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The first hard X-ray beamline at BESSY II will be installed by BAM and PTB at a superconducting 7 T wavelength shifter. The main optical elements of the beamline are a Double-Multilayer-Monochromator and a Double-Crystal-Monochromator. The two devices can be used separately or in-line. Main applications of monochromatic radiation with photon energies up to 50 keV are X-ray fluorescence analysis, micro-computed tomography, X-ray topography, detector calibration and reflectometry. Calculable undispersed radiation up to 200 keV will be available for radiometric applications.
The precursor [FeIII(L)Cl] (LH2 = N,N'-bis(2'-hydroxy-3'-X-benzyliden)-1,6-diamino-3-N-hexane) is a high-spin (S = 5/2) complex (with X = -CH3, -O-CH3). This precursor is combined with the bridging unit [SnIV(CN)4] to yield star-shaped pentanuclear clusters, [(L-X-FeIII)4Sn(CN)4]Cl4 57Fe-Mössbauer, 119mSn-Mössbauer, and ESR spectroscopy are used to study our samples. For X = -CH3 the 57Fe-Mössbauer data show a multiple spin transition between iron(III) in the high-spin and low-spin state. Changing the functional group from X = -CH3 to X = -O-CH3 turns the switchability off.
he main objective of the nPSize project is to improve the measurement capabilities for nanoparticle size based on both measurement methods traceable to SI units and new reference materials. Two basic approaches have been used in order to develop measurement procedures resulting in traceable results of the nanoparticle size distribution: physical modelling for the methods used in the project (TSEM, SEM, AFM and SAXS) and machine learning.
Physical modelling: In this part, the physical models associated with different shape measurements for the techniques TSEM, SEM, AFM and SAXS have been collected and further developed with the aim to simulate the resulting signal as measured by the individual methods. Uncertainties and traceability associated with each model were investigated and evaluated. In the following, the progress on these physical models is reported for each individual method.
Machine Learning modelling: The aim of this part is to use machine learning to enable automatic measurement of nanoparticle shape from expert a-priori information only. No physical model will be used as a-priori information in this task.
The accuracy and traceability of the size results obtained by each technique will be analyzed and compared with the physical modelling. A machine learning database will then be used to create automatic detection algorithms.
The study described in this paper was conducted in the framework of the European nPSize project (EMPIR program) with the main objective of proposing new reference certified nanomaterials for the market in order to improve the reliability and traceability of nanoparticle size measurements. For this purpose, bimodal populations as well as complexly shaped nanoparticles (bipyramids, cubes, and rods) were synthesized. An inter-laboratory comparison was organized for comparing the size measurements of the selected nanoparticle samples performed with electron microscopy (TEM, SEM, and TSEM), scanning probe microscopy (AFM), or small-angle X-ray scattering (SAXS). The results demonstrate good consistency of the measured size by the different techniques in cases where special care was taken for sample preparation, instrument calibration, and the clear definition of the measurand. For each characterization method, the calibration process is described and a semi-quantitative table grouping the main error sources is proposed for estimating the uncertainties associated with the measurements. Regarding microscopy-based techniques applied to complexly shaped nanoparticles, data dispersion can be observed when the size measurements are affected by the orientation of the nanoparticles on the substrate. For the most complex materials, hybrid approaches combining several complementary techniques were tested, with the outcome being that the reliability of the size results was improved.
Electron paramagnetic resonance (EPR) of Fe3+ ions in Al2O3 is studied in powder samples prepared by different routes and/or modified by thermal or mechanical treatments, with different doping levels and grain sizes. The measurements are performed in various frequency bands (S, X, K, Q and W) and with bimodal detection in X-band. Simulations of the spectra are achieved with a code designed for computing EPR powder spectra described by any spin Hamiltonian including second-, fourth-and sixth-order ZFS terms (S ? 7/2). The linewidths, intensities and lineshapes are accounted for. The lineshape is Gaussian at low Fe3+ concentration whereas it is Lorentzian for higher concentration. The linewidths are interpreted as the superimposition of three main contributions: intrinsic linewidth, dipolar broadening and broadening due to lattice imperfections. The latter is tentatively interpreted in terms of quadrupolar spin Hamiltonian parameter distributions treated using first-order perturbation theory. Whatever the sample, only the b22 spin Hamiltonian parameter is found to be distributed around a mean zero value which corresponds to rhombic distortions. Angle and bond length distributions are tentatively extracted from the b22 distributions which gives some insight into the local order around the spin probe in relation to the preparation and treatment of the samples.
