Search

Efficiency and performance of light triggered molecular motors are crucial features that need to be mechanistically understood to improve the performance and enable conscious property tailoring for specific applications. In this work, three different hemithioindigo‐based molecular motors are investigated and all four steps in their complete unidirectional rotation are unraveled fully quantitatively. Transient absorption spectroscopy across twelve orders of magnitude in time is used to probe the fs nuclear motions up to the ms thermal kinetics, covering the timeframe of the whole motor rotation. The newly known full mechanisms allow simulation of the motor systems to scrutinize their performance at realistic illumination conditions. This highlights the importance of photoisomerization quantum yields for the rotation speed. The substitution pattern in close proximity to the rotation axle influences the excited and ground state properties. Reduction of electron donation and concomitant increase of steric hindrance leads to faster photoisomerization reactions with quasi‐ballistic behavior, but also to a slight decrease in the quantum efficiency. The expected decelerating effects of increased sterics are primarily manifested in the ground state. A promising approach for next‐generation hemithioindigo motors is to elevate electron donation at the rotor fragment followed by an increase of steric hindrance., In a spin: The unidirectional rotation mechanisms of three hemithioindigo based molecular motors are compared fully quantitatively over a dynamic range of twelve orders of magnitude in time.

Molecular motors undergo repetitive directional motions upon external energy input. A profound challenge is the defined transfer of directional motor motions to remote entities at the molecular scale. Herein, we present a molecular setup that allows for the transfer of the directional rotation of a light-powered motor unit onto a remote biaryl axis via an ethylene glycol chain link. Based on a combination of X-ray crystallographic analysis, ECD, and NMR experiments as well as a comprehensive theoretical assessment, we provide evidence for the coupled stepwise directional motions of both molecular units. With the presented setup, facile integration of molecular motor units into larger functional frameworks and complex molecular machines can be explored consciously in the future.

River system measurement and mapping using UAVs is both lean and agile, with the added advantage of increased safety for the surveying crew. A common parameter of fluvial geomorphological studies is the flow velocity, which is a major driver of sediment behavior. Advances in fluid mechanics now include metrics describing the presence and interaction of coherent structures within a flow field and along its boundaries. These metrics have proven to be useful in studying the complex turbulent flows but require time-resolved flow field data, which is normally unavailable in geomorphological studies. Contactless UAV-based velocity measurement provides a new source of velocity field data for measurements of extreme hydrological events at a safe distance, and could allow for measurements of inaccessible areas. Recent works have successfully applied large-scale particle image velocimetry (LSPIV) using UAVs in rivers, focusing predominantly on surficial flow estimation by tracking intensity differences between georeferenced images. The objective of this work is to introduce a methodology for UAV based real-time particle tracking in rivers (RAPTOR) in a case study along a short test reach of the Brigach River in the German Black Forest. This methodology allows for large scale particle tracking velocimetry (LSPTV) using a combination of floating, infrared light-emitting particles and a programmable embedded color vision sensor in order to simultaneously detect and track the positions of objects. The main advantage of this approach is its ability to rapidly collect and process the position data, which can be done in real-time. The disadvantages are that the method requires the use of specialized light-emitting particles, which in some cases cannot be retrieved from the investigation area, and that the method returns velocity data in unscaled units of px/s. This work introduces the RAPTOR system with its hardware, data processing workflow, and provides an example of unscaled velocity field estimation using the proposed method. First experiences with the method show that the tracking rate of 50 Hz allows for position estimation with sub-pixel accuracy, even considering UAV self-motion. A comparison of the unscaled tracks after Savitzky-Golay filtering shows that although the time-averaged velocities remain virtually the same, the filter reduces the standard deviation by more than 40% and the maxima by 20%.

