Objective To generate finite element models of human head based on segmented computer tomography data.Methods A four-step procedure was adopted to configure the coarse mesh.The method of longest edge propagation path and the edge collapse were used to refine and optimize the final mesh.The method was evaluated by means of computer simulations in a 3-concentric-sphere head model and a three-layer realistic geometry human head model.Results The present simulation results showed reliability and rationality of the finite element computation,thus indicate the suitability of the developed method.Conclusion A multi-tissue finite element model is obtained by using this method.It can be applied to the computation of finite element based bio-mechanics and bio-electromagnetism.

Objective To study the influence of white matter anisotropic conductivity on scalp electric potential distribution.Methods According to the volume constraint water diffusion tensor was converted to conductivity tensor,and the five-layer(white matter,grey matter,CSF,skull,scalp)finite element model(FEM)was constructed based on the DTI data.Based on this model first-order FEM algorithm was implemented.And the scalp electric potential distribution was calculated by using current dipole modal.Results Anisotropic conductivity of white matter has influence in EEG problem,and more influence when the ratio of radius and tangential of volume constraint is greater.The right-left dipoles have more influence than superior-inferior ones.Conclusion In the study of EEG,the anisotropic conductivity of brain tissue cannot be neglected.

Objective To develop a new Two-step magnetic resonance electrical impedance tomography(MREIT)algorithm based on radial basic function(RBF)neural network for imaging electrical impedance distribution of a head.Methods Firstly,the magnetic resonance imaging(MRI)system with high resolution was used to set up 3D model of the object and to identify the boundaries of different tissues.Then RBF MREIT algorithm was applied to estimate piece-wise homogeneous impedance values of those tissues,respectively.Furthermore,the impedance of each element within each region of the FEM model was estimated according to the RBF genetic algorithm method based on the piece-wise constant impedance.Results Computer simulations were conducted in a three-sphere head model(scalp-skull-brain,SSB)and the simulation results showed the applicability and feasibility of the present Two-step MREIT algorithm in imaging continuous electrical impedance distribution within the head.Conclusion The present Two-step MREIT algorithm is an effective method for imaging the continuous electrical impedance distribution within the human head.

AIM:Bioactive constituents were expected to be obtained from the roots of Angelica morri Hayata. METHOD:They were extracted with 95% alcohol and isolated by using column chromatography and recrystallization methods. The structures were elucidated by means of physico-chemical data and UV,IR,1HNMR, 13CNMR,and EIMS. The inhibitory effect on the constriction of rat aortic rings was induced by K+ or Ca2+. RESULT:3′S-(-)-hamaudol,3′S-(-)-Ο-acetylhamaudol,3′R-(+)-hamaudol,and (±)-hamaudol were isolated from the pieces of Radix Angelica Morri. The inhibitory rate of 3′S-(-)-Ο-acetylhamaudol and (±)-hamaudol on the above pharmacologic model appears the relation of quantity response. CONCLUSION:All the above compounds were found in this species for the first time,and(±)-hamaudol is a new. One of effect mechanisms of 3′S-(-)-Ο-acetylhamaudol and (±)-hamaudol diluted aorta could contribute to be inhibiting Ca2+ influx of vascular smooth muscle.

AIM:To obtain new typical compounds with dual mechanism,antagonizing Ca2+and inhibiting acetylcholinesterase,on Alzheimer's disease.METHODS:Resorcinol was chosen as primitive substrate,and AD-mix-β as asymmetrically dihydroxylated reagent;all products were screened against acetylcholinesterase in vitro.RESULTS:cis-3′R,4′R-disubstituted angular dihydropyranocoumarins were synthesized enantioselectively,however,its inhibitory activity on acetylcholinesterase is distinctively lower than that of cis-3′R,4′R-disubstituted linear dihydropyranocoumarins.

Meshless methods are recently developed numerical methods which require only node informa- tion. This paper introduces the basic principles and history of meshless methods, the principles and implementation of the moving least square method taking Galerkin method as an example. Finite points mixed method (FPMM) and its application in solving electrocardiogram(ECG) forward problem is also introduced. Foreground and problems need to be solved concerning the application of meshless methods in the study of ECG forward problem are discussed.

The study of water molecule self-diffusion process is of importance not only for getting anatomical information of brain inner tissue, but also for shedding light on the diffusion process of some medicine in brain tissue. In this paper, we summarized the self-diffusion model of water molecule in brain inner tissue, and calculated the self-diffusion coefficient based on Monte Carlo simulation under different conditions. The comparison between this result and that of Latour model showed that the two self-diffusion coefficients were getting closer when the diffusion time became longer, and that the Latour model was a long time-depended self-diffusion model.
Body Water ; metabolism ; Brain ; metabolism ; Cell Membrane Permeability ; Diffusion ; Diffusion Magnetic Resonance Imaging ; methods ; Extracellular Space ; metabolism ; Humans ; Models, Biological ; Monte Carlo Method