An efficient synthesis of 3-(N-piperidinemethyl)-2,2,5,5-tetramethyl-1-oxy-3-pyrroline,a promising radioprotector for cancer radiotherapy

Nitroxides can ameliorate the toxic effects of radiation during cancer therapy. Nitroxides are paramagnetic and can be used in magnetic resonance imaging (MRI) and electron paramagnetic resonance imaging (EPRI) to monitor in vivo oxidative stress status. Compound 5 (3-(N-piperidinemethyl)-2,2,5,5-tetramethyl-1-oxy-3-pyrroline) was found to be the most effective nitroxide radioprotector. An efficient synthesis for this promising radioprotector was developed.     

Pd-catalyzed assembly of phenanthridines from aryl ketone O-acetyloximes and arynes through C–H bond activation

Pd-catalyzed annulation of aryne and aryl ketone O-acetyloxime via C–H bond activation was realized. Through the C–H bond activation/insertion/cyclization/elimination reaction sequence, phenanthridines are successfully constructed, providing an attractive strategy to approach substituted heterocycle without preactivation of starting materials.     

A simple and economic method for accurate determination of the energy peak efficiency of 208 keV γ-ray of 237U based on 241Pu/237U secular equilibrium

A new method is developed for the determination of energy peak efficiency of 208 keV γ-ray of ²³⁷U based on ²⁴¹Pu/²³⁷U secular equilibrium. Plutonium solution was purified to remove Am with Dowex 1 × 2 anion exchange chromatography and the concentration of ²⁴¹Pu in the purified solution was determined using ²⁴²Pu isotope-dilution mass spectrometry on an inductively-coupled plasma mass spectrometry. The solution can be used as calibration source for the determination of energy peak efficiency of 208 keV γ-ray of ²³⁷U after 48 days. The method was validated for a planar HPGe detector at the 12 mm above the detector surface. The results showed that this is a simple and economic method for determining the energy peak efficiency of gamma detectors for 208 keV γ-ray of ²³⁷U.     

Ethanol synthesis from syngas on Mn- and Fe-promoted Rh/γ-Al2O3

The catalytic hydrogenation of CO was studied over Mn- and/or Fe-promoted Rh/γ-Al₂O₃ catalysts. The catalysts were characterized by means of XRD, BET, H₂-TPR·H₂-TPD, XPS and DRIFTS. CO hydrogenation results showed that the doubly Mn- and Fe-promoted Rh/γ-Al₂O₃ catalysts exhibited superior catalytic activity and better ethanol selectivity. The DRIFTS results showed that Mn promoter stabilized the adsorbed CO on Rh⁺ and Fe stabilized adsorbed CO on Rh⁺ and Rh⁰, especially Rh⁰. The fact that doubly Mn- and Fe-promoted Rh/γ-Al₂O₃ owned more (Rhx⁰–Rhy⁺)–O–Fe³⁺·(Fe²⁺) active species was proposed to be a crucial factor accounting for its higher ethanol selectivity.     

Thermoresponsive AuNPs Stabilized by Pillararene‐Containing Polymers

Pillararene‐containing thermoresponsive polymers are synthesized via reversible addition–fragmentation chain transfer polymerization using pillararene derivatives as the effective chain transfer agents for the first time. These polymers can self‐assemble into micelles and form vesicles after guest molecules are added. Furthermore, such functional polymers can be further applied to prepare hybrid gold nanoparticles, which integrate the thermoresponsivity of polymers and molecular recognition of pillararenes.

     

钯合金膜分离纯化氢同位素的研究进展

钯合金膜因其具有优异的透氢性能及良好的化学和热稳定性,已被广泛应用于氢同位素的分离纯化领域。而PdAg和PdY合金膜在众多钯合金膜中透氢性能出色备受关注。本文比较了PdAg、PdY等多元钯合金膜的透氢性能及抗中毒情况,总结了PdAg复合膜的制备方法及透氢选择性,重点介绍了钯合金膜分离氢同位素的研究进展,并对钯合金膜的未来研究方向进行展望。     

Cu Doping-Induced Transformation from [Ag62S12(SBut)32]2+ to [Ag62−xCuxS12(SBut)32]4+ Nanocluster

The change in the valence state of nanocluster can induce remarkable changes in the properties and structure. However, achieving the valence state changes in nanoclusters is still a challenge. In this work, we use Cu²⁺ as dopant to “oxidize” [Ag₆₂S₁₂(SBu^t)₃₂]²⁺ (4 free electrons) to obtain the new nanocluster: [Ag_62−xCu_xS₁₂(SBu^t)₃₂]⁴⁺ with 2 free electrons. As revealed by its structure, the [Ag_62−xCu_xS₁₂(SBu^t)₃₂]⁴⁺ (x=10∼21) has a similar structure to that of [Ag₆₂S₁₂(SBu^t)₃₂]²⁺ precursor and all the Cu atoms occupy the surface site of nanocluster. It′s worth noting that with the Cu atoms doping, the [Ag_62−xCu_xS₁₂(SBu^t)₃₂]⁴⁺ nanocluster is more stable than [Ag₆₂S₁₂(SBu^t)₃₂]²⁺ at higher temperature and in electrochemical cycle. This result has laid a foundation for the subsequent application and exploration. Overall, this work reveals crystals structure of a new Ag−Cu nanocluster and offers a new insight into the electron reduction/oxidation of nanocluster.     

锂离子电池硅氧化物负极首次库伦效率的影响因素与提升策略

硅氧化物(SiO_x, 0<x≤2)具有高的比容量和低的嵌锂电位, 且体积膨胀率显著低于纯硅负极, 因而被认为是替代传统石墨负极材料的理想选择之一. 然而SiO_x负极在首次嵌锂过程中表面形成的固体电解质界面膜(SEI)以及大量的不可逆产物, 造成其首次库伦效率偏低, 严重阻碍了SiO_x负极的实际应用. 本文从SiO_x的结构模型出发, 系统阐述了SiO_x负极的嵌锂机理以及首次库伦效率低的原因; 归纳了SiO_x负极首次库伦效率的提升策略及其研究进展; 并对提升SiO_x负极首次库伦效率的未来发展方向进行了展望.