Extraction of Uranium in Nitric Media with Novel Asymmetric Tetra-Alkylcarbamide

The use of tetra-alkylcarbamides as novel ligands: N,N-butyl-N’,N’-hexylurea (L1: ABHU), and N,N-butyl-N’,N’-pentylurea (L2: ABPU), for the solvent extraction and complexation behaviors of uranium(VI) was synthesized and investigated in this study. The effects of HNO₃ and NO₃⁻ concentrations in the aqueous phase on the distribution ratio of U(VI) were examined. Under 5 mol/L HNO₃ concentration, D_U reached 5.02 and 4.94 respectively without third-phase formation. During the extraction, slope measurements and IR spectral analysis revealed that the U(VI) complexes are a form of UO₂(NO₃)₂·2L for both ligands. In addition, thermodynamic studies showed that the uranium extraction reaction was a spontaneous exothermic reaction. The deep structural analysis of the complexes was realized with DFT calculation. The bond length, bond properties, and topology of the complexes were discussed in detail to analyze the extraction behavior. This study enriches the coordination chemistry of U(VI) by tetra-alkylcarbamides, which may offer new clues for the design and synthesis of novel ligands for the separation, enrichment, and recovery of uranium in the nuclear fuel cycle.     

Robust Laminated Anode with an Ultrathin Titanium Nitride Layer for High-Efficiency Top-Emitting Organic Light-Emitting Diodes

The effective reflective anode remains a highly desirable component for the fabrication of reliable top-emitting organic light-emitting diodes (TE-OLEDs) which have the potential to be integrated with complementary metal-oxide-semiconductor (CMOS) circuits for microdisplays. This work demonstrates a novel laminated anode consisting of a Cr/Al/Cr multilayer stack. Furthermore, we implement an ultra-thin titanium nitride (TiN) layer as a protective layer on the top of the Cr/Al/Cr composite anode, which creates a considerably reflective surface in the visible range, and meanwhile improves the chemical stability of the electrode against the atmosphere or alkali environment. Based on [2-(2-pyridinyl-N)phenyl-C](acetylacetonate)iridium(III) as green emitter and Mg/Ag as transparent cathode, our TE-OLED using the TiN-coated anode achieves the maximum current efficiency of 71.2 cd/A and the maximum power efficiency of 66.7 lm/W, which are 81% and 90% higher than those of the reference device without TiN, respectively. The good device performance shows that the Cr/Al/Cr/TiN could function as a promising reflective anode for the high-resolution microdisplays on CMOS circuits.     

Locally periodically poled LNOI ridge waveguide for second harmonic generation

Periodically poled lithium niobate on insulator[LNOI]ridge waveguides are desirable for high-efficiency nonlinear frequency conversions,and the fabrication proc...     

Atmospheric CO_2 capture and photofixation to near-unity CO by Ti~(3+)-V_o-Ti~(3+) sites confined in TiO_2 ultrathin layers

To realize efficient atmospheric CO_2 chemisorption and activation,abundant Ti~(3+) sites and oxygen vacancies in TiO_2 ultrathin layers were designed.Positron annihilation lifetime spectroscopy and theoretical calculations first unveil each oxygen vacancy is associated with the formation of two Ti~(3+) sites,giving a Ti~(3+)-V_o-Ti~(3+)configuration.The Ti~(3+)-V_o-Ti~(3+) sites could bond with CO_2 molecules to form a stable configuration,which converted the endoergic chemisorption step to an exoergic process,verified by in-situ Fourier-transform infrared spectra and theoretical calculations.Also,the adjacent Ti~(3+) sites not only favor CO_2 activation into COOH*via forming a stable Ti~(3+)–C–O–Ti~(3+) configuration,but also facilitate the rate-limiting COOH~* scission to CO~* by reducing the energy barrier from 0.75 to 0.45 e V.Thus,the Ti~(3+)-V_o-TiO_2 ultrathinlayers could directly capture and photofix atmospheric CO_2 into near-unity CO,with the corresponding CO_2-to-CO conversion ratio of ca. 20.2%.     

论自我知识的构成主义观点

构成主义观点致力于在自然主义的心灵图景中解释自我知识的特殊性与第一人称权威。为此,它主张高阶信念和一阶态度不是相互独立的,而是有着构成性的关系。概念论解释试图从认识主体的概念能力,特别是批判性推理的能力来作出论证。默认权威观点则诉诸日常话语实践的“语法”要求,主张认识主体对自我的态度拥有先天合理的、又可由证据挫败的确信。通过引入“以言行事”的思路,构成主义有希望确立起合理、审慎、有节制的第一人称权威观点。     

Thermodynamic Resolution of Pharmaceutical Precursor Modafinil Acid on the Basis of Chiral-at-Metal Strategy

Main observation and conclusion Chiral-at-metal strategy was developed to resolve the essential sulfoxide pharmaceutical intermediates R-modafinil acid and its ...     

Versatile Graphene-Isolated AuAg-Nanocrystal for Multiphase Analysis and Multimodal Cellular Raman Imaging

Main observation and conclusion Surface-enhanced Raman spectroscopy(SERS)-based bioanalytical technique involves the interaction of SERS-active substrate with c...     

FAIR收集环二极超导磁体外杜瓦泄放系统的概念设计

对FAIR(Facility for Antiproton and Ion Research)收集环-CR(Collector Ring)二极超导磁体外杜瓦的超压泄放系统进行了概念设计,给出了爆破片式的泄放系统结构,并基于ANSYS的结构分析初步确定了爆破片的结构参数;以及通过ANSYS对波纹管和外杜瓦进行了结构分析,分析结果表明波纹管和外杜瓦在超压状态下安全。文中的设计和分析研究,为外杜瓦的工程设计提供了有益的参考。     

在无单元法里直接准确施加位移边界条件和材料不连续条件

在无单元伽辽金法(EFG)里,由于其滑动最小二乘近似位移函数不满足Kronecker条件,使得它不能准确地施加本质边界条件和材料不连续条件,从而极大地限制了EFG法的发展和进一步应用。本文在位移边界和不同材料交界面的离散结点上采用实际的结点位移值,提出了一种准确施加位移边界和材料不连续条件的方法,该方法实施简单、稳定、求解精度高,而且其推导得出的整体刚度矩阵具有正定、对称和带状分布的特点,可以和有限单元法一样,直接利用各种成熟、高效的线性方程组解法求解系统平衡方程。数值算例结果表明了文中理论和方法的正确性和可靠性。