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Scan-free grazing-emission X-ray fluorescence spectroscopy (GEXRF) is an established technique for the investigation of the elemental depth-profiles of various samples. Recently it has been applied to investigating structured nanosamples in the tender X-ray range. However, lighter elements such as oxygen, nitrogen or carbon cannot be efficiently investigated in this energy range, because of the ineffective excitation. Moreover, common CCD detectors are not able to discriminate between fluorescence lines below 1 keV. Oxygen and nitrogen are important components of insulation and passivation layers, for example, in silicon oxide or silicon nitride. In this work, scan-free GEXRF is applied in proof-of-concept measurements for the investigation of lateral ordered 2D nanostructures in the soft X-ray range. The sample investigated is a Si3N4 lamellar grating, which represents 2D periodic nanostructures as used in the semiconductor industry. The emerging two-dimensional fluorescence patterns are recorded with a CMOS detector. To this end, energy-dispersive spectra are obtained via single-photon event evaluation. In this way, spatial and therefore angular information is obtained, while discrimination between different photon energies is enabled. The results are compared to calculations of the sample model performed by a Maxwell solver based on the finite-elements method. A first measurement is carried out at the UE56-2 PGM-2 beamline at the BESSY II synchrotron radiation facility to demonstrate the feasibility of the method in the soft X-ray range. Furthermore, a laser-produced plasma source (LPP) is utilized to investigate the feasibility of this technique in the laboratory. The results from the BESSY II measurements are in good agreement with the simulations and prove the applicability of scan-free GEXRF in the soft X-ray range for quality control and process engineering of 2D nanostructures. The LPP results illustrate the chances and challenges concerning a transfer of the methodology to the laboratory.

In early 2020, the COVID-19 virus rapidly spread around world and forced people to significantly adjust their lives. Lockdowns compelled society to digitalise, thereby substantially increasing the processing of personal information. On 17 June 2020, when South Africa faced the pandemic’s “first wave”, key provisions of the Protection of Personal Information Act 4 of 2013 (POPIA) were enacted from 1 July 2020, further enabling full enforcement from 1 July 2021. This first South African omnibus data protection act unleashes legal uncertainty due to the highly abstract formulation of its provisions. Considering the recent increase of processing of personal information, the “young” POPIA is under pressure to evolve quickly to mitigate liability risks for responsible parties and at the same time provide a reliable and predictable framework ensuring the protection of protection of personal information.

Fire‐gilding is a historic technique for the application of golden layers on a number of different base materials utilizing a gold amalgam. This technique leaves a significant amount of Hg in the golden layer, giving archeometrists a reliable indicator to identify fire‐gildings. Recent findings on presumably fire‐gilded objects have shown in several cases significantly lower Hg content than previously studied objects. This prompted a synchrotron‐based X‐ray fluorescence investigation into the Hg distribution along the material–gilding interface, as well as a series of measurements regarding the Hg content development in fire‐gilded samples during artificial aging. This work presents findings on laboratory‐prepared fire‐gildings, indicating an Hg enrichment at the interface of fire‐gilded silver samples. Notably, such an enrichment is missing in fire‐gilded copper samples. Further, it is confirmed that fire‐gilded layers typically do not undercut an Hg bulk content of 5%. In this light, it seems improbable that ancient samples that contain

An increasing demand for products and services in the aviation industry is attended by a rising demand for aircraft engines. This requires an increased productivity combined with highest quality and safety standards. In this paper, a new approach of material defect detection is presented which is based on force and acoustic-emission measurements during machining processes. Representative synthetic defects in titanium alloy Ti6246 were investigated. In order to use scale effects, the experiments were conducted in micro-milling processes. This approach could be used for an automated, non-destructive evaluation of the manufactured components in the future and thus for reducing testing effort and related auxiliary times.

