Electrokinetics is a preferred technique for microfluidic systems, but it is typically applied on fluids that are not too conductive ͑lower than 0.02 S / m͒, which excludes most biological applications. To solve this problem, this letter investigates microfluidic actuation by ac electrothermal ͑ACET͒ effect that was largely overlooked by the community. ACET originates from temperature gradients in the fluids, and it becomes more pronounced in more conductive fluids. This letter discusses two ACET pump designs, and pumping was demonstrated with biobuffers ͑e.g., lysogeny broth at 0.754 S / m͒.

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LncRNAs are involved in the initiation and progression of cancer. However, the molecular mechanism and diverse clinical prognosis of MIR31HG in head and neck squamous cell carcinoma (HNSCC) are still unclear. Our previous microarray analysis showed that lncRNA MIR31HG interacted with HIF1A may play an oncogenic role in laryngeal squamous cell cancer (LSCC). To determine whether lncRNA MIR31HG served as a poor prognosis factor and targeted HIF1A to facilitate cell proliferation and tumorigenesis in human HNSCC, we found MIR31HG and HIF1A were overexpressed in LSCC, MIR31HG overexpression or co-expression of HIF1A-positive and p21-negative could serve as a poor prognostic factor for LSCC patients. We further confirmed that MIR31HG promoted cell proliferation, cell cycle progression, and inhibited cell apoptosis in vitro and in vivo. The ingenuity pathway analysis and Western blot indicated that MIR31HG regulated cell cycle progression via HIF1A and p21 in HNSCC. The current results provide evidences for the role of MIR31HG in promoting HNSCC progression and identify MIR31HG as a prognostic biomarker and putative therapeutic target in HNSCC.Electronic supplementary materialThe online version of this article (10.1186/s12943-018-0916-8) contains supplementary material, which is available to authorized users.

AC electrokinetics has shown great potential for microfluidic functions such as pumping, mixing and concentrating particles. So far, electrokinetics are typically applied on fluids that are not too conductive (<0.02 S/m), which excludes most biofluidic applications. To solve this problem, this paper seeks to apply AC electrothermal (ACET) effect to manipulate conductive fluids and particles within. ACET generates temperature gradients in the fluids, and consequently induces space charges that move in electric fields and produce microflows. This paper reports two new ACET devices, a parallel plate particle trap and an asymmetric electrode micropump. Preliminary experiments were performed on fluids with conductivity at 0.224 S/m. Particle trapping and micropumping were demonstrated at low voltages, reaching approximately 100 microm/s for no more than 8 Vrms at 200 kHz. The fluid velocity was found to depend on the applied voltage as V(4), and the maxima were observed to be approximately 20 microm above the electrodes.

The development of polyimides (PIs) with a superheat resistance and a high thermal dimensional stability is required urgently for application in the rapidly growing area of flexible-display substrates. Based on an enhanced intermolecular interaction, 2,2′-p-phenylenebis­(5-amino­benzimidazole) (DP) that contains bis-benzimidazole was synthesized, and two series of its copolyimides (PI-a and PI-b) were prepared by copolycondensation with 5-amino-2-(4-aminobenzene)­benzimidazole (PABZ) and 5-amino-2-(3-aminobenzene)­benzimidazole (i-PABZ), respectively. The high density and packing coefficient of the resulting PIs caused by the strong intermolecular interaction from the hydrogen bonds and the charge-transfer complex provided the PI films with a very high glass-transition temperature (T g > 450 °C) and an extremely low coefficient of thermal expansion (CTE) below 10 ppm/K for PI-a. Such good thermal properties expand their application as high thermostable materials. Furthermore, the PI-b had a higher T g than PI-a, whereas the latter had lower CTE values because of the configuration difference of their polymer chains. These data indicate that the resultant thermostable copolyimides have potential application as a flexible-display substrate and provide a feasible method to improve the thermal properties by incorporating bis-benzimidazole moieties.

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