Patterning the neuronal cells via inkjet printing of self-assembled peptides on silk scaffolds

The patterning of neuronal cells and guiding neurite growth are important for neuron tissue engineering and cell-based biosensors. In this paper, inkjet printing has been employed to pattern self-assembled I₃QGK peptide nanofibers on silk substrates for guiding the growth of neuron-like PC12 cells. Atomic force microscopy (AFM) confirmed the dynamic self-assembly of I₃QGK into nanofiber structures. The printed self-assembled peptide strongly adheres to regenerated silk fibroin (RSF) substrates through charge-charge interactions. It was observed that in the absence of I₃QGK, PC12 cells exhibited poor attachment to RSF films, while for RSF surfaces coated or printed with peptide nanofibers, cellular attachment was significantly improved in terms of both cell density and morphology. AFM results revealed that peptide nanofibers can promote the generation of axons and terminal buttons of PC12 cells, indicating that I₃QGK nanofibers not only promote cellular attachment but also facilitate differentiation into neuronal phenotypes. Inkjet printing allows complex patterning of peptide nanofibers onto RSF substrates, which enabled us to engineer cell alignment and provide an opportunity to direct axonal development in vitro. The live/dead assay showed that printed I₃QGK patterns exhibit no cytotoxicity to PC12 cells demonstrating potential for future nerve tissue engineering applications.     

Carbon-free nanoporous gold based membrane electrocatalysts for fuel cells

Nanoporous gold (NPG) membranes made by dealloying consist of a bicontinuous network of Au ligaments and open pore channels, which have gained considerable attention as a platform for the design of carbon-free electrodes for proton exchange membrane fuel cells (PEMFCs). Benefiting from a unique combination of high electronic conductivity, high surface area, and modifiable surface chemistry, these self-supporting membrane type electrodes allow integration of various structural functions required for specific electrode reactions and simultaneously facilitate the entire fuel cell kinetic process. In this review, we summarize the major research progresses in this area, with an emphasis on how to customize the surface structures of these three-dimensional electrocatalysts for desired fuel molecule oxidation and oxidant reduction. We will also discuss these designed structural characteristics that can be readily accommodated in membrane electrode assemblies (MEA), thus effectively bridging the technological gap between electrocatalysts’ intrinsic activities and their actual performances in fuel cells.     

基于等效均匀温度的车内热环境分析

通过计算流体力学(CFD)与人体热调节模型的耦合仿真,得到人体整体和各节段的等效均匀温度(EHT).对比空调送风速度、送风温度与太阳辐射强度对整体EHT、平均皮肤温度及各换热损失量的影响,得到各因素变化时所处的EHT舒适区,采用试验设计法和方差分析法,得到3个影响因素对整体EHT、各节段EHT、平均皮肤温度及干热损失量的贡献率,发现送风条件影响大于太阳辐射,其中送风温度的影响最显著.在此基础上,得到EHT的拟合方程,并提出基于拟合方程改进空调控制的新思路.     

In vitro study of human endothelial progenitor cells behaviour on nitrided Ni-free Ti–27Nb alloy

A superelastic Ni-free Ti–27Nb alloy has been synthesized and gas nitrided at high temperature to investigate its suitability for vascular implant applications. The cellular responses of human endothelial progenitor cells (EPCs) to both bare and nitrided Ti–27Nb alloy have been analyzed using Live/Dead staining, MTT assay, fluorescence microscopy and ELISA technique, as well as NiTi alloy for comparison. Live/Dead staining and MTT assay were performed to assess the cellular viability and proliferation, while fluorescence microscopy was used to analyze cell adhesion, cell morphology, and the expression of endothelial cell markers (VE-cadherin and von Willebrand factor). Secretion of the pro-inflammatory chemokine MCP (monocyte chemoattractant protein)-1 by the cells grown in contact with the analyzed materials was further verified using the enzyme-linked immunosorbent assay. The results obtained revealed that adhesion, spreading, viability, proliferation rate and phenotypic markers expression of EPCs were similar on the surfaces of Ti–27Nb and NiTi alloys. Cells exposed to nitrided Ti–27Nb surface exhibited significantly decreased inflammatory response, which may be beneficial for reducing in-stent restenosis incidence.     

放电功率对微晶硅薄膜的晶化调控及光电性质的影响

以SiCl_4和H_2为源气体、采用等离子体增强化学气相沉积(PECVD)技术在不同放电功率下沉积微晶硅薄膜,通过调节放电功率实现了微晶硅薄膜的晶化调控和光电性质的优化,并利用Langmuir探针和质谱计分别对等离子体空间的电子特性和中性基团进行在线检测,初步探讨了成膜的微观机理.     

