Metal ion-promoted fabrication of melanin-like poly(L-DOPA) nanoparticles for photothermal actuation

Melanin-inspired polymers are currently the focus of growing interest for a wide range of applications ranging from energy to biomedical area. Whilst researchers have made numerous attempts to prepare and utilize polydopamine nanoparticles(PDA NPs), they have made limited progress in developing and discovering another typical functional mimic of natural melanin, poly(levodopa)(P(L-DOPA)) NPs, probably due to the lack of facile synthetic strategies towards satisfactory structural and functional control of melanin-like NPs. Herein, we reported a one-pot preparation method towards P(L-DOPA) NPs with good yields and controllable size/property in an aqueous solution assisted by various metal ions(i.e., Ni(II), Mg(II), Ca(II), Fe(III), Mn(II), Co(II), Zn(II) and Cd(II)). Interestingly, the resulting P(L-DOPA) NPs exhibited enhanced light absorption and photothermal behaviors compared with well-established PDA NPs, which can be employed to further fabricate kinds of photothermal composite actuators with promising performances such as folding, switching, and forward-moving. This study offers a facile and robust way to synthesize new synthetic melanins beyond PDA, and facilitates further functional discovery and evolution of melanin-inspired polymers and composites.     

Understanding energetic disorder in electron-deficient-core-based non-fullerene solar cells

Recent advances in material design for organic solar cells(OSCs) are primarily focused on developing near-infrared nonfullerene acceptors, typically A-DA′D-A type acceptors(where A abbreviates an electron-withdrawing moiety and D, an electron-donor moiety), to achieve high external quantum efficiency while maintaining low voltage loss. However, the charge transport is still constrained by unfavorable molecular conformations, resulting in high energetic disorder and limiting the device performance. Here, a facile design strategy is reported by introducing the "wing"(alkyl chains) at the terminal of the DA′D central core of the A-DA′D-A type acceptor to achieve a favorable and ordered molecular orientation and therefore facilitate charge carrier transport. Benefitting from the reduced disorder, the electron mobilities could be significantly enhanced for the"wing"-containing molecules. By carefully changing the length of alkyl chains, the mobility of acceptor has been tuned to match with that of donor, leading to a minimized charge imbalance factor and a high fill factor(FF). We further provide useful design strategies for highly efficient OSCs with high FF.     

2020 Roadmap on Carbon Materials for Energy Storage and Conversion

Carbon is a simple, stable and popular element with many allotropes. The carbon family members include carbon dots, carbon nanotubes, carbon fibers, graphene, graphite, graphdiyne and hard carbon, etc. They can be divided into different dimensions, and their structures can be open and porous. Moreover, it is very interesting to dope them with other elements (metal or non‐metal) or hybridize them with other materials to form composites. The elemental and structural characteristics offer us to explore their applications in energy, environment, bioscience, medicine, electronics and others. Among them, energy storage and conversion are extremely attractive, as advances in this area may improve our life quality and environment. Some energy devices will be included herein, such as lithium‐ion batteries, lithium sulfur batteries, sodium‐ion batteries, potassium‐ion batteries, dual ion batteries, electrochemical capacitors, and others. Additionally, carbon‐based electrocatalysts are also studied in hydrogen evolution reaction and carbon dioxide reduction reaction. However, there are still many challenges in the design and preparation of electrode and electrocatalytic materials. The research related to carbon materials for energy storage and conversion is extremely active, and this has motivated us to contribute with a roadmap on ‘Carbon Materials in Energy Storage and Conversion’.     

Molybdenum Carbide‐Embedded Multichannel Hollow Carbon Nanofibers as Bifunctional Catalysts for Water Splitting

With the environmental pollution and non‐renewable fossil fuels, it is imperative to develop eco‐friendly, renewable, and highly efficient electrocatalysts for sustainable energy. Herein, a simple electrospinning process used to synthesis Mo₂C‐embedded multichannel hollow carbon nanofibers (Mo₂C‐MCNFs) and followed by the pyrolysis process. As prepared lotus root‐like nanoarchitecture could offer rich porosity and facilitate the electrolyte infiltration, the Mo₂C‐MCNFs delivered favourable catalytic activity for HER and OER. The resultant catalysts exhibit low overpotentials of 114 mV and 320 mV at a current density of 10 mA cm^?2 for HER and OER, respectively. Furthermore, using the Mo₂C‐MCNFs catalysts as a bifunctional electrode toward overall water splitting, which only needs a small cell voltage of 1.68 V to afford a current density of 10 mA cm^?2 in the home‐made alkaline electrolyzer. This interesting work presents a simple and effective strategy to further fabricating tunable nanostructures for energy‐related applications.     

