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Organisationseinheit der BAM
Samples of different three-dimensionally preserved fossil plants (Medullosa sp., Dadoxylon sp., Calamodendron striatum, Psaronius sp.) from the Lower Permian petrified forest of Chemnitz were examined with regard to their chemical composition and structural order. Raman spectroscopy and cathodoluminescence microscopy are shown to be powerful tools for such investigations.
Silicified wood from ChemnitzHilbersdorf generally shows yellow cathodoluminescence (CL) of the cell walls and only weak yellow-brownish CL of the cell lumina. By time-resolved cathodoluminescence spectroscopy, a secondary mineralisation of hydrothermal origin was recognized. The latter is shown by short-lived blue CL at the cell walls extinguishing the yellow signal. Therefore, after the primary silicification step a secondary mineralisation step initiated by hydrothermal processes, seems to have taken place at probably slightly higher temperatures. The resulting silica matrix consists of phanerocrystalline and microcrystalline a-quartz as well as microcrystalline moganite, both partially associated with iron oxides.
Dadoxylon sp. is a prominent example for parallel permineralisation by a-quartz and fluorspar, which is outstanding for the Chemnitz Petrified Forest. CL on this samples shows parallel silicification and fluoritisation, followed by infiltration of iron oxides.
Permineralised samples show very low percentage of original organic remains. The seed fern Medullosa, for example, shows dispersed carbon, which is mainly restricted to the centres of the typical star-shaped vascular bundles. Raman spectroscopy revealed that these carbonaceous particles are of an anthracite structure. For experimental confirmation coal samples of different rank, especially anthracite from different geological times and localities, were studied by means of Raman spectroscopy. The remaining pith of the vascular bundles is white-coloured and consists of a-quartz and moganite, whereas surrounding tracheides exhibit white and reddish coloured parts. The reddish parts, mainly found in the rays, additionally contain a-Fe2O3 and Fe3O4 among the SiO2 polymorphs of a-quartz and moganite. Sometimes iron oxides could have dominated permineralisation processes as the peak intensities of distinct parts of the samples suggest.
Metalloligands L1 and L2 consisting of directional bis(terpyridine)ruthenium(II) units and bipyridine moieties were constructed by amide formation. From these metalloligands two Ru–Pt heterobimetallic complexes 1 and 2 were derived by a building-block method by means of platination with [PtCl2(dmso)2]. Both bimetallic complexes 1 and 2 feature metal-to-ligand charge transfer (MLCT) absorptions, and emission occurs at room temperature in fluid solution from ³MLCT(Ru) states in all cases. Energy transfer from platinum to ruthenium is observed in 2 but not in 1 (light harvesting). The one-electron-reduced species [1] and [2] were prepared by reduction of 1 and 2 with decamethylcobaltocene. EPR spectra and DFT calculations reveal that the spin density is localized at the tpy–CO/Ru (tpy = terpyridine) site in [1], whereas it is centered at bpy–CO/Pt (bpy = 2,2'-bipyridine) in [2]. Efficient photoinduced electron transfer from triethanolamine to 1 and 2 is feasible by excitation at 500 nm [MLCT(Ru)].
In order to investigate molecular recognition on surfaces, an azide-functionalized monolayer was deposited on gold. The monolayer was characterized by X-ray photoelectron spectroscopy (XPS) and angle-resolved near-edge X-ray absorption fine structure (NEXAFS) experiments and the decomposition of the azide upon irradiation with X-ray beams was investigated. Subsequently, various alkyne-functionalized host and guest molecules were attached to the azide by 1,3-dipolar cycloaddition. These modified surfaces and their host–guest chemistry were analysed by XPS and angle-resolved NEXAFS. The reversibility of guest binding was shown for one example as a proof of principle.
Der vorliegende Bericht gibt einen Überblick über die neue Normenreihe DIN EN 15947 über „Pyrotechnische Gegenstände - Feuerwerkskörper, Kategorien 1, 2 und 3". Es werden der Anwendungsbereich aufgezeigt und wesentliche Änderungen im Vergleich zu der zurückgezogenen und ersetzten Normenreihe DIN EN 14035 über „Feuerwerkskörper" vorgestellt. Die Normenreihe DIN EN 15947 besteht aus den fünf Teilen „Begriffe", „Kategorien und Feuerwerkstypen", „Mindestanforderungen an die Kennzeichnung", „Prüfverfahren" und „Anforderungen an Konstruktion und Funktion" und wurde im Dezember 2010 veröffentlicht.
Der vorliegende Bericht gibt einen Überblick über die Normenreihen DIN EN 16261 'Pyrotechnische Gegenstände - Feuerwerkskörper, Kategorie 4' und DIN EN 16256 'Pyrotechnische Gegenstände - Pyrotechnische Gegenstände für Bühne und Theater'. Neben der Vorstellung der jeweiligen Anwendungsbereiche werden die wesentlichen Anforderungen an Konstruktion, Funktion und Kennzeichnung aufgezeigt. Des Weiteren werden die Prüf- und Bewertungsmethoden dieser pyrotechnischen Gegenstände dargestellt und miteinander verglichen. Die Normenreihe DIN EN 16261 besteht aus 4 Teilen 'Begriffe', 'Anforderungen', 'Prüfverfahren' und 'Mindestanforderungen an die Kennzeichnung und Gebrauchsanweisung'. Die Normenreihe DIN EN 16256 ist strukturell vergleichbar aufgebaut enthält aber im Vergleich zur Normenreihe DIN EN 16261 einen weiteren Teil zur Unterscheidung der Kategorien T1 und T2.
This application note presents how EnviroESCA can be used to analyze bacterial samples under near ambient pressure conditions in various states of hydration using different levels of humidity. Such investigations of bacterial cell wall surfaces in their hydrated state are essential for studying biological interfaces at work.
The use of innovative near-ambient pressure (NAP-)XPS instrumentation allows the detailed analysis of irregularly-surfaced biofilms. NAP-XPS enables the surface analysis of bacterial samples in their natural hydrated state without complex sample preparation techniques such as freeze-drying or fast-freezing, which are needed for XPS analysis in ultrahigh vacuum.
The work focuses on the potential of structural and chemical examinations by scanning electron microscopy based methods for archaeometric studies on ceramics. Achieved by a single preparation technique (polished block sections), the feasibility and benefits of electron backscatter diffraction are demonstrated as case studies using polychrome examples of pre-Columbian pottery (Wari, Moche and Cajamarca). Elemental and phase maps allow for separate consideration of clay and temper. Identification of mineral phases and intergrowths of temper particles provide information for clarifying clay procurement and firing techniques with respect to local versus non-local pottery to enlighten trade relations, technological transfer and shared heritage of pre-Columbian cultures.