Construction of a Semiconductor-Biological Interface for Solar Energy Conversion: p-Doped Silicon/Photosystem I/Zinc Oxide.

The interface between photoactive biological materials with two distinct semiconducting electrodes is challenging both to develop and analyze. Building off of our previous work using films of photosystem I (PSI) on p-doped silicon, we have deposited a crystalline zinc oxide (ZnO) anode using confined-plume chemical deposition (CPCD). We demonstrate the ability of CPCD to deposit crystalline ZnO without damage to the PSI biomaterial.

Nanodiamond nanofluids for enhanced thermal conductivity.

Deaggregation of oxidized ultradispersed diamond (UDD) in dimethylsulfoxide followed by reaction with glycidol monomer, purification via aqueous dialysis, and dispersion in ethylene glycol (EG) base fluid affords nanodiamond (ND)-poly(glycidol) polymer brush:EG nanofluids exhibiting 12% thermal conductivity enhancement at a ND loading of 0.9 vol %. Deaggregation of UDD in the presence of oleic acid/octane followed by dispersion in light mineral oil and evaporative removal of octane gives ND·oleic acid:mineral oil dispersions exhibiting 11% thermal conductivity enhancement at a ND loading of 1.

Multifunctional FePt nanoparticles for radiation-guided targeting and imaging of cancer.

A multifunctional FePt nanoparticle was developed that targets tumor microvasculature via "radiation-guided" peptides, and is detected by both near-infrared (NIR) fluorescence imaging and analytical mass spectrometry methods. Tumor specific binding was first measured by biotinylated peptide linked to fluorophore-conjugated streptavidin. This showed tumor selective binding to tumors using the HVGGSSV peptide.

Capture and release of alkyne-derivatized glycerophospholipids using cobalt chemistry.

Alkyne-modified phospholipids can be unambiguously identified and differentiated from native species in complex mixtures by formation of dicobalthexacarbonyl complexes. This reaction is specific for alkynes and is unaffected by other glycerophospholipid-related moieties. Enrichment of cells with alkyne-derivatized fatty acids or glycerophospholipids followed by solid-phase sequestration and release is a promising new method for unequivocally monitoring individual glycerophospholipids following incorporation into cells.

Confined-plume chemical deposition: rapid synthesis of crystalline coatings of known hard or superhard materials on inorganic or organic supports by resonant IR decomposition of molecular precursors.

A one-step process for preparing microcrystalline coatings of known superhard, very hard, or ultraincompressible ceramic compositions on either inorganic or organic supports is reported. Midinfrared pulsed-laser irradiation of preceramic chemical precursors layered between IR-transmissive hard/soft supports under temporal and spatial confinement at a laser wavelength resonant with a precursor vibrational band gives one-step deposition of crystalline ceramic coatings without incurring noticeable collateral thermal damage to the support material. Reaction plume formation at the precursor/laser beam interface initiates confined-plume, chemical deposition (CPCD) of crystalline ceramic product.

Synthesis and solid-state structure of a Pt-Ru-P ternary metal phosphide (PtRuP2) as a carbon nanocomposite.

Reactive thermal degradation of Pt(PPh3)(Cl)(mu2-Cl)2Ru(Cl)(eta3:eta3-C10H16)/Vulcan carbon powder composites gives a nanocomposite powder containing nanocrystals of the expected PtRu alloy phase along with nanocrystals of an unknown substance. Yields of the unknown phase increase when PPh3 is added to the composite prior to thermal treatment. The new substance has been identified as a ternary metal phosphide, PtRuP2.

Synthesis and characterization of potassium metal/graphitic carbon nanofiber intercalates.

Direct reaction of herringbone, platelet, or narrow, tubular herringbone graphitic carbon nanofibers (GCNFs) with molten potassium gives K/GCNF intercalates with stoichiometric control of potassium loading. Intercalate formation is confirmed by powder X-ray diffraction and micro-Raman spectroscopy. K/GCNF intercalates act as radical-anion alkene polymerization catalysts and reduce water with stoichiometric formation of hydrogen gas.

Mechanical characterization of nanofiber-reinforced composite adhesives.

Tensile and shear strength tests of metal/metal and polymer/polymer joints featuring a new functionalized nanofiber/epoxy composite adhesive were conducted. Strength increase is not as high as we expected (only up to 30%) although we used GCNF-ODA reactive linkers to improve the interface. The moderate strength increase is due to high interfacial stress developed in nanocomposites because of the high stiffness property mismatch, and inefficient interfacial shear stress transfer through shear-lag mechanism.

Formation of FePt nanoparticles having high coercivity.

Ultrasonication of toluene solutions of the heteropolynuclear cluster complex, Pt3Fe3(CO)15, in the presence of oleic acid and oleylamine affords surface-capped fcc FePt nanoparticles having an average diameter of ca. 2 nm. Self-assembled arrays of these nanoparticles on oxidized Si wafers undergo a fcc-to-fct phase transition at 775 degrees C to form ferromagnetic FePt nanocrystals ca.

Preparation of Pt-Re/Vulcan carbon nanocomposites using a single-source molecular precursor and relative performance as a direct methanol fuel cell electrooxidation catalyst.

Pt-Re/Vulcan carbon powder nanocomposites have been prepared with total metal loadings of 18 wt.% and 40 wt.% using a new non-cluster (1:1)-PtRe bimetallic precursor as the source of metal.

Carbothermal transformation of a graphitic carbon nanofiber/silica aerogel composite to a SiC/silica nanocomposite.

