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Low temperature performance is key for catalysts used in selective catalytic reduction of NOx with ammonia (NH3-SCR). The best performing NH3-SCR catalysts are based on small pore copper loaded zeolites. A key question remains which structural and compositional parameters make a copper zeolite catalytically active in this application. In this work a collection of 83 different zeolite samples having 25 different frameworks and compositional variations was evaluated to uncover the critical structural and compositional parameters governing catalytic activity at 150 °C. The Si/Al ratio, the content of double six ring building units, the framework density and pore dimensionality were identified as having a strong impact on the catalytic activity of zeolites. A critical value for each of these parameters was determined. This knowledge was used to predict MOZ, SZR and GME as active NH3-SCR catalysts. They were synthesized respecting the compositional prerequisites and their catalytic evaluation confirmed the predicted high catalytic activity. ispartof: Journal Of Catalysis vol:390 pages:224-236 status: published

We report carbonization of polyacrylonitrile by direct laser writing to produce microsupercapacitors directly on-chip. We demonstrate the process by producing interdigitated carbon finger electrodes directly on a printed circuit board, which we then employ to characterize our supercapacitor electrodes. By varying the laser power, we are able to tune the process from carbonization to material ablation. This allows to not only convert pristine polyacrylonitrile films into carbon electrodes, but also to pattern and cut away non-carbonized material to produce completely freestanding carbon electrodes. While the carbon electrodes adhere well to the printed circuit board, non-carbonized polyacrylonitrile is peeled off the substrate. We achieve specific capacities as high as 260 µF/cm2 in a supercapacitor with 16 fingers.

Carbon nanofiber nonwovens are promising materials for electrode or filtration applications; however, their utilization is obviated by a lack of high throughput production methods. In this study, we utilize a highly effective high-throughput method for the fabrication of polyacrylonitrile (PAN) nanofibers as a nonwoven on a dedicated substrate. The method employs rotational-, air pressure- and electrostatic forces to produce fibers from the inner edge of a rotating bell towards a flat collector. We investigate the impact of all above-mentioned forces on the fiber diameter, morphology, and bundling of the carbon-precursor PAN fibers. The interplay of radial forces with collector-facing forces has an influence on the uniformity of fiber deposition. Finally, the obtained PAN nanofibers are converted to carbon nonwovens by thermal treatment., publishedVersion

This paper attempts to elucidate fundamental mechanisms of the brittle-to-ductile transition (BDT) in textured, pre-deformed, polycrystalline body-centred cubic metals. For this purpose, five tungsten sheets have been rolled out from one and the same sintered ingot representing degrees of deformation of 1.8, 2.5, 3.0, 3.4, and 4.1 (logarithmic notation). Electron backscatter diffraction measurements display the evolution of the microstructure with increasing degree of deformation. The mean grain size of the five sheets in the normal direction is 1.1, 0.59, 0.48, 0.37, and 0.3 μm. Toughness tests based on the K-concept have been performed and the brittle-to-ductile transition temperature of the five sheets has been determined. The crack system used was the L-T crack system. The results have been benchmarked against the BDT temperature of a sintered ingot. The results show a decrease of the BDT temperature with increasing degree of deformation starting from 600 °C (873 K) for the sintered ingot via 115 °C (388 K), 85 °C (358 K), 75 °C (348 K), 60 °C (333K) down to − 65 °C (208 K) for the most heavily deformed tungsten plate. The results are discussed against the background of (i) rolling induced lattice defects such as (i-a) vacancies, (i-b) dislocations (i-c) grain boundaries, (ii) crystallographic texture, (iii) the state of stress, (iv) impurities, (v) sinter pores, and (vi) the geometrical arrangement of areas with low and high fracture toughness. The authors postulate that the BDT is still controlled by the kink-pair nucleation process of a screw dislocation and that the BDT temperature scales with the spacing of dislocation sources (e.g. grain boundary ledges, low angle boundaries, debris loops) along the crack front.

This paper is the second part of our series on ultrafine-grained (UFG) tungsten produced by cold rolling. The aim of this paper is to determine tensile properties, with a focus on uniform elongation and flow stress, and to identify the mechanism of plastic deformation in cold rolled tungsten plates and foils. For this purpose, five plates have been rolled out of a single sintered compact with increasing degrees of deformation, which enables the analysis of mechanical properties with changing microstructure without influence from the chemical composition. Uniaxial tensile tests have been performed in the range of room temperature to 800 °C. The tensile curves show a clear trend of increased strength for finer microstructures and simultaneously evolving room temperature ductility in the low temperature regime for cold rolled plates. The thinnest foil (100 μm) behaves uniquely by forming a plateau in the stress-strain curve, which hints at a change in the deformation mechanism. Analyzing the temperature and grain size dependence of the flow stress reveals that the bulk plasticity is still controlled by screw dislocations and further suggests a change in the dislocation-grain boundary interactions from blocking at low homologous temperatures to absorbing at elevated temperatures. A fracture analysis of cold rolled tungsten foils confirms a plastic deformation prior to fracture and reveals a steady transition from brittle towards lamellar fracture for the highly deformed tungsten foils.

Zeolites are microporous materials driving industrial scale adsorption, ion exchange, and catalytic processes. Their water content dramatically impacts their properties, but its quantification with Karl Fisher titration or thermal gravimetric analysis is problematic. When standard addition of water is combined with 1H magic angle spinning (MAS) NMR detection, absolute quantification of water in microporous materials becomes possible. The method was demonstrated on five different, commercially available zeolites.

Epimerization of sugars is a carbon-efficient route not only to produce rare carbohydrates but also to extend the product scope for chemical production in future biorefineries. Industrially available catalysts for epimerization are limited mainly to soluble Mo(VI) species as well as substrate-specific epimerases. Here we report highly active and selective tin-organic frameworks (Sn-OF) as solid catalysts for the epimerization of aldoses at the C-2 position, such as the conversion of glucose to mannose. The reaction proceeds via a carbon skeleton rearrangement, that is, through breaking of a C-2/C-3 carbon bond and formation of a C-1/C-3 bond. Partially hydrolyzed Ph3Sn-OH sites were found to be the catalytically active centers. Our results suggest that the high catalytic activity of Sn-OFs for the epimerization is determined by (1) Lewis acidity of tin; (2) free Sn-OH groups; and (3) the high hydrophobicity of organic linkers applied in the aqueous solutions.

