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Eingeladener Vortrag
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Eight commercial austenitic stainless steels were tensile tested in reference atmosphere, in gaseous high-pressure hydrogen and in gaseous hydrogen precharged condition using conventional (CS) and tubular specimens (TS). For all configurations, 0.2 yield strength and ultimate tensile strength were comparable. In reference atmosphere, reduction of area of CS was higher compared to TS, whereas in gaseous high pressure hydrogen reduction of area of CS was lower compared to TS. In gaseous hydrogen precharged condition reduction of area of CS and TS were comparable for the severely affected grades. The differences in necking behavior between CS and TS are explained by different competitions between necking and hydrogen assisted crack initiation and growth especially for the tests in high pressure hydrogen gas.
Die nicht ionisierende elektromagnetische Strahlung im Bereich von Terahertz-Frequenzen ermöglicht berührungslose und zerstörungsfreie Mess- und Prüftechnik in zahlreichen Bereichen. Nach ersten Anwendungen in der Astronomie und der Atmosphärenforschung wurden in letzter Zeit Anwendungsfelder in der Sicherheitstechnik, der Medizintechnik, der Nachrichtentechnik und der zerstörungsfreien Prozess- und Qualitätskontrolle erschlossen. Dielektrische Materialien wie Kunststoffe und Keramiken können von Terahertz-Wellen durchdrungen werden. Das ermöglicht Untersuchungen des Objektinneren ohne spezielle Schutzmaßnahmen, wie sie z.B. beim Röntgen notwendig sind. Die Richtlinie erleichtert die Verständigung zwischen Nutzern, Herstellern und dem Vertrieb von Terahertz-Systemen. In der Richtlinie werden bekannte Einsatzgebiete sowie die eingesetzten Verfahren und Funktionsprinzipien aufgeführt, um den Leser bei der Auswahlentscheidung zu unterstützen. Nach einer kurzen Einführung in die physikalischen Grundlagen und Hinweisen zur elektromagnetischen Verträglichkeit, zum Strahlenschutz und zur regulierten Frequenzvergabe werden die verschiedenen Geräteklassen von Terahertz-Systemen ausführlich vorgestellt. Die Richtlinie gibt Hinweise zur messtechnischen Charakterisierung von Terahertz-Wellen. Einsatzgebiete von Terahertz-Systemen, wie die zerstörungsfreie Prüfung, die Dicken- und Abstandsmessung, die Tomografie und die chemische Analytik, werden mit ihren spezifischen Eigenschaften im Detail beschrieben. Umfangreiche Literaturverweise vereinfachen eine vertiefte Beschäftigung mit den Themen der Richtlinie. Eine tabellarische Übersicht mit einer Zusammenfassung, welche Terahertz-Systeme für welche Anwendungsfelder eingesetzt werden können, vervollständigt die Richtlinie.
Diese Richtlinie definiert Kenngrößen und Messverfahren, um Terahertzsysteme für die Zeitbereichsspektroskopie (TDS)zu spezifizieren. So können Hersteller ihre Systeme übereinstimmend beschreiben und Anwender einfach Systeme vergleichen. Systeme für die Terahertz-Zeitbereichsspektroskopie sind aktive Systeme und nutzen verschiedene Techniken sowohl zur Erzeugung als auch zur zeitaufgelösten Messung von breitbandigen Terahertzimpulsen. Die dazugehörigen Terahertzspektren und -Phasen werden nach einer zeitlichen Abtastung über eine Fourier-Transformation berechnet. In dieser Richtlinie wird ein Überblick über die Funktionsweisen von Zeitbereichsspektrometern gegeben, die eingesetzten Messverfahren näher erläutert sowie die benötigten Begriffe und Kenngrößen definiert. Die Richtlinie konzentriert sich dabei auf Systeme, die auf sogenannten Abtastmessverfahren (Sampling-Messverfahren) basieren.
Flame retarded poly(butylene terephthalate) (PBT) is required for electronic applications and is mostly achieved by low molar mass additives so far. Three phosphorus-containing polyesters are suggested as halogen-free and polymeric flame retardants for PBT. Flame retardancy was achieved according to cone calorimeter experiments showing that the peak heat release rate and total heat evolved were reduced because of flame inhibition and condensed-phase activity. The presented polymers containing derivatives of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide form immiscible blend systems with PBT. Shear-rheology shows an increase in storage moduli at low frequencies. This is proposed as quantitative measure for the degree of phase interaction. The phase structure of the blends depends on the chemical structure of the phosphorus polyester and was quite different, depending also on the viscosity ratio between matrix and second phase. A lower viscosity ratio leads to two types of phases with spherical and additionally continuous droplets. Addition of the flame retardants showed no influence on the dielectric properties but on the mechanical behavior. The polymeric flame retardants significantly diminish the impact strength because of several reasons: (1) high brittleness of the phosphorus polyesters themselves, (2) thermodynamic immiscibility, and (3) weak phase adhesion. By adding a copolymer consisting of the two base polymers to the blend, an improvement of impact strength was obtained. The copolymer particularly acts as compatibilizer between the phases and therefore leads to a smaller phase size and to a stronger phase adhesion due to the formation of fibrils.
