Robust,self-adhesive,and low-contact impedance polyvinyl alcohol/polyacrylamide dual-network hydrogel semidry electrode for biopotential signal acquisition

Herein,we fabricated a flexible semidry electrode with excellent mechanical performance,satisfactory self-adhesiveness,and low-contact impedance using physical/chemical crosslinked polyvinyl alcohol/polyacrylamide dual-network hydrogels(PVA/PAM DNHs)as an efficient saline reservoir.The resultant PVA/PAM DNHs showed admirable adhesive and compliance to the hairy scalp,facilitating the establishment of a robust electrode/skin interface for biopotential signal transmission.Moreover,the PVA/PAM DNHs steadily released trace saline onto the scalp to achieve the minimized potential drift(1.47±0.39 mV/min)and low electrode–scalp impedance(18.2±8.9 kΩ@10 Hz).More importantly,the application feasibility of real-world brain−computer interfaces(BCIs)was preliminarily validated by 10 participants using two classic BCI paradigms.The mean temporal cross-correlation coefficients between the semidry and wet electrodes in the eyes open/closed and the N200 speller paradigms are 0.919±0.054 and 0.912±0.050,respectively.Both electrodes demonstrate anticipated neuroelectrophysiological responses with similar patterns.This semidry electrode could also effectively capture robust P-QRS-T peaks during electrocardiogram recording.Considering their outstanding advantages of fast setup,user-friendliness,and robust signals,the proposed PVA/PAM DNH-based electrode is a promising alternative to wet electrodes in biopotential signal acquisition.

具有无界非线性项的广义逐段常变量微分方程拓扑等价函数的正则性

关于微分方程的拓扑等价以及拓扑等价函数的正则性一直是微分方程研究的焦点之一.当非线性项有界时,已经有很多学者证明了微分方程的拓扑等价函数是H?lder正则的.然而,当非线性项无界时,拓扑等价的正则性尚无突破性结果.在无界情形下, Zou和Shi(2017)得到了拓扑线性化的条件.除Zou和Shi(2017)给出的条件外,在附加的一个前提下,本文证明拓扑等价函数的H?lder正则性.事实上,当系统是有界时,系统线性化的条件足以保证其H?lder正则性.但是,当系统是无界时,这个附加条件是必不可少的.本文举例说明这个事实.这是首篇考虑无界系统拓扑等价H?lder正则的文章.

Finite volume effects on the QCD chiral phase transition in the finite size de-pendent Nambu-Jona-Lasinio model

The effective Lagrangian of a finite volume system should, in principle, depend on the system size. In the framework of the Nambu-Jona-Lasinio(NJL) model, by considering the influence of quark feedback on the effective coupling, we obtain a modified NJL model so that its Lagrangian depends on the volume. Based on the modified NJL model, we study the influence of finite volume on the chiral phase transition at finite temperature, and find that the pseudo-critical temperature of crossover is much lower than that obtained in the normal NJL model. This clearly shows that the volume dependent effective Lagrangian plays an important role in the chiral phase transitions at finite temperature.

Chiral phase diagram of strongly interacting matter at finite volume

At extremely high temperature T～200 Me V and low chemical potentialμ,the quarks and gluons get released from the nucleon and form the quark-gluon plasma(QGP)state,which is accessible in the heavy ion collisions(HIC)globally[1,2].Theoretically,ab initio lattice QCD simulation found the transition from hadrons to QGP at lowμis continuous crossover instead of phase transition.In this connection,RHIC is running the beam energy scan program to look into the territory with higherμ[3].One important goal is to determine if there is the first order phase transition as expected by many model studies and locate the critical end point(CEP)if it exists.

DELAY DIFFERENTIAL EQUATIONS UNDER NONLINEAR IMPULSIVE CONTROL AND APPLICATIONS TO NEURAL NETWORK MODELS

In this paper, a class of delay differential equations with nonlinear impulsive control is discussed. Based on the nonsmooth analysis, criteria of stability are obtained for delay differential equations with nonlinear impulses control under certain conditions. These criteria can be applied to some neural network models. At the end of the paper, two examples are provided to illustrate the feasibility and effectiveness of the proposed results.

In Vivo Study on Degradation Behavior and Histologic Response of Pure Magnesium in Muscles

When an orthopedics device is implanted into bone injury site, it will contact the soft tissue （skeletal muscle, fascia, ligament etc.） except for bone. Magnesium based biodegradable metals are becoming an important research object in orthopedics due to their bioactivity to promote bone healing. In this study, pure Mg rods with and without chemical conversion coating were implanted into the muscle tissue of rabbits. Implants and their surrounding tissues were taken out for weight loss measurement, cross- sectional scanning electron microscopy observation, elemental distribution analysis and histological examination. The results showed that the chemical conversion coating would increase the in vivo cor- rosion resistance of pure Mg and decrease the accumulation of calcium （Ca） and phosphorus （P） elements around the implants. For the bare magnesium implant, both Ca and P contents in the surrounding tissues increased at the initial stage of implantation and then decreased at 12 weeks implantation, while for the magnesium with chemical conversion coating, Ca and P contents in the surrounding tissues de- creased with the implantation time, but were not significant. The histological results demonstrated that there was no calcification in the muscle tissue with implantation of magnesium for up to 12 weeks. The chemical conversion coating not only increased the in vivo corrosion resistance of pure Mg, but also avoided the depositions of Ca and P in the surrounding tissues, meaning that pure magnesium should be biosafe when contacting with muscle tissues,