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Zur Synthese der Hühnerinsulin-A-Kette, I : Darstellung der Fragmente A1–8, A9–15, A1–7 und A8–15
(1979)
Ukiyo kommt aus dem Japanischen und bedeutet übersetzt so viel wie: „Den Moment leben, ohne von den Sorgen des Lebens berührt zu werden.“ Gerade in Zeiten der Pandemie verliert man oft den Blick für das Schöne im Leben. Der Fotoband „UKIYO“ soll dazu anregen, alltägliche Dinge aus einem neuen Blickwinkel zu betrachten und die Schönheit im Vergänglichen zu erkennen. Die Fotografien sind inspiriert durch das japanische Kunstgenre Ukiyo-e, was wörtlich übersetzt etwa „Bilder der heiteren, fließenden Welt“ heißt. Die Gestaltung des Bildbandes orientiert sich an verschiedenen japanischen Stilmitteln, wie zum Beispiel Wabi-Sabi (die Schönheit im Unvollkommenen) und Mono no aware (eine melancholische Mischung aus Freude, Trauer und Hinnahme). „UKIYO“ nimmt die Betrachter mit auf eine kleine Reise durch die fließende Welt.
Thermal Characterization of additive manufactured Integral Structures for Phase Change Applications
(2020)
“Infused Thermal Solutions” (ITS) introduces a method for passive thermal control to stabilize structural components thermally without active heating and cooling systems, by using phase change material (PCM) in combination with lattice – both embedded into an additive manufactured integral structure. The technology is currently under development. This paper presents the results of the thermal property measurements performed on additive manufactured ITS breadboards. Within the breadboard campaigns key characteristics of the additive manufactured specimens were derived: Mechanical parameters: specimen impermeability, minimum wall thickness, lattice structure, subsequent heat treatment. Thermal properties: thermo-optical surface properties of the additive manufactured raw material, thermal conductivity and specific heat capacity measurements. As a conclusion the paper introduces an overview of potential ITS hardware applications, expected to increase the thermal performance.
Infused Thermal Solutions (ITS) introduces a method for passive thermal control to stabilize structural components thermally without active heating and cooling systems, but with phase change material (PCM) for thermal energy storage (TES), in combination with lattice - both embedded in additive manufactured functional structures. In this ITS follow-on paper a thermal model approach and associated predictions are presented, related on the ITS functional breadboards developed at FH Aachen. Predictive TES by PCM is provided by a specially developed ITS PCM subroutine, which is applicable in ESATAN. The subroutine is based on the latent heat storage (LHS) method to numerically embed thermo-physical PCM behavior. Furthermore, a modeling approach is introduced to numerically consider the virtual PCM/lattice nodes within the macro-encapsulated PCM voids of the double wall ITS design. Related on these virtual nodes, in-plane and out-of-plane conductive links are defined. The recent additive manufactured ITS breadboard series are thermally cycled in the thermal vacuum chamber, both with and without embedded PCM. Related on breadboard hardware tests, measurement results are compared with predictions and are subsequently correlated. The results of specific simulations and measurements are presented. Recent predictive results of star tracker analyses are also presented in ICES-2021-106, based on this ITS PCM subroutine.
Neue Perspektiven für die Bahn in der Produktions- und Distributionslogistik durch Prozessautomation
(2019)
Deutschland braucht mehr Eisenbahn um CO2-Emissionen aus dem Verkehr zu reduzieren. Sie muss zum Rückgrat aktueller Logistikprozesse, z.B. bei Kaufmannsgütern und E-Commerce, werden. Dies geht nicht ohne neuartige betriebliche Konzepte und eine Transformation des Güterwagens von einem „dummen Stück Stahl“ zu einem modernen Werkzeug der Logistik.
Als „Güterwagen 4.0“ wird ein kommunikativer und kooperativer Güterwagen verstanden, der die Voraussetzung zur Automatisierung aller Prozesse der Zugvorbereitung bereitstellt, sich aber ansonsten vollkommen kompatibel mit heutigen Betriebsverfahren im Hauptlauf präsentiert. Durch Kommunikation zwischen Güterwagen und umgebenden intelligenten Systemen im Sinne eines „Internet der Dinge“ gelingt damit unter Anderem die Realisierung hoch effizienter Gleisanschlussverkehre, die der Güterbahn neue Märkte abseits der klassisch bahn-affinen Verkehre erschließen und letztlich den Wandel zu einer nachhaltigen Gütermobilität fördern.
Neue Perspektiven für die Bahn in der Produktions- und Distributionslogistik durch Prozessautomation
(2020)
Adsorptive Vorbehandlung von Rohglycerin für die 1,3-Propandiol Fermentation mit Clostridium diolis
(2014)
Bei der Gewinnung von Fettsäuren aus Pflanzenölen, z. B. zur Herstellung von Biopolymeren, oder bei der Biodiesel- und Seifenproduktion, fällt Glycerin als Nebenprodukt an. Bei der Biokonversion dieses Rohstoffes zu 1,3-Propandiol wird der Produktionsorganismus Clostridium diolis durch Verunreinigungen im Rohglycerin gehemmt. Als inhibierende Substanzen konnten freie Fettsäuren identifiziert werden. Mithilfe eines adsorptiven Aufarbeitungsverfahrens ist es gelungen, die Fettsäuren zu entfernen und die Konversionseffizienz zu 1,3-Propandiol zu erhöhen.
