Biocatalytic Feedback-Controlled Non-Newtonian Fluids

Non-Newtonian fluids are ubiquitous in daily life and industrial applications. Herein, we report an intelligent fluidic system integrating two distinct non-Newtonian rheological properties mediated by an autocatalytic enzyme reaction. Associative polyelectrolytes bearing a small amount of ionic and alkyl groups are engineered: by carefully balancing the charge density and the hydrophobic effect, the polymer solutions demonstrate a unique shear thickening property at low pH while shear thinning at high pH. The urea-urease clock reaction is utilized to program a feedback-induced pH change, leading to a strong upturn of the nonlinear viscoelastic properties. As long as the chemical fuel is supplied, two distinct non-Newtonian states can be achieved with a tunable lifetime span. As a proof of concept, we demonstrate how the physical energy-driven nonequilibrium properties can be manipulated by a chemical-fueled process.     

平顶飞秒激光经圆锥透镜在熔融石英中成丝及超连续辐射

实验研究了平顶飞秒激光经圆锥透镜后在熔融石英中的成丝及超连续辐射.与高斯飞秒激光的成丝对比发现,平顶飞秒激光可以获得在圆锥透镜焦深区域内强度分布更为均匀的等离子体细丝,这一特征更有利于飞秒激光在固体介质中进行微纳加工等领域的应用.并且,在不损伤熔融石英的条件下,平顶飞秒激光成丝可以获得更高能量、更高转换效率的超连续辐射,这是因为若产生光强相近的细丝,平顶飞秒激光所需的初始激光能量更高,此激光能量下产生的细丝长度更长、均匀性更好.     

Boron(iii) β-diketonate-based small molecules for functional non-fullerene polymer solar cells and organic resistive memory devices

A class of acceptor–donor–acceptor chromophoric small-molecule non-fullerene acceptors, 1–4, with difluoroboron(iii) β-diketonate (BF₂bdk) as the electron-accepting moiety has been developed. Through the variation of the central donor unit and the modification on the peripheral substituents of the terminal BF₂bdk acceptor unit, their photophysical and electrochemical properties have been systematically studied. Taking advantage of their low-lying lowest unoccupied molecular orbital energy levels (from −3.65 to −3.72 eV) and relatively high electron mobility (7.49 × 10⁻⁴ cm² V⁻¹ s⁻¹), these BF₂bdk-based compounds have been employed as non-fullerene acceptors in organic solar cells with maximum power conversion efficiencies of up to 4.31%. Moreover, bistable resistive memory characteristics with charge-trapping mechanisms have been demonstrated in these BF₂bdk-based compounds. This work not only demonstrates for the first time the use of a boron(iii) β-diketonate unit in constructing non-fullerene acceptors, but also provides more insights into designing organic materials with multi-functional properties.

Boron(iii) β-diketonates have been demonstrated to serve as multi-functional materials in NFA-based OPVs and organic resistive memories.     

Direct Transformation of Arenols Based on C—O Activation

In the view of substrate availability, atomic efficiency and cost, directly using arenols as coupling partners in cross‐coupling, would be one of the most attractive goals. Up to date, many efforts have been made to activate the C—O bond of phenols with different strategies, for example, through in‐situ formed intermediates, through a catalytic reductive dearomatization‐condensation‐rearomatization sequence or catalytic deoxygenation. In this review, we summarized recent advances in cross‐couplings of arenols as the electrophiles via C—O activation.     

硼掺杂VO2（M）纳米棒的合成、相转变及光学特性

采用V2O5和硼酸为原材料,草酸为还原剂,在水热条件下,成功制备出硼(B)掺杂VO2(B)纳米棒,经Ar气环境退火后,得到了V1-xBxO2(M)系列样品。样品的结构、形貌和相转变温度分别用X-射线粉末衍射(XRD)仪、扫描电子显微镜(SEM)和差示扫描量热仪(DSC)等进行表征。用X-射线光电子谱(XPS)来表征样品的组份和元素的价态,样品的红外光吸收谱也被测量。结果显示,当B掺杂达到2.0at%时,V1-xBxO2(M)相的转变温度升高到75.03℃。这个升高的相转变温度可归因于B3+替代V4+引起VO6八面体的晶格畸变,以及局域晶格电子密度的降低。     

固相萃取-HPLC法同时测定滇龙胆中7种苯甲酸酯

建立了固相萃取-HPLC法同时测定滇龙胆中抗老年痴呆的7种主要成分gentiside G,gentiside H,gentiside I,gentiside A,gentiside J,gentiside B,gentiside K的含量的方法。滇龙胆样品经乙醇提取环己烷萃取后,用硅胶固相萃取小柱净化,HPLC-DAD对7种苯甲酸酯进行定量检测。7种苯甲酸酯类化合物在一定范围内线性关系良好,相关系数均大于0.999,加样回收率为92.8%~104.6%,RSD为0.8%~4.7%。不同产地龙胆样品中云南产滇龙胆苯甲酸酯含量高于其他产地龙胆,7种化合物中,gentiside B含量最高达0.3425μg/g,gentiside G含量最低只有8.5μg/g。方法为滇龙胆药材的质量控制和资源开发利用提供科学依据。