燃料电池用磺化聚醚醚酮质子交换膜的研究

通过浓硫酸磺化法制备了具有不同磺化程度的磺化聚醚醚酮(SPEEK),并对此种质子交换膜进行了物化性能和H2／O2质子交换膜燃料电池性能研究,实验结果表明,SPEEK膜具有较理想的力学稳定性和气体渗透率,它的微观结构和质子传导性能与Nafion膜有所不同,经过其H2／O2质子交换膜燃料电池的性能研究,SPEEK膜能够保证电池在200h内稳定运行,有希望成为PEMFC用质子交换膜材料。     

再铸Nafion膜的制备与应用

采用溶液－浇铸法用商业化Nafion膜的溶解液制备再铸Nafion膜，对再铸Nafion膜进行了氧气渗透系数测试和电池性能评价，并与厚度相近的商业化Nafion膜进行比较，同时对再铸Nafion膜组装的PEMFC进行了短期稳定性考查，实验结果表明：通过溶液－浇铸法制备的再铸Nafion 膜可以应用于质子交换膜燃料电池，再铸Nafion膜的氧气渗透系数和电池性能与商业化Nafion膜相近，再铸Nafion膜组装PEMFC在150h之内未见电池性能下降。     

离子液体在质子交换膜中的应用研究进展

质子交换膜是质子交换膜燃料电池(PEMFC)的核心元件之一,以Nafion为代表的全氟磺酸膜的电导率强烈依赖于水含量,而以磺化聚醚醚酮(SPEEK)为代表的磺化芳香族聚合物膜电导率依然有需要改善的空间,这些限制了PEMFC进一步的发展.离子液体具有较高的电导率,优异的热稳定性、电化学稳定性,且不挥发,因此可以替代水在高温下作为质子传递介质,应用于传统质子交换膜性能提升的改性,提高膜的质子电导率和使用温度.文章对近年来离子液体在SPEEK、PS、PBI、PI、PVDF、Nafion等树脂中的应用及质子传递机理进行了综述,阐述了应用中存在的问题及对策,并对研究前景进行了展望.     

质子交换膜Nafion(R)的导电性与物理老化

质子交换膜是质子交换膜燃料电池(PEMFC)的核心组成之一,它是一种选择透过性膜,不仅是隔膜材料,还是PEMFC的电解质.Nafion(R)膜是目前最常用的质子交换膜之一.本文通过比较三种Nafion(R)R膜和经过不同单电池运行时间Nafion(R)112膜的玻璃化转变温度(Tg)及离子电导率(σ),试图考察物理老化对其导电性能的影响.根据单电池寿命测试结果得到了Nafion(R)112膜老化的活化能(ΔH老化)为665.0kJ/mol.     

质子交换膜Nafion的导电性与物理老化

质子交换膜是质子交换膜燃料电池（PEMFC）的核心组成之一，它是一种选择透过性膜，不仅是隔膜材料，还是PEMFC的电解质。Nafion喉是目前最常用的质子交换膜之一。本文通过比较三种Naflon膜和经过不同单电池运行时间Nation 112膜的玻璃化转变温度（Tg）及离子电导率（σ），试图考察物理老化对其导电性能的影响。根据单电池寿命测试结果得到了Nafion 112膜老化的活化能（△H老化）为665．0kJ／mol。     

