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Eingeladener Vortrag
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Die ISO-Normen für Druckgasflaschen aus Aluminiumlegierungen erfordern in der Regel eine Wärmebehandlung nach dem Umformungsprozess. Eine solche Wärmebehandlung ist ein kostspieliger Teil bei der Herstellung. Wegen des zunehmenden internationalen Handelsaufkommens müssen Marktüberwachungsbehörden über einfache und zuverlässige Testverfahren zur Überprüfung der ordnungsgemäß durchgeführten Wärmebehandlung an Druckgasflaschen verfügen. In diesem Beitrag wird beispielhaft die unterschiedliche Leistungsfähigkeit der wärmebehandelten und der nicht-wärmebehandelten Gasflaschen gezeigt und verschiedene Verfahren auf ihre Eignung als einfach durchzuführende Stichprobenkontrolle untersucht.
This paper describes experiences and results of experiments with several metallic dusts within the nanometer range. The nano dusts (aluminium, iron, zinc, titanium and copper) were tested in a modified experimental setup for the test apparatus 20 L-sphere (also known as 20-L Siwek Chamber), that enables the test samples to be kept under inert atmospheric conditions nearly until ignition. This setup was already introduced in earlier papers by the authors. It was designed to allow the determination of safety characteristics of nano powders under most critical circumstances (e.g. minimisation of the influence of oxidation before the test itself). Furthermore the influence of passivation on explosion behaviour is investigated and additional tests with deposited dust were carried out to describe the burning behaviour of all dusts. For a better characterisation all samples were tested with a simultaneous thermal analysis (STA). To minimise the influence of oxidation all samples were handled at inert conditions until shortly before ignition or start of the test respectively.
Checking the performance of energy dispersive X-ray spectrometers as well as validation of the results obtained with energy dispersive X-ray spectrometry (EDX) at a scanning electron microscope (SEM) involve the use of (certified) reference and dedicated test materials. This paper gives an overview on the test materials mostly employed by SEM/EDX users and accredited laboratories as well as on those recommended in international standards. The new BAM reference material EDS-CRM, which is currently in the process of certification, is specifically designed for the characterization of EDS systems at a SEM through calibration of the spectrometer efficiency in analytical laboratories in a simple manner. The certification of the spectra by means of a reference EDS is described. The focus is on the traceability of EDS efficiency which is ensured by measurements of the absolute detection efficiency of silicon drift detectors (SDD) and Si(Li) detectors at the laboratory of the PTB using the electron storage ring BESSY II as a primary X-ray source standard. A new test material in development at BAM for testing the performance of an EDS in the energy range below 1 keV is also briefly presented.
Cyanides are among the most important inorganic pollutants to be tested and monitored in environmental compartments. They can be distinguished and determined as free cyanide, weak acid dissociable cyanide or as total cyanide. However, in any case obtained, measurement results are operationally defined referring to the applied analytical method. In 2011, the International Standard ISO 11262 has been published which specifies a normative analytical method for the determination of total cyanide in soil. The objective of the project described in this paper was to provide the first soil reference material (CRM) certified for its mass fraction of total cyanide on the basis of this standard. A total of 12 German laboratories with proven experience in the determination of cyanides in environmental samples participated in the certification study. Measurement results were evaluated in full compliance with the requirements of ISO Guide 35. Taking into account the results of the inter-laboratory comparison as well as the outcome of the homogeneity and stability studies, a certified mass fraction of total cyanide of 21.1 mg/kg and an expanded uncertainty (k=2) of 1.3 mg/kg were assigned to the material. The reference material has been issued as CRM BAM-U114.
We investigate a single-pixel camera (SPC) that relies on non-mechanical scanning with a terahertz (THz) spatial light modulator (SLM) and Compressed Sensing (CS) for image generation. The camera is based on a 350 GHz multiplier source and a Golay cell detector. The SLM consists of a Germanium disc, which is illuminated by a halogen lamp. The light of the lamp is transmitted through a thin-film transistor (TFT) liquid crystal display (LCD). This enables the generation of light patterns on the Germanium disc, which in turn produce reflecting patterns for THz radiation. Using up to 1000 different patterns the pseudo-inverse reconstruction algorithm and the CS algorithm CoSaMP are evaluated with respect to image quality. It is shown that CS allows a reduction of the necessary measurements by a factor of three without compromising the image quality.
This paper shows how Angle-Resolved Scattering can reveal wear on engineered surfaces. The samples studied, three discs made of steel 100Cr6H used in gear wheels in the automotive industry, were assessed after they had undergone ball-on-disc tests. Scattering maps recorded for spatial frequencies from 0.1 µm-1 to 2.7 µm-1 show a contrast inversion around 0.36 µm-1 revealing the wear trace. Besides measurements of rms roughness, where mean values are 20 nm and 24 nm depending on the locations considered, stationarity and isotropy, we demonstrate the ability of the technique to reveal localized wear on this type of surface in a rapid, robust and convenient way. We show that the tool trace is influenced by the load magnitude rather than by the number of oscillation cycles and highlight the key role played by surface roughness in how the sample responds to wear tests.
Abfallgebinde, die im Endlager Konrad eingelagert werden sollen, müssen die Anforderungen und Kriterien erfüllen, die in den Endlagerungsbedingungen (SE-IB-29/08-Rev-1 [1]) und in der Produktkontrolle (SE-IB-30/08-Rev-1) festgelegt sind. Die Qualifizierung der Abfallbehälter erfolgt auf dieser Grundlage in Form von Bauartprüfungen, die von der Bundesanstalt für Materialforschung und -prüfung (BAM) im Auftrag des Bundesamtes für Strahlenschutz (BfS) durchgeführt werden. Darüber hinaus sind die im Hinblick auf Behälterbauartprüfungen relevanten Nebenbestimmungen aus dem Planfeststellungsbeschluss für das Endlager Konrad zu berücksichtigen. Zur besseren Anwendbarkeit werden diese Nebenbestimmungen in die Endlagerungsbedingungen und die Produktkontrolle eingearbeitet. Begleitend ist als Hilfestellung für die Abfallablieferer und Behälterhersteller ein Leitfaden geplant, der praktikable Nachweisstrategien aufzeigt und, soweit erforderlich, Hintergrundinformationen zu den Spezifikationen der Regelwerke liefert. Die BAM ist vom BfS beauftragt, hierfür Vorschläge zu entwickeln und Empfehlungen abzugeben.
Time reversal techniques are used in ocean acoustics, medical imaging, seismology, and non-destructive evaluation to backpropagate recorded signals to the source of origin. We demonstrate experimentally a technique which improves the temporal focus achieved at the source location by utilizing deconvolution. One experiment consists of propagating a signal from a transducer within a concrete block to a single receiver on the surface, and then applying time reversal or deconvolution to focus the energy back at the source location. Another two experiments are run to study the robust nature of deconvolution by investigating the effect of changing the stabilization constant used in the deconvolution and the impact multiple sources have upon deconvolutions focusing abilities. The results show that we are able to generate an improved temporal focus at the source transducer using deconvolution while maintaining the robust nature of time reversal. Additionally, deconvolutions costs are negligible due to it being a preprocessing step to the recorded data. The technique can be applied for detailed investigation of the source mechanisms (e.g. cracks) but also for monitoring purposes.
Given the frequent incidences of Non-Accident Releases (NARs) of hazardous materials from tank cars, there in an increasing interest in transporting hazardous materials in total containment conditions (i.e., no pressure relief devices). However, the ability of tank cars to meet thermal protection requirements provided in the Code of Federal Regulations under conditions of total containment has not been established. Also, the modeling tool commonly used by industry to evaluate thermal protection, AFFTAC, has not been validated under these conditions. The intent of this effort was to evaluate through a series of third-scale fire tests, the ability of tank cars to meet the thermal protection requirements under total containment conditions, and also, to validate AFFTAC for such conditions.
This paper describes the test design and planning effort associated with this research, including the design and evaluation of a fire test setup to simulate a credible, fully engulfing, pool fire that is consistent and repeatable, and the design and hydro-static testing of a third-scale tank specimen. The fire design includes controls on the spatial distribution and temperature variation of the flame temperature, the heat flux, and the radiative balance, to best reflect large liquid hydrocarbon pool fire conditions that may be experienced during derailment scenarios.
Technical background
(2015)
The major components of sector field instruments can be listed as follows and will be described in more detail in the following chapter. (Specific details for the different types of instruments will be given in the corresponding instrumental sections in Chapters 11-17.) The general principle of all mass spectrometers follows ionisation after sample introduction, Separation of the ions according to their mlz ratio and final detection at the detection unit. The transport and Separation of ions follow the principles of ion optics.
Hydrophilic interaction chromatography (HILIC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) were optimised for the direct determination of gadolinium-based contrast agents in tap water. In comparison to our previous work, a new developed zwitterionic HILIC column (ZIC-cHILIC) was used for speciation of Gd-containing contrast agents. The limit of quantification (LOQ) for the five contrast agents Gd-BOPTA, Gd-DPTA-BMA, Gd-BT-DO3A, Gd-DOTA and Gd-DTPA are in the range of 512 ng Gd per litre. Additionally, a new internal standard, Pr-DOTA, was investigated to correct intensity drifts, minor and major changes in the sample volumes and possible matrix effects. With the speciation method described, tap water samples from the area of Berlin were analysed and for the first time, three Gd species, Gd-BT-DO3A, Gd-DOTA and Gd-BOPTA, were found in tap water samples at concentrations of about 10–20 ng Gd per litre. These are the same Gd species which have been previously detected predominantly in surface waters of the Berlin area.
This report focuses on the characterization of CD4 expression level in terms of equivalent number of reference fluorophores (ERF). Twelve different flow cytometer platforms across sixteen laboratories were utilized in this study. As a first step the participants were asked to calibrate the fluorescein isothiocyanate (FITC) channel of each flow cytometer using commercially available calibration standard consisting of five populations of microspheres. Each population had an assigned value of equivalent fluorescein fluorophores (EFF denotes a special case of the generic term ERF with FITC as the reference fluorophore). The EFF values were assigned at the National Institute of Standards and Technology (NIST). A surface-labelled lyophilized cell preparation was provided by the National Institute of Biological Standards and Control (NIBSC), using human peripheral blood mononuclear cells (PBMC) pre-labeled with a FITC conjugated anti-CD4 monoclonal antibody. Three PBMC sample vials, provided to each participant, were used for the CD4 expression analysis. The PBMC are purported to have a fixed number of surface CD4 receptors. On the basis of the microsphere calibration, the EFF value of the PBMC samples was measured to characterize the population average CD4 expression level of the PBMC preparations. Both the results of data analysis performed by each participant and the results of centralized analysis of all participants' raw data are reported. Centralized analysis gave a mean EFF value of 22,300 and an uncertainty of 750, corresponding to 3.3% (level of confidence 68%) of the mean EFF value. The next step will entail the measurement of the ERF values of the lyophilized PBMC stained with labels for other fluorescence channels. The ultimate goal is to show that lyophilized PBMC is a suitable biological reference cell material for multicolor flow cytometry and that it can be used to present multicolor flow cytometry measurements in terms of ABC (antibodies bound per cell) units.
Besonders beim Bauen im Bestand und der Bauwerkserhaltung werden zur Bestimmung des Tragvermögens von historischen, oft unter Denkmalschutz stehenden, natursteinernen Bauteilen Materialkennwerte benötigt. Die üblichen Verfahren mittels Probeentnahme am Objekt und Bestimmung der Kennwerte im Labor bedeuten bei Denkmälern einen massiven Eingriff und sollten vermieden werden. Vermehrt wird daher der Einsatz von zerstörungsfreien Untersuchungsmethoden erforscht und angewendet. Eine dieser Methoden stellt die Ultraschallprüfung dar.