Taking advantage of the superior cutter axial stiffness, plunge milling provides a higher material removal rate in rough milling for components with deep cavities. Tool wear depending on cutting parameters of radial cutting width, axial cutting depth, step interval, feedrate, and spindle speed has been studied by several researchers. For a more comprehensive understanding of the wear mechanism, this study investigates the influences of tool engagement angle and tool geometry on tool wear based on multiple sets of machining tests. The development of tool wear during plunge milling is monitored. Results show that tool wear of insert with large engagement angle mainly exists on minor edge, which is caused by increased tool deflection. When the radial distance equals to tool radius, optimal engagement angle can be achieved while considering both tool life and machining efficiency. The experimental results show that tool life of insert with rake angle of 22° is 6.5% higher than rake angle of 15°. Smaller corner radius has positive influences on tool life improvement. Surprisingly, tool life of insert without cutting edge chamfer is 3.6 times than insert with cutting edge chamfer. The best tool geometric parameters of plunge insert can then be identified among a variety of inserts. This work is useful for cutting tool producers and manufacturers to optimize tool geometry and machining parameters.

The development of thin-film thermoelectric applications in sensing and energy harvesting can benefit largely from suitable deposition methods for earth-abundant materials. In this study, p-type copper oxide thin films have been prepared on soda lime silicate glass by direct current (DC) magnetron sputtering at room temperature from a pure copper metallic target in an argon atmosphere, followed by subsequent annealing steps at 300 °C under various atmospheres, namely air (CuO:air), nitrogen (CuO:N) and oxygen (CuO:O). The resultant films have been studied to understand the influence of various annealing atmospheres on the structural, spectroscopic and thermoelectric properties. X-ray diffraction (XRD) patterns of the films showed reflexes that could be assigned to those of crystalline CuO with a thin mixed Cu(I)Cu(II) oxide, which was also observed by near edge X-ray absorption fine structure spectroscopy (NEXAFS). The positive Seebeck coefficient (S) reached values of up to 204 μV K−1, confirming the p-type behavior of the films. Annealing under oxygen provided a significant improvement in the electrical conductivity up to 50 S m−1, resulting in a power factor of 2 μW m−1 K−2. The results reveal the interplay between the intrinsic composition and the thermoelectric performance of mixed copper oxide thin films, which can be finely adjusted by simply varying the annealing atmosphere.

Novel technical developments are a source for new business models and, at the same time, a challenge for legal systems and in particular data protection laws. A fundamental challenge in this respect is the delocalisation of data proceedings enabled by modern technologies. In addition, most cases related to such new data driven business models contain foreign elements. From a data protection perspective this raises numerous legal questions, related to the territorial scope of data protection instruments and their relation to the established rules and principles of private international law. The European General Data Protection Regulation (GDPR) addresses the delocalisation with extra-territorial scope rules, but the discussion on how those provisions are embedded in the legal framework of private international law has only started. This article will address those questions in context of the GDPR and the South African Protection of Personal Information Act (POPIA) from a comparative perspective. After a brief overview of the GDPR, the requirements of the territorial scope rules of Articles 3(1) and (2) GDPR will be examined. Thereafter, the doctrinal classification of these rules within the established categories of private international law and the question of whether a choice of the applicable data protection law is permitted within the legal framework of the EU will be investigated. In conclusion, the article examines the territorial scope of the POPIA and provides recommendations for an improvement of the existing rules de lege ferenda.

