A theory of finite tensile deformation of double-network hydrogels

A continuum damage model was developed to describe the finite tensile deformation of tough double-network (DN) hydrogels synthesized by polymerization of a water-soluble monomer inside a highly crosslinked rigid polyelectrolyte network. Damage evolution in DN hydrogels was characterized by performing loading-unloading tensile tests and oscillatory shear rheometry on DN hydrogels synthesized from 3-sulfopropyl acrylate potassium salt (SAPS) and acrylamide (AAm). The model can explain all the mechanical features of finite tensile deformation of DN hydrogels, including idealized Mullins effect and permanent set observed after unloading, qualitatively and quantitatively. The constitutive equation can describe the finite elasto-plastic tensile behavior of DN hydrogels without resorting to a yield function. It was showed that tensile mechanics of DN hydrogels in the model is controlled by two material parameters which are related to the elastic moduli of first and second networks. In effect, the ratio of these two parameters is a dimensionless number that controls the behavior of material. The model can capture the stable branch of material response during neck propagation where engineering stress becomes constant. Consistent with experimental data, by increasing the elastic modulus of the second network the finite tensile behavior of the DN hydrogel changes from necking to strain hardening.     

非富勒烯受体DA'D型稠环单元的结构修饰及电池性能研究

近年来,设计和合成高性能非富勒烯受体(NFAs)材料已经成为太阳能电池研究领域的前沿课题。基于DA'D型稠环结构的NFAs由于具有吸光系数高、能级和带隙可调、结构易于修饰、分子可高效合成、光电学性能优异等优点而受到了越来越广泛的关注。在短短7年的时间里,能量转换效率(PCE)从3%~4%提高到18%。2019年初邹应萍等报道了一个优秀的受体分子Y6,与PM6共混制备单结电池,获得了15.7%的能量转换效率。Y6类受体材料的中心给电子单元为DA'D型稠环结构,缺电子单元(A')通过氮原子与两个给电子单元(D)并联形成稠环结构,这有助于降低前线分子轨道能级并增强吸收,同时与氮相连的两个烷基链和位于噻吩并噻吩β位的两个侧链则有助于提高溶解度及调节结晶性。自Y6问世以来,人们对分子的结构剪裁进行了深入的研究,并报道了数十种新的结构。在这些新的受体中,DA'D部分的结构裁剪对提高器件效率和太阳能电池的性能起着至关重要的作用。本文对A'、D单元和侧链结构修饰的研究进展进行了综述。通过选择几组受体,对最近报道的分子进行分类,并将它们的光学、电化学、电学和光电性质与精确的结构修饰相关联,从而对结构-性能关系进行全面概述。     

Enhanced Power Density of Alcohol Biofuel Cell by Polymer-assisted Crosslinks of 3D Graphene on Carbon Paper as the Bioanode

Herein, we successfully construct the 3D biocompatible graphene through crosslinking 2D graphene nanosheet onto carbon fiber paper with poly(diallyldimethylammonium chloride) (PDDA) as anode of the alcohol biofuel cell. Compared with the bioanode without 3D graphene, the current density and output power of PDDA-graphene-ADH bioanode is increased by 23 % and 41 % at a high concentration of ethanol at pH 8.9, suggesting the stabilization role of graphene in enzyme loading. The study provides us a deep analysis on structures and performances of the bioanode incl. electrochemistry, X-ray photoelectron spectra, and atomic force microscopy images, which is significant to develop the new methods to construct 3D porous electrodes in energy conversion device.     

Advances in rapid and effective break-in/conditioning/recovery of automotive PEMFC stacks

Automotive proton exchange membrane fuel cell stacks need to meet manufacturer specified rated beginning-of-life (BOL) performance before being assembled into vehicles and shipped off to customers. The process of “breaking-in” of a freshly assembled stack is often referred to as “conditioning.” It has become an intensely researched area especially in automotive companies, where imminent commercialization of fuel cell electric vehicles (FCEVs) demands a short, energy- and cost-efficient, and practical conditioning protocol. Significant advances in reducing the conditioning time from 1 to 2 days to as low as 4h or less, in some cases without the use of additional inert gases such as nitrogen, and with minimal use of hydrogen, and specialized test stations will be discussed.     

Enhancement of bioelectrochemical dioxygen reduction with oxygen-enriching materials

Bioelectrochemical dioxygen reduction reaction (ORR) catalyzed by multi-copper oxidases (MCOs) is a process of paramount importance occurring at the cathode of enzymatic biofuel cells (EBFCs), which is an energy harvester that holds promise of self-sustained implantable and wearable medical devices. The MCO biocathode is, however, frequently the limiting factor of a working EBFC. Besides the operational stability issue, enzymatic biocathodes are largely constrained by the relatively low solubility of dioxygen in aqueous solution. As an emerging topic, we here review the introduction of dioxygen-enriching materials to the cathodic bioelectrode for overcoming the dioxygen supply limitation, leading to improved ORR performance.     

