Machinable glass-ceramics forming as a restorative dental material.
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MgO, SiO(2), Al(2)O(3), MgF(2), CaF(2), CaCO(3), SrCO(3), and P(2)O(5) were used to prepare glass-ceramics for restorative dental materials. Thermal properties, phases, microstructures and hardness were characterized by DTA, XRD, SEM and Vickers microhardness. Three-point bending strength and fracture toughness were applied by UTM according to ISO 6872: 1997(E). XRD showed that the glass crystallized at 892 degrees C (second crystallization temperature+20 degrees C) for 3 hrs consisted mainly of calcium-mica and fluorapatite crystalline phases. Average hardness (3.70 GPa) closely matched human enamel (3.20 GPa). The higher fracture toughness (2.04 MPa radicalm) combined with the hardness to give a lower brittleness index (1.81 microm(-1/2)) which indicates that they have exceptional machinability. Bending strength results (176.61 MPa) were analyzed by Weibull analysis to determine modulus value (m=17.80). Machinability of the calcium mica-fluorapatite glass-ceramic was demonstrated by fabricating with CAD/CAM. (+info)
Investigation into stability of poly(vinyl alcohol)-based Opadry(R) II films.
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Soda-lime glass as a binder in reusable experimental investment for dental castings.
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In this study, different glasses were investigated to improve reusable investments. Borosilicate glass (BSG) powder and soda-lime glass (SLG) powder were prepared by milling broken beakers and microscope slides, respectively, and used in experimental investments (I-BSG, I-SLG) by blending glass powder (10 wt%) with cristobalite (90 wt%). Some properties and casting fits were evaluated with commercial gypsum-bonded investment as the control. Both BSG and SLG were mainly composed of Si, but SLG had a large Ca content. The glass transition temperatures were approximately 800 degrees C (BSG) and 700 degrees C (SLG). Experimental investments with heating showed the significantly (p<0.05) higher expansion than that of the control. The compressive strength of I-SLG was higher than that of I-BSG, and increased with temperature. The MOD inlay obtained from I-SLG had a significantly smaller gap than that from I-BSG, and was comparable to the control. These results suggest SLG could be applied clinically as a reusable dental investment. (+info)
Synthesis of nanocrystalline SnO(x) (x = 1-2) thin film using a chemical bath deposition method with improved deposition time, temperature and pH.
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Thermal stability of the prototypical Mn porphyrin-based superoxide dismutase mimic and potent oxidative-stress redox modulator Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin chloride, MnTE-2-PyP(5+).
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Mechanically induced amorphization of drugs: a study of the thermal behavior of cryomilled compounds.
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Regulation of the Plasmodium motor complex: phosphorylation of myosin A tail-interacting protein (MTIP) loosens its grip on MyoA.
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Real-time protein unfolding: a method for determining the kinetics of native protein denaturation using a quantitative real-time thermocycler.
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