Wissenschaftliche Artikel der BAM
Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (1778)
- Beitrag zu einem Tagungsband (37)
- Forschungsbericht (1)
Sprache
- Englisch (1801)
- Deutsch (11)
- Mehrsprachig (3)
- Portugiesisch (1)
Referierte Publikation
- ja (1816) (entfernen)
Schlagworte
- Additive manufacturing (54)
- Fluorescence (54)
- SAXS (43)
- Nanoparticles (40)
- Quantum yield (36)
- MALDI-TOF MS (34)
- Concrete (32)
- Corrosion (28)
- Mechanochemistry (28)
- Polylactide (26)
Organisationseinheit der BAM
- 6 Materialchemie (399)
- 1 Analytische Chemie; Referenzmaterialien (331)
- 8 Zerstörungsfreie Prüfung (266)
- 5 Werkstofftechnik (173)
- 4 Material und Umwelt (168)
- 7 Bauwerkssicherheit (166)
- 6.3 Strukturanalytik (155)
- 9 Komponentensicherheit (152)
- 8.5 Röntgenbildgebung (103)
- 6.1 Oberflächen- und Dünnschichtanalyse (93)
- 1.2 Biophotonik (73)
- 5.1 Mikrostruktur Design und Degradation (67)
- 6.6 Physik und chemische Analytik der Polymere (62)
- 1.1 Anorganische Spurenanalytik (61)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (59)
- 6.2 Material- und Oberflächentechnologien (56)
- 9.4 Integrität von Schweißverbindungen (56)
- 1.7 Organische Spuren- und Lebensmittelanalytik (54)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (53)
- 4.1 Biologische Materialschädigung und Referenzorganismen (52)
- 9.3 Schweißtechnische Fertigungsverfahren (52)
- 6.5 Synthese und Streuverfahren nanostrukturierter Materialien (51)
- 6.0 Abteilungsleitung und andere (49)
- 1.4 Prozessanalytik (48)
- 3 Gefahrgutumschließungen; Energiespeicher (45)
- 1.5 Proteinanalytik (44)
- 7.4 Baustofftechnologie (43)
- 5.2 Metallische Hochtemperaturwerkstoffe (41)
- 1.8 Umweltanalytik (40)
- 4.3 Schadstofftransfer und Umwelttechnologien (38)
- 8.3 Thermografische Verfahren (36)
- 8.6 Faseroptische Sensorik (36)
- 5.4 Multimateriale Fertigungsprozesse (32)
- 1.9 Chemische und optische Sensorik (31)
- 4.0 Abteilungsleitung und andere (27)
- 9.0 Abteilungsleitung und andere (27)
- 9.2 Versuchsanlagen und Prüftechnik (27)
- 4.2 Material-Mikrobiom Wechselwirkungen (24)
- 5.5 Materialmodellierung (24)
- 8.0 Abteilungsleitung und andere (24)
- 4.4 Thermochemische Reststoffbehandlung und Wertstoffrückgewinnung (23)
- 8.4 Akustische und elektromagnetische Verfahren (23)
- S Qualitätsinfrastruktur (22)
- VP Vizepräsident (21)
- VP.1 eScience (21)
- 2 Prozess- und Anlagensicherheit (20)
- 7.2 Ingenieurbau (20)
- 9.6 Additive Fertigung metallischer Komponenten (19)
- 2.1 Sicherheit von Energieträgern (18)
- 5.6 Glas (18)
- 7.6 Korrosion und Korrosionsschutz (18)
- 1.3 Instrumentelle Analytik (17)
- 3.1 Sicherheit von Gefahrgutverpackungen und Batterien (17)
- 7.1 Baustoffe (16)
- 5.0 Abteilungsleitung und andere (15)
- 5.3 Polymere Verbundwerkstoffe (15)
- 1.6 Anorganische Referenzmaterialien (14)
- 1.0 Abteilungsleitung und andere (13)
- 4.5 Kunst- und Kulturgutanalyse (13)
- S.2 Digitalisierung der Qualitätsinfrastruktur (13)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (12)
- 9.5 Tribologie und Verschleißschutz (12)
- P Präsident (10)
- P.0 Präsident und andere (10)
- 6.7 Materialsynthese und Design (9)
- 3.4 Sicherheit von Lagerbehältern (8)
- 7.0 Abteilungsleitung und andere (8)
- 7.3 Brandingenieurwesen (8)
- 7.7 Modellierung und Simulation (8)
- 3.5 Sicherheit von Gasspeichern (7)
- 6.4 Materialinformatik (7)
- 3.6 Elektrochemische Energiematerialien (6)
- S.3 Ökodesign und Energieverbrauchskennzeichnung (6)
- 3.2 Gefahrguttanks und Unfallmechanik (5)
- S.1 Qualität im Prüfwesen (4)
- 3.0 Abteilungsleitung und andere (3)
- 4.6 Molekulare und angewandte Entomologie (3)
- 2.2 Prozesssimulation (1)
- 2.5 Konformitätsbewertung Explosivstoffe/Pyrotechnik (1)
- PST Präsidiale Stabsstelle (1)
Paper des Monats
- ja (71)
Ground penetrating radar (GPR) was used to characterize the frequency-dependent dielectric relaxation phenomena in ordinary Portland cement (OPC) hydration in concrete changing from fresh to hardened state. The study was experimented by measuring the changes of GPR A-scan waveforms over a period of 90 days, and processed the waveforms with short-time Fourier transform (STFT) in joint time-frequency analysis (JTFA) domain rather than a conventional time or frequency domain alone. The signals of the direct wave traveled at the concrete surface and the reflected wave from an embedded steel bar were transformed with STFT, in which the changes of peak frequency over ages were tracked. The peak frequencies were found to increase with ages and the patterns were found to match closely with primarily the well-known OPC hydration process and secondarily, the evaporation effect. The close match is contributed to the simultaneous effects converting free to bound water over time, on both conventional OPC hydration and dielectric relaxation mechanisms.