Carbon nanofiber/silica aerogel composites are prepared by sol-gel processing of surface-enhanced herringbone graphitic carbon nanofibers (GCNF) and Si(OMe)4, followed by supercritical CO2 drying. Heating the resulting GCNF/silica aerogel composites to 1650 degrees C under a partial pressure of Ar gas initiates carbothermal reaction between the silica aerogel matrix and the carbon nanofiber component to form SiC/silica nanocomposites. The SiC phase is present as nearly spherical nanoparticles, having an average diameter of ca.

Graphitic carbon nanofiber (GCNF)/polymer materials. I. GCNF/epoxy monoliths using hexanediamine linker molecules.

Processing methods have been optimized for the formation of graphitic carbon nanofiber (GCNF)/epoxy nanocomposites containing GCNFs highly dispersed throughout a thermoset epoxy matrix. GCNFs having a herringbone atomic structure are surface-derivatized with bifunctional hexanediamine linker molecules (GCNF-HDA) capable of covalent binding to an epoxy matrix during thermal curing and are cut to smaller dimension using high-power ultrasonication. GCNF-HDA nanofibers are dispersed in epoxy resin at 0.

Rapid preparation of Pt-Ru/graphitic carbon nanofiber nanocomposites as DMFC anode catalysts using microwave processing.

Pt-Ru/graphitic carbon nanofiber (GCNF) nanocomposites have been prepared on two different GCNF supports, with the use of a bimetallic precursor as a source of metal and microwave processing for thermal treatments. Pt-Ru nanoparticles appear as the major metal-containing component of these nanocomposites along with variable trace amounts of Ru metal. Use of microwave heating permits rapid preparation of these nanocomposites and affords metal nanoclusters of nearly uniform size.

Synthesis and characterization of PtSn/carbon and Pt3Sn/carbon nanocomposites as methanol electrooxidation catalysts.

Two Pt-Sn/vulcan carbon nanocomposites containing nanoclusters of PtSn (niggliite) and Pt3Sn highly dispersed on a carbon powder support have been prepared using Pt(SnPh2Cl)(PPh3)2(Ph) or [Pt3[mu-(PPh2)2CH2]3(mu 3-SnF3) (mu 3-CO)][PF6] as single-source precursors of metal alloy. PtP2 or Pt metal is also present as a secondary phase. Bimetallic Pt-Sn nanoclusters with an average diameter of 5-8 nm are formed at a total metal loading of ca.

Preparation of graphitic carbon nanofibers with the use of water-soluble supports.

Graphitic carbon nanofibers (GCNFs) are prepared from CO/H2 with a nickel-rich Fe-Ni (2:8) growth catalyst supported on three different water-soluble supports (Na4SiO4, Na2SiO3, and Na2CO3). GCNF products are formed with yield and crystallinity comparable to those of GCNF product produced with the same growth catalyst supported on fumed silica. Separation of GCNF product from the solid support is accomplished by aqueous dissolution of the support.

Particulate oral NMR contrast agents.

Insoluble paramagnetic compounds in suspension can be used to achieve visualization of the gastrointestinal system on magnetic resonance imaging (NMR). Particulate preparations of these agents decrease the T1 and T2 of solutions to which they are added. Gadolinium oxalate, a prototype of these particulate agents, was evaluated in vitro and in vivo (in rabbits) by NMR imaging.

Paramagnetic NMR contrast agents. Development and evaluation.

Paramagnetic ions could be theoretically used as NMR contrast agents because of their effect upon T1. However, the toxicity of these ions prevents their application. By the formation of appropriate chemical complexes with these ions, the toxicity of these agents can be substantially reduced while maintaining the paramagnetic effect.

Contrast enhancement of magnetic resonance images by chromium EDTA: an experimental study.

Chromium EDTA was evaluated as an intravenous contrast agent for magnetic resonance (MR) imaging in vitro and in vivo in rabbits and rats. The effect of Cr EDTA on T1 and T2 values in vitro was first quantitated by spectroscopy at 2.5 MHz, followed by animal trials in which the effects of intravenous injection of Cr EDTA on calculated T1 MR images (obtained by the spin- warp technique at 1.

Paramagnetic contrast agents in magnetic resonance imaging: research at Vanderbilt University.

Experimental studies in animals have demonstrated the application of particulate and chelated paramagnetic oral contrast agents in magnetic resonance imaging (at 0.5 tesla). The ability of a soluble paramagnetic species, ferrous gluconate, to improve imaging studies of the pancreas presently is being evaluated in clinical trials.

Paramagnetic agents for contrast-enhanced NMR imaging: a review.

The use of paramagnetic agents for contrast enhancement may extend the diagnostic potential of nuclear magnetic resonance (NMR) imaging. Proton relaxation is enhanced in targeted organ systems after either oral or intravenous administration of suitable paramagnetic agents. A decrease in T1 and T2, the spin-lattice and spin-spin relaxation times, can then be observed as an increase in signal intensity on NMR imaging.

Work in progress: potential oral and intravenous paramagnetic NMR contrast agents.

The potential use of paramagnetic compounds as nuclear magnetic resonance (NMR) contrast agents was examined in vitro. The T1 relaxation times for serial dilutions of Cu2+, Cr3+, Fe3+, and Mn2+ ions in saline, gadolinium oxalate (a potential oral contrast agent) in suspension, and chromium EDTA (a potential intravenous contrast agent) in solution were determined. The effect on T1 of increasing the concentration of oxygen in solution was also examined.