ABSTRACT
The existing studies indicate polymers will present obviously different properties in tension and compression (bimodular effect) which is generally ignored because of the complexity of the analysis. In this study, a functionally graded piezoelectric cantilever beam with bimodular effect was investigated via analytical and numerical methods, respectively, in which a one-dimensional theoretical solution was derived by neglecting some unimportant factors and a two-dimensional numerical simulation was performed based on the model of tension-compression subarea. A full comparison was made to show the rationality of one-dimensional theoretical solution and two-dimensional numerical simulation. The result indicates that the layered model of tension-compression subarea also makes it possible to use numerical technique to simulate the problem of functionally graded piezoelectric cantilever beam with bimodular effect. Besides, the modulus of elasticity E* and the bending stiffness D* proposed in the one-dimensional problem may succinctly describe the piezoelectric effect on the classical mechanical problem without electromechanical coupling, which shows the advantages of one-dimensional solution in engineering applications, especially in the analysis and design of energy harvesting/sensing/actuating devices made of piezoelectric polymers whose bimodular effect is relatively obvious.
ABSTRACT
<p><b>OBJECTIVE</b>To analyze the common outer membrane proteins (OMP) from Porphyromonas gingivalis (Pg) by surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) and to provide antigens for the subsequent experiments in screening vaccine for periodontitis therapy.</p><p><b>METHODS</b>Four strains of Pg were cultured under anaerobic conditions. The common OMP was extracted through ultracentrifugation and SELDI-TOF-MS was employed to detect the expressions of proteomes by chip H(50). The data was analyzed by Biomarker Wizard.</p><p><b>RESULTS</b>Four kinds of strains of OMP fingerprint spectrum were obtained. Seventy-one proteins of PgATCC33277, 74 proteins of PgW83, 76 proteins of PgW301 and 72 proteins of Pg381 were captured by chip H(50). Thirteen common proteins were identified according to fingerprint spectrum. There was only 1 of the 13 common proteins identified in NCBI protein bank.</p><p><b>CONCLUSIONS</b>SELDI-TOF-MS has good reproducibility and high sensibility and can be used to identify the common OMP of Pg. The 13 proteins have a potential value in the screening vaccine candidate antigen sites for periodontitis.</p>
