Search results for "Optical"
showing 10 items of 7671 documents
Densities and viscosities of imidazolium and pyridinium chloroaluminate ionic liquids
2013
Abstract The chloroaluminate ionic liquids are used in various types of reactions. However, due to their particular vulnerability on water, their physical properties have not been previously investigated very extensively. The densities and viscosities of series imidazolium and pyridinium chloroaluminate ionic liquids having alkyl (butyl, hexyl, octyl) or aralkyl (benzyl, ethylphenyl) chain at the cation, various effective molar fraction of AlCl 3 (χ AlCl3 = 0.5, 0.65, 0.7), as well as they mixture and mixture with common organic solvents (hexane, toluene) were measured at the temperature range 293.15–343.15 K (20–70 °C). Densities, and particularly viscosities decrease with the increase of…
Structural Investigation of Water/Lecithin/Cyclohexane Microemulsions by FT-IR Spectroscopy
1995
Abstract FT-IR spectra of water/lecithin/deuterated cyclohexane microemulsions as a function of water/lecithin molar ratio R ( R = [water]/[lecithin]) at various volume fractions ( O ) of the micellar phase have been recorded at 25°C. After elimination of the small spectral contributions due to deuterated cyclohexane and normalization, the shape of the C–H stretching band due to lecithin has been found dependent upon R and O whereas that of the O–H stretching band has been found dependent only upon R . The change in shape of the C–H band was interpreted in terms of a modification of the lecithin alkyl chain packing order. The analysis of the O–H band provides evidence that the hydroxylic gr…
Methyl-Substituted α-Cyclodextrin as Affinity Material for Storage, Separation, and Detection of Trichlorofluoromethane
2018
Abstract The severely ozone‐depleting trichlorofluoromethane is still appearing in several recycling processes or industrial applications. A simple and selective supramolecular complex formation of per‐methylated α‐cyclodextrin (1) with the highly volatile trichlorofluoromethane (2) is reported. This interaction moreover leads to thermally stable crystals. Per‐methylated α‐cyclodextrin is successfully exploited as a reversible and selective adsorption material for liquid and airborne trichlorofluoromethane as well as an affinity material for the chemical sensing and detection of this particular volatile organic component.
Structural characterization of U(VI) surface complexes on kaolinite in the presence of humic acid using EXAFS spectroscopy.
2007
To determine the influence of humic acid (HA), pH, and presence of atmospheric CO2 on the sorption of U(VI) onto kaolinite, the structure of the surface complexes was studied by U L III-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The best fits to the experimental EXAFS data were obtained by including two uranium coordination shells with two axial (O ax) and five equatorial (O eq) oxygen atoms at 1.77+/-0.02 and 2.34+/-0.02 A, respectively, and two coordination shells with one Al/Si atom each at 3.1 and 3.3 A. As in the case of the binary system U(VI)-kaolinite, uranium forms inner-sphere surface complexes by edge sharing with aluminum octahedra and/or silicon tetrahe…
Cationic Au Nanoparticle Binding with Plasma Membrane-like Lipid Bilayers: Potential Mechanism for Spontaneous Permeation to Cells Revealed by Atomis…
2014
Despite being chemically inert as a bulk material, nanoscale gold can pose harmful side effects to living organisms. In particular, cationic Au nanoparticles (AuNP+) of 2 nm diameter or less permeate readily through plasma membranes and induce cell death. We report atomistic simulations of cationic Au nanoparticles interacting with realistic membranes and explicit solvent using a model system that comprises two cellular compartments, extracellular and cytosolic, divided by two asymmetric lipid bilayers. The membrane-AuNP+ binding and membrane reorganization processes are discovered to be governed by cooperative effects where AuNP+, counterions, water, and the two membrane leaflets all contr…
Optical Absorption of Zinc Selenide Doped with Cobalt (Zn1-xCoxSe) under Hydrostatic Pressure
2000
Optical absorption of the diluted magnetic semiconductor Zn 1-x Co x Se (x = 0.02) has been measured at room temperature under hydrostatic pressure up to 14 GPa in a membrane diamond-anvil cell. We found two absorption features: (i) an absorption structure in the energy range 1.5 to 1.8 eV, with a negligible pressure shift (i.e. (0.45 ± 0.05) meV/GPa) which we have identified as the Co 2+ (3d 7 ) internal transition 4 A 2 (F) → 4 T 1 (P) and (ii) an onset in the energy range 2 to 2.7 eV which redshifts with pressure (dE/dP = (-8.1 ± 0.6) meV/GPa). We have attributed such absorption edge to charge transfer between the ZnSe valence band and the Co 2+ (3d 7 ) levels. On the assumption that tho…
Die chemische molekulargewichtsbestimmung von polystyrol mit hilfe colorimetrisch bestimmbarer endgruppen. III. Mitt.
1964
Ein mit dem Diacylperoxyd der 3-Benzolazo-benzoesare hergestelltes Polystyrol enthalt Endgruppen, die durch Extinktionsmessungen bei 442, 319 und 262,5 mμ bestimmt wurden. Es wurde eine Extinktionszahl-Molekulargewichts-Beziehung aufgestellt, die dem bekannten VAN'T HOFFschen Gesetz entspricht. Falls die Zahl der charakteristisch absorbierenden Endgruppen je Makromolekul unbekannt ist, wurden fur die experimentelle Bestimmung eines Mindestmolekulargewichts mehrere voneinander unabhangige Gleichungen gefunden. Viskosimetrisch und uber Extinktionsmessungen bestimmte Molekulargewichte wurden verglichen. Polystyrene, prepared by means of a diacylperoxide of the 3-benzeneazobenzoic acid, contain…
Changes in collagen cross-linking of articular cartilage are revealed by spectral reflectance imaging
2012
Excessive cross-linking of collagen during aging may contribute to degeneration of articular cartilage. Traditionally, the amount of cross-links is derived by using destructive high-performance liquid chromatography (HPLC). However, a sensitive, non-destructive method could help to evaluate tissue integrity, including cross-links. We increased collagen cross-linking in bovine articular cartilage by controlled threose incubation. During the incubation, optical spectral reflectance images of the samples were captured and related to HPLC results using regression analysis. Significant correlations with reflectance and cross-links were observed. When further developed the optical method may enab…
Divide and Protect: Passivating Cu(111) by Cu-(benzotriazole)2
2012
Binding of benzotriazolate anion (BTA) to copper complexes and Cu(111) surface was investigated by density functional theory calculations. [BTACuBTA]1– was found to be a very stable complex that BT...
DFT Study on the Complex Reaction Networks in the Conversion of Ethylene to Ethylidyne on Flat and Stepped Pd
2009
Adsorption and conversion of ethylene to ethylidyne on flat (111) and stepped Pd surfaces have been studied with the aim to unravel the complex chemistry of small organic molecules on Pd. These pro...