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101.
以硝酸铕、2-(4-氟代苯甲酰基)苯甲酸(HL)、1,10-菲咯啉(Phen)和三苯基氧膦(TPPO)合成了EuL3(H2O)6,EuL3Phen(H2O)4和EuL3(TPPO)(H2O)5三种固态配合物。用元素分析、红外光谱、核磁共振氢谱对配合物进行了组分确定和结构表征。IR表明,2-(4-氟代苯甲酰基)苯甲酸与Eu3+形成配合物后,位于1 692 cm-1处羧基的νCO峰消失,2 500~3 200 cm-1处羧基的νO—H峰也消失,出现了羧酸盐特有的反对称伸缩振动吸收峰(νas(CO-2))和对称伸缩振动吸收峰(νs(CO-2)),且Δν(νas(CO-2)-νs(CO-2))与钠盐的Δν相近,说明羧酸根与Eu3+以对称双齿桥式配位。在1H NMR中,形成配合物后第一配体苯环上的质子峰变为宽峰且移向高场,Phen和TPPO中质子化学位移移向低场。室温下测定了配合物的荧光激发光谱和发射光谱,激发光谱表明配合物EuL3(H2O)6,EuL3Phen(H2O)4和EuL3(TPPO)(H2O)5的最佳激发波长分别为353.0,355.0和357.0 nm;发射光谱均显示Eu3+离子的特征发射光谱,且表明Phen对Eu3+离子的荧光发射有明显增强作用。 相似文献
102.
Mourad Benlamri Kyle M. Bothe Alex M. Ma Gem Shoute Amir Afshar Himani Sharma Arash Mohammadpour Manisha Gupta Kenneth C. Cadien Ying Y. Tsui Karthik Shankar Douglas W. Barlage 《固体物理学:研究快报》2014,8(10):871-875
A high effective electron mobility of 33 cm2 V–1 s–1 was achieved in solution‐processed undoped zinc oxide (ZnO) thin films. The introduction of silicon nitride (Si3N4) as growth substrate resulted in a mobility improvement by a factor of 2.5 with respect to the commonly used silicon oxide (SiO2). The solution‐processed ZnO thin films grown on Si3N4, prepared by low‐pressure chemical vapor deposition, revealed bigger grain sizes, lower strain and better crystalline quality in comparison to the films grown on thermal SiO2. These results show that the nucleation and growth mechanisms of solution‐processed films are substrate dependent and affect the final film structure accordingly. The substantial difference in electron mobilities suggests that, in addition to the grain morphology and crystalline structure effects, defect chemistry is a contributing factor that also depends on the particular substrate. In this respect, interface trap densities measured in high‐κ HfO2/ZnO MOSCAPs were about ten times lower in those fabricated on Si3N4 substrates. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)
103.
This study described palladium-catalyzed chemoselective direct α-arylation of carbonyl compounds with chloroaryl triflates in the Ar–Cl bond. The Pd/SelectPhos system showed excellent chemoselectivity toward the Ar–Cl bond in the presence of the Ar–OTf bond with a broad substrate scope and excellent product yields. The electronic and steric hindrance offered by the –PR2 group of the ligand with the C2-alkyl group was found to be the key factor affecting the reactivity and chemoselectivity of the α-arylation reaction. The chemodivergent approach was also successfully employed in the synthesis of flurbiprofen and its derivatives (e.g., –OMe and –F).Palladium-catalyzed chemoselective direct α-arylation of carbonyl compounds with chloroaryl triflates in the Ar–Cl bond is reported. The effects of –PR2 and C2-alkyl groups of the ligands are investigated using experimental and computational methods. 相似文献
104.
We extend an optimal entanglement distillation of the triplet Greenberger-Horne-Zeilinger (GHZ) state via entanglement concentrating in the three-partite partially electron-spin-entangled systems. Two entanglement concen- tration protocols are similarly designed in detail with the post-selection in quantum-dot (QD) and micro-cavity coupled systems. The proposed protocol can be repeated several rounds to achieve an optimal success probability with an as- sistance of the ancillary QD, where only the single photon needs to pass through the micro-cavity for each round. It increases the total success probability of the distillation even if the implemented cavity is imperfect in practice during the whole process. 相似文献
105.
