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81.
K. Wagner R. Lenz H. Gaedike Regina Müller W. Joachim 《Isotopes in environmental and health studies》2013,49(9-10):338-341
Es werden die Ergebnisse von Mischverfahren für Kohlepulver, Pech und andere Komponenten mitgeteilt, die unter Markierungen mit 24Na-Benzoat im Laboratorium (Mischvolumen etwa 1 Liter) und im Betrieb (Mischvolumen etwa 100 Liter) durchgführt wurden. Die Experimente dienten dem Vergleich der Vergleich der Wirksamkeit verschiedener Mischmaschinen, der Ermittlung optimaler Mischzeiten und der Bestimmung des Verhaltens einzelner Komponenten beim Mischprozeβ. Dis mittels Szintillationszählung gewonnenen Meβwerte werden dabei mit einem Ergebnisdrucker registriert und mit Hilfa einer Rechenanlage mathematisch ausfewertet. 相似文献
82.
Enhancement of green emission by the codoping U . 3+ A+ (A - Li, Na, K) in Ca2 O3CI.Tb phosphor
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Tb3+-doped Ca2BO3C1 compounds with different charge compensation approaches are synthesized by a hightemperature solid-state reaction method, and the luminescent properties and Commission Internationale de l'Eclairage (CIE) chromaticity coordinates are systematically characterized. Ca2BO3Cl:Tb3+ can produce green emission under 376 nm radiation excitation. With codoped A+ (A = Li, Na, K) as charge compensators, the relative emission intensities of Ca2BO3Cl:Tb3+ are enhanced by about 1.61, 1.97, and 1.81 times compared with those of the direct charge balance, which is considered to be due to the effect of the difference in ion radius on the crystal field. The CIE chromaticity coordinates of Ca2BO3CI:Tb3+, A+ (A = Li, Na, K) are (0.335, 0.584), (0.335, 0.585), and (0.335, 0.585), corresponding to the hues of green. Therefore, A+ (A = Li, Na, K) may be the optimal charge compensator for Ca2BO3Cl:Tb3+. 相似文献
83.
Xiangsi Liu Wenhua Zuo Bizhu Zheng Yuxuan Xiang Ke Zhou Zhumei Xiao Peizhao Shan Jingwen Shi Qi Li Guiming Zhong Riqiang Fu Yong Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(50):18254-18263
Sodium layered P2‐stacking Na0.67MnO2 materials have shown great promise for sodium‐ion batteries. However, the undesired Jahn–Teller effect of the Mn4+/Mn3+ redox couple and multiple biphasic structural transitions during charge/discharge of the materials lead to anisotropic structure expansion and rapid capacity decay. Herein, by introducing abundant Al into the transition‐metal layers to decrease the number of Mn3+, we obtain the low cost pure P2‐type Na0.67AlxMn1?xO2 (x=0.05, 0.1 and 0.2) materials with high structural stability and promising performance. The Al‐doping effect on the long/short range structural evolutions and electrochemical performances is further investigated by combining in situ synchrotron XRD and solid‐state NMR techniques. Our results reveal that Al‐doping alleviates the phase transformations thus giving rise to better cycling life, and leads to a larger spacing of Na+ layer thus producing a remarkable rate capability of 96 mAh g‐1 at 1200 mA g‐1. 相似文献
84.
Darryl D. Holm Vakhtang Putkaradze Cesare Tronci 《Physica D: Nonlinear Phenomena》2008,237(22):2952-2965
The gradient-flow dynamics of an arbitrary geometric quantity is derived using a generalization of Darcy’s Law. We consider flows in both Lagrangian and Eulerian formulations. The Lagrangian formulation includes a dissipative modification of fluid mechanics. Eulerian equations for self-organization of scalars, 1-forms and 2-forms are shown to reduce to nonlocal characteristic equations. We identify singular solutions of these equations corresponding to collapsed (clumped) states and discuss their evolution. 相似文献
85.
Takashi Uchida Masaya Tazawa Hiroshi Sakai Yoshihiro Kobayashi 《Applied Surface Science》2008,254(23):7591-7595
Radial breathing modes (RBMs) in resonance Raman spectra from single-walled carbon nanotubes (SWCNTs) on a SiO2/Si (0 0 1) substrate are studied between 25 and 720 °C. A change in the relative intensity of each RBM peak with temperature is observed, which originates from the temperature dependence of the resonance condition of nanotubes. For 25 °C, each RBM peak is reasonably assigned on the basis of data in the literature [J. Maultzsch, H. Telg, S. Reich, F. Hennrich, C. Thomsen, Phys. Rev. B 72 (2005) 205438]. By taking into account the temperature-dependent behavior of the relative intensity of the RBM peaks, each RBM peak is successfully assigned even for 720 °C. It is found that most of the observed RBM peaks for a laser excitation energy of Eexc = 1.96 eV are from chiral SWCNTs. These results make it possible to discuss further details of the chirality-dependent growth behavior observed for in situ Raman spectroscopy. 相似文献
86.