Changes in fuel composition and the introduction of alternative fuels often create problems of degradation in materials. The objective of this research is to study the interaction of the sealing materials FKM, EPDM, CR, CSM, N8R, IIR, VMQ, FVMQ and PA and biofuels such as non-aged and 2 year aged biodiesel (FAME), E1 0 (fuel with 10% ethanol, E85 (fuel with 85% ethanol} and non-aged and 1 year aged 810 (heating oil with 10% biodiesel) in comparison with premium grade fuel without ethanol. Exposure tests were performed with test specimens at 20 °C, 40 oc and 70 oc for 84 days to document the changes in mass, volume and tensile properties. The sealing materials FKM, FVMQ and PA were evaluated as resistant in E10, and FVMQ, VMQ and PA as resistant in E85 at 20 oc and 40 oc. S welling resulted from the high absorption by the elastemers CR, CSM, EPDM, IIR and N8R in comparison to their dissolution in non-aged biodiesei at 40 °C. FKM was still resistant in aged biodiesei at 40 oc but only to a limited degree at 70 °C. The sealing materials CR, CSM, EPDM, IIR and N8R were damaged to a high extent in non-aged and aged 810. Of all the sealing materials, FKM and FVMQ showed high compatibility with these biofuels up to 70 °C.
The aim of this work was to study the interaction between high density polyethylene (HDPE) grades as material for dangeraus goods packagings and biofuels such as E10 (fuel with 10% ethanol), E85 (fuel with 85% ethanol), biodiesei and 810 (heating oil with 10% biodiesel). Jerricans made of two polyethylene grades were filled with these fuels and exposed to temperatures of 20 oc and 40 oc for more than one year. Tensile properlies (tensile strength, breaking elongation and elasticity modulus) and Melt Flow Rate (MFR) were determined, and Fourier Transform Infrared Spectroscopy (FTIR) was used to evaluate changes in the chemical structure.
Measurements of the MFR and tensile properlies of the polyethylene grades after exposure to E1 0, E85 and 810 showed only a slightly damaging influence. A n increase in the peak of 1585 cm·1 for the (C=C) stretching vibrations was visible in the FTIR spectra after immersion tests with E85. A n increase in the MFR with the immersion time of the grades in biodiesei was measured - in parlicular, after one year of exposure. The elasticity modulus of the polyethylene grades was reduced with the immersion time too. The FTIR spectra showed a broadening of the C=O peak of 1740 cm·1 and the appearance of the hydroxyl group at 3500 cm·1.
The tribological profile of alumina (99.7%) mated against rotating disks made in binder-less niobium carbide (NbC) and cobalt-bonded NbC were determined under unidirectional sliding tests (0.1 m/s to 8.0 m/s; 22 °C and 400 °C) as well as in oscillation tests (f = 20 Hz, Δx = 0.2 mm, 2/50/98% rel. humidity, n = 105/106 cycles) under unlubricated (dry) conditions. In addition, the microstructure and mechanical properties of binderless NbC and NbC bonded with 8% cobalt were determined as well. The reason for testing hot-pressed NbC was to avoid side effects generated by sintering additives and/or second phases. The tribological data obtained were benchmarked with different ceramics, cermets and thermally sprayed coatings. NbC and cobalt-bonded NbC exhibited low wear rates under dry sliding associated with high load carrying capacity. The tribological profile established revealed a strong position of NbC bearing materials under tribological considerations and for closed tribo-systems against traditional references, such as WC, Cr3C2 and (Ti,Mo)(C,N).
A sting in the spit: widespread cross-infection of multiple RNA viruses across wild and managed bees
(2015)
1.Declining populations of bee pollinators are a cause of concern, with major repercussions for biodiversity loss and food security. RNA viruses associated with honeybees represent a potential threat to other insect pollinators, but the extent of this threat is poorly understood.
2.This study aims to attain a detailed understanding of the current and ongoing risk of emerging infectious disease (EID) transmission between managed and wild pollinator species across a wide range of RNA viruses.
3.Within a structured large-scale national survey across 26 independent sites, we quantify the prevalence and pathogen loads of multiple RNA viruses in co-occurring managed honeybee (Apis mellifera) and wild bumblebee (Bombus spp.) populations. We then construct models that compare virus prevalence between wild and managed pollinators.
4.Multiple RNA viruses associated with honeybees are widespread in sympatric wild bumblebee populations. Virus prevalence in honeybees is a significant predictor of virus prevalence in bumblebees, but we remain cautious in speculating over the principle direction of pathogen transmission. We demonstrate species-specific differences in prevalence, indicating significant variation in disease susceptibility or tolerance. Pathogen loads within individual bumblebees may be high and in the case of at least one RNA virus, prevalence is higher in wild bumblebees than in managed honeybee populations.
5.Our findings indicate widespread transmission of RNA viruses between managed and wild bee pollinators, pointing to an interconnected network of potential disease pressures within and among pollinator species. In the context of the biodiversity crisis, our study emphasizes the importance of targeting a wide range of pathogens and defining host associations when considering potential drivers of population decline.
The Bronze Age site in the Tollense valley, Germany, has yielded thousands of human and animal bones and a number of archaeological artifacts. Several of the human bones exhibit blunt and sharp force lesions, and the assemblage has been interpreted as representing victims of a large scale conflict. One of the earliest finds is a human humerus with an embedded flint arrowhead. Alleged signs of healing initially reported for this humerus based on clinical CT imaging were interpreted as evidence of an antemortem lesion. The present study, using micro-CT imaging, revealed that the arrowhead lesion in the humerus, contrary to the previous interpretation, shows no signs of healing. The structure previously assumed to represent a sclerotic margin around the wound canal was shown to actually represent compacted trabecular debris. Thus, our re-analysis of the specimen led to a re-classification of the arrow wound as a perimortem lesion. The findings of the present study demonstrate the value of micro-CT imaging as a non-destructive method for obtaining information on the nature of bone lesions and healing reactions critical for the reconstruction of interpersonal conflict scenarios in the past.
The second part of these companion papers mainly researches environmental/operational influences on structural dynamic properties under normal operational conditions during two years, in order to extract a statistical based damage-sensitive indicator for health monitoring of a wind turbine system.
The correlation analyses between experimental identified frequencies, damping values as well as mode shapes and environmental/operational factors such as rotation speed of blades, wind speed, pitch angle, temperature and nacelle direction are presented. It is observed that the frequency estimates are influenced by the nacelle position, the activation of rotor, the rotation speed of blades and the wind speed as well as the temperature. Regarding to the damping estimates, they are mainly associated with variation of the aerodynamic damping due to the increasing wind speed. Besides, the resonance phenomenon is also observed in higher modes. The harmonic frequencies due to blades passing by tower are found and the corresponding damping value decreases. Moreover, the mode shapes in some modes are strongly affected by the position of the nacelle.
Subsequently, two types of simulated damage including the reduction of stiffness in both the rotor blade and the tubular tower are successfully detected by applying the Principal Component Analysis (PCA) based methods to these temperature-sensitive frequency estimates. Comparison of change of the extracted health features indicates that they are more sensitive with the tower damage.
Vibration-based structural health monitoring of a wind turbine system. Part I: Resonance phenomenon
(2015)
This paper is focused on a resonance phenomenon of a wind turbine system in 5 MW class, on the basis of dynamic signals acquired continuously from the tubular tower under normal operational conditions during two years.
Firstly, technique specifications of the wind turbine system are introduced and a finite element model is developed to characterize the structural dynamic properties. The following part describes the continuous dynamic monitoring system integrated with an automated operational modal analysis procedure using the poly-reference Least Squares Complex Frequency domain (p-LSCF) method. Subsequently, variations and mutual relationships of environmental/operational factors such as vibration amplitude, temperature, wind speed, rotation speed of blades, pitch angle and nacelle direction are also presented. Finally, significant resonance is observed due to the fundamental frequency of the tower matching with the harmonic frequency induced by the rotation of three blades. As the rotation speed of rotor approaches to 8 rpm, the vibration amplitude of the tower increases significantly and the corresponding damping value decreases. With the further rising wind velocity, the rotation speed of blades stops increasing and the input energy just contribute to accumulate the vibration amplitude of tower. Such observation indicates the Sommerfeld effect that aggravates the resonance phenomenon. A vibration control device is necessary to minimize the excessive structural responses.
A companion paper will further discuss the environmental/operational effects on dynamic properties of the wind turbine system under the operational conditions.
Aktive Thermografie mit Lockin-Anregung ist ein zerstörungsfreies Prüfverfahren, das insbesondere auch die Prüfung von kohlenstofffaserverstärkten Kunststoffen ermöglicht. Um eine Standardisierung dieses Verfahrens voranzubringen, wurden im Rahmen eines Forschungsprojektes umfangreiche Untersuchungen zur Validierung des Verfahrens durchgeführt. Für die Anregungsmethoden optisch und Ultraschall wurden die wichtigsten Parameter systematisch untersucht. Auf der Auswertungsseite ist dies z.B. der Einfluss der spektralen Empfindlichkeit verschiedener Kamerasysteme. Für die Anregungen sind unter anderem die Einflüsse von Anregungsenergie und Ultraschallfrequenz untersucht worden. Auch Materialparameter, wie der Lagenaufbau bei CFK-Probekörpern, beeinflussen die Ergebnisse stark.
The objective of the present work was to study the impact of Focused Ion Beam (FIB) machining parameters on the thickness of the damaged layer within a thin film PZT. Therefore, different Ga+- ion doses and ion energies were applied to a standard PZT film (80/20 lead zirconium titanate) under two beam incidence angles (90° and 1°). The thicknesses of the corresponding Ga+-implanted layers were then determined by cross-sectional TEM in combination with energy dispersive spectroscopic (EDS) line-scans and correlated with polarisation hysteresis loops. The results show a decrease of Ga+-implanted layer thickness with decreasing inclination angle, whereas ion energy and ion dose could be correlated with gallium concentration in the implanted layers.. Under the most unfavorable conditions the depth of the affected zone was 26 nm, it was only 2 nm for the most favorable conditions.
Laser-induced periodic surface structures (LIPSS, ripples) were processed on steel (X30CrMoN15-1) and titanium (Ti) surfaces by irradiation in air with linear polarized femtosecond laser pulses with a pulse duration of 30 fs at 790 nm wavelength. For the processing of large LIPSS covered surface areas (5 mm × 5 mm), the laser fluence and the spatial spot overlap were optimized in a sample-scanning geometry. The laser-processed surfaces were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). Spatial LIPSS periods between 450 and 600 nm were determined. The nanostructured surface regions were tribologically tested under reciprocal sliding conditions against a 10-mm diameter ball of hardened 100Cr6 steel. Paraffin oil and engine oil were used as lubricants for 1000 sliding cycles at 1 Hz with a normal load of 1.0 N. The corresponding wear tracks were analyzed by OM and SEM. In particular cases, the laser-generated nanostructures endured the tribological treatment. Simultaneously, a significant reduction of the friction coefficient and the wear was observed in the laser-irradiated (LIPSS-covered) areas when compared to the non-irradiated surface. The experiments reveal the potential benefit of laser surface structuring for tribological applications.
The dynamics of the formation of laser-induced periodic surface structures (LIPSS) on fused silica upon irradiation with linearly polarized fs-laser pulses (50 fs pulse duration) is studied by cross-polarized two-color double-fs-pulse experiments. In order to analyze the relevance of temporally distributed energy deposition in the early stage of LIPSS formation, a Mach-Zehnder interferometer was used for generating multiple double-pulse sequences at two different wavelengths (400 and 800 nm). The inter-pulse delay between the individual cross-polarized pulses of each sequence was systematically varied in the sub-ps range and the resulting LIPSS morphologies were characterized by scanning electron microscopy. It is found that the polarization of the first laser pulse arriving to the surface determines the orientation and the periodicity of the LIPSS. These two-color experiments further confirm the importance of the ultrafast energy deposition to the silica surface for LIPSS formation, particularly by the first laser pulse of each sequence. The second laser pulse subsequently reinforces the previously seeded spatial LIPSS characteristics (period, orientation).
