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Biosensor Based on Self-Assembled Films of Graphene Oxide and Polyaniline Using a Field-Effect Device Platform
No full textA new functionalization method to modify capacitive electrolyte–insulator–semiconductor (EIS) structures with nanofilms is presented. Layers of polyallylamine hydrochloride (PAH) and graphene oxide (GO) with the compound polyaniline:poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PANI:PAAMPSA) are deposited onto a p-Si/SiO2 chip using the layer-by-layer technique (LbL). Two different enzymes (urease and penicillinase) are separately immobilized on top of a five-bilayer stack of the PAH:GO/PANI:PAAMPSA-modified EIS chip, forming a biosensor for detection of urea and penicillin, respectively. Electrochemical characterization is performed by constant capacitance (ConCap) measurements, and the film morphology is characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). An increase in the average sensitivity of the modified biosensors (EIS–nanofilm–enzyme) of around 15% is found in relation to sensors, only carrying the enzyme but without the nanofilm (EIS–enzyme). In this sense, the nanofilm acts as a stable bioreceptor onto the EIS chip improving the output signal in terms of sensitivity and stability
Wie ein Stier im Porzellanladen
No full textMenschliche Kommunikation ist geprägt von Sprichwörtern und Redewendungen. Von Generation zu Generation weitergegeben, spiegeln sie Lebenserfahrungen, Traditionen und Moralvorstellungen wider, die sich im Laufe der Zeit im allgemeinen Sprachgebrauch etabliert haben.
Redensarten werden von Menschen auf der ganzen Welt verwendet. Häufig stammen diese bildhaften Vergleiche aus dem Tierreich, was auf die lange gemeinsame Vergangenheit von Tier und Mensch zurückzuführen ist. Bis heute spielen Tiere eine besondere Rolle im Alltag vieler Menschen.
Die Ausdrücke, die in dem Sachbuch „Wie ein Stier im Porzellanladen“ illustrativ und textlich veranschaulicht werden, sind Redensarten über Tiere aus verschiedenen Zeiten, Sprachen und Ländern. Manche werden Lesenden bekannt vorkommen, andere öffnen den Blick für neue Ausdrucksweisen. Sie amüsieren in ihrer faszinierenden Vielfalt durch erfrischenden Humor. Das Buch offenbart auf unterhaltsame Weise, wie ähnlich die Gedanken der Menschen, die sich in spannenden Analogien zwischen Sprachen und Kulturen widerspiegeln, bei näherer Betrachtung eigentlich sind
Potential effects of optical solar sail degredation on trajectory design
No full textThe optical properties of the thin metalized polymer films that are projected for solar sails are assumed to be affected by the erosive effects of the space environment. Their degradation behavior in the real space environment, however, is to a considerable degree indefinite, because initial ground test results are controversial and relevant inspace tests have not been made so far. The standard optical solar sail models that are currently used for trajectory design do not take optical degradation into account, hence its potential effects on trajectory design have not been investigated so far. Nevertheless, optical degradation is important for high-fidelity solar sail mission design, because it decreases both the magnitude of the solar radiation pressure force acting on the sail and also the sail control authority. Therefore, we propose a simple parametric optical solar sail degradation model that describes the variation of the sail film’s optical coefficients with time, depending on the sail film’s environmental history, i.e., the radiation dose. The primary intention of our model is not to describe the exact behavior of specific film-coating combinations in the real space environment, but to provide a more general parametric framework for describing the general optical degradation behavior of solar sails. Using our model, the effects of different optical degradation behaviors on trajectory design are investigated for various exemplary missions
Attitude and orbital modeling of an uncontrolled solar-sail experiment in low-Earth orbit
