Comparing Online Performance of EMG Pattern Recognition with and Without Joint Movements

Our previous study suggested that the subcutaneous muscle displacement caused by joint movements might alter muscle activation patterns and thus affect the classification performance.To further analyze the effect of joint movements on the online performance of Electromyography(EMG)Pattern Recognition(PR),this study assessed online classification performance with and without joint movements.EMG signals were recorded from the dominant forearm of 10 able-bodied subjects under two motion scenarios:Hand and Wrist Joints Unconstrained(HAWJU)and Constrained(HAWJC).Sixth-order autoregressive coefficients and four time-domain features were extracted from EMG signals.Linear Discriminant Analysis(LDA)models were trained to perform an online performance evaluation of the limb motions.The experimental results showed that the four online performance metrics:Motion Selection Time(MST),Motion Completion Time(MCT),Motion Completion Rate(MCR),and Online Classification Accuracy(ONCA)were 0.35 s,1.44 s,97.40%,and 82.61%for HAWJU and 0.37 s,1.47 s,89.70%,and 73.57%for HAWJC,respectively.The outcomes of this study indicated that subcutaneous muscle displacement due to joint movements has a positive effect on online classification performance.The absence of joint movements may be a physiological factor contributing to the poor online performance of the EMG-PR of transradial amputees.This study can provide a new perspective for improving the online performance of EMG-PR for transradial amputees.

Contents Variation Analysis ofγ-Amino Butyric Acid in Semen sojae praeparatum Fermentation Using Online Pre-Column Derivatization-HPLC

This paper reported the contents variation analysis ofγ-amino butyric acid(GABA)in Semen sojae praeparatum(SSP)which is a famous traditional Chinese medicine.High performance liquid chromatography(HPLC)was used and GABA was derivatized by online pre-column derivatization with o-phthalaldehyde(OPA).To validate this method,the precision,stability,repeatability and recovery were discussed.In the concentration range from 0.0125 to 0.400 mg/m L,the calibration curve for GABA was linear and the regression equation was obtained with correlation coefficient(R2)of 0.9999.Relatively high levels of GABA exist in SSP and the content changes of GABA at different time points during the fermenting process were detected.At the"yellow cladding"stage,GABA level was very low or even undetectable;the"secondary fermentation"stage witnessed a rapid increase of GABA content to 1.39-5.52 mg/g,which remained stable after 18 days of"secondary fermentation".This study demonstrated that GABA was generated at the"secondary fermentation"stage,revealing the significance and rationality of the"secondary fermentation"stage in the fermenting process of SSP.On the other hand,it suggested the downside of taking soy isoflavones as the only measurement in existing quality assessment and optimization approach for the fermenting process of SSP.