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排序方式: 共有236条查询结果,搜索用时 15 毫秒
1.
A heavy crude oil has been treated with deuterated alkylating reagents (CD3I and C2D5I) and directly analyzed without any prior fractionation and chromatographic separation by high-field Orbitrap Fourier Transform Mass Spectrometry (FTMS) and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) using electrospray ionization (ESI). The reaction of a polycyclic aromatic sulfur heterocycles (PASHs) dibenzothiophene (DBT), in the presence of silver tetrafluoroborate (AgBF4) with ethyl iodide (C2H5I) in anhydrous dichloroethane (DCE) was optimized as a sample reaction to study heavy crude oil mixtures, and the reaction yield was monitored and determined by proton nuclear magnetic resonance spectroscopy (1H-NMR). The obtained conditions were then applied to a mixture of standard aromatic CH-, N-, O- and S-containing compounds and then a heavy crude oil, and only sulfur-containing compounds were selectively alkylated. The deuterium labeled alkylating reagents, iodomethane-d3 (CD3I) and iodoethane-d5 (C2D5I), were employed to the alkylation of heavy crude oil to selectively differentiate the tagged sulfur species from the original crude oil. 相似文献
2.
液相催化交换法是有效的氢同位素分离方法之一,传统电解法进行氘重氧水氢正常化安全风险大,生产成本高,为此利用液相催化交换法对含氘重氧水进行除氘实验。结果表明,反应温度在30~70 ℃内,随着温度升高,含氘重氧水除氘过程的总体积传质系数(Kya)值先变大后变小,当温度大于60 ℃后,总体积传质系数Kya值逐渐变小,最优反应温度为60 ℃;气液比(摩尔比)在0.5~3.0之间,随着气液比增加,含氘重氧水除氘过程的Kya值愈大,含氘重氧水除氘效果越好,但过大的气液比会引起气液夹带甚至导致液泛,降低反应效率。实验结果可为开展高氘浓度氘重氧水液相催化交换法氢正常化工艺研究提供依据。 相似文献
3.
Ankur Solanki Mohammad Mahdi Tavakoli Qiang Xu Sai S. H. Dintakurti Swee Sien Lim Anirban Bagui John V. Hanna Jing Kong Tze Chien Sum 《Advanced materials (Deerfield Beach, Fla.)》2020,32(23):1907864
Heavy water or deuterium oxide (D2O) comprises deuterium, a hydrogen isotope twice the mass of hydrogen. Contrary to the disadvantages of deuterated perovskites, such as shorter recombination lifetimes and lower/invariant efficiencies, the serendipitous effect of D2O as a beneficial solvent additive for enhancing the power conversion efficiency (PCE) of triple-A cation (cesium (Cs)/methylammonium (MA)/formaminidium (FA)) perovskite solar cells from ≈19.2% (reference) to 20.8% (using 1 vol% D2O) with higher stability is reported. Ultrafast optical spectroscopy confirms passivation of trap states, increased carrier recombination lifetimes, and enhanced charge carrier diffusion lengths in the deuterated samples. Fourier transform infrared spectroscopy and solid-state NMR spectroscopy validate the N–H2 group as the preferential isotope exchange site. Furthermore, the NMR results reveal the induced alteration of the FA to MA ratio due to deuteration causes a widespread alteration to several dynamic processes that influence the photophysical properties. First-principles density functional theory calculations reveal a decrease in PbI6 phonon frequencies in the deuterated perovskite lattice. This stabilizes the PbI6 structures and weakens the electron–LO phonon (Fröhlich) coupling, yielding higher electron mobility. Importantly, these findings demonstrate that selective isotope exchange potentially opens new opportunities for tuning perovskite optoelectronic properties. 相似文献
4.
利用高能离子注入机和直线等离子体模拟装置,本文研究了高能氦离子预注入对氘等离子体辐照后钨中氘滞留行为的影响。采用FIB-SEM、TEM、GD-OES和TDS等分析方法,分析了氦离子预注入对钨中氘滞留行为的影响。结果表明:氦离子预注入在辐照损伤区域形成大量氦泡,钨经过氘等离子体辐照后,表面的氘泡数量明显低于未经过氦离子预注入的样品。GD-OES分析中可以看到在氦捕获位处氘滞留浓度明显升高,同时氦离子预注入增加了氘在钨中的扩散深度,结合TDS分析可知氦离子预注入增加了氘在钨中的滞留总量,这是由于氦离子预注入后,形成的缺陷又为钨中氘的俘获提供大量新的位点,从而导致钨中的氘滞留量明显提高。 相似文献
5.
