Search results for "OXIDE"

Reaktionen an Aluminiumoxiden. 5. Mitt.: Umsetzungen von Cyclohexanon an Aluminiumoxid

1974

Die Umsetzungen von Cyclohexanon (1) an verschiedenen Aluminiumoxiden wurden bei unterschiedlichen Bedingungen untersucht. Die dabei entstandenen Stoffe wurden durch Vergleichssubstanzen mit Hilfe der DC und GC nachgewiesen. Reactions on Aluminium Oxides The reactions of cyclohexanone (1) on various aluminium oxides were investigated under different conditions. The resulting products were identified using synthesized compounds by aid of TLC and GLC.

Properties of native ultrathin aluminium oxide tunnel barriers

2003

We have investigated planar metal–insulator–metal tunnel junctions with aluminium oxide as the dielectricum. These oxide barriers were grown on an aluminium electrode in pure oxygen at room temperature till saturation. By applying the Simmons model we derived discrete widths of the tunnelling barrier, separated by Δs ≈ 0.38 nm. This corresponds to the addition of single layers of oxygen atoms. The minimum thickness of s0 ≈ 0.54 nm is then due to a double layer of oxygen. We found a strong and systematic dependence of the barrier height on the barrier thickness. Breakdown fields up to 5 GV m−1 were reached. They decreased strongly with increasing barrier thickness. Electrical breakdown could…

Cu–Cu interactions in the transparent p-type conductors: CuAlO2 and SrCu2O2

2003

Abstract Electronic structures of the p-type Transparent Conducting Oxides (TCO): CuAlO2 and SrCu2O2 are calculated using the Tight Binding Linearized Muffin Tin Orbital within the Atomic Sphere Approximation method (TB-LMTO-ASA). The band structures indicate two gaps for CuAlO2 (an indirect one with ΔE≈0.45 eV and a direct one with ΔE≈1.25 eV) and one direct gap for SrCu2O2 (with ΔE≈2 eV). In both oxides the Cu states are dominant at the top of the valence band, close to the Fermi level and the existence of weak Cu–Cu bonding interactions is revealed through the Integrated Crystal Orbital Hamiltonian Population (ICOHP). The presence of such interactions suggests that for the hole doped oxi…

The Effect of Electronic Properties of Anodized and Hard Anodized Ti and Ti6Al4V on Their Reactivity in Simulated Body Fluid

2022

The electronic properties of barrier and porous layers on Ti and Ti6Al4V were studied. Barrier anodic oxides grown to 40 V on Ti and on Ti6Al4V are both n-type semiconductors with a band gap of 3.3 eV and 3.4 eV respectively, in agreement with the formation of amorphous TiO2. Anodizing to 200 V at 20 mA cm−2 in calcium acetate and β-glycerol phosphate disodium pentahydrate leads to the formation of Ca and P containing porous films with a photoelectrochemical behaviour dependent on the metallic substrate. A band gap of 3.2 eV and the flat band potential of −0.5 V vs Ag/AgCl were measured for the porous oxide on Ti, while optical transitions at 2.15 eV and a significantly more positive flat b…

Cationic amino acid transport across the blood-brain barrier is mediated exclusively by system y+.

2006

Cationic amino acid (CAA) transport is brought about by two families of proteins that are found in various tissues: Cat (CAA transporter), referred to as system y+, and Bat [broad-scope amino acid (AA) transporter], which comprises systems b0,+, B0,+, and y+L. CAA traverse the blood-brain barrier (BBB), but experiments done in vivo have only been able to examine the BBB from the luminal (blood-facing) side. In the present study, plasma membranes isolated from bovine brain microvessels were used to identify and characterize the CAA transporter(s) on both sides of the BBB. From these studies, it was concluded that system y+was the only transporter present, with a prevalence of activity on the…

Unveiling the Chemo‐ and Regioselectivity of the [3+2] Cycloaddition Reaction between 4‐Chlorobenzonitrile Oxide and β‐Aminocinnamonitrile with a MED…

2021

New chiral α-aminophosphine oxides and sulfides: an unprecedented rhodium-catalyzed ligand epimerization

2001

International audience; New chiral α-aminophosphine oxide N,P(O) and sulfide N,P(S) ligands have been prepared in one-pot syntheses by addition of Ph2PH to (S)-PhCH[double bond, length half m-dash]NCH(Ph)CH3, followed by oxidation with O2 or S8. Crystallization from cold methanol leads to the isolation of an enantiomerically pure single N,P(O) diastereomer and to a 1 : 1 mixture of the two N,P(S) diastereomers. The coordination chemistry of these ligands with [RhCl(COD)]2 and [RhCl(CO)2]2 has been investigated under argon and syngas. At high temperatures, a P–C oxidative addition of the N,P(O) ligand followed by imine elimination leads to several hydrido rhodium species. The complexes conta…

Effect of Temperature on N2O and NO Emission in a Partial Nitrification SBR Treating Reject Wastewater

2017

Temperature is a very important parameter during nitritation, having a direct effect on ammonia oxidation rate (AOR) and enzymatic activities which relate to both N2O and NO emission. This study aims at investigating the effect of temperature on AOR, N2O and NO production in an enriched ammonia oxidizing bacteria (AOB) sequencing batch reactor (SBR) performing partial nitrification (PN) of synthetic reject wastewater. To achieve that, a SBR was subject to several shifts in temperature (in the range of 30 to 15 °C, 5 °C for each decrease). Cycle studies, which contain two aeration phases, were conducted under each temperature. The results showed that AOR specific exponentially correlates wit…

Contribution of Bacteria to Initial Input and Cycling of Nitrogen in Soils

2005

Nitrogen was discovered by the Scottish chemist and physician Daniel Rutherford in 1772 by removing oxygen and carbon dioxide from air. At the same time, the French chemist, Antoine Laurent Lavoisier, isolated what we would call nitrogen and named it azote, meaning without life since it did not support life or combustion. However, nitrogen is the fourth most common element in many biomolecules, which are essential for life, being outrankedonly by carbon, hydrogen andoxygen. Thus, nitrogen is found in amino acids that form proteins and in the nucleoside phosphates of nucleic acids. The cycle of nitrogen in soil has been studied more extensively than any other nutrient cycle. Nevertheless, de…

Templated growth of smart nanocomposite thin films: Hybrid aerosol assisted and atmospheric pressure chemical vapour deposition of vanadyl acetylacet…

2009

Hybrid aerosol assisted and atmospheric pressure chemical vapour deposition methodology has been utilised to produce nanocomposite thin films of gold nanoparticles and vanadium dioxide from vanadyl acetylacetonate and auric acid. The addition of tetraoctyl ammonium bromide (TOAB) to the precursor Solution gave control of the size and distribution of gold nanoparticles in the vanadium oxide matrix. These reactions led to vanadium dioxide films with reduced crystallite sizes and enhanced thermochromic properties. The films were analysed by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. Their optical and thermochromic behaviour was also determined, This h…