Reusable amine-based structural motifs for green house gas (CO2) fixation

A series of compounds with an amine based structural motif (ASM) have been synthesized for efficient atmospheric CO(2) fixation. The H-bonded ASM-bicarbonate complexes were formed with an in situ generated HCO(3)(-) ion. The complexes have been characterized by IR, (13)C NMR, and X-ray single-crystal structural analysis. ASM-bicarbonate salts have been converted to pure ASMs in quantitative yield under mild conditions for recycling processes.     

Self‐Assembly of a Mononuclear [FeIII(L)(EtOH)2] Complex Bearing an n‐Dodecyl Chain on Solid Highly Oriented Pyrolytic Graphite Surfaces

The synthesis and structures of the N‐[(2‐hydroxy‐3‐methyl‐5‐dodecylphenyl)methyl]‐N‐(carboxymethyl)glycine disodium salt (H L ) ligand and its neutral mononuclear complex [Fe^III( L )(EtOH)₂] ( 1 ) are reported. Structural and electronic properties of 1 were investigated by using scanning tunneling microscopy (STM) and current imaging tunneling spectroscopy (CITS) techniques. These studies reveal that molecules of 1 form well‐ordered self‐assemblies when deposited on a highly oriented pyrolytic graphite (HOPG) surface. At low concentrations, single or double chains (i.e., nanowires) of the complex were observed, whereas at high concentration the complex forms crystals and densely packed one‐dimensional structures. In STM topographies, the dimensions of assemblies of 1 found on the surface are consistent with dimensions obtained from X‐ray crystallography, which indicates the strong similarities between the crystal form and surface assembled states. Double chains are attributed to hydrogen‐bonding interactions and the molecules align preferentially along graphite defects. In the CITS image of complex 1 a strong tunneling current contrast at the positions of the metal ions was observed. These data were interpreted and reveal that the bonds coordinating the metal ions are weaker than those of the surrounding ligands; therefore the energy levels next to the Fermi energy of the molecule should be dominated by metal‐ion orbitals.     

Nanosized nickel oxide particles and modification with poly(methyl methacrylate)

In recent years, there is an increasing interest in the fabrication of inorganic–organic materials considering the remarkable change and improvement in properties. In this investigation, nanosized nickel oxide (NiO) particles were first prepared by calcination of nickel hydroxide precursor obtained by a simple liquid‐phase process. Mixed phases of NiO and nickel hydroxide were present as the calcination temperature was lower than 250°C. Non‐stoichiometric NiO was formed between 250°C and 350°C, and a pure NiO was obtained as the temperature reached 500°C. The surface characteristics of NiO particles were evaluated by measuring the adsorption behavior of anionic and cationic surfactants and some biomolecules. NiO/poly(methyl methacrylate) composite particles were then prepared using variable NiO/methyl methacrylate (MMA) ratio by seeded emulsion polymerization. The efficiency of NiO incorporation in the composite increased as the MMA content was increased in the recipe. The composite particles were colloidally stable, and the obtained particles were characterized by Fourier transform infrared, scanning electron microscopy, X‐ray diffraction, and X‐ray photoelectron spectra. Copyright © 2011 John Wiley & Sons, Ltd.     

Enzymeless determination of total sugar by luminol–tetrachloroaurate chemiluminescence on chip to analyze food samples

Chemiluminescence (CL) emission from luminol–tetrachloroaurate ([AuCl₄]^?) system studied in presence of monosaccharide sugars such as glucose and fructose was investigated on a microfluidic chip fabricated by the soft lithography technique. CL emission from the luminol–[AuCl₄]^? system at 430?nm was intensified remarkably by the catalytic activity of glucose and fructose at room temperature. Under optimized conditions, the CL emission intensity of the system was found to be linearly related to the concentration of the sugars. Based on this observation, nonenzymatic determination of total sugar (glucose, fructose, or hydrolyzable sucrose) was performed in a rapid and sensitive analytical method. The results revealed that the linearity ranged from 9 to 1,750?μM for glucose and 80 to 1,750?μM for fructose, with a limit of detection of 0.65 and 0.69?μM, respectively. The relative standard deviations determined at 250?μM based on six repetitive injections were 1.13 and 1.15?% for glucose and fructose, respectively. The developed method was successfully applied for determination of the total sugar concentration in food and beverages.

