ti-6Al-4V scaffolds with interconnected porous architecture, fabricated by electron beam melting (EBM). A two-step crosslinking process using the EDC/NHS and CaCl2 was adopted and found to be effective in the fabrication of cell-loaded hydrogel/Ti-6Al-4V scaffold system. This hybrid Ti-6Al-4V scaffold/hydrogel system was designed for the reconstruction of bone defects, which are difficult to heal in the absence of suitable support materials...
November 14, 2017: Journal of Tissue Engineering and Regenerative Medicine
https://www.readbyqxmd.com/read/29111845/pre-clinical-evaluation-of-the-mechanical-properties-of-a-low-stiffness-cement-injectable-hip-stem
#3
Ibrahim Eldesouky, Ola Harrysson, Denis J Marcellin-Little, Harvey West, Hassan El-Hofy
In total hip arthroplasty (THA), the femoral stem can be fixed with or without bone cement. Cementless stem fixation is recommended for young and active patients as it eliminates the risk of loss of fixation at the bone-cement and cement-implant interfaces. Cementless fixation, however, suffers from a relatively high early revision rate. In the current research, a novel low-stiffness hip stem was designed, fabricated and tested. The stem design provided the option to inject biodegradable bone cement that could enhance initial stem stability...
November 7, 2017: Journal of Medical Engineering & Technology
https://www.readbyqxmd.com/read/29096063/halide-effects-on-the-sublimation-temperature-of-x-au-l-complexes-implications-for-their-use-as-precursors-in-vapor-phase-deposition-methods
#4
Will G Carden, Jakub Pedziwiatr, Khalil A Abboud, Lisa McElwee-White
Trends in volatility with changes in the halide ligand were established for gold(I) complexes of the type X-Au-L [X = Cl, Br, I; L = CN(t)Bu, CNMe, PMe3, P(NMe2)3, P(OCH2CF3)3] by determining the temperatures for the onset of sublimation (Tsub) at a fixed pressure. Within each series of isocyanide complexes, Tsub decreases with increasing atomic radius of the halide, making the iodide complex the most volatile. For the phosphine and phosphoramidate complexes, the chloride and bromide have similar Tsub values with the bromide slightly higher, but the iodide complex is again the most volatile of the three...
November 9, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29038806/kinetics-of-volatile-impurity-removal-from-silicon-by-electron-beam-melting-for-photovoltaic-applications
#5
Shuang Shi, Pengting Li, Jianxiong Meng, Dachuan Jiang, Yi Tan, H M Noor Ul Huda Khan Asghar
A full domain control model is established for impurity transportation in the liquid phase, gas-liquid interface and gas phase of silicon to analyze the dynamic mechanics of impurity removal. The results show that the overall mass transfer coefficient mainly depends on the temperature and the chamber pressure. Its value increases with the increase of temperature or the decrease of chamber pressure. Under the same melting condition, the order of the overall mass transfer coefficients for P, Al and Ca is kP > kAl > kCa, indicating that P is easier to remove by evaporation...
October 25, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28967051/additive-manufacturing-of-titanium-alloys-in-the-biomedical-field-processes-properties-and-applications
#6
Francesco Trevisan, Flaviana Calignano, Alberta Aversa, Giulio Marchese, Mariangela Lombardi, Sara Biamino, Daniele Ugues, Diego Manfredi
The mechanical properties and biocompatibility of titanium alloy medical devices and implants produced by additive manufacturing (AM) technologies - in particular, selective laser melting (SLM), electron beam melting (EBM) and laser metal deposition (LMD) - have been investigated by several researchers demonstrating how these innovative processes are able to fulfil medical requirements for clinical applications. This work reviews the advantages given by these technologies, which include the possibility to create porous complex structures to improve osseointegration and mechanical properties (best match with the modulus of elasticity of local bone), to lower processing costs, to produce custom-made implants according to the data for the patient acquired via computed tomography and to reduce waste...
September 25, 2017: Journal of Applied Biomaterials & Functional Materials
https://www.readbyqxmd.com/read/28937643/design-and-additive-manufacturing-of-3d-phononic-band-gap-structures-based-on-gradient-based-optimization
#7
Maximilian Wormser, Fabian Wein, Michael Stingl, Carolin Körner
We present a novel approach for gradient based maximization of phononic band gaps. The approach is a geometry projection method combining parametric shape optimization with density based topology optimization. By this approach, we obtain, in a two dimension setting, cellular structures exhibiting relative and normalized band gaps of more than 8 and 1.6, respectively. The controlling parameter is the minimal strut size, which also corresponds with the obtained stiffness of the structure. The resulting design principle is manually interpreted into a three dimensional structure from which cellular metal samples are fabricated by selective electron beam melting...