The use of tools with chamfered cutting edges is an essential part of high performance cutting (HPC) as a rough milling process strategy for manufacturing structural components in the aerospace industry. Due to an interaction between the chamfer and the undulated workpiece surface, tool vibrations can be damped allowing high depths of cut without the occurrence of harmful dynamic effects. Hence, a significant increase in efficiency is possible. As a result of process damping, the stability boundary predicted by linear stability analysis provided for instance by analytical or geometric physically-based simulations will generally underestimate the experimentally determined one. Consequently, the object of this procedure, namely to reduce the number of test runs until sufficient process parameter values are determined, could not be met. Therefore, the damping effect induced by chamfered tools was analysed in this paper. It is shown that the use of chamfered cutting edges leads to a significant limitation of chatter amplitudes when exceeding the stability limit. The strength of this effect depends on the cutting speed and the engagement situation, which influence the intensity and number of interactions between the chamfer and the workpiece surface and, thus, the resulting process damping. Moreover, a dynamic process damping model presented in the literature was chosen and implemented in a geometric physically-based milling simulation. An evaluation of its validity points out the challenges regarding the simulation of process damping.

The runout of milling tools results in uneven effective tooth radii and affects the occurrence of tool wear in machining processes. The load and, thus, the specific wear of teeth with increased effective radii is higher. In processes with small undeformed chip thicknesses, e.g., the finishing of titanium alloys, the runout error could even be greater than the undeformed chip thickness. In this case, at least one cutting edge does not remove any material. In this paper, the influence of the runout on wear effects is analyzed for an exemplary finishing process using cutting force measurements and a geometric physically-based process simulation.

Sozialfirmen müssen soziale Orientierung und unternehmerische Führung vereinen. Eine Studie bei Schweizer Sozialfirmen zeigte, dass eine ausgeprägt unternehmerische und marktorientierte Führung mit einer überdurchschnittlichen Zielerreichung verbunden ist. Das gilt auch für Organisationen, die sich völlig dem «Not-for-profit»-Gedanken verpflichten fühlen und kein Interesse an finanziellen Überschüssen haben. Prof. Dr. Markus Gmür, Direktor des Verbandsmanagement Instituts der Universität Freiburg (Schweiz), und der Sozialunternehmer Jonas Baumann-Fuchs stellen die Ergebnisse vor und zeigen mögliche Konsequenzen auf.

This work reports laboratory angle resolved measurements with the goal of establishing laboratory techniques to obtain a more complete idea of the intralayer composition of multilayer samples. While X-ray reflectometry is a widely available technique for the characterization of multilayer samples, angle resolved XRF measurements (grazing emission/incidence X-ray fluorescence) are usually performed at synchrotron radiation facilities. With the development of efficient laboratory spectrometers and evaluation algorithms for angle resolved measurements, these methods become suited for routine measurements and screening. We present two laboratory spectrometers which make quantitative non-destructive elemental depth profiling feasible. For reasons of comparison a validation sample, a nickel–carbon multilayer sample, is measured with both setups and additional information on krypton contamination and its distribution is retrieved. Additionally, the first application for the characterization of multilayer structures with sub-nanometer layer thicknesses is shown.

In sheet-bulk metal forming (SBMF), the high geometric complexity of workpieces and differently dimensioned functional elements within the forming tool can lead to an insufficient form filling of cavities. One approach to optimize the SBMF process are functional surface structures, which can be used to influence the contact situation between forming tool and workpiece. Therefore, the aim of this project was to create defined surface structures with specific roughness properties on forming tools for SBMF. This was realized by a milling process with intentionally induced regenerative tool vibrations and high-feed (HF) milling. For this purpose, the basics for a simulation environment were first created, within which the process parameter settings for the generation of the occurring vibration patterns were defined. The effects of the surface structures thus generated were investigated and validated both theoretically and experimentally. The results were transferred to free-form surfaces with application for the SBMF tools. Subsequently, the proceedings were extended for HF milling which proved to be advantageous to micro milling in terms of tool life, process efficiency and control. The application of quasi-deterministic patterns with different tribological properties of the surface depending on the desired local surface characteristics and the process parameter values was enabled.

