Supramolecular assembly and nanoscale morphologies for organic photovoltaic devices

Organic photovoltaics is a field of rapidly growing activity in both research and industry. Flexibility, light-weight, and low-cost render this technique an appealing alternative to silicon based devices for solar energy power conversion. Recently, several donor-acceptor systems have been investigated as active materials for organic photovoltaic devices and it has been shown that the morphology of these heterojunction systems has a severe impact on the device performance. This work focuses on the correlation of nanoscale morphologies of organic donor-acceptor systems with resulting spectroscopic and electronic properties of organic photovoltaic devices. Discotic molecules are used in the active layer of the devices exhibiting a number of properties highly desired for the application in organic photovoltaic devices: The planar core shape of this class of materials allows an assembly to 1-D molecular wires showing anisotropic and exceptionally high charge carrier mobility.It is the aim to establish supramolecular assemblies of the discotic molecules and to realize nanoscale interface morphologies between donor and acceptor compounds in order to optimize the photovoltaic performance of the resulting devices. The impact of residue modifications attached to the disc shaped molecules on morphology, current generation and recombination is analyzed and design rules for these solution processable small molecule blend mixtures are derived. Vacuum sublimation is discussed as an alternative processing route facilitating the fabrication of devices with mixed but also bi-layered active material stacking. Using a dye sensitization method the exciton harvesting and photovoltaic performance can be significantly increased in these thin film devices. A highly ordered nanoscale morphology at the donor-acceptor interface, demonstrated using a template assisted imprinting approach, offers high potential towards photovoltaic devices with interdigitated interfaces and superior power conversion efficiency

Economic optimization of component sizing for residential battery storage systems

Battery energy storage systems (BESS) coupled with rooftop-mounted residential photovoltaic (PV) generation, designated as PV-BESS, draw increasing attention and market penetration as more and more such systems become available. The manifold BESS deployed to date rely on a variety of different battery technologies, show a great variation of battery size, and power electronics dimensioning. However, given today's high investment costs of BESS, a well-matched design and adequate sizing of the storage systems are prerequisites to allow profitability for the end-user. The economic viability of a PV-BESS depends also on the battery operation, storage technology, and aging of the system. In this paper, a general method for comprehensive PV-BESS techno-economic analysis and optimization is presented and applied to the state-of-art PV-BESS to determine its optimal parameters. Using a linear optimization method, a cost-optimal sizing of the battery and power electronics is derived based on solar energy availability and local demand. At the same time, the power flow optimization reveals the best storage operation patterns considering a trade-off between energy purchase, feed-in remuneration, and battery aging. Using up to date technology-specific aging information and the investment cost of battery and inverter systems, three mature battery chemistries are compared; a lead-acid (PbA) system and two lithium-ion systems, one with lithium-iron-phosphate (LFP) and another with lithium-nickel-manganese-cobalt (NMC) cathode. The results show that different storage technology and component sizing provide the best economic performances, depending on the scenario of load demand and PV generation.Web of Science107art. no. 83

Die Masse macht’s?: Erschließungsmethoden und Erkenntnismöglichkeiten bei der Arbeit mit Massenbeständen: eine Einführung

Im Stadtmuseum Dresden wird eine umfangreiche Sammlung Dresdner Bürgerporträts des 19. Jahrhunderts verwahrt. Der Bestand von 2.700 Fotografien auf 2.100 Trägerkartons ist vom Gründungsdirektor des Museums, dem Historiker und Stadtarchivar Otto Richter (1852–1922), zwischen 1892 und 1912 angelegt und von seinen Nachfolgern bis zum Ende der 1930er Jahre fortgeführt worden. Die seither vor allem als Ressource für die Illustration von Publikationen genutzte Sammlung ist in den vergangenen Jahren aus unterschiedlicher Fachperspektive erstmals intensiv erforscht worden. Die Ergebnisse sind unter dem Titel „Die im Licht steh’n. Fotografische Porträts Dresdner Bürger des 19. Jahrhunderts“ in einer Sonderausstellung im Stadtmuseum Dresden (15.2.–12.5.2019) präsentiert und im gleichnamigen Begleitband vorgestellt worden. [Aus der Einleitung.