Due to their anion exchange characteristics, layered double hydroxides (LDHs) are suitable for the detoxification of aqueous, fatty acid containing fermentation substrates. The aim of this study is to examine the adsorption mechanism, using crude glycerol from plant oil esterification as a model system. Changes in the intercalation structure in relation to the amount of fatty acids adsorbed are monitored by X-ray diffraction and infra-red spectroscopy. Additionally, calcination of LDH is investigated in order to increase the binding capacity for fatty acids. Our data propose that, at ambient temperature, fatty acids can be bound to the hydrotalcite by adsorption or in addition by intercalation, depending on fatty acid concentration. The adsorption of fatty acids from crude glycerol shows a BET-like behavior. Above a fatty acid concentration of 3.5 g L−1, intercalation of fatty acids can be shown by the appearance of an increased interlayer spacing. This observation suggests a two phase adsorption process. Calcination of LDHs allows increasing the binding capacity for fatty acids by more than six times, mainly by reduction of structural CO32−.
Die fermentative Verwertung von Rohglycerin setzt je nach Herstellungsmethode und Produktionsorganismus eine Vorbehandlung des Glycerins zur Entfernung von Produktinhibitoren voraus. Durch den Einsatz von Hydrotalcit-Adsorbern können die im Rohglycerin enthaltenen Fettsäuren entfernt werden. Durch diese einfache Aufarbeitungsmethode ist ein mit reinem Glycerin vergleichbarer Umsatz von stark mit Fettsäuren verunreinigtem Rohglycerin zu 1,3-Propandiol (PDO) möglich. Die durch den Hydrotalcit gebundenen Fettsäuren lassen sich mit einem Ethanol-Wasser-Gemisch eluieren. Somit kann der Adsorber regeneriert und die Fettsäuren wieder der Wertschöpfungskette zugeführt werden. Im Fed-Batch-Experiment kann mit C. diolis eine PDO-Konzentration von über 50 g L⁻¹ unter Verwendung des aufgereinigten Rohglycerins erzielt werden. In der industriellen Produktion wird PDO momentan destillativ aufgearbeitet. Ein adsorptives Aufarbeitungsverfahren kann den Energiebedarf des Herstellungsprozesses drastisch senken. Auf der Suche nach einem geeigneten Material wurde ein Adsorberscreening in Bezug auf die Bindungseigenschaften durchgeführt. Mit einem b-Zeolith der Firma Süd ChemieAG konnte bisher die höchste Beladung im Modellsystem von 120 mg PDO/gAdsorber erreicht werden.
Die Lösungsmittelherstellung durch Clostridien konnte wirtschaftlich nicht mit der chemischen Synthese von Lösungsmitteln auf Erdölbasis konkurrieren und wurde in den frühen 1960er Jahren nahezu vollständig eingestellt. Das Interesse an nachwachsenden Rohstoffen hat in den letzten Jahren zu einem Wiederaufleben der ABE-Fermentation geführt. Aufgrund seiner höheren Energiedichte im Vergleich zu Ethanol ist Biobutanol als Energieträgerbesonders interessant und bietet sich z. B. als Produkt einer Bioraffinerie der 2. Generation an. Für die beschriebenen Experimente wird durch das Organosolv-Verfahren aufgeschlossenes Buchenholz verwendet. Der Faserstoff wird mithilfe von CTec2-Enzymen hydrolysiert, wobei der erhaltene Überstand eine Glucosekonzentration von 66 g L⁻¹ aufweist. Auf der Basis dieses Materials können mit Clostridium acetobutylicum Butanol-Ausbeuten erzielt werden, die mit denen unter Verwendung von reinen Zuckern vergleichbar sind. Dem Problem der hohen Produktinhibierung wird mit einer In-situ-Produktaufarbeitung begegnet. Mithilfe von Lösungsmittelimprägnierten Partikeln (SIPs) kann die Produktausbeute drastisch gesteigert werden, indem die gebildeten Lösungsmittel durch das auf dem Partikel imprägnierte Lösungsmittel während der Fermentation extrahiert werden. Zudem wird hierdurch die weitere Produktaufarbeitungstark vereinfacht.
Entwicklung einer Qualitätssicherung für das Laserstrahlschweißen im Vakuum mittels Bildverarbeitung
(2019)
Drink me
(2024)
„Drink me“ ist ein Kurzfilm über drei Freunde auf einer Party, auf der ein mysteriöses Getränk verteilt wird, das die Partygäste in einen besonderen Rausch versetzt. Die Farben fangen an zu leuchten, die Musik wird klarer, alles fühlt sich intensiver an. Bis sich die Wahrnehmung der Protagonistin Ally plötzlich verändert: Vom bunt leuchtenden Rauschzustand zur scheinbaren Realität: Einem grauen, kalten Bunker voller abgewrackter Gestalten. Ally versucht die Party zu verlassen, doch während ihre Wahrnehmungen immer weiter verschwimmen, verliert sie gleichzeitig allmählich ihr Bewusstsein. Der Film bietet durch die Darstellung der verschiedenen Wahrnehmungszustände und das Verschwimmen derer ein visuell besonders spannendes Erlebnis.
Ein 34-jähriger männlicher Patient stellte sich zur Abklärung einer seit dem 9. Lebensjahr bestehenden und im letzten Jahr rasch progredienten Visusminderung beider Augen bei uns vor. Er beschrieb eine subjektiv zunehmende, im Spiegel für ihn selbst sichtbare, weißliche Trübung in der Pupille beidseits und eine starke Blendempfindlichkeit. Nebenbefundlich gab er rezidivierende Konjunktivitiden und morgens verklebte Lider an. Eine Allergie auf Gräserpollen und eine Unverträglichkeit auf Alkohol sowie mehrere Lebensmittel seien ebenfalls bekannt.