直接甲醇燃料电池用质子交换膜SPEEK/SGO/SPEEK的研究

采用无水对氨基苯磺酸(SA)对氧化石墨烯(GO)进行了磺化,并得到磺化氧化石墨烯(SGO),将磺化聚醚醚酮(SPEEK)膜包裹在SGO纸的两侧,制备了SPEEK/SGO/SPEEK膜作质子交换膜(PEM).通过膜性能表征可知,与SPEEK和SPEEK/GO/SPEEK膜相比,SPEEK/SGO/SPEEK膜的离子交换容量(IEC)提高,质子传导活化能(Ea)明显降低,甚至与Nafion*112膜相近,而其甲醇渗透率远低于Nafion*112膜.将膜组装成直接甲醇燃料电池(DMFC),经测试电池性能得到SPEEK/SGO/SPEEK组装的DMFC的最高能量密度在80℃和1mol/L甲醇浓度时可达42.1mW/cm~2,比商业Nafion*112膜组装的电池的最高能量密度高35.4%,明显优于SPEEK和SPEEK/GO/SPEEK膜,且电池稳定性良好,证明SPEEK/SGO/SPEEK膜在PEM的应用方面具有很大的潜力.     

面向氢空、无增湿操作条件的高保水性质子交换膜的制备与性能

作为质子交换膜燃料电池(PEMFC)的一个重要应用场景,开发满足无人机用的低温质子交换膜燃料电池(Low Temperature-PEMFC)正受到越来越多的关注。无人机所采用的PEMFC操作条件比较特殊,作为原料的H₂、空气均为无加湿的干气。针对这一特殊操作条件,需开发相应的具有保水能力的质子交换膜。为此,首先合成了一种具有高保水性的高分子树脂(PAAAM),将其加入Nafion溶液中混合均匀,利用溶液浇铸法制膜,探索并优化了PAAAM的加入量;随后,对保水复合膜进行了FTIR、SEM、质子传导率、保水性、溶胀率、拉伸强度、热失重性能等表征,并进行电池输出性能测试;最终结果表明:Nafion系质子交换膜在原料为干空气、干H₂的条件下,最适宜的操作温度区间为50~55℃。当PAAAM加入量为1.0wt%时,Nafion基复合膜(NFPAM1)具有更优的电池性能。当电池温度55℃、干燥H₂、空气流量分别为0.1 L·min?1和0.55 L·min?1时,采用NFPAM1复合膜的PEMFC最高功率密度为691 mW·cm?2。      

磺化聚砜/POSS杂化质子传导膜的制备及钒电池性能

将磺化度为62%的磺化聚砜(SPSf)与笼型倍半硅氧烷(POSS-NH_2)进行共混,得到系列SPSf/POSS-NH_2杂化质子传导膜,研究了POSS-NH_2含量对SPSf/POSS-NH_2膜的吸水率、面电阻、质子电导率、钒离子渗透率、机械强度、耐氧化性能及相应钒电池性能的影响.研究表明,添加POSS-NH_2后,热分解温度提高,质子电导率可达10.55 mS/cm, POSS-NH_2质量分数为5%的S-P-5%杂化膜钒离子渗透率降低至5.47×10~(-9) cm~2/min,质子选择性提高(1.930×10~6 S·min/cm~3),远优于Nafion115膜(1.23×10~5 S·min/cm~3)和纯SPSf膜(S-P-0%膜)(5.41×10~5 S·min/cm~3).与S-P-0%膜相比,S-P-5%膜为电池效率最佳,库伦效率可稳定维持在99.4%左右,高于Nafion115膜(92.38%)和S-P-0%膜(91.72%),电压效率和能量效率也得到明显提升,300次循环仍然具有较稳定的电池效率,自放电时间达117 h,是Nafion115膜的10倍,POSS的引入为SPSf质子传导膜性能的提升提供了新思路.     

