Our innate immune system distinguishes microbes from self by detecting conserved pathogen-associated molecular patterns. However, these are produced by all microbes, regardless of their pathogenic ...potential. To distinguish virulent microbes from those with lower disease-causing potential the innate immune system detects conserved pathogen-induced processes, such as the presence of microbial products in the host cytosol, by mechanisms that are not fully resolved. Here we show that NOD1 senses cytosolic microbial products by monitoring the activation state of small Rho GTPases. Activation of RAC1 and CDC42 by bacterial delivery or ectopic expression of SopE, a virulence factor of the enteric pathogen Salmonella, triggered the NOD1 signalling pathway, with consequent RIP2 (also known as RIPK2)-mediated induction of NF-κB-dependent inflammatory responses. Similarly, activation of the NOD1 signalling pathway by peptidoglycan required RAC1 activity. Furthermore, constitutively active forms of RAC1, CDC42 and RHOA activated the NOD1 signalling pathway. Our data identify the activation of small Rho GTPases as a pathogen-induced process sensed through the NOD1 signalling pathway.
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DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Ternary Fe–Cr–Mo alloys, all containing about 2at.% total alloying element content (Cr+Mo) but with atomic Cr/Mo-ratios ranging from 1.0 to 7.2, were nitrided at 580°C, 550°C, and 520°C. The nitrided ...zone was characterized by light microscopy, hardness measurements, electron probe microanalysis and X-ray diffraction. The alloying element nitrides forming in the nitrided zone were characterized by scanning and transmission electron microscopy. Initially, the continuous precipitation of finely distributed, “mixed”, cubic NaCl-type (Cr,Mo)Ny nitride platelets, exhibiting a Baker–Nutting orientation relationship with the ferrite matrix, occurs. The developing N-concentration-depth profiles indicate that alloys with a lower Cr/Mo-ratio show a slightly slower nitride-precipitation rate. The attainable surface hardness and the residual surface macrostress are of similar magnitudes for all Cr/Mo-ratios. Upon prolonged nitriding (=aging of the nitrided microstructure), a discontinuous transformation takes place leading to the formation of a coarsened lamellar microstructure. The nature of this discontinuous reaction changes from a discontinuous coarsening of the initial (Cr,Mo)Ny nitride platelets for alloys of high Cr/Mo-ratios to a discontinuous precipitation of hexagonal CrMoN2 for alloys of low Cr/Mo-ratios. The latter reaction, as compared to the first one, is driven by a larger driving force and thus the extent of the discontinuous transformation increases considerably with decreasing Cr/Mo-ratio. A summarizing discussion on precipitation of “mixed” vs. separate nitrides is presented.
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•Huge effect of variation of the Cr/Mo ratio on nitriding and microstructural response of Fe–Cr–Mo alloys•Demonstration of competition of discontinuous coarsening and discontinuous precipitation•Tremendous hardening achievable by nitriding of Fe–Cr–Mo alloys
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
To explain the variance in core hardness of 18CrNi8 nozzle bodies after industrial heat treatment, several data sources, including steel melt composition, sensor process data, and measurement errors, ...of five years are aggregated. In order to predict hardness variations caused by alloy composition, traditional physical models by Maynier are compared with data‐driven machine learning models, which show no advantage due to low data variability. Neither method can fully explain the visible drifts, which are better tracked by an alternative (i. e., filter model) that uses past measurements. Machine learning on features from heat treatment is not successful in predicting hardness change, presumably because the process is too stable. Finally, a large part of the variance is caused by the HV 1 measurement error.
Translation
Um die Varianz der Kernhärte von Düsenkörpern aus 18CrNi8 nach einer industriellen Wärmebehandlung zu erklären, werden mehrere Datenquellen, darunter die Werkstoffzusammensetzung der Stahlschmelze, die Prozessdaten der Sensoren sowie die Messfehler, der vergangenen fünf Jahren kombiniert und analysiert. Zur Vorhersage von Härteänderungen, die durch die Werkstoffzusammensetzung verursacht werden, werden traditionelle physikalische Modelle von Maynier datengetriebenen maschinellen Lernmodellen gegenübergestellt. Keine der beiden Methoden kann die sichtbaren Drifts vollständig erklären, die durch ein alternatives Filtermodell, das vergangene Messungen verwendet, besser erfasst werden. Maschinelles Lernen auf Basis von Merkmalen aus der Wärmebehandlung ist bei der Vorhersage der Härteänderung nicht erfolgreich; vermutlich aufgrund der hohen Prozessstabilität und der damit einhergehenden zu geringen Varianz. Schließlich wird ein großer Teil der insgesamt zu beobachtenden Varianz durch die Streuung der HV 1 Messung verursacht.