Zusätzlich leidet der Patient an stark ausgeprägtem atopischem Ekzem. Dieses wurde nie systemisch, sondern nur bei Bedarf mit kortisonhaltiger Salbe therapiert.
Lagerstabiles flüssiges Wasch- oder Reinigungsmittel enthaltend Proteasen [Offenlegungsschrift]
(2011)
In this article we describe an Internet-of-Things sensing device with a wireless interface which is powered by the oftenoverlooked harvesting method of the Wiegand effect. The sensor can determine position, temperature or other resistively measurable quantities and can transmit the data via an ultra-low power ultra-wideband (UWB) data transmitter. With this approach we can energy-self-sufficiently acquire, process, and wirelessly transmit data in a pulsed operation. A proof-of-concept system was built up to prove the feasibility of the approach. The energy consumption of the system is analyzed and traced back in detail to the individual components, compared to the generated energy and processed to identify further optimization options. Based on the proof-of-concept, an application demonstrator was developed. Finally, we point out possible use cases.
With the growing interest in small distributed sensors for the “Internet of Things”, more attention is being paid to energy harvesting techologies. Reducing or eliminating the need for external power sources or batteries make devices more self-sufficient, more reliable, and reduces maintenance requirements. The Wiegand effect is a proven technology for harvesting small amounts of electrical power from mechanical motion.
This article describes an Internet of things (IoT) sensing device with a wireless interface which is powered by the energy-harvesting method of the Wiegand effect. The Wiegand effect, in contrast to continuous sources like photovoltaic or thermal harvesters, provides small amounts of energy discontinuously in pulsed mode. To enable an energy-self-sufficient operation of the sensing device with this pulsed energy source, the output energy of the Wiegand generator is maximized. This energy is used to power up the system and to acquire and process data like position, temperature or other resistively measurable quantities as well as transmit these data via an ultra-low-power ultra-wideband (UWB) data transmitter. A proof-of-concept system was built to prove the feasibility of the approach. The energy consumption of the system during start-up was analysed, traced back in detail to the individual components, compared to the generated energy and processed to identify further optimization options. Based on the proof of concept, an application prototype was developed.
bulk : Konzeption und Gestaltung einer mobilen Anwendung eines nachhaltigen Unverpackt-Lieferservice
(2022)
Die Welt wird wortwörtlich von Plastik überschwemmt- und trotzdem ist kein Ende des trivialen Verpackungsmaterials in Sicht. Die, die sich den Konsequenzen ihres Konsumverhaltens bewusst sind, haben immer noch keinen flächendeckenden Zugang zu Unverpacktläden und es mangelt schlicht an praktischen Alternativen.
Hier knüpft die App „bulk“ an und schlägt ausschließlich unverpackte Lebensmittel vor – bequem bis zur Haustür geliefert. Das Angebot ist qualitativ hochwertig und meist regional. Für ein positives Kauferlebnis veranschaulicht „bulk“, wie viel Plastik mit den Produkten im Vergleich zu einem konventionellen Wocheneinkauf eingespart werden kann. Das gibt Nutzer:Innen eine Grundlage, ihre Entscheidungen kritisch zu hinterfragen und schult den Blick für den Impact sich summierender Kleinigkeiten.
Konzeption und Gestaltung einer mobilen Anwendung eines nachhaltigen Unverpackt-Lieferservice
(2022)
Die Welt wird wortwörtlich von Plastik überschwemmt - und trotzdem ist kein Ende des trivialen Verpackungsmaterials in Sicht. Die, die sich den Konsequenzen ihres Konsumverhaltens bewusst sind, haben immer noch keinen flächendeckenden Zugang zu Unverpacktläden und es mangelt schlicht an praktischen Alternativen.
Hier knüpft die App „bulk“ an und schlägt ausschließlich unverpackte Lebensmittel vor – bequem bis zur Haustür geliefert. Das Angebot ist qualitativ hochwertig und meist regional. Für ein positives Kauferlebnis veranschaulicht „bulk“, wie viel Plastik mit den Produkten im Vergleich zu einem konventionellen Wocheneinkauf eingespart werden kann. Das gibt Nutzer:Innen eine Grundlage, ihre Entscheidungen kritisch zu hinterfragen und schult den Blick für den Impact sich summierender Kleinigkeiten.
Fast jeder zehnte Mensch in Deutschland hat eine Behinderung. Dennoch gibt es gegenüber diesen Personen eine Menge Vorurteile und unangemessenes Verhalten. Dieses Projekt befasst sich mit der Frage, wie Menschen mit einer Behinderung leben, wie sie denken und welche Rolle Barrieren in ihrem Alltag spielen. Dazu wurden Personen mit unterschiedlichen Lebenseinstellungen und Behinderungen porträtiert. Die Arbeit dokumentiert, inwieweit die Behinderung in ihr Leben und in ihre Persönlichkeit mit einspielt. Die Bilderserie in Kombination mit einem Textteil als Printmedium wird ergänzt durch eine Audiodatei. Dieses Zusammenspiel ist wichtig, um eine Barrierefreiheit der Arbeit zu gewährleisten. Auch die Bindungsform und Schriftgestaltung orientieren sich an barrierefreier Gestaltung. Das Projekt trägt dazu bei, Barrieren aufzuheben - sowohl in unseren Köpfen als auch an Bordsteinkanten.
Concept, scientific research and managerial applications of Provocative Coaching, according to the „Provocative Therapy“ of Prof. Dr. Frank Farrelly (University of Wisconsin, U.S.A) in terms of an application of the Provocative Communication Style in specific situations of practical leadership, especially in the role of a coach for their subordinates.
