Mechanism of hydroxylamine mutagenesis: tautomeric shifts and proton exchange between the promutagen N6-methoxyadenosine and cytidine

Biochemistry ◽  
1987 ◽  
Vol 26 (14) ◽  
pp. 4332-4337 ◽  
Author(s):  
Ryszard Stolarski ◽  
Borys Kierdaszuk ◽  
Curt Eric Hagberg ◽  
David Shugar
Keyword(s):  
Proton Exchange ◽  
Hydroxylamine Mutagenesis

Mechanism of hydroxylamine mutagenesis: Role of tautomerism, conformation and proton exchange on base pairing between the promutagen N6 methoxyadenosine and uridine

1993 ◽  
Vol 46 (3) ◽  
pp. 207-215 ◽  
Author(s):  
Borys Kierdaszuk ◽  
Charlotta Johansson ◽  
Torbjorn Drakenberg ◽  
Ryszard Stolarski ◽  
David Shugar
Keyword(s):  
Proton Exchange ◽  
Base Pairing ◽  
Hydroxylamine Mutagenesis

Highly proton conductive membranes based on carboxylated cellulose nanofibres and their performance in proton exchange membrane fuel cells

2019 ◽  
Author(s):  
Valentina Guccini ◽  
Annika Carlson ◽  
Shun Yu ◽  
Göran Lindbergh ◽  
Rakel Wreland Lindström ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Surface Charge ◽  
Proton Exchange Membrane ◽  
Membrane Surface ◽  
Proton Exchange ◽  
Membrane Thickness ◽  
Fuel Cell Performance ◽  
Cellulose Nanofibres ◽  
Exchange Membrane

The performance of thin carboxylated cellulose nanofiber-based (CNF) membranes as proton exchange membranes in fuel cells has been measured in-situ as a function of CNF surface charge density (600 and 1550 µmol g<sup>-1</sup>), counterion (H<sup>+</sup>or Na<sup>+</sup>), membrane thickness and fuel cell relative humidity (RH 55 to 95 %). The structural evolution of the membranes as a function of RH as measured by Small Angle X-ray scattering shows that water channels are formed only above 75 % RH. The amount of absorbed water was shown to depend on the membrane surface charge and counter ions (Na<sup>+</sup>or H<sup>+</sup>). The high affinity of CNF for water and the high aspect ratio of the nanofibers, together with a well-defined and homogenous membrane structure, ensures a proton conductivity exceeding 1 mS cm<sup>-1</sup>at 30 °C between 65 and 95 % RH. This is two orders of magnitude larger than previously reported values for cellulose materials and only one order of magnitude lower than Nafion 212. Moreover, the CNF membranes are characterized by a lower hydrogen crossover than Nafion, despite being ≈ 30 % thinner. Thanks to their environmental compatibility and promising fuel cell performance the CNF membranes should be considered for new generation proton exchange membrane fuel cells.<br>

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