Recyclable V2O5/g-C3N4 Heterojunction-Catalyzed Visible-Light-Promoted C3-H Trifluoromethylation of Quinoxalin-2-(1H)-ones.

A visible-light-initiated C-H trifluoromethylation of quinoxalin-2(1H)-ones was established using a Z-scheme V2O5/g-C3N4 heterojunction as a recyclable photocatalyst in an inert atmosphere at room temperature under additive-free and mild conditions. A variety of trifluoromethylated quinoxalin-2-(1H)-one derivatives were heterogeneously generated in moderate to high yields, exhibiting good functional group tolerance. Remarkably, the recyclable V2O5/g-C3N4 catalyst could be reused five times with a slight loss of catalytic activity.

Functional force stimulation alters motor neuron discharge patterns.

Introduction: Beneficial effects have been observed for mechanical vibration stimulation (MVS), which are mainly attributed to tonic vibration reflex (TVR). TVR is reported to elicit synchronized motor unit activation during locally applied vibration. Similar effects are also observed in a novel vibration system referred to as functional force stimulation (FFS). However, the manifestation of TVR in FFS is doubted due to the use of global electromyography (EMG) features in previous analysis. Our study aims to investigate the effects of FFS on motor unit discharge patterns of the human biceps brachii by analyzing the motor unit spike trains decoded from the high-density surface EMG. Methods: Eighteen healthy subjects volunteered in FFS training with different amplitudes and frequencies. One hundred and twenty-eight channel surface EMG was recorded from the biceps brachii and then decoded after motion-artifact removal. The discharge timings were extracted and the coherence between different motor unit spike trains was calculated to quantify synchronized activation. Results and discussion: Significant synchronization within the vibration cycle and/or its integer multiples is observed for all FFS trials, which increases with increased FFS amplitude. Our results reveal the basic physiological mechanism involved in FFS, providing a theoretical foundation for analyzing and introducing FFS into clinical rehabilitation programs.

Simple Coumarin-Based Fluorescent Probe for Recognition of Pd(II) and Its Live Cell Imaging.

A simple coumarin hydrazine Schiff base bearing a thioether recognition fragment (compound CBBS) has been rationally designed and easily prepared. CBBS exhibited an excellent selectivity for Pd(II) and a low detection limit of 65 nM (S/N = 3). The fluorescence emission intensities of CBBS at 495 nm were linear to Pd(II) concentrations in a wide range from 0 to 80 µM. Moreover, CBBS has been well used in fluorescence imaging of Pd(II) in living A549 cells. CBBS as a simple coordination-based fluorescent probe will inspire the researchers to develop a polymer for selective detection and adsorption of Pd(II).

A Capacitive Electrocardiography System With Dedicated Noise-Cancellation Algorithms for Morphological Analysis.

OBJECTIVE: Capacitive electrocardiography (cECG) has been proposed for ambulatory cardiac health monitoring. However, due to the high sensitivity of capacitive electrodes to various noise sources, particularly the power-line interference (PLI) and motion artifacts (MA), the existing capacitive systems are only verified in terms of RR interval. The aim of the present study is to explore the feasibility of using cECG for morphological analysis, and thus to extract clinical meaningful parameters. METHODS: A capacitive electrode with active guarding is realized. A phase-locked-loop (PLL) based adaptive canceller is employed to remove PLI from the cECG. Wavelet analysis is adopted to cancel other noises. The developed capacitive system and algorithms are evaluated by real ECG measurements on 7 volunteers using 3-lead configuration. The correlation coefficient (CC) between the processed cECG and the wet ECG is calculated in two different conditions: with and without the QRS complex. Several frequently used diagnostic parameters, i.e., RR interval, QRS interval, P segment, T segment, ST segment, are extracted and compared with that obtained from the wet ECG. RESULTS: High CCs are observed between the cECG and the wet ECG in both conditions, i.e., 0.97±0.03 with the QRS complex and 0.92±0.07 without the QRS complex. Besides, RR interval extracted from the two different ECG signals are identical for each subject. Other diagnostic parameters are quite similar. SIGNIFICANCE: Our results suggest cECG to be reliable for ambulatory heart rate monitoring. The results also indicate the feasibility of using cECG for clinical diagnosis.

Influence of Electrode Configuration on Muscle-Fiber-Conduction-Velocity Estimation Using Surface Electromyography.

OBJECTIVE: Muscle fiber conduction velocity (MFCV) is an important myoelectric parameter and can be estimated by analysing surface electromyography (EMG). Among many factors, electrode configuration plays a key role on MFCV estimation. Most studies adopt bipolar configuration (BC) for CV estimation. However, a thorough understanding of the underlying mechanism is lacking, confusing the design of the most appropriate EMG measurement setup for CV estimation. The aim of this study is therefore to systematically investigate the influence of electrode configuration on MFCV estimation. METHODS: Four possible configurations are considered, including BC, monopolar configuration (MC), common average reference (CAR), and a special monopolar configuration (SMC) using a fixed channel on the active muscle as reference. For each configuration, mathematical models computing the time delay between adjacent channels are derived and evaluated by dedicated simulation as well as real EMG measurements. MFCV was calculated using the maximum likelihood algorithm with and without channel normalization. RESULTS: The simulation results are in line with the mathematical models. The CVs estimated from the real EMG with and without normalization are 4.3 ±0.7 and 7.2 ±3.7 m/s, 5.7 ±1.3 and 20.4 ±4.7 m/s, 9.0 ±3.4 and 20.6 ±9.8 m/s, and 5.5 ±2.5 and 5.5 ±2.4 m/s for BC, MC, SMC, and CAR, respectively. CONCLUSION: Our results show normalized BC to produce the most accurate CV estimation, in line with the mathematical models and the simulation results. SIGNIFICANCE: These findings enable a better understanding of the influence of electrode configuration on MFCV estimation, providing useful information for EMG measurement setup design aiming at MFCV studies.