Digital radiography in the inspection of welded pipes to be installed under deep water offshore gas and oil pipelines, like a presalt in Brazil, in the paper has been investigated. The aim is to use digital radiography for nondestructive testing of welds as it is already in use in the medical, aerospace, security, automotive, and petrochemical sectors. Among the current options, the DDA (Digital Detector Array) is considered as one of the best solutions to replace industrial films, as well as to increase the sensitivity to reduce the inspection cycle time. This paper shows the results of this new technique, comparing it to radiography with industrial films systems. In this paper, 20 test specimens of longitudinal welded pipe joints, specially prepared with artificial defects like cracks, lack of fusion, lack of penetration, and porosities and slag inclusions with varying dimensions and in 06 different base metal wall thicknesses, were tested and a comparison of the techniques was made. These experiments verified the purposed rules for parameter definitions and selections to control the required digital radiographic image quality as described in the draft international standard ISO/DIS 10893-7. This draft is first standard establishing the parameters for digital radiography on weld seam of welded steel pipes for pressure purposes to be used on gas and oil pipelines.
Phosphorus-based flame retardancy mechanisms - Old hat or a starting point for future development?
(2010)
Different kinds of additive and reactive flame retardants containing phosphorus are increasingly successful as halogen-free alternatives for various polymeric materials and applications. Phosphorus can act in the condensed phase by enhancing charring, yielding intumescence, or through inorganic glass formation; and in the gas phase through flame inhibition. Occurrence and efficiency depend, not only on the flame retardant itself, but also on its interaction with pyrolysing polymeric material and additives. Flame retardancy is sensitive to modification of the flame retardant, the use of synergists/adjuvants, and changes to the polymeric material. A detailed understanding facilitates the launch of tailored and targeted development.
The class Dothideomycetes (along with Eurotiomycetes) includes numerous rock-inhabiting fungi (RIF), a group of ascomycetes that tolerates surprisingly well harsh conditions prevailing on rock surfaces. Despite their convergent morphology and physiology, RIF are phylogenetically highly diverse in Dothideomycetes. However, the positions of main groups of RIF in this class remain unclear due to the lack of a strong phylogenetic framework. Moreover, connections between rock-dwelling habit and other lifestyles found in Dothideomycetes such as plant pathogens, saprobes and lichen-forming fungi are still unexplored. Based on multigene phylogenetic analyses, we report that RIF belong to Capnodiales (particularly to the family Teratosphaeriaceae s.l.), Dothideales, Pleosporales, and Myriangiales, as well as some uncharacterised groups with affinities to Dothideomycetes. Moreover, one lineage consisting exclusively of RIF proved to be closely related to Arthoniomycetes, the sister class of Dothideomycetes. The broad phylogenetic amplitude of RIF in Dothideomycetes suggests that total species richness in this class remains underestimated. Composition of some RIF-rich lineages suggests that rock surfaces are reservoirs for plant-associated fungi or saprobes, although other data also agree with rocks as a primary substrate for ancient fungal lineages. According to the current sampling, long distance dispersal seems to be common for RIF. Dothideomycetes lineages comprising lichens also include RIF, suggesting a possible link between rock-dwelling habit and lichenisation.
