The prevalent formation of noncrystalline U(IV) species in the subsurface and their enhanced susceptibility to reoxidation and remobilization, as compared to crystalline uraninite, raise concerns about the long-term sustainability of the bioremediation of U-contaminated sites. The main goal of this study was to resolve the remaining uncertainty concerning the formation mechanism of noncrystalli...

Native cellulose consists of a set of parallel chains composed of glucose. Most of the time, these chains are highly ordered and form a structure that is known as a microfibril. On the other hand, highly crystalline forms of cellulose are more difficult to process and often are unpredictable in their behavior. If an ordered but noncrystalline form of cellulose could be produced, this would grea...

We have imaged a 2D buried Ni nanostructure at 8 nm resolution using coherent x-ray diffraction and the oversampling phasing method. By employing a 3D imaging reconstruction algorithm, for the first time we have experimentally determined the 3D structure of a noncrystalline nanostructured material at 50 nm resolution. The 2D and 3D imaging resolution is currently limited by the exposure time an...

Wetlands often act as sinks for uranium and other trace elements. Our previous work at a mining-impacted wetland in France showed that a labile noncrystalline U(IV) species consisting of U(IV) bound to Al-P-Fe-Si aggregates was predominant in the soil at locations exhibiting a U-containing clay-rich layer within the top 30 cm. Additionally, in the porewater, the association of U(IV) with Fe(II)...

Ferromagnetic ${\mathrm{Co}}_{2}\mathrm{MnGa}$ has recently attracted significant attention due to effects related the nontrivial topology of its band structure. However, a systematic study canonical magnetogalvanic transport is missing. Focusing on high quality thin films, here we systematically measure anisotropic magnetoresistance (AMR) and thermoelectric counterpart magnetothermopower (AMTP...

We study the pressure-induced structural transformation of ${\mathrm{Ge}}_{136}$ clathrate by ab initio molecular dynamics and metadynamics. The system under pressure first undergoes amorphization followed an ultrafast recrystallization to $\ensuremath{\beta}$-tin structure on time scale 30 ps. initial is triggered high while subsequent fast driven low temperature. Interestingly, amorphous inte...

In this paper, we review some recent work on amorphous materials using current “first principles” electronic structure/molecular dynamics techniques. The main theme of the paper is to emphasize new directions in the use of such ab initio methods. Some of these, being quite new, need development, but we believe have promise for solving new and important kinds of problems in the physics of glassy...