نتایج جستجو برای: proton exchange

تعداد نتایج: 250490  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علم و صنعت ایران - دانشکده مهندسی شیمی 1387

لایه های نفوذ گازی نقش بسیار کلیدی را در بهبود عملکرد پیل سوختی ایفا می کنند. و بر اساس سه مفهوم هدایت الکتریکی بالاتر، مدیریت آب بهتر و عبور پذیری گاز بالاتر طراحی می شوند. ورقه های کربنی، پارچه های کربونی و فلزات سنتر شده به طور گسترده به عنوان لایه ن=فوذ گازی مورد استفاده قرار می گیرند. اما استفاده از نانو مواد شامل فیبرهای نانو کربنی و نانو لوله های کربنی موجب کاهش مقاومت تماسی، بهبود توزیع...

Journal: :Journal of the American Society for Mass Spectrometry 1995
E H Gur L J de Koning N M Nibbering

As part of an ongoing characterization of the intrinsic chemical properties of peptides, thermal hydrogen-deuterium exchange has been studied for a series of fast-atom-bombardment-generated protonated alkyldipeptides and related model compounds in the reaction with D2O, CH3OD, and ND3 in a Fourier transform ion cyclotron resonance mass spectrometer. Despite the very large basicity difference be...

Journal: :Biochemistry 1986
D Loftus G O Gbenle P S Kim R L Baldwin

A method for detecting structure in marginally stable forms of a protein is described. The principle is to measure amide proton exchange rates in the absence and presence of varying concentrations of a denaturant. Unfolding of structure by the denaturant is reflected by an acceleration of amide proton exchange rates, after correction for the effects of the denaturant on the intrinsic rate of ex...

2012
Minxiu Yan Liping Fan

Proton exchange membrane fuel cells have been causing attention because of theirs many advantages. In order to maintain good working condition good controller is required. In this study, the mathematical model for proton exchange membrane fuel cell is developed. Then combining the characteristics of fuzzy control and sliding mode control fuzzy sliding mode controller is designed. The controller...

2001
N. Kaiser

We calculate in heavy baryon chiral perturbation theory the local NN-potentials generated by the two-pion exchange diagrams at two-loop order. We give explicit expressions for the mass-spectra (or imaginary parts) of the corresponding isoscalar and isovector central, spin-spin and tensor NN-amplitudes. We find from two-loop two-pion exchange a sizeable isoscalar central repulsion which amounts ...

2008
Vassil B. Delchev Ivan G. Shterev Hans Mikosch

Twelve binary and eight ternary H-bonded systems between uracil and water=methanol were investigated at the B3LYP and MP2 theoretical levels using 6 31þG(d) basis functions. The binary and ternary systems that contain the hydroxo-uracil tautomer H-bonded with water and methanol were found to be the most stable complexes. The calculated energy barriers of the intermolecular proton exchange showe...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1976
D J Patel L Canuel

The well-resolved base and sugar proton resonances in the high resolution proton nuclear magnetic resonance (NMR) spectra of poly(dA-dT) can be monitored during the helix-coil transition. The observable resonances shift upfield on helix formation and the temperature-dependent chemical shifts exhibit a melting temperature t 1/2 = 69.9 +/- 0.3 degrees for 18.8 mM (with respect to phosphorus) poly...

A. Khoobroo, B. Fahimi,

The present paper explores the impact of an on-board hydrogen harvesting system (fuel reformer) on the overall efficiency of a fuel-cell powered vehicle. Various methods of hydrogen production for automotive applications have been discussed first. As the hydrogen production is one of the major challenges for application of proton exchange membrane (PEM) fuel cells, especially in vehicular indus...

2011
Kristin A. Herrmann Vicki H. Wysocki Erich R. Vorpagel

Aspartic acid (Asp)-containing peptides with the fixed charge derivative tris(2,4,6trimethoxyphenyl) phosphonium (tTMP-P ) were explored computationally and experimentally by hydrogen/deuterium (H/D) exchange and by fragmentation studies to probe the phenomenon of selective cleavage C-terminal to Asp in the absence of a “mobile” proton. Ab initio modeling of the tTMP-P electrostatic potential s...

2016
Douglas E. Stack Rachel Eastman

Regioselective labelling of arene rings via electrophilic exchange is often dictated by the electronic environment caused by substituents present on the aromatic system. Previously, we observed the presence of a t-butyl group, either covalently bond or added as an external reagent, could impart deuterium exchange to the unactivated, C1-position of estrone. Here, we provide nuclear magnetic reso...

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