Kunststoffe sind wichtige Werkstoffe und heutzutage aus Haushalt und Wirtschaft nicht mehr wegzudenken. Seit Anfang der 1970er-Jahre wird das Vorkommen von Kunststoffpartikeln in Küstengewässern beschrieben. Inzwischen ist Mikroplastik nicht nur im marinen Bereich, sondern auch in weiteren Umweltkompartimenten, Biota und technischen Einrichtungen der Wasserwirtschaft nachgewiesen worden, in dieser Arbeit wird ein Überblick über das Vorkommen von Mikroplastik in der aquatischen Umwelt und ersten bekannten Auswirkungen gegeben. Darüber hinaus werden die aktuellen Untersuchungsverfahren von Probenahme, Probenaufbereitung und Analytik betrachtet und offene fragen diskutiert. Zentral erscheint in diesem Zusammenhang die Entwicklung einer harmonisierten medienübergreifenden Untersuchungsmethodik, die eine Auswertung relevanter Stoffströme ermöglicht und auf notwendige Bewertungskonzepte abgestimmt ist.
Monitoring the ingestion of microplastics is challenging and suitable detection techniques are insufficiently used. Thus, misidentifying natural for synthetic microfibres cannot be avoided. As part of a framework to monitor the ingestion of microplastics in eelpout, this short report addresses the accurate identification of microfibres. We show that, following visual inspections, putatively synthetic microfibres are indeed of natural origin, as ascertained by spectrometric analyses. Consequently, we call for an inclusion of spectroscopic techniques in standardized microplastic monitoring schemes.
Avoiding aerial microfibre contamination of environmental samples is essential for reliable analyses when it comes to the detection of ubiquitous microplastics. Almost all laboratories have contamination problems which are largely unavoidable without investments in clean-air devices. Therefore, our study supplies an approach to assess background microfibre contamination of samples in the laboratory under particle-free air conditions. We tested aerial contamination of samples indoor, in a mobile laboratory, within a laboratory fume hood and on a clean bench with particles filtration during the examining process of a fish. The used clean bench reduced aerial microfibre contamination in our laboratory by 96.5%. This highlights the value of suitable clean-air devices for valid microplastic pollution data. Our results indicate, that pollution levels by microfibres have been overestimated and actual pollution levels may be many times lower. Accordingly, such clean-air devices are recommended for microplastic laboratory applications in future research work to significantly lower error rate
Europium 1,3-di(thienyl)propane-1,3-diones with outstanding properties for temperature sensing
(2015)
The synthesis of novel Eu complexes with 1,3-di(thienyl)propane-1,3-diones as ligands as well as their luminescence properties in different polymers are reported. The new temperature sensitive paints (TSPs) exhibit not only exceptional high temperature sensitivity over a wide range of temperatures but are also characterized by negligible pressure sensitivity and marked photostability. This is why they are outstandingly suitable for applications, e.g. in aerodynamics and hydrodynamics.
A strongly fluorescent organic semiconducting polymer doped with a highly
temperature dependent fluorescent europium(III) complex is converted into a
nanosized material that is capable of optically sensing temperature (T) in the
range from 0 to 50 °C via two-photon excitation at 720 nm. The nanosensors
are prepared from a blue-fluorescent polyfluorene that acts as both a lightharvesting
antenna (to capture two-photon energy) and an energy donor in a
fluorescence resonance energy transfer (FRET) system. The photonic energy
absorbed by the polymer is transferred to the T-sensitive red-luminescent
europium complex contained in the nanoparticles. The close spatial proximity
of the donor and the acceptor warrants efficient FRET. A poly(ethylene glycol)-
co-poly(propylene oxide) block copolymer is also added to render the particles
biocompatible. It is shown that T can be calculated from a) the intensity of
the luminescence of the europium complex, b) the ratio of the intensities of
the red and blue luminescence, or c) the T-dependent luminescence lifetime
of the Eu(III) complex.