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Molecular hydrogen production from amorphous solid water during low energy electron irradiation
(2017)
This work investigates the production of molecular hydrogen isotopologues (H2, HD, and D2) during low energy electron irradiation of layered and isotopically labelled thin films of amorphous solid water (ASW) in ultrahigh vacuum. Experimentally, the production of these molecules with both irradiation time and incident electron energy in the range 400 to 500 eV is reported as a function of the depth of a buried D2O layer in an H2O film. H2 is produced consistently in all measurements, reflecting the H2O component of the film, though it does exhibit a modest reduction in intensity at the time corresponding to product escape from the buried D2O layer. In contrast, HD and D2 production exhibit peaks at times corresponding to product escape from the buried D2O layer in the composite film. These features broaden the deeper the HD or D2 is formed due to diffusion. A simple random-walk model is presented that can qualitatively explain the appearance profile of these peaks as a function of the incident electron penetration.
The adsorption of O atoms on the Fe(1 1 0) surface has been investigated by density functional theory for increasing degrees of oxygen coverage from 0.25 to 1 monolayer, to follow the evolution of the Osingle bondFe(1 1 0) system into an FeO(1 1 1)-like monolayer. We found that the quasi-threefold site is the most stable adsorption site for all coverages, with adsorption energies of ∼2.8–4.0 eV per O atom. Oxygen adsorption results in surface geometrical changes such as interlayer relaxation and buckling, the latter of which decreases with coverage. The calculated vibrational frequencies range from 265 to 470 cm−1 for the frustrated translational modes and 480–620 cm−1 for the stretching mode, and hence are in good agreement with the experimental values reported for bulk FeO wüstite. The hybridization of the oxygen 2p and iron 3d orbitals increases with oxygen coverage, and the partial density of states for the Osingle bondFe(1 1 0) system at full coverage resembles the one reported in the literature for bulk FeO. These results at full oxygen coverage point to the incipient formation of an FeO(1 1 1)-like monolayer that would eventually lead to the bulk FeO oxide layer.
The use of vibrational sum-frequency spectroscopy (VSFS) to study transferred graphene, produced by chemical vapour deposition, is presented. The VSF spectrum shows a clear CeH stretching mode at ~2924 cm⁻¹, which is attributed to residue of the polymer used for the transfer. This makes VSFS a powerful tool to identify adsorbates and contaminants affecting the properties of graphene.
This paper presents a cascaded methodology for enhancing the path accuracy of industrial robots by using advanced control schemes. It includes kinematic calibration as well as dynamic modeling and identification. This is followed by a centralized model-based compensation of robot dynamics. The implemented feed-forward torque control shows the expected improvements of control accuracy. However, external measurements show the influence of joint elasticities as systematic path errors. To further increase the accuracy an iterative learning controller (ILC) based on external camera measurements is designed. The implementation yields to significant improvements of path accuracy. By means of a kind of automated ”Teach-In”, an overall effective concept for the automated calibration and optimization of the accuracy of industrial robots in high-dynamic path-applications is realized.
During the transition from conventional towards purely electrical, sustainable mobility, transitional technologies play a major part in the task of increasing adaption rates and decreasing range anxiety. Developing new concepts to meet this challenge requires adaptive test benches, which can easily be modified e.g. when progressing from one stage of development to the next, but also meet certain sustainability demands themselves.
The system architecture presented in this paper is built around a service-oriented software layer, connecting a modular hardware layer for direct access to sensors and actuators to an extensible set of client tools. Providing flexibility, serviceability and ease of use, while maintaining a high level of reusability for its constituent components and providing features to reduce the required overall run time of the test benches, it can effectively decrease the CO2 emissions of the test bench while increasing its sustainability and efficiency.
Background: The topographical correlations between certain extracranial and intracranial osseous points of interest (POIs), and their age-related changes, are indispensable to know for a diagnostical or surgical access to intracranial structures; however, they are difficult to assess with conventional devices.
Materials and methods: In this pilot study, the 3-dimensional coordinates of extra-/intracranial POIs were determined, thus avoiding perspective distortions that used to be intrinsic problems in 2-dimensional morphometry. The data sets were then analysed by creating virtual triangles. The sizes, shapes, and positions of these triangles described the extent and the directions of the age-related shifts of the POIs. A selection of extracranial and intracranial POIs were marked on half skulls of four warmblood horses in two age groups (young: 6 weeks, n = 2; old: 14 and 17 years, n = 2). The x-, y-, and z-coordinates of these POIs were determined with a measurement arm (FaroArm Fusion, FARO Europe®). Direct distances between the POIs as well as their indirect distances on the x-, y-, and z-axis, and angles were calculated.
Results: The analysed virtual triangles revealed that some parts of the skull grew in size, but did not change in shape/relative proportions (proportional type of growth, as displayed by POI A and POI B at the Arcus zygomaticus). The same POIs (A and B) remained in a very stable relationship to their closest intracranial POI at the Basis cranii on the longitudinal axis, however, shifted markedly in the dorso-lateral direction. In contrast, a disproportional growth of other parts of the cranium was, for example, related to POI C at the Crista nuchae, which shifted strongly in the caudal direction with age. A topographically stable reference point (so-called anchor point) at the Basis cranii was difficult to determine.
Conclusions: Two candidates (one at the Synchondrosis intersphenoidalis, another one at the Synchondrosis sphenooccipitalis) were relatively stable in their positions. However, the epicentre of (neuro-)cranial growth could only be pinpointed to an area between them.
One of the main concerns of this publication is to furnish a more rational basis for discussing bioplastics and use fact-based arguments in the public discourse. Furthermore, “Biopolymers – facts and statistics” aims to provide specific, qualified answers easily and quickly for decision-makers in particular from public administration and the industrial sector. Therefore, this publication is made up like a set of rules and standards and largely foregoes textual detail. It offers extensive market-relevant and technical facts presented in graphs and charts, which means that the information is much easier to grasp. The reader can expect comparative market figures for various materials, regions, applications, process routes, agricultural land use, water use or resource consumption, production capacities, geographic distribution, etc.