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Int J Numer Method Biomed Eng ; 28(11): 1156-64, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23109384


The finite element method with linear elastic assumption for predicting the intraocular pressure (IOP) readings after reshaping of the corneal structure is demonstrated in the present study. Twelve effective eye measurements in seven subjects were examined using the TOPCON LX-10, a noncontact intraocular pressure measurement technique, before and after laser-assisted in situ Keratomileusis surgery. A linear elastic model was introduced to reduce possible errors from a complicated anisotropic model with uncertain tissue parameters. Linear relationship between the simplified removal depth of laser-assisted in situ Keratomileusis and predicted IOP was expected, and the comparisons between measurements and the predicted model were made. The results indicated that the expected IOP readings are close to the measurement IOP values, while larger errors occur at smaller IOP conditions. In conclusion, the linear elastic finite element approach can already reveal parameters that influence measurement data the most, and the interaction between parameters was higher than we had expected. This helps us to build the confidence on implementing the anisotropic model.

Pressão Intraocular/fisiologia , Ceratomileuse Assistida por Excimer Laser In Situ , Modelos Biológicos , Tonometria Ocular/métodos , Algoritmos , Anisotropia , Engenharia Biomédica , Simulação por Computador , Córnea/anatomia & histologia , Córnea/fisiologia , Córnea/cirurgia , Elasticidade , Análise de Elementos Finitos , Ceratomileuse Assistida por Excimer Laser In Situ/efeitos adversos , Modelos Lineares , Tonometria Ocular/estatística & dados numéricos
Nanoscale Res Lett ; 7(1): 372, 2012 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-22768847


One-dimensional pure zinc oxide (ZnO) and Y-doped ZnO nanorod arrays have been successfully fabricated on the silicon substrate for comparison by a simple hydrothermal process at the low temperature of 90°C. The Y-doped nanorods exhibit the same c-axis-oriented wurtzite hexagonal structure as pure ZnO nanorods. Based on the results of photoluminescence, an enhancement of defect-induced green-yellow visible emission is observed for the Y-doped ZnO nanorods. The decrease of E2(H) mode intensity and increase of E1(LO) mode intensity examined by the Raman spectrum also indicate the increase of defects for the Y-doped ZnO nanorods. As compared to pure ZnO nanorods, Y-doped ZnO nanorods show a remarked increase of saturation magnetization. The combination of visible photoluminescence and ferromagnetism measurement results indicates the increase of oxygen defects due to the Y doping which plays a crucial role in the optical and magnetic performances of the ZnO nanorods.

J Opt Soc Am A Opt Image Sci Vis ; 29(7): 1427-35, 2012 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-22751411


A Fresnel-like structure is required for various kinds of applications, such as contact lenses in the biomedical field, solar concentrators in the energy industry, wave-front correctors for display technology, and beam shaping for illumination systems. In this report, the author provides a simple iterative algorithm that can generate prism structures on arbitrary curved surfaces in an analytical form. Using this algorithm, a spreadsheet program can easily generate the profile of prism structures for optical software simulation. Moreover, a noniterative formulation is derived in order to reduce the design procedures. Comparisons between iterative and noniterative formulations prove the feasibility and robustness of the present approach.