The collaborative project “Impacts of impurities in CO2 streams captured from different emitters in a regional cluster on transport, injection and storage (CLUSTER)” aimed to set up recommendations on how to define “reasonable minimum composition thresholds” that CO2 streams should meet when accessing CO2 transport pipeline networks. Within CLUSTER, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the whole CCS chain. Investigations included, amongst others, impacts on: Corrosion of pipeline steel, pipeline network design and related transport costs, alteration of well bore cements, pressure development and rock integrity, geochemical reactions, and petrophysical and geomechanical rock properties.
All investigations are based on a generic CCS chain scenario. In this scenario, CO2 streams are captured from a spatial cluster of eleven emitters and collected in a regional pipeline network. Emitters comprise seven fossil fuel-fired power plants equipped with different capture technologies, two cement plants, one refinery and one integrated iron and steel plant. In total, 19.78 Mio t CO2 (including impurities) are captured in the emitter cluster annually. The combined CO2 stream is transported in a trunk line with a length of 400 km (100 km of these offshore) and is injected into five generic storage structures. The storage reservoirs are saline aquifers of the Buntsandstein.
The investigations revealed beneficial and deteriorating impacts of different impurities and combinations thereof. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the modelled variable compositions and mass flow rates were observed. Based on the results, the CLUSTER project team recommends not to define “minimum composition thresholds” for CO2 streams as strict threshold values for each individual impurity in the stream. Instead, CO2 stream compositions and variabilities for specific CCS projects should be constrained with regard to a set of parameters including i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of CO2 stream composition, and iv) impurity combinations to be avoided.
Fourteen hollow and one cast anthropomorphic and zoomorphic figurines produced in Incan times for ritual offerings from the Ethnologisches Museum in Berlin were selected to investigate the technologies and alloys used for their fabrication with portable optical microscopy and non-destructive XRF elemental analysis. This group of gold and silver figurines includes typical specimens of the Inca production, such as the four silver figurines from the Island Coati in Lake Titicaca and the two gold figurines from Pachacamac, as well as specimens that are seldom present in collections, which makes them atypical. In addition to the tall figurines with atypical hair or standing pose, one bicolour figurine half silver, half gold) and another with coloured inlays were included in this study for comparison. The large majority of the silver specimens are made from very high quality alloys and the gold figurines are made from alloys containing low copper contents and silver ranging from 30wt% to 52wt%.
3-Aminovinylquinoxalines are readily accessible from (hetero)aryl glyoxylic acids or heterocyclic π-nucleophiles by consecutive four- and fivecomponent syntheses in the sense of an activation-alkynylation-cyclocondensation-addition sequence or glyoxylation-alkynylation-cyclocondensation-addition sequence in good yields. The title compounds are highly fluorescent with pronounced emission solvatochromicity and protochromic fluorescence quenching. Time-resolved fluorescence spectroscopy furnishes radiative and nonradiative fluorescence decay rates in various solvent polarities. The electronic structure is corroborated by DFT and TD-DFT calculations rationalizing the observed spectroscopic effects.
The collaborative project “Impacts of impurities in CO2 streams captured from different emitters in a regional cluster on transport, injection and storage (CLUSTER)” aimed to set up recommendations on how to define “reasonable minimum composition thresholds” that CO2 streams should meet when accessing CO2 transport pipeline networks. Within CLUSTER, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the whole CCS chain. Investigations included, amongst others, impacts on:
• corrosion of pipeline steel,
• pipeline network design and related transport costs,
• alteration of well bore cements,
• pressure development and rock integrity,
• geochemical reactions, and
• petrophysical and geomechanical rock properties.
All investigations are based on a generic CCS chain scenario. In this scenario, CO2 streams are captured from a spatial cluster of eleven emitters and collected in a regional pipeline network. Emitters comprise seven fossil fuel-fired power plants equipped with different capture technologies, two cement plants, one refinery and one integrated iron and steel plant. In total, 19.78 Mio t CO2 (including impurities) are captured in the emitter cluster annually. The combined CO2 stream is transported in a trunk line with a length of 400 km (100 km of these offshore) and is injected into five generic storage structures. The storage reservoirs are saline aquifers of the Buntsandstein.
The investigations revealed beneficial and deteriorating impacts of different impurities and combinations thereof. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the modelled variable compositions and mass flow rates were observed. Based on the results, the CLUSTER project team recommends not to define “minimum composition thresholds” for CO2 streams as strict threshold values for each individual impurity in the stream. Instead, CO2 stream compositions and variabilities for specific CCS projects should be constrained with regard to a set of parameters including i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of CO2 stream composition, and iv) impurity combinations to be avoided.