Opioid receptor activation was shown to enhance the efficacy of anti‐neoplastic drugs in several human cancer cell lines. In these cell lines, doxorubicin increased the number of opioid receptors and methadone concurrently enhanced cellular doxorubicin uptake. Triggered through lay press and media, animal owners started to challenge veterinary oncologists with questions about methadone use in anti‐cancer therapy. Especially in veterinary medicine, where side effects of chemotherapy are tolerated to a lesser extent and hence smaller doses are given, agents potentiating chemotherapeutic agents would be an optimal approach to treatment. Canine transitional cell carcinoma cells (TCC, K9TCC), canine osteosarcoma cells (OSA, Abrams) and canine hemangiosarcoma cells (HSA, DAL‐4) were incubated with different combinations of methadone, buprenorphine and doxorubicin, in order to test inhibition of cell proliferation. Opioid receptor density was assessed with fluorescence‐activated cell sorting in drug native and doxorubicin pretreated cells. In TCC and OSA cell lines opioid receptor density increased after doxorubicin pretreatment. In combination treatment, however, we did not find significant potentiation of doxorubicin's inhibitory effect on proliferation in these cell lines. Neither was there a significant increase of the effect of doxorubicin when the opioids were added 24 hr before doxorubicin. Hence, we could not confirm the hypothesis that opioids increase the anti‐proliferative effect of the anti‐neoplastic drug doxorubicin in any of these canine tumour cell lines. The lack of effect on a cellular level does not warrant a clinical approach to use opioids together with doxorubicin in dogs with cancer., Triggered through lay press and media, animal owners started to challenge veterinary oncologists with questions about methadone use in anti‐cancer therapy. However, we could not confirm the hypothesis that opioids increase the anti‐proliferative effect of the anti‐neoplastic drug doxorubicin in any of these canine tumor cell lines. The lack of effect on a cellular level does not warrant a clinical approach to use opioids together with doxorubicin in dogs with cancer.

Carburizing generates different material properties and residual stresses in the carburized layer. A material mechanics based model for endurance prediction of carburized steel components has been developed, in which thin walled tubes are used under cyclic internal and monotonic external pressures allow the determination of the material properties of the carburized layers. An unexpected independence of endurance and mean stress sensitivity from carbon content and hardness has been found, contrary to existing scientific knowledge. Component like specimens were tested to validate the endurance prediction model. The deviations of the predictions from the experiment are in the range of ±8 percent. Das Einsatzharten generiert verschiedene Werkstoffzustande und Eigenspannungen in der Einsatzharteschicht. Fur die Dauerfestigkeitsvorhersage von einsatzgeharteten Bauteilen wurde ein Modell auf werkstoffmechanischer Basis entwickelt. Fur dieses Modell wurden an dunnwandigen Rohrproben mit unterschiedlichem C-Gehalt Dauerfestigkeitsversuche mit zyklischem Innendruck und konstantem Ausendruck durchgefuhrt. Eine unerwartete Unabhangigkeit der Dauerfestigkeit und der Mittelspannungsempfindlichkeit wurde festgestellt, kontrar zum Stand der Wissenschaft. Bauteilahnliche Proben wurden im Ermudungsversuch getestet, um das Dauerfestigkeitsmodell zu validieren. Die Abweichungen der Berechnungen von den Versuchen lagen im Bereich von ±8 Prozent.

The plastic limit load is an important feature of the S-N curve. The classical way of plastic limit load calculation using elastic-ideal plastic material behaviour is restricted to one location of the component. Complex components normally have several fatigue critical locations, for all of them the local plastic limit loads has to be determined. By the classical way the plastic limit load can be evaluated only for one of them. A new method is presented. The local plastic notch factor Kp and the corresponding plastic limit loads are calculated applying Neuber's rule to FE calculations with plastic hardening material. The new method is validated on the basis of six different notched specimens. The need and capability is exemplarily shown on a specimen with two competing failure locations. Die vollplastische Grenzlast ist eine wichtige Kenngrose fur die Bauteilwohlerlinie. Der klassische Weg zur Bestimmung der vollplastischen Grenzlast mithilfe eines elastisch ideal plastischen Materialmodells ist begrenzt auf nur einen kritischen Bereich im Bauteil. Komplexe Bauteile weisen in der Regel mehrere solcher Bereiche auf. Fur alle mussen die vollplastischen Grenzlasten bestimmt werden. Der klassischen Wege erlaubt jedoch nur die Berechnung der vollplastischen Grenzlast fur einen dieser Bereiche. Es wird eine neue Methode vorgestellt, bei der die lokalen plastischen Kerbfaktoren Kp und die zugehorigen plastischen Grenzlasten mithilfe der Neuber Formel auf der Grundlage von FE Berechnungen mit plastisch verfestigendem Materialverhalten bestimmt werden. Die vorgeschlagene Methode wird anhand von sechs unterschiedlichen Kerbstaben validiert. Die Notwendigkeit und die Leistungsfahigkeit der Methode werden exemplarisch an einer Probe mit zwei konkurrierenden Kerben aufgezeigt.

