Filtern
Erscheinungsjahr
Dokumenttyp
Sprache
- Englisch (49) (entfernen)
Schlagworte
- Reliability (5)
- Nanoparticles (3)
- POD (3)
- XPS (3)
- Core-shell (2)
- Core-shell nanoparticles (2)
- Drop test (2)
- Polymers (2)
- SEM (2)
- Abri Pataud (1)
Organisationseinheit der BAM
- 6 Materialchemie (6)
- 6.1 Oberflächen- und Dünnschichtanalyse (5)
- 1 Analytische Chemie; Referenzmaterialien (4)
- 8 Zerstörungsfreie Prüfung (3)
- 8.4 Akustische und elektromagnetische Verfahren (2)
- 1.1 Anorganische Spurenanalytik (1)
- 1.2 Biophotonik (1)
- 1.4 Prozessanalytik (1)
- 1.8 Umweltanalytik (1)
- 3 Gefahrgutumschließungen; Energiespeicher (1)
To properly understand and assess the long-term behaviour of geosynthetic materials it is necessary to investigate the various types of possible degradation mechanims. This includes both chemical and mechanical behaviour, and sometimes even their interactions with one another. Clearly, chemical degradation of geosynthetics depends on the polymer type. For example, polyolefins are vulnerable to oxidation; polyesters are susceptible to hydrolysis; and plasticizers can leach from polyvinyl chloride. This paper describes the concept of these three types of degradation, but focuses on the oxidation of polyolefins since the majority of the geosynthetics is made from this type of polymer. The methods used to predict the lifetime of antioxidants and service life of the geosynthetic material will be illustrated. Furthermore, the influence of temperature, pressure, and ultraviolet light on the service life are also demonstrated. Finally, the current specifications targeting the longevity of different geosynthetics are presented.
Regarding mechanical degradation, the paper mainly focuses upon the creep deformation of geogrids and stress crack resistance (SCR) of polyethylene geomembranes and geopipe. The method to assess stress crack resistance is described, and the microscopic mechanisms that lead to such failure are explained. For creep evaluation, different acceleration tests are presented and their applicability with respect to the different types of polymers is illustrated. In addition, the long-term shear behaviour of geocomposites and geosynthetic clay liners is presented.
Analyser-based imaging expands the performance of X-ray imaging by utilizing not only the absorption properties of X-rays but also the refraction and scatter rejection (extinction) properties. In this study, analyser-based computed tomography has been implemented on imaging an articular cartilage sample, depicting substructural variations, without overlay, at a pixel resolution of 3.6 µm.
Background - It is known that dietary intake of polyunsaturated fatty acids may improve cardiac function. However, relatively high daily doses are required to achieve sufficient cardiac concentrations of beneficial omega‐3 fatty acids. The liver X receptor (LXR) is a nuclear hormone receptor and a crucial regulator of lipid homeostasis in mammals. LXR activation has been shown to endogenously reprogram cellular lipid profiles toward increased polyunsaturated fatty acids levels. Here we studied whether LXR lipid reprogramming occurs in cardiac tissue and exerts cardioprotective actions.
Methods and Results - Male 129SV mice were treated with the LXR agonist AZ876 (20 µmol/kg per day) for 11 days. From day 6, the mice were injected with the nonselective β‐agonist isoproterenol for 4 consecutive days to induce diastolic dysfunction and subendocardial fibrosis while maintaining systolic function. Treatment with isoproterenol led to a marked impairment of global longitudinal strain and the E/e' ratio of transmitral flow to mitral annular velocity, which were both significantly improved by the LXR agonist. Histological examination showed a significant reduction in isoproterenol‐induced subendocardial fibrosis by AZ876. Analysis of the cardiac lipid composition by liquid chromatography‐high resolution mass spectrometry revealed a significant increase in cardiac polyunsaturated fatty acids levels and a significant reduction in saturated fatty acids by AZ876.
Conclusions - The present study provides evidence that the LXR agonist AZ876 prevents subendocardial damage, improves global longitudinal strain and E/e' in a mouse model of isoproterenol‐induced cardiac damage, accompanied by an upregulation of cardiac polyunsaturated fatty acids levels. Cardiac LXR activation and beneficial endogenous cardiac lipid reprogramming may provide a new therapeutic strategy in cardiac disease with diastolic dysfunction.
Superficial white matter (SWM) contains the most cortico-cortical white matter connections in the human brain encompassing the short U-shaped association fibers. Despite its importance for brain connectivity, very little is known about SWM in humans, mainly due to the lack of noninvasive imaging methods. Here, we lay the groundwork for systematic in vivo SWM mapping using ultrahigh resolution 7 T magnetic resonance imaging. Using biophysical modeling informed by quantitative ion beam microscopy on postmortem brain tissue, we demonstrate that MR contrast in SWM is driven by iron and can be linked to the microscopic iron distribution. Higher SWM iron concentrations were observed in U-fiber–rich frontal, temporal, and parietal areas, potentially reflecting high fiber density or late myelination in these areas. Our SWM mapping approach provides the foundation for systematic studies of interindividual differences, plasticity, and pathologies of this crucial structure for cortico-cortical connectivity in humans.
