772 research outputs found

    Electrocatalysis of Lithium (Poly-) Sulfides in Organic Ether-Based Electrolytes

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    This work aims at identifying an effective electrocatalyst for polysulfide reactions to improve the electrode kinetics of the sulfur half-cell in liquid organic electrolytes for alkali-sulfur cells. To increase the charge and discharge rates and energy efficiency of the cell, functionalized electrocatalytic coatings have been prepared and their electrode kinetics have been measured. To the best of our knowledge, there is no extensive screening of electrocatalysts for the sulfur electrode in dimethoxyethane:1,3-dioxolane (DME:DOL) electrolytes. In order to identify a suitable electrocatalyst, apparent exchange current densities at various materials (Al, Co, Cr, Cu, Fe, Steel, glassy carbon, ITO, Ni, Pt, Ti, TiN, Zn) are evaluated in a polysulfide electrolyte using potentiodynamic measurements with a Butler-Volmer fit. The chemical stability and surface morphology changes after electrochemical measurements are assessed with X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The results show that cobalt is a promising candidate with appropriate electrocatalytic properties for polysulfide reactions while being stable in the electrochemical environment, followed by chromium in terms of catalytic activity and stability. Sputtered TiN was found to be a very stable material with very low catalytic activity, a possible current collector for the cell

    Comment on ``Reduction of static field equation of Faddeev model to first order PDE'', arXiv:0707.2207

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    The authors of the article Phys. Lett. B 652 (2007) 384, (arXiv:0707.2207), propose an interesting method to solve the Faddeev model by reducing it to a set of first order PDEs. They first construct a vectorial quantity α\bm \alpha , depending on the original field and its first derivatives, in terms of which the field equations reduce to a linear first order equation. Then they find vectors α1\bm \alpha_1 and α2\bm \alpha_2 which identically obey this linear first order equation. The last step consists in the identification of the αi\bm \alpha_i with the original α\bm \alpha as a function of the original field. Unfortunately, the derivation of this last step in the paper cited above contains an error which invalidates most of its results

    Nurses\u27 Alumnae Association Bulletin - Volume 2 Number 2

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    Coming Events Come On, \u2732 Ballot for Officers Hospital News Legislation Scholarship Fund Notes Refresher Course Correspondence Use of Heparin in Modern Treatment The Jefferson Medical College Library Nursing School Education Action - Camera - Seniors Degrees Received Engagements Weddings Births Deaths Attention Alumnae Bulletin Progress Of Special Interest Army Assignments Organized Staff Meeting

    Nurses\u27 Alumnae Association Bulletin - Volume 2 Number 3

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    The Jefferson Nurse Letter from the President Delegates to Biennial Convention Attention Blood Transfusion - Plasma Unit Life in the Army Nurse Corps Secretary\u27s Report Elected to New Office 1892-1942 Progress or Alumnae Association 1892-1942 Report of the School of Nursing Staff News Please Change My Address Air Cooled Red Cross Report Fingerprinting Graduates in the U.S. Army and Navy Degrees Received Promotions Jubilee Report Engagements Marriages Births New Positions - 1941-1942 New Positions on the Nursing Staff of the Hospita

    Breakdown of Varvenne scaling in (AuNiPdPt)1−x_{1-x} Cux_{x} high-entropy alloys

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    The compositional dependence of the yield strength σy_{y} has been studied for a series of polycrystalline (AuNiPdPt)1−x_{1-x}Cux_{x} alloys by means of compression tests. σy_{y} is found to decrease linearly with increasing Cu concentration. This behaviour is in contradiction to the generalised theory for solid solution strengthening in concentrated solid solutions provided by Varvenne et al. [1]. A breakdown of the scaling behaviour is found as σy should be non-linear and slightly increasing when modifying the composition from AuNiPdPt to AuCuNiPdPt

    Promoting abnormal grain growth in Fe-based shape memory alloys through compositional adjustments

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    Iron-based shape memory alloys are promising candidates for large-scale structural applications due to their cost efficiency and the possibility of using conventional processing routes from the steel industry. However, recently developed alloy systems like Fe–Mn–Al–Ni suffer from low recoverability if the grains do not completely cover the sample cross-section. To overcome this issue, here we show that small amounts of titanium added to Fe–Mn–Al–Ni significantly enhance abnormal grain growth due to a considerable refinement of the subgrain sizes, whereas small amounts of chromium lead to a strong inhibition of abnormal grain growth. By tailoring and promoting abnormal grain growth it is possible to obtain very large single crystalline bars. We expect that the findings of the present study regarding the elementary mechanisms of abnormal grain growth and the role of chemical composition can be applied to tailor other alloy systems with similar microstructural features
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