Herein we have demonstrated a DET mechanism used by D. desulfuricans; where the periplasmic cytochromes and hydrogenases play an important role, and Pd nanoparticles bound to the microbes may participate in the electron transfer process. The present work is of importance not only for the fundamental studies of electron transfer processes in microbial physiology and ecology, but also for increased understanding and improvement of the performance of bioelectrochemical techniques e.g. precious metals are extensively used and important catalysts, and therefore present in many industry processing wastewaters. Bio-nanoparticles can oxidize in situ metabolites e.g. H2, formate and ethanol in the anode chambers, while also acting as cathodic catalysts for the oxygen reduction reaction[23]. In addition, this study indicates the feasibility of using bioelectrochemical systems for metal immobilization, recovery or detoxification

Experimental and analytical investigations of constant and variable amplitude fatigue life of not autofrettaged and autofrettaged components have been performed. In variable amplitude loading the new standardised COmmon-RAil-Load sequence CORAL has been used as well as two-level-tests with small cycles at high mean stresses interrupted by large cycles for the evaluation of load sequence effects. The results of the two level tests show that small cycles with amplitudes far below the fatigue limit cause fatigue damage. Life calculations have been performed according to the nominal stress approach with S-N-curves and improved Miner’s Rule, linear-elastic fracture mechanics with 3D-weight functions, elastic-plastic fracture mechanics applying an extended strip yield-model, and explicit 3D-FE-simulation of fatigue crack growth with predefined crack fronts. All approaches are appropriate for predicting realistic variable amplitude lives. From a practical point of view the explicit 3DFE- simulation of fatigue crack growth is too time-consuming. However, such simulations show that the approaches based on linear- elastic fracture mechanics and elastic-plastic fracture mechanics with extended strip yield-model capture the essential physics of fatigue crack growth in a realistic way. Key words: Autofrettage, variable amplitude, residual stress, fatigue crack growth Die Lebensdauer nicht autofrettierter und autofrettierter Bauteile unter einstufiger und betriebsa¨hnlicher Innendruckbelastung wurde experimentell und analytisch untersucht. Als betriebsa¨hnliche Belastung wurde die COmmon-RAil-Load sequence CORAL entwickelt. Zur weiteren Kla¨rung von Lastfolgeeinflu¨ssen wurden Zweistufenversuche durchgefu¨hrt mit dem Ergebnis, dass kleine Schwingspiele noch bei mitteldruckbewerteten Amplituden weit unterhalb der halben Dauerfestigkeit scha¨digen. Die folgenden Lebensdauervorhersagemethoden wurden u¨berpru ¨ft: Nennspannungskonzept mit Varianten der Miner-Regel linear-elastische Bruchmechanik mit 3D-Gewichtsfunktionen elasto-plastische Bruchmechanik mit erweitertem Fliesstreifen- Modell explizite 3D-FE-Simulation des Rissfortschritts mit vorgegebener Rissfront Alle Methoden eignen sich a¨hnlich gut. Fu¨r die praktische Anwendung erscheint die explizite 3D-FE-Simulation zu aufwa¨ndig, sie zeigen jedoch deutlich, dass die linear-elastische Bruchmechanik mit 3D-Gewichtsfunktionen und die elasto-plastische Bruchmechanik mit erweitertem Fliesstreifen-Modell die wesentlichen physikalischen Pha¨nomene des Rissfortschritts realistisch abbilden. Schlu¨sselworte: Autofrettage, Betriebsfestigkeit, Eigenspannungen, Rissfortschritt