Plunge milling has been proven to be an efficient strategy for machining of pockets with deep cavities and difficult-to-cut material. Previous work generates the plunge toolpath mainly by controlling the radial cutting width within the given value. However, uneven tool engagement angles may lead to excessive tool load and tool load fluctuations, which has a negative influence on tool life. In this study, a universal plunge milling toolpath generation method is proposed to improve tool life by decreasing the maximum tool engagement angle. A series of concentric circles with constant radius increment is utilized to generate a toolpath with constant cutting radial depth. Center of the concentric circle is determined based on the pocket contour. New detailed algorithms to generate plunge toolpath for basic cases have been developed. An automatic pocket subdivision algorithm has been developed by dividing the pocket into several subregions that are easy to be machined. Without loss of generality, the method is applicable for both open and closed pockets. It also works for pockets with and without islands inside. The method is implemented and verified successfully by machining experiments. The results provide strong evidence that the proposed method can reduce the maximum engagement angle over the entire toolpath and thus improve the tool life.

Efficient soft X-ray spectroscopy in the laboratory is still a challenging task. Here, we report on new toroidal multilayer optics designed and applied with the laser-produced plasma (LPP) source of the Berlin Laboratory for innovative X-ray technologies. The optics are described and characterized, and the application of the updated source to scanning-free grazing emission X-ray fluorescence is demonstrated on thermoelectric gold-doped copper oxide nanofilms. The comparison with synchrotron measurements allows estimating a flux on the sample of approximately 7.5 × 109 photons/s in the 1 keV range on a 100 µm × 100 µm spot, emphasizing the suitability of the updated LPP source for the application in photon hungry experiments. K.B. is most grateful for the scholarship from the International Max-Planck Research School at the Fritz Haber Institute. J.B. would like to thank the Excellence Initiative of the Deutsche Forschungsgemeinschaft for financial support.

Lightweight components with low wall thickness continue to gain technological and economic importance in aerospace and other industries. Thereby, the low wall thickness and thus high compliance of such workpieces may cause the occurrence of undesired vibrations under the characteristic load of machining operations. The suppression of dynamic effects such as regenerative chatter represents a central requirement for milling operations with regard to the achievable component qualities and process efficiency. Certain approaches base on the application of support structures or damping elements, which are attached to the workpiece. After processing the thin-walled components, however, the added structures have to be removed in elaborate processes. In this paper, a new approach is presented which is focusing on an optimised process stabilisation method using cryogenic solidified coolant. By injecting coolant emulsion into the CO2 snow jet and applying it specifically to thin-walled workpieces, stiffening support structures were generated and damping elements attached. The ice layer melts off after machining and returns into the lubricant circuit with no need for conditioning or additional filtering. Modal tests and machining experiments demonstrated the applicability of the presented approach and a significant decrease of the dynamic compliance and deflection of the workpiece during milling operations.

Geometric physically-based simulation systems can be used for analyzing and optimizing complex milling processes, for example in the automotive or aerospace industry, where the surface quality and process efficiency are limited due to chatter vibrations. Process simulations using tool models based on the constructive solid geometry (CSG) technique allow the analysis of process forces, tool deflections, and surface location errors resulting from five-axis machining operations. However, modeling complex tool shapes and effects like runout is difficult using CSG models due to the increasing complexity of the shape descriptions. Therefore, a point-based method for modeling the rotating tool considering its deflections is presented in this paper. With this method, tools with complex shapes and runout can be simulated in an efficient and flexible way. The new modeling approach is applied to exemplary milling processes and the simulation results are validated based on machining experiments.