Conventionally produced tungsten (W) sheets are brittle at room temperature. In contrast to that, severe deformation by cold rolling transforms W into a material exhibiting room-temperature ductility with a brittle-to-ductile transition (BDT) temperature far below room temperature. For such ultrafine-grained (UFG) and dislocation-rich materials, the mechanism controlling the BDT is still the subject of ongoing debates. In order to identify the mechanism controlling the BDT in room-temperature ductile W sheets with UFG microstructure, we conducted campaigns of fracture toughness tests accompanied by a thermodynamic analysis deducing Arrhenius BDT activation energies. Here, we show that plastic deformation induced by rolling reduces the BDT temperature and also the BDT activation energy. A comparison of BDT activation energies with the trend of Gibbs energy of kink-pair formation revealed a strong correlation between both quantities. This demonstrates that out of the three basic processes, nucleation, glide, and annihilation, crack tip plasticity in UFG W is still controlled by the glide of dislocations. The glide is dictated by the mobility of the screw segments and therefore by the underlying process of kink-pair formation. Reflecting this result, a change of the rate-limiting mechanism for plasticity of UFG W seems unlikely, even at deformation temperatures well below room temperature. As a result, kink-pair formation controls the BDT in W over a wide range of microstructural length scales, from single crystals and coarse-grained specimens down to UFG microstructures.

Beside its armor function, the designated divertor plasma-facing material tungsten (W) is also foreseen to fulfill a structural function. For fail-safe operation, strategies to overcome the brittle nature at room temperature of W are highly demanded. Since in an environment with high neutron fluences W-alloys with sufficient Rhenium concentrations have to be ruled out, the generation of tailored microstructures has come in focus. In order to assess deformation-induced modifications in the microstructure, we conducted electron backscatter diffraction (EBSD) and electron channeling contrast imaging experiments (ECCI) on warm- and cold rolled W sheets combined with studies on the related shift in brittle-to-ductile transition (BDT) temperature. With this work, we demonstrate the existence of empirical relationships between the evolution in transition temperature and the changing density of boundaries with increasing strain conducted by rolling, whereby best correlations were derived considering both, low-angle and high-angle boundaries. A Hall–Petch-like relationship based on the mean boundary spacing along the crack front and a modified version also reflecting the high aspect ratios of the grains are well-suited to describe the evolution in transition temperature and its anisotropic nature. Our findings support the theory suggesting the assisted dislocation nucleation at boundaries as decisive factor for more effective shielding of the crack tip in UFG materials leading to reduced BDT temperature. In addition, this work gives strong indications that the rolling-induced reduction of the BDT temperature in W is not related to coincidence site lattice (CSL) boundaries.

This paper is the first part of our series on ultrafine-grained (UFG) tungsten produced by cold rolling. The aim of our project is to investigate the correlation between microstructure, mechanical properties and deformation mechanisms in UFG tungsten, a material interesting for future high-temperature applications. For this purpose, a batch of tungsten sheets with different thicknesses has been produced by subsequent cold rolling out of a single sintered compact. The aim of this paper is to characterise the microstructure of the as-received tungsten sheets. Quantitative grain size analysis by EBSD confirms a grain refinement by cold rolling well down into the UFG-regime, reaching 240 nm in the S-direction for the 100 μm foil. The grain refinement comes with an increase in the number of HAGBs, while LAGBs show no correlation with the degree of deformation introduced by cold rolling. All plates are distinctively textured, the main texture being the {001}〈110〉-orientation (rotated cube texture). Vickers microhardness measurements confirm a steady increase in hardness with advanced rolling up to 687 kg/mm 2 for the 100 μm foil. This indicates that the one-dimensional grain refinement to UFG by cold rolling is sufficient to achieve properties comparable to other UFG tungsten specimens. Therefore, it can be concluded that the batch of samples introduced in this paper will be fit to investigate the evolution of mechanical properties and deformation mechanisms in correlation with the microstructure.

Severely deformed cold-rolled tungsten is a promising structural material for future fusion reactor applications due to high melting temperature and excellent mechanical properties. However, the fine-grained microstructure after deformation is not stable at temperatures above 800 °C, leading to brittle material behaviour. In this study, we utilize potassium-doping to inhibit recrystallization of tungsten sheets, a mechanism well known from incandescent lamp wires. We produced K-doped tungsten sheets by warm-rolling and subsequent cold-rolling with five different logarithmic strains up to 4.6, and equivalently rolled pure tungsten sheets. Both sets of materials are compared using EBSD and microhardness testing. In both materials, the hardness increases and the grain size along normal direction decreases with strain; the densities of low and high angle boundaries increase in particular during cold-rolling. The K-doped W sheet reaches the highest hardness with 772 ± 8 HV0.1, compared to the pure W sheet with 711 ± 14 HV0.1. All boundaries taken into account, a Hall-Petch relation describes the hardness evolution nicely, except a deviation of the K-doped tungsten sheet rolled to highest strain with its much higher hardness. The similar structural and mechanical properties of both materials in the as-rolled condition allow further studies of recrystallization behaviour of the new K-doped material with a benchmark against the equivalent pure tungsten sheets. Isochronal annealing for 1 h was performed at different temperatures between 700 °C and 2200 °C. A sharp decrease in hardness to intermediate values is observed at around 900 °C for both materials, presumably reflecting extended recovery. A second decrease is observed at 1400 °C for pure tungsten, approaching the hardness of a single crystal and indicating recrystallization and severe growth of grains. For K-doped tungsten, however, the occurrence of the second decrease is shifted to higher temperatures from 1400 °C to 1800 °C with increasing strain and an intermediate hardness is maintained up to 1800 °C. We refer this dependence of the recrystallization resistance on strain in the K-doped material to the dispersion of K-bubbles, resulting in increased Zener pinning forces retarding boundary motion.

