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...

Bentonite has been modified using H2SO4 at various concentrations to alter the Si/Al ratio that is responsible for catalytic pyrolysis of waste polyethylene. The XRF analysis confirmed a gradual decrease Al2O3 content with an increasing concentration H2SO4. highest liquid hydrocarbon yield (87.48 %) was obtained 34.24. To further activate acid-modified bentonite, bimetals (Cu/Ni, Fe/Ni, and Co/...

Introduction: The Widmanstatten pattern develops at low temperatures during the evolution of the asteroids. We have studied the origin of the Widmanstatten pattern in order to obtain metallographic cooling rates in the temperature range (~ 700 to 300 deg C). This paper summarizes our recent evaluation of the various mechanisms for the formation of the Widmanstatten pattern. All chemical groups ...

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...

Steinhardtite is a new mineral from the Khatyrka meteorite; it is a new allotropic form of aluminum. It occurs as rare crystals up to ~10 μm across in meteoritic fragments that contain evidence of a heterogeneous distribution of pressures and temperatures during impact shock, in which some portions of the meteorite reached at least 5 GPa and 1200 °C. The meteorite fragments contain the high-pre...