In principle, most X-ray sensitive pixelated detectors like CCDs or active pixel sensors (e.g. CMOS detectors) can be operated in single-photon counting (SPC) mode. In combination with rather simple data post-processing steps, this allows the exploitation of energy-dispersive properties similar to hybrid-pixel detectors and pnCCDs. For example, energy discrimination can be used to simultaneously measure the spatial distribution of various fluorescence lines on the detector chip or enable noise suppression in wavelength-dispersive measurements. Furthermore, due to the analysis of the charge distribution on the detector resulting from an absorbed X-ray photon, sub-pixel spatial resolution can be achieved. Where applicable, those additional features can be utilized without any hardware modification at the detector. There is a large potential for novel experiments and sensitivity gain in many laboratories already applying pixelated detectors, but only a few experiments indeed use this potential. The up until now published algorithms are hardly validated and rarely described in detail. Besides a thorough description of various algorithms for photon event evaluation, this work concentrates on a quantitative and qualitative comparison of such algorithms with respect to energy resolution, efficiency and photon recovery. For this purpose, the algorithms are tested on simulated data featuring various detector noise and charge-cloud size values and the influence of noise thresholds and photon density is discussed. Finally, we present two examples to demonstrate the advantages of photon event evaluation and highlight its benefits for X-ray spectroscopic applications.

An angle resolved X-ray fluorescence spectrometer based on the concept of scanning-free shallow detection with energy-dispersive area detectors is presented. The instrument is characterized with respect to energy resolution, linearity, angular discrimination and repeatability and the necessary data evaluation strategies are presented in detail. As demonstration of its capabilities and showcase for potential applications, two different copper indium gallium (di)selenide (CIGS) absorber layers, typically applied in thin film solar cells, are analyzed. In combination with quantitative (but integral) results for layer composition and layer thickness from a commercial XRF spectrometer, depth profiles of the Ga concentration of both ≈ 2 μm thin samples are obtained. The results of the novel spectrometer compare well with quantitative depth-profiles obtained from glow-discharge optical emission spectrometry. The combination of simplicity, stability and efficiency of the spectrometer concept makes it a potential candidate for industrial applications. Description of compact angle-resolved X-ray fluorescence spectrometer. Exploiting scanning-free grazing emission X-ray fluorescence approach. Energy dispersive charge-coupled device with single-photon detection. Enabling non-destructive, quantitative elemental depth profiling. Depth profiling of nano-structured stratified specimen, here CIGS solar cells.

Dynamic models of machine tools can be used to predict their dynamic behavior in machining simulations. In a geometric-physical simulation a dynamic model comprising damped harmonic oscillators can be used to represent the frequency response functions (FRF) of the machine. The axis positions of milling machines change during machining and, thus, the FRFs vary. Therefore, the FRFs have to be determined at different locations in the workspace. Due to practical reasons, the number of measurement positions is limited. A method for interpolating the modal parameter values of the dynamic model is applied and evaluated.

With the advent of commercially available CMOS technology suitable for direct detection of photons in the soft X-ray range, new possibilities are opening up for the improvement and optimization of experiments requiring energy discrimination capabilities in this energy range. SDDs are widely used as energy-dispersive detectors, but they cannot be used with pulsed sources due to the overwhelming temporal photon density. Wavelength-dispersive solutions offer unmatched energy resolution, but suffer from low detection efficiency and a limited energy bandwidth which can be monitored. The use of common CCDs as energy-dispersive detectors in this energy range is limited by their energy resolution and especially their readout speed, which can result in significant experimental dead time and limits the usable frequency of pulsed sources. Therewhile, CMOS detectors with high energy resolution and high frame rates are an efficient, versatile and cost-effective alternative as detectors for pulsed sources. In this work we present the characterization of a commercially available, backside-illuminated CMOS detector regarding its energy resolution and quantum efficiency at the BESSY II synchrotron radiation facility with a well-known soft X-ray radiation source. Furthermore it is used in a proof of principle XRF measurement with a laboratory-based laser-plasma source.

Efficient multilayer optics for radiation in the water window range are difficult to manufacture due to extremely small layer thicknesses and severe intermixing of elements between the layers. Therefore, adequate analytics and short feedback loops are of utmost importance for manufacturers to improve performance and efficiency. We show the possibility for non-destructive elemental depth profiling with commercial laboratory equipment using four real-life CrSc multilayer samples. Comparative measurements at the laboratory of PTB at the synchrotron radiation facility BESSY II confirm the results and prove the potential of laboratory equipment for the reliable analysis of stratified materials with sub-nanometer layer thicknesses.

