Abstract: A flow injection hydride generation graphite furnace atomic absorption spectrometric (FI-HG-GFAAS) method was applied to the determination of Se in Se-doped and undoped cereals and bakery products. For the purpose of doping, the soils used for the cultivation of the cereals were dosed with Se- doped foliar fertilizers. The samples were dissolved in a mixture of HNO(3) and H(2)O(2) solutions using micro-waveassisted digestion. The decomposition of H(2)Se generated from the sample solutions and the trapping of elemental Se were performed at a temperature of 300 degrees C on an Ir-pretreated integrated graphite platform of a transversally heated graphite atomizer(THGA). For release of the trapped Se within a fairly short atomization time (5s), an atomization temperature of 2200 degrees C was observed to be optimal. The overall efficiency of hydride generation, transport and trapping was similar to 86%. The upper limit of the linear dynamic range of calibration was 10 mu gL(-1), which corresponds to 0.5 mu g g(-1) for solid samples. Recovery of the samples spiked with Se(VI) solutions was found to be 93 +/- 6% on average. The relative standard deviation of the determinations was less than 8%. The limit of detection was found to be 0.06 mu gL(-1), corresponding to 3 ng g(-1) for solid samples. The accuracy of the method was verified with the use of IAEA-155 ( whey powder) certified reference material. End-capped THGA tubes resulted in an extension of the linear calibration range compared to that of standard THGAs. The Se content in bakery products made of undoped cereals ranged from 7.7 to 68 ng g(-1) ( wet weight) in 18 samples, whereas the Se content of the corresponding cereals was found to be below 100 ng g(-1) ( wet weight). The Se level of cereals grown on soils treated with Se- doped fertilizers ranged from 128 to 1046 ng g(-1) ( wet weight), and it depended linearly on the Se concentration of the corresponding foliar fertilizer.

Abstract: The ground-state energy of three-particle systems consisting of electrons and holes as found in semiconducting quantum wells is studied. The degree of confinement is determined by the quantum-well width and we can vary the dimensionality of the system from two to three dimensions. The energy levels of the system can further be altered by the application of an external magnetic field which is directed perpendicular to the well.

Abstract: The influence of the well width fluctuations on the dependence of the binding energy of excitonic complexes in quantum wells is studied by using the path-integral Monte-Carlo technique. The results are compared with available experimental data and a good agreement is found.

Abstract: Plants mainly rely on a mixture of Fe complexes with different organic ligands, like carboxylates and soluble fractions of water-extractable humic substances (WEHSs), to sustain the supply of this micronutrient. It has been demonstrated that the Fe-WEHS complex is more efficiently acquired by plant roots as it enhances functionality of the mechanisms involved in Fe acquisition at the root and leaf levels, allowing a faster recovery of the Fe-deficiency symptoms. The aim of this work is to verify whether this recovery involves also the allocation and accumulation of nutrients other than Fe to and within the leaf tissues. Iron-deficient plants treated with Fe-WEHS recovered more quickly the functionality both to uptake nitrate at the root level and to fixate CO2 in the leaves than those supplied with Fe-citrate. Concomitantly, Fe-WEHS-treated plants also accumulated other cationic nutrients faster and at a higher extent. Synchrotron 2D-scanning μ-X-ray fluorescence analyses of the leaves revealed that the recovery promotes a change in the allocation of these nutrients from the vascular system (K, Cu, and Zn) or trichomes (Ca and Mn) to the entire leaf blade. Fe-WEHS treatment efficiently promotes the recovery from Fe-deficiency-induced chlorosis with an enhanced allocation of other nutrients into the leaves and promoting their distribution into the entire leaf blade.

Abstract: The He-Ar-Cu+ IR laser operates in a hollow-cathode discharge, typically in a mixture of helium with a few-% Ar. The population inversion of the Cu+ ion levels, responsible for laser action, is attributed to asymmetric charge transfer between He+ ions and sputtered Cu atoms. The Ar gas is added to promote sputtering of the Cu cathode. In this paper, a hybrid modeling network consisting of several different models for the various plasma species present in a He-Ar-Cu hollow-cathode discharge is applied to investigate the effect of Ar concentration in the gas mixture on the discharge behavior, and to find the optimum He/Ar gas ratio for laser operation. It is found that the densities of electrons, Ar+ ions, Ar-m* metastable atoms, sputtered Cu atoms and Cu+ ions increase upon the addition of more Ar gas, whereas the densities of He+ ions, He-2(+) ions and He-m* metastable atoms drop considerably. The product of the calculated Cu atom and He+ ion densities, which determines the production rate of the upper laser levels, and hence probably also the laser output power, is found to reach a maximum around 1-5% Ar addition. This calculation result is compared to experimental measurements, and reasonable agreement has been reached.