低温燃料电池用聚(2,5-苯并咪唑)/磺化海泡石复合质子交换膜的制备与性能EI北大核心CSCD

采用原位法制备了一种适用于低温燃料电池的新型聚(2,5-苯并咪唑)/磺化海泡石(ABPBI/S-Sep)复合质子交换膜。对海泡石酸活化和磺化改性前后的化学结构、亲水性和分散性以及复合膜的形貌、吸水率、磷酸掺杂水平与质子传导率等性能进行了表征和测试。结果显示,所制备的S-Sep粒子在ABPBI聚合物基体中分散均匀,并能促进聚合物分子链的规整排布;与纯ABPBI膜相比,S-Sep粒子的添加显著增强了复合膜对水和磷酸的吸收和保留能力,且在相同或相近磷酸掺杂水平下,ABPBI/S-Sep复合膜的质子传导率显著提高。在40～90℃温度范围内,饱和湿度98%RH时复合膜的质子传导率与Nafion 212相当;在低湿度60%RH时,高磷酸掺杂水平的ABPBI/S-Sep复合膜质子传导率略低于98%RH的结果,但显著优于Nafion 212的质子传导性能。不同温湿度环境下的质子传导率结果表明S-Sep改性ABPBI复合膜具备低温环境使用的特点,可替代Nafion类全氟磺酸膜应用于低温质子交换膜燃料电池。     

DMFC用磺化聚醚醚酮膜的制备及改性研究

用磺化聚醚醚酮(SPEEK)替代传统的Nafion膜制备直接甲醇燃料电池(DMFC)用质子交换膜,能降低甲醇渗透率,提高质子导率,从而提高电池性能。介绍了SPEEK膜的制备方法及其缺点,综述了SPEEK膜有机和无机改性的方法,并提出了SPEEK膜多元改性的新设想。     

New trends for solar cell development and recent progress of dye sensitized solar cells

This article reviews the new concepts and new trends of solar cell development. To increase the photoelectric conversion efficiency, reduce the cost, and for application in a much broader field, thin film solar cell, flexible solar cell, and tandem solar cell have become important subjects to be studied. As the representative of the solar cells of the third generation, the progress and challenges of dye sensitized solar cell was also reviewed.     

Regulation of cell morphology and viability using anodic aluminum oxide with custom-tailored structural parameters

Anodic aluminum oxide (AAO) with independently controlled period, porosity, and height is used as the model surface to study the single structural parameter effect on breast cancer cell behaviors, including cell polarity and cell viability. It is found that the quantity of multipolar cells and cell viability increases as the nanodent period increases from 100 to 300 nm, while the number of bipolar cells has almost no change until there is a dramatic decrease as the period increases to 300 nm. After anodizing nanodents into nanopores, the numbers of both bipolar cells and the cell viability increase significantly with the porosity increase. However, as the porosity further increases and the nanopore changes into a nanocone pillar, most of the cells become nonpolar spheres and the cell viability decreases. Increasing the height of the nanocone pillar has little effect on the cell polarity; the cell viability increases slightly with the increase of the nanocone pillar height. These results reveal the influence of individual nanostructure parameters on the cell behavior, especially the cell polarity and the cell viability, which can help to design the surface to make the cell grow as desired.     

CIMS环境下的制造单元

本文着重介绍了在现代制造技术条件下，新型制造单元与传统的生产单元之间的区别、特点及其发展趋势。     

Overlap-Based Cell Tracker

In order to facilitate the extraction of quantitative data from live cell image sets, automated image analysis methods are needed. This paper presents an introduction to the general principle of an overlap cell tracking software developed by the National Institute of Standards and Technology (NIST). This cell tracker has the ability to track cells across a set of time lapse images acquired at high rates based on the amount of overlap between cellular regions in consecutive frames. It is designed to be highly flexible, requires little user parameterization, and has a fast execution time.     

Cell Mechanical and Physiological Behavior in the Regime of Rapid Mechanical Compressions that Lead to Cell Volume Change

Cells respond to mechanical forces by deforming in accordance with viscoelastic solid behavior. Studies of microscale cell deformation observed by high speed video microscopy have elucidated a new cell behavior in which sufficiently rapid mechanical compression of cells can lead to transient cell volume loss and then recovery. This work has discovered that the resulting volume exchange between the cell interior and the surrounding fluid can be utilized for efficient, convective delivery of large macromolecules (2000 kDa) to the cell interior. However, many fundamental questions remain about this cell behavior, including the range of deformation time scales that result in cell volume loss and the physiological effects experienced by the cell. In this study, a relationship is established between cell viscoelastic properties and the inertial forces imposed on the cell that serves as a predictor of cell volume loss across human cell types. It is determined that cells maintain nuclear envelope integrity and demonstrate low protein loss after the volume exchange process. These results define a highly controlled cell volume exchange mechanism for intracellular delivery of large macromolecules that maintains cell viability and function for invaluable downstream research and clinical applications.     

