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Binäre Mesokristalle ermöglichen die Kombination von Nanokristalleigenschaften in einer geordneten Überstruktur. Hier zeigen wir die simultane Selbstanordnung von Platin- und Eisenoxid-Nanowürfeln zu μ-großen 3D-Mesokristallen mittels Gasphasendiffusion. Durch Zugabe geringer Mengen eines sekundären Partikeltyps, der auf nahezu identische Größe, Form und Oberflächenchemie zugeschnitten ist, erfolgte ein zufälliger Einbau von Fremdpartikeln in ein selbstorganisierendes Wirtgitter. Die zufällige Verteilung der binären Partikeltypen auf der Oberfläche und in ihrem Innern wurde mit Transmissions- und Rasterelektronenmikroskopie sichtbar gemacht. Die 20–40 μm großen binären Mesokristalle wurden mittels Weit- und Kleinwinkelstreuungstechniken genau charakterisiert, um eine Fernordnung auf atomarer Ebene im gesamten Kristall aufzuzeigen und Beweise dafür zu liefern, dass das Material aus einzelnen Bausteinen besteht. Durch Anpassung der Kristallisationsparameter ließ sich somit eine umgekehrte Überstruktur erzielen, bei der die inkorporierten Partikel und das Wirtgitter ihre Rollen tauschen. published

The paper presents the case of post-industrial space of the New Weaving Mill in Kilińskiego Street in Łódź, which was a part of Karol Scheibler’s empire. We use it to illustrate the tensions between actors of the city life and the related right to the city including the right to heritage. At the same time, we indicate the significance of involving different actors in the process of creating narratives (also those contributing to the extension of the research field) of it. In our discussion, we mostly perceive this space as everyday space – space of work that was marked with an unusual event: the visit of John Paul II in 1987. Thus, we consider the practices and strategies for commemorating/forgetting in the context of urban practices connected with the construction of heritage and the right to it. W artykule przybliżamy przypadek przestrzeni postindustrialnej Nowej Tkalni przy ul. Kilińskiego w Łodzi, będącej częścią dawnego imperium Karola Scheiblera, który posłuży nam do zaprezentowania napięć pomiędzy aktorami życia miejskiego i związanego z tym prawa do miasta, w tym także dziedzictwa. Jednocześnie wskażemy na istotności włączania różnorodnych aktorów w proces kształtowania narracji (również tych wpływających na rozszerzanie pola badawczego) o nim. W swoich rozważaniach wykorzystałyśmy przede wszystkim perspektywę spojrzenia na tę przestrzeń jako na przestrzeń codzienności – pracy, która została naznaczona wydarzeniem niecodziennym – wizytą Jana Pawła II w 1987 r. Zastanawiamy się więc nad praktykami i strategiami upamiętniającymi/zapominającymi w kontekście praktyk miejskich związanych z konstruowaniem dziedzictwa oraz prawa do niego.

Nach dem Drahtziehen treten hohe Zugeigenspannungen in den oberflächennahen Schichten des Drahtes auf. Dieser Eigenspannungszustand ist für die weitere umformtechnische Verarbeitung, z. B. für das Biegen zur Herstellung von Torsionstabfedern, ungeeignet. Nach derzeitigen Standards wird dem Drahtziehen eine Wärmebehandlung nachgeschaltet. In diesem Artikel wird ein neuer Ansatz zur Einstellung des Eigenspannungszustandes direkt im Umformprozess des Drahtes vorgestellt. Durch eine Modifikation der Ziehwerkzeuge mit integrierten Umformelementen sollen niedrigere Zugspannungsniveaus in den oberflächennahen Schichten des Drahtes erzeugt werden. Diese Elemente haben wesentlichen Einfluss auf den Grad der Kaltverfestigung, ohne den Drahtdurchmesser zu verändern. Zunächst werden mittels FE-Simulationen verschiedene Werkzeuggeometrien hinsichtlich ihrer Wirkung auf den Umformgrad sowie den Eigenspannungszustand des gezogenen Drahtes analysiert und bewertet. Durch den Einsatz eines speziell konzipierten Drahtziehwerkzeugs werden experimentelle Versuche durchgeführt und Drahtproben erzeugt. Weiterhin wird die Vorgehensweise für die Messung der Eigenspannungen durch den Einsatz von Röntgenbeugung erläutert. Für weiterführende experimentelle Untersuchungen zum Biegen erfolgte die Konzipierung eines modularen Werkzeuges, das eine Variation der Biegeradien und Drahtdurchmesser ermöglicht., After wire drawing high tensile residual stresses occur on the near-surface layers. This residual stress state is unsuitable for further forming processing, e.g. for bending to produce torsion bar springs. In precent industrial processes subsequent process steps, e.g. heat treatment are applied. In this study, a new approach and concept to adjust the residual stress state directly in the forming process of the wire is presented. Lower tensile stress levels in the near-surface layers of the wire shall be generated by modifying the drawing tools with integrated forming elements. These elements have a significant influence on the degree of work hardening without influencing the wire diameter. First, different die geometries are analysed and evaluated by means of FE simulations with regard to their effect on the plastic strain as well as the residual stress state of the drawn wire. By using a specially designed wire drawing tool, experimental tests are performed and wire samples are generated. Furthermore, the procedure for measuring residual stresses by using X‑ray diffraction is explained. For further experimental studies of bending, a modular tool was designed that enables the bending radii and wire diameters to be varied.