Die Analytik von Phthalaten (DMP bis DEHP) in der Luft ist mit thermischer Desorption unter Verwendung von Quarzwolle als Adsorbens erfolgreich realisierbar. Dies wurde durch eine Methodenvalidierung bestätigt. Es wurden sowohl Messungen im Innenraum als auch in Emissionskammern vorgenommen. In den Emissionskammermessungen wurden mögliche Senkeneffekte der Kammeroberfläche (Glas) untersucht. Unter Zuhilfenahme der idealen Abklingkurve wird bestätigt, dass diese Oberfläche eine Senke darstellt.
Cold cracking resistance is a relevant evaluation criterion for welded joints and affected by residual stresses which result from the welding procedure. Compressive residual stresses can thereby have a positive influence on preventing cracking. A unique possibility of generating compressive residual stresses already during the welding procedure is offered by the so-called Low Transformation Temperature (LTT) filler wires. Compared to conventional wires, these materials show decreased phase transformation temperatures which can work against the cooling-specific contraction. In consequence, distinct compressive residual stresses can be observed within the weld and adjacent areas. The strength of these fillers makes them potentially applicable to high-strength steel welding. Investigations were carried out to determine the phase transformation behaviour of different LTT-filler materials. Transformation temperatures were identified using Single Sensor Differential Thermal Analysis (SS-DTA). Additionally Synchrotron radiation was used to measure the transformation kinetics of all involved crystalline phases during heating and cooling of a simulated weld thermal cycle.
For the safety and cost efficiency of welded high-strength steel structures, precise knowledge of the level and distribution of welding- and cooling-specific stresses and residual stresses is essential, since they exert a decisive influence on strength, crack resistance, and finally on the bearable service load. This paper presents innovative filler materials, of which the phase transformation temperature was deliberately adjusted via the chemical composition. The transformation behaviour of these martensitic Low Transformation Temperature (LTT-) filler materials shows direct effects on the local residual stresses in the weld and the HAZ. These effects can purposefully be exploited to counteract the thermally induced shrinkage of the material and to produce significant compressive residual stresses in the weld. Comparative welding experiments were carried out on 690 MPa high-strength base materials using various LTT-filler materials. High energy synchrotron radiation was used for residual stress measurement. Particularly the use of high energy synchrotron radiation makes it possible to detect the residual stress condition fast without destruction of material. Thereby, residual stress depth gradients can be determined simultaneously without removing material. In steel, gradients of up to 150 µm can be resolved in such a way. Furthermore, the application of high energy radiation permits determination of residual stresses of any available residual austenite contents. Results show significant dependence of transformation temperatures on the resulting residual stress level and distribution.
Aflatoxins, a group of structurally related mycotoxins, are well known for their
toxic and carcinogenic effects in humans and animals. Aflatoxin derivatives and protein
conjugates are needed for diverse analytical applications. This work describes a reliable
and fast synthesis of novel aflatoxin derivatives, purification by preparative HPLC and
characterisation by ESI-MS and one- and two-dimensional NMR. Novel aflatoxin bovine
serum albumin conjugates were prepared and characterised by UV absorption and
MALDI-MS. These aflatoxin protein conjugates are potentially interesting as immunogens
for the generation of aflatoxin selective antibodies with novel specificities.
To date silica nanoparticles (SNPs) play an important role in modern technology and nanomedicine. SNPs are present in various materials (tyres, electrical and thermal insulation material, photovoltaic facilities). They are also used in products that are directly exposed to humans such as cosmetics or toothpaste. For that reason it is of great concern to evaluate the possible hazards of these engineered particles for human health. Attention should primarily be focussed on SNP effects on biological barriers. Accidentally released SNP could, for example, encounter the alveolar-capillary barrier by inhalation. In this study we examined the inflammatory and cytotoxic responses of monodisperse amorphous silica nanoparticles (aSNPs) of 30 nm in size on an in vitro coculture model mimicking the alveolar-capillary barrier and compared these to conventional monocultures.
Methods
Thus, the epithelial cell line, H441, and the endothelial cell line, ISO-HAS-1, were used in monoculture and in coculture on opposite sides of a filter membrane. Cytotoxicity was evaluated by the MTS assay, detection of membrane integrity (LDH release), and TER (Transepithelial Electrical Resistance) measurement. Additionally, parameters of inflammation (sICAM-1, IL-6 and IL-8 release) and apoptosis markers were investigated.