O Perfil Reiss apresenta no resultado uma visão da estrutura dos motivos e impulsos de uma pessoa. O ponto de saída para a análise do resultado é o conhecimento de que os motivos vitais (= valores e metas de sobrevivência) formam a moldura, na qual as competências e capacidades que uma pessoa possui possam se desabrochar de forma ideal. A partir desse princípio, não existe no Perfil Reiss nenhum resultado que se possa classificar como correto ou falso, nem como bom ou mau. Uma comparação entre o resultado do Perfil Reiss e o conteúdo de uma atividade apresentada ou ambicionada dá informação sobre até que ponto a capacidade de rendimento de uma pessoa nessa posição pode vir ou virá a se desenvolver por um longo tempo.
Para Reiss, a avaliação de cada um dos 16 motivos vitais é a chave para não só entender o comportamento humano, como também para poder prevê-lo. Tal previsão é também a meta de cada ciência. Quando se quer saber a reação das pessoas, precisa-se primeiro descobrir, o que as pessoas realmente querem – e, então prever, que elas satisfarão esses desejos e necessidades em suas ações. As chances, que o Perfil Reiss oferece, resultam entre outras também, que aqui é possível pela primeira vez uma individualização total. Cerca de 6 bilhões de perfis individuais podem ser apresentados com o Perfil Reiss. Na combinação correta da formação e utilização da tipologia de um lado e da individualidade da conclusão de outro lado, está a força positiva desse instrumento.
Um líder excelente está disposto a partilhar a liderança do grupo, a fim de iniciar o desenvolvimento de nosso Team. Pois: Um grupo somente alcançará sua plenipotência, se o seu líder estiver disposto a partilhar a liderança. Em princípio, múltiplos conteúdos podem – em diferentes seqüências – ser tema de um desenvolvimento de Team. Pela experiência, os seguintes temas são os que apresentam os temas difíceis para a eficácia do Team, que necessitam ser tratados. Para cada tema de desenvolvimento é importante tratar de cada um dos passos seguintes no grupo como um todo, para se assegurar uma realização duradoura na prática do grupo.
A explicação do conceito científico de Gestão de competências mostra o valor de desenvolvimento dos subordinarios. Ferramentas práticas explicam o conceito através de experiências de empresas européias. As Competência sao os seguintes: Competência especializada, Competência Metódica, Competência social, Competência individual.
O conceito científico de Lideranca situaçional explica que um líder tem que ser uma pessoa de múltiplas Funções e Competências. Nas empresas alemaes tem muitos pessoas pensando ser líderes, mas no fundo eles são somente Administradores. a diferenca é o seguinte: alguem que é somente capaz de trabalhar com seu conhecimento e com seus ferramentas, já sabe muito, mas isso nao è suficiente para ter sucesso. Ele è de verdade somente um administrador. Pois para ser um Líder de verdade ele precisa além disso as competencias social e individual.
Pensando na motivação de uma perspectiva gerencial, é muito importante ter a seguinte visão: ninguem pode conseguir motivar outras pessoas, mas um lider pode influenciá-las a fazer as coisas com mais entusiasmo. Além disso, ele deve conhecer a sua personalidade mesmo. Ele precisa de reconhecimento dos pontos fortes e fracos proprios. Quem – por exemplo – é bem fechado, precisa desenvolver mais forca para motivar as outras pessoas. Quem – por outro exemplo – adora de fazer todas coisas sozinho, vai ter dificuldades com delegação para seus funcionarios. Se ele sabe desse ponto fraco proprio, ele pode evitar esse ponto fraco e delegar de verdade. Para conseguir essa meta, um dialogo de ´feedback´ com os funcionarios e muito importante para descobrir as diferenças entre a auto-percepção e o percepção dos outros, por exemplo sobre o estilo de liderança aplicada.
Os 3 items majores: a explicação do conceito científico, depois praticar o conceito através de uma auto-avaliação, e no final algumas experiências de empresários européias. Um Líder de Sucesso deve ser - como diz o ditado - "um Pau para toda Obra", uma pessoa de múltiplas Funções e Competências. Em geral são as competências requeridas de um Líder de Sucesso as 4 seguintes: 1. Competência especializada 2. Competência Metódica 3. Competência social 4. Competência individual.
Many companies still conduct the worldwide management of people as if neither the external economic nor the internal structure of the firm had changed. The costs of cross-cultural failure, for individuals and their companies, are enormous: personal and family costs; financial, professional and emotional costs; costs to one’s career prospects, to one’s self-esteem, to one’s marriage and family. This scenario describes sufficiently the reason for learning “the art of crossing cultures” (Craig Storti). To this end, this research paper describes an innovative approach of cross-cultural training, following the didactical ideas of Kolb and Fry, the so-called 'experiential learning'.
Unternehmenskultur
(1993)
Inhaltsverzeichnis:
