Origin and Detection of Microstructural Clustering in Fluids with Spatial-Range Competitive Interactions

Fluids with competing short-range attractions and long-range repulsions mimic dispersions of charge-stabilized colloids that can display equilibrium structures with intermediate range order (IRO), including particle clusters. Using simulations and analytical theory, we demonstrate how to detect cluster formation in such systems from the static structure factor and elucidate links to macrophase separation in purely attractive reference fluids. We find that clusters emerge when the thermal correlation length encoded in the IRO peak of the structure factor exceeds the characteristic lengthscale of interparticle repulsions. We also identify qualitative differences between the dynamics of systems that form amorphous versus micro-crystalline clusters.Comment: 6 pages, 5 figure

MOLECULAR DESIGN OF COLLOIDS IN SUPERCRITICAL FLUIDS

The environmentally benign, non-toxic, non-flammable fluids water and carbon dioxide (CO2) are the two most abundant and inexpensive solvents on earth. Emulsions of these fluids are of interest in many industrial processes, as well as CO2 sequestration and enhanced oil recovery. Until recently, formation of these emulsions required stabilization with fluorinated surfactants, which are expensive and often not environmentally friendly. In this work we overcame this severe limitation by developing a fundamental understanding of the properties of surfactants the CO2-water interface and using this knowledge to design and characterize emulsions stabilized with either hydrocarbon-based surfactants or nanoparticle stabilizers. We also discovered a new concept of electrostatic stabilization for CO2-based emulsions and colloids. Finally, we were able to translate our earlier work on the synthesis of silicon and germanium nanocrystals and nanowires from high temperatures and pressures to lower temperatures and ambient pressure to make the chemistry much more accessible

A high frequency search for radio pulsars in EGRET error boxes

We present a new survey for pulsars in the error boxes of the low-latitude EGRET sources 3EG J1027-5817, 3EG J1800-2338 and 3EG J1810-1032. Although all of these sources have been covered by previous pulsar surveys, the recent discovery of the young, energetic pulsar PSR J1410-6132 at 6.7 GHz has shown that pulsars of this type can be hidden from low frequency surveys. Using an observing frequency of 3.1 GHz we discovered a 91-ms pulsar, PSR J1028-5819, which observations made at the Parkes telescope and the Australia Telescope Compact Array have shown to be young and energetic. We believe this pulsar is likely to be powering the unidentified EGRET source 3EG J1027-5817. Like other energetic pulsars, PSR J1028-5819 is highly linearly polarised, but astonishingly has a pulse duty cycle of only 0.4%, one of the smallest in the entire pulsar catalogue.Comment: For publication in Monthly Notices of the Royal Astronomical Societ

Insoluble drug delivery

Particles of water insoluble biologically active compounds, particularly water-insoluble drugs, with an average size of 100 nm to about 300 nm, are prepared by dissolving the compound in a solution then spraying the solution into compressed gaz, liquid or supercritical fluid in the presence of appropriate surface modifiers.Board of Regents, University of Texas Syste

Pulsar Timing with the Parkes Radio Telescope for the Fermi Mission

We report here on two years of timing of 168 pulsars using the Parkes radio telescope. The vast majority of these pulsars have spin-down luminosities in excess of 10^34 erg/s and are prime target candidates to be detected in gamma-rays by the Fermi Gamma-Ray Space Telescope. We provide the ephemerides for the ten pulsars being timed at Parkes which have been detected by Fermi in its first year of operation. These ephemerides, in conjunction with the publicly available photon list, can be used to generate gamma-ray profiles from the Fermi archive. We will make the ephemerides of any pulsars of interest available to the community upon request. In addition to the timing ephemerides, we present the parameters for 14 glitches which have occurred in 13 pulsars, seven of which have no previously known glitch history. The Parkes timing programme, in conjunction with Fermi observations, is expected to continue for at least the next four years.Comment: Accepted for publication in PASA.12 page

Insoluble drug delivery

Particles of water insoluble biologically active compounds, particularly water-insoluble drugs, with an average size of 100 nm to about 300 nm, are prepared by dissolving the compound in a solution then spraying the solution into compressed gaz, liquid or supercritical fluid in the presence of appropriate surface modifiers.Board of Regents, University of Texas Syste

Water electrolysis on La1−xSrxCoO3−δ perovskite electrocatalysts

Perovskite oxides are attractive candidates as catalysts for the electrolysis of water in alkaline energy storage and conversion systems. However, the rational design of active catalysts has been hampered by the lack of understanding of the mechanism of water electrolysis on perovskite surfaces. Key parameters that have been overlooked include the role of oxygen vacancies, B–O bond covalency, and redox activity of lattice oxygen species. Here we present a series of cobaltite perovskites where the covalency of the Co–O bond and the concentration of oxygen vacancies are controlled through Sr[superscript 2+] substitution into La[scubscript 1−x]Sr[scubscript x]CoO[scubscript 3−δ]. We attempt to rationalize the high activities of La[scubscript 1−x]Sr[scubscript x]CoO[scubscript 3−δ] through the electronic structure and participation of lattice oxygen in the mechanism of water electrolysis as revealed through ab initio modelling. Using this approach, we report a material, SrCoO[subscript 2.7], with a high, room temperature-specific activity and mass activity towards alkaline water electrolysis.Robert A. Welch Foundation (grant F-1529)Robert A. Welch Foundation (grant F-1319)MIT Skoltech Initiative (Massachusetts Institute of Technology. Center for Electrochemical Energy Storage