The role of mycotoxins in the microbial competition in an ecosystem or on the same host plant is still unclear. Therefore, a laboratory study was conducted to evaluate the influence of mycotoxins on growth and mycotoxin production of Fusarium and Alternaria fungi. Fusarium culmorum Fc13, Fusarium graminearum Fg23 and two Alternaria tenuissima isolates (At18 and At220) were incubated on wheat kernels supplemented with alternariol (AOH), tetramic acid derivates (TeA), deoxynivalenol (DON) and zearalenone (ZEA) in an in vitro test system. Fungal biomass was quantified by determining ergosterol content. Three Fusarium toxins (DON, nivalenol and ZEA) and three Alternaria toxins (AOH, alternariol methyl ether (AME) and altenuene) were analysed by HPLC-MS/MS. If Alternaria strains grew in wheat kernels spiked with Fusarium mycotoxins, their growth rates were moderately increased, their AOH and AME production was enhanced and they were simultaneously capable of degrading the Fusarium mycotoxins DON and ZEA. In contrast, both Fusarium strains behaved quite differently. The growth rate of Fc13 was not distinctly influenced, while Fg23 increased its growth in wheat kernels spiked with AOH. TeA depressed the ergosterol content in Fc13 as well as in Fg23. The DON production of Fc13 was slightly depressed, whereas the ZEA production was significantly increased. In contrast, Fg23 restricted its ZEA production. Both Fusarium strains were not capable of degrading the Alternaria mycotoxin AOH. Mycotoxins might play an important role in the interfungal competitive processes. They influence growth rates and mycotoxin production of the antagonistic combatants. The observed effects between phytopathogenic Alternaria and Fusarium strains and their mycotoxins aid the understanding of the complexity of microbial competitive behaviour in natural environments.
A surface-labeled lyophilized lymphocyte (sLL) preparation has been developed using human peripheral blood mononuclear cells prelabeled with a fluorescein isothiocyanate conjugated anti-CD4 monoclonal antibody. The sLL preparation is intended to be used as a reference material for CD4+ cell counting including the development of higher order reference measurement procedures and has been evaluated in the pilot study CCQM-P102. This study was conducted across 16 laboratories from eight countries to assess the ability of participants to quantify the CD4+ cell count of this reference material and to document cross-laboratory variability plus associated measurement uncertainties. Twelve different flow cytometer platforms were evaluated using a standard protocol that included calibration beads used to obtain quantitative measurements of CD4+ T cell counts. There was good overall cross-platform and counting method agreement with a grand mean of the laboratory calculated means of (301.7 ± 4.9) µL-1 CD4+ cells. Excluding outliers, greater than 90% of participant data agreed within ±15%. A major contribution to variation of sLL CD4+ cell counts was tube to tube variation of the calibration beads, amounting to an uncertainty of 3.6%. Variation due to preparative steps equated to an uncertainty of 2.6%. There was no reduction in variability when data files were centrally reanalyzed. Remaining variation was attributed to instrument specific differences. CD4+ cell counts obtained in CCQM-P102 are in excellent agreement and show the robustness of both the measurements and the data analysis and hence the suitability of sLL as a reference material for interlaboratory comparisons and external quality assessment.
Lightweight granules are mineral, spherical and porous particles with bulk density less than 2000 kg m . New types of lightweight granules are made from masonry -3 rubble as an alternative to the commonly used expanded clay and shale. They are produced in a multistage manufacturing process by thermal or hydrothermal treatment. Studies of the microstructure of the new lightweight granules are very important to optimise the engineering properties with regard to different applications from lightweight concrete to planting substrates and wastewater treatment. Here, the results of porosity and pore structure measurements are presented. Characteristic samples with different bulk densities of both thermally and hydrothermally hardened granules have been analysed by means of various methods.
Die Bestimmung der Haftfestigkeit von Lackierungen, Beschichtungen oder Klebeverbunden ist ein wichtiges Analyseinstrument bei der Beurteilung von entsprechenden Fertigungsabläufen. Unter Verwendung einer neuen Zentrifugentechnologie wurde in einem AiF Forschungsprojekt OKTETT die gesamte Prozesskette Vorbehandlung - Verklebung - Prüfung validiert.
Seit 1829 wird die Farbe Cadmium Gelb in der Malerei verwendet, Cadmium Rot seit 1907. Wegen ihrer Klarheit und Leuchtkraft werden diese Farben von vielen Künstlern geschätzt. Aus Schweden kommt nun der Vorstoß, die Cadmium-Farben zu verbieten, weil das Schwermetall Cadmium zur Verunreinigung landwirtschaftlicher Flächen führen könnte. Sie beraten die Europäische Chemikalienagentur ECHA, die für das Verbotsverfahren zuständig ist. Müssen Künstler in naher Zukunft auf Cadmium Gelb und Cadmium Rot verzichten?
Recently three of the authors of this paper presented analytical solutions for reference loads of plate geometries with semi-elliptical surface cracks subjected to tension, bending, combined tension-bending and biaxial tension. These solutions were shown to provide more accurate crack driving force estimates than the conventional limit load solutions available in the literature, and the method behind them allowed for a wider application range. Within the present paper a methodology for the fracture analysis of thick-wall pressurized pipes using the R6 assessment method and considering both, biaxial and combined tension-bending loading is developed and validated. The analyses are carried out analytically, and the comparison between the predicted critical loads and experimental burst test failure loads shows satisfying agreement, this way demonstrating the potential of the proposed method.
Mit dem generellen Ziel, die Anwendbarkeit und Funktionalität des Verfahrens der stochastischen subspace-basierten Schadensdetektion für Strukturen von Offshore-Windenergieanlagen nachzuweisen, wurden experimentelle und numerische Untersuchungen an einer Laborstruktur sowie anschließend numerische Untersuchungen an einer OWEA-Gründungsstruktur durchgeführt.
Das zugrundeliegende Verfahren verwendet einen Ansatz, in weder modale Kenngrößen noch andere benutzerdefinierte Eingaben erfordert, nachdem einmalig der Referenzzustand aufgenommen wurde. Dabei werden ausschließlich dem Belastungsprozess inhärente stochastische Anregungen der betrachteten Struktur genutzt.
Auf der Basis experimentell erzielter Detektionsergebnisse aus einem Ermüdungsversuch an einer Laborstruktur aus Stahl wurden numerische Modelle und Berechnungsalgorithmen entwickelt und getestet. In einem zweiten Schritt wird diese Analysemethodik auf eine fiktive OWEA-Jacketstruktur realer Größe angewendet. An den simulierten Strukturantworten im Ungeschädigten und geschädigten Zustand wird der Detektionsalgorithmus angewendet, um den Einfluss von Sensorposition und Abtastrate auf die Schadensdetektion festzustellen. Unter Berücksichtigung einzelner vereinfachender Annahmen zeigten die Ergebnisse der Anwendung der vorgestellten Detektionsmethodik an den numerisch erzeugte Antwortdatensätzen eine beachtliche Empfindlichkeit des x2-Testwert basierten Schadensindikators. Obwohl nicht unter allen Umständen in einem frühen Stadium nachweisbar, typische Ermüdungsrisse in Schweißverbindungen von aufgelösten Tragwerken haben ab einer Restbiegesteifigkeit von ca. 80% einen signifikanten und detektierbaren Einfluss auf den Schadensindikator.
Künftige Forschungsaktivitäten in diesem Bereich sollten neben der Erkennung von Schäden auch die Lokalisierung und ggf. auch die Quantifizierung zum Ziel haben. Erforderlich dazu ist die Berücksichtigung und Verarbeitung der strukturellen Parameter und ihrer Sensitivitäten im zugrunde liegenden mathematischen Modell.
Neutron radiography and tomography have been used for a time resolved in situ analysis and a 3D mapping of hydrogen diffusion in iron and steel. Samples were electrochemically charged with hydrogen and afterwards neutron transmission images were taken. Hydrogen diffusion coefficients in duplex stainless steel were determined at 623 K by measuring and comparing the sample's mean intensity with a hydrogen-free reference sample and subsequent normalisation to standards with known hydrogen content. In technical iron and in supermartensitic stainless steel the hydrogen distributions have been investigated. The radiographic images in iron show blisters, cracks and the distribution of molecular hydrogen inside cracks. The analysis of the diffusion behaviour of hydrogen out of a blister illustrates the capabilities of the method with respect to time and spatial resolution. The neutron tomography of supermartensitic tensile stressed samples illustrates the capability to visualise hydrogen distributions three-dimensionally. -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
On a utilisé la radiographie neutronique et la tomographie pour une analyse in situ à résolution temporelle et une cartographie 3D de la diffusion de l'hydrogène dans le fer et l'acier. On a chargé des échantillons par électrochimie avec de l'hydrogène et ensuite on a pris des images par émission de neutrons. On a déterminé les coefficients de diffusion de lhydrogène dans l'acier inoxydable duplex à 623 K en mesurant et en comparant l'intensité moyenne de l'échantillon avec un échantillon de référence sans hydrogène et une normalisation subséquente à des échantillons références à teneur connue en hydrogène. On a examiné la distribution d'hydrogène dans le fer technique et dans l'acier inoxydable supermartensitique. Les images radiographiques du fer montrent des soufflures, des fissures, et la distribution de l'hydrogène moléculaire à l'intérieur des fissures. L'analyse du comportement de diffusion de l'hydrogène hors d'une soufflure illustre les possibilités de la méthode par rapport à la résolution temporelle et spatiale. La tomographie neutronique des échantillons supermartensitiques chargés en traction illustre la capacité de visualiser les distributions d'hydrogène en trois dimensions.
Der Beitrag konzentriert sich auf bildgebende Messverfahren, die der dreidimensionalen Bestimmung mechanischer, geometrischer und kinematischer Parameter von Materialien und Bauteilen dienen. Das sind hier insbesondere die Mehrbildfotogrammetrie sowie die Stereomessverfahren, die auf folgenden physikalisch-optischen Grundlagen beruhen: die zeit- und raumveränderliche Projektion von Lichtstreifensystemen, die Bildkorrelation mittels Grauwertmustern und die Verfolgung kontrastreich applizierter Punkttargets. Letztendlich werden aus den gemessenen Punktkoordinaten unterschiedlicher Dichte und Belastungszustände die gewünschten 3D-Parameter abgeleitet. Hierzu gehören z. B. die Oberflächengestalt und deren Verformung, approximierte 3D-Geometrielemente, veränderliche 6DoF-Starrkörperorientierungen, Vektorverschiebungsfelder, Oberflächendehnung, Koordinaten-Zeit-Funktionen, Geschwindigkeit und Beschleunigung. Diese Kenngrößen sind beispielsweise für die Ermittlung mechanischer Werkstoffeigenschaften und -kennwerte bis hin zur Form- und Verformungsmessung von Bauteilen in gezielt quasi-statisch oder dynamisch beanspruchenden Prüfeinrichtungen wichtig. Vorteilhaft für die praktische Anwendung dieser Verfahren ist insbesondere, dass sie berührungslos arbeiten, kombiniert werden können und skalierbar sind z. B. hinsichtlich Messvolumen, Auflösung, Genauigkeit und Koordinatensystemen der zu bestimmenden 3D-Punktkoordinaten an Materialoberflächen bzw. Komponenten.
Ausgehend von der Beschreibung der messtechnischen Prinzipien dieser Verfahren sollen zwei Anwendungsbeispiele aus dem Bereich der Gefahrgutbehäl-terprüfung im Rahmen von Bauartzulassungen und der normungsbegleitenden Mate-rialforschung den Stand in der Anwendungspraxis aufzeigen und einen Eindruck hinsichtlich der flexiblen Einsatzmöglichkeiten dieser optischen 3D-Verfahren verdeutlichen.