Spin Polarization and Andreev Conductance through a Diluted Magnetic Semiconductor Quantum Wire with Spin--Orbit Interaction
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Spin-dependent Andreev reflection and spin polarization through a diluted magnetic semiconductor quantum wire coupled to normal metallic and superconductor electrodes are investigated using scattering theory. When the spin-orbit coupling is considered, more Andreev conductance steps appear at the same Fermi energy. Magnetic semiconductor quantum wire separates the spin-up and spin-down electrons. The Fermi energy, at which different- spin-state electrons begin to separate, becomes lower due to the effect of the spin-orbit interaction. The spin filter effect can be measured more easily by investigating the Andreev conductance than by investigating the normal conductance. 相似文献
87.
88.
B. Lesiak J. Zemek P. Jiricek O. Gedeon A. Jóźwik 《Surface and interface analysis : SIA》2008,40(12):1507-1515
The Na? K (Na10K5) silicate glass, unirradiated and electron irradiated (electron dose from 25 to 8239 Cm?2) is investigated using XPS. The measurements are performed in the angular‐resolved ADES‐400 spectrometer using AlKα X‐ray radiation and an electron beam of energy 2 keV. Owing to surface charging and ambiguity of identification of the atomic oxidized chemical states, the line shapes of selected XPS transitions are analyzed with the aid of the pattern recognition (PR) method. This method is based on a distance measure and deals with spectra representation as vectors in the n‐dimensional space. The algorithm presented, called the fuzzy k‐nearest neighbor (fkNN) rule, allows for identification of ambiguous vectors with the membership vectors described by classes membership probabilities. Under electron irradiation, the Na and K content in a surface region undergoesincrease and then slow systematic decrease. The line shape analysis indicates difficult classification of XPS spectra recorded for unirradiated and irradiated glass, especially for Na 1s transition. The chemical state of Na is a mixture of elemental and oxidized form and remains unchanged for all electron doses. Larger changes in the chemical form are observed for the K atom. In an unirradiated silicate glass, a mixture of elemental and oxide form is observed with increasing content of oxide under irradiation. The alkali atoms, Na and K, exhibit a migration effect. Comparison of PR and fitting results indicates better reliability and accuracy of the PR method. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
89.
L. Seralessandri 《Journal of solid state chemistry》2008,181(8):1992-1997
Sodium ferrimanganite carbonatation reaction was investigated at different temperatures/carbon dioxide partial pressures to evaluate the feasibility of the thermochemical water-splitting cycle based on the MnFe2O4/Na2CO3/Na(Mn1/3Fe2/3)O2 system.After thermal treatments in selected experimental conditions, the obtained powder samples were investigated by using the X-ray diffraction (XRD) technique and Rietveld analysis.Two different lamellar Na1−xMn1/3Fe2/3O2−δ phases were observed together with the expected MnFe2O4/Na2CO3 mixture. Different equilibrium regions among sodium-depleted lamellar phases, manganese ferrite and sodium carbonate were found as a function of the different reaction conditions. A hypothesis concerning the regeneration mechanism of the initial compounds is proposed. Chemical equilibrium between stoichiometric and sub-stoichiometric forms of sodium ferrimanganite and sodium carbonate formation/dissociation appears to be essential factors governing the oxygen-releasing step of the manganese ferrite thermochemical cycle. 相似文献
90.
ChangYan Hu Dr. Ying Li Dr. Dong Wang Dr. Chunjin Wu Feng Chen Linghong Zhang Prof. Fang Wan Prof. Weibo Hua Prof. Yan Sun Prof. Benhe Zhong Dr. Zhenguo Wu Prof. Xiaodong Guo 《Angewandte Chemie (International ed. in English)》2023,62(46):e202312310
Na2Ti6O13 (NTO) with high safety has been regarded as a promising anode candidate for sodium-ion batteries. In the present study, integrated modification of migration channels broadening, charge density re-distribution, and oxygen vacancies regulation are realized in case of Nb-doping and have obtained significantly enhanced cycling performance with 92 % reversible capacity retained after 3000 cycles at 3000 mA g−1. Moreover, unexpected low-temperature performance with a high discharge capacity of 143 mAh g−1 at 100 mA g−1 under −15 °C is also achieved in the full cell. Theoretical investigation suggests that Nb preferentially replaces Ti3 sites, which effectively improves structural stability and lowers the diffusion energy barrier. What's more important, both the in situ X-ray diffraction (XRD) and in situ Raman furtherly confirm the robust spring effect of the Ti−O bond, making special charge compensation mechanism and respective regulation strategy to conquer the sluggish transport kinetics and low conductivity, which plays a key role in promoting electrochemical performance. 相似文献