Grubbs Catalysts Immobilized on Merrifield Resin for Metathesis of Leaf Alcohols by using a Convenient Recycling Approach

Three new types of heterogeneous catalysts were prepared using a facile approach by the immobilization of Grubbs catalysts on PEGylated Merrifield resin. One of the immobilized catalysts was more efficient than the free catalyst for the metathesis of leaf alcohols in conversion and selectivity and was reused repeatedly (up to 5 cycles) with only a slight loss of activity (10.5 %). The long-chain PEGylated linker provided an appropriate distance between the resin and the catalytic center so that the ruthenium catalysts acted as the free catalyst.     

锰离子氧化沉淀法实现锂离子电池LiNi0.8Co0.05Mn0.15O2材料的回收和利用

以浓盐酸为浸出剂,以NaOH和NH₄HCO₃为沉淀剂,利用Mn²⁺在碱性条件下的氧化反应改变离子的沉淀次序进而分步回收的方案,探究了浓盐酸酸浸处理三元正极材料LiNi_0.8Co_0.05Mn_0.15O₂的最佳条件。在分步沉淀过程中,Mn²⁺被氧化为不溶于非还原性酸的MnO （OH）₂,并在酸性条件下回收。Ni、Co则在碱性条件下利用NaOH回收,而Li则利用NH₄HCO₃回收。该方法中Mn的回收率达到85.1%,产品纯度达到98.6%; Li的回收率达到95.0%,产品纯度达到99.3%。由回收材料重新合成的三元正极组装的软包电池的首圈放电比容量达到了175 mAh·g^-1,可以以超过99.5%的库仑效率稳定循环50圈。     

可再生纤维素/环糊精聚合物对水中亚甲基蓝吸附行为

利用甘蔗渣提取纤维素修饰环糊精聚合物,成功制备可再生纤维素/环糊精聚合物（SUG-EPI-CDP）吸附剂。采用傅利叶红外光谱仪（FT-IR）与热重分析仪（TGA）对材料进行表征,同时考察了该材料对水中亚甲基蓝（MB）吸附特性和机理的影响。结果表明：在溶液pH值为7、温度为30 ℃的条件下,SUG-EPI-CDP可在120 min内有效去除MB,去除率达80.9%。通过模型拟合发现,SUG-EPI-CDP对MB的吸附是自发且吸热的过程,符合准二阶动力学方程和Langmuir等温线模型。该吸附剂实验最大吸附量达8.1 mg/g,远高于其他废料所制备的吸附剂。结果表明,利用可再生纤维素修饰可有效提高环糊精聚合物的吸附性能,同时为甘蔗渣资源化利用提供了新途径。     

Development of a general separation strategy by countercurrent chromatography using sanshools from Zanthoxylum bungeanum oleoresin as a case study

Three kinds of sanshools were separated from Zanthoxylum bungeanum oleoresin by high-speed countercurrent chromatography. Sanshools are a series of amide compounds extracted from the Zanthoxylum bungeanum. Due to similar structures, polarities, and dissociation constants, it was challenging to select an appropriate solvent system for their complete separation by countercurrent chromatography. To address this challenge, a solvent-system-selection strategy was proposed to identify a relatively suitable solvent system. Additionally, a separation procedure incorporating multi-elution modes selection was established to separate similar compounds in a logical order. Ultimately, a solvent system comprising n-hexane:ethyl acetate:methanol:water in a ratio of 19:1:1:5.67 was selected. Three amide compounds with high purity were obtained through the use of recycling elution mode to improve separation resolution: hydroxy-ε-sanshool (8.4 mg; purity: 90.64%), hydroxy-α-sanshool (326.4 mg; purity: 98.96%), and hydroxy-β-sanshool (71.8 mg; purity: 98.26%) were obtained from 600 mg sanshool crude extract. The summarized solvent-system-selection strategy and separation procedure incorporating multi-elution modes may instruct countercurrent chromatography users, particularly novices, seeking to separate compounds with highly similar chemical properties.     

Advances in Targeting Drug Biological Carriers for Enhancing Tumor Therapy Efficacy

Chemotherapy drugs continue to be the main component of oncology treatment research and have been proven to be the main treatment modality in tumor therapy. However, the poor delivery efficiency of cancer therapeutic drugs and their potential off-target toxicity significantly limit their effectiveness and extensive application. The recent integration of biological carriers and functional agents is expected to camouflage synthetic biomimetic nanoparticles for targeted delivery. The promising candidates, including but not limited to red blood cells and their membranes, platelets, tumor cell membrane, bacteria, immune cell membrane, and hybrid membrane are typical representatives of biological carriers because of their excellent biocompatibility and biodegradability. Biological carriers are widely used to deliver chemotherapy drugs to improve the effectiveness of drug delivery and therapeutic efficacy in vivo, and tremendous progress is made in this field. This review summarizes recent developments in biological vectors as targeted drug delivery systems based on microenvironmental stimuli-responsive release, thus highlighting the potential applications of target drug biological carriers. The review also discusses the possibility of clinical translation, as well as the exploitation trend of these target drug biological carriers.     