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.
Melamine and melamine resins are widely used as fire-retardants for polymer building materials. Cured melamine systems are used in heat-sensitive items, such as furniture and window frames and sills. In this work, differently cured methylated poly(melamine-co-formaldehyde) (cmPMF) resins were used as fire-retardant coverage for poly(styrene) (PS) and poly(ethylene) (PE) building materials. Such polymer layers should have several tenths of micrometers thickness to produce sufficient fire retardancy. These thick layers were produced by dip-coating. To promote sufficient adhesion of such thick coating to the polyolefin substrates, also in the case of high temperatures occurring at fire exposure, the polymer substrates were firstly coated with a few hundred nanometer thick adhesion-promoting plasma polymer layer. Such thin plasma polymer layers were deposited by low-pressure plasma polymerization of allyl alcohol (ppAAl). It was assumed that the hydroxyl groups of ppAAl interact with the melamine resin; therefore, ppAAl was well suited as adhesion promoter for thick melamine resin coatings. Chemical structure and composition of polymer films were investigated using infrared-attenuated total reflectance and X-ray photoelectron spectroscopy (XPS). Peel strengths of coatings were measured. After peeling, the peeled polymer surfaces were also investigated using optical microscopy and XPS the layers for identification of the locus of peel front propagation. Thermal properties were analyzed using TGA (thermo-gravimetric analyses). Finally, the fire-retardant properties of such thick coated polymers were evaluated by exposure to flames.
The fluorine content of polymer particles labelled with 2,2,2-trifluoroethylamine was reliably quantified with overlapping sensitivity ranges by XPS and solid-state NMR. This provides a first step towards reference materials for the metrological traceability of surface group quantifications. The extension of this concept to fluorescence spectroscopy is illustrated.
Pyrotechnische Gegenstände in Form von Treibladungskartuschen für den Einsatz in der Sprengtechnik
(2015)
Anforderungen, Prüfverfahren und praktische Erprobung von Treibladungskartuschen für den Einsatz in der Sprengtechnik werden erläutert. Nach der europäischen Rechtslage und den europäischen Normen handelt es sich bei derartigen Gegenständen um so genannte steinbrechende Kartuschen, die der EU-Richtlinie 2007/23/EG unterliegen und somit als pyrotechnische Gegenstände behandelt werden.
Ultraschall-Transmissionsmessungen werden seit Jahrzehnten bei der Qualitätssicherung von Betonkonstruktionen eingesetzt. Aus den Wellengeschwindigkeiten lassen sich dynamische Elastizitätsmoduln und – nach lokaler Kalibrierung – auch Druckfestigkeiten ermitteln. Zudem ergeben sich Hinweise auf Risse und andere Materialschwächungen. Der Einsatz erfolgt vor allem im Labor oder an der Bauwerksoberfläche. Neuerdings werden auch Monitoringsysteme mit eingebetteten Sensoren auf Ultraschallbasis erfolgreich getestet. Die Talsperre Eibenstock dient als größte Sperre in Sachsen der Trinkwasserversorgung und dem Hochwasserschutz. Hier wurden während der Bauphase im Jahr 1979 im Fußbereich des Mauerkörpers Ultraschallsensoren eingebracht, die in Verbindung mit einem Messoszilloskop eine Überwachung der Erhärtung des Mauerbetons ermöglichten.
Der für die Sensorauswahl eingesetzte Messstellenumschalter wurde im September 2011 grundlegend instand gesetzt. Danach zeigte sich, dass die eingebetteten Sensoren selbst sowie die Verkabelung auch nach über fünfunddreißig Jahren in einwandfreiem Zustand sind. Eine nunmehr aufgelegte Messserie mit modernem Gerät von über einem Jahr mit ein- bis zweimonatigen Intervallen zeigte, dass die Wellengeschwindigkeit seit der Bauphase noch einmal um gut 10 % zugenommen hat, was für eine erhöhte Druckfestigkeit spricht. Innerhalb des Jahres zeigten sich auch bei Einsatz neuer, sehr sensibler Auswertemethoden (sog. Codawelleninterferometrie) nur geringfügige Schwankungen. Diese waren auch nicht zu erwarten, da sich die Füllhöhe zu den Messzeitpunkten nur gering unterschied, die Temperatur im Bauwerksinneren nur wenig schwankte und der Bauwerkszustand sehr gut ist.
Die Aussagen zur Betongüte sind direkt vergleichbar mit den früheren Mess- und Untersuchungsergebnissen an der Talsperre Gottleuba, die im gleichen Zeitraum errichtet wurde und ebenfalls mit einem Ultraschallsystem ausgerüstet war. Die Experimente zeigten, dass ein Einsatz von Ultraschallsystemen für die Bauwerksüberwachung auch über Jahrzehnte möglich ist. Dies war im vorliegenden Fall nie geplant, aber durch den Einsatz der Mitarbeiter vor Ort und der Herstellerfirma möglich. Bei zukünftigen Systemen ist eine langfristige Planung unter Einbeziehung aller Beteiligten sowie eine Einbindung in Überwachungs- und Wartungspläne notwendig, damit die qualitätsgesichert gewonnen Daten gewinnbringend genutzt werden können.
The investigation of physical properties and chemical composition generates important data for answering cultural-history questions that cannot be solved by historical and philological methods alone. In its individual materiality, each manuscript is the result of a wide variety of influences. The ‘life’ of a manuscript starts with its production, followed by the use and storage of the manuscript, and is finally characterized by its treatment during restoration. Some of these characteristics are still in existence and may provide insights into the production process and history of a manuscript.
Geothermal sources are found to be the most aggressive natural environments for construction materials in terms of corrosion. This study was focused on investigating the suitability of stainless steel UNS S31603 in volcanic areas of geothermal sites Sibayak and Lahendong (Indonesia). Influence of different factors (temperatures up to 175 °C, chloride content up to 1500 mg/L and pH down to 2) was assessed to determine a 'safe operating window' of a power plant and assure the system integrity. Investigations were performed by means of electrochemical methods and long-term exposure tests.
The surfaces of polymeric dialyzer membranes consisting of polysulfone and polyvinylpyrrolidone were investigated regarding the lateral distribution and quantitative surface composition using time-of-flight secondary-ion-mass-spectrometry and x-ray photoelectron spectroscopy. Knowledge of the distribution and composition on the outer surface region is of utmost importance for understanding the biocompatibility of such dialyzer membranes. Both flat membranes and hollow fiber membranes were studied.
Aufgrund von Änderungen des Technischen Regelwerks im Bereich der Betriebssicherheitsverordnung und in den relevanten Normen wurde von der Kommission für Anlagensicherheit (KAS) eine Überarbeitung der Technischen Regel für Anlagensicherheit TRAS 110 in der Fassung von 10. November 2008 für erforderlich gehalten. Nach Beteiligung der Öffentlichkeit und der Bundesländer ist die Neufassung am 6. Januar 2015 im Bundesanzeiger veröffentlicht worden.
The materials in oxyfuel power plant will be subjected to CO2– and SO2–rich gases on the fireside. The oxidation behaviour of two 9–12 % Cr steels T92 and VM12 was studied under dry oxyfuel environment in the temperature range of 580–650 °C for up to 1,000 h. The oxide structure and morphology were analyzed using various experimental techniques. A complex temperature dependence of oxidation rate is observed for both T92 and VM12 whereby the oxidation rate decreased with increasing temperature. This is attributed to increased Cr-enrichment in the inner scale with increasing temperature. T92 and VM12 alloys are also susceptible to carburization in an oxyfuel environment.
The use of open GIS standards offers a broad variety of potential, particularly in the field of data exchange, data storage, and interoperability. GML and CityGML are excellent examples for the ontological description of real world objects by means of an open standard whereas SensorML serves to describe measurements, sensors and measuring platforms. The use of such standards offers not only the possibility of using a common standardised language, but also the use of open service standards. The combination of spatial data and sensor standards in services and service-oriented architectures goes far beyond previous existing solutions on the market and provides a novel platform for monitoring structures. That in fact is far more than a simple data storage model. The methods and models presented in this contribution allow a direct integration of sensor data and its provision through an open standard language. In this case, all the intermediate steps at any time through an open service interface are addressed and may be made available and provided to different actors and stakeholders participating in a construction scenario. The great potential and the added value of such an information system is the permanent availability of measurement and object data and an associated integrated analysis of sensor data in combination with a finite element model (FEM). The automatic derivation of a finite element model from the 3D structure model, the visualisation of FEM, the provision of raw (measurement) data and sensor information for each time of measurement transform the platform into a universal tool in the field of structural monitoring. This contribution introduces the individual components, the standards used and the interaction between the components to an overall system.
Antibodies armed with photosensitizers: from chemical synthesis to photobiological applications
(2015)
Targeting photosensitizers to cancer cells by conjugating them with specific antibodies, able to recognize and bind to tumor-associated antigens, is today one of the most attractive strategies in photodynamic therapy (PDT). This comprehensive review updates on chemical routes available for the preparation of photo-immunoconjugates (PICs), which show dual chemical and biological functionalities: photo-properties of the photosensitizer and the immunoreactivity of the antibody. Moreover, photobiological results obtained with such photo-immunoconjugates using in vitro and in vivo cancer models are also discussed.
In diesem Beitrag präsentieren wir innovative Methoden für die breitbandige und resonanzfreie Messung und Anregung von Ultraschall. Das Messverfahren verwendet eine Kunststofffolie und ein Laser-Vibrometer als breitbandigen und resonanzfreien Empfänger. Im Allgemeinen ermöglicht dieses Verfahren eine präzise Messung der Schallschnelle und des Schalldruckes in beliebigen, für das Laserlicht transparenten Flüssigkeiten und Gasen mit bekannter Dichte und Schallgeschwindigkeit. Das resonanzfreie Senden von Ultraschall basiert auf einem elektro-thermo-akustischen Wandlerprinzip und ermöglicht, im Gegensatz zu herkömmlichen Ultraschallwandlern, die Erzeugung von beliebig geformten akustischen Signalen ohne Resonanzen und ohne Nachschwingen.
Thin poly(acrylic acid) PAA films were deposited by pulsed plasma polymerization on different organic and inorganic substrates. The structureproperty relationships of the deposited acrylic acid polymers were studied in dependence on the monomer pressure by various techniques and probes. The surface and bulk properties of the plasma deposited films were investigated by X-ray photoelectron spectroscopy, attenuated total reflection infrared, and broad band dielectric spectroscopy. The experimental infrared frequencies of PAA films are compared with those predicted from quantum mechanical calculation. The concentration of the COOH groups in the film (stored in ambient air) decreased by about 15 % compared to the as-prepared sample. The plasma deposited PAA probably form a highly branched product. However, the dielectric measurements show that in addition to the hydrogen bonds, self condensation process was able to hinder the localized fluctuation as well. These processes lead to form a cross-linked network polymer film. Nevertheless, a low energy is sufficient to break these processes during heating at atmospheric pressure. Therefore, homogenized samples with free branches (functional group) were obtained after a first heating with structures close to conventional polymerized acrylic acid. Thus, a thermally stable product was obtained.
Revealing the inner secrets of intumescent chars by advanced small scale tests combined with µ-CT
(2015)
Testing of intumescent coatings for Steel is usually done in intermediate scale or even full scale experiments and is hence quite expensive. We developed two complementary small scale tests, simulating fully developed Tire. First is a strongly modified electrical muffle furnace, which is now able to follow the Standard temperature-time curve (according EN 1363-1) for 90 min in a very accurate manner. Düring the experiment backside temperatures are recorded and the growth of the char is observed with a custom made high temperature endoscope. Second is a testing apparatus based on a propane-oxygen-bumer for direct severe flame impingement of coated samples, reaching temperatures far above 1500 °C.