This paper describes a systematic analysis of liquid-phase infiltrated molybdenum (Mo) copper (Cu) composites, deformed by various levels, and elucidates the impact of (i) the copper content, and (ii) the rolling reduction on the evolution of the material properties. The rolling-induced change of the thermo-physical properties can be traced back to (ii-a) the evolution of the geometry (viz. the flattening of the molybdenum and the copper phase during rolling) and (ii-b) the evolution of the crystallographic texture. Four infiltrated ingots with a copper content of 23, 39, 48 and 54 vol % were produced. Each ingot was gradually rolled down to a final degree of deformation of 0.5, 1, 1.5, 2 and 2.38, which corresponds to a rolling reduction of 39%, 63%, 78%, 86% and 90%. In summary, four material compositions (23, 39, 48 and 54 vol % Cu) in six conditions (as-infiltrated and five as-rolled conditions) were examined. The evolution of the microstructure is correlated with the evolution of the mechanical and thermo-physical properties such as hardness (HV2), Young's modulus, E , electrical conductivity, σ , thermal conductivity, k , and the coefficient of thermal expansion, α (CTE, in the range of 350 °C (623 K) – 750 °C (1023 K)). It was found, that the same thermal conductivity can be gained by using either a low copper-content composite that features a low degree of deformation or by using a high copper-content composite that was rolled down to a high degree of deformation. Furthermore, we were able to demonstrate that peculiarities in the CTE-over-T curves can be traced back to the plastic deformation of the copper phase, which is affected by rolling-induced residual stresses and recrystallisation processes during the CTE measurement.

EU-7 zeolite with Si/Al ratio of 15 is identified as a BIK type zeolite. The framework charge is compensated with Cs+ cations located in 8-ring channels at regular distances. Even partially exchanged, Cu-loaded EU-7 is active in NH3-SCR and withstands hydrothermal aging at 900 °C needed for application in diesel particulate filters. ispartof: Chemical Communications (London) vol:54 issue:44 pages:5626-5629 ispartof: location:England status: published

Through the synthesis of a tungsten laminate made of ultrafine-grained (UFG) tungsten foils, a UFG bulk material can be made that retains the ductility and toughness of the tungsten foils. Considering tungsten laminates as a structural material the ageing behaviour is of utmost importance. In this paper we analyse and discuss the ageing behaviour of tungsten laminates produced by diffusion bonding using a titanium (Ti) interlayer. The evolution of the mechanical properties (Charpy impact, hardness) and the evolution of the microstructure during annealing at 1000 °C for 10 h, 100 h, and 1000 h in vacuum are studied. The calculated Ti–W phase diagram, as well as the calculated interdiffusion coefficients and interdiffusion profiles, significantly relate to the understanding of the evolution of the W–Ti interface. Comparison of Auger electron spectroscopy (AES) and scanning electron microscope (SEM) analyses with the simulated diffusion data provides an in-depth understanding of the diffusion mechanisms and the evolution of the microstructure. The elucidation of the diffusion mechanisms of W–Ti laminates will advance several research fields such as the production of UFG bulk material and the synthesis of advanced fracture toughness test samples.

Here we show that potassium-doped tungsten foil should be preferred to pure tungsten foil when considering tungsten laminate pipes for structural divertor applications. Potassium-doped tungsten materials are well known from the bulb industry and show an enhanced creep and recrystallization behaviour that can be explained by the formation of potassium-filled bubbles that are surrounding the elongated grains, leading to an interlocking of the microstructure. In this way, the ultra-fine grained (UFG) microstructure of tungsten foil can be stabilized and with it the extraordinary mechanical properties of the foil in terms of ductility, toughness, brittle-to-ductile transition, and radiation resistance. In this paper we show the results of three-point bending tests performed at room temperature on annealed pure tungsten and potassium-doped tungsten foils (800, 900, 1000, 1100, 1200, 1300, 1400, 1600, 1800, 2000, 2200, and 2400 °C for 1 h in vacuum). The microstructural assessment covers the measurement of the hardness and analyses of fractured surfaces as well as a comparison of the microstructure by optical microscopy. The results show that there is a positive effect of potassium-doped tungsten foils compared to pure tungsten foil and demonstrate the potential of the doped foil.

In this study, we present the recrystallisation behaviour of heavily cold rolled tungsten sheets and show that the material recrystallises towards a single texture component, i.e. the rotated cube component {001} . This result is remarkable as it distinguishes from the classical concept of recrystallisation and is likely to have a strong impact in various fields in science and technology. The thermal stability of as-rolled tungsten sheets featuring a thickness reduction of 98% (i.e. 4.1 in the logarithmic notation) was investigated. Annealings were performed in a vacuum and in the temperature range of 400 °C (673 K) to 2000 °C (2273 K) for a time period of 6 min up to 500 h. The annealing-induced evolution of the microstructure is displayed by hardness (HV0.1) and electron backscatter diffraction (EBSD) measurements. The results show that after an annealing of 6 min at 800 °C (1073 K), the hardness drops from 666 ± 6.3 to 625 ± 7.9 HV0.1. The evolution of the hardness is fitted by classical kinetic models for recovery (logarithmic kinetics) and recrystallisation. The apparent activation energy of half of the hardness loss, EΔHV/2, was found to be 356 kJ/mol (3.69 eV), which can be associated with the activation energy of grain boundary diffusion in tungsten. Furthermore, the hardness data allows for the distinction between two stages. In stage I, the material rapidly develops an equiaxed grain structure by the break-up and spheroidisation of the high aspect ratio grains. We do not observe the formation of nuclei in the classical sense. Moreover, the recrystallisation processes can be described as grain growth. We suggest the dominant driving force to be the reduction of the internal stored energy. Finally, the transition from stage I to stage II is caused by the onset of abnormal grain growth.

Polyurethanes are the only class of polymers that display thermoplastic, elastomeric, and thermoset behavior depending on their chemical and morphological makeup. In addition to compact polyurethanes, foamed variations in particular are very widespread, and they achieve their targeted properties at very low weights. The simple production of sandwich structures and material composites in a single processing step is a key advantage of polyurethane technology. The requirement of energy and resource efficiency increasingly demands lightweight structures. Polyurethanes can serve this requirement by acting as matrix materials or as flexible adhesives for composites. Polyurethanes are indispensable when it comes to high-quality decorative coatings or maintaining the value of numerous objects. They are extremely adaptable and sustainable problem solvers for today's challenges facing our society, all of which impose special demands on materials.