掺杂与应力对ZrO2薄膜电子结构和光学性质的影响

利用基于密度泛函理论的第一性原理平面波超软赝势方法系统地研究了掺杂和应力对ZrO_2薄膜的电子结构与光学性质的影响.本文首先研究了Hf原子替代掺杂对ZrO_2薄膜物性的影响,研究结果表明,Hf原子掺杂减小了ZrO_2薄膜的带隙和态密度大小,可在一定程度上降低其表面缺陷电荷和漏电流.掺杂Hf原子后介电峰和吸收峰的值明显下降,同时介电峰和吸收峰的波形均出现了窄化现象,半高宽显著减小.本文也着重研究了不同应力下四方晶相ZrO_2薄膜物理性质变化及规律.研究发现压应力显著调控了ZrO_2薄膜的带隙以及价带顶和导带底附近的能带结构.施加应力后吸收峰的吸收范围和强度均显著增大,峰值对应的光子能量蓝移则表明对紫外光的吸收随着应力的增加有所增强.在低能量红外和可见光区域,施加压应力后ZrO_2薄膜的折射率变大,但在紫外线区域,压应力使ZrO_2薄膜的折射率呈现出先增大后减小的波动特性.上述研究结果为ZrO_2薄膜材料的设计与应用提供了理论依据.     

Ce3+-Nd3+共掺Y3Al5O12发光材料的合成及其近红外量子剪裁特性研究

以高温固相法合成一系列Ce~(3+)-Nd~(3+)共掺Y_3Al_5O_(12)(YAG)发光材料.通过荧光光谱测试证明,在YAG基质中Ce~(3+)-Nd~(3+)之间发生宽谱高效近红外量子剪裁,能量传递机理为合作能量下转换.在460 nm波长激发下,Ce~(3+)离子吸收一个可见光子跃迁至5d_1能级,然后将自身能量传递给两个邻近的Nd~(3+),进而发射出两个近红外光子.对样品的荧光衰减曲线分析可知,Ce~(3+)-Nd~(3+)之间的量子效率高达177.8%.通过Ce~(3+)-Nd~(3+)之间的量子剪裁,可将太阳光谱中能量较高的紫外-可见波段转换为近红外波段,有利于太阳光谱更好地被晶硅太阳能电池吸收和利用.     

FOXP3+调节性T细胞与免疫细胞治疗

 CD4⁺CD25⁺FOXP3⁺调节性T细胞（Treg）负责维持机体免疫稳态、调节免疫耐受。Treg细胞通过调控机体对外来或自身抗原的免疫应答水平,在抗自身免疫及抗肿瘤免疫中均发挥重要作用。深入分析了Treg细胞功能的分子机理,通过FOXP3⁺Treg细胞体外扩增或对其进行修饰改造,可以使其在不同组织及炎症微环境下特异性促进对机体的有益作用,减少副作用,这一现象会为免疫细胞治疗提供新思路与新策略。     

氧化锌基薄膜的制备及其光学性质的研究现状

ZnO作为制造高效率短波长发光和激光器件的理想材料,在磁学和电学等方面已经取得了巨大的研究进展,但是在掺杂状态对调控ZnO薄膜的发光行为方面至今鲜有报道。介绍了ZnO薄膜材料的基本结构和特性,综述了ZnO基薄膜的制备技术及其优缺点。此外,借助紫外发光和可见发光这两种发光机制,探讨了Co、Sn单掺及Co、Sn共掺ZnO薄膜的可见光发光特性,同时指出掺杂元素和掺杂量对薄膜能带结构的影响。最后,对ZnO基薄膜材料的应用工作和今后的发展方向进行了展望。     

不同基片生长γ'-Fe4N薄膜的结构及其磁学性能

采用直流磁控溅射方法, 保持氩气流量不变, 控制氮气的体积分数为10%,125%,15%, 分别用Si（100）单晶和SrTiO₃（100）单晶基片制备Fe N薄膜. 用X射线衍射(XRD)和振动样品磁强计(VSM)等方法对两种不同基片生长Fe N薄膜的结构及磁学性能进行表征. 结果表明: 在SrTiO₃（100）单晶基片上得到了单相γ′-Fe₄N薄膜, 与Si（100）基片上的样品相比, SrTiO₃（100）更有利于诱导γ′-Fe₄N薄膜的取向性生长; 当氮气的体积分数约为12.5%时, 制备单相γ′-Fe₄N薄膜的晶粒结晶度较好, 且饱和磁化强度较高, 矫顽力比Si（100）为基片获得的Fe N薄膜样品低, 软磁性能较好.