http://experimentationlab.berkeley.edu/sites/default/files/AFMImages/butt_AFM.pdf

Force measurements with the atomic force microscope: Technique, interpretation and applications

Structure and nanostructure in ionic liquids.

Post-transition elements, together with zinc-group metals and their alloys belong to an emerging class of materials with fascinating characteristics originating from their simultaneous metallic and liquid natures. These metals and alloys are characterised by having low melting points (i.e. between room temperature and 300 °C), making their liquid state accessible to practical applications in various fields of physical chemistry and synthesis. These materials can offer extraordinary capabilities in the synthesis of new materials, catalysis and can also enable novel applications including microfluidics, flexible electronics and drug delivery. However, surprisingly liquid metals have been somewhat neglected by the wider research community. In this review, we provide a comprehensive overview of the fundamentals underlying liquid metal research, including liquid metal synthesis, surface functionalisation and liquid metal enabled chemistry. Furthermore, we discuss phenomena that warrant further investigations in relevant fields and outline how liquid metals can contribute to exciting future applications.

Liquid metals: fundamentals and applications in chemistry

▪ Abstract Granular materials segregate. Small differences in either size or density lead to flow-induced segregation, a complex phenomenon without parallel in fluids. Modeling of mixing and segregation processes requires the confluence of several tools, including continuum and discrete descriptions (particle dynamics, Monte Carlo simulations, cellular automata computations) and, often, considerable geometrical insight. None of these viewpoints, however, is wholly satisfactory by itself. Moreover, continuum and discrete descriptions of granular flows are regime dependent, and this fact may require adopting different subviewpoints. This review organizes a body of knowledge that forms—albeit imperfectly—the beginnings of an expandable continuum framework for the description of mixing and segregation of granular materials. We focus primarily on noncohesive particles, possibly differing in size, density, shape, etc. We present segregation mechanisms and models for size and density segregation and introduce ch...

Mixing and Segregation of Granular Materials

Mineral–water interfacial structures revealed by synchrotron X-ray scattering

When a liquid makes contact with a solid wall, theoretical studies1,2,3,4 indicate that the atoms or molecules will become layered adjacent to the wall, giving rise to an oscillatory density profile. This expectation has not, however, been directly verified, although an oscillatory force curve is seen for liquids compressed between solid surfaces5. Here we present the results of an X-ray scattering study of liquid gallium metal in contact with a (111) diamond surface. We see pronounced layering in the liquid density profile which decays exponentially with increasing distance from the wall. The layer spacing is about 3.8 a, which is equal to the repeat distance of (001) planes of upright gallium dimers in solid α-gallium. Thus it appears that the liquid near thewall assumes a solid-like structure similar to the α-phase, which is nucleated on freezing at lower temperatures. This kind of ordering should significantly influence flow, capillary osmosis, lubrication and wetting properties5,6, and is likely to trigger heterogeneous nucleation of the solid.

/pdf/layering-of-a-liquid-metal-in-contact-with-a-hard-wall-4wpqtmdrwg.pdf

Layering of a liquid metal in contact with a hard wall

We have made a multimode waveguide of x rays having an air gap as the guiding medium. Individual transverse electric modes were found to propagate through the planar waveguide with essentially no attenuation and with negligible scattering losses to other modes. If different modes are excited simultaneously at the waveguide entrance, then the phase relation between these modes as given by their propagation constants is found to be preserved over the entire length of the waveguide.

/pdf/coherent-propagation-of-x-rays-in-a-planar-waveguide-with-a-1kyya9x4pp.pdf

Coherent Propagation of X Rays in a Planar Waveguide with a Tunable Air Gap

We have determined the structure of a colloidal fluid confined in a gap between two walls by making use of the waveguiding properties of the gap at x-ray wavelengths. The method is based on an analysis of the coupling of waveguide modes induced by the density variations in the confined fluid. Studies on suspensions confined within gaps of a few hundred nanometers showed strongly selective mode coupling effects, indicative of an ordering of the colloidal particles in layers parallel to the confining walls.

/pdf/x-ray-waveguiding-studies-of-ordering-phenomena-in-confined-461di0qqkk.pdf

X-Ray waveguiding studies of ordering phenomena in confined fluids

Focusing of X-rays in one dimension is achieved in a planar waveguide with linear taper. The waveguide consists of two plates with a variable tilt angle and an air gap between them. Compression of the beam and coherent mode coupling inside the waveguide result in a line focus of 26 nm height at the exit.

Focusing of coherent X-rays in a tapered planar waveguide

A linear-transmission Fresnel-zone-plate lens is used for coupling a monochromatic X-ray beam of 13.2 keV into a planar X-ray waveguide. The zone plate focuses the beam parallel to the entrance of the waveguide, by which means a flux enhancement of a factor of 54 inside the waveguide is obtained. This substantially enlarges the range of X-ray diffraction experiments that can be performed on samples confined within the waveguide. The coherent properties of the beam, as obtained at a third-generation synchrotron facility, are investigated by comparing the experimental data with numerical calculations in which partial coherence is taken into account by propagation of the mutual intensity function. The conditions for which the X-rays travelling through the waveguide are coherent are discussed.

M.J. Zwanenburg

Papers

Layering of a liquid metal in contact with a hard wall

Coherent Propagation of X Rays in a Planar Waveguide with a Tunable Air Gap

X-Ray waveguiding studies of ordering phenomena in confined fluids

Focusing of coherent X-rays in a tapered planar waveguide

Propagation of a partially coherent focused X-ray beam within a planar X-ray waveguide