No full textGossamer-1 is the first project of the three-step Gossamer roadmap, the purpose of which is to develop, prove and demonstrate that solar-sail technology is a safe and reliable propulsion technique for long-lasting and high-energy missions. This paper firstly presents the structural analysis performed on the sail to understand its elastic behavior. The results are then used in attitude and orbital simulations. The model considers the main forces and torques that a satellite experiences in low-Earth orbit coupled with the sail deformation. Doing the simulations for varying initial conditions in attitude and rotation rate, the results show initial states to avoid and maximum rotation rates reached for correct and faulty deployment of the sail. Lastly comparisons with the classic flat sail model are carried out to test the hypothesis that the elastic behavior does play a role in the attitude and orbital behavior of the sai
Mechanical loading on cementoblasts: a mini review
No full textOrthodontic treatments are concomitant with mechanical forces and thereby cause teeth movements. The applied forces are transmitted to the tooth root and the periodontal ligaments which is compressed on one side and tensed up on the other side. Indeed, strong forces can lead to tooth root resorption and the crown-to-tooth ratio is reduced with the potential for significant clinical impact. The cementum, which covers the tooth root, is a thin mineralized tissue of the periodontium that connects the periodontal ligament with the tooth and is build up by cementoblasts. The impact of tension and compression on these cells is investigated in several in vivo and in vitro studies demonstrating differences in protein expression and signaling pathways. In summary, osteogenic marker changes indicate that cyclic tensile forces support whereas static tension inhibits cementogenesis. Furthermore, cementogenesis experiences the same protein expression changes in static conditions as static tension, but cyclic compression leads to the exact opposite of cyclic tension. Consistent with marker expression changes, the singaling pathways of Wnt/ß-catenin and RANKL/OPG show that tissue compression leads to cementum degradation and tension forces to cementogenesis. However, the cementum, and in particular its cementoblasts, remain a research area which should be explored in more detail to understand the underlying mechanism of bone resorption and remodeling after orthodontic treatments
Kritik der digitalen Rationalisierung
No full textDigitalisierung macht’s möglich: mittlerweile beziehen sich Designer:innen in ihrer Konzeptentwicklung immer häufiger auf Referenzdesigns. Sie picken sich die Eigenschaften aus ihnen heraus, von denen sie sich die größte Marktfähigkeit versprechen, und basteln sie zu einem neuen Produkt zusammen. Voilà.
Doch wie unkonventionell kann Design noch sein? Wie viel Luft bleibt der Kreativität unter dem immer enger geschnürten Korsett der Marktfähigkeit?
Alexej Kaspor eröffnet die Diskussion mit einem provokanten Projekt, das einen kritischen Blick in die Zukunft des Industriedesigns wirft.
Dazu fasst er gängige Designprogramme in einer Software zusammen und verbindet sie mit einer künstlichen Intelligenz, die die aktuelle Entwicklung digital rationalisieren und auf die Spitze treiben soll.
Diese führt Meta-Analysen über das Nutzungsverhalten durch und prüft damit Frameworks von Referenzdesigns auf ihre Vermarktbarkeit. Aus diesen entwickelt sie dann Gestaltungsvorschläge, ohne beim Seiltanz zwischen Trendhörigkeit und Scheinindividualismus aus dem Gleichgewicht zu kommen. Innerhalb von Sekunden werden den Designer:innen perfekte Vorschläge übers Metaverse simuliert. Auf dem Silbertablett serviert, übersichtlich und gefährlich einfach. Bereit, kombiniert und in Produktion gebracht zu werden.
Auch mit dem Tracking der KI kann niemand mithalten: um immer am Puls der Zeit zu bleiben, benachrichtigt sie die Designer:innen in Echtzeit über die neuesten Innovationen und Trends.
Ressourcenraubendes Herumprobieren in CAD-Programmen gehört also der Vergangenheit an. Das Programm schafft Abhilfe, und verspricht dabei auch noch die höchste Effizienz, konkret: garantiertes Kapital.