This paper is the fourth in our series on tungsten laminates. The aim of this paper is to discuss laminate synthesis, meaning the joining of tungsten foils. It is obvious that the properties of the tungsten laminate strongly depend on the combination of (i) interlayer and (ii) joining technology, as this combination defines (i) the condition of the tungsten foil after joining (as-received or recrystallised) as well as (ii) the characteristics of the interface between the tungsten foil and the interlayer (wettability or diffusion leading to a solid solution or the formation of intermetallics). From the example of tungsten laminates joined by brazing with (i) an eutectic silver copper brazing filler, (ii) copper, (iii) titanium, and (iv) zirconium, the microstructure will be discussed, with special focus on the interface. Based on our assumptions of the mechanism of the extraordinary ductility of tungsten foil we present three syntheses strategies and make recommendations for the synthesis of high temperature tungsten laminates.

Recrystallized and deformed tungsten were investigated regarding their crack resistance as a function of crack extension. The compact tension specimens were manufactured with different crack plane orientations with respect to the axis of a rod. All recrystallized samples fractured predominantly intergranularly, whereas the deformed samples fractured transgranularly in certain crack propagation directions. Both showed an increase in the fracture resistance with crack extension, i.e. they exhibit R -curve behavior. It was determined in this study that the consolidation of the various fracture planes and crack bridging cause this R -curve behavior in tungsten.

This paper is the third part of our series on tungsten foil laminates. Within the tungsten laminate project we have succeeded in ductilizing tungsten by synthesizing a tungsten laminate made of tungsten foil, which is ductile. By assembling and joining several layers of tungsten foil, the ductile properties of the foil can be extended to the bulk. The aim of this paper is to present the results of tensile tests on 100-μm-thick tungsten foil in as-received and recrystallized conditions (1 h at 2000 °C). The results show that the mechanical properties of tungsten foil are anisotropic and can be explained by considering (i) the texture of the tungsten foil of {1 0 0}〈0 1 1〉, (ii) the anisotropic grain shape (0.5 μm × 3 μm × 15 μm), (iii) the preferred slip direction of body-centered cubic (bcc) metals, the 〈1 1 1〉 direction, as well as the preferred cleavage plane of tungsten at room temperature, the {1 0 0} plane. Furthermore, the results give further hints for the sources and mechanism of the extraordinary ductility of tungsten foil such as the ‘foil effect’, which is the dislocation annihilation at the free surface. In particular, the ductile material behavior of tungsten foil in the recrystallized condition seems to benefit from the foil effect and this is how a plastic strain of about 30% in a tensile test at 600 °C can be explained.

It has been attempted for several years to synthesize a tungsten material with a low brittle-to-ductile transition temperature and a high fracture toughness that can be used for structural parts. In this work, we show how to realize the ductilization of tungsten: by synthesizing a laminate made of tungsten foil. This paper shows that tungsten foil is ductile in a tensile test performed at room temperature. The idea now is to expand the ductile material properties of the tungsten foil to a bulk, by assembling several layers of this ductile tungsten foil. By doing this, a tungsten laminate can be synthesized. This laminate is characterized by a Charpy impact test and the results are compared to tungsten plate material. The results of the tungsten laminate are excellent: nearly 2 J of energy absorption at room temperature, 5 J at 100 °C and 10 J at 300 °C (measured by KLST standard). Even more overwhelming are the results obtained from a tungsten laminate synthesized with recrystallized tungsten foil (annealed for 1 h/1800 °C). Here, the brittle ductile transition is at 500 °C, which is an improvement of at least 500 °C compared to recrystallized plate material (1 h/2000 °C). As a last step we present the first ductile tungsten pipe that can be used for structural applications: a tungsten pipe made of tungsten foil.

The influence of both microstructure and chemical composition on the fracture behaviour of tungsten–tantalum, tungsten–vanadium composites and alloys of varying chemical compositions are investigated. Industrial solid solution tungsten–tantalum alloys with different tantalum contents in the as-forged condition are investigated along with different tungsten–tantalum and tungsten–vanadium composites and alloys made by powder consolidation, severe plastic deformation using high pressure torsion and different subsequent heat treatments. To investigate the fracture behaviour, several crack propagation directions in relation to the forging direction and shear direction, respectively, are taken into account. Heat treatment of the composite material results in a more homogeneous distribution of the alloying element and the impacts of these specific heat treatments on microstructure and fracture toughness are discussed. The fracture experiments are performed within a temperature range from room temperature to 600 °C and reveal a strong dependence of the fracture toughness and fracture morphology on temperature and on the microstructure, and hence the processing history of the materials.

The directionality of interaction of electron-deficient π systems with spherical anions (e.g,. halides) can be controlled by secondary effects like NH or CH hydrogen bonding. In this study a series of pentafluorophenyl-substituted salts with polyhalide anions is investigated. The compounds are obtained by aerobic oxidation of the corresponding halide upon crystallization. Solid-state structures reveal that in bromide 2, directing NH-anion interactions position the bromide ion in an η(1)-type fashion over but not in the center of the aromatic ring. The same directing forces are effective in corresponding tribromide salt 3. In the crystal, the bromide ion is paneled by four electron-deficient aromatic ring systems. In addition, compounds 4 and 6, which have triiodide and the rare tetraiodide dianion as anions, are described. Computational studies reveal that the latter is highly unstable. In the present case it is stabilized by the crystal lattice, for example, by interaction with electron-deficient π systems.

The possible use of tungsten alloys as structural materials in future fusion reactor divertors strongly depend on their ductile-to-brittle transition temperature (DBTT). The present paper gives an overview on different rod and plate materials fabricated by PLANSEE. It is demonstrated that DBTT is clearly improved compared to commercially available standard materials. Moreover, the significant impact of the microstructure on fracture mode and on toughness is discussed in detail.