Glasses with compositions of 21Gd2O3-63MoO3-(16-x)B2O3-xTeO2 (mol%) (x= 0, 2, 4, 8) were prepared using a conventional melt quenching technique, and the crystallization behavior of ferroelastic β′-Gd2 MoO4)3 Crystals was examined to clarify the mechanism of self-powdering phenomenon and to design bulk crystallized glasses. It was found that the self-powdering phenomenon appeared significantly during the crystallization at temperatures near the crystallization peak temperature, but the phenomenon is suppressed in the crystallization at temperatures much higher than the glass transition temperature. It was also found that the substitution of TeO2 for B2O3 in the base glasses suppresses the self-powdering phenomenon and consequently bulk crystallized glasses were obtained in the glass with x=8 mol%. The densities at room temperature of the base glasses are d =4.755–4.906 g/cm3, being much higher than the value of d=4.555 g/cm3 for β′-Gd2(MoO4)3 crystal. It is proposed that the stresses in the inside of crystals induced by large density differences (i.e., large molar volume differences) between the glassy phase and crystals might be relaxed effectively in the glasses containing TeO2 with weak TeeO bonds and fragile character.
While structural ceramics usually display a brittle mechanical behavior, their composites may show nonlinearities, mostly due to microcracking. Herein, the stiffness evolution of a sandwich-like laminate of an Al2O3 15%vol. ZrO2 matrix reinforced with Nextel 610 fibers is studied as a function of number of cycles N in tension. The stiffness of the composite degrades with increasing N, indicating microcracking. However, synchrotron X-ray refraction radiography shows that the internal specific surface of such cracks varies differently. A modeling strategy is developed for the calculation of the equivalent stiffness of mixtures (first the matrix and then the sandwich), based on the Voigt and Reuß schemes. The Bruno–Kachanov model is then used to estimate the initial microcrack density in the matrix (due to the thermal expansion mismatch) and the amount of microcracking increase upon cyclic loading. The stiffness in the composite degrades dramatically already after 20 000 cycles but then remains nearly constant. The combination of mechanical testing, quantitative imaging analysis, and modeling provides insights into the damage mechanisms acting: microcrack propagation is more active than microcrack initiation upon cyclic loading, but the second also occurs. This scenario is similar but not equal to previous results on porous and microcracked ceramics.
Investigation of fuel cell materials and liquid water transport by means of synchrotron imaging
(2013)
Synchrotron imaging allows addressing various important issues in fuel cell research, for example water distribution and transport. The water distribution in polymer electrolyte membrane fuel cells (PEMFCs) was observed quasi in-situ directly after operation by means of synchrotron tomography. The 3D data set was compared with the tomogram of a dry cell in order to separate the water distribution from cell materials. Engineered transport pathways realized by perforating holes through the gas diffusion layer (GDL) are a recent approach to optimize water transport and cell performance. For some parameter sets a cell performance increase and an improvement of stabilization have already been proven. We present high resolution investigations of the water distribution in perforated GDLs of operating PEMFCs by means of in-situ synchrotron radiography. The surrounding areas of the holes exhibited a distinct hydrophilic character.
We report the synthesis and spectroscopic characteristics of two different sets of carbon dots (CDs) formed by hydrothermal reaction between citric acid and polyethylenimine (PEI) or 2,3-diaminopyridine (DAP). Although the formation of amide-based species and the presence of citrazinic acid type derivates assumed to be responsible for a blue emission is confirmed for both CDs by elemental analysis, infrared spectroscopy, and mass spectrometry, a higher abundance of sp2-hybridized nitrogen is observed for DAP-based CDs, which causes a red-shift of the n-π* absorption band relative to the one of PEI-based CDs. These CD Systems possess high photoluminescence quantum yields (QY) of ∼40% and ∼48% at neutral pH, demonstrating a possible tuning of the optical properties by the amine precursor. pH-Dependent spectroscopic studies revealed a drop in QY to < 9% (pH ∼ 1) and < 21% (pH ∼ 12) for both types of CDs under acidic and basic conditions. In contrast, significant differences in the pHdependency of the n-π* transitions are found for both CD types which are ascribed to different (de)protonation sequences of the CD-specific fluorophores and functional groups using Zeta potential analysis.
ln this paper a modelling approach is presented to reproduce the mechanical behaviour of sandwich panels via finite element analysis. Two types of panels were investigated in this scope of work. The first sandwich element was a textile reinforced concrete (TRC) panel with cellular lightweight concrete insulation and the second configuration was an ultra-high performances concrete (UHPC) panel with aerated autoclaved concrete insulation. The goal was to obtain a reliable numerical strategy that represents a reasonable compromise in terms of sufficient accuracy of the element characteristics and the computational costs. The results show the possibility of describing the composite action in a full sandwich panel. The achieved modelling approach will later be used for the optimization of TRC and UHPC panels in terms of minimizing the thickness, identifying the number and location of connectors, as well as evaluating varying anchorage Systems.