Recycling Application of Li–MnO2 Batteries as Rechargeable Lithium–Air Batteries

The ever‐increasing consumption of a huge quantity of lithium batteries, for example, Li–MnO₂ cells, raises critical concern about their recycling. We demonstrate herein that decayed Li–MnO₂ cells can be further utilized as rechargeable lithium–air cells with admitted oxygen. We further investigated the effects of lithiated manganese dioxide on the electrocatalytic properties of oxygen‐reduction and oxygen‐evolution reactions (ORR/OER). The catalytic activity was found to be correlated with the composition of Li_xMnO₂ electrodes (0<x<1) generated in situ in aprotic Li–MnO₂ cells owing to tuning of the Mn valence and electronic structure. In particular, modestly lithiated Li_0.50MnO₂ exhibited superior performance with enhanced round‐trip efficiency (ca. 76 %), high cycling ability (190 cycles), and high discharge capacity (10 823 mA h g_carbon^?1). The results indicate that the use of depleted Li–MnO₂ batteries can be prolonged by their application as rechargeable lithium–air batteries.     

Electro‐oxidation and reduction of H2 on platinum studied by scanning electrochemical microscopy for the purpose of local detection of H2 evolution

Electrochemical detection of H₂ using scanning electrochemical microscopy (SECM) has shown to hold great promise as a sensitive characterization method with high spatial resolution for active surfaces generating H₂. Herein, the factors contributing to the current that is measured by SECM in generation/collection mode for H₂ detection are studied. In particular, the concentration gradient of H₂ at the substrate, the H₂/H⁺ recycling between the SECM tip and substrate and hemispherical profile of H₂ diffusion has been discussed. It was postulated that H₂/H⁺ recycling plays a dominant role in the oxidative current measured in generation/collection mode of SECM when the microelectrode is positioned in close vicinity of substrate. Copyright © 2015 John Wiley & Sons, Ltd.     

基于酶辅助靶标循环的适体传感器灵敏检测中药中黄曲霉毒素B1

该文基于酶辅助靶标循环信号放大策略构建了用于黄曲霉毒素B1(AFB1)高灵敏检测的化学发光适体传感器。以G-四链体/氯化血红素DNA酶为信号分子设计了免标记的适体探针H1-S1和发夹探针H2。适体探针结合目标AFB1,在核酸外切酶I辅助下,触发靶标循环反应产生发夹H1。发夹H1与H2杂交,释放出完整的G-四链体序列,并进一步与氯化血红素结合形成G-四链体/氯化血红素DNA酶。DNA酶通过催化氧化鲁米诺-H2O2化学发光体系产生化学发光信号,实现AFB1的放大检测。在最优实验条件下,化学发光强度与AFB1质量浓度的对数在0.001~100 ng/mL范围内呈良好的线性关系,相关系数(r2)为0.9955,检出限为0.93 pg/mL,回收率为93.7%~107%。该适体传感器操作简单、灵敏度高、特异性好,在黄曲霉毒素污染检测方面具有良好的应用前景。     

Photoinduced Iron‐Based Water‐Induced Phase Separable Catalysis (WPSC) ICAR ATRP of Poly(ethylene glycol) Methyl Ether Methacrylate

Iron‐mediated atom transfer radical polymerization (ATRP) has gained extensive attention because of the superiority of iron catalysts, such as low toxicity, abundant reserves, and good biocompatibility. Herein, a practical iron catalyst recycling system, photoinduced iron‐based water‐induced phase separable catalysis ATRP with initiators for continuous activator regeneration, at room temperature is developed for the first time. In this polymerization system, the polymerization is conducted in homogenous solvents consisting of p‐xylene and ethanol, using commercially available 5,10,15,20‐tetraphenyl‐21H,23H‐porphine iron(III) chloride as the iron catalyst, ethyl 2‐bromophenylacetate as the ATRP initiator, 2,4,6‐trimethylbenzoyl diphenylphosphine oxide as the photoinitiator, and poly(ethylene glycol) methyl ether methacrylate as the model hydrophilic monomer. After polymerization, a certain amount of water is added to induce the phase separation so that the catalyst can be separated and recycled in p‐xylene phase with very low residual metal complexes (<12 ppm) in the resultant polymers even after six times recycle experiments.

     

硫化天然橡胶的本征自修复与固相回收加工

通过小分子模拟试验和应力松弛,发现甲基丙烯酸铜(MA-Cu)比氯化铜(CuCl_2)更适合用作硫化天然橡胶中二硫键交换反应催化剂,并且硫化天然橡胶中的二硫键交换反应需要在高于120°C的温度下才能高效进行,这保障了相关制品在较低温工作时的结构与性能稳定.进一步的实验结果表明,硫化天然橡胶在MA-Cu辅助作用下获得了多次自修复与固相回收加工性能,损伤自修复后的硫化天然橡胶与固相回收加工的再生硫化天然橡胶,其拉伸强度均可恢复到原始材料强度的80%左右.