Of all human endogenous retroviruses known today, HERV-K is the only one that has been shown to produce viral particles. While the first of the approximately 30 HERV-K sequences integrated into the human genome more than 40 million years ago, evidence is accumulating that HERV-K was active more recently, provirus HERV-K113 being the youngest sequence found. However, it is unclear which HERV-K sequences code for the viral particles that are produced by human germ-cell tumours or melanomas. Here, we show that the provirus HERV-K113, cloned into a baculovirus expression vector, is capable of producing intact particles of retroviral morphology, exhibiting the typical structure of those particles that were characterized in cell lines derived from human germ-cell tumours. Thus, the HERV-K113 sequence is a candidate for particle production in vivo and for an active human endogenous retrovirus of today.

Chemical sensing on oxide sensors is a complex phenomenon involving catalytic activity as well as electronic properties. Thus, the properties of oxide sensors are highly sensitive towards structural changes. Effects like surface area, grain size, and, in addition, the occurrence of defects give separate contributions to the current. Structure property function relationships can be elucidated using a combination of state-of-the-art analytical techniques. It is shown, that impurity atoms in the oxide lattice influence the performance of ZnO sensors more strongly than the other factors.

The molybdenum alloy TZM (Mo-0.5wt%Ti-0.08wt%Zr) is a commonly used structural material for high temperature applications. For these purposes a high strength at elevated temperatures and also a sufficient ductility at room temperature are being aimed. Preceding investigations revealed the existence of subgrains in hot deformed TZM. It was observed that with proceeding primary recrystallization and therefore with disappearance of subgrains the yield strength drops almost to a level of pure molybdenum. It is being assumed that the existence of a dislocation substructure has a pronounced effect on the yield strength of TZM. The aim of the present study was to evaluate the subgrain and texture formation and also to estimate the dislocation arrangement within subgrains during hot deformation. Hence, TZM rods were rolled to different degrees of deformation at a temperature above 0.5 Tm. The microstructure of the initial material was fully recrystallized. Texture formation, misorientation distributions and subgrain sizes were analyzed by electron backscattering diffraction (EBSD). Mechanical properties were characterized by tensile tests at room temperature and up to 1200°C. It was revealed, that with increasing degree of deformation a distinct substructure forms and therefore yield strength rises. Consequently, the misorientation between adjacent subgrains increases, their size decreases and a fibre texture develops. To estimate the influence of texture on strength of TZM the Taylor factors are calculated from EBSD data.

An extension of multi-volatile method (MVM) technology using the combination of a standard dynamic headspace (DHS) configuration, and a modified DHS configuration incorporating an additional vacuum module, was developed for milliliter injection volume of aqueous sample with full sample evaporation. A prior step involved investigation of water management by weighing of the water residue in the adsorbent trap. The extended MVM for 1 mL aqueous sample consists of five different DHS method parameter sets including choice of the replaceable adsorbent trap. An initial two DHS sampling sets at 25°C with the standard DHS configuration using a carbon-based adsorbent trap target very volatile solutes with high vapor pressure (10 kPa) and volatile solutes with moderate vapor pressure (1-10 kPa). Subsequent three DHS sampling sets at 80°C with the modified DHS configuration using a Tenax TA trap target solutes with low vapor pressure (1 kPa) and/or hydrophilic characteristics. After the five sequential DHS samplings using the same HS vial, the five traps are sequentially desorbed with thermal desorption in reverse order of the DHS sampling and the desorbed compounds are trapped and concentrated in a programmed temperature vaporizing (PTV) inlet and subsequently analyzed in a single GC-MS run. Recoveries of 21 test aroma compounds in 1 mL water for each separate DHS sampling and the combined MVM procedure were evaluated as a function of vapor pressure in the range of 0.000088-120 kPa. The MVM procedure provided high recoveries (88%) for 17 test aroma compounds and moderate recoveries (44-71%) for 4 test compounds. The method showed good linearity (r(2)0.9913) and high sensitivity (limit of detection: 0.1-0.5 ng mL(-1)) even with MS scan mode. The improved sensitivity of the method was demonstrated with analysis of a wide variety of aroma compounds in brewed green tea. Compared to the original 100 μL MVM procedure, this extension to 1 mL MVM allowed detection of nearly twice the number of aroma compounds, including 18 potent aroma compounds from top-note to base-note (e.g. 2,3-butanedione, coumarin, furaneol, guaiacol, cis-3-hexenol, linalool, maltol, methional, 3-methyl butanal, 2,3,5-trimethyl pyrazine, and vanillin). Sensitivity for 23 compounds improved by a factor of 3.4-15 under 1 mL MVM conditions.

The technology of 3D printing is conquering the world and awakens the interest of many users in the most varying of applications. New formulation approaches for photo-sensitive thiol-ene resins in combination with various printing technologies, like stereolithography (SLA), projection based printing/digital light processing (DLP) or two-photon polymerization (TPP) are presented. Thiol-ene polymerizations are known for its fast and quantitative reaction and to form highly homogeneous polymer networks. As the resins are locally and temporally photo-curable the polymerization type is very promising for 3D-printing. By using suitable wavelengths, photoinitiator-free fabrication is feasible for single- and two photon induced polymerization. In this paper divinyl ethers of polyethylene glycols in combination with star-shaped tetrathiols were used to design a simple test-system for photo-curable thiol-ene resins. In order to control and improve curing depth and lateral resolution in 3D-polymerization processes, either additives in chemical formulation or process parameters can be changed. The achieved curing depth and resolution limits depend on the applied fabrication method. While two-/multiphoton induced lithography offers the possibility of micron- to sub-micron resolution it lacks in built-up speed. Hence single-photon polymerization is a fast alternative with optimization potential in sub-10-micron resolution. Absorber- and initiator free compositions were developed in order to avoid aging, yellowing and toxicity of resulting products. They can be cured with UV-laser radiation below 300 nm. The development at Fraunhofer ILT is focusing on new applications in the field of medical products and implants, technical products with respect to mechanical properties or optical properties of 3D-printed objects. Recent process results with model system (polyethylene glycol divinylether/ Pentaerithrytol tetrakis (3-mercaptopropionat), Raman measurements of polymer conversion and surface modifications using bifunctional crosslinkers are presented with advantages, drawbacks and a general outlook.

