Search results for "solut"
showing 10 items of 6365 documents
Experimental alteration of granitic rocks: Implications for the evolution of geothermal brines in the Upper Rhine Graben, Germany
2020
Abstract Geothermal energy exploitation in the Upper Rhine Graben (URG) chiefly has targeted faults and fractures within or connected with the crystalline basement, where hot fluids of c. 200 °C circulate at depths of c. 5 km. Formation fluids of the crystalline basement are highly saline, NaCl-dominated brines, whereas shallow crystalline basement water ( The trace element concentrations of the leachates are hereby related to the composition and stability of minerals in the rocks and can be directly linked to the proposed and observed dissolution processes at the different temperatures. In experiments with pure water at 70 °C, representing the recharge or infiltration conditions, water-roc…
Deconvolution of XPS spectra
1991
The resolution of XPS spectra is limited mainly by instrumental parameters like the spectral line width of the exciting X-ray source and the finite energy resolution of the electron analyzer. If the line broadening functions resulting from the instrumental setup can be estimated and expressed by a spectrometer function, a mathematical recalculation of the intrinsic signal is possible by deconvolution. With the method presented in this paper, a resolution enhancement by a factor of 3 can be obtained. Measured spectra of physically correlated spin orbit doublets have been deconvoluted, and it is shown, that the intensity ratios and the positions are comparable with results obtained by highly …
Atmospheric water vapor content over land surfaces derived from the AVHRR data: application to the Iberian Peninsula
1999
A study has been carried out using simulated NOAA/advanced very high resolution radiometer (AVHRR) data at 11 and 12 /spl mu/m (with LOWTRAN-7, MODTRAN 2.0, and the TIGR database), AVHRR images of the Iberian Peninsula and the Palma de Mallorca Island, radiosonde observations at seven meteorological stations, and the AVISO database provided by Meteo France to describe, compare, and analyze two different approaches for estimating the total atmospheric water vapor content (W) over land surfaces from AVHRR data. These two techniques are: 1) the split-window covariance-variance ratio (SWCVR), based on a quadratic relationship between W and the ratio of the spatial covariance and variance of bri…
Energy- and time-resolved microscopy using PEEM: recent developments and state-of-the-art
2008
Two novel methods of spectroscopic surface imaging are discussed, both based on photoemission electron microscopy PEEM. They are characterised by a simple electron-optical set up retaining a linear column. An imaging high-pass energy filter has been developed on the basis of lithographically-fabricated microgrids. Owing to a mesh size of only 7μm, no image distortions occur. The present energy resolution is 70 meV. The second approach employs time-of-flight energy dispersion and time-resolved detection using a Delayline Detector. In this case, the drift energy and the time resolution of the detector determine the energy resolution. The present time resolution is 180 ps, giving rise to an en…
Brominated Azaphilones from the Sponge-Associated Fungus Penicillium canescens Strain 4.14.6a
2019
The fungus Penicillium canescens was isolated from the inner tissue of the Mediterranian sponge Agelas oroides. Fermentation of the fungus on solid rice medium yielded one new chlorinated diphenyl ether (1) and 13 known compounds (2-14). Addition of 5% NaBr to the rice medium increased the amounts of 4-6, while lowering the amounts of 8, 12, and 14. Furthermore, it induced the accumulation of 17 and two new brominated azaphilones, bromophilones A and B (15 and 16). Compounds 15 and 16 are the first example of azaphilones with the connection of a benzene moiety and the pyranoquinone core through a methylene group. The structures of the new compounds were elucidated based on the 1D and 2D NMR…
Polymer-polymer interaction, in the presence of a solvent as measured by viscometry
2001
Dilute solution viscometry experiments have been carried out in five ternary polymer systems solvent(1)/polymer(2)/polymer(3). Values of the specific viscosity of polymer (3) in a ‘binary solvent’ formed by polymer(2) + solvent(1) have been used to determine the compatibility of the polymer blends. Krigbaum and Wall formalism has been used to predict compatibility which relies on an interaction parameter that depends on the concentration, weight fraction and molar mass of each polymer. To reduce the dependences and to clarify the criterion of compatibility, a parameter independent of polymer (3) composition and molar mass has been deduced. This parameter shows the same behaviour with polyme…
Cadmium and Copper Removal by a Granular Activated Carbon in Laboratory Column Systems
2000
Single and competitive removal of Cd and Cu from aqueous solutions by using Darco 12–20 mesh granular activated carbon in column systems has been investigated. Seven experiments modifying the initial pH and the flow rate were performed. Results showed the efficiency of activated carbon as a sorbent for both metals. pH is shown to be the decisive parameter on metal removal in the column; metal removal increases when the influent pH value is raised. The influence of the flow rate for the experimental conditions is negligible. Batch adsorption and column data are compared. Column modeling assuming local equilibrium and rate-controlled pore diffusion was performed.
Die stufenweise Syntheseo,o?-methylenverbr�ckter Cyclohexamerer mitp-Kresol- oderP-Kresol- und 4-tert-Butylphenol-Bausteinen Vergleich mit �hnlich st…
1981
Two phenolic alcohols with six phenolic units in their molecules have been obtained by stepwise syntheses starting from simple phenolic derivatives. The phenolic alcohols were cyclized in a one step cyclization by boiling in a very diluted acetic acid solution. A two step cyclization of a phenolic alcohol with three phenolic units to a cyclohexamer proceeds only with poor yields. The cyclic compounds were compared with chainlike oligomers containing six phenolic units in their molecules.
Influence of some aromatic and aliphatic compounds on the rate of photodegradation of phenol in aqueous suspensions of TiO2
1995
Abstract The influence of 3-nitrophenol, 4-nitrophenol, pentachlorophenol, ethanol, 2-propanol, ethanoic acid and ethanedioic acid on the photodegradation rate of phenol in an aqueous suspension of TiO2 (anatase) irradiated in the near-UV region was investigated. Binary mixtures of organic compound and phenol in molar ratios of 1:1 and 10:1 were used for the photoreactivity experiments performed in a batch reactor. The mineralization rate of all the mixtures was also monitored by measuring the total organic carbon (TOC) concentration. The reactivity results indicate that the photodegradation rate of phenol is mainly determined by the total amount of aromatic substrates present in the reacti…
Viscosimetric investigation of the interaction between sodium dodecylsulfate micelles and a polymer drug carrier
1993
Abstract The viscosities of aqueous sodium dodecyl sulfate solutions with and without α,β-poly( N -hydroxyethyl)- dl -aspartamide (PHEA), at 15, 25 and 35°C are reported. The viscosities of SDS and of PHEA aqueous solutions are discussed in terms of the parameter D [D = ( η η 0 − 1)/φ] describing the non-ideal behavior of SDS micelles and of PHEA macromolecules. The viscosities of SDS plus PHEA aqueous solutions, discussed in terms of the parameter F [ F = η rel ( PHEA ) + η rel ( SDS ) − η rel ( SDS + PHEA )] M , demonstrate the occurrence of interactions between SDS micelles and the PHEA macromolecule. Both D and F are scarcely influenced by temperature variation.