Angle‐resolved X‐ray fluorescence spectroscopy gives access to elemental analysis of nanoscaled materials. The two main techniques of this method are grazing incidence X‐ray fluorescence (GIXRF) and grazing emission X‐ray fluorescence (GEXRF) spectroscopy. Principles of both techniques including main applications are discussed in this Review. The main focus lies on the description of GEXRF technique and its new analytical possibilities in the nano‐world.

This article analyses how management culture and organizational structure shape economic success in social ventures (SVs). It finds out that an entrepreneurial orientation, taking care of the inter...

We present grazing incidence X-ray fluorescence (GIXRF) experiments on 3D periodically textured interfaces of liquid phase crystallized silicon thin-film solar cells on glass. The influence of functional layers (SiOx or SiOx/SiCx) – placed between glass substrate and silicon during crystallization – on the final carbon and oxygen contaminations inside the silicon was analyzed. Baring of the buried structured silicon surface prior to GIXRF measurement was achieved by removal of the original nano-imprinted glass substrate by wet-chemical etching. A broad angle of incidence distribution was determined for the X-ray radiation impinging on this textured surface. Optical simulations were performed in order to estimate the incident radiation intensity on the structured surface profile considering total reflection and attenuation effects. The results indicate a much lower contamination level for SiOx compared to the SiOx/SiCx interlayers, and about 25% increased contamination when comparing structured with planar silicon layers, both correlating with the corresponding solar cell performances.

A flexible spectrograph for the investigation of soft X-ray spectra in the range between 1 nm and 20 nm is presented. Based on two variable-line spaced reflection gratings, the design enables stand-alone operation, the change between the use of an entrance slit and a slitless operation mode as well as a maximum compactness and robustness due to a reduced number of motorized stages. Characterization measurements as well as first proof-of-principle X-ray emission investigations show the potential of the instrument for versatile applications.A flexible spectrograph for the investigation of soft X-ray spectra in the range between 1 nm and 20 nm is presented. Based on two variable-line spaced reflection gratings, the design enables stand-alone operation, the change between the use of an entrance slit and a slitless operation mode as well as a maximum compactness and robustness due to a reduced number of motorized stages. Characterization measurements as well as first proof-of-principle X-ray emission investigations show the potential of the instrument for versatile applications.

Recent studies suggest that the ecotoxicity of engineered nanoparticles (ENPs) is dependent upon the treatment of ENPs in suspensions (e.g. sonication or use of solvents) and on the mode of exposure to test organisms. We conducted several bioassays with Daphnia magna in order to determine how adverse effects of TiO2 nanoparticles (n-TiO2) are influenced by experimental set-up. Several treatments were applied, including three test media, several treatments of n-TiO2 suspensions (stirring, sonication) and different exposure modes (exposure duration and volume of test suspension). No adverse effects were observed when D. magna were exposed to 50 mL of suspension, regardless of TiO2 concentration (up to 250 mg/L) and exposure duration. Conversely, adverse effects were observed when D. magna were exposed to 2 mL of suspension for 96 h with a 50 % effect concentration EC50 values ranging from 32 mg/L to 82 mg/L. Test media had no significant influence on the outcome of all treatments. For a better mechanistic understanding of the experimental set-up at which adverse effects were observed, the particle size of n-TiO2 in the test media was characterized throughout the test duration. These measurements revealed a fast and strong agglomeration with a secondary particle size in the order of magnitude of micrometers. Our study describes how the effects of n-TiO2 on D.magna are influenced by the duration of exposure and volume of media, highlighting the need for standardization of experimental methods. © 2015, Springer-Verlag Berlin Heidelberg.

