Zinc-Silver, Zinc-Palladium, and Zinc-Gold as Bimetallic Systems for Carbon Tetrachloride Dechlorination in Water

Doping of zinc with silver, palladium, and gold was found to increase reactivity towards carbon tetrachloride in water. Commercial zinc dust, cryochemically prepared zinc metal particles (SMAD nanoparticles), and zinc dust pressed into pellets (mechanically activated zinc) were employed. Reduction products detected were methane, ethylene, acetylene, and other hydrocarbons along with products of partial dechlorination such as chloroform, methylene chloride, and methyl chloride. Dichloroethylenes (DCEs) and long-term reactions traces of trichloroethylene (TCE) were also detected. The use of zinc dust doped with palladium, gold, and silver resulted in 4-10 fold increases in carbon tetrachloride degradation rate and conversion into methane. Up to 30% of carbon tetrachloride was converted into methane by the Zn dust / 2 mol % Ag bimetallic system after the first six hours of reaction. Doping of activated forms of zinc, both cryoparticle and pellets, caused a further increase in methane formation and decrease in the concentration of methylene chloride. The data show that bimetallic enhancement with Pd, Ag, Au, as well as cryo and mechanical activation of zinc, enhances the metal surface reactivity and changes the priority of reaction pathways such that fully reduced products are favored. The “non-catalytic” gold metal was especially effective and this suggests that electron transfer, not catalytic hydrogenation, is rate determining

Magnetism in small bimetallic Mn-Co clusters

Effects of alloying on the electronic and magnetic properties of Mn$_{x}$Co$_{y}$ ($x+y$=$n$=2-5; $x$=0-$n$) and Mn$_2$Co$_{11}$ nanoalloy clusters are investigated using the density functional theory (DFT). Unlike the bulk alloy, the Co-rich clusters are found to be ferromagnetic and the magnetic moment increases with Mn-concentration, and is larger than the moment of pure Co$_n$ clusters of same size. For a particular sized cluster the magnetic moment increases by 2 $\mu_B$/Mn-substitution, which is found to be independent of the size and composition. All these results are in good agreement with recent Stern-Gerlach (SG) experiments [Phys. Rev. B {\bf 75}, 014401 (2007) and Phys. Rev. Lett. {\bf 98}, 113401 (2007)]. Likewise in bulk Mn$_x$Co$_{1-x}$ alloy, the local Co-moment decreases with increasing Mn-concentration.Comment: 11 pages, 15 figures. To appear in Physical Review

Graphene supported plasmonic photocatalyst for hydrogen evolution in photocatalytic water splitting

It is well known that the noble metal nanoparticles show active absorption in the visible region because of the existence of the unique feature known as surface plasmon resonance (SPR). Here we report the effect of plasmonic Au nanoparticles on the enhancement of the renewable hydrogen (H2) evolution through photocatalytic water splitting. The plasmonic Au/graphene/TiO2 photocatalyst was synthesized in two steps: first the graphene/TiO2 nanocomposites were developed by the hydrothermal decomposition process; then the Au was loaded by photodeposition. The plasmonic Au and the graphene as co-catalyst effectively prolong the recombination of the photogenerated charges. This plasmonic photocatalyst displayed enhanced photocatalytic H2 evolution for water splitting in the presence of methanol as a sacrificial reagent. The H2 evolution rate from the Au/graphene co-catalyst was about 9 times higher than that of a pure graphene catalyst. The optimal graphene content was found to be 1.0 wt %, giving a H2 evolution of 1.34 mmol (i.e., 26 μmolhˉ¹), which exceeded the value of 0.56 mmol (i.e., 112 μmolhˉ¹) observed in pure TiO2. This high photocatalytic H2 evolution activity results from the deposition of TiO2 on graphene sheets, which act as an electron acceptors to efficiently separate the photogenerated charge carriers. However, the Au loading enhanced the H2 evolution dramatically and achieved a maximum value of 12 mmol (i.e., 2.4 mmolhˉ¹) with optimal loading of 2.0 wt% Au on graphene/TiO2 composites. The enhancement of H2 evolution in the presence of Au results from the SPR effect induced by visible light irradiation, which boosts the energy intensity of the trapped electron as well as active sites for photocatalytic activity

Probing the role of the cation–π interaction in the binding sites of GPCRs using unnatural amino acids

