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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of prosthodontics 2 (1993), S. 0 
    ISSN: 1532-849X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Purpose This investigation compared the mechanical properties of three base metal casting alloys (Vitallium2, Neoloy N [Regular], and Regalloy T) for removable partial denture (RPD) frameworks with those for two base metal RPD alloys (Vitallium, Jelenko LG) whose mechanical properties had been previously reported.Materials and Methods Plastic patterns with dimensions meeting ADA specification no. 14 requirements were used with appropriate casting investments to cast tensile test bars of the five alloys. Nine specimens of each alloy were loaded to failure, and the mechanical properties of modulus of elasticity, 0.1% yield strength, 0.2% yield strength, and tensile strength were obtained from five well-behaved load-elongation plots. Values of percentage elongation were also determined, along with Vickers hardness of the work-hardened alloys from polished cross-sections of fractured tensile specimens. The fracture surfaces for representative specimens of each alloy were examined with a scanning electron microscope.Results Although the measured values of mechanical properties generally agreed with those reported by the manufacturers, differences found for Vitallium and Jelenko LG with previous investigations suggest that there may have been some changes in alloy compositions and processing by the manufacturers. The investment burnout procedure adopted for the plastic patterns and the present casting conditions may also have affected the mechanical properties of some alloys. Two alloys, Jelenko LG and Regalloy T, had mean values of percentage elongation exceeding 10%, but caution is recommended for clinicians and dental laboratories when performing clasp adjustments with all five alloys because of the substantial work hardening that can occur.Conclusions In general, all of the alloys met the requirements in ADA specification no. 14 for base metal RPD alloys. Further research will be necessary to determine the relationships between the mechanical properties, particularly yield strength, rate of work hardening and percentage elongation, and the clinical requirements for these alloys.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Potassium-limited cultures of Candida utilis grown with ammonium chloride as the sole nitrogen source attained a higher dry weight than similar cultures grown with sodium nitrate as the sole nitrogen source. This increase depended on the extracellular ammonia concentration and was not due to accumulation of storage polymers. We conclude that in this yeast ammonium ions can fulfill to some extent the physiological role of potassium ions and that the intracellular concentration of ammonium ions is predominantly determined by the ammonia concentration in the culture medium.
    Type of Medium: Electronic Resource
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  • 3
    facet.materialart.
    Unknown
    London : Periodicals Archive Online (PAO)
    Survival. 31:2 (1989:Mar./Apr.) 157 
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Advances in Polymer Technology 12 (1993), S. 353-360 
    ISSN: 0730-6679
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Research in understanding the mechanisms behind driving forces in the fully filled nonintermeshing twin screw extruder concentrated on experimental analysis of the relation between stagger, screw speed, and cross-channel flow due to measured pressure differential in the nip region. A new measure of the pressure driving force was also sought out, to correlate new data to previous findings from visual studies. The first part of the study was to obtain the values for the dynamic pressure on both sides of the nip region. Further refinements to the equipment used in previous studies allowed closer placement of the transducers in the nip region. After the data were stored, analysis started by determining the δp values from the trace of the pressure differential. By plotting these values, we obtain a highly repeatable curve confirming that the greatest pressure flow occurs at small staggers. A simple 2-D model for pressure flow in the nip region was used to estimate the effect of the cross-channel pressure differential. Values for the cross-channel pressure flow were calculated and compared with the drag flow and found to be significant. © 1993 by John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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