Our small scale samples are coated Steel plates of a size of 75 x 75 x 2 mm3. The structure-propertyrelation between additives, thermal properties and morphology of the char were examined using a well determined series of samples consisting of basic composition mixed with different additives. With the burner-testing-apparatus we studied the behavior of a high performance coating, which shows a transformation of the carbonaceous char into a ceramic foam at temperatures as high as 1600 °C. Nondestructive micro-computed tomography was used to characterize the morphology of the char. According to the structure of the foams we used different analytic methods like cell-detection or wallthickness-analysis. Additional scanning electron and optical microscopy were performed. The combination of the CT-data with the measured backside temperatures of the different samples provides us a deep understanding of the interaction between isolating properties and morphology of intumescent chars.
Microstructure, mechanical properties and corrosion behaviour of WZ21 (%wt.) alloy prepared by a powder metallurgy route from rapidly solidified powders have been studied. Results were compared to those of the same alloy prepared through a conventional route of casting and extrusion. The microstructure of the extruded ingot consisted of α-Mg grains and Mg3Zn3Y2 (W-phase) and LPSO-phase particles located at grain boundaries. Moreover, stacking faults were also observed within α-Mg grains. The alloy processed by the powder metallurgy route exhibited a more homogeneous and finer microstructure, with a grain size of 2 µm. In this case W-phase and Mg24Y5 phase were identified, but not the LPSO-phase. The microstructural refinement induced by the use of rapidly solidified powders strengthened the alloy at room temperature and promoted superplasticity at higher strain rates. Corrosion behaviour in PBS medium evidenced certain physical barrier effect of the almost continuous arrangements of second phases aligned along the extrusion direction in conventionally processed WZ21 alloy, with a stable tendency around 7 mm/year. On the other hand, powder metallurgy processing promoted significant pitting corrosion, inducing accelerated corrosion rate during prolonged immersion times.
Gas cylinders made from composite materials receive growing popularity in applications where light weight is of advantage. At the same time manufacturers are interested in cutting cost and weight through material reduction for better acceptance of a product, e.g. H2-vehicles. This requires a better understanding of safety relevant properties.
The safety determination of current standards is mainly based on the minimum burst pressure of a few specimens. Various research projects were conducted aiming at reducing minimum burst pressure requirements without compromising safety. No satisfying results were found. While looking at reliability aspects it could be concluded, that the minimum burst pressure of unused specimens is not a satisfying criterion for safety during service life.
This paper introduces first ideas for a method to determine one aspect of reliability of composite gas cylinders, employing probabilistic analysis of burst pressures of a sample of specimens. This can create potential for saving material cost while granting a higher safety level than the current method. Additionally, degradation over service time can be assessed.
In Europe the maximum allowable concentration for tributyltin (TBT) compounds in surface water has been regulated by the water framework directive (WFD) and daughter directive that impose a limit of 0.2 ng L-1 in whole water (as tributyltin cation). Despite the large number of different methodologies for the quantification of organotin species developed in the last two decades, standardised analytical methods at required concentration level do not exist. TBT quantification at picogram level requires efficient and accurate sample preparation and preconcentration, and maximum care to avoid blank contamination. To meet the WFD requirement, a method for the quantification of TBT in mineral water at environmental quality standard (EQS) level, based on solid phase extraction (SPE), was developed and optimised. The quantification was done using species-specific isotope dilution (SSID) followed by gas chromatography (GC) coupled to inductively coupled plasma mass spectrometry (ICP–MS). The analytical process was optimised using a design of experiment (DOE) based on a factorial fractionary plan. The DOE allowed to evaluate 3 qualitative factors (type of stationary phase and eluent, phase mass and eluent volume, pH and analyte ethylation procedure) for a total of 13 levels studied, and a sample volume in the range of 250–1000 mL. Four different models fitting the results were defined and evaluated with statistic tools: one of them was selected and optimised to find the best procedural conditions. C18 phase was found to be the best stationary phase for SPE experiments. The 4 solvents tested with C18, the pH and ethylation conditions, the mass of the phases, the volume of the eluents and the sample volume can all be optimal, but depending on their respective combination. For that reason, the equation of the model conceived in this work is a useful decisional tool for the planning of experiments, because it can be applied to predict the TBT mass fraction recovery when the experimental conditions are drawn. This work shows that SPE is a convenient technique for TBT pre-concentration at pico-trace levels and a robust approach: in fact (i) number of different experimental conditions led to satisfactory results and (ii) the participation of two institutes to the experimental work did not impact the developed model.
Im ersten Teil dieses Aufsatzes wurde gezeigt, dass nur ein Teil der für den Deponiebau wesentlichen technischen Eigenschaften in den europäisch harmonisierten Bauproduktnormen DIN EN 13252 und DIN EN 13257, die der CE-Kennzeichnung der Geotextilien (GTX) und geotextilverwandten Produkte (GTP) zugrunde liegen, erfasst werden. Um eine im Wesentlichen vorhandene Gleichwertigkeit der Produkteigenschaften überhaupt abwägen zu können, müssen aber sämtliche relevanten Eigenschaften bekannt sein. Dies erfordert für CE-gekennzeichnete Produkte zusätzliche Prüfungen auf der Grundlage der DepV-Liste der Kriterien und Einwirkmechanismen (Anhang 1, Nummer 2.1.1, DepV). In diesem Teil werden die Tabellen C1 und C2 sowie die Tabelle D aus dem ersten Teil, in denen die Eigenschaften der harmonisierten europäischen Normen (hEN) den Anforderungen der DepV gegenübergestellt wurden, in technischer Hinsicht näher erläutert.
Several fires involving external thermal insulating (ETIC) systems with polystyrene in Germany started an extensive discussion about fire safety of such systems. The Frankfurt fire service started to collect reports about real fire cases which involved ETICS with polystyrene two years ago. This collection shows that especially fires, which started in front of the buildings led to more severe fires of the facades than fires inside the buildings. In several fires the ignition sources were burning waste containers. Three of the real cases are discussed in more detail: a serious fire in Frankfurt on a building site and two fires of apartment buildings, which developed quite differently. Additionally the plastic waste containers, which started several fires are investigated regarding ignitability and heat release rates. The investigation shows that plastic waste containers are very effective as ignition source and that the usual placement directly in front of combustible facades can be a problem for fire safety. Moving these containers and unintentional contact with the facade can lead to damage of the facade coating. These damages were investigated qualitatively and quantitative on a wide collection of buildings. After classifying the damage intermediate scale tests were performed in a modified Single Burning Item (SBI) Test. The damage of the coating was varied as well as the power of the sand bed burner of the SBI apparatus. The damage significantly influenced the fire development on the specimen. In some tests the damaged rendering of the ETIC system collapsed and resulted in a sudden fire growth: after the collapse of the rendering the whole specimen was suddenly on fire. Several effects, which could be seen in the intermediate scale tests correspond to observations which were made in the real cases. As a consequence of the investigations challenges and possible measures to enhance fire safety of ETIC systems are discussed.
Multicomponent flame retardant systems containing aluminum diethylphosphinate in thermoplastic styrene–ethylene–butylene–styrene elastomers are investigated (oxygen index, UL 94, cone calorimeter, and mechanical testing). Solid-state nuclear magnetic resonance, scanning electron microscopy, and elemental analysis illuminate the interactions in the condensed phase. Thermoplastic styrene–ethylene–butylene–styrene elastomers are a challenge for flame retardancy (peak heat release rate at 50 kW m-2 > 2000 kW m-2, oxygen index = 17.2 vol%, no UL-94 horizontal burn rating) since it burns without residue and with a very high effective heat of combustion. Adding aluminum diethylphosphinate results in efficient flame inhibition and improves the reaction to small flame, but it is less effective in the cone calorimeter. Its efficacy levels off for amounts >~25 wt%. As the most promising synergistic system, aluminum diethylphosphinate/melamine polyphosphate was identified, combining the main gas action of aluminum diethylphosphinate with condensed phase mechanisms. The protection layer was further improved with several adjuvants. Keeping the overall flame retardant content at 30 wt%, aluminum diethylphosphinate/melamine polyphosphate/titanium dioxide and aluminum diethylphosphinate/melamine polyphosphate/boehmite were the best approaches. An oxygen index of up to 27 vol% was achieved and a horizontal burn rating in UL 94 with immediate self-extinction; peak heat release rate decreased by up to 85% compared to thermoplastic styrene–ethylene–butylene–styrene elastomers, to <300 kW m-2.
We demonstrate polarity-sensitive orientation mapping of non-centrosymmetric phases by Electron Backscatter Diffraction (EBSD). The method overcomes the restrictions of kinematic orientation determination by EBSD, which is limited to the centro-symmetric Laue-groups according to Friedel's rule. Using polycrystalline GaP as an example, we apply a quantitative pattern matching approach based on simulations using the dynamical theory of electron diffraction. This procedure results in a distinct assignment of the local orientation according to the non-centrosymmetric point group of the crystal structure under investigation.
The approaching CO2 targets have now enforced automotive OEMs to engage R&D efforts also in powertrain to reduce friction, increase lifetime properties, and load carrying capacities of running systems. Martensitic steels such as 36NiCrMoV1-5-7 have a great potential to be used in automotive powertrain applications due to its favorable mechanical properties. In order to realize lightweight strategies, it is essential that steels with improved fracture toughness values and higher annealing temperatures with regard to higher contact pressures and possible thin film coating application be considered. State-of-the-art steels, like 16MnCr5, 21NiCrMo, 30CrMoV9, and 100Cr6 are not able to sustain a further increase in torque or load during operating time as well as annealing effects under higher oil or deposition temperatures. Therefore, the recent research on the slip-rolling resistance, frictional, and wear behavior of steels such as 36NiCrMoV1-5-7, Cronidur 30 (AMS 5898), 20MnCr5 (SAE 4820 or 5120), and 100Cr6H (SAE E52100) showed that possible lean alloying concept alternatives with promising performance characteristics are already available.
The elastic anisotropy caused by the texture in the Nb3Sn filaments of PIT and RRP wires has been calculated by averaging the estimates of Voigt and Reuss, using published Nb3Sn single crystal elastic constants and the Nb3Sn grain orientation distribution determined in both wire types by Electron Backscatter Diffraction. At ambient temperature the calculated Nb3Sn E-moduli in axial direction in the PIT and the RRP wire are 130 GPa and 140 GPa, respectively. The calculated E-moduli are compared with tensile test results obtained for the corresponding wires and extracted filament bundles.
Die beiden in dieser Arbeit dargestellten Beispiele zeigen, dass sich die Low-strain-Pfahlintegritätsprüfung noch über den bisherigen, schon sehr erfolgreichen Stand hinaus entwickeln kann. Der Einsatz von Vibratortechnik und passender mathematischer Methoden bietet das Potential, Prüfungen auch unter bisher nicht lösbaren Randbedingungen durchzuführen. Dazu gehören sehr schlanke Pfähle und Messungen bei hohem Störpegel. Der erhöhte Mess- und Auswerteaufwand ist jedoch im Einzelfall gegenüber dem erzielbaren Erfolg abzugleichen. Apparativ müssen noch Entwicklungsarbeiten geleistet werden, um einen einfachen und zuverlässigen Einsatz in der Praxis zu ermöglichen. Die Messung mit mehreren Sensoren entlang des Pfahls kann schon heute in der Praxis eingesetzt werden. In vielen Fällen lassen sich damit auch Messungen an Pfählen im Bestand durchführen, bei denen die konventionelle Pfahlprüfung aufgrund von überlagernden Signalen aus der aufgehenden Struktur versagt.
