Boron nitride nanotubes have been proposed as a suitable reinforcement for metal matrix composites. In order to be effective, the interaction between the metal and the nanotube needs to be strong while retaining the nanotube structure. Computational quantum chemistry was used to study interactions of aluminium and titanium metal clusters with boron nitride nanotubes. The effect of varying the r...

Monomethylamine (MMA, CH3NH2) can be used as a carbon and nitrogen source by many methylotrophic bacteria. Methylobacterium extorquens DM4 lacks the MMA dehydrogenase encoded by mau genes, which in M. extorquens AM1 is essential for growth on MMA. Identification and characterization of minitransposon mutants with an MMA-dependent phenotype showed that strain DM4 grows with MMA as the sole sourc...

All diazotrophic organisms sequenced to date encode a molybdenum-dependent nitrogenase, but some also have alternative nitrogenases that are dependent on either vanadium (VFe) or iron only (FeFe) for activity. In Azotobacter vinelandii, expression of the three different types of nitrogenase is regulated in response to metal availability. The majority of genes required for nitrogen fixation in t...

Iron-sulfur clusters are prosthetic groups that are required for the function of numerous enzymes in the cell, including enzymes important in respiration, photosynthesis, and nitrogen fixation. Here we report cloning of the human homolog of NifS, a cysteine desulfurase that is proposed to supply the inorganic sulfur in iron-sulfur clusters. In human cells, different forms of NifS that localize ...

This thesis concerns the materials science of carbon-based fullerene-like structures as a basis for the improvement of the applicability of FL-CNx protective thin films. In particular, structural origins of mechanical properties of FL-CNx coatings and water adsorption on their surface were investigated, both of which are critical parameters for their application as, e.g., computer hard disk pro...

We review the empirical pseudopotential method and its recent applications to the III–V nitride alloys GaAsN, GaPN, GaInAsN and GaAsPN. We discuss how studies using this method have provided an explanation for many experimentally observed anomalous nitride phenomena, including sharp photoluminescence lines in dilute alloys, high effective masses, Stoke’s shift between emission and absorption in...

Since iron-sulfur clusters exist in our oxidizing environment, it can be concluded that at one time in our evolutionary history that the environment was instead a reducing environment. Iron-sulfur clusters which contain high spin Fe(II) and Fe(III) tetracoordinated metals can help facilitate electron-transfer processes, nitrogen fixation, catalytic sites in hydrogenases, and oxidation of NADH t...

The sequestration of carbon and nitrogen by clay-sized particles in soils is well established, and clay content or mineral surface area has been used to estimate the sequestration potential of soils. Here, via incubation of a sieved (<2 mm) topsoil with labelled litter, we find that only some of the clay-sized surfaces bind organic matter (OM). Surprisingly, <19% of the visible mineral areas sh...

Current interests in the chemistry of high-nuclearity transition-metal complexes draw from their utility in the emerging science of nanomaterials, as models for the multimetal active sites of metal-storage proteins, and as single molecule magnets (SMMs). In addition, such super-sized molecules often show a variety of supramolecular interactions. The “self-assembly” process of generating a high-...

the local solid flow structure of gas-solid bubbling fluidized bed was investigated to identify and characterize the particle clusters. extensive mathematical calculations were carried out using the energy-minimization multi-scale (emms) approach for evaluating cluster properties including the velocity, the size and the void fraction of clusters in the dense phase of the bed. the results showed...