Despite our extremely low atmospheric concentration of dihydrogen (B1 ppm), this substrate is a key metabolite of many anaerobic bacteria. In such living systems can be found the most prevalent enzymes for hydrogen processing, the nickel–iron hydrogenases ([NiFe]–H2ases). 1,2 These electrocatalysts specifically mediate the redox reaction H2 " 2H + + 2e at several hundred turnovers per second. T...

Reaction of [PPN][Fe(NO)2(SePh)2] (1) with dimeric [Ni(mu-SCH2CH2SCH2CH2S)]2 in the presence of additional NO2- produced the neutral heterobimetallic [(ON)Ni[(mu-SCH2CH2)2S]Fe(NO)2] complex (2). The X-ray crystal structures of 1 and 2 show distorted tetrahedral iron dinitrosyl groups, assigned according to the Feltham-Enemark notation as [Fe(NO)2]9 The Fe-NO bonds are off linearity by an averag...

The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the (57)Fe-labelled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F [NiFe]-hydrogenase. A unique 'wagging' mode involving H(-) motion perpendicular to the Ni(μ-H)(57)Fe pl...

Various morphologies of multi-walled carbon nanotubes (MWNTs) are grown catalytically on metalalloy probes in counterflow diffusion flames using methane as fuel. Carbon nanotube (CNT) properties and morphologies are investigated as functions of local gas-phase temperatures, C-related species concentrations (e.g. C2H2, CO), sampling positions, C2H2 adding to the fuel, and metal-alloy composition...

A rigorous study of electrodeposited pure and mixed Ni/Fe oxides was performed in three different sodium hydroxide electrolytes with various Fe impurity concentrations (<1 ppb, 5 ppb and 102 ppb). The presence and concentration of the Fe impurities in the three electrolytes is determined by Inductive Coupled Plasma spectroscopy. The rationale for investigating the OER performance of the pure an...

A variation of the relative content of (Fe+Ni) versus Ni may be responsible for the observed scatter of Type Ia Supernovae (SNe Ia) about a mean relation between their intrinsic brightness and the shape of their light curve. Synthetic light curves are computed of parametrised Chandrasekhar-mass explosion models of constant kinetic energy, where the ejecta are divided into an inner NSE zone, com...

Described herein are preparations of synthetic models for the deactivated Ni(II)Fe(II) states of the [NiFe]-hydrogenases. Iodination of the S = ½ species [(dppe)Ni(pdt)Fe(CO)(3)](+) afforded the diamagnetic iodo complex [(dppe)Ni(pdt)IFe(CO)(3)](+). Crystallographic analysis of this species confirmed the presence of square-pyramidal Ni linked to an octahedral Fe centre. The NiFe separation of 3...

Introduction: Isheyevo is a metal-rich carbonaceous chon-drite with metal-rich and metal-poor lithologies that are most similar to the CBb and CH chondrites, respectively [1]. All consist of similar components – Fe,Ni metal, chondrules, refractory inclusions, amoeboid olivine aggregates and heavily hydrated lithic clasts. We continued our investigation of these components of Isheyevo and found ...

We report the first Fe isotopic anomalies and the first Ni isotopic ratio measurements in presolar SiC grains of separate KJG from the Murchison meteorite. With NanoSIMS, we analyzed Fe and Ni in 37 X grains from Type II supernovae and 53 SiC grains of other types. TheNi/Fe and Co/Fe ratios in grains of all types aremuch higher than in the gas from which the grains are believed to have condense...