Arbeitszeitbedarf in der Mutterkuhhaltung unter kleinstrukturierten Produktionsbedingungen

There was a lack of up-to-date statistics on the working time requirements in suckler cattle farming under Swiss production conditions. A combination of final and causal methods for recording working time was used to determine working-time input and working-time requirements, to survey influence variables and draw up working-time models using a model calculation system. The total working time spent on suckler cattle farming varied between 28 and 120 hours per cow per year, with an average of 66 hours per cow per year. Over half of this time was spent on routine work, 20 % on management work, 19 % on other non-daily work and 3 % on direct marketing, animal care and animal handling, respectively. The larger the herd size, the lower the time spent on winter routine work. Feeding systems such as ad-libitum feeding in racks or self-feeding at the bunker silo have a positive effect on working time requirements. Besides herd size, factors such as the housing system, process engineering, type of production, available working time, intensity of production and farm management also have a significant effect on working time

Signatures of electronic polarons in La1−x_{1-x}Sr1+x_{1+x}MnO4_4 observed by electron energy-loss spectroscopy

The dielectric properties of La$_{1-x}$Sr$_{1+x}$MnO$_4$ single crystals with x = 0, 0.125, 0.25, and 0.5 were studied by means of electron energy-loss spectroscopy as a function of temperature and momentum transfer. A clear signature of the doped holes is observed around 1.65 eV energy loss, where spectral weight emerges with increasing x. For all $x \neq 0$, this doping-induced excitation can propagate within the ab-plane, as revealed by a clear upward dispersion of the corresponding loss peak with increasing momentum transfer. The hole-induced excitation also shifts to higher energies with the onset of magnetic correlations for x = 0.5, implying a strong coupling of charge and spin dynamics. We conclude that (i) the loss feature at 1.65 eV is a signature of electronic polarons, which are created around doped holes, and that (ii) this low-energy excitation involves the charge transfer between manganese and oxygen. The finite dispersion of these excitations further indicates significant polaron-polaron interactions.Comment: 7 pages, 4 figure

Shallow impurity band in ZrNiSn

ZrNiSn and related half Heusler compounds are candidate materials for efficient thermoelectric energy conversion with a reported thermoelectric figure-of-merit of n-type ZrNiSn exceeding unity. Progress on p-type materials has been more limited, which has been attributed to the presence of an impurity band, possibly related to the presence of Ni interstitials in nominally vacant 4d position. The specific energetic position of this band, however, has not been resolved. Here, we report results of a concerted theory-experiment investigation for a nominally undoped ZrNiSn, based on measurements of electrical resistivity, Hall coefficient, Seebeck coefficient and Nernst coefficient, measured in a temperature range from 80 to 420 K. The results are analyzed with a semi-analytical model combining a density functional theory (DFT) description for ideal ZrNiSn, with a simple analytical correction for the impurity band. The model provides a good quantitative agreement with experiment, describing all salient features in the full temperature span for the Hall, conductivity, and Seebeck measurements, while also reproducing key trends in the Nernst results. This comparison pinpoints the impurity band edge to 40 meV below the conduction band edge, which agrees well with a separate DFT study of a supercell containing Ni interstitials. Moreover, we corroborate our result with a separate study of ZrNiSn0.9Pb0.1 sample showing similar agreement with an impurity band edge shifted to 32 meV below the conduction band

Fabrication of a Silicide Thermoelectric Module Employing Fractional Factorial Design Principles

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NFDI4Culture - Consortium for research data on material and immaterial cultural heritage

Digital data on tangible and intangible cultural assets is an essential part of daily life, communication and experience. It has a lasting influence on the perception of cultural identity as well as on the interactions between research, the cultural economy and society. Throughout the last three decades, many cultural heritage institutions have contributed a wealth of digital representations of cultural assets (2D digital reproductions of paintings, sheet music, 3D digital models of sculptures, monuments, rooms, buildings), audio-visual data (music, film, stage performances), and procedural research data such as encoding and annotation formats. The long-term preservation and FAIR availability of research data from the cultural heritage domain is fundamentally important, not only for future academic success in the humanities but also for the cultural identity of individuals and society as a whole. Up to now, no coordinated effort for professional research data management on a national level exists in Germany. NFDI4Culture aims to fill this gap and create a usercentered, research-driven infrastructure that will cover a broad range of research domains from musicology, art history and architecture to performance, theatre, film, and media studies. The research landscape addressed by the consortium is characterized by strong institutional differentiation. Research units in the consortium's community of interest comprise university institutes, art colleges, academies, galleries, libraries, archives and museums. This diverse landscape is also characterized by an abundance of research objects, methodologies and a great potential for data-driven research. In a unique effort carried out by the applicant and co-applicants of this proposal and ten academic societies, this community is interconnected for the first time through a federated approach that is ideally suited to the needs of the participating researchers. To promote collaboration within the NFDI, to share knowledge and technology and to provide extensive support for its users have been the guiding principles of the consortium from the beginning and will be at the heart of all workflows and decision-making processes. Thanks to these principles, NFDI4Culture has gathered strong support ranging from individual researchers to highlevel cultural heritage organizations such as the UNESCO, the International Council of Museums, the Open Knowledge Foundation and Wikimedia. On this basis, NFDI4Culture will take innovative measures that promote a cultural change towards a more reflective and sustainable handling of research data and at the same time boost qualification and professionalization in data-driven research in the domain of cultural heritage. This will create a long-lasting impact on science, cultural economy and society as a whole