Eine effiziente Charakterisierung der Katalysatoren im Realraum und unter realistischen Bedingungen der elektrochemischen CO2‐Reduktion (CO2RR) gelang durch elektrochemische AFM. Die Entwicklung von Strukturmerkmalen konnte von der Mikrometer‐ bis hin zur atomaren Skala aufgelöst werden. Auf einer Cu(100)‐Modelloberfläche treten während der CO2RR in 0,1 m KHCO3 ausgeprägte nanoskalige Oberflächenmorphologien auf, wobei sich granulare Strukturen potentialabhängig in glatt geschwungene Berg‐und‐Tal‐Oberflächen oder rechteckige Terrassenstrukturen umwandeln. Mit stärker negativem Potential steigt die Dichte der unterkoordinierten Cu‐Zentren während der CO2RR. Durch atomar aufgelöste In‐situ‐Bildgebung wird bei bestimmten kathodischen Potentialen spezifische Adsorption nachgewiesen, die die Katalysatorstruktur beeinflusst. Die Ergebnisse verdeutlichen die komplexen Abhängigkeiten zwischen Morphologie, Struktur, Defektdichte, angelegtem Potential und Elektrolyt bei Kupfer‐CO2RR‐Katalysatoren.

Forschung im Ingenieurwesen = Engineering research (2021). doi:10.1007/s10010-021-00440-7, Published by Springer, Berlin ; Heidelberg

ZusammenfassungDer vorliegende Artikel analysiert die Chancen und Herausforderungen der Tokenisierung von Immobilien. Zunächst werden die theoretischen Grundlagen (Blockchain und Smart Contracts) sowie die Vor- und Nachteile der Tokenisierung diskutiert. Die Umsetzung der Tokenisierung einer Immobilie wird anschließend anhand eines Praxisbeispiels veranschaulicht. Die Vorteile einer Tokenisierung liegen in dem sofortigen weltweiten Handel der Token rund um die Uhr, dem Eigentumsübertrag der Token in „real time“, der Standardisierung bei gleichzeitiger Flexibilität, der Transparenz und Sicherheit im Handel der Token. Zudem ist die technische Umsetzung der Tokenisierung einer Immobilie sehr einfach. Regulatorische Unsicherheiten beschränken jedoch zurzeit noch eine breite Anwendung der Technologie.

The ability of cells to sense and respond to extracellular forces is critical for cellular and tissue homeostasis. Tension or compression act on our body ubiquitously and cells respond to such mechanical cues by producing intracellular forces on their own. In this article, we briefly highlight the cellular and physical basis driving these phenomena and discuss our recent technical advance to stimulate and monitor the cellular mechanoresponse on a molecular scale.

ZusammenfassungZiel dieser Arbeit ist die Einstellung eines vorteilhaften Druckeigenspannungsprofils in warmumgeformten Bauteilen durch intelligente Prozessführung mit angepasster Abkühlung aus der Schmiedewärme. Die Machbarkeit und das Potenzial werden an einem Warmumformprozess, bei dem zylindrische Proben mit exzentrischer Bohrung bei 1000 °C umgeformt und anschließend aus der Schmiedewärme im Wasser abgekühlt werden, aufgezeigt. Vorige Arbeiten zeigen, dass sich Zugeigenspannungen in den derartig umgeformten Proben aus dem Material 1.3505 einstellen. Mittels der vorgestellten mehrskaligen FE-Modelle, wird in dieser Arbeit eine alternative Prozessvariante analysiert, mit der vorteilhafte Druckeigenspannungen anstelle von Zugeigenspannungen durch eine angepasste Abkühlung aus der Umformwärme in den Proben erzeugt werden können. Die angepasste Kühlung wird durch eine partielle Beaufschlagung der Proben mit einem Wasser-Luft-Spray erreicht. Auf diese Weise kann die lokale Plastifizierung durch inhomogene Verzerrungen aufgrund thermischer und umwandlungsinduzierter Effekte beeinflusst werden, um letztlich das Eigenspannungsprofil individuell zu gestalten. Die wissenschaftliche Herausforderung dieser Arbeit besteht darin, unterschiedliche Eigenspannungen in der Oberfläche der Proben zu erzeugen, während die geometrischen und mikrostrukturellen Eigenschaften gleichbleiben. Es wird nachgewiesen, dass eine Beeinflussung der Eigenspannungen und sogar die Umkehr des Spannungsvorzeichens allein durch eine geschickte Prozessführung beim Abkühlen möglich ist.

