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Aufsatz
Ferrocene-Based N-Heterocyclic Plumbylenes [Fe{(η⁵- C₅H₄)NSiMe₂R}₂Pb:]: Influence of the Steric Demand of the NSubstituents on Their Dimerization via C-H Activation with Pbᴵᴵ
(2023-05-12)
Ferrocene-based N-heterocyclic plumbylenes fc[(NSiMe₂R)₂Pb:] (1; fc=1,1’-ferrocenylene) are easily accessible by transamination from [(Me₃Si)₂N]₂Pb and the corresponding 1,1’-diaminoferrocene derivatives fc(NHSiMe₂R)₂. They may form unconventional dimers 2 by a process, which causes the cleavage of a cyclopentadienyl C−H bond and the formation of a Pb−C and an N−H bond. The monomer-dimer equilibrium (2 1⇆2) has been addressed experimentally and computationally. It critically depends on the steric demand of the ...
Aufsatz
Observation of a Long-lived Electronic Coherence Modulated by Vibrational Dynamics in Molecular Nd³+- Complexes at Room Temperature
(2023-03-23)
Temporally delayed, phase-locked coherent pairs of near IR femtosecond laser pulses were employed to study electronic coherences in molecular Nd³+-complexes at room temperature. Dissolved and solid complexes were studied under a confocal microscope set-up with fluorescence detection. The observed electronic coherence on a few hundred femtoseconds time scale is modulated by additional coherent wave packet dynamics, which we attribute mainly to be vibrational in nature. In future, the complexes may serve as prototypes ...
Aufsatz
Co-Creation durch Peers im digitalen Lernen – Wie Plattformen und Chatbots die Partizipation bei der Lernmaterialerstellung begleiten können
(2020-07-07)
Die Arbeit in Industrieunternehmen verändert sich auf Grund der Digitalisierung grundlegend. Entwicklungen in der Automatisierungstechnik können in naher Zukunft einen Teil der Arbeit von Arbeitnehmenden ersetzen. Dadurch wird es notwendig sein, sich auf die sich schnell wechselnden Qualifikationsanforderungen aus diesem Digitalisierungsprozess einzustellen. Hierzu gehört einerseits die schnelle Reaktionsfähigkeit auf die fortlaufenden Veränderungen, die in Unternehmen stattfinden, beispielsweise die Einbettung neuer ...
Aufsatz
Influence of Different Hot Runner-Systems in the Injection Molding Process on the Structural and Mechanical Properties of Regenerated Cellulose Fiber Reinforced Polypropylene
(2023-04-18)
The increasing demand for renewable raw materials and lightweight composites leads to an increasing request for natural fiber composites (NFC) in series production. In order to be able to use NFC competitively, they must also be processable with hot runner systems in injection molding series production. For this reason, the influences of two hot runner systems on the structural and mechanical properties of Polypropylene with 20 wt.% regenerated cellulose fibers (RCF) were investigated. Therefore, the material was ...
Aufsatz
Additive Timber Manufacturing: A Novel, Wood-Based Filament and Its Additive Robotic Fabrication Techniques for Large-Scale, Material-Efficient Construction
(2021-08-13)
Additive manufacturing (AM), as resource-efficient fabrication processes, could also be used in the dimensions of the construction industry, as a variety of experimental projects using concrete and steel demonstrate. In timber construction, currently few additive technologies have been developed having the potential to be used in large scale. Currently known AM processes use wood in pulverized form, losing its inherent structural and mechanical properties. This research proposes a new material that maintains a complete ...
Aufsatz
Pile covering of waste disposal using technosols made of municipal solid waste incineration bottom ash and coal combustion residues: A column leaching experiment
(2023-03-10)
Technosols are characterized by a substantial quantity of artifacts or industrial wastes in the upper 100 cm. They can be used as cover caps in mining rehabilitation, in which vegetation cover is subsequently established. However, prolific vegetation growth can be limited by the chemical and physical properties of technogenic substrates. As further studies need to be conducted to evaluate the suitability of municipal solid waste incineration bottom ash and coal combustion residues as cover caps, the pH, electrical ...
Aufsatz
Development of a hybrid mixed-mode solar dryer for product drying
(2023-02-28)
Sun drying in the open air is quite popular worldwide. However, the use of solar dryers to preserve various perishable agricultural products is a relatively new area of study, and the long-term effects of this method are not yet fully understood. The slow drying process in direct sunlight can contaminate the dried materials by soil and insects. To overcome these challenges, we devised a sun drying system that included a heating part, a drying area, a portable stand, fans, and a 50-W photovoltaic panel. An alternate ...
Aufsatz
Does liming improve microbial carbon use efficiency after maize litter addition in a tropical acidic soil?
(2023-04-26)
Soil pH is one of the main drivers of soil microbial functions, including carbon use efficiency (CUE), the efficiency of microorganisms in converting substrate C into biomass, a key parameter for C sequestration. We evaluated liming effects after maize-litter addition on total CUE (including microbial residues), CUE of microbial biomass (CUEMB), and fungal biomass on an acidic Acrisol with a low C. We established a 6-week incubation experiment to compare limed and unlimed Acrisol treatments and a reference soil, a ...
Aufsatz
Reduction Behavior of Anisyl-substituted P-Ferrocenyl Phospholes
(2023-05-26)
P-Ferrocenylphospholes with differing substituents in α-position have been synthesized and their identity and purity was confirmed using multinuclear NMR spectroscopy, MS, elemental analysis and single crystal X-ray diffraction. Furthermore, the redox properties have been explored with electrochemical measurements. Transferring the reduction to a preparative scale using lithium leads to reductive P−C bond cleavage furnishing the corresponding phospholide which has been transformed to P-tert-butyl substituted phosphole. ...
Aufsatz
Attitude maneuvers avoiding forbidden directions
(2023-06-16)
Many space missions require the execution of large-angle attitude slews during which stringent pointing constraints must be satisfied. For example, the pointing direction of a space telescope must be kept away from directions to bright objects, maintaining a prescribed safety margin. In this paper we propose an open-loop attitude control algorithm which determines a rest-to-rest maneuver between prescribed attitudes while ensuring that any of an arbitrary number of body-fixed directions of light-sensitive instruments ...