We describe a general application of the nonsense suppression methodology for unnatural amino acid incorporation to probe drug–receptor interactions in functional G protein-coupled receptors (GPCRs), evaluating the binding sites of both the M2 muscarinic acetylcholine receptor and the D2 dopamine receptor. Receptors were expressed in Xenopus oocytes, and activation of a G protein-coupled, inward-rectifying K^+ channel (GIRK) provided, after optimization of conditions, a quantitative readout of receptor function. A number of aromatic amino acids thought to be near the agonist-binding site were evaluated. Incorporation of a series of fluorinated tryptophan derivatives at W6.48 of the D2 receptor establishes a cation–π interaction between the agonist dopamine and W6.48, suggesting a reorientation of W6.48 on agonist binding, consistent with proposed “rotamer switch” models. Interestingly, no comparable cation–π interaction was found at the aligning residue in the M2 receptor

Get screened: a pragmatic randomized controlled trial to increase mammography and colorectal cancer screening in a large, safety net practice

Abstract Background Most randomized controlled trials of interventions designed to promote cancer screening, particularly those targeting poor and minority patients, enroll selected patients. Relatively little is known about the benefits of these interventions among unselected patients. Methods/Design "Get Screened" is an American Cancer Society-sponsored randomized controlled trial designed to promote mammography and colorectal cancer screening in a primary care practice serving low-income patients. Eligible patients who are past due for mammography or colorectal cancer screening are entered into a tracking registry and randomly assigned to early or delayed intervention. This 6-month intervention is multimodal, involving patient prompts, clinician prompts, and outreach. At the time of the patient visit, eligible patients receive a low-literacy patient education tool. At the same time, clinicians receive a prompt to remind them to order the test and, when appropriate, a tool designed to simplify colorectal cancer screening decision-making. Patient outreach consists of personalized letters, automated telephone reminders, assistance with scheduling, and linkage of uninsured patients to the local National Breast and Cervical Cancer Early Detection program. Interventions are repeated for patients who fail to respond to early interventions. We will compare rates of screening between randomized groups, as well as planned secondary analyses of minority patients and uninsured patients. Data from the pilot phase show that this multimodal intervention triples rates of cancer screening (adjusted odds ratio 3.63; 95% CI 2.35 - 5.61). Discussion This study protocol is designed to assess a multimodal approach to promotion of breast and colorectal cancer screening among underserved patients. We hypothesize that a multimodal approach will significantly improve cancer screening rates. The trial was registered at Clinical Trials.gov NCT00818857http://deepblue.lib.umich.edu/bitstream/2027.42/78264/1/1472-6963-10-280.xmlhttp://deepblue.lib.umich.edu/bitstream/2027.42/78264/2/1472-6963-10-280.pdfPeer Reviewe

Experimental and theoretical investigation of ligand effects on the synthesis of ZnO nanoparticles

ZnO nanoparticles with highly controllable particle sizes(less than 10 nm) were synthesized using organic capping ligands in Zn(Ac)2 ethanolic solution. The molecular structure of the ligands was found to have significant influence on the particle size. The multi-functional molecule tris(hydroxymethyl)-aminomethane (THMA) favoured smaller particle distributions compared with ligands possessing long hydrocarbon chains that are more frequently employed. The adsorption of capping ligands on ZnnOn crystal nuclei (where n = 4 or 18 molecular clusters of(0001) ZnO surfaces) was modelled by ab initio methods at the density functional theory (DFT) level. For the molecules examined, chemisorption proceeded via the formation of Zn...O, Zn...N, or Zn...S chemical bonds between the ligands and active Zn2+ sites on ZnO surfaces. The DFT results indicated that THMA binds more strongly to the ZnO surface than other ligands, suggesting that this molecule is very effective at stabilizing ZnO nanoparticle surfaces. This study, therefore, provides new insight into the correlation between the molecular structure of capping ligands and the morphology of metal oxide nanostructures formed in their presence

GLIDA: GPCR—ligand database for chemical genomics drug discovery—database and tools update

