3,129 research outputs found
Software Engineering Laboratory (SEL) database organization and user's guide
The organization of the Software Engineering Laboratory (SEL) database is presented. Included are definitions and detailed descriptions of the database tables and views, the SEL data, and system support data. The mapping from the SEL and system support data to the base tables is described. In addition, techniques for accessing the database, through the Database Access Manager for the SEL (DAMSEL) system and via the ORACLE structured query language (SQL), are discussed
Eukaryotic translation elongation factor 1A (eEF1A) domain I from S. cerevisiae is required but not sufficient for inter-species complementation
Ethanolamine phosphoglycerol (EPG) is a protein modification attached exclusively to eukaryotic elongation factor 1A (eEF1A). In mammals and plants, EPG is linked to conserved glutamate residues located in eEF1A domains II and III, whereas in the unicellular eukaryote Trypanosoma brucei, only domain III is modified by a single EPG. A biosynthetic precursor of EPG and structural requirements for EPG attachment to T. brucei eEF1A have been reported, but nothing is known about the EPG modifying enzyme(s). By expressing human eEF1A in T. brucei, we now show that EPG attachment to eEF1A is evolutionarily conserved between T. brucei and Homo sapiens. In contrast, S. cerevisiae eEF1A, which has been shown to lack EPG is not modified in T. brucei. Furthermore, we show that eEF1A cannot functionally complement across species when using T. brucei and S. cerevisiae as model organisms. However, functional complementation in yeast can be obtained using eEF1A chimera containing domains II or III from other species. In contrast, yeast domain I is strictly required for functional complementation in S. cerevisia
Investigation of a high angle grain boundary in Fe2.4wt.%Si BCC micropillars
Iron-silicon sheet steel is the most widely used material for the iron cores of electrical machines like generators, motors or transformers. Although already ubiquitous, the demand will nevertheless rise in the future since electro-mobility is spreading rapidly. For this reason, even small improvements of efficiency have a huge energy saving potential. Currently, hysteresis losses are one of the main limiting factors for efficiency, resulting from the movement of domain walls, which may be pinned by dislocations. Even though electrical sheet steel is generally used in a fully recrystallized state, it is the final stages of production involving cutting that introduce large plastic strains, and hence high local dislocation densities. These have been shown to cause significant loss in performance.
The aim of this work is to understand the evolution of deformation structures on a fundamental basis taking grain boundaries, size effects and different strain-rates into account. To this end, single- and bi-crystalline-micropillars of 1, 2 und 4 µm in diameter were investigated. 158 micropillars were deformed in order to provide a statistically-relevant dataset. In addition, macroscopic single- and bi-crystal-samples with a diameter of 2.5 mm were deformed as a reference for the size effect. The considered grain boundary has an angle of about 50° and a very high geometrical transmission factor (m’=0.89). Regarding the strain-rate-sensitivity three different strain rates were used for the deformation of the micro-/macroscopic single- and bi-crystals, with strain rate jump tests additionally conducted for the single-crystals. To visualize the deformation structure, selected micropillars were lifted out of the sample, thinned to the middle and analyzed utilizing EBSD.