A minimum of two distinct heritable factors are required to explain correlation structures in proliferating lymphocytes

During the adaptive immune response, lymphocyte populations undergo a characteristic three-phase process: expansion through a series of cell divisions; cessation of expansion; and, finally, most of the accumulated lymphocytes die by apoptosis. The data used, thus far, to inform understanding of these processes, both in vitro and in vivo, are taken from flow cytometry experiments. One significant drawback of flow cytometry is that individual cells cannot be tracked, so that it is not possible to investigate interdependencies in the fate of cells within a family tree. This deficit in experimental information has recently been overcome by Hawkins et al. (Hawkins et al. 2009 Proc. Natl Acad. Sci. USA 106, 13 457–13 462 (doi:10.1073/pnas.0905629106)), who reported on time-lapse microscopy experiments in which B-cells were stimulated through the TLR-9 receptor. Cells stimulated in this way do not aggregate, so that data regarding family trees can be recorded. In this article, we further investigate the Hawkins et al. data. Our conclusions are striking: in order to explain the familial correlation structure in division times, death times and propensity to divide, a minimum of two distinct heritable factors are necessary. As the data show that two distinct factors are necessary, we develop a stochastic model that has two heritable factors and demonstrate that it can reproduce the key features of the data. This model shows that two heritable factors are sufficient. These deductions have a clear impact upon biological understanding of the adaptive immune response. They also necessitate changes to the fundamental premises behind the tools developed by statisticians to draw deductions from flow cytometry data. Finally, they affect the mathematical modelling paradigms that are used to study these systems, as these are widely developed based on assumptions of cellular independence that are not accurate.     

A scatter search approach with dispatching rules for a joint decision of cell formation and parts scheduling in batches

A joint decision of cell formation and parts scheduling is addressed for a cellular manufacturing system where each type of machine and part may have multiple numbers and parts must require processing and transferring in batches. The joint decision problem is not only to assign batches and associated machine groups to cells, but also to sequence the processing of batches on each machine in order to minimise the total tardiness penalty cost. A nonlinear mixed integer programming mathematical model is proposed to formulate the problem. The proposed model, within nonlinear terms and integer variables, is difficult to solve efficiently for real size problems. To solve the model for practical purposes, a scatter search approach with dispatching rules is proposed, which considers two different combination methods and two improvement methods to further expand the conceptual framework and implementation of the scatter search so as to better fit the addressed problem. This scatter search approach interactively uses a combined dispatching rule to solve a scheduling sub-problem corresponding to each integer solution visited in the search process. A computational study is performed on a set of test problems with various dimensions, and computational results demonstrate the effectiveness of the proposed approach.     

Regulation effect of osteoblasts towards osteocytes by silk fibroin encapsulation

Herein, the rational design micromilieus involved silk fibroin (SF)-based materials have been used to encapsulate the osteoblasts, forming an extracellular coated shell on the cells, which exhibited the high potential to shift the regulation of osteoblasts to osteocytes by encapsulation cues. SF coating treated cells showed a change in cell morphology from osteoblasts-like to osteocytes-like shape compared with untreated ones. Moreover, the expression of alkaline phosphatase (ALP), collagen I (Col I) and osteocalcin (OCN) further indicated a potential approach for inducing osteoblasts regulation, which typically accelerates calcium deposition and cell calcification, presenting a key role for the SF encapsulation in controlling osteoblasts behavior. This discovery showed that SF-based cell encapsulation could be used for osteoblasts behavior regulation, which offers a great potential to modulate mammalian cells’ phenotype involving alternating surrounding cues.