September 22, 2017: Materials
https://www.readbyqxmd.com/read/28937638/effects-of-processing-parameters-on-surface-roughness-of-additive-manufactured-ti-6al-4v-via-electron-beam-melting
#8
Pan Wang, Wai Jack Sin, Mui Ling Sharon Nai, Jun Wei
As one of the powder bed fusion additive manufacturing technologies, electron beam melting (EBM) is gaining more and more attention due to its near-net-shape production capacity with low residual stress and good mechanical properties. These characteristics also allow EBM built parts to be used as produced without post-processing. However, the as-built rough surface introduces a detrimental influence on the mechanical properties of metallic alloys. Thereafter, understanding the effects of processing parameters on the part's surface roughness, in turn, becomes critical...
September 22, 2017: Materials
https://www.readbyqxmd.com/read/28937633/predictive-simulation-of-process-windows-for-powder-bed-fusion-additive-manufacturing-influence-of-the-powder-bulk-density
#9
Alexander M Rausch, Vera E Küng, Christoph Pobel, Matthias Markl, Carolin Körner
The resulting properties of parts fabricated by powder bed fusion additive manufacturing processes are determined by their porosity, local composition, and microstructure. The objective of this work is to examine the influence of the stochastic powder bed on the process window for dense parts by means of numerical simulation. The investigations demonstrate the unique capability of simulating macroscopic domains in the range of millimeters with a mesoscopic approach, which resolves the powder bed and the hydrodynamics of the melt pool...
September 22, 2017: Materials
https://www.readbyqxmd.com/read/28933439/3d-printing-of-high-strength-aluminium-alloys
#10
John H Martin, Brennan D Yahata, Jacob M Hundley, Justin A Mayer, Tobias A Schaedler, Tresa M Pollock
Metal-based additive manufacturing, or three-dimensional (3D) printing, is a potentially disruptive technology across multiple industries, including the aerospace, biomedical and automotive industries. Building up metal components layer by layer increases design freedom and manufacturing flexibility, thereby enabling complex geometries, increased product customization and shorter time to market, while eliminating traditional economy-of-scale constraints. However, currently only a few alloys, the most relevant being AlSi10Mg, TiAl6V4, CoCr and Inconel 718, can be reliably printed; the vast majority of the more than 5,500 alloys in use today cannot be additively manufactured because the melting and solidification dynamics during the printing process lead to intolerable microstructures with large columnar grains and periodic cracks...
September 20, 2017: Nature
https://www.readbyqxmd.com/read/28886950/influence-of-thermo-mechanical-cycling-on-porcelain-bonding-to-cobalt-chromium-and-titanium-dental-alloys-fabricated-by-casting-milling-and-selective-laser-melting
#11
Maja Antanasova, Andraž Kocjan, Janez Kovač, Borut Žužek, Peter Jevnikar
PURPOSE: The aim has been to determine the effect of thermo-mechanical cycling on shear-bond-strength (SBS) of dental porcelain to Co-Cr and Ti-based alloys fabricated by casting, computer-numerical-controlled milling, and selective-laser-melting (SLM). METHODS: Seven groups (n=22/group) of metal cylinders were fabricated by casting (Co-Cr and commercially pure-cpTi), milling (Co-Cr, cpTi, Ti-6Al-4V) or by SLM (Co-Cr and Ti-6Al-4V) and abraded with airborne-particles...
September 5, 2017: Journal of Prosthodontic Research
https://www.readbyqxmd.com/read/28874795/tailoring-the-thermal-conductivity-of-the-powder-bed-in-electron-beam-melting-ebm-additive-manufacturing
#12
C J Smith, S Tammas-Williams, E Hernandez-Nava, I Todd
Metallic powder bed additive manufacturing is capable of producing complex, functional parts by repeatedly depositing thin layers of powder particles atop of each other whilst selectively melting the corresponding part cross-section into each layer. A weakness with this approach arises when melting overhanging features, which have no prior melted material directly beneath them. This is due to the lower thermal conductivity of the powder relative to solid material, which as a result leads to an accumulation of heat and thus distortion...
September 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28872620/electron-beam-welding-of-in792-ds-effects-of-pass-speed-and-pwht-on-microstructure-and-hardness
#13
Giuliano Angella, Giuseppe Barbieri, Riccardo Donnini, Roberto Montanari, Maria Richetta, Alessandra Varone
Electron Beam (EB) welding has been used to realize seams on 2 mm-thick plates of directionally solidified (DS) IN792 superalloy. The first part of this work evidenced the importance of pre-heating the workpiece to avoid the formation of long cracks in the seam. The comparison of different pre-heating temperatures (PHT) and pass speeds (v) allowed the identification of optimal process parameters, namely PHT = 300 °C and v = 2.5 m/min. The microstructural features of the melted zone (MZ); the heat affected zone (HAZ), and base material (BM) were investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), electron back-scattered diffraction (EBSD), X-ray diffraction (XRD), and micro-hardness tests...
September 5, 2017: Materials
https://www.readbyqxmd.com/read/28869368/3d-metal-printing-additive-manufacturing-technologies-for-frameworks-of-implant-borne-fixed-dental-prosthesis
#14
M R León, I M Klemm, J García-Arranz, M Özcan
An edentulous patient was rehabilitated with maxillary metal-ceramic and mandibular metal-resin implant-supported fixed dental prosthesis (FDP). Metal frameworks of the FDPs were fabricated using 3D additive manufacturing technologies utilizing selective laser melting (SLM) and electron beam melting (EBM) processes. Both SLM and EBM technologies were employed in combination with computer numerical control (CNC) post-machining at the implant interface. This report highlights the technical and clinical protocol for fabrication of FDPs using SLM and EBM additive technologies...
