Four-way junctions (4Hs) are important intermediates in DNA rearrangements such as genetic recombination. Under the influence of multivalent cations these molecules undergo a conformational change, from an extended planar form to a quasi-continuous stacked X-structure. Recently, a number of X-ray structures and a nuclear magnetic resonance (NMR) structure of 4Hs have been reported and in three ...

The shape and structural evolution of Co nanoparticles embedded in SiO2 and subjected to swift heavy-ion irradiation have been investigated over a wide energy and fluence range. Modifications of the nanoparticle size and shape were characterized with transmission electron microscopy and small-angle x-ray scattering. Nanoparticles below a threshold diameter remained spherical in shape and progre...

Jupiter’s unique x-ray aurora is driven by the same processes as Earth’s: Heavy ion scattering electromagnetic waves.

A structural investigation o f a 1.1 molal BeCl2 aqueous solution has been performed by a molecular dynamics simulation together with X-ray diffraction studies o f 1.1 and 5.3 molal BeCl2 aqueous solutions at pH = \. A central force model in combination with an improved intra­ molecular three-body potential was used for water. The ion-water and ion-ion potentials were derived from ab initio cal...

In amorphous SiO2 (a-SiO2), a technologically most important material, average structural properties of ion tracks have been inferred from macroscopic measurements, yet details of the track structure and inner morphology are difficult to retrieve due to the lack of sufficient contrast inherent with most techniques. Here we report on measurements of a fine structure in ion tracks in a-SiO2 using...

A pentagonal ring is suggested as the basic structural unit of HCl(H2O)6 and (HCl)2(H2O)6 in solution. Modeled after the X-ray structure of a caged H13O6 compound, it contains bridged H5O2 and Clions, each with a coordination number around four. In the most concentrated HCl solutions, one of the ligands solvating Clis HCl, giving rise to a bichloride moiety. The proposed structure explains qual...

Hydration shells around ions are crucial for many fundamental biological and chemical processes. Their local physicochemical properties are quite different from those of bulk water and hard to probe experimentally. We address this problem by combining soft X-ray spectroscopy using a liquid jet and molecular dynamics (MD) simulations together with ab initio electronic structure calculations to e...

Ion irradiation induced modifications of a periodic Pt/C multilayer system containing Fe impurity have been analyzed by X-ray techniques suitable for exploring nanometer depth scales with sub-nanometer depth resolution. The multilayer stack with 15 Pt/C layer pairs (period 4.23 nm, total thickness 63.45 nm) was fabricated on a glass substrate. A 2 MeV Au2þ ion beam was rastered on the sample to...

We report a X-ray diffraction and molecular dynamics study on three choline-based bio-ionic liquids, choline formate, [Ch] [For], choline propanoate, [Ch][Pro], and choline butanoate, [Ch][But]. For the first time, this class of ionic liquids has been investigated by X-ray diffraction. Experimental and theoretical structure factors have been compared for each term of the series. Local structura...

soil samples were collected from seven sites in and around the metropolitan area of mexicocity. the locations were chosen as possible sources of fugitive dusts which contribute to suspended particulate matter in the atmosphere of mexico city. x-ray fluorescence (xrf) was used to determine the concentrations of several major elements (si, k, ca, ti, mn, and fe), as well as of other trace element...