3,390 research outputs found
EXAFS, DFT, light-induced nucleobase binding, and cytotoxicity of the photoactive complex cis-[Ru(bpy)2(CO)Cl]+
No full textThe aqueous photochemistry of cis-[Ru(bpy)2(CO)Cl]+ (1) was investigated at 310 K and under visible light (white) irradiation by NMR and ESI-HR-MS. Complex 1 releases a Cl ligand, coordinates a solvent molecule, and forms the complex cis-[Ru(bpy)2(CO)(H2O)]2+ (2). Also, irradiation experiments were performed in the presence of the nucleobase derivatives 9-ethylguanine (9-EtG) and 9-ethyladenine (9-EtA). Formation of Ru-9-EtG adducts was observed after 3 h irradiation by NMR and HR-MS, while only very small amounts of a Ru-9-EtA adduct could be detected by HR-MS. Solution structural data were obtained by X-ray absorption spectroscopy (XAS) for both 1 and 2. EXAFS gave a Ru−Cl distance of 2.416(7) Å for 1 and a Ru−OH2O distance of 2.102(6) Å for 2. DFT and TDDFT were employed to study the photophysical and photochemical properties of 1. Calculations show that dissociative metal-centered states can be related to the light-induced release of a Cl ligand and subsequent coordination of a solvent molecule. The compound showed no antiproliferative activity in three human carcinoma cell lines (lung, bladder, pancreas) under the testing conditions, either with or without irradiation with UV light
白金微粒/Ru錯合物/高分子薄磨修飾電極之製備及其電催化應用
No full text[[abstract]]Membrane-metal modified cells are usually applied to the field of membrane cells, such as fuel cells, light cells… etc. Some hydrogen evolution catalysts, for example Pt metal, are used as the cathodes in these cells. Therefore, in this research, we try to dose a series of Ru complexes into the intervals between the cathode and the thin film electrode to improve the hydrogen evolution efficiency of the membrane-metal modified cells.
Ru complex (chosen from Ru(bpy)2phenNH2, Ru(dmb)2 phenNH2, Ru(tmb)2phenNH2, Ru(bpy)2Cl2, Ru(dmb)2Cl2, Ru(tmb)2Cl2) doped Nafion solution was drop-coated onto glassy carbon (GC) electrode and formed a thin film after drying. Then, the GC electrode was immersed into H2PtCl6 solution, and the Pt/Ru complex/polymer modified electrode was obtained by reducing Pt with a DPTB method. Different amount of Pt was electroplated on the GC electrode even at the same conditions (the same potential, the same time interval) when different consistency or kinds of Ru complexes were used, suggesting the influence of the ligands on the red-ox property of Ru complexes. The effective surface area (estimated by CV method) of Pt in the modified electrode is also varied with different species of Ru complexes, which in turn affect on the efficiency of hydrogen evolution.
Furthermore, from the information obtained by SEM and EDS, the alignment and the density of Pt particles growing on the GC electrode are figured out. From the fluorescence lifetime and luminescence spectra, a good electron-transfer is considered to have occurred between D series Ru complexes and Pt modified electrode that explained why a high hydrogen evolution efficiency has been obtained. The modified electrodes are still stable one month after fabricated and their hydrogen evolution efficiency was as good as a newly prepared one.
Photoactivated chemotherapy (PACT) : the potential of excited-state d-block metals in medicine
No full textThe fields of phototherapy and of inorganic chemotherapy both have long histories. Inorganic photoactivated chemotherapy (PACT) offers both temporal and spatial control over drug activation and has remarkable potential for the treatment of cancer. Following photoexcitation, a number of different decay pathways (both photophysical and photochemical) are available to a metal complex. These pathways can result in radiative energy release, loss of ligands or transfer of energy to another species, such as triplet oxygen. We discuss the features which need to be considered when developing a metal-based anticancer drug, and the common mechanisms by which the current complexes are believed to operate. We then provide a comprehensive overview of PACT developments for complexes of the different d-block metals for the treatment of cancer, detailing the more established areas concerning Ti, V, Cr, Mn, Re, Fe, Ru, Os, Co, Rh, Pt, and Cu and also highlighting areas where there is potential for greater exploration. Nanoparticles (Ag, Au) and quantum dots (Cd) are also discussed for their photothermal destructive potential. We also discuss the potential held in particular by mixed-metal systems and Ru complexes
Photophysical Characterization of Ru Nanoclusters on Nanostructured TiO<sub>2</sub> by Time-Resolved Photoluminescence Spectroscopy
No full textDespite the promising performance of Ru nanoparticles or nanoclusters on nanostructured TiO2 in photocatalytic and photothermal reactions, a mechanistic understanding of the photophysics is limited. The aim of this study is to uncover the nature of light-induced processes in Ru/TiO2 and the role of UV versus visible excitation by time-resolved photoluminescence (PL) spectroscopy. The PL at a 267 nm excitation is predominantly due to TiO2, with a minor contribution of the Ru nanoclusters. Relative to TiO2, the PL of Ru/TiO2 following a 267 nm excitation is significantly blue-shifted, and the bathochromic shift with time is smaller. We show by global analysis of the spectrotemporal PL behavior that for both TiO2 and Ru/TiO2 the bathochromic shift with time is likely caused by the diffusion of electrons from the TiO2 bulk toward the surface. During this directional motion, electrons may recombine (non)radiatively with relatively immobile hole polarons, causing the PL spectrum to red-shift with time following excitation. The blue-shifted PL spectra and smaller bathochromic shift with time for Ru/TiO2 relative to TiO2 indicate surface PL quenching, likely due to charge transfer from the TiO2 surface into the Ru nanoclusters. When deposited on SiO2 and excited at 532 nm, Ru shows a strong emission. The PL of Ru when deposited on TiO2 is completely quenched, demonstrating interfacial charge separation following photoexcitation of the Ru nanoclusters with a close to unity quantum yield. The nature of the charge-transfer phenomena is discussed, and the obtained insights indicate that Ru nanoclusters should be deposited on semiconducting supports to enable highly effective photo(thermal)catalysis.QN/Afdelingsburea