I. Lern- und Arbeitstechniken im 1. und im 10. Semester
II. Lern- und Arbeitstechniken als persönliches Selbstmanagement
III. Diskussionsfragen und -thesen
IV. Was heißt: Eigenverantwortung im Studium?
V. Eigenverantwortung als gelebte Freiheit von Studierenden
VI. Warum es unmöglich ist, Verantwortung an Studierende zu delegieren VII. Erziehungsauftrag: Studierende in ihrer Eigenverantwortung belassen VIII. Folgerungen für Lehrende IX. Folgerungen für Studierende
Von Daniel Düsentrieb zu Dagobert Duck. Trinationale Master Class in High-Tech Entrepreneurship
(2009)
Endlich! Nach über zwei Jahren kulturellen Stillstands richtet der Musiknetzwerk Aachen e.V. ein Festival aus. Die Bachelorandin Jana Wetzlar übernimmt hierbei die Veranstaltungsplanung und -bewerbung. Der erste Teil der Arbeit umfasst die Erarbeitung eines einzigartigen Festivalkonzepts, bei dem die Förderung von jungen Newcomerkünstler:innen und die ökologische Nachhaltigkeit der Veranstaltung im Vordergrund stehen. Eine weitere Besonderheit stellt das paritätisch besetzte Künstler:innen-Line-Up dar. Im zweiten Teil der Arbeit wurden eine umfangreiche Werbekampagne sowie ein passendes Corporate Design entwickelt, die die Besonderheiten des Festivals hervorheben und viele Festivalbesucher:innen generieren sollen. Die übergeordneten Ziele der Arbeit bestehen darin, einen Beitrag zur gesellschaftlichen Etablierung des Musiknetzwerk Aachen e.V. zu leisten und die Voraussetzungen für ein jährlich wiederkehrendes Festival zu schaffen.
Die Einleitung zur Norm DIN EN 62305-3 beschreibt klar und ein - deutig: Der vorliegende Teil der IEC 62305 behandelt den Schutz von baulichen Anlagen gegen materielle Schäden und den Schutz von Personen gegen Verletzungen durch Berührungs- und Schrittspannungen. Als das wesentlichste und effektivste Mittel zum Schutz von baulichen Anlagen gegen materielle Schäden gilt das Blitz - schutzsystem (LPS).
Im Projekt „Fensterleben” werden Alltagsgeschichten, die sich vor und in einer Erdgeschosswohnung abspielen, graphisch als Videos aufbereitet. In einer mehrteiligen Serie werden die Eindrücke und Perspektiven auf „Bürgersteig-Geschehnisse” und was hinter den Fenstern passiert, veranschaulicht. Besonderes Interesse gilt dem Zusammenspiel von privatem und öffentlichem Raum: was wurde zwischen Fensterbank und Bürgersteig ausgetauscht und weitergegeben.
Glucose oxidase (GOx) is an enzyme frequently used in glucose biosensors. As increased temperatures can enhance the performance of electrochemical sensors, we investigated the impact of temperature pulses on GOx that was drop-coated on flattened Pt microwires. The wires were heated by an alternating current. The sensitivity towards glucose and the temperature stability of GOx was investigated by amperometry. An up to 22-fold increase of sensitivity was observed. Spatially resolved enzyme activity changes were investigated via scanning electrochemical microscopy. The application of short (<100 ms) heat pulses was associated with less thermal inactivation of the immobilized GOx than long-term heating.
Light-addressable potentiometric sensors (LAPS) are semiconductor-based potentiometric sensors, with the advantage to detect the concentration of a chemical species in a liquid solution above the sensor surface in a spatially resolved manner. The addressing is achieved by a modulated and focused light source illuminating the semiconductor and generating a concentration-depending photocurrent. This work introduces a LAPS set-up that is able to monitor the electrical impedance in addition to the photocurrent. The impedance spectra of a LAPS structure, with and without illumination, as well as the frequency behaviour of the LAPS measurement are investigated. The measurements are supported by electrical equivalent circuits to explain the impedance and the LAPS-frequency behaviour. The work investigates the influence of different parameters on the frequency behaviour of the LAPS. Furthermore, the phase shift of the photocurrent, the influence of the surface potential as well as the changes of the sensor impedance will be discussed.
Light-addressable potentiometric sensors (LAPS) are field-effect-based sensors. A modulated light source is used to define the particular measurement spot to perform spatially resolved measurements of chemical species and to generate chemical images. In this work, an organic-LED (OLED) display has been chosen as a light source. This allows high measurement resolution and miniaturisation of the system. A new developed driving method for the OLED display optimised for LAPS-based measurements is demonstrated. The new method enables to define modulation frequencies between 1 kHz and 16 kHz and hence, reduces the measurement time of a chemical image by a factor of 40 compared to the traditional addressing of an OLED display.
Semiconductor-based chemical imaging sensors, like the light-addressable potentiometric sensor (LAPS) or the pH-imaging sensor based on a charge-coupled device (CCD), are becoming a powerful tool for label-free imaging of biological phenomena. We have proposed a polyion-based enzymatic membrane to develop an acetylcholine (ACh) imaging sensor for neural cell-activity observations. In this study, a CCD-type ACh-imaging sensor and a LAPS-type ACh-imaging sensor were fabricated and the prospect of both sensors was clarified by making a comparison of their basic characteristics.
Ein lichtadressierbarer potentiometrischer Sensor (LAPS) kann die Konzentration eines oder mehrerer Analyten ortsaufgelöst auf der Sensoroberfläche nachweisen. Dazu wird mit einer modulierten Lichtquelle die Halbleiterstruktur des zu untersuchenden Bereiches angeregt und ein entsprechender Photostrom ausgelesen. Durch gleichzeitige Anregung mehrere Bereiche durch Lichtquellen mit unterschiedlichen Modulationsfrequenzen können diese auch zeitgleich ausgelesen werden. Mit der neuen, hier vorgestellten Ansteuerungselektronik integriert in einem "Field Programmable Gate Array" (FPGA) ist es möglich, mehrere Leuchtquellen gleichzeitig mit unterschiedlichen, während der Laufzeit festlegbaren Frequenzen, Phasen und Lichtintensitäten zu betreiben. Somit kann das Frequenzverhalten des Sensors untersucht und die Konzentration des Analyten über das Oberflächenpotential mit Hilfe von Strom/Spannungs-Kurven und Phase/Spannungs-Kurven bestimmt werden.