Partial discharge in polymeric insulation of high voltage equipment causes cumulative damage that progressively deteriorates the insulation, leading to eventual failure. The electrical detection of related discharge current pulses may be challenged by electromagnetic interference from the environment. In such situations the detection of acoustic emission from partial discharge can greatly enhance its detectability, especially when electromagnetically immune fiber-optic acoustic sensors are used. During experiments involving such fiber-optic sensors that were specifically designed for the detection of partial discharge in elastomeric insulation, an unexpected type of acoustic emission was observed in silicone elastomer specimens with tip–plate electrode configurations and under DC electrical stress. We present and discuss experimental results that indicate space charge injection and subsequent spontaneous dynamical processes as the source of the detected acoustic emission. We use sensitive conventional partial discharge measurement instrumentation to show that the apparent acoustic efficiency of the processes leading to the observed acoustic emission is very high. Acoustic emission triggered by discharge events with individual apparent charge values of only a few femtocoulombs could be detected.
Ober die europäischen Produktnormen für Geokunststoffe (hEN) wird gestritten: Dienen sie nur einem einheitlichen Verfahren der CE-Kennzeichnung oder werden darin alle relevanten geotechnischen Eigenschaften so verbindlich festgelegt, dass darüber hinausgehende nationale Vorschriften ungültig werden? Der Streit wurde durch ein Urteil des Europäischen Gerichtshofs weiter angefacht. Davon noch nicht betroffen ist der Deponiebau. Die Deponie ist ein besonderes Bauwerk, bei dem vor allem abfallrechtliche Regelungen beachtet werden müssen. In der deutschen Deponieverordnung wurde daher eine mit der Europäischen Kommission abgestimmte Gleichwertigkeitsklausel für CE-gekennzeichnete Bauprodukte verankert, die diese Besonderheit berücksichtigt. Wir zeigen, dass das in den hEN festgelegte Eigenschaftsspektrum der Bauprodukte im Wesentlichen nicht gleichwertig zu dem Spektrum ist, das sich aus den Anforderungen der Deponieverordnung ergibt. Die Qualitätssicherung der hEN, die nur eine zertifizierte werkseigene Produktionskontrolle jedoch keine Fremdüberwachung vorsieht, entspricht ebenfalls nicht den Anforderungen der Deponieverordnung. Eine CE-Kennzeichnung kann daher eine BAM-Zulassung nicht gleichwertig ersetzen. Auch für andere geotechnische Anwendungsgebiete gilt, dass die geltenden hEN die Geokunststoffe nicht ausreichend charakterisieren. Die Antwort auf die Frage, wie verbindlich diese mangelhaften hEN werden könnten, ist daher von weitreichender Bedeutung für die gesamte Geotechnik.
The analysis of physical and chemical properties of artefacts provides important data for answering questions that cannot be solved by historical and philological methods alone. In its individual materiality, each manuscript is the result of various influences (e.g. production, storage, restoration, preservation). Given the recent technological developments (e.g. miniaturization of structural units, enlargement of memory capacity), technical diagnostics of art and cultural objects are becoming increasingly sought after in trans-disciplinary research. In this review we present a multi-instrumental approach to the investigation of manuscripts. Several case studies will illuminate our methodology.
Using plastic jerrycans or plastic containers, dangerous goods are transported as air freight in commercial aircrafts. Liquids or gases can escape by leakage or permeation effects from these plastic containers. The German Federal Institute for Materials Research and Testing (BAM) conducted prior research which showed that the lower explosion limit can be reached when transporting dangerous goods in sea-freight containers under normal transportation situations. The presented study is motivated based on these findings. The research objective of this study is to analyze the transportation situation of dangerous goods in cargo compartments of commercial airplanes. The scope of this paper is to present the experimental method used for validating a numerical model for CFD (Computational Fluid Dynamics) simulations and to present some simulation results of the mass transport of dangerous goods in the cargo compartment.
The velocity profiles and the mass transport is calculated using numerical simulations and measured by Laser-Doppler-Anemometry (LDA) experiments. The mock-up is a generic model of a wide-body aircraft lower deck cargo compartment in a 1: 10 scale. Geometry, air exchange rates and inlet as well as outlet flow conditions in the cargo compartment are modeled using realistic boundary conditions. The commercial CFD (Computational Fluid Dynamics) code ANSYS CFX 14 is used for numerical flow simulations applying RANS (Reynolds-Averaged-Navier-Stokes) equations and turbulence models. The turbulence models studied are the renormalization group k-e-model (RNG), the BSL-Reynolds-Stress model (BSL) and the SST-k-co-model by Menter (SST).
The flow measurement with LDA in the mock-up of a cargo compartment proves to be a feasible method for producing data to validate CFD simulations. Qualitative evaluation of the results shows a good overall agreement between numerical and experimental results. The experimental validation indicates that the implemented CFD model is capable of reproducing the flow situation in the model mock-up
In this work the determination of Cd, Cu, Cr, Fe and Sb as organic and inorganic additives in in-house plastic materials (ABS, LDPE) using electrothermal vaporization combined with inductively coupled plasma optical emission spectroscopy is described. The influence of CCl2F2 as gaseous halogenation modifier was investigated. Especially for the carbide forming elements the sensitivity was improved and the memory effects were significantly reduced. Calibration was performed by external calibration and standard addition with aqueous standard solutions added directly into the sample boats. Absolute limits of detection (3s-criterion) range between 0.1 ng (Cd) and 9 ng (Fe) which corresponds to relative values of 0.1 mg kg-1 and 1.6 mg kg-1, respectively, taking 5 mg as typical sample mass. The detection limits are sufficient to monitor the element contents of plastic materials according to European directives such as European directive on the safety of toys. The developed ETV-ICP-OES method allows a fast analysis with a high sample throughput (3 minutes per analysis), low sample consumption and good trueness and precision for the analyzed elements. Sample preparation is reduced to ashing the samples in a muffle furnace. Furthermore, measurements are possible regardless of the chemical form in the additives. For verification the results obtained with the developed method were compared with measurement results of independent methods ICP-MS/OES after digestion. In addition Cd, Cr and Pb were determined in a solid plastic reference material BAM-H010 to confirm the applicability and accuracy of the method.
Commercial platforms consisting of ready-to-use microarrays printed with target-specific DNA probes, a microarray scanner, and software for data analysis are available for different applications in medical diagnostics and food analysis, detecting, e.g., viral and bacteriological DNA sequences. The transfer of these tools from basic research to routine analysis, their broad acceptance in regulated areas, and their use in medical practice requires suitable calibration tools for regular control of instrument performance in addition to internal assay controls. Here, we present the development of a novel assay-adapted calibration slide for a commercialized DNA-based assay platform, consisting of precisely arranged fluorescent areas of various intensities obtained by incorporating different concentrations of a 'green' dye and a 'red' dye in a polymer matrix. These dyes present 'Cy3' and 'Cy5' analogues with improved photostability, chosen based upon their spectroscopic properties closely matching those of common labels for the green and red channel of microarray scanners. This simple tool allows to efficiently and regularly assess and control the performance of the microarray scanner provided with the biochip platform and to compare different scanners. It will be eventually used as fluorescence intensity scale for referencing of assays results and to enhance the overall comparability of diagnostic tests.
Die grundsätzliche Eignung des Verfahrens zur Beurteilung der Passivschichtstabilität konnte mit den vorliegenden Untersuchungen nachgewiesen werden und Grenzen der Anwendbarkeit aufgezeigt werden. Es sind verschiedene Einflüsse in Parameterstudien gezielt untersucht und mit bekannten Methoden zur Beschreibung der Korrosionsbeständigkeit verifiziert worden. Das KorroPad-Prüfverfahren wirkt vorrangig oberflächenspezifisch und eignet sich zur vergleichenden Prüfung von nichtrostenden Stahloberflächen hinsichtlich ihrer Korrosionsbeständigkeit. Der Feuchtlagerung frisch bearbeiteter Oberflächen vor einer KorroPad-Prüfung kommt dabei eine große Bedeutung zu, um eine sichere Differenzierung von korrosionsanfälligen und -beständigen Oberflächen zu gewährleisten.
The automotive industry places significant importance on downsizing components to achieve greater efficiency. The goal of reducing CO2 emissions has led to the development of lightweight materials that are also able to enhance performance. In light of these aspirations, the aim of this study is to characterize two novel, high-performance steels, as well as a 'classical' gear steel for comparison with each other and currently applied materials. The gear steel underwent carburization and subsequent deep freezing treatments in an attempt to yield discrete sample groups with respect to residual austenite. The high-performance steels were heat treated as recommended by their respective manufacturers, and were not carburized. Elemental analyses were conducted by multiple methods to ensure accurate results. Residual austenite contents of the steels and the depth profiles of residual stresses were determined by X-ray diffraction (XRD). Hardness profiles were taken from the testing surfaces into the material core. The carburization of 20MnCr5 led to higher hardness and the greater concentration of carbon in the carburization zone more representative of a hardened SAE E52100, or 100Cr6/102Cr6, than of a non-carburized 20MnCr5. Residual austenite contents ranging from approximately 6–14 vol% were generated, though effectively providing only two, rather than the desired four discrete sample groups. Residual stresses from machining and carburization were measured directly at the sample surface, and from carburization alone below the surface. The high-performance steels fulfilled manufacturer expectations in terms of elemental content, hardness between 50 and 55 HRC and strongly martensitic microstructure character. Finally, slip-rolling endurance testing (T=+120 °C, 10,000,000 cycles, approximately 19 days in a factory fill engine oil) was carried out on all materials, whereby coefficient of friction distributions during testing and wear coefficients after testing were calculated. Testing was performed up to and including P0Mean=1.94 GPa (P0Max=2.91 GPa, FN=2000 N). Ultimately, the non-carburized high-performance steels showed competitive wear performance and better friction behaviour than the carburized 20MnCr5, which has been attributed to their work hardening capability.
This study aims at improving the detection of near-surface defects in magnetizable and conductive specimens by combining the measurements of eddy current, magnetic flux leakage and thermography testing. Different signal processing methods for data normalization are proposed to enable data fusion at the pixel level. These methods are applied to a test specimen which contains 10 variably-sized defects. We quantitatively evaluate the performances of a total of 29 detection methods with respect to false alarm reduction at a fixed level of true positive rate. We report that false positive rate could be reduced from 1.65% down to 0.28% by the best multi-sensor method compared to the best single-sensor performance on the smallest defect, when 50% found flaw pixels are required for successful detection.
In the last years, new approaches for the evaluation of the corrosion resistance of martensitic stainless steels were developed, which allow nearly non-destructive as well as short-term corrosion testing. This work analyzes the sensitive influence of microstructure and surface treatment on the corrosion resistance. The effect of alloy composition and microstructure, which is always present in addition to the influence of various surface treatments will be evaluated and discussed. The corrosion behavior was investigated with conventional evaluation of the pitting potential, electrochemical potentiodynamic reactivation (EPR), electrochemical noise (EN), and the 'KorroPad' (KP) technique. EPR provided information about the passivation ability and the extent of chromium content reduction due to chromium carbide precipitation in the microstructure. The use of EN and KP aims to detect the influence of different surface treatment parameters on the corrosion resistance in a nearly non-destructive way. Furthermore the results shall demonstrate the functionality and convenience of the short-term corrosion test methods EN and KP in order to gain more acceptance within the scientific community. The results will allow the extraction of surface treatment effects on the corrosion behavior of the martensitic stainless steels 1.4116, 1.4034, and 1.4021.
ln den letzten Jahren hat sich gezeigt, dass die Ermittlung des Schwellenwertes DeltaKth nach den bestehenden Standardvorschriften für verschiedene Materialien zu nichtkonservativen Werten führt. Das ergibt sich im Vergleich mit Schwellenwerten, die man mit Anrissen erhält, die hinsichtlich der Ober- und der Unterlast komplett im Druckbereich erzeugt wurden. Dort, wo die Diskrepanz auftritt, verstärkt sie sich mit abnehmendem Spannungsverhältnis. ln der vorliegenden Studie wurden an einem mittel- und einem hochfesten Stahl bei unterschiedlichen Spannungsverhältnissen Schwellenwerte bestimmt. Anwendung fanden die konventionelle Lastabsenkungsmethode nach ASTM-Standard und ein Verfahren, bei dem der Langrissscbwellenwert als Endpunkt der sogenannten Zyklischen R-Kurve erhalten wird. Dieses folgt im Wesentlichen der von Pippan et al. entwickelten Methode, ergänzt diese jedoch durch eine eigene Verfahrensvariante.