ZusammenfassungDer enorme Stromverbrauch von Bitcoin hat dazu geführt, dass in Wissenschaft und Praxis oft eher undifferenziert Diskussionen über die Nachhaltigkeit von Blockchain- bzw. Distributed-Ledger-Technologie allgemein geführt werden. Allerdings ist die Blockchain-Technologie bereits heute alles andere als homogen – nicht nur hinsichtlich ihrer Anwendungen, die mittlerweile weit über Kryptowährungen hinaus in Wirtschaft und öffentlichen Sektor reichen, sondern auch bezüglich ihrer technischen Charakteristika und insbesondere ihres Stromverbrauchs. Dieser Beitrag fasst den Status quo des Stromverbrauchs verschiedener Implementierungen von Blockchain-Technologie zusammen und geht dabei besonders auf das kürzlich erfolgte Bitcoin Halving sowie sogenannte ZK-Rollups ein. Wir argumentieren, dass Bitcoin und andere Proof-of-Work-Blockchains zwar in der Tat sehr viel Strom verbrauchen, aber bereits heute alternative Blockchain-Lösungen mit deutlich geringerem Stromverbrauch verfügbar sind und weitere vielversprechende Konzepte erprobt werden, die gerade den Stromverbrauch von großen Blockchain-Netzwerken in naher Zukunft noch einmal deutlich senken könnten. Daraus schließen wir, dass die Kritik am Stromverbrauch von Bitcoin zwar legitim ist, jedoch daraus nicht eine Energieproblematik von Blockchain-Technologie generell abgeleitet werden darf. In vielen Fällen, in denen mithilfe von energieeffizienteren Blockchain-Varianten Prozesse digitalisiert oder verbessert werden können, darf sogar per Saldo durchaus mit Energieeinsparungen gerechnet werden.

Der vorliegende Beitrag befasst sich mit diskurs- und machtpolitisch hervorgerufenen Deutungshoheiten in Bezug auf Forschung zu und über Digitalisierung und Bildung in Programmatiken und Förderrichtlinien Deutschlands und der EU. Er gründet auf der Annahme, dass Forschungs- und Wissenschaftssysteme seit geraumer Zeit in enger Abhängigkeit zu Förderprogrammen stehen, welche auf unterschiedlichen politischen Ebenen als so genannte Förderinstrumente diverser Bildungsbereiche und der Wissenschaft selbst fungieren (sollen). Bei empirischer Betrachtung werden Deutungshoheiten infolge dieser Hinwendung zu und gleichzeitigen Abwendung von Begriffen und Konzepten sichtbar – nicht nur im Zusammenhang mit Diskursen um Digitalisierung und Bildung. Folge sind die (Über-)Betonung einzelner Konzepte und die zurückhaltende Repräsentation anderer, was für die Medienpädagogik qualifikatorische Engfassungen bedeutet, die auf empirischer Basis sowie vor dem Hintergrund präsenter Konzepte zu zeigen sind.

Durch das Auslaufen der EEG-Vergütung sowie der starken Einschnitte bei der Förderung der Biogasverstromung im novellierten EEG 2017 steht die Biogasbranche vor der Frage, welche Anschlusskonzepte sowohl wirtschaftlich attraktiv als auch langfristig aussichtsreich sein könnten. Die Kraftstoffproduktion aus Biogas wäre eines der möglichen Anschlussszenarien. In mehreren Studien wird bis 2050 eine Verschiebung der Biogasverwertung von der Verstromung hin zur Kraftstoffnutzung prognostiziert. Auch die Politik strebt eine höhere Umsetzung von Bioenergie im Kraftstoffsektor an. In diesem Beitrag werden daher Anschlussszenarien mit Strom- und Kraftstoffproduktion in Biogasanlagen ökonomisch bewertet. Außerdem wird ein neuer Flexibilisierungsansatz mit anteiliger Strom- und Kraftstofferzeugung von jeweils 50 % an der Biogasverwertung untersucht. Mithilfe von flexibilisierten Verstromungsfahrplänen, lokalen Daten zum Kraftstoffbedarf von Fuhrparks und eines darauf basierenden Kraftstoff­erzeugungsfahrplans wurde der erforderliche Biogasspeichermehrbedarf, der Hochdruckspeicherbedarf sowie die notwendige Anlagenleistung für die Kraftstoffproduktion ermittelt. Schließlich wurden mehrere Anschlussszenarien für eine repräsentative Modellbiogas­anlage nach der Kapitalwertmethode ökonomisch bewertet. Beim Vergleich zeigte sich, dass die Anschlussszenarien mit Kraftstoffproduktion wirtschaftlicher sind als jene mit ausschließlicher Stromproduktion. Je nachdem, wie die geplante nationale Umsetzung der Neufassung der europäischen Erneuerbare-Energien-Richtlinie (RED II) realisiert wird, kann sich die Wirtschaftlichkeit – insbesondere bei der Erhöhung des Gülleanteils in der Substratzusammensetzung – deutlich verbessern., LANDTECHNIK, Bd. 75 Nr. 3 (2020)