RU LOCAL Foods Initiative: Bringing the Farm to the Community through Local Advertising
No full textThe goal of the RU LOCAL group is to promote the purchasing of local foods through advertising at local grocery storesFall 201
Asymmetric Cyanation of α-Ketimino Ester Derivatives with Chiral Ru-Li Combined Catalysts
No full textAsymmetric cyanation of alpha-ketimino esters catalyzed by combined systems of amino acid/BINAP derivative/Ru-(II) complexes and lithium compounds was examined. The use of an appropriate combination of amino acid and BINAP ligands achieved high enantioselectivity for a variety of alpha-alkynyl (Val/XylBINAP/Ru), alpha-alkenyl (Val/TolBINAP/Ru), and alpha-aryl imino esters (Val/XylBINAP/Ru) as well as an isatin-derived cyclic imino amide (t-Leu/BINAP/Ru) to afford the alpha-cyano-alpha-amino esters and the amide with an alpha-nitrogen-substituted quaternary chiral center with up to 98% ee
Requirement for a core 1 galactosyltransferase in the Drosophila nervous system:
No full textGlycosylation is important in a lot of fundamental biological processes, including cell recognition, cell adhesion, and cell signaling. Mucin-type O-glycosylation involves the synthesis of glycoproteins, expressed in mucous secretions and as transmembrane proteins on the cell surfaces. However, the biological functions of mucin-type O-glycans remain incompletely understood. I have pursued genetic and biochemical studies to understand their importance during development in Drosophila.
Mucin-type O-glycosylation is initiated by the attachment of N-acetylgalactosamine (GalNAc) to Ser or Thr residues, and then elongated by additional sugars. To examine the requirements for mucin-type glycosylation in Drosophila, I characterized the expression and phenotypes of core 1 galactosyltransferases (core 1 GalTs), which elongate O-GalNAc by adding galactose in a β1, 3 linkage. Among Drosophila core 1 GalTs, CG9520 (C1GalTA) is expressed in the amnioserosa and central nervous system. A null mutation in C1GalTA is lethal. The mutant animals show a morphogenetic defect in their central nervous system in which the ventral nerve cord is greatly elongated and the brain hemispheres are distorted. Lectin staining and blotting experiments confirmed that C1GalTA is required for the synthesis of Gal-ß1,3-GalNAc in vivo. Our observations establish a role for mucin-type O-glycosylation during neural development in Drosophila.
Overexpression of C1GalTA causes a wing blistering phenotype, which occurs when adhesion between the two ventral and dorsal surfaces of the wing blade is lost, and is also commonly seen in integrin mutants. This result implicates mucin-type O-glycans in cell adhesion in the Drosophila wing blade.
Altogether, these results suggest a role of mucin-type O-glycosylation in Drosophila development, including the morphogenesis of central nervous system and the formation of the wing blade.Ph.D.Includes bibliographical references (p. 90-94)by Yuh-Ru Li
Site occupation in the Cr-Ru and Cr-Os ? phases
No full textThe site occupation in the Cr-Ru and Cr-Os ? phases is computed as a function of temperature. Generally, in ? phases the larger atoms occupy the sites with larger coordinations numbers, as can be explained on the basis of atomic-size and electronic structure. However, for Cr2Ru and Cr2Os the atomic-size argument predicts that Ru and Os occupy the sites with larger coordination numbers, whereas the reasoning based on the approximate degeneracies of electronic levels predicts that Cr occupies those sites. By comparing these predictions with the theoretically computed and the experimentally measured site occupations, the atomic-size and electronic arguments can be judged on their predictive merits.Materials Science and EngineeringMechanical, Maritime and Materials Engineerin
Synthesis of oligomeric and polymeric ethers containing the Cp*Ru+ and CpFe+ metal moieties.
No full textA variety of homometallic (Cp*Ru+) and heterometallic (CpFe+–Cp*Ru+) oligomers with one to five metal moieties were prepared in high yields (74–90%) via nucleophilic aromatic substitution reactions. For the mixed metal systems, it is shown that the arrangement of the metal moieties along the backbone can be controlled. In addition, the synthesis of heterometallic polymers is described, along with their decomplexation and thermal properties. It was found that the thermal properties and solubility of the systems are greatly dependent on the linkages within the polymer backbone
McEwen, B. /alt. author. Sexual differentiation of the brain
No full textRobert W. Goy, Bruce S. McEwen. Sexual differentiation of the brain: based on a work session of the Neurosciences Research Program
This book, based on a Work Session of MIT\u27s Neurosciences Research Program, presents a balanced account of a controversial topic&-the relative importance of genes, hormones, and environment in the formation of sexual behavior.https://digitalcommons.rockefeller.edu/ru-authors/1116/thumbnail.jp
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