The need for mechanical properties at elevated temperatures is high for finite element modelling, process optimization, research and development or quality assurance purposes. Obtaining of this data is difficult, for refractory materials such as molybdenum or tungsten reliable data including precise strain measurement is required up to 2500 °C. Over the last years a cooperation between PLANSEE and the University of Applied Sciences, Jena, Germany was built up. Within the internal research program “Basisdaten” (basic materials data) creep data and mechanical properties of molybdenum, tungsten and their alloys at very high temperatures could be achieved. After a description of the unique test equipment at the University of Applied Sciences, Jena, the results of creep and tensile tests on molybdenum and tungsten sheet material are presented.

Birch (Betula verrucosa) pollen-associated food allergy is a well-characterized syndrome, which is due to the cross-reactivity of IgE antibodies to homologous allergens in various foods. One crossreacting area on the major birch pollen allergen Bet v 1 and its homologue in cherry (Prunus avium) Pru av 1 has already been identified. This is the so-called ‘P-loop’ region, which encompasses amino acid residues around position 45 and is found on the two virtually identical tertiary protein structures. We tried to determine an additional IgE cross-reacting patch on Pru av 1 and Bet v 1. The putative IgE-binding region on Pru av 1 was localized with a mAb (monoclonal antibody) that was generated against Bet v 1, and cross-reacts with several Bet v 1 homologues in food and inhibits the binding of patients' IgE to Pru av 1. mAb reactivity pattern was analysed and amino acid positions 28 and 108 of Pru av 1 were selected and mutated by site-directed mutagenesis. The Pru av 1 mutants were produced as recombinant proteins and characterized for their folding, mAb- and IgE-binding capacity and allergenic potency with a cellular assay using the humanized rat basophilic leukaemia cell line RBL-25/30. Amino acid position 28 is involved in a second major IgE-binding region on Pru av 1 and probably on Bet v 1. The identification of this second major IgE-binding region is an essential prerequisite to understand the phenomenon of cross-reactivity and its clinical consequences, and to produce hypoallergenic proteins for an improved immunotherapy of type I allergy.

Gasformige und/oder flussige Abfalle aus chemischen Produktionsprozessen werden haufig in vergleichsweise kleinen dezentralen Ruckstandsverbrennungen direkt vor Ort entsorgt. Aufgrund der dabei entstehenden, mit Schadstoffen hoch belasteten Abgase werden mehrstufige, nassarbeitende Abgasreinigungssysteme eingesetzt, die in den meisten Fallen aus einem Quench, einen oder mehreren Nasswaschern sowie einer optionalen Aerosolabscheidung bestehen. Die Auswahl des geeigneten Reinigungssystems hangt neben den spezifischen technischen Randbedingungen besonders auch von wirtschaftlichen Gesichtspunkten ab, also den Investitions- und Betriebskosten. Daneben ist die Wahl geeigneter Apparatewerkstoffe entscheidend, insbesondere fur den Quenchapparat. Apparate und Verfahrensgrundkonzepte werden gegenuber gestellt und hinsichtlich wichtiger Eigenschaften quantitativ bzw. qualitativ verglichen. Gas Cleaning Systems of Decentralized Hazardous Waste Incinerators in the Chemical Industry In the chemical industry wet gas cleaning systems are frequently employed for the treatment of exhaust gases emerging from decentralized hazardous waste incinerators. With respect to the extremely high pollutant emissions, multistage gas cleaning processes are used that consist in most cases of a quench, one or more wet scrubbers and an optional aerosol separation stage. In order to select a suitable design of the gas cleaning process and equipment, beside the specific technical performance of each apparatus, particularly economic criteria have to be considered, like maintenance as well as investment costs. Additionally, the choice of the suitable material of construction plays a major role, especially at the transition section of dry to wetted gas in the quench. The present comparison of different process and equipment alternatives indicates that only the consideration of all relevant parameters yields to an optimal solution.

The paper deals with a unique continuous laboratory process for the manufacture of ultrathin nanofilms of various thermoplastic polymers, such as polycarbonate, polyetherimide, polysulfone, and liquid crystalline polyester, based upon the recently developed spontaneous film formation technique. Continuous films with a width up to 14 cm and a thickness of 20–100 nm were produced using a prototype laboratory apparatus at a windup velocity of 1–20 m/min. The length of the film can be almost infinite, i.e. longer than 1 km. The produced films are of high quality and can be used as layer materials, as membranes, in optical devices and sensors, as well as for microlithographic purposes. © 2003 Wiley Periodicals, Inc. Adv Polym Techn 22: 120–125, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10042

Polar lipid pattern determination is often used for the taxonomic classification of halophilic Archaea in addition to a genomic characterization. During the analysis of polar lipid extracts from the recently described haloarchaeon Natrononomonas moolapensis, an unknown glycolipid was detected. Fragmentation patterns observed from preliminary mass spectrometric analysis initially suggested the presence of a sulfo-hexosyl-phosphatidylglycerol. However, by NMR spectroscopy and enzymatic assays the existence of two isomeric molecules with different hexoses (1-(6-sulfo-d-glcp/galf-β1,2-glycero)-phospho-2,3-diphytanylglycerol) could be shown. The structural origin from phosphatidylglycerol distinguishes these glycolipids within Archaea, because all other characterized haloarchaeal glycolipids consist of diphytanylglycerol directly linked to an oligoglycosyl moiety. Now the door is open to investigate the physical and functional consequences of these architectural differences of the head groups. published

