Search results for "visual"
showing 10 items of 7386 documents
High activity of brookite TiO2 nanoparticles in the photocatalytic abatement of ammonia in water
2015
Abstract The effects of the TiO 2 crystal structure and its surface modification with Pt nanoparticles on the photocatalytic oxidation of NH 3 in the aqueous phase were studied with home-made TiO 2 photocatalyst powders synthesized by a thermo-hydrolysis approach that allowed a fine control of the crystallographic phase composition. Ammonia conversion and the selectivity toward mildly oxidized N 2 and highly oxidized nitrite and nitrate anions were monitored during the runs. Pure brookite powders modified by Pt nanoparticles, deposited either from a colloidal suspension or by deposition–precipitation, were found to be the most efficient photocatalysts in NH 3 degradation, with a desired goo…
Comparative multinuclear magnetic resonance spectroscopic study of transition metal (Cr, W and Mn) mesitylene tricarbonyls and transition metal (Ru a…
1993
Abstract Three mononuclear 1,3,5-trimethylbenzene (mesitylene) carbonyl transition metal complexes, mesitylene tricarbonyl chromium, (CH 3 ) 3 C 6 H 3 Cr(CO) 3 ( 1 ), mesitylene tricarbonyl tungsten, (CH 3 ) 3 C 6 H 3 W(CO) 3 ( 2 ), mesitylene tricarbonyl manganese tetra-fluoroborate, [(CH 3 ) 3 C 6 H 3 Mn(CO) 3 ]BF 4 ( 3 ); and three clusters, mesitylene nonacarbonyl tetracobalt, (CH 3 ) 3 C 6 H 3 Co 4 (CO) 9 ( 4 ), mesitylene carbido tetradecacarbonyl hexaruthenium, (CH 3 ) 3 C 6 H 3 Ru 6 C(CO) 14 ( 5 ) and carbido heptadecacarbonyl hexaruthenium, Ru 6 C(CO) 17 ( 6 ), have been studied by means of 1 H, 13 C and natural abundance 17 O NMR spectroscopy. Generally, the 1 H and 13 C NMR chemi…
Synthesis of Uvarovite Garnet
1989
A garnet with interesting optical properties is synthesized by means of the ceramic method and the formation of gels. Colloidal silica or tetraethoxysilane (TEOS) is used as a starting reagent in the latter method of synthesis, together with nitrate and chloride salts of the remaining components. Use is made of ultraviolet-visible and infrared spectroscopy techniques and X-ray diffraction in studying the evolution of the system. Formation of the garnet phase at lower temperatures is observed when using the gel methods, as well as the absence of chromates during the process in the samples which contained chlorides.
Synthesis, characterisation, crystal structures, and magnetic properties of one-dimensional oxalato-bridged metal(II) complexes with 3-hydroxypyridin…
2001
One-dimensional oxalato-bridged metal(II) compounds of formula [M(-ox)(L)2]n [L = 3-hydroxypyridine (pyOH) or isoquinoline (isq)] have been synthesised and characterised by FT-IR spectroscopy, TG-DTA techniques, variable-temperature magnetic measurements and X-ray diffraction methods. The complexes [M(-ox)(pyOH)2]n [M= Co (1), Ni (2)] are isomorphous and crystallise in the orthorhombic space group Pnab. The compounds [M(-ox)(isq)2]n [M= Co (3), Ni (4), Cu (5)] are also isomorphous and belong to the monoclinic space group C2/c. Crystal structures consist of zig-zag chains in which cis-[M(L)2] 2 + units are sequentially bridged by bis-bidentate oxalato ligands with intrachain M···M distances …
A Density Functional Theory study on gold cyanide interactions: The fundamentals of ore cleaning
2010
We have employed Density Functional Theory calculations to study the adsorption of CN, CN− and KCN on Au(111) and Au(211) surfaces and compare the obtained results to CO. The adsorption of CN, CN−, and KCN are exothermic with respect to the gas-phase moieties, and the adsorption energy increases at steps. Our results show that the binding mechanism of CN− is different from that of CO. The projected LDOS indicates that the bond between the flat surface and CN shows very small overlap between metal and CN states. This overlap increases provided that extra charge is present or low-coordinated Au atoms are available. Charge transfer is analyzed via the Bader method and the Electron Localization…