For most micropillars a clear slip system could be determined. Regarding one orientation the active slip system changed from the single- to the bi-crystal, likely because the newly-activated slip system was better aligned relative to the slip system of the other half-crystal. The bi-crystal-micropillars showed a higher resolved shear stress despite direct slip transmission across the grain boundary. Furthermore, a pronounced strain-rate sensitivity and size effect was found
A New Approach to Measure Fundamental Microstructural Influences on the Magnetic Properties of Electrical Steel using a Miniaturized Single Sheet Tester
Magnetic properties of electrical steel are usually measured on Single Sheet
Testers, Epstein frames or ring cores. Due to the geometric dimensions and
measurement principles of these standardized setups, the fundamental
microstructural influences on the magnetic behavior, e.g., deformation
structures, crystal orientation or grain boundaries, are difficult to separate
and quantify. In this paper, a miniaturized Single Sheet Tester is presented
that allows the characterization of industrial steel sheets as well as from in
size limited single, bi- and oligocrystals starting from samples with
dimensions of 10x22 mm. Thereby, the measurement of global magnetic properties
is coupled with microstructural analysis methods to allow the investigation of
micro scale magnetic effects. An effect of grain orientation, grain boundaries
and deformation structures has already been identified with the presented
experimental setup. In addition, a correction function is introduced to allow
quantitative comparisons between differently sized Single Sheet Testers. This
approach is not limited to the presented Single Sheet Tester geometry, but
applicable for the comparison of results of differently sized Single Sheet
Testers. The results of the miniaturized Single Sheet Tester were validated on
five industrial electrical steel grades. Furthermore, first results of
differently oriented single crystals as well as measurements on grain-oriented
electrical steel are shown to prove the additional value of the miniaturized
Single Sheet Tester geometry
Designing educational futures: imagine a collaborative Bloom
This commentary is a working out loud of what a liberatory education might entail that builds on partnership and co-creation. Proposed is the addition of collaboration as a central element to education, to break individuality and hierarchy - for collective, socially just action. The perquisites for this is openness - and the abandonment of the neoliberal competitive approach to education as well as the conscious development and use of Open EdTech for connection. Why? Because we need the collective intelligence to address the challenges of the twenty-first century and beyond
Deformation of micrometer and mm-sized Fe2.4wt.%Si single- and bi-crystals with a high angle grain boundary at room temperature
Plasticity in body-centred cubic (BCC) metals, including dislocation
interactions at grain boundaries, is much less understood than in face-centred
cubic (FCC) metals. At low temperatures additional resistance to dislocation
motion due to the Peierls barrier becomes important, which increases the
complexity of plasticity. Iron-silicon steel is an interesting, model BCC
material since the evolution of the dislocation structure in
specifically-oriented grains and at particular grain boundaries have
far-reaching effects not only on the deformation behaviour but also on the
magnetic properties, which are important in its final application as electrical
steel. In this study, two different orientations of micropillars (1, 2, 4
microns in diameter) and macropillars (2500 microns) and their corresponding bi
crystals are analysed after compression experiments with respect to the effect
of size on strength and dislocation structures. Using different experimental
methods, such as slip trace analysis, plane tilt analysis and cross-sectional
EBSD, we show that direct slip transmission occurs, and different slip systems
are active in the bi-crystals compared to their single-crystal counterparts.
However, in spite of direct transmission and a very high transmission factor,
dislocation pile-up at the grain boundary is also observed at early stages of
deformation. Moreover, an effect of size scaling with the pillar size in single
crystals and the grain size in bi-crystals is found, which is consistent with
investigations elsewhere in FCC metals
Gene expression of tendon markers in mesenchymal stromal cells derived from different sources
Background: Multipotent mesenchymal stromal cells (MSC) can be recovered from a variety of tissues in the body. Yet, their functional properties were shown to vary depending on tissue origin. While MSC have emerged as a favoured cell type for tendon regenerative therapies, very little is known about the influence of the MSC source on
their properties relevant to tendon regeneration. The aim of this study was to assess and compare the expression of tendon extracellular matrix proteins and tendon differentiation markers in MSC derived from different sources as well as in native tendon tissue. MSC isolated from equine bone marrow, adipose tissue, umbilical cord tissue, umbilical cord blood and tendon tissue were characterized and then subjected to mRNA analysis by real-time polymerase chain reaction. Results: MSC derived from adipose tissue displayed the highest expression of collagen 1A2, collagen 3A1 and decorin compared to MSC from all other sources and native tendon tissue (p < 0.01). Tenascin-C and scleraxis
expressions were highest in MSC derived from cord blood compared to MSC derived from other sources, though both tenascin-C and scleraxis were expressed at significantly lower levels in all MSC compared to native tendon tissue (p < 0.01). Conclusions: These findings demonstrate that the MSC source impacts the cell properties relevant to tendon regeneration. Adipose derived MSC might be superior regarding their potential to positively influence tendon matrix reorganization
St. Petri Cathedral Schleswig: non-destructive geophysical damage analysis of medieval plaster
Non-destructive geophysical methods were applied to detect moisture at the St. Petri Cathedral in Schleswig. One of them is thermography, which allows to distinguish between intact and defective medieval plaster. Additionally, thesuccess of a restoration can be determined by ultrasonic surface measurements
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Editorial: Wie gestalten wir die Zukunft mit Open Access und Open Educational Resources?
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Thermal activation of plasticity in BCC materials investigated by cryo-micropillar compression
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