International audience; Manufacturing of nanomaterials (NMs) is often complex and expensive, and their environmental risks are poorly understood or even unknown. An economization of testing NMs is therefore desirable, which can be achieved by miniaturizing test systems. However, the downsizing of test vessels and volumes can enlarge the surface/volume ratio (SVR) which in turn can affect the bioavailable concentration of adsorbing substances like NMs. The present study focused on the miniaturization of the acute toxicity test with Daphnia magna. The adaptations were verified with three reference substances, the non-adsorbing potassium dichromate (K2Cr2O7) and as potentially highly-adsorbing substances silver nanoparticles (AgNPs) and silver nitrate (AgNO3). The miniaturized test was conducted in 24-well microtiter plates (MT) and simultaneously compared to the OECD standard test (ST). Furthermore, the test duration was prolonged from 48 to 96 h since NMs tend to show effects only after extended exposure. The toxicity of K2Cr2O7 and AgNPs continued to increase within the prolonged test span. The test comparisons with K2Cr2O7 did not reveal any significant differences between ST and MT. AgNO3 toxicity was significantly decreased in MT compared to ST due to the enlarged SVR. The toxicity of AgNPs in MT after 24 h was equal to ST. Contrary to our expectations an exposure longer than 24 h resulted in an increase of AgNP toxicity in MT, possibly due to enhanced dissolution of silver. Microtiter plates are appropriate alternative test vessels for the Daphnia sp. acute toxicity test; thus, its miniaturization is feasible. The enlarged SVR has to be taken into account since it can affect the toxicity of potentially adsorbing substances. Furthermore, the standard test duration of 48 h might underestimate the toxicity of many substances, especially of NMs.

The surface of nanoparticles (NP) is often functionalized with a capping agent to increase their colloidal stability. Having a strong effect on the characteristics of NP, the coating might already determine the risk from NP to organisms and the environment. In this study identical iron oxide nanoparticles (IONP; O 5-6nm) were functionalized with four different coatings: ascorbate (ASC-IONP), citrate (CIT-IONP), dextran (DEX-IONP), and polyvinylpyrrolidone (PVP-IONP). Ascorbate and citrate stabilize NP via electrostatic repulsion whereas dextran and polyvinylpyrrolidone are steric stabilizers. All IONP were colloidally stable over several weeks. Their acute effects on neonates of the waterflea Daphnia magna were investigated over 96h. The highest immobilizing effect was found for ASC- and DEX-IONP. In the presence of neonates, both agglomerated or flocculated and adsorbed to the carapace and filtering apparatuses, inducing high immobilization. Lower immobilization was found for CIT-IONP. Their effect was hypothesized to partly originate from an increased release of dissolved iron and the ability to form reactive oxygen species (ROS). Furthermore, incomplete ecdysis occurred at high concentrations of ASC-, DEX-, and CIT-IONP. PVP-IONP did not induce any negative effect, although high quantities were visibly ingested by the daphnids. PVP-IONP had the highest colloidal stability without any occurring agglomeration, adsorption, or dissolution. Only strong swelling of the PVP coating was observed in medium, highly increasing the hydrodynamic diameter. Each coating caused individual effects. Toxicity cannot be correlated to hydrodynamic diameter or the kind of stabilizing forces. Effects are rather linked to decreasing colloidal stability, the release of ions from the core material or the ability to form ROS, respectively.

In the water window (2.2 – 4.4 nm) the attenuation of radiation in water is significantly smaller than in organic material. Therefore, intact biological specimen (e.g. cells) can be investigated in their natural environment. In order to make this technique accessible to users in a laboratory environment a Full-Field Laboratory Transmission X-ray Microscope (L-TXM) has been developed. The L-TXM is operated with a nitrogen laser plasma source employing an InnoSlab high power laser system for plasma generation. For microscopy the Lyα emission of highly ionized nitrogen at 2.48 nm is used. A laser plasma brightness of 5 × 1011 photons/(s × sr × μm2 in line at 2.48 nm) at a laser power of 70 W is demonstrated. In combination with a state-of-the-art Cr/V multilayer condenser mirror the sample is illuminated with 106 photons/(μm2 × s). Using objective zone plates 35 – 40 nm lines can be resolved with exposure times < 60 s. The exposure time can be further reduced to 20 s by the use of new multilayer condenser optics and operating the laser at its full power of 130 W. These exposure times enable cryo tomography in a laboratory environment.

