ABSTRACT
Brain computer interface is a control system between brain and outside devices by transforming electroencephalogram (EEG) signal. The brain computer interface system does not depend on the normal output pathways, such as peripheral nerve and muscle tissue, so it can provide a new way of the communication control for paralysis or nerve muscle damaged disabled persons. Steady state visual evoked potential (SSVEP) is one of non-invasive EEG signals, and it has been widely used in research in recent years. SSVEP is a kind of rhythmic brain activity simulated by continuous visual stimuli. SSVEP frequency is composed of a fixed visual stimulation frequency and its harmonic frequencies. The two-dimensional ensemble empirical mode decomposition (2D-EEMD) is an improved algorithm of the classical empirical mode decomposition (EMD) algorithm which extended the decomposition to two-dimensional direction. 2D-EEMD has been widely used in ocean hurricane, nuclear magnetic resonance imaging (MRI), Lena image and other related image processing fields. The present study shown in this paper initiatively applies 2D-EEMD to SSVEP. The decomposition, the 2-D picture of intrinsic mode function (IMF), can show the SSVEP frequency clearly. The SSVEP IMFs which had filtered noise and artifacts were mapped into the head picture to reflect the time changing trend of brain responding visual stimuli, and to reflect responding intension based on different brain regions. The results showed that the occipital region had the strongest response. Finally, this study used short-time Fourier transform (STFT) to detect SSVEP frequency of the 2D-EEMD reconstructed signal, and the accuracy rate increased by 16%.
Subject(s)
Humans , Algorithms , Brain , Physiology , Brain Mapping , Brain-Computer Interfaces , Electroencephalography , Evoked Potentials, Visual , Neural PathwaysABSTRACT
Collagen (Coll), as the basic material of matrix scaffolds for cell growth, has been widely used in the field of tissue engineering and regenerative medicine. In this study, collagen protein was modified by L-lysine (Lys), and cross-linked by genipin (GN) to prepare the L-lysine-modified collagen (Lys-Coll-GN) scaffolds. Microstructure, pore size, porosity, stability and biocompatibility of Lys-Coll-GN scaffolds were observed. The results showed that the bond between L-lysine and collagen protein molecule was formed by generating amide linkage, and mouse embryo fibroblasts proliferation was not inhibited in the Lys-Coll-GN scaffolds. In the multiple comparisons of Coll-scaf- folds, Coll-GN scaffolds and Lys-Coll-GN scaffolds, Coll-scaffolds was the worst in mechanical characteristics while the highest in biodegradation rate. Compared to Coll-GN scaffolds, Lys-Coll-GN scaffolds had more fiber structure, higher interval porosity (P<0. 01). Although the tensile stress of Lys-Coll-GN scaffolds reduced significantly, its e- longation length extended when the scaffolds was fractured (P<0. 01). The percentage of Lys-Coll-GN scaffolds residual weight was lower than that of Coll-GN scaffolds after all the scaffolds were treated by collagenase for 5 days (P<0. 01). This study suggested that Lys-Coll-GN scaffold had good biocompatibility, and it improved the mechanical property and degradation velocity for collagen-based scaffold. This study gave a new predominant type of tissue engineering scaffold for the regenerative medicine.
Subject(s)
Animals , Mice , Biocompatible Materials , Chemistry , Cell Proliferation , Collagen , Chemistry , Cross-Linking Reagents , Fibroblasts , Cell Biology , Iridoids , Chemistry , Lysine , Chemistry , Porosity , Tissue Engineering , Tissue ScaffoldsABSTRACT
Objective To prepare nifedipine (NP)skeleton frame sustained release tablets by adopting hydroxypropyl-beta-cy-clodextrin (HPC)and polyethylene glycol (PEG)as the matrix and to investigate its sustained release effect on NP.Methods NP skeleton frame sustained release tablets were prepared by the direct compression method after forming the inclusion complex with NP and HPC on a 1∶1 ratio and mixing with PEG.The in vitro drug release curves and the in vivo concentration-time curves of NP skeleton frame sustained release tablets were detected with the NP-PEG tablet without inclusion complex,NP-HPC tablet and NP powder capsule (NP capsule)as the control.Results The 5 h cumulative release rate of NP skeleton frame sustained release tablet in the simulated gastric fluid test(pH 1.2)was 36.4%,its sustained release effect was significantly stronger than that of the NP-HPC tablet group (80%,P<0.01)and the NP-PEG tablet group (100%,P<0.01).The in vivo test showed that AUC0-12 [(6 413±436)h/(ng·mL)],Cmax[(983±192)ng/mL]and tmax[(5.7±1.1)h]in the NP skeleton frame sustained release group were significantly higher than those in the NP-HPC tablet group,the NP-PEG tablet group and the NP Capsule group (all P<0.01 or 0.05).Conclusion NP skeleton frame sustained release tablets exhibits the sustained release effect on NP,can extend the NP in vitro release time,and improve the NP′s bioavailability,which is a novel NP sustained release tablet with excellent properties.
ABSTRACT
This paper dealt with the influences of different media, temperature, light and pH to the amount of oospore formation. The results showed that millet agar, bai yun beau agar and soybean agar provided the favorable condition for oospore formation, the number of oospores was 131.6~149.6 /cm2, but a few oospores was formation on frozen pea agar. The results also suggested that the optimal conditions for oospore formation were 18℃, pH7 and darkness. The oospores failed to be formed tinder fluorescent or black light.