原位液相透射电子显微镜及其在 纳米粒子表征方面的应用

近年来,基于透射电子显微技术、微纳加工技术和薄膜制造技术的发展,原位液相透射电子显微技术产生,为构建多种纳米级分辨率尺度下的微实验平台,发展新型纳米表征技术和众多领域的相关研究提供了途径.本文首先介绍了应用于原位液相透射电子显微技术的液体腔设计要求,然后介绍了液体腔的发展和典型的制备工艺,最后综述了近年来液体腔透射电子显微镜在纳米粒子成核和生长方面的应用研究,并探讨了该技术前沿发展面临的机遇和挑战.本文将为提高我国先进纳米表征技术和原子精准构筑技术提供相关讨论和支持.     

Hexagonal boron phosphide and boron arsenide van der Waals heterostructure as high-efficiency solar cell

The rapid development of two-dimensional (2D) materials offers new opportunities for 2D ultra-thin excitonic solar cells (XSCs). The construction of van der Waals heterostructure (vdWH) is a recognised and effective method of integrating the properties of single-layer 2D materials, creating particularly superior performance. Here, the prospects of h-BP/h-BAs vdW heterostructures in 2D excitonic solar cells are assessed. We systematically investigate the electronic properties and optical properties of heterogeneous structures by using the density functional theory (DFT) and first-principles calculations. The results indicate that the heterogeneous structure has good optoelectronic properties, such as a suitable direct bandgap and excellent optical absorption properties. The calculation of the phonon spectrum also confirms the well-defined kinetic stability of the heterstructure. We design the heterogeneous structure as a model for solar cells, and calculate its solar cell power conversion efficiency which reaches up to 16.51% and is higher than the highest efficiency reported in organic solar cells (11.7%). Our work illustrates the potential of h-BP/h-BAs heterostructure as a candidate for high-efficiency 2D excitonic solar cells.     

n型IBC太阳电池选择性发射极工艺研究

为提升n型叉指背接触(IBC)太阳电池的光电转换效率,采用丝网印刷硼浆和高温扩散的方式形成选择性发射极结构,研究了硼扩散和硼浆印刷工艺对电池发射极钝化性能和接触性能的影响。实验结果表明,在硼扩散沉积时间和退火时间一定的条件下,硼扩散通源(BBr₃)流量为100 mL/min,沉积温度为830 ℃,退火温度为920 ℃时,发射极轻掺杂(p⁺)区域的隐开路电压达到710 mV,暗饱和电流密度为12.2 fA/cm²。发射极局部印刷硼浆湿重为220 mg时,经过高温硼扩散退火,重掺杂(p⁺⁺)区域的隐开路电压保持在683 mV左右,该区域方块电阻仅46 Ω/□,金属接触电阻为2.3 mΩ·cm². 采用该工艺方案制备的IBC电池最高光电转换效率达到24.40%,平均光电转换效率达到24.32%,相比现有IBC电池转换效率提升了0.28个百分点。     

从废水到新能源:光催化燃料电池的优化与应用

随着经济的飞速发展,社会对能源的需求日益扩大,对工业废水的无害化处理也提出了更高的要求。光催化燃料电池 (photocatalytic fuel cell, PFC) 在燃料电池中引入半导体光催化材料作为电极,实现了有机污染物高效降解和同步对外产电的双重功能,在废水无害化与资源化利用方面具有潜在的应用价值。半导体光催化电极是PFC系统高效运行的核心组件,增强其可见光响应和光生载流子分离是提高PFC性能的关键策略。反应器结构设计和运行参数优化也有利于改善PFC性能。本文从PFC基本原理和应用入手,综述了PFC在环境污染物资源化处理中的研究进展,并详细阐述了提高PFC的污染控制性能和产电效率的优化手段,为进一步设计高效稳定的PFC系统并实现其在水污染控制和清洁能源生产中的应用提供理论指导。     

Synthesis,cytotoxicity, apoptosis and cell cycle arrest of a monoruthenium(II)-substituted Dawson polyoxotungstate

By 5-h reaction of cis-[Ru^IICl₂(DMSO)₄] (M2) with K₁₀[α₂-P₂W₁₇O₆₁] (M3) in ice-cooled, HCl-acidic aqueous solution, a water-soluble 1:2-type diamagnetic ruthenium(II) complex of formula K₁₈[Ru^II(DMSO)₂(P₂W₁₇O₆₁)₂]·35H₂O (M1) was unexpectedly obtained as an analytically pure, homogeneous tan-colored solid, in which two DMSO ligands are coordinated to the ruthenium(II) atom. The cytotoxic potential of the complex was tested on C33A, DLD-1, and HepG-2 cancer cells and human normal embryonic lung fibroblasts cell MRC-5; the viability of the treated cells was evaluated by MTT assay. The mode of cell death was assessed by morphological study of DNA damage and apoptosis assays. Compound M1 induced cell death in a dose-dependent manner, and the mode of cell death was essentially apoptosis though necrosis was also noticed. Cell cycle analysis by flow cytometry indicated that M1 caused cell cycle arrest and accumulated cells in S phase.