Fluorous,chromatography-free Mitsunobu reaction

[formula: see text] The reaction of secondary and primary alcohols with highly fluorinated 3,4,5-tris(5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heptadecafluorododecan- 1-yloxy)benzoic acid in the presence of Ph3P and DIAD in THF at room temperature (fluorous Mitsunobu) resulted in a simple, chromatography-free isolation protocol with excellent yields (83-96%).     

Trace element XRF analysis of Mongolian coals

X-ray fluorescence has been applied as an analytical technique for the trace element characterization of Mongolian coals. Coal, samples from five regions of Mongolia are found to contain variable amounts of many trace elements. Various approaches to quantitative XRF analysis including a simple quantitative method, an emission-transmission method and a full fundamental parameter method are compared.     

Application of X-ray fluorescence spectrometry in assessment of environmental pollution

A conventional X-ray fluorescence (XRF) method as well as total reflection XRF have been applied to the analysis of various environmental materials. Some methodological changes in order to extend the applicability range and improve the accuracy of the XRF analysis are also discussed.     

Dramatic enhancement of third-harmonic generation in three-dimensional photonic crystals

We have observed a dramatic enhancement of third-harmonic generation in 3D polystyrene-air photonic crystals pumped by a near infrared laser beam. As the pump wavelength is tuned, the peak of the enhancement occurs when the third-harmonic wavelength approaches the short-wavelength edge of the band gap. We show that the origin of the enhancement is phase matching provided by the periodic structure of the photonic crystals.     

Nanoscopic study of second-harmonic generation in organic crystals with collection-mode near-field scanning optical microscopy

Collection-mode near-field scanning optical microscopy (NSOM) is used to map nanoscopic second-harmonic generation (SHG) in N -(4-nitrophenyl)- (L) -prolinol crystals. A spatial resolution of 98 nm is achieved. Near-field polarization-dependent SHG measurement is performed, and a local effective SHG susceptibility of 224+/-18 pm/V is obtained.     

Self-collimation in photonic crystals with anisotropic constituents

In a photonic crystal composed of anisotropic constituents we quantify the range of input angles and the degree of collimation of the beam inside the crystal. The optical properties of a photobleached 4-dimethylamino-N-methyl-4-stilbazolium-tosylate (DAST) crystal are used in our model to demonstrate the efficacy of the self-collimation features.     

Riboflavin as a source of autofluorescence in Eisenia fetida coelomocytes

Immunocompetent cells of earthworms (coelomocytes) contain adherent amoebocytes and large eleocytes (chloragocytes); the latter are filled with numerous granules. We have previously shown that eleocytes of several (but not all) earthworm species exhibit strong autofluorescence detectable by fluorescent microscopy and flow cytometry. In the present article, the molecular origin of eleocytes autofluorescence was elucidated in coelomocytes expelled via dorsal pores in the integument of Eisenia fetida subjected to electric shock (1 min at 4.5 V). Spectrofluorometry (excitation and emission spectra and fluorescence lifetime), together with HPLC analysis of coelomocyte suspensions and supernatants, indicated that riboflavin but not FMN (flavin mononucleotide) or FAD (flavin-adenine dinucleotide) is the main fluorophore responsible for eleocyte fluorescence in this species. Additionally, lipofuscins are suspected to participate in this phenomenon.     

Soil SO-1 reference material for trace analysis

Summary The preparation of soil SO-1 reference material is described as well as an evaluation of the results provided by 30 laboratories for 41 elements, including outlier rejection step by four concurrent tests. The influence of different chemical pretreatment methods preceding various instrumental analytical techniques is also discussed. Based on the numbers of outliers, confidence limits and numbers of different analytical methods used for a given element some criteria for the classification of the results are proposed.

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Referenzmaterial Soil SO-1 für die Spurenanalyse

     

Energy-dispersive X-ray spectrometry: present state and trends

Summary Recent development, present state and expected future developments in energy-dispersive X-ray spectrometry are discussed. Attention is paid to the improvements in analytical selectivity, sensitivity, detection limit, quantitative character and applicability range, which are the result of new or better excitation sources, detectors, instrument design, automation, computer software and theoretical developments.

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Energiedispersive Röntgenspektrometrie: Gegenwärtiger Stand und Trends

Zusammenfassung Neuere Entwicklungen, gegenwärtiger Stand und erwartete zukünftige Entwicklungen innerhalb der energiedispersiven Röntgenspektrometrie werden vorgestellt. Herausgestellt werden vor allem die Verbesserungen hinsichtlich der Selektivität, der Empfindlichkeit, der Nachweisgrenzen, der Quantifizierung und des Anwendungsbereiches. Die Fortschritte sind das Ergebnis neuer oder besserer Anregungsquellen und Detektoren, der Konstruktion und Automation, der Computer-Software und der Entwicklungen innerhalb der Theorie.

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On leave from: Institute for Physics and Nuclear Techniques, Academy of Mining and Metallurgy, PL-30-059 Cracow, Poland

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On leave from: Central Research Institute for Physics, P.O. Box 49, H-1525 Budapest, Hungary