Es wird eine universelle, auf Nanokapillaren basierende Methode zur Probenabscheidung auf der Siliziumnitridmembran von LCTEM-Chips (liquid cell transmission electron microscopy) vorgeschlagen. Sie ist auf alle Substanzen anwendbar, die in einem Lösungsmittel dispergierbar und für eine Tropfenimmobilisierung geeignet sind, einschließlich Katalysatoren, biologische Proben und Polymere. Am wichtigsten ist, dass diese Methode die Einschränkungen bezüglich der Probenimmobilisierung aufgrund der Zerbrechlichkeit der ultradünnen Glaskohlenstoffelektrode/Siliziumnitridmembran, die für die Elektronenübertragung erforderlich ist, überwindet. Somit wird ein einfacher Weg vorgestellt, um das Forschungsgebiet des LCTEM auf jede Probe zu erweitern, die zuvor extern abgeschieden werden kann. Mit dieser Methode werden NixB-Nanopartikel auf der Arbeitselektrode des LCTEM-Chips im mm-Maßstab deponiert und die In-situ- Beobachtung einzelner Katalysatorpartikel während der Ethanoloxidation erstmals erfolgreich mithilfe von TEM-Filmen durchgeführt.

Soiling is a challenge for both concentrating solar and photovoltaic technologies. Measurement procedures and efficiency sensitivities to soiling for the same surface particle density differ due to the different optical characteristics of both technologies. For this reason, soiling investigations performed at a site for one technology are not necessarily applicable to the other technology. Soiling measurements have been performed mostly under fixed or rarely occurring angles of incidence. In this study parallel measurements of soiling loss and particle mass density found on the main optical surfaces of concentrating solar power (CSP) and photovoltaic (PV) technologies are presented. The measurements are taken on samples of CSP second surface mirror and PV solar glass with consideration of the main optical characteristics of both technologies. Optical soiling losses are found to be higher by a factor of 8–14 in CSP for the same particle surface densities compared to PV. A Mie-based model is presented and validated, that converts the particle mass density and a set of other inputs into the optical soiling loss for either technology for normal angle of incidence and varying angles of incidence. This method facilitates the transfer of soiling loss data from one technology to another. The method can significantly increase the knowledge on soiling for both technologies as more measurement data is made accessible. Additionally, the soiling losses for different angles of incidence can be used to estimate more realistic annual loss parameters for the technologies in question and give recommendations for optimized incidence angles to be used in soiling measurements for both technologies.

Leseprobe ----- Zusammenfassung Der Modellversuch „Nachhaltigkeit in den Lebensmittelberufen (NachLeben)“ entwickelt und erprobt situierte betriebliche Lehr-Lernarrangements zur Forderung der Bewertungs-, Gestaltungs- und Systemkompetenz fur Ausbildungsberufe in der Lebensmittelindustrie und im Lebensmittelhandwerk. Ein Beispiel ist das Lehr-Lernarrangement „Kunststoffe im Produktionsprozess“, welches den Fokus des Artikels bildet. Schlusselworter: Nachhaltigkeit, Berufsausbildung, Gestaltungskompetenz, Lehr-Lernarrangements, Situiertes Lernen ----- Situated teaching-learning arrangements for the promotion of sustainability competencies in the in-company training of food professions Abstract The pilot project “Sustainability in the food professions (NachLeben)” develops and tests situated in-company teaching-learning arrangements to promote assessment, design, and system competence for training occupations in the food industry and the food trade. One example is the teaching-learning arrangement “Plastics in the production process”, which is the focus of the article. Keywords: sustainability, vocational training, design competence, teaching-learning arrangements, situated learning ----- Bibliographie: Vieback, Linda/Bramer, Stefan/Hagendorf, Tom/Folkens, Lukas/Herzog, Michael A./Bunning, Frank: Situierte Lehr-Lernarrangements zur Forderung von Nachhaltigkeitskompetenzen in der betrieblichen Ausbildung von Lebensmittelberufen, HiBiFo – Haushalt in Bildung & Forschung, 3-2020, S. 48-64. https://doi.org/10.3224/hibifo.v9i3.04

