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1.
建立了碰撞池-电感耦合等离子体质谱法测定芝麻中痕量的锗元素(germanium , Ge)。采用微波消解,碰撞池(KED模式)-电感耦合等离子体质谱检测,在线引入内标元素铑(Rh),同时消解液中加入3%正戊醇增敏。结果 3 % 正戊醇可使74Ge的上机检测信号强度提高2.85倍,74Ge校正曲线线性相关系数为1.00000,检出限为0.0555 μg/kg,加标回收率为92.0%~106%,相对标准偏差(relative standard deviation, RSD%)为2.6%~4.3%。采用建立的方法测定7种国家标准物质,检测结果均在认定值范围内,RSD%为2.5%~8.8%。结论 该方法灵敏度高、准确,可实现批量检测,适用于芝麻中痕量锗的检测。  相似文献   
2.
Meropenem, a representative β-lactam antibiotic, is widely used to treat complicated and serious infections. Therefore, it is of great significance to monitor the plasma drug concentration for individualized antimicrobial therapy. This study first describes the development and validation of high-performance liquid chromatography–tandem mass spectrometry cubed method for monitoring meropenem in human plasma. Protein precipitation with methanol and a chromatographic analysis time of 7 min make this method simple and of high throughput. Meropenem was extracted from human plasma with recoveries >94.1%. Calibration curves were linear (R> 0.995) in the concentration range of 0.5–50 μg/mL. Overall accuracy and precision did not exceed 8.0% as well as no significant matrix effect was observed. The novelty of this method is that the triple-stage mass spectrometry technology improves the selectivity and sensitivity. A comparison of the presented method and traditional liquid chromatography–tandem mass spectrometry method was assessed in 44 patients treated with meropenem and Passing–Bablok regression coefficients and Bland–Altman plots showed that no significant difference between the two methods. So the triple-stage mass spectrometry method developed in this study is appropriate and practical for the monitor of meropenem in the daily clinical laboratory practice.  相似文献   
3.
Li  Yuhan  An  Hongli  Zhang  Yiyuan 《Nonlinear dynamics》2022,108(3):2489-2503
Nonlinear Dynamics - Fission and fusion are important phenomena, which have been observed experimentally in many physical areas. In this paper, we study the above two phenomena in the ( $$2+1$$...  相似文献   
4.
Journal of Theoretical Probability - We prove a functional limit theorem for vector-valued functionals of the fractional Ornstein–Uhlenbeck process, providing the foundation for the...  相似文献   
5.
The reaction of N2 with trinuclear niobium and tungsten sulfide clusters Nb3Sn and W3Sn (n=0–3) was systematically studied by density functional theory calculations with TPSS functional and Def2-TZVP basis sets. Dissociations of N−N bonds on these clusters are all thermodynamically allowed but with different reactivity in kinetics. The reactivity of Nb3Sn is generally higher than that of W3Sn. In the favorite reaction pathways, the adsorbed N2 changes the adsorption sites from one metal atom to the bridge site of two metal atoms, then on the hollow site of three metal atoms, and at that place, the N−N bond dissociates. As the number of ligand S atoms increases, the reactivity of Nb3Sn decreases because of the hindering effect of S atoms, while W3S and W3S2 have the highest reactivity among four W3Sn clusters. The Mayer bond order, bond length, vibrational frequency, and electronic charges of the adsorbed N2 are analyzed along the reaction pathways to show the activation process of the N−N bond in reactions. The charge transfer from the clusters to the N2 antibonding orbitals plays an essential role in N−N bond activation, which is more significant in Nb3Sn than in W3Sn, leading to the higher reactivity of Nb3Sn. The reaction mechanisms found in this work may provide important theoretical guidance for the further rational design of related catalytic systems for nitrogen reduction reactions (NRR).  相似文献   
6.
Efficient,robust and cost-effective electrocatalysts that catalyze hydrogen evolution/oxidation reaction(HER/HOR)in alkaline media are highly demanded.Recently,single-atom catalysts(SACs)have emerged as new promising candidates;however,the rational design of supports and the optimization of coordination environment between supports and metal atoms are challenging.In this work,we successfully fabricate atomically dispersed ruthenium(Ru)species,which are strongly coordinated by N and S dual heteroatoms on holey graphene(RuSA/NSG),as an excellent bifunctional catalyst for HER/HOR.In alkaline media,the developed catalyst exhibits high catalytic performance with a low overpotential of 57.3 mV to drive a current density of 10 mA cm-1 for HER,and its mass activity is about 5.8 times higher than that of commercial Pt/C and Ru/C catalysts at an overpotential of 100 mV.Similarly,considerable HOR performance of Ru SA/NSG is verified to be superior to Pt/C and Ru/C.Furthermore,X-ray-based spectroscopy measurements and density-functional theory calculations have confirmed that,compared with Ru–N4,the tailored Ru–N4–S2 with nearby S dopants can act as more active centers to greatly accelerate the sluggish HER/HOR kinetics in alkaline media.The present work provides a new atomic-level engineering strategy to modulate catalytic activities of SACs via the coordination design using dual heteroatoms on the carbon support.  相似文献   
7.
The rational designability and chemical tunability of metal-organic frameworks(MOFs)are enabling tributes to efficaciously enhance their room temperature phosphorescence(RTP)performance.A family of stable anionic MOFs,[Zn2(4,5-ImDC)2]M2(NKU-132,M=(CH3)2NH2or(CH2CH3)2NH2),featuring significant RTP have been synthesized.By rational cation selection and in-situ replacement from dimethylammonium to diethylammonium,the phosphorescence lifetime is increased from 30.88 to126.3 ms,along with less sensitivity to air.This work provides an anti-quenching and lifetime tuning example for RTP-MOFmaterials via facile host-guest chemistry.  相似文献   
8.
9.
Li  Zh.  Zhang  Y.  Wang  R.  Jiang  D. 《Journal of Applied Spectroscopy》2022,89(2):371-380
Journal of Applied Spectroscopy - The concentration of heavy metals in drinking water is an important standard for water quality evaluation and water pipeline corrosion detection. This research...  相似文献   
10.
The observation and study of nonlinear dynamical systems has been gaining popularity over years in different fields. The intrinsic complexity of their dynamics defies many existing tools based on individual orbits, while the Koopman operator governs evolution of functions defined in phase space and is thus focused on ensembles of orbits, which provides an alternative approach to investigate global features of system dynamics prescribed by spectral properties of the operator. However, it is difficult to identify and represent the most relevant eigenfunctions in practice. Here, combined with the Koopman analysis, a neural network is designed to achieve the reconstruction and evolution of complex dynamical systems. By invoking the error minimization, a fundamental set of Koopman eigenfunctions are derived, which may reproduce the input dynamics through a nonlinear transformation provided by the neural network. The corresponding eigenvalues are also directly extracted by the specific evolutionary structure built in.  相似文献   
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