Micro-analytical identification of the components of varnishes from South Italian historical musical instruments by PLM, ESEM-EDX, microFTIR, GC-MS, …
2014
Abstract A multi-analytical investigation was carried out to study varnish micro-samples from historical stringed musical instruments from the collection of the “Vincenzo Bellini” Conservatory in Palermo (Italy). This paper reports on the results of the application of five micro-destructive techniques: optical microscopy analysis of cross-sections, micro-Fourier transform infrared spectroscopy, gas chromatography coupled with mass spectrometry, pyrolysis gas chromatography coupled with mass spectrometry with thermochemolysis, and environmental scanning electron microscopy with X-ray microanalysis. The study provides microchemical information about the composition of the varnishes of the ins…
Changes of humic substances characteristics from forested to cultivated soils in Ethiopia
2006
The dynamics of the stable fractions of soil organic matter (SOM), the humic substances, has been rarely studied in tropical soils. We evaluated extraction yields, elemental composition, isotopic d 13 C abundance and solid-state 13 C NMR spectra of humic fractions isolated from five forested and cultivated soils in Ethiopia in order to assess the influence of deforestation and subsequent cultivation on the composition of humic fractions. In all locations, humic (HA) and fulvic (FA) acids, humin (HU) and a humic hydrophobic fraction extracted with an acetone–HCl solution (HE) were decreased as a result of deforestation and cultivation, but the magnitude of decrease was site-specific. While t…
Adsorbed CO on group 10 metal fragments: A DFT study
2009
DFT calculations on the helicopter and cartwheel rotations of one CO molecule adsorbed at the bridge site on metal-surface fragments, characterized by two (M(8)) or three (M(14)) metal-atom layers (M = Ni, Pd, Pt) were performed by the B3LYP[LANL2DZ+6-31 g(d,p)] method, to rationalize the adsorption energetics and the steric hindrance characteristics of surface CO molecules. Potential Energy Surfaces were obtained, either fixing the C-O bond-length or allowing it to change. The behavior of the three metals, as obtained from the study of the configurational space characterizing the CO adsorption on the fragments was explained on the basis of the interaction energies involved in the different…
The influence of phosphoric acid on steel and on its corrosion products: a Mössbauer spectroscopic approach
1983
Mossbauer spectroscopy was used to study corroded iron after treatment with phosphoric acid or commercial rust transformers. It was found that treatment produced normal iron phosphates from metallic iron, hematite and FeO, and acid ferric phosphate FeH 3 (POI4I)I2I. 2.5H 2 O from alphaand gamma Fe 2 O 3 and alpha, beta, and gammaFeOOH. When these last are present, phosph oric acid treatment does not produce a protective, inhibiting layer. See also AATA 19-702. -- AATA
Electrochemical chiral recognition by microparticle coatings of Pd complexes with bridging cyclometalated phosphines
2008
Abstract The palladium(II) dinuclear complex with bridging cyclometalated phosphines, {Pd2[μ-(C6H4)PPh2]2(μ-O2CCH3)2} (Pd2L2), having a paddlewheel structure, is reversibly oxidized in CH2Cl2 to a dinuclear palladium(III) analogue via two successive one-electron steps. Solid state voltammetry of Pd2L2 in contact with aqueous electrolytes produce as one-electron oxidation with two competing mechanisms involving anion intercalation/anion binding between/to metal centres, chloride ions acting as inhibitors for the first pathway. R- and S-Pd2L2 produces a significant stereoselective electrocatalytic activity with respect to the oxidation of l - and d -glutamic acid in alkaline media.