In Deutschland fallen aktuell über 5 Mio. Tonnen Hausmüllverbrennungsaschen (HMVA) pro Jahr an. Aus diesen werden nur ca. 8 % Metalle (davon ca. 1 % NE-Metalle) zurückgewonnen. Zur Beurteilung des Wertstoffpotentials werden die HMVA nach standardisierten Vorschriften beprobt, für die Analytik vorbehandelt/vorbereitet/aufgearbeitet und auf ihre Inhaltsstoffe analysiert. Im nachfolgenden Beitrag wird der Schwerpunkt auf die Probenvorbehandlung und -vorbereitung gelegt, wobei der Merkmalstransfer von der Ausgangs-(Feld-)Probe über die Laborprobe und die Prüfprobe bis zur Mess-(Analysen-) Probe am Beispiel von NE-Metallen einer nassaufbereiteten HMVA untersucht wurde. Die Ergebnisse wurden mit Hilfe statistischer Methoden bewertet. Die Ergebnisse zeigen, dass die Verteilung der NE-Metalle in den einzelnen Schritten der Probenbehandlung elementspezifisch ist. Bei Blei ist ein Erhalt der Merkmalsverteilung über alle Behandlungsschritte erkennbar. Bei Kupfer nehmen die Konzentrationen in den aufeinander folgenden Behandlungsschritten deutlich ab. Die Ursache könnte das in der Feinfraktion enthaltene metallische Kupfer mit seinen spezifischen Eigenschaften sein. -------------------------------------------------------------------------------------------------------------------------------------------
More than 5 billion tons of municipal solid waste incineration bottom ashes (MSWI BA) are generated by incineration per year in Germany. Currently only 8 % of metals (of these 1 % are non-ferrous metals) are recovered from MSWI BA. For characterization of recovery potential, MSWI BA samples have to be taken, pre-treated and analyzed according to standardized methods. This manuscript focuses on sample pre-treatment and preparation of a MSWI BA sample aiming to investigate the characteristics transfer over the process of sub-sampling from the original (field) sample to the laboratory sample, test sample until the analytical sample. All results have been evaluated with statistical methods. The results show that influence of each single pre-treatment and preparation step on metal content differs for the individual metals. For lead a conservation of characteristics distribution can be observed, while for copper a continuous decline of solid concentration is observed over all preparation steps. One possible reason may be the fact that copper is mainly contained in the fine fraction as metallic copper with specific properties.
We report on the formation of polymer-stabilized superparamagnetic single-core and multi-core maghemite nanoparticles. The particle formation was carried out by coprecipitation of Fe(II) and Fe(III) sulfate in a continuous aqueous process using a micromixer system. Aggregates containing 50 primary particles with sizes of 2 nm were formed at a reaction temperature of 30 °C. These particles aggregated further with time and were not stable. In contrast, stable single-core particles with a diameter of 7 nm were formed at 80 °C as revealed by small-angle X-ray scattering (SAXS) coupled in-line with the micromixer for particle characterization. X-ray diffraction and TEM confirmed the SAXS results. X-ray absorption near-edge structure spectroscopy (XANES) identified the iron oxide phase as maghemite.
Particle size modality in bi-modal iron oxide suspensions was resolved by exploiting complex ac-susceptibility (ACS), small angle X-ray scattering (SAXS) and photon cross-correlation spectroscopy. To explain dynamic magnetic response of bi-modal suspensions, the Debye model was expanded to a linear superposition form allowing for the contribution of both particle fractions. This modified and adopted model is able to resolve the bi-modal particle size distributions. The SAXS curves of mono- and bi-modal suspensions were fitted well using a Monte Carlo simulation scheme, allowing the detection of bi-modal particle size distributions with high precision.
Resovist® originally developed as a clinical liver contrast agent for Magnetic Resonance Imaging exhibits also an outstanding performance as a tracer in Magnetic Particle Imaging (MPI). In order to study the physical mechanism of the high MPI performance of Resovist®, we applied asymmetric flow fieldflow fractionation (A4F) and static magnetic fractionation (SMF) to separate Resovist® into a set of fractions with defined size classes. As A4F based on an elution method separates MNP according to their hydrodynamic size, SMF fractionates a particle distribution by its magnetic moment. The obtained fractions of both separation techniques were then magnetically characterized by magnetorelaxometry measurements to extract the corresponding effective magnetic anisotropy and hydrodynamic size distribution parameters. Additionally, the MPI performance of each fraction was assessed using magnetic particle spectroscopy. With both separation techniques fractions (normalized to their iron amount) an MPI signal gain of a factor of two could be obtained, even though the distribution of effective anisotropy and hydrodynamic size were significantly different. Relating these findings to the results from magnetic characterization allows for a better understanding of the underlying mechanisms of MPI performance of Resovist®. This knowledge may help to improve the design of novel MPI tracers and development of separation methods.
Shedding light onto the spectra of lime: Raman and luminescence bands of CaO, Ca(OH)2 and CaCO3
(2015)
In microscopy studies of 19th-century cement stone, we found free lime in the form of darkened spherical structures, as they were described in the literature already. When trying to determine their phase composition by Raman spectroscopy, we encountered contradictive assignments in literature spectra of the lime phases CaO, Ca(OH)2 and CaCO3 and observed strong spectral features that have been ignored or erroneously assigned so far. In this study we present Raman spectra of pure lime phases and of a naturally grown calcite crystal, burnt limestone (quick lime, mainly CaO), aged slaked lime putty (mainly Ca(OH)2), and carbonated lime putty (mainly CaCO3). Based on the results, we shed light mainly onto these two questions: (1) Does CaO have a Raman spectrum? (2) Which features in the spectra are luminescence bands that could be (and already have been) misinterpreted as Raman bands? We proof our assignment of luminescence bands in lime phases by using three different laser wavelengths for excitation, and give hypotheses on the origin of the luminescence as well as practical advices on how to identify these misleading features in Raman spectra. This article is mainly addressed to users of Raman spectroscopy in different fields of material analysis who might not be aware of the presence of interfering bands in their spectra.
Thermal ionisation, also known as surface ionisation, was one of the first ionisation techniques developed for mass spectrometry, having been invented as early as 1918. The ionization process, described by the empirically derived “fractionation laws”, is widely understood. Isotope ratio measurements can be achieved with high precision and accuracy. Due to this, thermal ionisation has paved the way for great scientific achievements including: the discovery of new isotopes, the determination of radioactive half-lives and atomic weights of the elements, the accurate determination of the age of the earth and investigations on human society in the past such as mobility and trade. TIMS is still regarded as ‘golden standard’ in isotope ratio measurements. Thus the method is a reference technique that remains at the forefront of isotopic analysis particularly in the fields of metrology. A concise overview is given here of the technical background of thermal ionisation as well as the numerous applications of this technique in earth sciences, industry, metrology, and nuclear forensics.
Measurement strategies
(2015)
Designing an appropriate measurement strategy for a particular analytical question is not always obvious, since a number of factors have to be considered, whereby some of them might be difficult to define. A set of key questions generally precede the experimental design in analytical measurements and help to choose the measurement strategy, which is fit for the intended use – in the particular case of the content of this book – either for quantification, elemental ratio or isotope ratio analyses, accordingly.
Maintenance, Repair and Overhaul (MRO) is acquiring increasing commercial and socio-economic significance. For products and goods with high investment costs and a long lifespan, especially in the sectors of energy and transportation, a considerable portion of commercial profits are generated by after-sales services. In the field of research and development, not enough attention has been paid so far to tasks and approaches involving MRO. The field thus has a limited scientific background, despite a high potential in the business sector for technological and scientific optimization. The challenges and chances of MRO for sustainable enterprises will be explained with reference to the Fraunhofer Innovation Cluster Maintenance, Repair and Overhaul in Energy and Transport. The developments and project results of the four fields of innovation »Cleaning«, »Repair and Overhaul«, »Condition Monitoring and Diagnosis«, as well as »MRO Planning and Digital Assistance« will be explained.
The application of high-strength fine-grained structural steels with yield strengths greater than or equal to 690 MPa expands because of present light weight design trends. The requirements regarding the welded components safety increased due to high loading capacity. This determines a sustainable and economic application as well. However, high welding residual stresses could diminish the components safety, especially due to high restraint conditions in component or repair welds. Therefore, this work is concerned with global and local welding stresses, especially crack-critical welding stresses in the HAZ and while root welding due to the restraint conditions. Restraint intensities of real components were analysed and realised with two different weld tests, alongside two different plate dimensions and steel grades. A comparison of the test results showed several significant effects for heat control and restraint intensity regarding restraint forces and local welding stresses. Among these effects, substantial influences were found for the filler metal selection with partially altered results for root and filler beads. Local stresses of weld seam and HAZ were affected differently.
For the description of (single) crystal orientations, e.g. as measured by electron backscatter diffraction (EBSD) & X-ray diffraction (XRD), Euler angles are still generally used to import and export data. However, because of the lack of standard definitions for the unit cell reference settings and specimen axes, several transformation descriptions exist which produce different sets of Euler angles for the same orientation. There is also no recommended region within the minimal Euler orientation space into which orientations should be placed. This is the reason why different sets of Euler angles for the same orientation are generated by the available software packages for indexing EBSD patterns. These issues are reviewed and addressed.
The influence of crystal symmetry in form of chiral (enantiomorphic) groups is discussed, as well as how multiple, but symmetry-equivalent sets of Euler angles can be reduced in order to deliver a unique orientation description. The Euler coloring algorithms applied to EBSD map data is critically discussed. The specific case of cubic symmetry, especially the effect of the three-fold rotation on the Euler space is investigated in more detail for the highest-symmetric chiral group 432. Recommendations for standard settings of the unit cell to orthogonal coordinate system transformation are given which exploit inherent symmetry.
The formation of laser-induced periodic surface structures (LIPSS) on different materials (silicon, fused silica, quartz) with linearly polarized fs-laser irradiation is studied experimentally. In dielectrics, the importance of transient excitation stages in the LIPSS formation is demonstrated by using (multiple) cross-polarized double-fs-laser-pulse irradiation sequences. A characteristic decrease of the spatial LIPSS periods is observed for double-pulse delays of less than 2 ps along with a characteristic 90°-rotation of the LIPSS orientation.
A two-step separation procedure for the quantification of Pd and Pt in automotive exhaust emissions using isotope dilution mass spectrometry was established using a combination of cation and anion exchange chemistry. AG 50W-X12 was used as cation exchange resin and DGA as weakly basic anion exchange resin. This procedure enabled the effective separation of Pd and Pt from the matrix and from interfering elements. Additionally Pd and Pt were collected in separate chromatographic fractions, which increased the precision of the isotope ratio determination by separate measurements using single collector sector field ICPMS. The analytical procedure was validated by analysing the synthetically prepared samples and the certified reference materials BCR-723 (road dust) and IAEA-450 (algae). For the SI-traceable results complete uncertainty budgets were calculated yielding relatively expanded uncertainties (k = 2) of ≈1% for analyte masses in the ng range. Procedure blanks of 55 pg Pd and 3 pg Pt were obtained. The detection limits were calculated as 12 pg for Pd and 7 pg for Pt. Additionally, Pd and Pt blank levels of different filter materials are presented as well as the first results for automotive exhaust particles collected on cellulose filters.