A light-addressable potentiometric sensor (LAPS) can measure the concentration of one or several analytes at the sensor surface simultaneously in a spatially resolved manner. A modulated light pointer stimulates the semiconductor structure at the area of interest and a responding photocurrent can be read out. By simultaneous stimulation of several areas with light pointers of different modulation frequencies, the read out can be performed at the same time. With the new proposed controller electronic based on a field-programmable gate array (FPGA), it is possible to control the modulation frequencies, phase shifts, and light brightness of multiple light pointers independently and simultaneously. Thus, it is possible to investigate the frequency response of the sensor, and to examine the analyte concentration by the determination of the surface potential with the help of current/voltage curves and phase/voltage curves. Additionally, the ability to individually change the light intensities of each light pointer is used to perform signal correction.
To study chemical and biological processes, spatially resolved determination of the concentrations of one or more analyte species is of distinct interest. With a light-addressable potentiometric sensor (LAPS), chemical images can be created, which visualize the concentration distribution above the sensor plate. One important challenge is to achieve a good lateral resolution in order to detect events that take place in a small and limited region. LAPS utilizes a focused light spot to address the measurement region. By moving this light spot along the semiconductor sensor plate, the concentration distribution can be observed. In this study, we show that utilizing a pulse as light excitation instead of a traditionally used continuously modulated light excitation, the lateral resolution can be improved by a factor of 6 or more.
Kompakter Aufbau eines lichtadressierbaren potentiometrischen Sensors mit verfahrbarem Diodenlaser
(2011)
Bestimmung der metabolischen Aktivität von Mikroorganismen während des Biogasbildungsprozesses
(2009)
The compliant nature of distal limb muscle-tendon units is traditionally considered suboptimal in explosive movements when positive joint work is required. However, during accelerative running, ankle joint net mechanical work is positive. Therefore, this study aims to investigate how plantar flexor muscle-tendon behavior is modulated during fast accelerations. Eleven female sprinters performed maximum sprint accelerations from starting blocks, while gastrocnemius muscle fascicle lengths were estimated using ultrasonography. We combined motion analysis and ground reaction force measurements to assess lower limb joint kinematics and kinetics, and to estimate gastrocnemius muscle-tendon unit length during the first two acceleration steps. Outcome variables were resampled to the stance phase and averaged across three to five trials. Relevant scalars were extracted and analyzed using one-sample and two-sample t-tests, and vector trajectories were compared using statistical parametric mapping. We found that an uncoupling of muscle fascicle behavior from muscle-tendon unit behavior is effectively used to produce net positive mechanical work at the joint during maximum sprint acceleration. Muscle fascicles shortened throughout the first and second steps, while shortening occurred earlier during the first step, where negative joint work was lower compared with the second step. Elastic strain energy may be stored during dorsiflexion after touchdown since fascicles did not lengthen at the same time to dissipate energy. Thus, net positive work generation is accommodated by the reuse of elastic strain energy along with positive gastrocnemius fascicle work. Our results show a mechanism of how muscles with high in-series compliance can contribute to net positive joint work.
Training-induced increase in Achilles tendon stiffness affects tendon strain pattern during running
(2019)
Background
During the stance phase of running, the elasticity of the Achilles tendon enables the utilisation of elastic energy and allows beneficial contractile conditions for the triceps surae muscles. However, the effect of changes in tendon mechanical properties induced by chronic loading is still poorly understood. We tested the hypothesis that a training-induced increase in Achilles tendon stiffness would result in reduced tendon strain during the stance phase of running, which would reduce fascicle strains in the triceps surae muscles, particularly in the mono-articular soleus.
Methods
Eleven subjects were assigned to a training group performing isometric singleleg plantarflexion contractions three times per week for ten weeks, and another ten subjects formed a control group. Before and after the training period, Achilles tendon stiffness was estimated, and muscle-tendon mechanics were assessed during running at preferred speed using ultrasonography, kinematics and kinetics.
Results
Achilles tendon stiffness increased by 18% (P <0:01) in the training group, but the associated reduction in strain seen during isometric contractions was not statistically significant. Tendon elongation during the stance phase of running was similar after training, but tendon recoil was reduced by 30% (P <0:01), while estimated tendon force remained unchanged. Neither gastrocnemius medialis nor soleus fascicle shortening during stance was affected by training.
Discussion
These results show that a training-induced increase in Achilles tendon
stiffness altered tendon behaviour during running. Despite training-induced changes in tendon mechanical properties and recoil behaviour, the data suggest that fascicle shortening patterns were preserved for the running speed that we examined. The asymmetrical changes in tendon strain patterns supports the notion that simple inseries models do not fully explain the mechanical output of the muscle-tendon unit during a complex task like running.
Modulation of muscle-tendon interaction in the human triceps surae during an energy dissipation task
(2017)
During rapid deceleration of the body, tendons buffer part of the elongation of the muscle-tendon unit (MTU), enabling safe energy dissipation via eccentric muscle contraction. Yet, the influence of changes in tendon stiffness within the physiological range upon these lengthening contractions is unknown. This study aimed to examine the effect of training-induced stiffening of the Achilles tendon on triceps surae muscle-tendon behavior during a landing task. Twenty-one male subjects were assigned to either a 10-week resistance-training program consisting of single-leg isometric plantarflexion (n = 11) or to a non-training control group (n = 10). Before and after the training period, plantarflexion force, peak Achilles tendon strain and stiffness were measured during isometric contractions, using a combination of dynamometry, ultrasound and kinematics data. Additionally, testing included a step-landing task, during which joint mechanics and lengths of gastrocnemius and soleus fascicles, Achilles tendon, and MTU were determined using synchronized ultrasound, kinematics and kinetics data collection. After training, plantarflexion strength and Achilles tendon stiffness increased (15 and 18%, respectively), and tendon strain during landing remained similar. Likewise, lengthening and negative work produced by the gastrocnemius MTU did not change detectably. However, in the training group, gastrocnemius fascicle length was offset (8%) to a longer length at touch down and, surprisingly, fascicle lengthening and velocity were reduced by 27 and 21%, respectively. These changes were not observed for soleus fascicles when accounting for variation in task execution between tests. These results indicate that a training-induced increase in tendon stiffness does not noticeably affect the buffering action of the tendon when the MTU is rapidly stretched. Reductions in gastrocnemius fascicle lengthening and lengthening velocity during landing occurred independently from tendon strain. Future studies are required to provide insight into the mechanisms underpinning these observations and their influence on energy dissipation.
