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J M Sampaio

Publications and source records attributed to J M Sampaio.

8 recordsLinked to original sources
PubMed2003

Electron capture rates on nuclei and implications for stellar core collapse.

Supernova simulations to date have assumed that during core collapse electron captures occur dominantly on free protons, while captures on heavy nuclei are Pauli blocked and are ignored. We have calculated rates for electron capture on nuclei with mass numbers A=65-112 for the temperatures and densities appropriate for core collapse. We find that these rates are large enough so that, in contrast to previous assumptions, electron capture on nuclei dominates over capture on free protons. This leads to significant changes in core collapse simulations.

Journal Article↗
PubMedDate not supplied

[Study of some physical and biological properties of an endodontic sealer composed of calcium hydroxide].

The authors present a study of the physical and biological properties of a new endodontic cement known as Sealapex. In its composition the presence of calcium hydroxide is introduced in order to induce calcification of the periapical tissue. Our results using glass round cover slips implanted on the subcutaneous tissue of mice indicated a persistent foreign body reaction (60 days). The physical properties studied compared to N-Rickert ciment indicated, a decreased leakage. Adhesivity tests didn't give us significant values. Laboratorial studies and clinical trials are necessary to a complete acceptance of this new ciment in endodontic treatment.

Animals↗
PubMedDate not supplied

Quality analysis of the root canal filling employing gutta-percha thermoplasticized at a low temperature (Ultrafil system).

The objective of this study was the investigation of the sealing properties of gutta-percha thermoplasticized at a low temperature by either employing or not N-Rickert cement and vertical condensation. Methylene blue at 0.5% was used to demonstrate the apical leakage. Results demonstrated that minor penetration indexes were attained when cement was not employed and vertical condensation was accomplished.

Dental Cements↗