Zusammenfassung Ethen (Ethylen, C 2 H 4 {\text{C}_{2}}{\text{H}_{4}} ) ist eines der wichtigsten Phytohormone im Reifungsprozess klimakterischer Früchte. Die Menge des emittierten Ethens liefert Informationen über den aktuellen Reifezustand dieser Früchte. Deshalb können Ethensensoren in der Lieferkette für die Umsetzung fortschrittlicher Logistik-Prozesse wie dem First-Expired-First-Out-Prozess (FEFO) eingesetzt werden. Diese Arbeit beschreibt den aktuellen Stand der Entwicklung eines kostengünstigen Filterrotationsspektrometers für den Nachweis von Ethen in der klimakterischen Reifephase von Früchten. Das Spektrometer basiert im Wesentlichen auf Komponenten, die auch in nichtdispersiven Infrarotsensoren (NDIR) zum Einsatz kommen. Durch eine modellbasierte Auswertung der gemessenen Spektren konnte die Stabilität eines ersten Laborprototyps gegenüber klassischen NDIR-Sensoren deutlich verbessert werden. In Verbindung mit einer optimierten Langwegzelle wurde eine Nachweisgrenze von 150 ppb erreicht. Simulationen haben außerdem gezeigt, dass sich dieses Prinzip auch für die quantitative Bestimmung potentieller Querempfindlichkeitsgase wie Ammoniak ( NH 3 {\text{NH}_{3}} ) und Kohlenstoffdioxid ( CO 2 {\text{CO}_{2}} ) eignet. Durch Verknüpfung der Simulations- und Messergebnisse wird eine Nachweisgrenze von 0,19 % für CO 2 {\text{CO}_{2}} und 62 ppb für NH 3 {\text{NH}_{3}} erwartet.

The visual system is one of the most important human senses. Hence, blindness leads to an unimaginable reduction of life quality. However, most diseases leading to the loss of vision are still incurable, because current models used in ophthalmic research fail to recapitulate the human eye in many crucial aspects. Combining human retinal organoids with Organ-on-a-chip technology may lead to a paradigm shift in the way we study pathogenesis and treatment of retinal diseases.

Ausgehend vom Stellenwert digitaler Medien und sozialer Netzwerke im Alltag junger Menschen werden in diesem Beitrag fachwissenschaftliche Zugänge aus den Citizenship Studies mit lerntheoretischen Überlegungen zum Bürgerbewusstsein verbunden. Hervorgehoben wird dabei das Verhältnis von digitaler Erfahrungs- und analoger Reflexionswelt für die Entwicklung des individuellen Bürgerbewusstseins. Abschließend werden daraus Konsequenzen für politische Lernprozesse in der digitalisierten Welt abgeleitet. (DIPF/Orig.), Based on the importance of digital media and social networks in the everyday life of young people, this paper combines approaches from citizenship studies with learning theory approaches on citizen awareness. The relationship between digital experiences and its analogue reflections for the development of individual citizenship awareness is emphasized. Finally, consequences for political learning processes in the digitized world are deduced. (DIPF/Orig.)

Die Autorin skizziert die Bedeutung der Lehrkräftebildung für die Organisation von Universitäten und appelliert an die integrierende Funktion der Erziehungswissenschaft für eine kohärente Lehrkräftebildung. (DIPF/Orig.)

We present a robust, compact pulse synthesis scheme generating intense phase-locked subcycle multi-terahertz waveforms. The ultrabroadband laser fundamental is split into two parallel branches driving optical rectification in crystals of GaSe and LiGaS2, each operated at the group velocity matching point. The coherent combination of the resulting pulses yields a continuous multi-terahertz spectrum covering 1.5 optical octaves. The corresponding 0.8-cycle electric field waveform is directly mapped out by electro-optic sampling, revealing peak fields of 15 kV/cm at a repetition rate of 0.4 MHz. The multiplexable and power scalable scheme opens the door to strong-field custom-tailored waveforms driving nonlinear optics and light wave electronics. (C) 2019 Optical Society of America

Undoped and Co-doped TiO2 nanoparticles were synthesized by a facile co-precipitation method and calcined at 700°C. The phase identification carried out by XRD measurements and Raman spectroscopy analysis of calcined powders reveals the formation of mainly anatase phase for undoped TiO2, and 0.5 mol % Co-doped TiO2 whereas rutile phase for 1 mol % Co-doped TiO2. The sensors prepared with these powders deposited on interdigital (IDE) sensor platforms were tested toward NO2 and H2 sensing properties at 600 °C. As the undoped and 0.5 % Co-doped TiO2 reveal n-type behavior, 1 % Co-doped TiO2 shows p-type semi-conductive behavior. 1 % Co-doped TiO2 exhibits good sensing performance toward NO2 while the undoped TiO2 powder yields the best sensor performance toward H2 at 600°C. This indicates that the crystal structure of TiO2 sensing material must be adjusted depending on the nature of target gas. The results indicate that the main factor influencing high temperature gas sensor performance of nanoparticulate TiO2 is either the alteration of its electronic structure or the type of polymorphs.