Dr. Carsten Kegler Friederike I. Nollmann Tilman Ahrendt Florian Fleischhacker Edna Bode Prof. Dr. Helge B. Bode 《Chembiochem : a European journal of chemical biology》2014,15(6):826-828
An E. coli strain with deletions in five transaminases (ΔaspC ΔilvE ΔtyrB ΔavtA ΔybfQ) was constructed to be unable to degrade several amino acids. This strain was used as an expression host for the analysis of the amino acid configuration of nonribosomally synthesized peptides, including the novel peptide “xenotetrapeptide” from Xenorhabdus nematophila, by using a combination of labeling experiments and mass spectrometry. Additionally, the number of D ‐amino acids in the produced peptide was assigned following simple cultivation of the expression strain in D2O. 相似文献
6.
《Fusion Engineering and Design》2014,89(11):2666-2671
The development of safe, efficient, and cost effective methods to recover waste components of deuterium–tritium (D–T) plasma reactors, including hydrogen and methane, has attracted much interest in the scientific community. Typically, membrane separators are used for this process, although several problems occur when performing separations at higher temperatures. The application of noble metal catalysts may improve the reaction dynamics and allow the separation process to occur at lower temperatures. In this paper, a series of noble metal catalysts were prepared by a traditional dipping method. Based on an analysis of catalytic performance, the Rh/Al2O3 catalyst was determined to be the most suitable for the exchange of hydrogen and deuterium in methane. The catalyst was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and temperature programmed reduction analyses. The effects of the metal loading and experimental conditions were also investigated. 相似文献
7.
氢同位素在材料中的扩散、捕获和滞留等行为可通过热脱附谱实验方法进行研究。为实现对同时含有氘氦的钨材料进行热脱附测量并研究钨中氘氦滞留行为,搭建了1套基于高分辨四极质谱仪的热脱附实验系统HiTDS。HiTDS实现了1.2×10-6 Pa的高本底真空度,速率为1 K/s的精确线性升温,最高加热温度达1423 K,能准确测量样品中气体元素的脱附速率和脱附量。通过配备高分辨四极质谱仪,HiTDS可快速分辨氘氦元素并测量其脱附速率。HiTDS经过调谐校准、标定系数标定后,对氘氦等离子体辐照钨样品进行了热脱附测量。测得的氘氦热脱附谱显示,纯氘脱附量与剂量正相关,而氦的引入显著抑制氘滞留并使其趋于饱和。热脱附实验结果与类似辐照条件的其他研究成果基本一致,检验了该实验方法的有效性。 相似文献
8.
9.
利用色谱分离的速率理论分析了贮氚老化影响钯氢化物中恒流速氢氘交换性能的原因,并利用塔板理论模拟了氢氘交换流出曲线,同时,实验对比了未贮氚老化与贮氚老化1.6年钯的氢氘交换流出曲线。理论模拟结果表明:贮氚老化后,钯氢化物氢氘交换反应的塔板数n减少,塔板高度H增加,交换反应的平衡时间增长,氢氘交换流出曲线趋于平缓,氢氘交换性能下降。而塔板高度的增加,是由于衰变3He滞留在钯材料中,导致氢同位素在老化钯中的扩散受阻,同时使得钯的氢同位素分离因子改变。实验对比结果表明:恒流速状态下,贮氚老化1.6年钯的氢氘交换流出曲线较之未贮氚老化钯变得平缓,氢氘交换性能下降。理论模拟与实验结果符合较好。 相似文献
10.
材料问题是可控核聚变能否实现商业应用从而解决人类能源问题的"瓶颈"之一。低活化铁素体/马氏体(RAFM)钢具有良好的抗辐照性能,被普遍认为是新一代聚变反应堆的候选结构材料之一。在聚变堆环境下,材料不仅会受到高能中子辐照而且氘氚也可能进入材料中。为了研究氘离子以及辐照对低活化钢的微观结构的影响,采用CLAM钢(一种RAFM钢)和FeCr模型合金,在500℃下进行58keV氘离子辐照,利用高分辨透射电镜对比分析辐照前后材料微观结构的变化,研究辐照及氘离子对低活化钢的影响。结果表明:高温氘离子辐照不仅在材料中产生大量的缺陷和缺陷集团,同时还可能产生辐照诱导析出。而CLAM钢中原有的析出物经高温离子辐照后并没有发生非晶化,对其原因进行了讨论。 相似文献