Dynamic retinal vessel analysis (DVA) provides a non-invasive way to assess microvascular function in patients and potentially to improve predictions of individual cardiovascular (CV) risk. The aim of our study was to use untargeted machine learning on DVA in order to improve CV mortality prediction and identify corresponding response alterations.
Immunosorbent turnip vein clearing virus (TVCV) particles displaying the IgG-binding domains D and E of Staphylococcus aureus protein A (PA) on every coat protein (CP) subunit (TVCVPA) were purified from plants via optimized and new protocols. The latter used polyethylene glycol (PEG) raw precipitates, from which virions were selectively re-solubilized in reverse PEG concentration gradients. This procedure improved the integrity of both TVCVPA and the wild-type subgroup 3 tobamovirus. TVCVPA could be loaded with more than 500 IgGs per virion, which mediated the immunocapture of fluorescent dyes, GFP, and active enzymes. Bi-enzyme ensembles of cooperating glucose oxidase and horseradish peroxidase were tethered together on the TVCVPA carriers via a single antibody type, with one enzyme conjugated chemically to its Fc region, and the other one bound as a target, yielding synthetic multi-enzyme complexes. In microtiter plates, the TVCVPA-displayed sugar-sensing system possessed a considerably increased reusability upon repeated testing, compared to the IgG-bound enzyme pair in the absence of the virus. A high coverage of the viral adapters was also achieved on Ta2O5 sensor chip surfaces coated with a polyelectrolyte interlayer, as a prerequisite for durable TVCVPA-assisted electrochemical biosensing via modularly IgG-assembled sensor enzymes.
In this review article, we are going to present an overview on possible applications of light-addressable electrodes (LAE) as actuator/manipulation devices besides classical electrode structures. For LAEs, the electrode material consists of a semiconductor. Illumination with a light source with the appropiate wavelength leads to the generation of electron-hole pairs which can be utilized for further photoelectrochemical reaction. Due to recent progress in light-projection technologies, highly dynamic and flexible illumination patterns can be generated, opening new possibilities for light-addressable electrodes. A short introduction on semiconductor–electrolyte interfaces with light stimulation is given together with electrode-design approaches. Towards applications, the stimulation of cells with different electrode materials and fabrication designs is explained, followed by analyte-manipulation strategies and spatially resolved photoelectrochemical deposition of different material types.
In lab-on-chip systems, electrodes are important for the manipulation (e.g., cell stimulation, electrolysis) within such systems. An alternative to commonly used electrode structures can be a light-addressable electrode. Here, due to the photoelectric effect, the conducting area can be adjusted by modification of the illumination area which enables a flexible control of the electrode. In this work, titanium dioxide based light-addressable electrodes are fabricated by a sol–gel technique and a spin-coating process, to deposit a thin film on a fluorine-doped tin oxide glass. To characterize the fabricated electrodes, the thickness, and morphological structure are measured by a profilometer and a scanning electron microscope. For the electrochemical behavior, the dark current and the photocurrent are determined for various film thicknesses. For the spatial resolution behavior, the dependency of the photocurrent while changing the area of the illuminated area is studied. Furthermore, the addressing of single fluid compartments in a three-chamber system, which is added to the electrode, is demonstrated.
Photoelectrochemical (PEC) biosensors are a rather novel type of biosensors thatutilizelighttoprovideinformationaboutthecompositionofananalyte,enablinglight-controlled multi-analyte measurements. For enzymatic PEC biosensors,amperometric detection principles are already known in the literature. In con-trast, there is only a little information on H+-ion sensitive PEC biosensors. Inthis work, we demonstrate the detection of H+ions emerged by H+-generatingenzymes, exemplarily demonstrated with penicillinase as a model enzyme on atitanium dioxide photoanode. First, we describe the pH sensitivity of the sensorand study possible photoelectrocatalytic reactions with penicillin. Second, weshow the enzymatic PEC detection of penicillin.
The feasibility of light-addressed detection and manipulation of pH gradients inside an electrochemical microfluidic cell was studied. Local pH changes, induced by a light-addressable electrode (LAE), were detected using a light-addressable potentiometric sensor (LAPS) with different measurement modes representing an actuator-sensor system. Biosensor functionality was examined depending on locally induced pH gradients with the help of the model enzyme penicillinase, which had been immobilized in the microfluidic channel. The surface morphology of the LAE and enzyme-functionalized LAPS was studied by scanning electron microscopy. Furthermore, the penicillin sensitivity of the LAPS inside the microfluidic channel was determined with regard to the analyte’s pH influence on the enzymatic reaction rate. In a final experiment, the LAE-controlled pH inhibition of the enzyme activity was monitored by the LAPS.