Data sources, including steel melt composition, meta and sensor process data, as well as measurement errors are used to explain the variance in core hardness of 18CrNi8 nozzle bodies after industrial heat treatment. Traditional physical models are compared with data‐driven machine learning models in order to predict deviation of core hardness from the reference.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Nitriding of recrystallized and cold-rolled Fe-1 at. pct Mo alloy at 853 K (580 °C) in a NH
3
/H
2
gas mixture leads to the formation of cubic nanometer-sized Mo
2
N-type precipitate platelets. These ...platelets obey a Baker–Nutting orientation relationship with the ferrite matrix. After prolonged nitriding, micrometer-sized colonies of lamellae consisting of a hexagonal MoN-type nitride and ferrite develop in a discontinuous precipitation reaction. These nitride lamellae have a Burgers-type orientation relationship with the ferrite lamellae. As compared to the recrystallized specimens, in the cold-rolled specimens, the precipitation of the initial Mo
2
N-type platelets occurs much faster and moreover leads to incoherently diffracting precipitates; upon continued nitriding, a much earlier but only partially occurring transition of Mo
2
N-type to MoN-type precipitates is observed. The results indicate that incorporation of iron in the nitrides can occur, if at all, only up till a negligible level, thereby invalidating earlier data.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The microstructure and the kinetics of growth of the nitrided zone of a Mo-containing maraging steel were investigated by performing gaseous nitriding at temperatures between 713 K (440 °C) and 793 K ...(520 °C) and at nitriding potentials up to 0.5 atm
−1/2
for both solution-annealed and precipitation-hardened specimens. The microstructure of the nitrided zone was investigated by means of X-ray diffraction (phase constitution; crystal imperfection). Fine, initially largely coherent Mo
2
N-type precipitates developed in the nitrided zone. The elemental concentration-depth profiles were determined employing glow discharge optical emission spectroscopy (GDOES). The nitrogen content within the nitrided zone exceeds the nitrogen content expected on the basis of the molybdenum content and the equilibrium solubility of nitrogen in a (stress-free) ferritic matrix: excess nitrogen occurs. A numerical model was applied to predict the nitrogen concentration-depth profile within the nitrided layer. The model describes the dependence on time and temperature of the nitrogen concentration-depth profiles with, as fit parameters, the surface nitrogen concentration, the diffusion coefficient of nitrogen in the matrix, a composition parameter of the formed nitride and the solubility product of the nitride-forming element and dissolved nitrogen in the matrix. Initial values for the surface nitrogen concentration and the composition parameter were determined experimentally with an absorption isotherm and fitted to the measured nitrogen concentration-depth profiles. The results obtained revealed the striking effects of the amount of excess nitrogen and the extent of precipitation hardening on the developing nitrogen concentration-depth profile.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Upon nitriding of binary Fe-1 at.% Mo alloy in a NH
3
/H
2
gas mixture under conditions (thermodynamically) allowing γ′-Fe
4
N
1-
x
compound layer growth (nitriding potential: 0.7 atm
−1/2
at 753 K ...(480 °C) - 823 K (550 °C)), a strong dependency of the morphology of the formed compound layer on the defect density of the specimen was observed. Nitriding of cold-rolled Fe-1 at.% Mo specimens leads to the formation of a closed compound layer of approximately constant thickness, comparable to nitriding of pure iron. Within the compound layer, that is, in the near-surface region, Mo nitrides are present. The growth of the compound layer could be described by a modified parabolic growth law leading to an activation energy comparable to literature data for the activation energy of growth of a γ′-Fe
4
N
1−
x
layer on pure iron. Upon low temperature nitriding (i.e. ⩽793 K (520 °C)) of recrystallized Fe-1 at.% Mo specimens, an irregular, 'needle-like' morphology of γ′-Fe
4
N
1−
x
nucleated at the surface occurs. This γ′ iron nitride has an orientation relationship (OR) with the matrix close to the Nishiyama-Wassermann OR. The different morphologies of the formed compound layer can be interpreted as consequences of the ease or difficulty of precipitation of Mo as nitride as function of the defect density.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
14,000 data sets from an industrialized bainitization process, consisting of process gas furnace, salt bath and circulating air furnace, were used to predict the resulting Vickers hardness of ...cylinder heads made of 100Cr6 based on process data such as temperature and pressure. For prediction, machine learning methods such as ANNs, CNNs, ensemble methods and support vector regressors were compared. Meta features such as the furnace number as well as features extracted from the recorded time series were used. Data preparation and feature extraction were performed according to the machine learning methods used. The random forest achieved the best predictions with an R
score of 0.406 and also allows the evaluation of the most important features.