(1)H-(13)C INEPT MAS NMR correlation experiments with (1)H-(1)H mediated magnetization exchange to probe organization in lipid biomembranes

Two-dimensional (1)H-(13)C INEPT MAS NMR experiments utilizing a (1)H-(1)H magnetization exchange mixing period are presented for characterization of lipid systems. The introduction of the exchange period allows for structural information to be obtained via (1)H-(1)H dipolar couplings but with (13)C chemical shift resolution. It is shown that utilizing a RFDR recoupling sequence with short mixing times in place of the more standard NOE cross-relaxation for magnetization exchange during the mixing period allowed for the identification and separation of close (1)H-(1)H dipolar contacts versus longer-range inter-molecular (1)H-(1)H dipolar cross-relaxation. These 2D INEPT experiments were used to address both intra- and inter-molecular contacts in lipid and lipid/cholesterol mixtures.     

Structure,chemical bonding,and 45Sc solid state NMR of Sc2RuSi2

The silicide Sc₂RuSi₂ was synthesized from the elements by arc-melting. The structure was refined on the basis of single crystal X-ray diffractometer data: Zr₂CoSi₂ type, C2/m, a = 1004.7 (2), b = 406.8 (1), c = 946.6 (2) pm, β = 117.95 (2), wR2 = 0.0230, 743 F² values, and 32 variables. The structure consists of a rigid three-dimensional [RuSi₂] network in which the two crystallographically independent scandium atoms fill larger cages of coordination numbers 16 and 15, respectively. The [RuSi₂] network shows short Ru–Si distances (234–247 pm) and two different Si₂ pairs: Si1–Si1 at 247 and Si2–Si2 at 243 pm. Each silicon atom has trigonal prismatic Sc₆ (for Si2) or Sc₄Ru₂ (for Si1) coordination. These building units are condensed via common edges and faces. The various Sc–Sc distances between the prisms range from 327 to 361 pm. From electronic structure investigation within DFT, chemical bonding shows a major role of Ru–Si bonding and the presence of strong electron localization around Si–Si pairs pointing to a polyanionic silicide network [RuSi₂]^δ?. The ⁴⁵Sc MAS-NMR spectra recorded at 11.7 and 9.4 T clearly resolve the two distinct scandium sites. The large electric field gradients present at both scandium sites result in typical line shapes arising from second-order quadrupole perturbation effects.     

In situ Raman monitoring of materials under irradiation: study of uranium dioxide alteration by water radiolysis

In situ Raman scattering studies allow following real‐time evolutions of volume or surface structures under extreme conditions. In nuclear materials sciences, ion irradiation‐induced atomic organization modification and water radiolysis are of a major interest. In order to better understand these phenomena, we have developed an in situ versatile portable Raman spectroscopy system coupled with a cyclotron accelerator, allowing monitoring of a solid/liquid interface under irradiation and thus giving access to effects of radiolysis. The different parts of the system and their improvements are described in details. The system efficiency is highlighted by a comparative study of the time dependence of UO₂ surface modification induced, on one hand by contact with water under irradiation by 5 MeV He²⁺ particles, and on the other hand by pure chemical alteration, through contact with a hydrogen peroxide solution. Copyright © 2012 John Wiley & Sons, Ltd.     

Search for Down-Type Fourth Generation Quarks with the ATLAS Detector in Events with One Lepton and Hadronically Decaying W Bosons

This Letter presents a search for pair production of heavy down-type quarks decaying via b^{'}→Wt in the lepton+jets channel, as b^{'}b[over ˉ]^{'}→W^{-}tW^{+}t[over ˉ]→bb[over ˉ]W^{+}W^{-}W^{+}W^{-}→l^{±}νbb[over ˉ]qq[over ˉ]qq[over ˉ]qq[over ˉ]. In addition to requiring exactly one lepton, large missing transverse momentum, and at least six jets, the invariant mass of nearby jet pairs is used to identify high transverse momentum W bosons. In data corresponding to an integrated luminosity of 1.04 fb^{-1} from pp collisions at sqrt[s]=7 TeV recorded with the ATLAS detector, a heavy down-type quark with mass less than 480?GeV can be excluded at the 95% confidence level.     

Compact and silicon-on-insulator-compatible hybrid plasmonic TE-pass polarizer

Hybrid plasmonic waveguides consisting of a metal plane separated from a high-index medium by a low-index spacer have recently attracted much interest. Here we show that, by suitably choosing the dimensions and material properties of the hybrid waveguide, a very compact and broadband TE-pass polarizer can be implemented. Finite-difference time-domain simulation indicates that the proposed device can provide large extinction ratio with low insertion loss for the TE mode.