Damage-tolerant ceramic matrix composites (CMC) are prone to high temperature applications under severe environmental conditions and usually utilize carbon or ceramic fibres (e.g. SiC) as reinforcements of ceramic matrices with inherent low elongation to break compared to common metals. However, CMC reveal an elongation to break and stiffness similar to the ceramic matrices, and thus need a fibre coating in order to improve the elongation to break length and thus to achieve damage tolerance of the composite. In addition, such fibers often expose a low ductility during failure. As a consequence, design criteria for components of such CMC materials are limited by the low strain of failure. In order to overcome this problem, we follow the idea of a reinforcement concept of a ceramic matrix reinforced by refractory metal fibres to reach pseudo ductile behaviour during failure. Tungsten (W) and molybdenum (Mo) fibers were chosen as reinforcement in SiCN CMC manufactured by polymer infiltration and pyrolysis process. These fibres are commercially available since they are widespread used in light bulbs, etc. , and possess an intrinsic higher elongation to break, compared to ceramic fibres, as well as high stiffness even at high temperatures. W/SiCN and Mo/SiCN composites were manufactured via filament winding and resin transfer moulding of commercially available polysilazanes, pyrolysed and re-densified by multiple reinfiltration and pyrolysis steps. These composites were investigated with respect to microstructure, flexural and tensile strength. Single fibre strengths for W and Mo were investigated and compared to the strength of the composites. Tensile strengths of 206 and 156 MPa as well as bending strengths of 427 and 312 MPa were achieved for W/SiCN and Mo/SiCN composites, respectively. W fibre became brittle across the entire cross section, while the Mo fibre showed a superficial, brittle reaction zone but kept ductile on the inside.

For quasi-freestanding 2H-TaS2 in monolayer thickness grown by in situ molecular beam epitaxy on graphene on Ir(111), we find unambiguous evidence for a charge density wave close to a 3 × 3 periodicity. Using scanning tunneling spectroscopy, we determine the magnitude of the partial charge density wave gap. Angle-resolved photoemission spectroscopy, complemented by scanning tunneling spectroscopy for the unoccupied states, makes a tight-binding fit for the band structure of the TaS2 monolayer possible. As hybridization with substrate bands is absent, the fit yields a precise value for the doping of the TaS2 layer. Additional Li doping shifts the charge density wave to a 2 × 2 periodicity. Unexpectedly, the bilayer of TaS2 also displays a disordered 2 × 2 charge density wave. Calculations of the phonon dispersions based on a combination of density-functional theory, density-functional perturbation theory, and many-body perturbation theory enable us to provide phase diagrams for the TaS2 charge density wave as functions of doping, hybridization, and interlayer potentials, and offer insight into how they affect lattice dynamics and stability. Our theoretical considerations are consistent with the experimental work presented and shed light on previous experimental and theoretical investigations of related systems.

The paper focuses on medieval wooden sculptures in the 12th and early 13th century in Norway, with preserved original polychromy. The presentation of materials used in the construction, the painting and gilding are based on material analyses. Their application is discussed and compared to those produced in the period that immediately follows. Conclusions reached about the characteristics of this period allow future research to be suggested. It is clear from the evidence gained that both the making and the perception of Catholic church art in medieval Norway was firmly rooted in an established culture consistent with Christian paradigms found in the rest of medieval Europe. The analytical results from the examination of sculpture preserved in Norway are therefore relevant to a wider European context. To what extent medieval sculpture was imported or produced in Norway and by whom is an ongoing discussion. A better knowledge of the sculptural traditions of a wider geographical area will provide the context required to improve our understanding of the cultural exchanges of the medieval period. O artigo foca-se em esculturas medievais de madeira dos séculos XII e XIII na Noruega, com policromia original preservada. A apresentação de materiais usados na construção, na pintura e na douradura baseiam-se na análise de materiais. A sua aplicação é discutida e comparada com casos do período imediatamente a seguir. As conclusões alcançadas relativamente às características deste período permitem a sugestão de investigação futura. Fica claro, a partir das evidências obtidas, que tanto a forma de fazer como a forma de percepcionar a arte da Igreja Católica na Noruega medieval estava firmemente enraizada numa cultura estabelecida que era consistente com os paradigmas cristãos encontrados no resto da Europa medieval. Os resultados analíticos do exame da escultura preservada na Noruega são, portanto, relevantes para um contexto europeu mais vasto. Até que ponto a escultura medieval foi importada para ou produzida na Noruega e por quem é uma discussão em aberto. Conhecer melhor as tradições escultóricas de uma área geográfica mais abrangente providenciará o contexto necessário para aperfeiçoarmos o entendimento que temos das trocas culturais do período medieval.

