Decoding the Chemical Language of Motile Bacteria by Using High‐Throughput Microfluidic Assays

Motile bacteria navigate chemical environments by using chemoreceptors. The output of these protein sensors is linked to motility machinery and enables bacteria to follow chemical gradients. Understanding the chemical specificity of different families of chemoreceptors is essential for predicting and controlling bacterial behavior in ecological niches, including symbiotic and pathogenic interactions with plants and mammals. The identification of chemical(s) recognized by specific families of receptors is limited by the low throughput and complexity of chemotaxis assays. To address this challenge, we developed a microfluidic‐based chemotaxis assay that is quantitative, simple, and enables high‐throughput measurements of bacterial response to different chemicals. Using the model bacterium Escherichia coli, we demonstrated a strategy for identifying molecules that activate chemoreceptors from a diverse compound library and for determining how global behavioral strategies are tuned to chemical environments.     

Foldable Printed Circuit Boards on Paper Substrates

This paper describes several low‐cost methods for fabricating flexible electronic circuits on paper. The circuits comprise i) metallic wires (e.g., tin or zinc) that are deposited on the substrate by evaporation, sputtering, or airbrushing, and ii) discrete surface‐mountable electronic components that are fastened with conductive adhesive directly to the wires. These electronic circuits—like conventional printed circuit boards—can be produced with electronic components that connect on both sides of the substrate. Unlike printed circuit boards made from fiberglass, ceramics, or polyimides, however, paper can be folded and creased (repeatedly), shaped to form three‐dimensional structures, trimmed using scissors, used to wick fluids (e.g., for microfluidic applications) and disposed of by incineration. Paper‐based electronic circuits are thin and lightweight; they should be useful for applications in consumer electronics and packaging, for disposable systems for uses in the military and homeland security, for applications in medical sensing or low‐cost portable diagnostics, for paper‐based microelectromechanical systems, and for applications involving textiles.     

Robust generation of monodisperse droplets using a microfluidic step emulsification device with triangular nozzle

In this work, the droplet generation process in the microfluidic step emulsification chip with a triangular nozzle (SE-T) was investigated in the combination of visualization experiment and numerical simulation, through a comparison with a rectangular nozzle (SE-R). The flow regimes, including dripping, dripping-jetting transition, and jetting, were observed in the SE-T, among which the dripping is the preferred flow regime to generate monodispersed droplet with corresponding C.V. (coefficient of variation) of the droplet size smaller than 1.9%. Compared with the SE-R, the larger space and expanding structure of the triangular nozzle in the SE-T enhance the wall wetting effects, which induces earlier appearance and accelerates shrinking of the neck. As a result, the SE-T exhibits more robust droplet performance under the dripping regime, which produces the droplets with nearly unchanged size and higher monodispersity, especially little related to the variations of surfactant concentrations and dispersed phase flow rates.     

芳纶复合纸基摩擦材料的初步研究

本文采用高性能芳纶纤维和剑麻纤维为原料制备湿式成型纸基摩擦材料.初步探讨了原纸中两种纤维的配比、剑麻打浆度、芳纶纤维的长度和形态以及作为粘结剂的酚醛树脂的种类和上胶量等对纸基材料的力学性能和摩擦性能的影响,为进一步研究湿式成型纸基摩擦材料奠定基础.     

用于3种食源性致病菌核酸提取的微流控芯片制备

基于固相萃取原理中磁珠核酸提取法,设计了一种可适用于多种食源性致病菌DNA提取的微流控芯片.芯片主要包含裂解腔、清洗腔、洗脱腔、抽气孔、通气孔、气动阀、毛细管阀等结构,可以完成食源性致病菌核酸提取、纯化及顺序加载等操作.为了提高核酸提取质量浓度,对芯片通道的亲水处理时间及核酸提取过程中的孵育时间、磁珠混合次数及洗脱时间...