Objectifs de recherche : les depots atmospheriques de metaux lourds (ETM) et d'azote (N) peuvent avoir des effets a long terme sur la composition des especes des ecosystemes. Les forets sont particulierement touchees a cause du role de filtre de leur canopee. L'etude traite de l'effet de la rosee issue de la canopee sur l'accumulation d'azote et d'elements traces metalliques dans la mousse, utilisee comme bioindicateur des depots atmospheriques. Methodes : suivant le protocole experimental europeen pour les metaux lourds concernant la surveillance des mousses, l'azote et les metaux selectionnes ont ete determines dans les echantillons de mousse recoltes sur des sites avec et sans rosee issue de la canopee, dans le Nord-Ouest de l'Allemagne en 2012 (Kluge et al., 2013) et en 2013. La concentration en N a ete convertie en depot d'azote atmospherique (Schroder et al., 2014) pour identifier les depassements des charges critiques. Resultats : en comparant le depot estime d'azote atmospherique a la concentration d'azote dans les echantillons de mousse sur des sites sans rosee issue de la canopee (moyenne 2012 : 7,3 kg ha-1 an-1, 2013 : 10,9 kg ha-1 an-1), la moyenne d'azote atmospherique deposee sur des sites adjacents avec la presence d'une canopee etait environ trois fois plus elevee (2012 : 26,4 kg ha-1 an-1, 2013 : 31,1 kg ha -1 an- 1). Pour les 30 % des echantillons analyses avec canopee (moyenne sur les deux annees), la valeur des charges critiques donnee a ete depassee. Pour la concentration en ETM dans la mousse, pour le cadmium (Cd), le cuivre (Cu) , le mercure (Hg) , le plomb (Pb) et le zinc (Zn), la concentration dans la mousse etait egalement significativement plus elevee pour les sites avec canopee (moyennes sur plus deux ans : Cd 0,2 mg kg-1, Cu 8,5 mg kg -1, Hg 0,03 mg kg -1, Pb 2,7 mg kg -1, Zn 45,7 mg kg -1) que sur les sites sans canopee. Le chrome (Cr) et le nickel (Ni) ne presentaient aucune difference significative entre les deux types de sites. Principales conclusions : l'etude montre des variances spatiales significatives pour les concentrations d'azote et d'ETM. Celles-ci devraient etre prises en compte lors de cartographie et de modelisation des depots atmospheriques, ainsi que lors de la mise en œuvre des mesures pour reduire les depots atmospheriques.

For special advanced applications in medicine biomaterials can be tailor-made as composites if a single material is not able to fulfill the various requirements. In most cases a functional surface layer, which may have the required physical, mechanical, or biological properties, covers a structural material: titanium and its alloys for preference. Three classes of composites based on titanium materials offer special properties: Ti/porous Ti composites have special mechanical properties for isoelastic implants; Ti/ceramic composites show special biological properties used for improved osseointegration of the implants; and the special physical properties of Ti/ceramic composites makes them suitable for heart pacemaker leads.

Stability under digestion is thought to be an important prerequisite determining the allergenicity of food proteins. To test this hypothesis, two important allergenic plant-derived foods were selected for this investigation. Protein extracts from roasted peanuts and unprocessed (native) hazelnuts were digested by a static, two-step in vitro procedure with commercial enzyme tablets containing peptic and pancreatic enzymes, respectively. The food extracts were subjected to gastric digestion for 2 h followed by a 45-min treatment under duodenal conditions. Undigested control samples and the two digests were investigated by analytical sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), by SDS-PAGE immunoblotting, by an enzyme allergosorbent test (EAST) with human IgE, and by a rat basophil leukaemia (RBL) cell mediator release assay that depends on specific IgE raised in mice. Peanut proteins appeared to be more stable under digestion than hazelnut proteins, as shown by electrophoresis. These results were also underlined by immunblot data. The gastric digest from peanut contained various protein fragments that were detected by antibodies from a peanut-specific rabbit antiserum and by IgE from patients allergic to peanuts. These immunoblot reactivities decreased strongly after subsequent pancreatic digestion. In the gastric digest from hazelnuts, a rabbit antiserum with a broad reactivity against native hazelnut proteins exclusively recognized small protein fragments of

The combination of a new thermodesorption module with a cooled injection system now provides a powerful system for direct analysis of volatile trace compounds in gaseous, liquid and solid samples by gas chromatography–mass spectrometry (GC–MS). As a cooled injection system is used for the cryofocusing of the desorbed volatiles the GC–MS system still can be used for the regular analysis of liquid samples. Although plasticizers usually are analyzed by GC–MS after solvent extraction, contaminated solvents and glassware are very well known problems. Analysis of plasticizers in plastic materials by direct thermodesorption instead saves time and avoids cross contaminations. Many medical products are made of plasticized polyvinyl chloride. Extraction of the common plasticizer di(2-ethylhexyl) phthalate (DEHP) into blood will occur, and harmful effects of DEHP in the human body have been suggested. We therefore analyzed 21 different plastic devices which are used for various invasive techniques in medicine by direct thermodesorption GC-MS. In some of the plastics up to 30 different components were identified. By far the most common plasticizer found was DEHP, followed by diethyl and dibutyl phthalates.

A multipurpose sampler (Gerstel MPS), designed for liquid large volume, gaseous and headspace samples was used for the GC-MS analysis of organic volatiles in human urine. Headspace sampling with a volume-, temperature- and speed-controlled gas-tight syringe was combined with a temperature-controlled cold injection system (CIS) for cold trapping, enrichment and focusing of analytes. Regular 2-ml GC vials filled with 1 ml acidified urine were used as headspace sampling vials. A 100-vial autosampler tray was equipped with an additional temperature and heating time controlled "preheating station" for five vials. Profiles of organic volatiles in human urine were determined and 34 components identified. Trimethylamine (TMA) and 4-heptanone as two metabolites of medical interest were quantified. Calibration curves and intra assay imprecision for 4-heptanone concentrations in the range of 40 to 800 ng/ml showed a correlation coefficient of r = 0.9980 and a relative standard deviation (RSD) between 3.0 and 3.4%. Calibration curves and intra-assay imprecision for TMA concentrations in the range of medical interest from 0.5 to 20 micrograms/ml showed a correlation coefficient of r = 0.9968 and a RSD between 4.1 and 6.8%. The high practicability of the multipurpose sampler for both gaseous and liquid samples together with the here shown good reproducibility and sensitivity make this single CIS-GC-MS system very attractive for routine clinical use in metabolic profiling of organic volatiles (headspace) and non-volatiles (liquid).