The Weakest-Link model is based on defects that are statistically distributed within the material with local stress. The failure at least at one defect causes the failure of the total structure. Based on this model, the so-called statistic size effect can be evaluated in the case of cyclic loading and in the case of static loading the failure behaviour of ferritic steel within the brittle fracture range is highlighted. The application of the Weakest-Link model requires the allocation of the local characteristics - surface and / or volume - to the discrete points of the stress. By using the method “SPIEL” which is independent from the FE code used, the allocation of couples of values -surface and stress and / or volume and stress - by a suitable choice of unit load cases is possible. In consequence of the method “SPIEL” particularities are to be taken into consideration. In the present paper these particularities will be described exemplarily for the FE programs ABAQUS1 and ANSYS2.

Nach dem bisherigen Kenntnisstand haben geschweiste hoherfeste Stahle die gleiche Ermudungsfestigkeit wie geschweiste niedrigfeste Stahle. Um hoherfeste Stahle auch in ermudungsbeanspruchten Konstruktionen effektiv einsetzen zu konnen, bedarf es daher zusatzlicher Anstrengungen, um die Ermudungsfestigkeit zu erhohen, z. B. durch Anwendung von Schweisnahtnachbehandlungsverfahren. Im Stahlbau besteht jedoch bis heute nicht die Moglichkeit, die positiven Effekte einer Schweisnahtnachbehandlung normativ zu berucksichtigen. In dieser Arbeit werden erste Ergebnisse eines laufenden Forschungsprojekts vorgestellt, in dem die Effektivitat des Schweisnahtnachbehandlungsverfahrens WIG-Aufschmelzen und des neuartigen Verfahrens “Ultrasonic Impact Treatment” (UIT) zur Verbesserung der Ermudungsfestigkeit von Schweiskonstruktionen aus hoherfesten Baustahlen untersucht wird. Enhancement of the fatigue strength of welded high strength steels by application of post-weld treatment methods. According to the present state of the art welded high strength steels have the same fatigue strength as welded standard steels. For an effective application of high strength steels in constructions subjected to fatigue are therefore additional efforts necessary in order to improve the fatigue strength, for example by the application of post-weld treatment methods. However up to the present it is not possible to apply the positive effects of these methods in the fatigue design of steel structures. This paper shows first results of a research project, that examines the effectiveness of the post-weld treatment method TIG-dressing and the relatively new method “Ultrasonic Impact Treatment” (UIT) for the improvement of fatigue strength of welded high strength steels.

We report on the first detection of vibrationally labelled compounds by Raman micro-spectroscopy in living cells and demonstrate the feasibility of this technique for bioanalysis. Copyright © 2004 John Wiley & Sons, Ltd.

Die Autofrettage ist ein Verfahren zur Steigerung der Dauerfestigkeit innendruckbelasteter Bauteile. Dabei wird die Dauerfestigkeitssteigerung durch stehenbleibende Risse bestimmt. Im vorgestellten Konzept wird zunachst die mittlere Dauerfestigkeit abgeschatzt. Am Beispiel einer 90° Bohrungsverschneidung wird dieser Schritt erlautert und anhand von experimentellen Ergebnissen validiert. In einem zweiten Schritt werden Dauerfestigkeiten fur geringe Ausfallwahrscheinlichkeiten vorhergesagt. A Design Concept for Autofretted Parts under Pulsating Internal Pressure Autofrettage improves the endurance limit of pressurisized parts. The endurance limit is determined by crack arrest. The design concept first estimates the mean endurance limit, i. e. at a failure probability of 50 percent. This first step is explained in detail by the aid of a cross bore and validated by experimental results of this typical design feature. In a second step the allowable pressure range is predicted for defined low failure probability, typical for series production parts.