Abstract: The chemical and physical alterations of cadmium yellow (CdS) paints in Henri Matisse's The Joy of Life (1905-1906, The Barnes Foundation) have been recognized since 2006, when a survey by portable X-ray fluorescence identified this pigment in all altered regions of the monumental painting. This alteration is visible as fading, discoloration, chalking, flaking, and spalling of several regions of light to medium yellow paint. Since that time, synchrotron radiation-based techniques including elemental and spectroscopic imaging, as well as X-ray scattering have been employed to locate and identify the alteration products observed in this and related works by Henri Matisse. This information is necessary to formulate one or multiple mechanisms for degradation of Matisse's paints from this period, and thus ensure proper environmental conditions for the storage and the display of his works. This paper focuses on 2D full-field X-ray Near Edge Structure imaging, 2D micro-X-ray Diffraction, X-ray Fluorescence, and Fourier Transform Infra-red imaging of the altered paint layers to address one of the long-standing questions about cadmium yellow alteration-the roles of cadmium carbonates and cadmium sulphates found in the altered paint layers. These compounds have often been assumed to be photo-oxidation products, but could also be residual starting reagents from an indirect wet process synthesis of CdS. The data presented here allow identifying and mapping the location of cadmium carbonates, cadmium chlorides, cadmium oxalates, cadmium sulphates, and cadmium sulphides in thin sections of altered cadmium yellow paints from The Joy of Life and Matisse's Flower Piece (1906, The Barnes Foundation). Distribution of various cadmium compounds confirms that cadmium carbonates and sulphates are photo-degradation products in The Joy of Life, whereas in Flower Piece, cadmium carbonates appear to have been a [(partially) unreacted] starting reagent for the yellow paint, a role previously suggested in other altered yellow paints.

Abstract: Samples of cretaceous limestone have been treated with three application methods (poultice, immersion and brushing) using different concentrations of ammonium oxalate solution (AmOx) and varying treatment time in order to test the efficiency of surface and in-depth formation of a protective layer of calcium oxalate (CaOx). Synchrotron-based microanalytical techniques (SR-mu XRD with 12.5 mu mx7.5 mu m (HxV) probe size, SR-mu FTIR with 10 mu mx10 mu m and 8 mu mx20 mu m probe sizes) and laboratory mu FTIR, XRD and SEM have been employed for analysis of the treated samples. Synchrotron-based techniques showed variations in the CaOx distribution along the surface on a micrometer scale. All treatments resulted in the development of a CaOx layer with a maximum thickness of approximately 40 mu m. Application by the brushing method with 10 1-min applications with 5-min breaks during one hour showed a development of the calcium oxalate layer equivalent to the poultice treatment taking 10 h. This treatment could be preferred for large marble or limestone surfaces where poultice usage is economically not feasible.

Abstract: In order to render paper hydrophobic for ink and thus adequate for writing, gelatine has been largely used. To this day, it is still employed in conservation workshops as an adhesive or a sizing agent, for instance, during the treatment of iron gall ink manuscripts. Various types and concentrations of gelatine are recommended, depending on the desired effect, but little information is available regarding to the physical distribution of gelatine in the paper. This aspect is however determinant for a better control of conservation treatments. In this work, we investigate the possibilities offered by FTIR microscopy for the measurement of the gelatine distribution in paper. Laboratory papers were preliminary treated with different types of gelatine and then embedded in a resin and cut in thin slices. Mapping techniques enable to compare the penetration of different types of gelatine in a semiquantitative way. The performance of conventional laboratory equipment and synchrotron radiation experimental setup are discussed.

Abstract: For the non-destructive identification of pigments and colorants in works of art, in archaeological and in forensic materials, a wide range of analytical techniques can be used. Bearing in mind that every method holds particular limitations, two complementary spectroscopic techniques, namely confocal ì-Raman spectroscopy (ì-RS) and ì-X-ray fluorescence spectroscopy (ì-XRF), were joined in one instrument. The combined ì-XRF and ì-RS device, called PRAXIS unites both complementary techniques in one mobile setup, which allows ì- and in situ analysis. ì-XRF allows one to collect elemental and spatially-resolved information in a non-destructive way on major and minor constituents of a variety of materials. However, the main disadvantages of ì-XRF are the penetration depth of the X-rays and the fact that only elements and not specific molecular combinations of elements can be detected. As a result ì-XRF is often not specific enough to identify the pigments within complex mixtures. Confocal Raman microscopy (ì-RS) can offer a surplus as molecular information can be obtained from single pigment grains. However, in some cases the presence of a strong fluorescence background limits the applicability. In this paper, the concrete analytical possibilities of the combined PRAXIS device are evaluated by comparing the results on an illuminated sheet of parchment with the analytical information supplied by synchrotron radiation ì-X-ray diffraction (SR ì-XRD), a highly specific technique.