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During R/V Meteor cruise 141/1, pore fluids of near surface sediments were investigated to find indications for hydrothermal activity in the Terceira Rift (TR), a hyperslow spreading center in the Central North Atlantic Ocean. To date, submarine hydrothermal fluid venting in the TR has only been reported for the D. João de Castro seamount, which presently seems to be inactive. Pore fluids sampled close to a volcanic cone at 2,800‐m water depth show an anomalous composition with Mg, SO4, and total alkalinity concentrations significantly higher than seawater and a nearby reference core. The most straightforward way of interpreting these deviations is the dissolution of the hydrothermally formed mineral caminite (MgSO4 0.25 Mg (OH)2 0.2H2O). This interpretation is corroborated by a thorough investigation of fluid isotope systems (δ26Mg, δ30Si, δ34S, δ44/42Ca, and 87Sr/86Sr). Caminite is known from mineral assemblages with anhydrite and forms in hydrothermal recharge zones only under specific conditions such as high fluid temperatures and in altered oceanic crust, which are conditions generally met at the TR. We hypothesize that caminite was formed during hydrothermal activity and is now dissolving during the waning state of the hydrothermal system, so that caminite mineralization is shifted out of its stability zone. Ongoing fluid circulation through the basement is transporting the geochemical signal via slow advection toward the seafloor.
Two types of cements were selected as the reference cement in the priority program 2005 of the German Research Foundation (DFG SPP 2005). A thorough characterization of CEM I 42.5 R has been made in a recent publication. In this paper, the characterization data of the other reference cement CEM III/A 42.5 N are presented from the aspects of chemical and mineralogical compositions as well as physical and chemical properties. The characterization data of the slag, which is the second main constituent of this specific cement besides the clinker, are presented independently. For all data received, the mean values and the corresponding errors were calculated. The data shall be used for the ongoing research within the priority program. Also, researchers from outside this priority program can benefit from these data if the same materials are used.
A number of very relevant processes for protection and reconstruction of buildings can be supported by controlled heating: elimination of pests without using hazardous Chemicals, drying and decontamination of timber and many other building materials. For this purpose, radio-frequency (RF) dielectric heating is an advantageous Option because the materials and structures can be heated directly by energy absorption in the volume, homogeneously and, if required, relatively fast.
Compared to microwaves, the penetration depths are usually much larger and the flexibility with respect to different materials is wider. Namely, heating can also be realized for dry materials because the dielectric loss is as not closely related to the presence of water as for microwave applications.
Die thermische Bekämpfung von Holzschädlingen erfordert wegen der geringen Wärmeleitfähigkeit von Holz lange Behandlungszeiten und kann zur Rissbildung führen. Hier wurde die thermische Behandlung mittels Radio- und Mikrowellen untersucht. Die direkte, dielektrische Erwärmung hat den Vorteil einer größeren Homogenität der Aufheizung. Die mit Radiowellen erzielten Temperaturprofile waren homogener als die mit Mikrowellen realisierten. Untersuchungen zeigten, dass die Abtötung nicht auf die direkte Einwirkung von elektromagnetischen Feldern, sondern auf die Temperaturerhöhung zurückzuführen ist.-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Thermal pest control requires long treatment times due to the low thermal conductivity of wood and may lead to the formation of cracks. Here, the thermal treatment with radio waves as well as microwaves has been studied. The direct dielectric heating has the advantage of a good homogeneity. The obtained temperature profiles for radio waves were more homogeneous compared to microwaves. Detailed studies showed that elimination of pests was not related to the application of the electromagnetic field itself, but due to the temperature increase.
Pathogenic Gram-negative bacteria use a type three secretion system (TTSS) to deliver virulence factors into host cells. Although the order in which proteins incorporate into the growing TTSS is well described, the underlying assembly mechanisms are still unclear. Here we show that the TTSS needle protomer refolds spontaneously to extend the needle from the distal end. We developed a functional mutant of the needle protomer from Shigella flexneri and Salmonella typhimurium to study its assembly in vitro. We show that the protomer partially refolds from α-helix into β-strand conformation to form the TTSS needle. Reconstitution experiments show that needle growth does not require ATP. Thus, like the structurally related flagellar systems, the needle elongates by subunit polymerization at the distal end but requires protomer refolding. Our studies provide a starting point to understand the molecular assembly mechanisms and the structure of the TTSS at atomic level.
This paper presents the results of an interlaboratory study of the rheological properties of cement paste and ultrasound gel as reference substance. The goal was to quantify the comparability and reproducibility of measurements of the Bingham parameters yield stress and plastic viscosity when measured on one specific paste composition and one particular ultrasound gel in different laboratories using different rheometers and measurement geometries.
