ABSTRACT
Abstract The aim of the study was to evaluate the effect of the incorporation of different fillers on an experimental vinyl polysiloxane (VPS) at two different concentrations, 20% and 40%. Different fillers were added to an experimental VPS. The study was developed in two stages: (i) incorporation of fillers in different concentrations: (a) 20 wt% fillers, and (b) 40 wt%. The fillers were added to experimental VPS and mixed with a speed mixer; (ii) characterization of experimental VPS; after the base paste and catalyst paste were mixed, the experimental VPS was used to make specimens specifically for each test, which were stored at 23°C for 24 hours. The tests were designed according to the specific standardization for the analysis of tensile strength, detail reproduction, Shore A hardness, and elastic recovery. For analysis of filler size pattern, scanning electron microscopy at 1500× magnification was used. The aerosil OX-50 40% (AE), and pure aluminum hydroxide 40% (PAH) groups presented the highest tensile strength and Shore A hardness values. However, those were the only groups that did not present continuous detail reproduction of an intersection of 20 μm line. The elastic recovery was not statistically significant. The undesirable characteristics of VPS (lowest Shore A hardness and tensile strength) were observed when it was added to the composition of acrylic polymer (AP) and fiberglass (FG) in both concentrations, 20% and 40%. In groups AE and PAH, agglomerates of nanofillers were shown in SEM micrography, while the other groups presented different shapes and fillers sizes.
Subject(s)
Polyvinyls/chemistry , Siloxanes/chemistry , Dental Impression Materials/chemistry , Particle Size , Reference Values , Surface Properties , Tensile Strength , Time Factors , Materials Testing , Microscopy, Electron, Scanning , Reproducibility of Results , Analysis of Variance , Elasticity , Hardness TestsABSTRACT
The same physics applies to the largest scale, Universe, as well as to the smallest scale, Elementary Particles
Subject(s)
Elementary Particles , PhysicsABSTRACT
ABSTRACT The influence of the nuclear medium on lepto-production of hadrons was studied in semi-inclusive deep-inelastic scattering off several nuclear targets. In particular, at the HERMES experiment at DESY, the differential multiplicity for krypton relative to that of deuterium has been measured for the first time for various identified hadrons (p+, p-, p0, K+, K-, p and anti-p) as a function of the virtual photon energy n, the fraction z of this energy transferred to the hadron, and the hadron transverse momentum squared pt2. The distribution of the hadron transverse momentum is broadened towards high pt2 in the nuclear medium, in a manner resembling the Cronin effect previously observed in collisions of heavy ions and protons with nuclei. Moreover, by studying the hadron attenuation of the leading and sub-leading hadrons, it will be shown, for the first time, an additional tool for studying modifications of hadronization in nuclear matter.
La influencia del medio nuclear en la lepto-producción de hadrones se estudió en la dispersión semi-inclusiva profundamente inelástica de varios blancos nucleares. En particular, en el experimento HERMES en DESY, la multiplicidad diferencial del kriptón en relación con la del deuterio se midió por primera vez para varios hadrones identificados (p+, p-, p0, K+, K-, p y anti-p) como una función de la energía fotónica virtual n, la fracción z de esta energía transferida al hadrón y el cuadrado del momento transversal del hadrón pt2. La distribución del momento transversal del hadrón se ensancha hacia los pt2 altos en el medio nuclear, de manera que semeja el efecto Cronin anteriormente observado en las colisiones de protones e iones pesados con los núcleos. Además, al estudiar la atenuación de los hadrones principales y sub-principales se mostrará por primera vez una herramienta adicional para el estudio de las modificaciones de la hadronización en materia nuclear.