For the calorimetric determination of the primary energy of extensive air showers, measured by fluorescence telescopes, a precise knowledge of the conversion factor (fluorescence yield) between the ...deposited energy in the atmosphere and the number of emitted fluorescence photons is essential. The fluorescence yield depends on the pressure and the temperature of the air as well as on the water vapor concentration. Within the scope of this work the fluorescence yield for the eight strongest nitrogen emission bands between 300
nm and 400
nm has been measured using electrons from a
90Sr-source with energies between 250
keV and 2000
keV. Measurements have been performed in dry air, pure nitrogen, and a nitrogen–oxygen mixture at pressures ranging from 2
hPa to 990
hPa. Furthermore the influence of water vapor has been studied. A new approach for the parametrization of the fluorescence yield was used to analyze the data, leading to a consistent description of the fluorescence yield with a minimal set of parameters. The resulting absolute accuracies for the single nitrogen bands are in the order of 15%. In the investigated energy range, the fluorescence yield proved to be independent of the energy of the ionizing electrons.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The fluorescence detection of ultra high energy (≳10
18
eV) cosmic rays requires a detailed knowledge of the fluorescence light emission from nitrogen molecules, which are excited by the cosmic ray ...shower particles along their path in the atmosphere. We have made a precise measurement of the fluorescence light spectrum excited by MeV electrons in dry air. We measured the relative intensities of 34 fluorescence bands in the wavelength range from 284 to 429
nm with a high resolution spectrograph. The pressure dependence of the fluorescence spectrum was also measured from a few hPa up to atmospheric pressure. Relative intensities and collisional quenching reference pressures for bands due to transitions from a common upper level were found in agreement with theoretical expectations. The presence of argon in air was found to have a negligible effect on the fluorescence yield. We estimated that the systematic uncertainty on the cosmic ray shower energy due to the pressure dependence of the fluorescence spectrum is reduced to a level of 1% by the AIRFLY results presented in this paper.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Niederdruck-Carbonitrieren mit Aminen Koch, D.; Hagymási, L.; Waldenmaier, T. ...
Journal of heat treatment and materials : HTM = Zeitschrift für Werkstoffe, Wärmebehandlung, Fertigung,
08/2015, Volume:
70, Issue:
4
Journal Article
ist ein modernes Verfahren zum Einsatzhärten von niedriglegierten Einsatzstählen. Bei ihm werden Kohlenstoff und Stickstoff bei Gesamtdrücken von kleiner 50 mbar und bei Temperaturen über 800 °C in ...der Randschicht der zu behandelnden Werkstücke angereichert. In der Literatur wird fast ausschließlich Ammoniak als Stickstoffdonator, in Verbindung mit einem Kohlenstoffdonator, meist Ethin oder Propan, als Prozessgas diskutiert 1–3. Der Einsatz anderer Gase bzw. Gasmischungen als Donatoren für Kohlenstoff und Stickstoff sowie deren Wirksamkeit bei der Anreicherung der Randschicht mit den genannten Elementen wird so gut wie nicht behandelt. Am Engler-Bunte-Institut des Karlsruher Instituts für Technologie wurden daher potenzielle Prozessgase für das Niederdruck-Carbonitrieren identifiziert. Deren Wirksamkeit beim Anreichern einer Bauteils-Randschicht mit Kohlenstoff und Stickstoff wurde in einer Thermowaage experimentell untersucht. Mit Methylamin (CH
NH
) und Dimethylamin ((CH
NH) konnten zwei Prozessgase gefunden werden, die im Vergleich zu Ammoniak in Verbindung mit einem Kohlenstoffdonator (z. B. Ethin, Propan) zu einer guten Anreicherung der Randschicht mit Kohlenstoff und Stickstoff führen. Auf Basis einer vorangegangenen Potenzialanalyse werden in der vorliegenden Veröffentlichung ausschließlich Untersuchungsergebnisse zum Niederdruck-Carbonitrieren mit Methylamin vorgestellt.
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