Core–shell nanoparticles (CSNPs) have become indispensable in various industrial applications. However, their real internal structure usually deviates from an ideal core–shell structure. To control how the particles perform with regard to their specific applications, characterization techniques are required that can distinguish an ideal from a nonideal morphology. In this work, we investigated poly(tetrafluoroethylene)–poly(methyl methacrylate) (PTFE–PMMA) and poly(tetrafluoroethylene)–polystyrene (PTFE–PS) polymer CSNPs with a constant core diameter (45 nm) but varying shell thicknesses (4–50 nm). As confirmed by transmission scanning electron microscopy (T-SEM), the shell completely covers the core for the PTFE–PMMA nanoparticles, while the encapsulation of the core by the shell material is incomplete for the PTFE–PS nanoparticles. X-ray photoelectron spectroscopy (XPS) was applied to determine the shell thickness of the nanoparticles. The software SESSA v2.0 was used to analyze the intensities of the elastic peaks, and the QUASES software package was employed to evaluate the shape of the inelastic background in the XPS survey spectra. For the first time, nanoparticle shell thicknesses are presented, which are exclusively based on the analysis of the XPS inelastic background. Furthermore, principal component analysis (PCA)-assisted time-of-flight secondary-ion mass spectrometry (ToF-SIMS) of the PTFE–PS nanoparticle sample set revealed a systematic variation among the samples and, thus, confirmed the incomplete encapsulation of the core by the shell material. As opposed to that, no variation is observed in the PCA score plots of the PTFE–PMMA nanoparticle sample set. Consequently, the complete coverage of the core by the shell material is proved by ToF-SIMS with a certainty that cannot be achieved by XPS and T-SEM.
This is a corrigendum to the original article "Determining the thickness and completeness of the shell of polymer core-shell nanoparticles by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and transmission scanning electron microscopy" that was published in "The journal of physical chemistry C", vol. 123 (2019), no. 49 pp. 29765-29775.
Most real core-shell nanoparticle (CSNP) samples deviate from an ideal core-shell structure potentially having significant impact on the particle properties. An ideal structure displays a spherical core fully encapsulated by a shell of homogeneous thickness, and all particles in the sample exhibit the same shell thickness. Therefore,
analytical techniques are required that can identify and characterize such deviations.
This study demonstrates that by analysis of the inelastic background in X-ray photoelectron spectroscopy (XPS) survey spectra, the following types of deviations can be identified and quantified: the nonuniformity of the shell thickness within a nanoparticle sample and the incomplete encapsulation of the cores by the shell material. Furthermore, CSNP shell thicknesses and relative coverages can be obtained. These results allow for a quick and straightforward comparison between several batches of a specific CSNP, different coating approaches, and so forth. The presented XPS methodology requires a submonolayer distribution of CSNPs on a substrate.
Poly(tetrafluoroethylene)-poly(methyl methacrylate) and poly(tetrafluoroethylene)-polystyrene polymer CSNPs serve as model systems to demonstrate the applicability of the approach.
A scanning transmission X‐ray microscopy (STXM)‐based methodology is introduced for determining the dimensions (shell thickness, core and total diameter) of core‐shell nanoparticles, which exhibit a strong X‐ray absorption contrast and a well‐defined interface between core and shell material. A low radiation dosage during data acquisition and, therefore, less X‐ray beam‐induced damage of the sample is achieved by recording STXM images only at 2 predetermined energies of maximum Absorption contrast, instead of recording a stack of images across the whole absorption edge.
A model core‐shell nanoparticle, polytetrafluoroethylene (PTFE) cores with polystyrene (PS) shell, is used for demonstration. Near‐edge X‐ray absorption fine structure spectroscopy confirms the significant difference in X‐ray absorption behavior between PTFE and PS. Additionally, because of the insolubility of styrene in PTFE a well‐defined interface between particle core and shell is expected. To validate the STXM results, both the naked PTFE cores as well as the complete core‐shell nanoparticles are examined by scanning electron microscopy (SEM). The introduced STXM‐based methodology yields particle dimensions in agreement with the SEM results and provides additional information such as the position of the particle core, which cannot be extracted from a SEM micrograph.
