Vagus nerve stimulation (VNS) has become the most common non-pharmacological treatment for intractable drug-resistant epilepsy. However, the contribution of VNS to neurological rehabilitation following stroke has not been thoroughly examined. Therefore, we investigated the specific role of acute VNS in the recovery of cognitive functioning and the possible mechanisms involved using a cerebral ischemia/reperfusion (I/R) injury model in rats. The I/R-related injury was modeled using occlusion and reperfusion of the middle cerebral artery (MCAO/R) in Sprague–Dawley rats. VNS was concurrently applied to the vagus nerve using a stimulation intensity of 1 mA at a fixed frequency of 20 Hz with a 0.4-ms bipolar pulse width. The stimulation duration and inter-train interval were both 3 s. Next, Morris water maze and shuttle-box behavioral experiments were conducted to assess the effects of VNS on the recovery of learning, memory, and inhibitory avoidance following I/R injury. Intracerebroventricular injection of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride (DSP-4), a selective neurotoxin for noradrenergic neurons, was used to evaluate the role of norepinephrine (NE) as a mediator of therapeutic effects of VNS on cognitive recovery. Compared with the MCAO/R group, the VNS+MCAO/R group had improved spatial memory as indicated by swimming path lengths and escape latencies in the Morris water maze, and fear memory, as indicated by the avoidance conditioned response rate, mean shock duration, and avoidance time in shuttle-box behavior experiments. Compared with the VNS+MCAO/R group, the DSP-4+VNS+MCAO/R group, which had reduced NE levels in cortical and hippocampal brain regions, showed a reversal of the VNS-induced benefits on spatial and fear memory performance. VNS improves spatial and fear memory in a rat model of MCAO/R injury. However, a reduction in NE from the administration of DSP-4 blocks these protective effects, suggesting that NE may contribute to the influence exhibited by VNS on memory performance in rats with cerebral I/R-related injury.

Cell patterning has been widely used in research on fundamental cell biology and in applications such as tissue engineering, neuron network formation, cell based biosensor and drug screening. Although various methods have been developed, cell patterning in an enclosed microfluidic device at single cell level remains challenging. This paper describes a microfluidic device with microwells and protein patterns paired together in a single microchannel for an easy cell patterning. Cells captured in the microwells were positioned directly onto the protein patterns within 5 min and the patterning performance was successfully demonstrated using HeLa cells and human gallbladder carcinoma cells (SGC-996). Cells survived for 6 days in the microchannel. Cell attachment, migration, proliferation and cell colony formation were observed. Our device is free of topographic constraint for the patterned cells and no complex chemical modification to the substrate is needed, offering a simple, fast, and easy-to-operate way of patterning cells at single cell level in an enclosed microfluidic channel.

Due to assembling, manufacturing errors, and wear, irregular rough surfaces inevitably exist in joints, which will increase the contact stiffness nonlinearity at the joint of the spatial developable mechanism, and the traditional contact force model is difficult to accurately predict the contact force change of irregular rough surface clearance. Aiming at the difficulty of accurately predicting the dynamic behavior of the spatial developable mechanism caused by rough joint clearance, an improved clearance contact force modeling method based on an uncoordinated contact model is proposed in this paper. The influence of rough peak distribution on the contact area is analyzed. The stiffness of the traditional Hertz model is modified based on the probability distribution density function of the rough peak, and an improved contact force model based on dynamic contact stiffness is established. Based on the Lagrange multiplier method, the dynamics model of spatial developable mechanism is constructed. Based on the model, the dynamic analysis of the spatial expansion mechanism is carried out, and the influence of the roughness of the contact surface and the size of the clearance on the dynamic characteristics of the system are explored; as well, the influence of different clearance parameters on the dynamic characteristics of the development mechanism is revealed. Through the analysis, this paper provides a theoretical basis for predicting the effect of a spatial revolute clearance joint on the dynamic characteristics of the mechanism and lays a good foundation for the manufacture and application of the mechanism.