For isothermal crystallization, the development of relative crystallinity with the crystallization time is analyzed by the Avrami equation with the exponent
n = 2.7. The relatively high content this website of secondary crystallization at higher crystallization temperature can be obtained due to the high mobility of UHMWPE chains. For nonisothermal crystallization studies, the Avrami theory modified by Jeziorny is used, and the result is found that the Avrami exponent n is variable around 5 and decreases slightly as the cooling rate decreases. In addition, the extent of secondary crystallization increases with increasing cooling rate. The calculated activation energies are 881 kJ/mol for isothermal crystallization obtained from the Arrhenius equation and 462 kJ/mol for nonisothermal crystallization from the Kissinger equation, respectively. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 2442-2448, 2011″
“Study Design. A retrospective study
Objective. To classify the types and identify related factors on sagittal decompensation after corrective osteotomy selleck compound for lumbar degenerative kyphosis (LDK).
Summary of Background Data. There has been a skeptical view of surgical treatment of LDK owing to loss of sagittal balance
even after correction of kyphosis. However, there had been no report on the classification and risk factors of sagittal decompensation.
Methods. A total of 23 LDK patients who had undergone corrective osteotomy were enrolled. The mean follow-up period was 45.7 months. Radiographic parameters including sagittal balance, the cross-sectional area of paravertebral muscles, were analyzed. We classified the type of sagittal decompensation into thoracic (Group T) and lumbar decompensation selleck chemicals llc (Group L) with a reference line from the posterosuperior corner of the sacrum to the center of the T12-L1 disc. The type of sagittal decompensation was defined with the location of T1 and the reference line at the last follow-up radiographs.
Results. The mean number of fusion
segments was 7.7. Sagittal balance improved from 26.4 cm to 4 cm immediately after operation but deteriorated to 11.2 cm at the last follow-up. The decompensation was greater in Group T (11 cases) than in Group L (12 cases) (9.1 cm vs. 5.2 cm, P = 0.03). The comparative analysis showed significant differences between groups T and L in thoracic kyphosis at the last follow-up (Group T:L = 40.5 degrees:27.5 degrees, P = 0.04), preoperative thoracic kyphotic angle (Group T:L = 19.6 degrees:-1 degrees, P = 0.01), mean ratio of cross-sectional area of paravertebral muscles to intervertebral disc in T12-L1, and incidence of the preoperative compensatory thoracic lordosis (Group T:L = 27.3%: 100%, P = 0).
Conclusion. The mean sagittal decompensation after corrective osteotomy for LDK was 38.3%.