The paper will give an overview of new methodology for evaluating the
reliability of NDE systems accurately, reliably and efficiently in accordance with the
specific requirements of industrial application. After a review of the substantive
issues from the previous workshops, the go forward guidance from these
interactions is considered.
At the beginning of the reliability analysis, the actual safety demands have to
be defined in order to fit the investigation to the level of risk when the component
would fail. Next, all the essential influencing parameters need to be documented and
transferred to an appropriate design of experiments (DOE) to determine the
reliability in terms of a qualitative assessment for lower risk or in terms of a
quantitative probability of detection (POD) or ROC (Receiver Operating
Characteristics) curves for higher safety demands. A new paradigm is offered to
consider the POD or reliability of the system as a function of the configuration of
input variables and use it for optimisation rather than for a final judgement. An
advantage for the end user is also to sample all single PODs to an integral 'Volume
POD' of a part.
Among the influencing parameters, the human factor is the most important one.
A systematic psychological approach shall help to find out where the bottlenecks are
but most importantly to provide best possible working conditions for the human
inspectors.
Issues that prevent Structural Health Monitoring (SHM) based on Guided Waves (GW) from being a part of today’s monitoring solutions in industry are not all obvious to the scientific community. To uncover and overcome these issues, scientists working on SHM and GW problems joined in an expert committee under the patronage of the German Society for Non-Destructive Testing. An initiated online survey among more than 700 experts and users reveals the hurdles hindering the practical application of GWbased SHM. Firstly, methods for proof of reliability of SHM approaches are missing.
Secondly, detailed understanding of phenomenological described wave-damage interactions is needed. Additionally, there are significant unsolved implementation issues and unsolved problems of signal processing including handling of environmental influences.
To enable substantial proof of reliability without unaffordable experimental effort also efficient simulation tools including realistic damage interaction are needed, enabling the joint use of experimental and simulated data to predict the capabilities of the Monitoring system. Considering these issues, the committee focusses on simulation, signal processing, as well as probability of detection and standardization. In the presented work, recent activities of the expert committee starting with survey results are summarized. An open access data basis of life-like measurements is presented to allow testing and comparison of signal processing and simulation algorithms. Finally, a strategy for efficient proof of reliability increasing the acceptance of SHM in industry and for successful Integration of SHM into real-world engineering structures is proposed.
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.
Traditional earthen structures of cultural value are often damaged by static or dynamic loads. This is usually manifested by the appearance of cracks. All too often these cracks are insufficiently or inappropriately repaired if at all because of lack of knowledge and/or technology. In particular, the behavior of crack repair by grouting poses a challenge in earthen materials and demands specific requirements for the grouting mortar, such as low water content, good water retention, low shrinkage, etc. If dynamic loads, e.g. induced by earthquakes, are expected, the grouting material requires additional specifications such as a compatible strength and modulus of elasticity as well as good adhesion to the earthen materials. The study presents results from the development of a grouting material based on hydraulic lime mortar suitable for the repair of cracks in a variety of earthen building techniques. The goal was to develop a material also compatible with earthen structures exposed to dynamic load. The grouting mortar was designed to be adaptable in strength properties and at the same time to have sufficient robustness for the use on the construction site. First results show a satisfactory performance of the grout concerning fresh and hardened mortar properties as well as injectability. The study is part of our work in the framework of the ongoing project NIKER, funded by the European Commission dealing with improving imovable Cultural Heritage assets against the risk of earthquakes.
Comparative study of the co-assembly behaviour of 3-chloro-4-hydroxy-phenylazo dyes with DTAB
(2023)
The co-assembly of three one-fold negatively charged 3-chloro-4-hydroxy-phenylazo dyes (Yellow, Blue and Red) with the cationic surfactant dodecyltrimethylammoniumbromide (DTAB) was studied to probe dye–DTAB binding stoichiometry and assembly morphology. For each dye, phase separation was observed above a given dye : DTAB ratio with the ratio depending on the dye. While Yellow and DTAB showed liquid/liquid phase separation above Yellow : DTAB = 1 : 1.67, crystalline dye–DTAB complexes were observed for Blue–DTAB and Red–DTAB above Blue : DTAB = 1 : 2.56 and Red : DTAB = 1 : 2.94 respecively. In homogeneous solution, UV/vis spectroscopic investigations suggest stochiometries of Yellow : DTAB = 1 : 2, Blue : DTAB = 1 : 3 and Red : DTAB = 1 : 4. It was concluded, that Yellow exhibits the highest dye : DTAB binding stoichiometry in both, dye–surfactant complexes in the 2-phase region and in solution, whereas the lowest dye : DTAB binding stoichiometry was observed for Red–DTAB in both cases. The observed stoichiometries are inversely correlated to the impact dye addition has on the morphology of DTAB micelles. Generally, addition of dye to DTAB micelles leads to a reduction in spontaneous curvature of these micelles and to the formation of triaxial ellipsoidal or cylindrical micelles from oblate ellipsoidal DTAB micelles. At a DTAB concentration of 30 mM and a dye concentration of 5 mM, this effect was most pronounced for Red and least pronounced for Yellow, whilst Blue showed an intermediate effect.
