Investigation on the structure,fluoride vaporization and crystallization behavior of CaF2–CaO–Al2O3–(SiO2) slag for electroslag remelting

Journal of Thermal Analysis and Calorimetry - The structure, vaporization behavior and crystallization of CaF2–CaO–Al2O3 slags with different SiO2 contents for electroslag remelting...     

Chemical‐Reductant‐Free Electrochemical Deuteration Reaction using Deuterium Oxide

We report a method for the electrochemical deuteration of α,β‐unsaturated carbonyl compounds under catalyst‐ and external‐reductant‐free conditions, with deuteration rates as high as 99 % and yields up to 91 % in 2 h. The use of graphite felt for both the cathode and the anode was key to ensuring chemoselectivity and high deuterium incorporation under neutral conditions without the need for an external reductant. This method has a number of advantages over previously reported deuteration reactions that use stoichiometric metallic reductants. Mechanistic experiments showed that O₂ evolution at the anode not only eliminates the need for an external reductant but also regulates the pH of the reaction mixture, keeping it approximately neutral.     

Irreversible Amide‐Linked Covalent Organic Framework for Selective and Ultrafast Gold Recovery

Design of stable adsorbents for selective gold recovery with large capacity and fast adsorption kinetics is of great challenge, but significant for the economy and the environment. Herein, we show the design and preparation of an irreversible amide‐linked covalent organic framework (COF) JNU‐1 via a building block exchange strategy for efficient recovery of gold. JNU‐1 was synthesized through the exchange of 4,4′‐biphenyldicarboxaldehyde (BA) in mother COF TzBA consisting of 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)trianiline (Tz) and BA with terephthaloyl chloride. The irreversible amide linked JNU‐1 gave good stability, unprecedented fast kinetics, excellent selectivity and outstanding adsorption capacity for gold recovery. X‐ray photoelectron spectroscopy along with thermodynamic study and quantum mechanics calculation reveals that the excellent performance of JNU‐1 for gold recovery results from the formation of hydrogen bonds C(N)?H???Cl and coordinate interaction of O and Au. The rational design of irreversible bonds as both inherent linkage and functional groups in COFs is a promising way to prepare stable COFs for diverse applications.     

Copper-thioguanine metallodrug with self-reinforcing circular catalysis for activatable MRI imaging and amplifying specificity of cancer therapy

For chemotherapy, drug delivery systems often suffer from the inefficient drug loading capability, which usually cause systems toxicity and extra burden to excrete carrier itself. Moreover, the cancer therapeutic efficacy is also greatly limited by the specificity of tumor microenvironment for reactive oxygen species(ROS) based cancer therapeutic strategy(e.g., chemodynamic therapy). Herein, we have developed metal-drug coordination nanoplatform that can not only be responsive to tumor microenvironment but also modulate it, so as to achieve efficient treatment of cancer. Excitingly, by employing small molecule drug(6-thioguanine) as ligand copper ions, we achieve a high drug loading rate(60.1%) and 100% of utilization of metal-drug coordination nanoplatform(Cu-TG). Interestingly, Cu-TG possessed high-efficiently horseradish peroxidase-like, glutathione peroxidase-like and catalase-like activity. Under the tumor microenvironment, Cu-TG exhibited the self-reinforcing circular catalysis that is able to amplify the cellular oxidative stress, inducing notable cancer cellular apoptosis. Moreover, Cu-TG could be activated with glutathione(GSH) and facilitated for GSH triggered 6-TG release, higher selective therapeutic effect toward cancer cells, and GSH activated T_1 weight-magnetic resonance imaging. Based on the above properties, Cu-TG exhibited magnetic resonance imaging(MRI) guiding, efficient and synergistic combination of chemodynamic and chemotherapy with self-reinforcing therapeutic outcomes in vivo.     

Palladium-catalyzed regioselective cascade reaction of carbon dioxide,amines and allenes for the synthesis of functionalized carbamates

A palladium-catalyzed regioselective three-component cascade reaction of carbon dioxide,amines and allenes has been developed,providing an expedient and practical method for the construction of a range of functionalized carbamates containing dihydrobenzofuran or indole moiety in moderate to excellent yields.The broad substrate scope,good functional group tolerance and excellent chemo-and regioselectivity are the features of the transformation.     

Ab initio SCF structure investigation of β-hydroxypropionic acid and 3-aminopropionamide

The potential energy surfaces of β-hydroxypropionic acid and 3-aminopropionamide have been investigated by means of RHF /4-31G calculations. Structures, reaction paths for internal rotations, and the respective energy barriers are reported. The influence of the various intramolecular interactions on structural and energetical properties is shown and compared to the results previously obtained for β-alanine. © 1996 John Wiley & Sons, Inc.     

蓝色长余辉光致荧光粉的研究

高温固相反应合成了蓝色长余辉光致荧光材料CaAl2O4∶Eu2 ,Nd3 ,La3 ,激发后在暗室中观察,余辉的颜色为蓝色。进行了添加辅助激活剂的实验,首次在CaAl2O4∶Eu2 ,Nd3 中添加La3 。测定了该长余辉材料的激发光谱、发射光谱、余辉亮度和可视余辉时间,并对长余辉发光机理进行了探讨。余辉发射光谱的峰值波长为440nm,可视余辉时间达到18h以上。波长为280~380nm的光都可将该材料激发。实验结果表明,添加辅助激活剂La3 ,延长了CaAl2O4∶Eu2 ,Nd3 的可视余辉时间。在CaAl2O4∶Eu2 ,Nd3 ,La3 中,Eu2 是发光离子,Nd3 和La3 是辅助激活剂,发射光谱由Eu2 的激发态4f65d到基态4f7的电子跃迁产生。     

采用光纤和YAP晶体的小型γ相机的蒙特卡罗模拟

基于波长位移光纤(WSF)耦合YAP晶体中的光子传输特性,用GEANT4软件包建立了一个蒙特卡罗模拟程序.对采用波长位移光纤耦合平板式YAP晶体的小型单管γ相机的性能进行了计算机模拟.采用波长位移光纤耦合光电倍增管光阴极面的读出方式,和晶体直接耦合光电倍增管光阴极面相比,在相同的晶体面积大小条件下,PSPMT光阴极面积可大大缩小,使费用降低.模拟结果表明：γ射线与晶体发生作用的地方所对应的光纤输出的平均光子数最少为15个,位置灵敏光电倍增管完全可以探测到.说明采用闪烁晶体－WSF－位置灵敏光电倍增管的读出方式是可行的;在用硅油耦合波长位移光纤和YAP晶体的情况下,获得的空间分辨率为1.28 mm(FWHM).模拟结果也说明了增加平均光子数对提高空间分辨率的重要性.     

A compact Raman microprobe/microscope: Analysis of polydiacetylene Langmuir and Langmuir-Blodgett films

A compact Raman microprobe/microscope has been developed which contains no wavelength dispersive elements. Multilayer dielectric filters, tuned by rotation, provide sufficient wavelength selectivity for taking Raman spectra and forming Raman images of samples as small as 1 μm in diameter. The application of the instrument is demonstrated by Raman spectra and images of polydiacetylene Langmuir and Langmuir-Blodgett films.