Results
Regarding toxic effects (viability, membrane integrity, TER) the coculture model was less sensitive to apical aSNP exposure than the conventional monocultures of the appropriate cells. On the other hand, the in vitro coculture model responded with the release of inflammatory markers in a much more sensitive fashion than the conventional monoculture. At concentrations that were 10-100fold less than the toxic concentrations the apically exposed coculture showed a release of IL-6 and IL-8 to the basolateral side. This may mimic the early inflammatory events that take place in the pulmonary alveoli after aSNP inhalation. Furthermore, a number of apoptosis markers belonging to the intrinsic pathway were upregulated in the coculture following aSNP treatment. Analysis of the individual markers indicated that the cells suffered from DNA damage, hypoxia and ER-stress.
Conclusion
We present evidence that our in vitro coculture model of the alveolar-capillary barrier is clearly advantageous compared to conventional monocultures in evaluating the extent of damage caused by hazardous material encountering the principle biological barrier in the lower respiratory tract.
High welding residual stresses can cause service life reducing consequences. Even though many processes have been developed to reduce these stresses, they are only applicable for wider welds and simple component geometries or are cost-intensive, respectively. The presented method uses a defocused beam after welding for heating the material regions on both sides of the weld. In this way, the welding stresses are decreased without contacting the surfaces using the available equipment. Different process parameters could be used depending on the component geometry and the laser power. The mechanism and the influence of the process parameters were investigated by FEM-simulation and experiments on S355J2+N steel and showed a stress reduction of about 73%.
Carbon capture & storage (CCS) is one of the most promising technologies for greenhouse gas (GHG) management. However, an unsolved issue of CCS is the development of appropriate long-term monitoring systems for leak detection of the stored CO2. To complement already existing monitoring infrastructure for CO2 storage areas, and to increase the granularity of gas concentration measurements, a quickly deployable, mobile measurement device is needed. In this paper, we present an autonomous gas-sensitive micro-drone, which can be used to monitor GHG emissions, more specifically, CO2. Two different measurement strategies are proposed to address this task. First, the use of predefined sensing trajectories is evaluated for the task of gas distribution mapping using the micro-drone. Alternatively, we present an adaptive strategy, which suggests sampling points based on an artificial potential field (APF). The results of real-world experiments demonstrate the feasibility of using gas-sensitive micro-drones for GHG monitoring missions. Thus, we suggest a multi-layered surveillance system for CO2 storage areas.
Separation of CO2. Microporous polyurethane networks were prepared based on a renewable resource. Betulin, extracted from birch bark, is used as a structure-directing diol monomer in A3-B2 monomers. The resulting microporous networks show very promising CO2/N2 selectivities. The state of adsorbed CO2 is analyzed by in situ NMR spectroscopy, and pure physisorption is proven. The preparation of monolithic materials is demonstrated as well.
Dendrimers of various generations were synthesized by the divergent method. Starting from various amine cores (G0a, G0b, G0c) the generations were built by reaction of the amine with acrylnitrile followed by hydrogenation with DIBAL-H. Treatment with salicylaldehyde creates a fivefold coordination sphere for iron in the molecular periphery. The resulting multinuclear coordination compounds are investigated by Mossbauer spectroscopy.
Crystals of the title compound, C18H26O2, were grown from ethyl acetate. Due to the racemic precursor, the title compound is also obtained as a racemate. Disorder was observed during structure refinement, originating from two possible half-chair conformations of the non-aromatic ring. The disorder was refined by introducing split positions in the cyclo-hexane ring regarding the two possible R and S-enantiomers at the chiral CH group [ratio 0.744 (3):0.256 (3)]. The crystal structure features pairs of inversion-related molecules connected by pairs of non-classical C–H···O hydrogen bonds.
So near and yet so far: harmonic radar reveals reduced homing ability of Nosema infected honeybees
(2014)
Pathogens may gain a fitness advantage through manipulation of the behaviour of their hosts. Likewise, host behavioural changes can be a defence mechanism, counteracting the impact of pathogens on host fitness. We apply harmonic radar technology to characterize the impact of an emerging pathogen - Nosema ceranae (Microsporidia) - on honeybee (Apis mellifera) flight and orientation performance in the field. Honeybees are the most important commercial pollinators. Emerging diseases have been proposed to play a prominent role in colony decline, partly through sub-lethal behavioural manipulation of their hosts. We found that homing success was significantly reduced in diseased (65.8%) versus healthy foragers (92.5%). Although lost bees had significantly reduced continuous flight times and prolonged resting times, other flight characteristics and navigational abilities showed no significant difference between infected and non-infected bees. Our results suggest that infected bees express normal flight characteristics but are constrained in their homing ability, potentially compromising the colony by reducing its resource inputs, but also counteracting the intra-colony spread of infection. We provide the first high-resolution analysis of sub-lethal effects of an emerging disease on insect flight behaviour. The potential causes and the implications for both host and parasite are discussed.