Poly(butadiene)-b-poly(ethylene oxide) vesicles were successfully loaded with hydrophilic dye Phloxine B. Dye addition during vesicle formation leads to Phloxine B encapsulated inside the water filled vesicle core as well as to freely diffusing dye molecules. The removal of uncapsulated substrate involves time consuming methods like dialysis or harsher methods like ultra filtration or selective precipitation, posing the risk of irreversible sample manipulation. Here used Phloxine B as pH sensitive fluorescence indicator allows the characterization of hydrophilic loading without separation procedure by adjusting the pH value. Additionally membrane blocking efficiency can be studied by time dependent fluorescence measurements. Cryogenic TEM studies showed that the self-assembled structure remained unchanged when the hydrophilic dye was incorporated within the vesicles. Fluorescence microscopy imaging proved the encapsulation of the hydrophilic dye inside the core volume. The combination of fluorescence correlation spectroscopy (FCS) and dynamic light scattering (DLS) measurements as ensemble methods confirmed those results additionally.
Long-term behaviour of geosynthetic drains - excavations on landfills after up to 12 years service
(2002)
Crystallization behavior in different atmospheres (air, Ar, and 7% H2/Ar) of lithium iron phosphate glass (33Li2O33Fe2O31Nb2O5–33P2O5 (LFNP)) powders with different sizes of 2–1000 µm was examined. The crystallization peak temperature (Tp) in Ar and 7% H2/Ar decreased with decreasing the particle size of glass powders, but the value of Tp in air was independent of particle size. The crystallized glass obtained by heating to Tp showed the formation of the α-Li3Fe2(PO4)3 and LiFePO4 crystalline phases. Fe2O3 crystals were formed only in the inside of crystallized glass plates in the heating in air. The crystallization of LiFePO4 was largely enhanced in the particle size of <2 µm during the heating in Ar and 7% H2/Ar atmospheres. The main crystallization mechanism in LFNP glass was found to be surface crystallization. Significant shrinkages were observed for glass compacts (pellets) in the heating in 7% H2/Ar. These results suggest that controlling particle sizes and atmospheres enables the design the morphology of LiFePO4 crystals in LFNP glass.
The paper presents technical details of the drop test performance as well as some experimental results of tests carried out with the Japanese 'Yoyushindo-disposal' waste container for intermediate depth disposal. The tests were accompanied by various metrology to collect data as basis for safety assessment.
Forest fires start mostly in partial combustion. In this paper we present a hydrogen sensor to defect early stages of forest fires. First indoor experiments in a smoke density chamber with wood samples, proved that the sensor produce a strong signal change when the smouldering of wood starts, already before the CO concentration, measured in FTIR spectrometry, exceeds 10 ppm. In outdoor experiments we were able to detect forest fire in a distance of 110 m.
This report describes the methodology of the reliability investigation performed on the ultrasonic
phased array NDT system, developed by SKB in collaboration with Posiva, for inspection of the
canisters for permanent storage of nuclear spent fuel.
The canister is composed of a cast iron insert surrounded by a copper shell. The shell is composed
of the tube and the lid/base which are welded to the tube after the fuel has been place, in the
tube. The manufacturing process of the canister parts and the welding process are described.
Possible defects, which might arise in the canister components during the manufacturing
or in the weld during the welding, are indentified.
The number of real defects in manufactured components have been limited. Therefore the reliability
of the NDT system has been determined using a number of test objects with artifical defects.
The reliability analysis is based on the signal response analysis. The conventional signal response
analysis is adopted and further developed before applied on the modern ultrasonic phased-array
NDT system. The concept of multi-parameter a, where the response of the NDT system is dependent
on more than just one parameter, is introduced. The weakness of use of the peak signal response
in the analysis is demonstrated and integration of the amplitudes in the C-scan is proposed as an
alternative. The calculation of the volume POD, when the part is inspected with more configurations,
is also presented. The reliability analysis is supported by the ultrasonic simulation based on the
point source synthesis method.
In context with Japanese disposal and transport container safety assessment the German Federal Institute for Materials Research and Testing (Bundesanstalt für Materialforschung und -prüfung) per-formed extensive drop test series with prototypes of RAM packages in recent years.
The paper presents two cooperative projects focused on project management, testing performance and experimental results.