Measurement of Diffusion Coefficient of Liquids by Using an Asymmetric Liquid-Core Cylindrical Lens: Observing the Diffusion Process Directly 下载免费PDF全文
We report a method for measuring diffusion coefficient D of liquids by using an aplanatic and asymmetric cylinder lens with a liquid core, which is designed as both a diffusion pool and the main imaging element. The precision is better than 10-4 RIU in measuring refractive index. The D values of ethylene glycol (EG) in water are measured for various EG concentrations at 25℃, and Dinf = 1.043 × 10^-5 cm^2/s under the condition of infinite dilution is obtained. The method is characterized by observing the diffusion process directly, faster measurement and obtaining the D value under the condition of infinite dilution. 相似文献
106.
电催化剂固氮能够在温和条件下催化氮气还原制氨.本工作基于第一性原理计算,系统地探究了分散在二维V2CN2上过渡金属二聚体(Fe, Mo, Ru)形成的双原子催化剂用于电催化固氮的可行性.双原子的协同作用使氮气得到较好的活化.吉布斯自由能计算表明,在V2CN2负载双铁原子(Fe2@V2CN2)体系进行的催化反应过电位最低,仅为0.25 eV.进一步的分子动力学计算表明Fe2@V2CN2具有较好的结构稳定性,并且该体系能很好的抑制HER反应的发生.通过与Mo2@V2CN2,Ru2@V2CN2体系的比较可知,氮气分子的吸附构型以及HER反应的竞争对催化剂的选择影响很大.我们的计算能够为双原子催化剂的设计提供更多的依据. 相似文献
107.
108.
Xinyi Liu Ying Tang Weiyu Ning Yihong Bao Ting Luo Jinling Wang 《Molecules (Basel, Switzerland)》2022,27(9)
This study aimed to elucidate the responses of a novel characterized Issatchenkia terricola WJL-G4 against citric acid stress by performing physiological analysis, morphology observation, and structural and membrane fatty acid composition analysis. The results showed that under citric acid stress, the cell vitality of I. terricola WJL-G4 was reduced. The cell morphology changed with the unclear, uncompleted and thinner cell wall, and degraded the cell structure. When the citric acid concentration was 20 g/L, I. terricola WJL-G4 could tolerate citric acid and maintain the cell structure by increasing the intracellular pH, superoxide dismutase activity, and contents of unsaturated fatty acids. As the citric acid concentration was ≥80 g/L, the stress has exceeded the cellular anti-stress ability, causing substantial cell damage. The cell membrane permeability, the content of membrane lipids, malondialdehyde and superoxide anion increased, but the intracellular pH and superoxide dismutase activities decreased, accompanying the increase of citric acid concentrations. The findings of this work provided a theoretical basis for the responsive mechanism of I. terricola WJL-G4 under high concentrations of citric acid, and can serve as a reference for biological acid reduction in fruit processing. 相似文献
109.
利用分子轨道从头算理论和密度泛函理论结合不同理论基组对于N-H…O蓝移氢键进行了详细的研究.利用标准方法和均衡校正方法对二聚体进行了几何优化,振动频率和相互作用能的计算.拓扑学和自然键轨道理论对于蓝移氢键的本质进行分析.自然键轨道(NBO)分析表明,σ*(N-H)轨道上电子密度降低是电子密度重排效应的结果.分子内电子重排、轨道再杂化和电子受体内部结构重组共同作用结果导致了N-H的振动频率大幅蓝移现象的出现. 相似文献
110.
Effect of Reactor Pressure on Qualities of GaN Layers Grown by Hydride Vapour Phase Epitaxy 下载免费PDF全文
The influence of reactor pressure on GaN layers grown by hydride vapour phase epitaxy (HVPE) is investigated. By decreasing the reactor pressure from0. 7 to 0.5 mm, the GaN layer growth mode changes from the island-like one to the step flow. The improvements in structural and optical properties and surface morphology of GaN layers are observed in the step flow growth mode. The results clearly indicate that the reactor pressure, similarly to the growth temperature, is One of the important parameters to influence the qualities of GaN epilayers grown by HVPE, due to the change of growth mode. 相似文献