Die Masse macht‘s? Erschließungsmethoden und Erkenntnismöglichkeiten bei der Arbeit mit Massenbeständen: Vorträge der Tagung am 16. November 2018 im Stadtmuseum Dresden

Der Band enthält die Beiträge der Tagung „Die Masse macht's? Erschließungsmethoden und Erkenntnismöglichkeiten bei der Arbeit mit Massenbeständen“ im Stadtmuseum Dresden am 16. November 2018. Auf Einladung der Veranstalter (Stadtmuseum Dresden, Kustodie der Technischen Universität Dresden, Sächsische Landesstelle für Museumswesen an den Staatlichen Kunstsammlungen Dresden) stellen Fachleute unterschiedlicher Disziplinen Probleme und Lösungen bei der Erschließung, Erforschung und Publikation von kultur-, natur- und wissenschaftshistorischen Massensammlungen zur Diskussion. Dabei ist der Blick über die realen Sammlungen hinaus auf virtuelle Verbundsysteme und digitale Publikationen erweitert worden.The volume contains the contributions of the conference “Do the masses make it? Development methods and knowledge possibilities when working with mass collections” in City Museum Dresden on 16 November 2018. At the invitation of the organizers (City Museum Dresden, Academic Heritage of Technical University Dresden, Saxon State Office for Museum Affairs on the Dresden State Art Collections), experts from various disciplines provide problems and solutions on the development, research and publication of mass collections of cultural, natural and scientific history that will be up for discussion. The view has been extended beyond the real collections to virtual network systems and digital publications

Effect of glucose on assimilatory sulphate reduction in Arabidopsis thaliana roots

With the aim of analysing the relative importance of sugar supply and nitrogen nutrition for the regulation of sulphate assimilation, the regulation of adenosine 5′‐phosphosulphate reductase (APR), a key enzyme of sulphate reduction in plants, was studied. Glucose feeding experiments with Arabidopsis thaliana cultivated with and without a nitrogen source were performed. After a 38 h dark period, APR mRNA, protein, and enzymatic activity levels decreased dramatically in roots. The addition of 0.5% (w/v) glucose to the culture medium resulted in an increase of APR levels in roots (mRNA, protein and activity), comparable to those of plants kept under normal light conditions. Treatment of roots with d‐sorbitol or d‐mannitol did not increase APR activity, indicating that osmotic stress was not involved in APR regulation. The addition of O‐acetyl‐l‐serine (OAS) also quickly and transiently increased APR levels (mRNA, protein, and activity). Feeding plants with a combination of glucose and OAS resulted in a more than additive induction of APR activity. Contrary to nitrate reductase, APR was also increased by glucose in N‐deficient plants, indicating that this effect was independent of nitrate assimilation. [35S]‐sulphate feeding experiments showed that the addition of glucose to dark‐treated roots resulted in an increased incorporation of [35S] into thiols and proteins, which corresponded to the increased levels of APR activity. Under N‐deficient conditions, glucose also increased thiol labelling, but did not increase the incorporation of label into proteins. These results demonstrate that (i) exogenously supplied glucose can replace the function of photoassimilates in roots; (ii) APR is subject to co‐ordinated metabolic control by carbon metabolism; (iii) positive sugar signalling overrides negative signalling from nitrate assimilation in APR regulation. Furthermore, signals originating from nitrogen and carbon metabolism regulate APR synergisticall

Physical Fitness Training in Patients with Subacute Stroke (PHYS-STROKE): multicentre, randomised controlled, endpoint blinded trial

