Publications

Showing 66 results for Author: Alexander Johs

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Aug, 2010

Conference Paper

Controlled Synthesis, Manipulation of Surface Hydrophobicity and Self-Assembly of Hematite Nanocrystals

The preparation of uniform iron oxide monolayer thin films is of great interest not only in advanced materials synthesis but also in studies of microbial cell and iron oxide mineral interface interactions by techniques such as neutron reflectometry, which requires the use of uniform thin films of the mineral on a substrate. Here we report three techniques for fabricating s…
Aug, 2010

Conference Paper

Molecular structure and dynamics in bacterial mercury resistance

Bacteria participate significantly in mercury transformation in natural and industrial environments. Previous studies have shown that bacterial mercury resistance is mediated by the mer operon, typically located on transposons or plasmids. It encodes specific genes that facilitate uptake of mercury species, cleavage of organomercurials, and reduction of Hg(II) to Hg(0). Ex…
Jun, 2010

Journal

Characterization of the Decaheme c-type Cytochrome OmcA in Solution and on Hematite Surfaces by Small Angle X-ray Scattering and Neutron Reflectometry

The outer membrane protein OmcA is an 85 kDa decaheme c-type cytochrome located on the surface of the dissimilatory metal reducing bacterium Shewanella oneidensis MR-1. It is assumed to mediate electron shuttling, generated by the bacteria’s metabolism, to extracellular acceptors that include solid metal oxides such as hematite (α-Fe2O3). To investigate the mechanism by wh…
May, 2010

Journal

Structure and Conformational Dynamics of the Metalloregulator MerR upon Binding of Hg(II)

The bacterial metalloregulator MerR is the index case of an eponymous family of regulatory proteins, which controls the transcription of a set of genes (the mer operon) conferring mercury resistance in many bacteria. Homodimeric MerR represses transcription in the absence of mercury and activates transcription upon Hg(II) binding. Here, the average structures of the apo an…
Oct, 2009

Journal

Thin Films of Uniform Hematite Nanoparticles: Controls on Surface Hydrophobicity and Self-Assembly

In this study we show that uniform hematite (�-Fe2O3) nanoparticle thin films with controlled layer thickness can be formed by Langmuir-Blodgett (LB) monolayer deposition on surface areas of several square centimeters. The technique involves synthesis of uniform hematite nanoparticles by forced hydrolysis and surface modifications for increased hydrophobicity to bring the…
Sep, 2009

Book Chapter

Application of Neutron Reflectivity for Studies of Biomolecular Structures and Functions at Interfaces

Structures and functions of cell membranes are of central importance in understanding processes such as cell signaling, chemotaxis, redox transformation, biofilm formation, and mineralization occurring at interfaces. This chapter provides an overview of the application of neutron reflectivity (NR) as a unique tool for probing biomolecular structures and mechanisms as a fir…

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Publications

Controlled Synthesis, Manipulation of Surface Hydrophobicity and Self-Assembly of Hematite Nanocrystals

Molecular structure and dynamics in bacterial mercury resistance

Characterization of the Decaheme c-type Cytochrome OmcA in Solution and on Hematite Surfaces by Small Angle X-ray Scattering and Neutron Reflectometry

Structure and Conformational Dynamics of the Metalloregulator MerR upon Binding of Hg(II)

Thin Films of Uniform Hematite Nanoparticles: Controls on Surface Hydrophobicity and Self-Assembly

Application of Neutron Reflectivity for Studies of Biomolecular Structures and Functions at Interfaces