In the first project, a full-scale prototype of a package for transport and storage of spent fuel elements with a total mass of 127,000 kg and its reduced-scale model which was similar to the prototype in both geometry and design were drop tested in 9 m and 1 m puncture tests at various drop orientations under regulatory conditions. In context with a corresponding research project the test data was used in combination with numerical methods to investigate the phenomenon of internal cask- content collisions during drop tests. Here, technological gaps between basket or radioactive content and cask body or primary lid can be a reason for significant high dynamic loadings of cask components and its internals due to additional impact interactions in the cask cavity caused by inner relative movement between content and cask. Further investigations were carried out in the field of similarity mechanics comparing experimental drop test data of the full-scale prototype and reduced-scale model in regard to the transferability of package impact response from reduced-scale models to full-scale packages.
In the second project, drop tests with a waste container for intermediate depth disposal were per-formed being contracted by Kobe Steel, Ltd. and a consortium of Japanese electric power plant com-panies. The drop test program comprised three single 8-m drop tests in a specimen’s corner edge orientation. For drop tests according to legal regulations for interim storage or final disposal it is often necessary to use a target which represents the real ground of the storage facility. In such cases the container hits directly onto a well-defined concrete slab on top of the IAEA target. Here, the directly impact target for the drop tests were concrete slabs manufactured in Japan and connected by mortar to the impact pad of the unyielding IAEA target.
This paper presents technical details of the drop test performance as well as some experimental results of tests carried out with the Japanese 'Yoyushindo-Disposal' waste container for intermediate depth disposal. The drop test program comprised three single 8 m drop tests at the specimen's corner edge orientation onto a concrete slab. The slab was connected to the unyielding IAEA target of the BAM's 200 t drop test facility. The three tested specimens had masses between 20 000 and 28 000 kg depending on their content mass. The tests were accompanied by various metrology, such as strain and deceleration measurements, optical three-dimensional deformation methods, leak tightness testing and test installation for potential particle release measurements to collect a set of data for establishing a basis for safety assessment.
Phoenician ivory objects (8th century B.C., Syria) from the collections of the Badisches Landesmuseum, Karlsruhe, Germany, have been studied with full field X-ray fluorescence microimaging, using synchrotron radiation (SR-FF-microXRF). The innovative Color X-ray Camera (CXC), a full-field detection device (SLcam), was used at the X-ray fluorescence beamline of the ANKA synchrotron facility (ANKA-FLUO, KIT, Karlsruhe, Germany) to noninvasively study trace metal distributions at the surface of the archeological ivory objects. The outstanding strength of the imaging technique with the CXC is the capability to record the full XRF spectrum with a spatial resolution of 48 µm on a zone of a size of 11.9 × 12.3 mm² (264 × 264 pixels). For each analyzed region, 69696 spectra were simultaneously recorded. The principal elements detected are P, Ca, and Sr, coming from the ivory material itself; Cu, characteristic of pigments; Fe and Pb, representing sediments or pigments; Mn, revealing deposited soil minerals; Ti, indicating restoration processes or correlated with Fe sediment traces; and Au, linked to a former gilding. This provides essential information for the assessment of the original appearance of the ivory carvings. The determined elemental maps specific of possible pigments are superimposed on one another to visualize their respective distributions and reconstruct the original polychromy and gilding. Reliable hypotheses for the reconstruction of the original polychromy of the carved ivories are postulated on this basis.
Archaeological bone, ivory and antler, as well as objects manufactured from them, are largely studied to extract as much information as possible from these materials. Among others, one key question in archaeology is the exact identification of the material. Even if the identification of different kinds of osseous material seems to be trivial in many cases, it can be a difficult issue when small, heavily carved and more or less altered ancient objects are concerned. This study was focused on the determination of parameters allowing the distinction of archaeological ivory, bone and antler in order to identify the raw material used for the manufacture of prehistoric objects. The high performance of synchrotron radiation (SR) and laboratory-based micro X-ray computed tomography (microCT), providing highly resolved three-dimensional information on the micromorphology, permitted the establishment of such distinctive features of modern references of ivory, antler, land mammal and whale bones: ivory shows characteristic tubular pores with a diameter of about 1 to 2 µm, bone and antler show typical osteon structures. In our measured references, antler shows on average larger and more elongated shaped pores of the osteons compared to terrestrial mammal bone. This feature however depends very much on the original localization of the studied sample within the antler. Whale bones can be distinguished from the other osseous materials by a cancellous, osteoporotic-like structure with irregularly distributed rounded porosities with diameters reaching up to 500 µm. These characteristics have also been tested on determined Palaeolithic fragments, as diagenetic changes during burial have to be considered and may lead to the modification of the parameters established on the basis of modern bone references. In general, the chemical composition of bone objects can change drastically over time while micromorphological features, as evidenced by microCT, seem to be less susceptible to such alterations. In addition, microCT enables the comparison of inner and possibly less altered parts of the objects, and can be considered as completely non-destructive for small mineralised prehistoric objects. In this study, specific morphological features allowing the distinction of ivory and of whale bone from other bone and antler material were determined, even for altered materials dating back to Palaeolithic periods. Thus, we provide, in addition to archaeozoological, chemical and isotopic markers, a new non-destructive tool to identify some raw materials used for the fabrication of osseous objects ranging from recent to prehistoric periods.