A capacitive electrolyte-insulator-semiconductor (EISCAP) biosensor modified with Tobacco mosaic virus (TMV) particles for the detection of acetoin is presented. The enzyme acetoin reductase (AR) was immobilized on the surface of the EISCAP using TMV particles as nanoscaffolds. The study focused on the optimization of the TMV-assisted AR immobilization on the Ta 2 O 5 -gate EISCAP surface. The TMV-assisted acetoin EISCAPs were electrochemically characterized by means of leakage-current, capacitance-voltage, and constant-capacitance measurements. The TMV-modified transducer surface was studied via scanning electron microscopy.
Acetoin and diacetyl have a major impact on the flavor of alcoholic beverages such as wine or beer. Therefore, their measurement is important during the fermentation process. Until now, gas chromatographic techniques have typically been applied; however, these require expensive laboratory equipment and trained staff, and do not allow for online monitoring. In this work, a capacitive electrolyte–insulator–semiconductor sensor modified with tobacco mosaic virus (TMV) particles as enzyme nanocarriers for the detection of acetoin and diacetyl is presented. The enzyme acetoin reductase from Alkalihalobacillus clausii DSM 8716ᵀ is immobilized via biotin–streptavidin affinity, binding to the surface of the TMV particles. The TMV-assisted biosensor is electrochemically characterized by means of leakage–current, capacitance–voltage, and constant capacitance measurements. In this paper, the novel biosensor is studied regarding its sensitivity and long-term stability in buffer solution. Moreover, the TMV-assisted capacitive field-effect sensor is applied for the detection of diacetyl for the first time. The measurement of acetoin and diacetyl with the same sensor setup is demonstrated. Finally, the successive detection of acetoin and diacetyl in buffer and in diluted beer is studied by tuning the sensitivity of the biosensor using the pH value of the measurement solution.
Utilizing an appropriate enzyme immobilization strategy is crucial for designing enzyme-based biosensors. Plant virus-like particles represent ideal nanoscaffolds for an extremely dense and precise immobilization of enzymes, due to their regular shape, high surface-to-volume ratio and high density of surface binding sites. In the present work, tobacco mosaic virus (TMV) particles were applied for the co-immobilization of penicillinase and urease onto the gate surface of a field-effect electrolyte-insulator-semiconductor capacitor (EISCAP) with a p-Si-SiO₂-Ta₂O₅ layer structure for the sequential detection of penicillin and urea. The TMV-assisted bi-enzyme EISCAP biosensor exhibited a high urea and penicillin sensitivity of 54 and 85 mV/dec, respectively, in the concentration range of 0.1–3 mM. For comparison, the characteristics of single-enzyme EISCAP biosensors modified with TMV particles immobilized with either penicillinase or urease were also investigated. The surface morphology of the TMV-modified Ta₂O₅-gate was analyzed by scanning electron microscopy. Additionally, the bi-enzyme EISCAP was applied to mimic an XOR (Exclusive OR) enzyme logic gate.
Plakatzeichen : Plakate mit Schrift über Schrift ; 50 typografische Plakate ; Kommunikationsdesign
(2013)
In the Laser Powder Bed Fusion (LPBF) process, parts are built out of metal powder material by exposure of a laser beam. During handling operations of the powder material, several influencing factors can affect the properties of the powder material and therefore directly influence the processability during manufacturing. Contamination by moisture due to handling operations is one of the most critical aspects of powder quality. In order to investigate the influences of powder humidity on LPBF processing, four materials (AlSi10Mg, Ti6Al4V, 316L and IN718) are chosen for this study. The powder material is artificially humidified, subsequently characterized, manufactured into cubic samples in a miniaturized process chamber and analyzed for their relative density. The results indicate that the processability and reproducibility of parts made of AlSi10Mg and Ti6Al4V are susceptible to humidity, while IN718 and 316L are barely influenced.
Flow separation is a phenomenon that occurs in all kinds of supersonic nozzles sometimes during run-up and shut-down operations. Especially in expansion nozzles of rocket engines with large area ratio, flow separation can trigger strong side loads that can damage the structure of the nozzle. The investigation presented in this paper seeks to establish measures that may be applied to alter the point of flow separation. In order to achieve this, a supersonic nozzle was placed at the exit plane of the conical nozzle. This resulted in the generation of cross flow surrounding the core jet flow from the conical nozzle. Due to the entrainment of the gas stream from the conical nozzle the pressure in its exit plane was found to be lower than that of the ambient. A Cold gas instead of hot combustion gases was used as the working fluid. A mathematical simulation of the concept was validated by experiment. Measurements confirmed the simulation results that due to the introduction of a second nozzle the pressure in the separated region of the conical nozzle was significantly reduced. It was also established that the boundary layer separation inside the conical nozzle was delayed thus allowing an increased degree of overexpansion. The condition established by the pressure measurements was also demonstrated qualitatively using transparent nozzle configurations.
„550 nm“ befasst sich mit dem physiologischen Farbwechsel von Tieren. Einige Fische, Amphibien und Reptilien – wie beispielsweise das Chamäleon oder der Tintenfisch – können ihre Körperfarbe schnell wechseln. Unsere Natur leidet unter Kriegen und dem Klimawandel und verliert dadurch ihre Schönheit. Diese zeichnet sich vor allem durch die beachtliche Diversität der Körperfärbung von Tieren aus. Die Funktionen erstrecken sich über Tarnung, Auflauern oder Warnung bis hin zu einer Werbefärbung. Nicht nur Tiere nutzen Farbe als Ausdrucks- und Kommunikationsmittel. Auch Designer*innen bedienen sich an Farben, um Stimmungen zu vermitteln oder um Aufmerksamkeit und Individualität zu generieren. In „550 nm“ wird das Phänomen des Farbwechsels durch Illustrationen visualisiert und soll als Inspiration für Designinnovationen dienen.