On the Oxygen Nonstoichiometry in Thermoelectric Oxides

The interest in thermoelectric oxides as candidate materials for high temperature waste heat recovery has generated vital scientific activity during the last years. However, while it is well established in several other fields of materials science that the electronic structure of oxides at high temperatures can be significantly modified by the formation of oxygen vacancies, the precise control of the sample and its surrounding atmosphere is rather seldomly seen in scientific publications on high temperature thermoelectric oxides. Therefore, during this thesis, I have investigated the influence of the oxygen content on the properties of two of the most prominent thermoelectric oxides. A variation of the oxygen content of a material at high temperatures can be achieved by a variation of the surrounding atmosphere and the subsequent in- and out-diffusion of oxygen ions until the new thermodynamic equilibrium state is reached. Oxygen vacancies can usually be described as effectively charged point defects and the precise control of their concentration provides a means to change the charge carrier concentration of a material in situ. Therefore, one goal of this thesis is to establish that the high temperature thermoelectric characterisation of oxides should preferably be done under controlled atmospheric conditions. In fact, part of the scatter observed in published results on nominally identical samples can be explained by (unintentionally) different oxygen content, due to different measurement atmospheres or sample kinetics. Moreover, the results from this thesis aim to contribute to the fundamental understanding of the charge transport processes in the studied and related materials. The thesis comprises the design and characterisation of an appropriate system to measure the electrical transport properties of the materials under investigation (Manuscript 3). Manuscript 1 and 4 study one of the most prominent thermoelectric oxides: Misfit calcium cobalt oxide (Ca2CoO3-δ)q(CoO2) (CCO), which shows one of the best reproducible p-type thermoelectric performances among all oxides. In Manuscript 1, we established a defect chemical model of this material. Due to its misfit structure, it is inherently mixed-valent, so that a modified defect notation was chosen. The dependency of both electrical conductivity and Seebeck coefficient on the oxygen content was measured in a wide range of temperature and oxygen partial pressure. It was concluded that – at high temperatures – charge carriers should be described as itinerant in this material. We further showed that the often used Heikes formula cannot be used for a quantitative analysis of the Seebeck coeffcient in CCO. Instead, we suggested a modified Mott formula with a significant contribution from the energy dependent mobility to describe the Seebeck coefficient in CCO. In Manuscript 4, a combined experimental and theoretical study of the oxygen nonstoichiometry in CCO is presented. Based on DFT-calculations and experimental Raman-spectroscopy, it is shown that oxygen is preferentially removed from an atomic position within the central layer of the Ca2CoO3-subsystem. The computational results further indicated that the electronic properties are sensitive to small variations in the crystal structure. The thermodynamics of oxidation were investigated by three different techniques (TG, TG-DSC, and DFT) and differences were discussed. In Manuscript 2, the high temperature charge transport in CaMnO3-δ (CMO) was investigated. CMO is – when doped with small amounts of niobium – among the most promising n-type oxides with a figure of merit reaching 0.3 at high temperatures. When forming oxygen vacancies – thereby increasing the electron concentration of the material – we observed an unusual simultaneous decrease of both conductivity and the absolute value of the Seebeck coefficient. These findings were analysed as an indication of strongly interacting small polarons as the charge carrier in this material. We generalised this result to develop a simple model for the powerfactor and concluded that mutual Coulomb repulsion limits the thermoelectric performance of these materials

Hall effect measurements on thermoelectric Ca3Co4O9: On how to determine the charge carrier concentration in strongly correlated misfit cobaltites

The Hall coefficient RH and electrical conductivity of misfit calcium cobalt oxide (Ca2CoO3−δ)q(CoO2) (CCO) were measured at room temperature for different oxygen vacancy concentrations δ. Based on these and numerous previous results, it is shown that the charge carrier concentrations n obtained by the classical formula RH = 1/ne are between 3 and 6 × 1020 cm−3 and thereby much lower than those derived by other experimental techniques and fail to explain the observed electric properties of CCO. We show that the experimental results are well described using an earlier proposed t–J-model for strongly correlated electrons on a triangular lattice. The hopping parameter t for CCO was found to be ≈ −20 K and the charge carrier concentration of fully oxidized CCO to be 5.7 × 1021 cm−3 (0.41 hole type carriers per formula unit), in agreement with other experimental techniques. This research was originally published in the Journal of Applied Physics. © AIP Publishin

Centimeter-Sized Monolayer CVD Graphene with High Power Factor for Scalable Thermoelectric Applications

Among the many extraordinary qualities of graphene, its thermoelectric properties have attracted significant interest, for example, in active cooling applications. Here, we report on the thermoelectric transport properties of centimeter-sized monolayer CVD graphene, electrostatically controlled by a high-capacity ionic gel. The power factor reaches 7 and 5.4 mW m–1 K–2 for hole and electron conduction, respectively, similar to earlier reports obtained for microdevices despite our devices being over 2 orders of magnitude larger. On the basis of these results, we propose nonvolatile ferroelectric polarization as a scalable technology for graphene-based thermoelectric applications.publishedVersio