OBJECTIVE: To determine the safety and efficacy of aerobic exercise on activities of daily living in the subacute phase after stroke. DESIGN: Multicentre, randomised controlled, endpoint blinded trial. SETTING: Seven inpatient rehabilitation sites in Germany (2013-17). PARTICIPANTS: 200 adults with subacute stroke (days 5-45 after stroke) with a median National Institutes of Health stroke scale (NIHSS, range 0-42 points, higher values indicating more severe strokes) score of 8 (interquartile range 5-12) were randomly assigned (1:1) to aerobic physical fitness training (n=105) or relaxation sessions (n=95, control group) in addition to standard care. INTERVENTION: Participants received either aerobic, bodyweight supported, treadmill based physical fitness training or relaxation sessions, each for 25 minutes, five times weekly for four weeks, in addition to standard rehabilitation therapy. Investigators and endpoint assessors were masked to treatment assignment. MAIN OUTCOME MEASURES: The primary outcomes were change in maximal walking speed (m/s) in the 10 m walking test and change in Barthel index scores (range 0-100 points, higher scores indicating less disability) three months after stroke compared with baseline. Safety outcomes were recurrent cardiovascular events, including stroke, hospital readmissions, and death within three months after stroke. Efficacy was tested with analysis of covariance for each primary outcome in the full analysis set. Multiple imputation was used to account for missing values. RESULTS: Compared with relaxation, aerobic physical fitness training did not result in a significantly higher mean change in maximal walking speed (adjusted treatment effect 0.1 m/s (95% confidence interval 0.0 to 0.2 m/s), P=0.23) or mean change in Barthel index score (0 (-5 to 5), P=0.99) at three months after stroke. A higher rate of serious adverse events was observed in the aerobic group compared with relaxation group (incidence rate ratio 1.81, 95% confidence interval 0.97 to 3.36). CONCLUSIONS: Among moderately to severely affected adults with subacute stroke, aerobic bodyweight supported, treadmill based physical fitness training was not superior to relaxation sessions for maximal walking speed and Barthel index score but did suggest higher rates of adverse events. These results do not appear to support the use of aerobic bodyweight supported fitness training in people with subacute stroke to improve activities of daily living or maximal walking speed and should be considered in future guidelines. TRIAL REGISTRATION: ClinicalTrials.gov NCT01953549

An in-flight plasma diagnostic package for spacecraft with electric propulsion

The plasma diagnostics presented in this article target the plasma surrounding a spacecraft that is created by the electric thruster and its surface modifying effects. The diagnostic package includes a retarding potential analyzer, a plane Langmuir probe, and an erosion sensor. The paper describes the instrument as well as suitable test environments for mimicking the effects expected in space and shows test results. The system is to fly for the first time on the Heinrich Hertz satellite, which is scheduled to be launched in 2023. The spacecraft will be equipped with a pair of Highly Efficient Multistage Plasma Thrusters (HEMPT) and a pair of Hall thrusters for redundancy

Transcription factors relevant to auxin signalling coordinate broad-spectrum metabolic shifts including sulphur metabolism

A systems approach has previously been used to follow the response behaviour of Arabidopsis thaliana plants upon sulphur limitation. A response network was reconstructed from a time series of transcript and metabolite profiles, integrating complex metabolic and transcript data in order to investigate a potential causal relationship. The resulting scale-free network allowed potential transcriptional regulators of sulphur metabolism to be identified. Here, three sulphur-starvation responsive transcription factors, IAA13, IAA28, and ARF-2 (ARF1-Binding Protein), all of which are related to auxin signalling, were selected for further investigation. IAA28 overexpressing and knock-down lines showed no major morphological changes, whereas IAA13- and ARF1-BP-overexpressing plants grew more slowly than the wild type. Steady-state metabolite levels and expression of pathway-relevant genes were monitored under normal and sulphate-depleted conditions. For all lines, changes in transcript and metabolite levels were observed, yet none of these changes could exclusively be linked to sulphur stress. Instead, up- or down-regulation of the transcription factors caused metabolic changes which in turn affected sulphur metabolism. Auxin-relevant transcription factors are thus part of a complex response pattern to nutrient starvation that serve as coordinators of the metabolic shifts driving sulphur homeostasis rather then as direct effectors of the sulphate assimilation pathway. This study provides the first evidence ever presented that correlates auxin-related transcriptional regulators with primary plant metabolism