The procedures for both in preparing the cement paste and carrying out the rheological measurements on cement paste and ultrasound gel were carefully defined for all of the study’s participants. Different conversion schemes for comparing the results obtained with the different measurement setups are presented here and critically discussed. The procedure proposed in this paper ensured a reasonable comparability of the results with a coefficient of variation for the yield stress of 27% and for the plastic viscosity of 24%, despite the individual measurement series’ having been performed in different labs with different rheometers and measurement geometries.
A thorough characterization of starting materials is the precondition for further research, especially for cement, which contains various phases and presents quite a complex material for fundamental scientific investigation. In the paper at hand, the characterization data of the reference cement CEM I 42.5 R used within the priority program 2005 of the German Research Foundation (DFG SPP 2005) are presented from the aspects of chemical and mineralogical compositions as well as physical and chemical properties. The data were collected based on tests conducted by nine research groups involved in this cooperative program. For all data received, the mean values and the corresponding errors were calculated. The results shall be used for the ongoing research within the priority program.
Chemical-free pest control by dielectric
heating with radio waves and microwaves:
Thermal effects
(2018)
Thermal pest control with hot air is widely accepted as an alternative to chemical methods. However, it requires relatively long treatment times owing to the low thermal conductivity of wood. Direct dielectric heating that applies radio waves or microwaves has the advantage of more homogeneous heating. However, Sound experimental data on this technique are currently rare. Therefore, the thermal treatment of wood-destroying insects with radio waves and microwaves was studied with two model pests, Anobium punctatum and Hylotrupes bajulus, and with Tenebrio molitor as a reference. The secure elimination of pests was achieved, and the corresponding treatment time was in the range of a few minutes. Temperature profiles were more homogeneous when applying radio waves.
A thorough characterization of base materials is the prereq- uisite for further research. In this paper, the characterization data of the reference materials (CEM I 42.5 R, limestone pow- der, calcined clay and a mixture of these three components) used in the second funding phase of the priority program 2005 of the German Research Foundation (DFG SPP 2005) are presented under the aspects of chemical and min- eralogical composition as well as physical and chemical properties. The data were collected based on tests performed by up to eleven research groups involved in this cooperative program.
Innovative Technologien für die Erkundung, Löschung und Beobachtung von Kohlebränden - Phase B -
(2011)
Aufbauend auf den Erkenntnissen der Phase A, die sich auf das grundlegende Verständnis von Kohlebränden, sowie der Voraussetzung und des prinzipiellen Ablaufs der physikalischchemischen Brandprozesse konzentriert haben, erfolgte in Phase B eine Fokussierung auf Methoden zur Vermeidung von Kohlebränden, sowie der Löschung und Überwachung von Kohlebrandzonen, um einen Beitrag zur Verminderung von C02-Emissionen und zum Erhalt der nutzbaren Energieressourcen leisten zu können. Diese Arbeiten erfolgten insbesondere mit Bezug zu den „Clean Development Mechanisms“ (CDM), die im Rahmen des Kyoto-Protokolls entwickelt worden sind.
Eine Zertifizierung von Löschaktivitäten im Rahmen des Kyoto-Protokolls setzt dabei eine nachvollziehbare Ermittlung der kohlebrandbezogenen C02-Emissionen und eine belastbare Abschätzung der durch die Löschung verringerten Emissionsmengen voraus. Wesentliche Arbeiten konzentrierten sich auf die Entwicklung von Verfahren, die eine solche Abschätzung gewährleisten können. Dazu wurden unterschiedliche Ansätze entwickelt und anhand der erhobenen Felddaten überprüft. Die untersuchten Ansätze konzentrierten sich dabei auf Verfahren, die eine Ermittlung des vorhandenen Kohlevolumens, die Erfassung der emittierten Gase und die durch die Kohlebrände verursachten Temperaturanomalien an der Tagesoberfläche ermöglichen. Die direkten Arbeiten zum Thema CDM wurden dabei in einem Arbeitspaket unter Federführung der BGR gebündelt.
Die deutsche Initiative zur Erforschung der Kohlenbrände in der V.R. China leistete zweifelsfrei signifikante Beiträge zu den oben genannten Zielen. Durch die inventiven Ansätze im Bereich der Brandbewältigung konnte darüber hinaus auch in Teilen die ökonomischen Chancen für ein Engagement deutscher Unternehmen aufgezeigt werden.