Generation and trapping (counter ion) of the phosphavinyl cation (the P-analog of vinyl cation) by low temperature protonation of kinetically stable phosphaalkynes in super acid media led to the formation of the corresponding phosphaalkenes without direct observation of a long-lived cation. Reactions of RCP (R = tBu, 1-Ad) with “PhSeF” and with PhSeCl resulted in bis-phenylselenenylation and chlorophenylselenenylation respectively, forming novel Se-containing phosphaalkenes. Ionization of 1-H-triflato-phosphirene with B(OTf) 3 /SO2 led to the direct observation of a persistent phosphirenylium cation. The (CO)5 W-complexed phosphirenylium cation was subsequently generated from the (CO)5 W-complexed triflate and trifluoroacetate derivatives. Progress in P-functionalization of tetraphosphacubane by reactions with potent electrophiles (i.e. MeOTf, EtOTf“PhCH2OTf”, TMSCH2OTf), alkynyl-iodonium triflates and with protic superacids are briefly summarized.

Soybeans are known to be allergenic for adults as well as for infants. Processed products derived from soybeans are used in a wide spectrum of foods, drugs and other industrial products. In particular, soybean lecithins are used as stabilizers and emulsifiers and may not be suspected as possible source of allergens. To test this hypothesis, six commercial soy lecithins were investigated for residual allergenicity and compared with extracts from raw and heat-treated soybeans. They were characterized, the protein content was determined by enzyme-linked immunosorbent assay (ELISA) and allergens were analyzed with specific IgE from patients' sera using the enzyme allergosorbent test (EAST), EAST inhibition and protein blotting followed by immunodetection. For further characterization a polyclonal antiserum directed against soybean extract and a monoclonal antibody (mAb 025) directed against the acidic subunit of the soybean storage protein glycinin were used. The EAST studies revealed that three of six sera from patients with allergy to soybeans contained IgE to four soy lecithins (Topcithin 50, Topcithin 300, Emulfluid FD 12, Epikuron 100 P), the same lecithins which were found to contain residual proteins. Two lecithins with a protein content of less than 20 ppb did not bind IgE. EAST inhibition showed that the allergens from soy lecithin were immunologically more closely related to allergens from heat-treated soybeans than to those from raw soybeans. Protein blotting and immunodetection of the protein extract from the lecithins resulted in various allergen bands between 14 kDa and 94 kDa. A heat-stable allergen of 39 kDa was recognized by the monoclonal antibody and thus identified as a subunit of glycinin. The results obtained were confirmed by a mediator release assay based on a rat basophil leukemia cell line. Lecithins that contained residual proteins caused a specific mediator release, suggesting that these products may induce allergic symptoms. Our results show that soybean lecithins are capable of introducing hidden allergens to processed foods and that the IgE binding potential corresponds to the total protein determined by ELISA. Furthermore, it appears to be possible that by monitoring the protein content soy lecithins can be applied which may be safe for the allergic consumer.

Food extracts for diagnostic purposes often lack sufficient activity and consistency. Biologically standardized food extracts are not available on the market. Using extracts from plant-derived foods as examples, we investigated factors which may be important for the quality of such extracts. Divergent allergenic activities were found between strains of apples, but not within varieties of celery tuber (celeriac), hazelnut, and peanut, respectively. Heating of the food remarkably reduced the activity of apple, hazelnut, and celeriac, but had little effect on peanut. By contrast, heating of semipurified protein extracts from celery tuber and apple for 30 min at 100 degrees C did not deplete the immunoreactivity of the major allergens, indicating that this is an inappropriate test for identifying labile food allergens. Due to their high endogenous enzyme activities, apples and other fruits require special extraction procedures applying either low temperature or enzyme inhibitors. Variation of extraction conditions had little effect on the composition and activity of extracts from hazelnut. The storage stability of skin test solutions from plant foods can be improved by avoiding phenol as an additive and by including 50% of glycerol. For model studies considering neoallergens, IgE was raised in mice against native and heated celery tuber, respectively. When extracts from nonthermally and thermally processed celeriac were subjected to an RBL-cell mediator release assay with these sera, an inverse ranking was obtained with anti-heated celeriac IgE and anti-native celeriac IgE, respectively. These data indicated that new epitopes had been formed by the heating process. Since all parameters were tested in model experiments with either human or murine IgE, their relevance has to be proven in further clinical investigations.

Peanuts are one of the most allergenic foods known. The presence of hidden allergens in processed food for reasons of mislabelling or cross-contamination expose allergic individuals to unpredictable risks, especially since highly sensitized subjects may experience severe anaphylactic reactions. The protection of consumers requires specific and sensitive methods for the detection of trace amounts of potentially allergenic peanut components. A rocket immunoelectrophoresis (RIE) procedure was developed allowing the detection of even spurious contaminations with peanut protein. For precipitation of peanut protein a commercially available antiserum was used. By amplifying precipitates with a secondary immunodetection step, 20 ng/ml peanut protein in chocolate extract, equivalent to 0.0002% peanut in chocolate, could still be detected. Model chocolate spiked with various amounts of peanut was investigated down to 0.001% peanut (10 ppm), the limit of quantitative determination. The method was optimized for detection of peanut in chocolate samples. Non-chocolate samples had to be standardized with a chocolate matrix prior to analysis in order to obtain a uniform response. Cross-reactivities with other food proteins did not occur. The method showed high recoveries of 85–101% for chocolate samples down to 10 ppm peanut and good reproducibility with coefficients of variation of ≤ 5 % for samples of ≥ 15 ppm peanut protein. The applicability of this method in the detection of peanut protein in various food commodities was demonstrated: two unlabelled products and two products which did not have peanut listed as an ingredient were identified as containing peanut protein. In all cases where peanut was listed, peanut protein could be determined. The results of RIE were always confirmed by those of a new cell-mediator-release assay that is based on a rat basophil leukaemia (RBL) cell-line (RBL-2H3), cells that are a functional equivalent to mucosal mast cells. Measuring the release of β-hexosaminidase resulting from cross-linking of basophil-bound peanut-specific immunoglobulin E, the assay mimics a main event of the allergic type-I reaction. The cell assay was adapted for food matrices and peanut could be detected down to 0.01% which additionally demonstrated in vitro that even trace amounts of peanut protein could elicit allergic reactions.