A BUSINESS CASE STUDY FOR COMPARING THE MANUFACTURING OF IMPLANT-SUPPORTED DENTURE FRAMES THROUGH DIRECT METAL LASER SINTERING TO CONVENTIONAL CASTING AND MACHINING PROCESSES

Conference ProceedingsRetaining dentures in edentulous patients is a common problem which can be overcome through the use of implant-supported denture frames. These frames are conventionally manufactured through the lost wax investment casting processes or through computer aided machining in cobalt chrome. Although Additive Manufacturing (AM) processes are now commonly used in the manufacturing of crowns and bridges in dentistry, the manufacturing of implant-supported denture frames is less common. This study aimed to investigate the feasibility of manufacturing these frames through AM from a business point of view compared to conventional casting and machining. A case study is presented where a full overdenture frame is designed and manufactured in Titanium-6Aluminium-4Vanadium (Ti-6Al-4V) alloy through the Direct Metal Laser Sintering (DMLS) process. This is compared to manufacturing the same frame in cobalt chrome through traditional processes in terms of manufacturing time and cost. Results from the study showed that it is more expensive and takes longer to produce overdenture frames through DMLS compared to conventional manufacturing techniques. Although costs and time can be reduced by producing a number of frames simultaneously on the DMLS machine’s building platform, the manufacturing process is still not considered viable for overdenture frames from a business point of view

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Somatotropin physiology - a review

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Protein digestion in ruminants

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Improvement of Surface Finish for Additive Manufactured Parts - A Comparison Study of Six Post Processing Techniques

The surface finish of additively manufactured parts is often poor mainly due to the “stair-stepping” effect of the manufacturing process which is mostly influenced by the layer thickness, build orientation and the inclination angle of the surface on the part. For form, fit or functional purposes, the surface finish of additive manufactured parts must often be enhanced. The aim of this research is to compare the surface finish of additively manufactured polymeric parts when post-processing techniques are applied. The test pieces were additively manufactured in nylon polyamide 12 (PA12), Alumide® and Acrylonitrile Butadiene Styrene (ABS) materials. The Laser Sintering (LS) process was used to manufacture the nylon and Alumide® test pieces while Material Extrusion (MEX) was used for the ABS test pieces. Six post processing techniques, namely tumbling, shot peening, Computer Numerical Control (CNC) machining, spray-painting, undercoat and hand finishing and chemical dissolving of surface of the test pieces were applied to the test pieces. Despite being the most time-consuming technique and producing poor consistency in dimensional accuracy, the hand finishing method resulted in the lowest surface roughness with improvements of up to 97.6%, 96% and 98.3% for nylon, Alumide® and ABS test pieces, respectively compared to the originally manufactured parts. Although CNC machining has the potential to improve the surface finish of a single face, the technique was found to be not efficient for improvement of surface roughness of a complex part with various inclination angles.Central University of Technology, Free State (CUT); De Montfort University (UK); Brunel University London; South African Research Chairs Initiative of the Department of Science and Technology; National Research Foundation of South Africa (Grant №97994); Collaborative Program in Additive Manufacturin

The effects of different dietary energy and protein levels on the digestive anatomy of ostriches.

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The use of energy by the splanchnic tissues and their metabolism of VFA, glucose and FFA in sheep fed high- and low-fibre diets*

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The plasma composition of karakul lambs fed isocaloric high-and low-fibre diets

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The ideal protein digestibility values of diets for ostriches determined with ileum-rectum anastomosis ostriches.

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