G-protein coupled receptors (GPCRs) represent one of the most important families of drug targets in pharmaceutical development. GLIDA is a public GPCR-related Chemical Genomics database that is primarily focused on the integration of information between GPCRs and their ligands. It provides interaction data between GPCRs and their ligands, along with chemical information on the ligands, as well as biological information regarding GPCRs. These data are connected with each other in a relational database, allowing users in the field of Chemical Genomics research to easily retrieve such information from either biological or chemical starting points. GLIDA includes a variety of similarity search functions for the GPCRs and for their ligands. Thus, GLIDA can provide correlation maps linking the searched homologous GPCRs (or ligands) with their ligands (or GPCRs). By analyzing the correlation patterns between GPCRs and ligands, we can gain more detailed knowledge about their conserved molecular recognition patterns and improve drug design efforts by focusing on inferred candidates for GPCR-specific drugs. This article provides a summary of the GLIDA database and user facilities, and describes recent improvements to database design, data contents, ligand classification programs, similarity search options and graphical interfaces. GLIDA is publicly available at http://pharminfo.pharm.kyoto-u.ac.jp/services/glida/. We hope that it will prove very useful for Chemical Genomics research and GPCR-related drug discovery

Synthesis and characterization of the tetranuclear iron(III) complex of a new asymmetric multidentate ligand. A structural model for purple acid phosphatases

The ligand, 2-((2-hydroxy-5-methyl-3-((pyridin-2-ylmethylamino)methyl)benzyl)(2-hydroxybenzyl)amino)acetic acid (H(3)HPBA), which contains a donor atom set that mimics that of the active site of purple acid phosphatase is described. Reaction of H(3)HPBA with iron(III) or iron(II) salts results in formation of the tetranuclear complex, [Fe-4(HPBA)(2)(OAc)(2)(mu-O)(mu-OH)(OH2)(2)]ClO4 center dot 5H(2)O. X-Ray structural analysis reveals the cation consists of four iron(III) ions, two HPBA(3-) ligands, two bridging acetate ligands, a bridging oxide ion and a bridging hydroxide ion. Each binucleating HPBA(3-) ligand coordinates two structurally distinct hexacoordinate iron(III) ions. The two metal ions coordinated to a HPBA(3-) ligand are linked to the two iron(III) metal ions of a second, similar binuclear unit by intramolecular oxide and hydroxide bridging moieties to form a tetramer. The complex has been further characterised by elemental analysis, mass spectrometry, UV-vis and MCD spectroscopy, X- ray crystallography, magnetic susceptibility measurements and variable-temperature Mossbauer spectroscopy

Growth and transport properties of Y-Ba-Cu-O/Pr-Ba-Cu-O superlattices

The pulsed-laser deposition method has been used to fabricate epitaxial, nonsymmetric M(Y) {times} N(Pr) superlattices in which YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) layers either M = 1,2,3,4,8, or 16 c-axis unit cells thick are separated by insulating PrBa{sub 2}Cu{sub 3}O{sub 7-x} (PBCO) layers N unit cells thick (N = 1 to {approximately}32). The zero-resistance superconducting transition temperature, T{sub c0}, initially decreases rapidly with increasing PBCO layer thickness, but then saturates at T{sub c0} {approximately} 19 K, 54 K, 71 K, or 80 K, or structures containing 1-,2-,3-, or 4-cell-thick YBCO layers, respectively. Critical current density measurements carried out on structures with 16- or 32-cell thick YBCO layers show that the magnitude of J{sub c}(H = 0) {approximately} 1-2 MA/cm{sup 2}, as well as the magnetic field dependence and the anisotropy of J{sub c}(H) all are in good agreement with corresponding measurements on thicker, single-layer YBCO films. Thus, there is no evidence of an enhanced J{sub c}(H) due to the multi-layered structure, for the layer thickness investigated to date. The systematic variation of T{sub c0}, as a function of the YBCO and PBCO layer thickness, is discussed in light of other recent experiments and theoretical model calculations. The superlattices' structural and compositional order are characterized using x-ray diffraction, transmission electron microscopy, and scanning tunneling microscopy, and details of the pulsed-laser deposition process are reported. 42 refs., 7 figs

Heavy ion injector for the CERN Linac 1

An injector system has been designed to provide a fully stripped oxygen beam for acceleration in the CERN PS complex. An ECR source will provide an O/sup 6/+ beam to a heavy ion RFQ accelerator. The beam from the RFQ will be further accelerated by the CERN Linac 1 (Old Linac) in the 2 ..beta.. lambda-mode to an energy of 12.5 MeV/u at which point it will be fully stripped for subsequent acceleration in the CERN synchrotrons. The specifications of the new equipment and modifications to the existing linear accelerator are described