September 2017: European Journal of Prosthodontics and Restorative Dentistry
https://www.readbyqxmd.com/read/28819966/characterization-of-nanopipet-supported-ities-tips-for-scanning-electrochemical-microscopy-of-single-solid-state-nanopores
#15
Ran Chen, Ryan J Balla, Alex Lima, Shigeru Amemiya
Nanoscale scanning electrochemical microscopy (SECM) is a powerful scanning probe technique that enables high-resolution imaging of chemical processes at single nanometer-sized objects. However, it has been a challenging task to quantitatively understand nanoscale SECM images, which requires accurate characterization of the size and geometry of nanoelectrode tips. Herein, we address this challenge through transmission electron microscopy (TEM) of quartz nanopipets for SECM imaging of single solid-state nanopores by using nanopipet-supported interfaces between two immiscible electrolyte solutions (ITIES) as tips...
September 19, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28796180/formation-and-properties-of-laser-induced-periodic-surface-structures-on-different-glasses
#16
Stephan Gräf, Clemens Kunz, Frank A Müller
The formation and properties of laser-induced periodic surface structures (LIPSS) was investigated on different technically relevant glasses including fused silica, borosilicate glass, and soda-lime-silicate glass under irradiation of fs-laser pulses characterized by a pulse duration τ = 300 fs and a laser wavelength λ = 1025 nm. For this purpose, LIPSS were fabricated in an air environment at normal incidence with different laser peak fluence, pulse number, and repetition frequency. The generated structures were characterized by using optical microscopy, scanning electron microscopy, focused ion beam preparation and Fast-Fourier transformation...
August 10, 2017: Materials
https://www.readbyqxmd.com/read/28774095/an-investigation-of-sintering-parameters-on-titanium-powder-for-electron-beam-melting-processing-optimization
#17
Philipp Drescher, Mohamed Sarhan, Hermann Seitz
Selective electron beam melting (SEBM) is a relatively new additive manufacturing technology for metallic materials. Specific to this technology is the sintering of the metal powder prior to the melting process. The sintering process has disadvantages for post-processing. The post-processing of parts produced by SEBM typically involves the removal of semi-sintered powder through the use of a powder blasting system. Furthermore, the sintering of large areas before melting decreases productivity. Current investigations are aimed at improving the sintering process in order to achieve better productivity, geometric accuracy, and resolution...
December 1, 2016: Materials
https://www.readbyqxmd.com/read/28773031/additive-manufacturing-processes-selective-laser-melting-electron-beam-melting-and-binder-jetting-selection-guidelines
#18
REVIEW
Prashanth Konda Gokuldoss, Sri Kolla, Jürgen Eckert
Additive manufacturing (AM), also known as 3D printing or rapid prototyping, is gaining increasing attention due to its ability to produce parts with added functionality and increased complexities in geometrical design, on top of the fact that it is theoretically possible to produce any shape without limitations. However, most of the research on additive manufacturing techniques are focused on the development of materials/process parameters/products design with different additive manufacturing processes such as selective laser melting, electron beam melting, or binder jetting...
June 19, 2017: Materials
https://www.readbyqxmd.com/read/28772572/effect-of-energy-input-on-microstructure-and-mechanical-properties-of-titanium-aluminide-alloy-fabricated-by-the-additive-manufacturing-process-of-electron-beam-melting
#19
Ashfaq Mohammad, Abdulrahman M Alahmari, Muneer Khan Mohammed, Ravi Kottan Renganayagalu, Khaja Moiduddin
Titanium aluminides qualify adequately for advanced aero-engine applications in place of conventional nickel based superalloys. The combination of high temperature properties and lower density gives an edge to the titanium aluminide alloys. Nevertheless, challenges remain on how to process these essentially intermetallic alloys in to an actual product. Electron Beam Melting (EBM), an Additive Manufacturing Method, can build complex shaped solid parts from a given feedstock powder, thus overcoming the shortcomings of the conventional processing techniques such as machining and forging...
February 21, 2017: Materials
https://www.readbyqxmd.com/read/28752320/polymer-gel-dosimeters-with-pva-ga-matrix
#20
Seyed Mohammad Mahdi Abtahi, Hamid Sadeghi Abandansari
Properties of a new polymer gel with cross-linked polyvinyl alcohol as a gelatinous matrix were investigated. The new polymer gel dosimeter was named PVABAT. The irradiation was performed using a calibrated (60)Co beam. The dose responses of the PVABAT formulations were quantified with MRI transverse relaxation rate (R2) measurements. The results show that the PVABAT gel responds linearly to the absorbed dose for doses from 30 up to 45 Gy. The maximal amount of [Formula: see text] of PVABAT polymer gel dosimeter was about 0...
September 2017: Australasian Physical & Engineering Sciences in Medicine
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