The paramagnetic ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate [BMIM][FeCl4] was subject to multiple high-precision thermophysical property measurements under both ambient and high pressure. Density rho(p0,T) / kg m-3 and speed of sound u(p0,T) / m s-1 data at ambient pressure were recorded at temperatures T = (278.15 to 343.16) K using a DSA 5000 M combined vibrating tube densimeter and speed of sound analyser with a standard uncertainty of delta rho(p0,T) = ±0.001 kg m-3 and delta u(p0,T) = ±0.1 m s-1, respectively. High-pressure volumetric (p,rho,T) data were measured on an Anton Paar DMA HPM vibrating tube densimeter at T = (273.16 to 413.15) K and at pressures up to p = 140 MPa with an estimated experimental relative combined average percentage deviation (APD) of delta rho(p,T) / rho(p,T) = ±(0.01 to 0.08) %.
The specific isobaric heat capacity cp(p0,T) / J kg-1 K-1, a caloric property, was determined at T = (273.15 to 413.15) K with an uncertainty delta cp / cp = ±0.5 % using a Perkin Elmer Pyris 1 DSC differential scanning calorimeter. To gain knowledge of transport properties, the dynamic viscosity eta(p0,T) / mPa s at ambient pressure was recorded at T = (275.03 to 413.18) K by an Anton Paar SVM 3000 Stabinger viscometer and additionally an Anton Paar rheometer MCR 302 device with uncertainties of delta eta / eta = ±0.35 % and delta eta / eta = ±1 %, respectively.
The obtained data were first correlated by empirical polynomial equations of state and further processed by the application of classic thermodynamic potentials to determine isothermal compressibility kappa T(p,T) / MPa-1, isobaric thermal expansivity alpha p(p,T) / K-1, thermal pressure coefficient gamma(p,T) / MPa K-1, internal pressure pint(p,T) / MPa, specific heat capacity at constant pressure cp(p,T) / J kg-1 K-1 and at constant volume cv(p,T) / J kg-1 K-1, the difference of isobaric and isochoric heat capacity (cp–cv)(p,T) / J kg-1 K-1, speed of sound u(p,T) / m s-1 and ultimately isentropic exponent kappa s(p,T).
This work extends knowledge about the thermophysical properties of [BMIM][FeCl4] particularly to high temperatures and pressures.
Bispidines for dual imaging
(2014)
The efficient transformation of the hexadentate bispidinol 1 into carbamate derivatives yields functional bispidines enabling convenient functionalization for targeted imaging. The BODIPY-substituted bispidine 3 combines a coordination site for metal ions, such as radioactive 64CuII, with a fluorescent unit. Product 3 was thoroughly characterized by standard analytical methods, single crystal X-ray diffraction, radiolabeling, and photophysical analysis. The luminescence of ligand 3 was found to be strongly dependent on metal ion coordination: CuII quenches the BODIPY fluorescence, whereas NiII and ZnII ions do not affect it. It follows that, in imaging applications with the positron emitter 64CuII, residues of its origin from enriched 64Ni and the decay products 64NiII and 64ZnII, efficiently restore the fluorescence of the ligand. This allows for monitoring of the emitted radiation as well as the fluorescence signal. The stability of the 64CuII–3 complex is investigated by transmetalation experiments with ZnII and NiII, using fluorescence and radioactivity detection, and the results confirm the high stability of 64CuII–3. In addition, metal complexes of ligand 3 with the lanthanide ions TbIII, EuIII, and NdIII are shown to exhibit emission of the BODIPY ligand and the lanthanide ion, thus enabling dual emission detection.
In many industrial sectors, Structural Health Monitoring (SHM) is considered as an addition to Non-Destructive Testing (NDT) that can reduce maintenance effort during lifetime of a technical facility, structural component or vehicle. A large number of SHM methods is based on ultrasonic waves, whose properties change depending on structural health. However, the wide application of SHM systems is limited due to the lack of suitable methods to assess their reliability. The evaluation of the system performance usually refers to the determination of the Probability of Detection (POD) of a test procedure. Up to now, only few limited methods exist to evaluate the POD of SHM systems, which prevent them from being standardised and widely accepted in industry. The biggest hurdle concerning the POD calculation is the large amount of samples needed. A POD analysis requires data from numerous identical structures with integrated SHM systems. Each structure is then damaged at different locations and with various degrees of severity. All of this is connected to high costs. Therefore, one possible way to tackle this problem is to perform computer-aided investigations. In this work, the POD assessment procedure established in NDT according to the Berens model is adapted to guided wave-based SHM systems. The approach implemented here is based on solely computer-aided investigations. After efficient modelling of wave propagation phenomena across an automotive component made of a carbon fibre-reinforced composite, the POD curves are extracted. Finally, the novel concept of a POD map is introduced to look into the effect of damage position on system reliability.
