898 resultados para Gold (198Au) foils
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Welsch (Projektbearbeiter): Spottgedicht auf die republikanischen Agitatoren und ihre Anhänger
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BACKGROUND Implant-overdentures supported by rigid bars provide stability in the edentulous atrophic mandible. However, fractures of solder joints and matrices, and loosening of screws and matrices were observed with soldered gold bars (G-bars). Computer-aided designed/computer-assisted manufactured (CAD/CAM) titanium bars (Ti-bars) may reduce technical complications due to enhanced material quality. PURPOSE To compare prosthetic-technical maintenance service of mandibular implant-overdentures supported by CAD/CAM Ti-bar and soldered G-bar. MATERIALS AND METHODS Edentulous patients were consecutively admitted for implant-prosthodontic treatment with a maxillary complete denture and a mandibular implant-overdenture connected to a rigid G-bar or Ti-bar. Maintenance service and problems with the implant-retention device complex and the prosthesis were recorded during minimally 3-4 years. Annual peri-implant crestal bone level changes (ΔBIC) were radiographically assessed. RESULTS Data of 213 edentulous patients (mean age 68 ± 10 years), who had received a total of 477 tapered implants, were available. Ti-bar and G-bar comprised 101 and 112 patients with 231 and 246 implants, respectively. Ti-bar mostly exhibited distal bar extensions (96%) compared to 34% of G-bar (p < .001). Fracture rate of bars extensions (4.7% vs 14.8%, p < .001) and matrices (1% vs 13%, p < .001) was lower for Ti-bar. Matrices activation was required 2.4× less often in Ti-bar. ΔBIC remained stable for both groups. CONCLUSIONS Implant overdentures supported by soldered gold bars or milled CAD/CAM Ti-bars are a successful treatment modality but require regular maintenance service. These short-term observations support the hypothesis that CAD/CAM Ti-bars reduce technical complications. Fracture location indicated that the titanium thickness around the screw-access hole should be increased.
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Shalom Ben-Chorin
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The deformation behavior of atomically clean, nanometer sized tungsten / gold contacts was studied at room temperature in ultra-high vacuum. An instrument that combines atomic force microscopy (AFM), scanning tunneling microscopy (STM), and field ion microscopy (FIM) into a single experimental apparatus was designed, constructed, and calibrated. A cross-hair force sensor having a spring constant of - 442 N/m was developed and its motion was monitored during indentation experiments with a differential interferometer. Tungsten tips of controlled size (12.8 nm < tip radius < 2 1.6 nm) were first shaped and characterized using FIM and then indented into a Au (1 10) single crystal to depths ranging from 1.5 nrn to 18 nm using the force sensor. Continuum mechanics models were found to be valid in predicting elastic deformation during initial contact and plastic zone depths despite our small size regime. Multiple discrete yielding events lasting < 1.5 ms were observed during the plastic deformation regime; at the yield points a maximum value for the principal shear stress was measured to be 5 + 1 GPa. During tip withdrawal, "pop-out" events relating to material relaxation within the contact were observed. Adhesion between the tip and sample led to experimental signatures that suggest neck formation prior to the break of contact. STM images of indentation holes revealed various shapes that can be attributed to the (1 1 1 ) (1 10) crystallographic slip system in gold. FIM images of the tip after indentation showed no evidence of tip damage
Did Impending War in Europe Help Destroy the Gold Bloc in 1936? An Internal Inconsistency Hypothesis
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This paper investigates the gold bloc operated between France, the Netherlands, Switzerland and Belgium, especially over the period after the USA left the gold standard in March 1933 to its end in September 1936. It enquires into the effect of military-political developments in Germany and Italy on the sustainability of the gold bloc between its members. Juxtaposed is the view of leading political scientists, such as Henry Kissinger, who see impending war in Europe as deeply and adversely affecting psychology in Europe, and what may be called the standard "economists' view" that sees the demise of the gold bloc as being caused almost exclusively by economic factors. Developing concepts of external and internal inconsistency of the gold bloc, this investigation concludes that both economic and military-political developments played important roles in destroying the last vestiges of the gold standard.
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Vom Professor Dr. Karl Koch
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Vom Professor Dr. Karl Koch
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Von Dr. M. von Brunn
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Von W. Jagodzinski
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Signatur des Originals: S 36/F06647
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Signatur des Originals: S 36/F10732
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Signatur des Originals: S 36/F10733
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Vorbesitzer: P. Henckel