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VON SZENTPáLY László 《物理化学学报》2018,34(6):675-682
The addition of electrons to form gas-phase multiply charged anions (MCAs) normally requires sophisticated experiments or calculations.In this work, the factors stabilizing the MCAs, the maximum electron uptake of gas-phase molecules, X, and the electronic stability of MCAs XQ-, are discussed. The drawbacks encountered when applying computational and/or conceptual density functional theory (DFT) to MCAs are highlighted. We develop and test a different model based on the valence-state concept. As in DFT, the electronic energy, E(N, vex), is a continuous function of the average electron number, N, and the external potential, vex, of the nuclei. The valence-state-parabola is a second-order polynomial that allows extending E(N, vex) to dianions and higher MCAs. The model expresses the maximum electron acceptance, Qmax, and the higher electron affinities, AQ, as simple functions of the first electron affinity, A1, and the ionization energy, I, of the "ancestor" system. Thus, the maximum electron acceptance is Qmax, calc = 1 + 12A1/7(I -A1). The ground-state parabola model of the conceptual DFT yields approximately half of this value, and it is termed Qmax, GS = ${}^{1}\!\!\diagup\!\!{}_{2}\; $ + A1/(I -A1). A large variety of molecules are evaluated including fullerenes, metal clusters, super-pnictogens, super-halogens (OF3), super-alkali species (OLi3), and neutral or charged transition-metal complexes, ABmLn0/+/-. The calculated second electron affinity A2, calc = A1-(7/12)(I -A1) is linearly correlated to the literature references A2, lit with a correlation coefficient R = 0.998. A2 or A3 values are predicted for further 24 species. The appearance sizes, nap3-, of triply charged anionic clusters and fullerenes are calculated in agreement with the literature. 相似文献
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Bateman RJ Munsell LY Chen X Holtzman DM Yarasheski KE 《Journal of the American Society for Mass Spectrometry》2007,18(6):997-1006
In all biological systems, protein amount is a function of the rate of production and clearance. The speed of a response to a disturbance in protein homeostasis is determined by turnover rate. Quantifying alterations in protein synthesis and clearance rates is vital to understanding disease pathogenesis (e.g., aging, inflammation). No methods currently exist for quantifying production and clearance rates of low-abundance (femtomole) proteins in vivo. We describe a novel, mass spectrometry-based method for quantitating low-abundance protein synthesis and clearance rates in vitro and in vivo in animals and humans. The utility of this method is demonstrated with amyloid-beta (Abeta), an important low-abundance protein involved in Alzheimer's disease pathogenesis. We used in vivo stable isotope labeling, immunoprecipitation of Abeta from cerebrospinal fluid, and quantitative liquid chromatography electrospray-ionization tandem mass spectrometry (LC-ESI-tandem MS) to quantify human Abeta protein production and clearance rates. The method is sensitive and specific for stable isotope-labeled amino acid incorporation into CNS Abeta (+/-1% accuracy). This in vivo method can be used to identify pathophysiologic changes in protein metabolism and may serve as a biomarker for monitoring disease risk, progression, or response to novel therapeutic agents. The technique is adaptable to other macromolecules, such as carbohydrates or lipids. 相似文献
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Minh-Phuong TRAN Thanh-Nhan NGUYEN Phuoc-Toan HUYNH Nhu-Binh LY Minh-Dang NGUYEN Quoc-Anh HO 《数学物理学报(B辑英文版)》2022,(1):105-126
In this paper,we establish a new algorithm to the non-overlapping Schwarz domain decomposition methods with changing transmission conditions for solving one dimensional advection reaction diffusion problem.More precisely,we first describe the new algorithm and prove the convergence results under several natural assumptions on the sequences of parameters which determine the transmission conditions.Then we give a simple method to estimate the new value of parameters in each iteration.The interesti... 相似文献
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