BioNanoMaterials, 17 (3-4), ISSN:2193-066X, ISSN:2193-0651

Terahertz (THz) quantum-cascade lasers (QCLs) are narrow band, high-power, and frequency-agile sources. These properties make them attractive for applications in high-resolution molecular and atomic spectroscopy. In the past few years, various techniques and methods regarding high-resolution spectroscopy with THz QCLs have been developed, namely, direct absorption spectroscopy, detection schemes such as wavelength and frequency modulation, differential spectroscopy, photoacoustic spectroscopy, and heterodyne spectroscopy. We briefly review the most relevant technological and methodological advances in this field, and we discuss perspectives and future directions.

We report a novel cavity feedback mechanism for stabilizing single-longitudinal-mode (SLM) operation of diamond Raman lasers. Polarization-dependent Raman gain and in-grown stress birefringence in diamond were investigated as sources for Hansch-Couillaud-type locking signals. The power range of SLM operation increased from 2.1 W to 7.2 W, compared to the free-running laser, for a simple standing-wave laser cavity without frequency-selective elements. Methods for further increasing power range and frequency stability are discussed.

A low pressure impactor is used to measure the mechanical stability of nanoparticle agglomerates. The stability at different impaction velocities is quantified as changes in the projection area of agglomerate fragments deposited on TEM grids mounted on the impaction plate. Platinum particles produced in a spark discharge generator are used as model particles. The mechanical stability of unmodified Pt-agglomerates is compared with the ones of thermally pretreated and coated agglomerates. The coatings are produced in a plasma assisted chemical vapor deposition process using the post-discharge environment of a dielectric barrier discharge. The coating process allows the coating of particles with silica at ambient temperature and so minimizes structural changes of the agglomerates before impaction. The precursors utilized are tetraethyl orthosilicate for silica and hexamethyldisiloxane for silica-organic coatings. Both coatings improve the stability of the agglomerates as indicated by reduced structural changes during impaction. The silica-organic coating, which is applied at 200 °C, seems to prevent sinter-related changes to the particles, which is observed for the uncoated particles at this temperature. This is further corroborated by the deposition behavior of these coated particles, which resembles more that of the original particles at 24 °C. Furthermore, the rebound behavior of coated agglomerates impacting on the TEM grid is shown. It is found that a minority of the particles rebound back from the TEM grid into the gas, which occurs in parallel to the structural changes.

International audience

While a government commission recently proposed to phase out coal in Germany by 2038, voters would prefer a phase-out by 2025. Policymakers may underestimate public willingness to support an expedited transition away from high-carbon sources of energy.

Schulleitungen sind heutzutage weitaus mehr als Lehrkräfte mit zusätzlichen Verwaltungsaufgaben. Es wird von ihnen erwartet, Verantwortung in den Bereichen Management, Führung, Verwaltung und Personalentwicklung zu übernehmen, dabei jedoch auch weiterhin Lehrkräfte sowie Verwaltende zu sein. Doch existieren für diese zusätzlichen Tätigkeitsbereiche entsprechende Qualifizierungsmaßnahmen? In welcher Form und Verbindlichkeit findet in Deutschland eine Qualifizierung zur Schulleitung statt? Inwiefern unterscheidet sich eine Qualifizierung von Bundesland zu Bundesland? Diesen Aspekten geht dieser Beitrag auf Basis einer deutschlandweiten Analyse der maßgeblichen Gesetze, Vorschriften und Regularien nach. (DIPF/Orig.), School leaders in Germany are a lot more than teachers with additional administrative tasks. They are expected to be managers, school developers, leaders, and in addition also administrators and teachers. How are they qualified for this position? What forms of qualification exist and how obligatory are they? How does this differ between the Federal States of Germany? This is analyzed in this contribution, based on an analysis of the relevant legal instructions and regulations. (DIPF/Orig.)