Schlagende Argumente, die die Schwächen der Konsumgesellschaft und Kommerzialisierung gezielt ausgenutzen. Es entsteht die perfekte Marketingmaßnahme, ein genialer Treiber für den Turbokapitalismus. Kram, den niemand braucht und zynische Statussymbole inklusive.
Der Stolz der geltungsbedürftigen Designer:innen wird dabei selbstverständlich nicht untergraben. Sie sollen mitziehen. Mit zahlreichen Notches wird der Erfolg und die Konkurrenzfähigkeit des Produkts prognostiziert und ihnen Honig ums Maul geschmiert.
Die beklemmende Vorahnung wird sich bestätigen. Schritt für Schritt enteignet die KI den Designer:innen ihre Kreativität, bis sie nicht mehr sind als die Kurator:innen berechenbarer Produktkonzepte. Der Spätkapitalismus hat sie in der Mangel.
Versprochen: diese Arbeit lässt niemanden kalt
Responsive integrated small spacecraft solar sail and payload design concepts and missions
No full textAsteroid mining has the potential to greatly reduce the cost of in-space manufacturing, production of propellant for space transportation and consumables for crewed spacecraft, compared to launching the required resources from Earth’s deep gravity well. This paper discusses the top-level mission architecture and trajectory design for these resource-return missions, comparing high-thrust trajectories with continuous low-thrust solar-sail trajectories. This work focuses on maximizing the economic Net Present Value, which takes the time-cost of finance into account and therefore balances the returned resource mass and mission duration. The different propulsion methods will then be compared in terms of maximum economic return, sets of attainable target asteroids, and mission flexibility. This paper provides one more step towards making commercial asteroid mining an economically viable reality by integrating trajectory design, propulsion technology and economic modelling
Model and trajectory optimization for an ideal laser-enhanced solar sail
No full textA laser-enhanced solar sail is a solar sail that is not solely propelled by solar radiation but additionally by a laser beam that illuminates the sail. This way, the propulsive acceleration of the sail results from the combined action of the solar and the laser radiation pressure onto the sail. The potential source of the laser beam is a laser satellite that coverts solar power (in the inner solar system) or nuclear power (in the outer solar system) into laser power. Such a laser satellite (or many of them) can orbit anywhere in the solar system and its optimal orbit (or their optimal orbits) for a given mission is a subject for future research. This contribution provides the model for an ideal laser-enhanced solar sail and investigates how a laser can enhance the thrusting capability of such a sail. The term ”ideal” means that the solar sail is assumed to be perfectly reflecting and that the laser beam is assumed to have a constant areal power density over the whole sail area. Since a laser beam has a limited divergence, it can provide radiation pressure at much larger solar distances and increase the radiation pressure force into the desired direction. Therefore, laser-enhanced solar sails may make missions feasible, that would otherwise have prohibitively long flight times, e.g. rendezvous missions in the outer solar system. This contribution will also analyze exemplary mission scenarios and present optimial trajectories without laying too much emphasis on the design and operations of the laser satellites. If the mission studies conclude that laser-enhanced solar sails would have advantages with respect to ”traditional” solar sails, a detailed study of the laser satellites and the whole system architecture would be the second next ste
The role of environmental factors for the success of digital start-ups
No full textDigital start-ups are perceived as an engine for innovation and job promotor. While success factors for non-IT start-ups have already been extensively researched, this study sheds light on digital entrepreneurs, whose business model relies primarily on services based on digital technologies. Applying the Grounded Theory method, we identify relevant environmental success factors for digital entrepreneurs. The study’s research contribution is threefold. First, we provide 16 relevant and less relevant environmental success factors, which enables a comparison with prior identified factors. We found out that several prior environmental success factors, such as accessibility to transportation or the availability of land and facilities are less relevant for a digital entrepreneur. Second, we derive and discuss hypotheses for the influence of these factors on digital start-up success. Third, we present a theoretical model that lays the foundation for explaining the environmental influence on digital
entrepreneurship success