交通载荷作用下跨海桥梁-电缆组合结构随机振动分析

电缆沿桥跨海铺设是海缆铺设的一种新的形式, 针对由汽车和列车交通载荷诱发的沿跨海桥梁敷设电缆的振动问题, 建立了桥梁-电缆的整体组合结构分析模型, 将汽车和列车的作用载荷简化为移动的随机集中载荷序列, 发展虚拟激励法(pseudo-excitation method, PEM)用于分析移动随机载荷作用下电缆位移和应力响应的标准差及演变功率谱 (power spectral density, PSD), 并研究了汽车和列车运行速度对电缆动力响应标准差的影响. PEM将移动随机载荷问题转化为特定频率简谐移动载荷作用下的动力响应分析, 能够计算得到与Monte Carlo (MC) 方法非常吻合的电缆动力响应标准差, 但所需的时域响应分析次数远少于MC方法. 数值结果表明, 随着汽车和列车运行速度的提升, 电缆位移和应力标准差呈现增大的趋势; 在汽车和列车交通载荷作用下, 铝护套的位移标准差和功率谱的值比缆芯要大, 这可能会使得电缆的疲劳破坏首先发生在铝护套层, 本文工作对电缆沿桥跨海铺设实际工程具有一定的借鉴意义.      

基于支座反力影响线曲率差分的等截面连续梁损伤识别方法

为了实现仅采用损伤状态信息对等截面连续梁进行损伤识别,通过推导三跨不等跨连续梁在移动荷载作用下的支座反力影响线,发现支座反力影响线求曲率并作差分后的曲线在损伤位置会发生突变,基于该现象提出了一种损伤定位方法,进一步建立了损伤程度计算方法,可对损伤程度进行较精确的定量。通过一三跨连续梁和一四跨连续梁工程实例的仿真分析,证明了支座反力影响线曲率差分指标损伤定位和相应的损伤程度定量方法对等截面连续梁损伤识别具有可行性。     

钨球对高硬度钢斜侵彻效应

为研究高硬度钢板抗不同着角钨球的侵彻性能及破坏模式,通过弹道枪进行了?8 mm、?11 mm钨合金球形破片以0°、20°、40°着角撞击厚度为6 mm、8 mm的高硬度钢板试验,得到了极限贯穿速度v₅₀;分析了钨球轴向径向变形及靶板失效模式与撞击速度的关系,发现高硬度钢板失效模式主要为压缩开坑破坏和沿厚度方向剪切破坏。采用有限元方法对试验进行了模拟,验证了数值模型及参数的合理性,并运用数值模拟方法研究了撞击着角对靶板吸能模式影响,结合试验数据,修正已有极限贯穿速度计算公式。结果表明:随侵彻着角增大,极限贯穿速度提高,且着角越大,极限贯穿速度增长越快;随着角增大,靶板吸能模式逐渐由压缩开坑向剪切冲塞过渡,且着角大于50°时,剪切冲塞耗能将超过压缩开坑耗能;修正后极限贯穿速度计算公式适用范围更广、精度更高,具有较好工程应用价值。     

Time‐dependent Density Functional Theory Study on the Hydrogen‐bonded Dimers Formed by Gauche‐1PA and Trans‐1PA

Three hydrogen bonding complexes of the gauche‐1PA dimer (GG), trans‐1PA dimer (TT) and mixed dimer (GT) have been calculated for the geometry conformations and excited‐state energies. The electron distribution at the site of C‐O of H‐donor moiety in HOMO transfers to the direction of O‐H of H‐acceptor moiety in LUMO. The hydrogen bond between two 1PAs is the bridge of the intermolecular charge transfer. By the Zhao and Han's excited‐state hydrogen bonding dynamics rule, the first excited‐state hydrogen bonding change has been discussed without optimizing the excited‐state geometry conformations. According to the distinct difference between GT and GG (TT), we concluded that two gauche‐1PA monomers of one dimer are transformed at the same time to two trans‐1PA monomers.     

以DNA为靶点的钌(Ⅱ)配合物的合成、晶体结构和抗肿瘤活性

为开发新型钌(Ru)抗肿瘤药物,以3-甲基-2-噻吩甲醛-4-羟基苯甲酰肼席夫碱配体(L)合成了[Ru(L)(DMSO)_2Cl_2](1)(DMSO=二甲基亚砜)。用X射线单晶衍射法测定了1的晶体结构。配合物1的结构由1个Ru(Ⅱ)中心离子与2个DMSO分子、2个氯离子、1个L配位而成。通过MTT实验分析,1对T24细胞表现出良好的抗肿瘤活性。同时,通过彗星实验、蛋白质印迹实验和DNA琼脂糖凝胶电泳实验结果证明1可以有效结合DNA,诱导DNA损伤,最终杀死肿瘤细胞。导致DNA损伤的原因很可能是由于细胞与1孵育后细胞内可以产生大量的活性氧。     

Thermally induced structural transformation of polytriazoleimide to polyindoleimide

A new kind of polytriazoleimide containing bisphenyl-l,2,3-triazole（BPT） was synthesized by copper-catalyzed 1,3-dipolar cycloaddition of azides and alkynes（CuAAC） and polycondensation.The thermal stability and degradation mechanism of the polytriazoleimide were investigated.The results show that the structure of BPT in polytriazoleimide transforms to phenylindole after thermal treatment,accompanying the release of N₂.