Iron oxide nanoparticles (IONP) are currently being studied as green magnet resonance imaging (MRI) contrast agents. They are also used in huge quantities for environmental remediation and water treatment purposes, although very little is known on the consequences of such applications for organisms and ecosystems. In order to address these questions, we synthesised polyvinylpyrrolidone-coated IONP, characterised the particle dispersion in various media and investigated the consequences of an IONP exposure using an array of biochemical and biological assays. Several theoretical approaches complemented the measurements. In aqueous dispersion IONP had an average hydrodynamic diameter of 25 nm and were stable over six days in most test media, which could also be predicted by stability modelling. The particles were tested in concentrations of up to 100 mg Fe per L. The activity of the enzymes glutathione reductase and acetylcholine esterase was not affected, nor were proliferation, morphology or vitality of mammalian OLN-93 cells although exposure of the cells to 100 mg Fe per L increased the cellular iron content substantially. Only at this concentration, acute toxicity tests with the freshwater flea Daphnia magna revealed slightly, yet insignificantly increased mortality. Two fundamentally different bacterial assays, anaerobic activated sludge bacteria inhibition and a modified sediment contact test with Arthrobacter globiformis, both rendered results contrary to the other assays: at the lowest test concentration (1 mg Fe per L), IONP caused a pronounced inhibition whereas higher concentrations were not effective or even stimulating. Preliminary and prospective risk assessment was exemplified by comparing the application of IONP with gadolinium-based nanoparticles as MRI contrast agents. Predicted environmental concentrations were modelled in two different scenarios, showing that IONP could reduce the environmental exposure of toxic Gd-based particles by more than 50%. Application of the Swiss “Precautionary Matrix for Synthetic Nanomaterials” rendered a low precautionary need for using our IONP as MRI agents and a higher one when using them for remediation or water treatment. Since IONP and (considerably more reactive) zerovalent iron nanoparticles are being used in huge quantities for environmental remediation purposes, it has to be ascertained that these particles pose no risk to either human health or to the environment.

X-ray microscopy in the water window has become a valuable imaging tool for a wide field of applications with a resolution in the nanometer regime. The emergence and the development of laboratory based transmission X-ray microscopes (LTXM) can be of great benefit to users, since LTXM provides access to a method previously limited to synchrotron facilities only. In recent years, measuring times in the laboratory have been reduced to the point, where tomography of aqueous cryofixated samples has become feasible. We report on a laboratory full-field transmission X-ray microscope based on a laser induced plasma source located at the Berlin Laboratory for innovative X-ray Technologies. A short introduction on full-field X-ray microscopy in the water window is given. We demonstrate that, with a thin disk laser-system (TDL), which provides an average power of ~15 W a spatial resolution of Δx = 41 nm ± 3 nm (half-pitch) is feasible. An image of a diatom recorded at 15 W average laser power with a magnification of 1125x captured in 5 min is presented.

The genetic diversity of natural populations and the increase in global temperature are be- coming important issues in ecotoxicological research. We investigated the combined effects of 3 differ- ent temperature levels and 6 different levels of genetic diversity on the life history parameters of Chi- ronomus riparius. Inbreeding and loss of genetic variation are major threats to small and endangered populations. The reduction of fitness due to inbreeding is more severe under stressful environmental conditions. We show that under even a moderate temperature stress, a decrease in genetic variation has important consequences on the fitness of populations. This indicates that the global temperature increase could have serious effects on the distribution and survival of locally distributed or rare species.