Search results for "Analytical"
showing 10 items of 9586 documents
Studies on the UV-photolytic decomposition of some tensides and complexones inhibiting the inverse-voltammetric determination of metal ions
1993
The UV-photolytic decomposition of some tensides and complexones has been investigated using the DPASV peak of indium as an indicator. The results show that UV-irradiation alone can completely decompose these compounds at lower concentrations within a short time. Higher concentrations need an additional oxidising agent.
Optical absorption of zinc selenide doped with cobalt (Zn1−xCoxSe) under hydrostatic pressure
2000
Abstract The optical absorption of the diluted magnetic semiconductor Zn1−xCOxSe (x = 0.02) has been measured at room temperature under hydrostatic pressure up to 14GPa in a membrane diamond-anvil cell. We found two absorption features: (i) an absorption structure in the energy range 1.6−1.8eV, with a negligible pressure shift (i.e., 0.45 ± 0.05 meV/GPa) which we have identified as the Co2+(3d7) internal transition 4A2(F)→+4T1(P) and (ii) an onset in the energy range 2−2.7eV which redshifts with pressure (−8.1±0.6meV/GPa). We have attributed such absorption edge to charge transfer between the ZnSe valence band and the Co2+(3d7) levels.
New developments in immunochemical water analysis down to 30 mul sample volume.
1999
Abstract The determination of trace levels of pesticides like atrazine in water samples of small, restricted volumes is one of the future demands of environmental analysis. In a brief review existing chromatographic and immunochemical methods for atrazine are critically discussed. Then a simple rapid enzyme-linked immunosorbent assay (ELISA) using the tip of an inoculation needle as a solid surface is presented. The sample volume could be reduced to 30 μl. The assay had a centre of the test IC50 of 0.12 μg l−1 and permitted the characterisation of atrazine at levels of 0.022–2.90 μg l−1. A first outlook for automatisation is given. The new method was compared with an ELISA using 96 well mic…
Scintillation Measurements at Very High Solute Concentrations; Self Quenching-Structure Correlatios
1968
Abstract Measurements of the relative scintillation yields of some liquid organic systems were carried out with several highly soluble scintillator solutes. Self quenching was observed at high concentrations with some of the solutes, but not with others. The results were correlated with the ability of the solute molecules to come together, in a special configuration, close enough to form an association. A study of the atomic models of the solute molecules showed that those moleculeswith chromophor systems which were non-coplanar, or co-planar but shielded by substituent groups, did not produce self quenching. However, those solute molecules with unprotected co-planar chromophor systems did …
X-ray absorption near-edge structure of GaN with high Mn concentration grown on SiC.
2009
By means of x-ray absorption near-edge structure (XANES) several Ga(1-x)Mn(x)N (0.03x0.09) layers have been analyzed. The Mn-doped GaN samples consisted of different epilayers grown by molecular beam epitaxy on [0001] SiC substrates. The low mismatch between GaN and SiC allows for a good quality and homogeneity of the material. The measurements were performed in fluorescence mode around both the Ga and Mn K edges. All samples studied present a similar Mn ionization state, very close to 2+, and tetrahedral coordination. In order to interpret the near-edge structure, we have performed ab initio calculations using the full potential linear augmented plane wave method as implemented in the Wien…
Pyrene-fused bisphenazinothiadiazoles with red to NIR electroluminescence
2017
The synthesis and characterisation of two pyrene-fused phenazinothiadiazole derivatives with different substituents is described. Light-emitting diodes incorporating such derivatives display red to near-infrared electroluminescence with emission peaks at wavelengths as long as 721 nm, illustrating that pyrene-fused bisphenazinothiadiazoles can serve as deep red and NIR emitters.
A Theoretical and Experimental Study of Electrochemical pH Control at Gold Interdigitated Microband Arrays
2021
In electroanalysis, solution pH is a critical parameter that often needs to be adjusted and controlled for the detection of particular analytes. This is most commonly performed by the addition of chemicals, such as strong acids or bases. Electrochemical in-situ pH control offers the possibility for the local adjustment of pH at the point of detection, without additional reagents. FEA simulations have been performed to guide experimental design for both electroanalysis and in-situ control of solution pH. No previous model exists that describes the generation of protons at an interdigitated electrode array in buffered solution with one comb acting as a protonator, and the other as the sensor.…
Über die lösungswärme von polystyrol in verschiedenen lösungsmitteln
1951
An einem Polystyrol mit einem Molekulargewicht von ca. 20 000 werden die Losungs-warmen in verschiedenen Losungsmitteln in einem Kalorimeter bestimmt. Die meisten Losungsvorgange verlaufen exotherm, in einem Fall (Cyclohexan) wird jedoch bei der Auflosung Warme von der Umgebung aufgenommen. Es wird festgestellt, das die Trocknung der Praparate sehr wichtig fur die Reproduzierbarkeit der Messungen ist. Ferner wird orientierend die Abhangigkeit der Losungswarme vom Polymerisationsgrad sowie von der Konzentration der entstehenden Losung festgestellt. Es wird auserdem orientierend die Mischungswarme von Athylbenzol in verschiedenen Losungsmitteln bestimmt. Measurements of the heat of solution o…
Evaluation of the factors affecting direct polarization solid state (31)P-NMR spectroscopy of bulk soils
2008
Summary 31 P-NMR spectroscopy on bulk soils is a powerful tool for the identification of the different phosphorus forms in soils and for the evaluation of the dynamics of soil P. Up to now the majority of the papers dealt with liquid state 31 P-NMR spectroscopy on soluble soil organic substances. Only few papers were addressed to the study of the different phosphorus forms directly in bulk soils. In the present paper, some organic and inorganic phosphates of known structures, which are likely to be present in soil systems, were studied by direct polarization (DP) magic angle spinning (MAS) 31 P-NMR spectroscopy in order to understand the electronic factors responsible for chemical shifts of…
Revision of Na 2 A1Σ+u state molecular constants by polarization labeling spectroscopy
1997
ABSTRACT. This paper contains the analysis of the A1 of Na2 based on the data obtained from thepolarization labeling spectroscopy experiment on the A' —X' transition. A set of Dunham coefficients is derived, which describes the A state in the wide range of v and J 126) quantum numbers and reproduces the positions of unperturbed rotational lines in the A-X band system towithinO.1 cm'.1. INTRODUCTION.We report' new analysis of the A' state based on the data obtained from polarization labelingspectroscopy (PLS) experiment"2, based on V-type optical—optical double resonance scheme, on the 1 : ' ; band system of sodium dimer. The diatomic alkali molecules, with their simple electronic configurat…