Search results

Sort By:

Limit search:

Shear Bond Strength Comparison between Conventional Dental Nano Zirconia Combinations and New Functionally Graded Nano Zirconia Combinations after Thermal-Mechanical Cycling

100%

Sun T., Lai R., Liu R., Shao L.

Acta Physica Polonica A

2014

vol. 125

issue 2

238-240

The aim of the study was to evaluate the core-veneer bond strength of graded zirconia combinations and compared those to conventional zirconia combinations after thermal and mechanical tests. Conventional zirconia-veneer combinations and graded zirconia-veneer combinations were made into cylinders. Prior to shear bond testing, half of each group was subjected to thermal and mechanical cycling testing at three conditional levels. All specimens were thereafter subjected to a shear force. The fractured surfaces were visually analyzed with scanning electron microscopy. The shear bond strength values of functionally graded zirconia combinations were significantly higher than zirconia combinations, irrespective of the fatigue conditions (P < 0.05). The shear bond strength values of graded zirconia combinations and zirconia combinations before thermal-mechanical cycling were higher than after (P < 0.05). The shear bond strength values of graded zirconia combinations was 40.99 ± 2.22 MPa, 39.44 ± 2.36 MPa, 37.45 ± 2.06 MPa, and 36.87 ± 2.18 MPa for conditions 0 to 3, respectively. The shear bond strength values were 26.75 ± 2.16 MPa, 23.95 ± 2.16 MPa, 21.65 ± 2.14 MPa, and 20.49 ± 2.16 MPa for zirconia combinations from conditions 0 to 3, respectively. The functionally graded zirconia combinations exhibited greater shear bond strength than zirconia combinations, irrespective of the fatigue conditions. Thermal-mechanical cycling had an impact on the shear bond strength of both graded zirconia combinations and conventional zirconia combinations.

XANES Study of La_{0.75-x}Gd_xCa_{0.25}MnO_{3-δ} Solid Solutions

88%

Drozd V., Pęka̶a M., Liu R., Lee J., Chen J.

Acta Physica Polonica A

2006

vol. 109

issue 4-5

583-589

A series of solid solutions La_{0. 75-x}Gd_xCa_{0.25}MnO_{3-δ} with 0.0≤x≤0.75 was prepared via carbonate precursor precipitation method. Final sintering was performed at 1250ºC in oxygen flow atmosphere. The samples obtained were characterized by scanning electron microscope, X-ray diffraction measurements. Oxygen stoichiometry was analyzed by iodometric titration method. X-ray absorption spectroscopic methods of Mn L-edge and Mn K-edge X-ray absorption near edge structure were used to study oxidation state of manganese in the solid solutions and elucidate features of their local crystal structure. Orthorhombic crystal structure characteristics of the solid solutions were refined by Rietveld method. An increase in oxygen deficiency and average manganese oxidation state were found to accompany Gd concentration increase in La_{0.75-x}Gd_xCa_{0.25}MnO_{3-δ}. These results are consistent with Mn L-edge X-ray absorption near edge structure spectra, where a gradual change of Mn oxidation state with Gd concentration increase was detected. Origins of oxygen deficiency La_{0.75- x}Gd_xCa_{0.25}MnO_{3-δ} are discussed in terms of structural disorder caused by Gd substitution for La.

Refine search results

2 Acta Physica Polonica A

1 2014

1 2006

2 Liu R.

1 Chen J.

1 Drozd V.

1 Lai R.

1 Lee J.

1 Pęka̶a M.

1 Shao L.

1 Sun T.

Search results

Shear Bond Strength Comparison between Conventional Dental Nano Zirconia Combinations and New Functionally Graded Nano Zirconia Combinations after Thermal-Mechanical Cycling

XANES Study of La_{0.75-x}Gd_xCa_{0.25}MnO_{3-δ} Solid Solutions