Beim Abreißen von Flaschenventilen an Atemluftflaschen wird schlagartig sehr viel Energie frei. Im Beitrag wird auf Unfälle im Zusammenhang mit Atemschutzgeräten, welche gerade nicht im Einsatz verwendet werden, eingegangen. Es wird beschrieben, welche die häufigsten Fehler bei der Handhabung solcher Geräte sind, was im schlimmsten Fall passieren kann und an welchen Stellen welche Maßnahmen ergriffen werden sollten, um die Unfallfolgen zu begrenzen bzw. den Unfall zu vermeiden.
Effective cleanup of groundwater contaminated with radionuclides using permeable reactive barriers
(2015)
The mining of natural resources always causes environmental impacts such as land use, large quantities of waste, destruction of habitat, impairment of groundwater regime, and quite possibly contamination of soil, water, or air (Dudka and Adriano 1997). The environmental impact of mining cannot be estimated easily. The concept of total material requirement (TMR) is an attempt to quantify the environmental impact of materials. TMR is the sum of domestic and imported primary natural resources and their hidden flows (Adriaanse et al. 1997). Hidden flows are often not considered in environmental analyses because they are attributed with no cost. However, overburden from mining, earth moving for construction, and soil erosion are major sources of ecological damage. From the mining of minerals to the final products, a number of process steps take place (exploration, mine site development, extraction, milling, washing, concentration, smelting, refining, fabrication), each step being connected to other input flows such as energy or other resources. The hidden flows for metals related to metal ore mining have been investigated by Halada et al. (2001). Table 9.1 lists the data for some metals, together with the data for some other minerals and fuels. The TMR in the United States in the 1990s was between 80 and 100 tonnes per capita; in the European Union (EU-15) approximately 50 tonnes per capita (Bringezu 2002).
Mit einer neuartigen analytischen Zentrifuge können Klebverbindungen, Beschichtungen und Kompositwerkstoffe untersucht werden. Die Idee der Wissenschaftler an der BAM Bundesanstalt für Materialforschung und -prüfung: Die Proben müssen nicht mehr eingespannt, sondern nur noch eingesteckt werden. Durch das einfache Einstecken der Prüfkörper ist eine sehr schnelle Beladung möglich. Zudem können bis zu acht Proben gleichzeitig unter identischen Bedingungen geprüft werden. Konventionelle Zugprüfmaschinen waren und sind nur in der Lage, einen (eingespannten) Probekörper zu testen. Das von BAM-Forschern bereits 2004 zum Patent angemeldete Funktionsprinzip wurde seitdem von der Berliner LUM GmbH als Lizenznehmer zum marktreifen Produkt weiterentwickelt.
Radiologic evaluation techniques are nondestructive testing (NDT) used to detect the bulk of explosives and contraband materials in large objects. As compared to conventional low-energy (<450 key) X-ray imaging, high-energy (>1 MeV) digital X-ray radiography is required for the NOT of large containers because of the need for high penetration through thick materials, sensitivity, and the ability to distinguish between low-and high-Z materials. Mobile, high-energy, and high-resolution radiologic techniques are useful to detect contraband and threat materials in digital radiographic images of containers with complex packing. This paper presents a mobile, high-energy X-ray radiographic technique for the in-field nondestructive inspection of cargo containers. The developed experimental technique consisted of a betatron as a high-energy (7.5 MeV) X-ray source and a high-resolution (400 mu m) matrix detector for the digital X-ray imaging. In order to evaluate the detection efficiency and image quality of the measurement technique, a test specimen was proposed that was made of a 3 mm thick steel container with an inner dimension of 60 x 30 x 40 cm(3) comprising different low-and high-Z materials. Image quality indicators were used to assess the essential image quality parameters such as image basic spatial resolution, effective attenuation coefficient, and signal-to-noise ratio (SNR). Experimental investigations were performed on a 6.1 m sea freight container with mockup dangerous materials in complex packing. Preliminary experimental results showed that the proposed technique was able to distinguish between liquids and solids, as well as detect contraband materials. Furthermore, a remarkable SNR of 400 was achieved in the measured digital X-ray images. The influence of temperature on X-ray radiation dose rate at different X-ray energies was also investigated. Finally, important applications of the proposed technique in the context of maritime security are discussed.
In den Untersuchungen zum Zündvermögen von Filmeffektzündern wurde nachgewiesen, dass diese einen Plastiksprengstoff auf Basis von PETN nicht zu einer detonativen Umsetzung anregen können. Die Erfüllung der grundlegenden Sicherheitsanforderung (ESR) des Anhanges 1 der Richtlinie 2013/29/EG und die Kategorisierung als pyrotechnischer Gegenstand für Theater (T2) kann somit als gegeben angesehen werden, da der verwendete Explosivstoff zur Gruppe der sensibelsten Sprengstoffe (Initiierung mit geringen Zündenergien) gehört. Es wurde weiterhin nachgewiesen, dass der Untemassertest nach DIN EN 13763 Teil 15 aussagekräftige Ergebnisse liefert, welche die Fähigkeit von Filmeffektzündern und vergleichbaren pyrotechnischen Gegenständen bestätigen respektive widerlegen, einen Sekundärsprengstoff zu zünden (eine Detonation zu initiieren).
Für eine allgemeine Einschätzung des Zündvermögens von Filmeffektzündern und vergleichbaren pyrotechnischen Gegenständen ist ein Grenzbereich für ein äquivalentes Zündvermögen in g PETN auf Basis der Experimente mit dem o. g. Unterwassertest bestimmt worden. Filmeffektzünder und vergleichbare pyrotechnische Gegenstände sind nicht in der Lage, einen Sekundärsprengstoff zur Detonation anzuregen, wenn das aus dem Unterwassertest ermittelte äquivalente Zündvermögen unter 0,25 g PETN liegt.
Auswirkungen von Ermüdungsbeanspruchungen auf Struktur und Eigenschaften von Fahrbahndeckenbeton
(2015)
Ausgehend von der Zielsetzung der DFG-Forschergruppe 1498, die Einflüsse auf den AKR-Schädigungsprozess in Fahrbahndecken aus Beton grundlegend zu klären, sind zwei aufeinander aufbauende Untersuchungsschwerpunkte Gegenstand dieses Beitrags. Im ersten Schwerpunkt wurden die prüftechnischen Voraussetzungen für die Charakterisierung der Degradation und damit der Rissbildung im Fahrbahndeckenbeton durch die Vorschädigung infolge von Ermüdungsbeanspruchungen geschaffen. Realisiert wurde dies durch die Implementierung und Optimierung eines Monitoringsystems im zyklischen 4-Punkt-Biegeversuch zur simultanen Erfassung der Rissbildung im großformatigen Schwingbalken. Zusätzlich wurde die Röntgen-3D-Computertomografie für die hochauflösende räumliche quantitative Rissanalyse in den Bohrkernen aus den Schwingbalken ohne und mit Vorschädigung weiterentwickelt. Im zweiten Untersuchungsschwerpunkt wurde mittels vielfältiger Experimente an kleinformatigen Probekörpern aus dem Schwingbalken gezeigt, dass durch die Ermüdungsbeanspruchung die bruchmechanischen Materialkennwerte des Betons zum Teil eine signifikante Veränderung erfahren. Based on the objective of the DFG (German research foundation) funded research group 1498 to clarify the influences on the ASR damage process, this paper deals with two focuses of investigation. In the first focus the technical requirements for the characterisation concerning the degradation and the formation of cracks in concrete pavements by the pre-damage as a result of fatigue loading were created. This was realized by the implementation and the optimisation of a monitoring system in the cyclic four point bending test to capture simultaneously the formation of cracks in the beam under sinusoidal bending load. In addition, the X-ray 3D-computed tomography was enhanced for the high-resolution quantitative spatial crack analysis in the drilling cores extracted of the beam under sinusoidal bending load without and with a pre-damage. Building on the first focus, in the second focus of investigation a significant change of the fracture-mechanical properties of the concrete as a result of fatigue loading has been demonstrated in numerous experiments using small specimens extracted from the beam under sinusoidal bending load.
This paper presents a new X-ray backscatter technique (XBT) for non-destructive imaging of aerospace materials with only a single-sided access. It uses a special twisted slit collimator to inspect the whole object by changing the viewing direction of the X-ray backscatter camera. For the first time, the X-ray backscatter measurements were conducted using high-energy (>500 keV) X-ray sources. Experiments were performed on thick complex structured aluminium components, stringers and honeycomb structures to validate the applicability of the present technique to image small changes in the material properties and also to detect low-density material inclusions. In order to reduce the inspection time from hours to several seconds and to improve the image quality of the X-ray backscatter image, the backscattered signals were measured using a digital detector array with high spatial resolution (200 µm). The influence of the energy of the X-ray source and the slit width of the camera on the X-ray backscatter image were also investigated. In the proposed technique, the whole object is irradiated by an un-collimated X-ray beam resulting in a low image acquisition time of 3 min that facilitates the use of XBT for the real time NDT&E of aerospace materials.
The ground vibrations, which are generated by trains on different tracks, have been calculated by finite-element boundary-element models. The ballasted track is modelled in detail by the finite element method. The infinite soil is modelled by the boundary element method as a homogeneous or layered half-space. The track-soil system is coupled to a simple rigid mass model of the vehicle so that the vehicle-track interaction is completely included. Transfer functions are calculated in frequency domain without and with vehicle-track interaction, the compliance of the track and the mobilities of the soil at different distances from the track. Finally, the ratios between the ground vibration amplitudes with and without mitigation measures are calculated to quantify the effectiveness of the mitigation measures.
Tracks with under-sleeper pads have been investigated in a wide parameter study for the RIVAS project. The main parameters that influence the reduction of ground vibration are the stiffness of the under-sleeper pad, the mass and the width of the sleeper. The softest sleeper pad yields the best reduction of the ground vibration. The influence of the sleeper mass is not so strong, as the characteristic frequency is ruled by the mass of the sleeper and the mass of the wheelset as well.
Behavior of dust/air mixtures is very complex and difficult to predict since it depends on material properties as well as boundary conditions. Without other influences airborne particles deposit due to gravity but the time it takes for total deposition as well as easiness of resurrection depends very much on the specific dust sample and the boundary conditions. It still lacks a complete understanding of all interacting reasons and one approach is using experimentally determined characteristics, one is named dustiness.
Dustiness is the tendency of dust to form clouds and to stay airborne. Dustiness is determined with two basic principles, which are light attenuation and ratio of filled-in and measured mass. Assessment of dustiness of industrial powders has been done for a long time regarding work place safety. Dustiness is used there to determine inhalable fraction and to evaluate health risks. Lately it became interesting in dust explosion protection as well. Dustiness could be used to optimize determination of zones, adaption of venting area and/or for positioning of suppression systems.
Dustiness can be useful in many ways but is not a physical property of dusts, therefore it depends on material properties such as density, particle size distribution, shape and water content as well as boundary conditions or determination method. This makes it very difficult to compare dustiness for different techniques and apparatuses and determination method as well as results should be considered carefully. This work gives an overview of existing standards, recent research and suggests improvements to the new dustiness as proposed for dust explosion protection.
Pd/TiO2 coatings with template-controlled mesopore structure as highly active hydrogenation catalyst
(2015)
Micro-structured reactors offer excellent mass and heat transport capabilities and can therefore sustain very high reaction rates and space–time-yields also for highly exothermic catalytic reactions. However, such high rates cannot be reached when the reactors are coated or filled with conventional catalysts powders. We present a strategy for the direct synthesis of highly active wall-coated supported catalysts via co-deposition of a pore template (here micelles formed from PEO-b-PPO-b-PEO) and a precursors for the metal oxide (TiCl4) along with a compatible precursor for the active metal (PdCl2). The obtained catalytic coatings possess a template-controlled open pore structure and excellent mechanical stability. Moreover, the active metal is highly dispersed and well-distributed across the coating also at high Pd loadings. The corresponding high activity along with rapid mass transfer enabled by the open pore system results in the best space–time-yields in the gas-phase hydrogenation of butadiene reported so far in literature for a supported catalyst.