Two fluorescent dyes were incorporated into sol-gel derived SiO2 matrices. The dye was added to SiO2 precursors of different degrees of pre-condensation and the spectroscopic properties of the immobilized dye were measured at various aging and drying stages of the resulting gels. The significant influence of the processing parameters on the spectroscopic properties is manifested in the relative intensity of a second red shifted emission band (550560 nm), which was observed besides the typical coumarin emission band (495 nm). The appearance of this long wavelength emission might be attributed to dye aggregation or to other reactions with the ambient matrix forced by micro porosity phenomena.
The Final Gravettian level (level 2) of the abri Pataud (Dordogne, France) yielded a large assemblage of body ornaments that consists essentially of 85 quite standardized rectangular beads. Some uncertainty remained about the raw material in which these small beads were made: mammoth ivory, reindeer antler or bone? Non-invasive methods were employed in order to determine the raw material. First chemical analyses using microbeam Proton Induced X-ray Emission analysis (microPIXE) did not enable us to conclude definitively. Therefore, synchrotron and laboratory X-ray microtomography (microCT) were applied on eight beads and allowed us to identify ivory for all of them except for one, which shows slightly different morphological features.
Mobility particle size spectrometers (MPSS) belong to the essential instruments in aerosol science that determine the particle number size distribution (PNSD)in the submicrometer size range. Following calibration procedures and target uncertainties against standards and reference instruments are suggested for a complete MPSS quality assurance program: a) calibration of the CPC counting efficiency curve (within 5% for the plateau counting efficiency; within 1 nm for the 50% detection efficiency diameter), b) sizing calibration of the MPSS, using a certified polystyrene latex (PSL) particle size standard at 203 nm (within 3%), c) intercomparison of the PNSD of the MPSS (within 10% and 20% of the dN/dlogDP concentration for the particle size range 20 – 200 nm and 200 to 800 nm, respectively), and d) intercomparison of the integral PNC of the MPSS (within 10%). Furthermore, following measurement uncertainties have been investigated: a) PSL particle size standards in the range from 100-500nm match within 1% after sizing calibration at 203 nm. b) Bipolar diffusion chargers based on the radioactive nuclides Kr85, Am241 and Ni63 and a new ionizer based on corona discharge follow the recommended bipolar charge distribution, while soft X-ray-based charges may alter faster than expected. c) The use of a positive high voltage supply show a 10% better performance than a negative one. d) The intercomparison of the integral PNC of an MPSS against the total number concentration is still within the target uncertainty at an ambient pressure of approximately 500 hPa.
Bulk metallic glasses (BMG) are amorphous metal alloys known for their unique physical and mechanical properties. In the present study, the formation of femtosecond (fs) laser-induced periodic surface structures (LIPSS) on the Zr-based BMGs Zr46Cu46Al8, Zr61Cu25Al12Ti2, Zr52.5Cu17.9Al10Ni14.6Ti5 (Vit105) and Zr57Cu15.4Al10Ni12.6Nb5 (Vit106) was investigated as a function of their different chemical composition. For this purpose, LIPSS were generated on the sample surfaces in an air environment by fs-laser irradiation (λ = 1025 nm, τ = 300 fs, frep = 100 kHz). The surface topography was characterized by scanning electron microscopy and atomic force microscopy. Moreover, the impact of LIPSS formation on the structure and chemical surface composition was analyzed before and after fs-laser irradiation by X-ray diffraction and X-ray photoelectron spectroscopy as well as by transmission electron microscopy in combination with energy dispersive X-ray spectroscopy. Despite the different chemical composition of the investigated BMGs, the fs-laser irradiation resulted in almost similar properties of the generated LIPSS patterns. In the case of Zr61Cu25Al12Ti2, Vit105 and Vit106, the surface analysis revealed the preservation of the amorphous state of the materials during fs-laser irradiation. The study demonstrated the presence of a native oxide layer on all pristine BMGs. In addition, fs-laser irradiation results in the formation of laser-induced oxide layers of larger thickness consisting of an amorphous ZrAlCu-oxide. The precise laser-structuring of BMG surfaces on the nanoscale provides a versatile alternative to thermoplastic forming of BMG surfaces and is of particular interest for the engineering of functional material surfaces.