Here, amorphous silica nanoparticles (NPs), one of the most abundant nanomaterials, are used as an example to illustrate the utmost importance of surface coverage by functional groups which critically determines biocompatibility. Silica NPs are functionalized with increasing amounts of amino groups, and the number of surface exposed groups is quantified and characterized by detailed NMR and fluorescamine binding studies. Subsequent biocompatibility studies in the absence of serum demonstrate that, irrespective of surface modification, both plain and amine-modified silica NPs trigger cell death in RAW 264.7 macrophages. The in vitro results can be confirmed in vivo and are predictive for the inflammatory potential in murine lungs. In the presence of serum proteins, on the other hand, a replacement of only 10% of surface-active silanol groups by amines is sufficient to suppress cytotoxicity, emphasizing the relevance of exposure conditions. Mechanistic investigations identify a key role of lysosomal injury for cytotoxicity only in the presence, but not in the absence, of serum proteins. In conclusion, this work shows the critical need to rigorously characterize the surface coverage of NPs by their constituent functional groups, as well as the impact of serum, to reliably establish quantitative nanostructure activity relationships and develop safe nanomaterials.

Model-based reconstruction techniques have been successfully implemented in optoacoustic tomography and acoustic-resolution microscopy to retrieve improved image quality over delay-and-sum methods. In scanning optical resolution optoacoustic microscopy (OR-OAM), no reconstruction methods are employed while post- processing is usually limited to basic frequency filtering and envelope extraction with the Hilbert transform. This results in considerable deterioration of the acoustically-determined resolution in the axial (depth) direction. In addition, when OR-OAM is used for transcranial mouse brain imaging, the skull strongly attenuates high ultrasonic frequencies and induces reverberations, which need to be accounted for during the reconstruction process to avoid image distortions and further deterioration of the axial resolution. Here we show a basic implementation of a model-based reconstruction to increase the axial resolution in OR-OAM. The model matrix is calculated using Field II for free field conditions, taking into account the shape and bandwidth of the spherically focused transducer. Assuming the confinement of the optoacoustic sources within the limits of the optical focus, one may calculate the model matrix by assuming a line source of small absorbing spheres equal in size to the optical beam. In addition, a plate model used in the recently reported virtual-craniotomy deconvolution algorithm is incorporated into the model matrix to tackle the transcranial acoustic transmission problem. The free-field model-based results are compared against the plate model for transcranial brain data obtained in-vivo.

Aging promotes lung function decline and susceptibility to chronic lung diseases, which are the third leading cause of death worldwide. Here, we use single cell transcriptomics and mass spectrometry-based proteomics to quantify changes in cellular activity states across 30 cell types and chart the lung proteome of young and old mice. We show that aging leads to increased transcriptional noise, indicating deregulated epigenetic control. We observe cell type-specific effects of aging, uncovering increased cholesterol biosynthesis in type-2 pneumocytes and lipofibroblasts and altered relative frequency of airway epithelial cells as hallmarks of lung aging. Proteomic profiling reveals extracellular matrix remodeling in old mice, including increased collagen IV and XVI and decreased Fraser syndrome complex proteins and collagen XIV. Computational integration of the aging proteome with the single cell transcriptomes predicts the cellular source of regulated proteins and creates an unbiased reference map of the aging lung., Aging impacts lung functionality and makes it more susceptible to chronic diseases. Combining proteomics and single cell transcriptomics, the authors chart molecular and cellular changes in the aging mouse lung, discover aging hallmarks, and predict the cellular sources of regulated proteins.

In this work, we discuss the effect of multiphase flow dynamics on the performance of a PEM electrolyzer. We obtained images of a flow system consisting of O2 and water at two stages of gas production: gas evolution via bubbles and gas exiting through the channels of a flow field. We processed the obtained images of bubble evolution with a MATLAB-based bubble detection and counting algorithm, and we found that the bubble detachment sizes remained invariant within a water flow range between 0.07 and 4.65 l h−1. We measured an average bubble detachment radius of 22.47 μm. We applied a bubble force balance developed by van Helden et al. [1] to model the observed effect of water flow on bubble evolution, and we found that the bubble detachment radius is a weak function of water flow when the water flow is below 60 l h−1. We found that the variables that affect the bubble detachment radius the strongest were the electrode's hydrophobicity and pore size.

Der Beitrag präsentiert quantitative und qualitative Befunde zur interprofessionellen Kooperation von Lehrkräften und pädagogischem Personal in Bezug auf Förderangebote an Ganztagsgrundschulen. Die Ergebnisse zeigen eine geringe Zusammenarbeit, die sich vornehmlich auf den Schüleraustausch beschränkt. Komplexere Formen der Zusammenarbeit finden sich lediglich in Bezug auf Kinder mit sonderpädagogischem Förderbedarf. (DIPF/Orig.), This paper presents results of a quantitative and qualitative study examining the co-operation of teachers and pedagogical staff concerning individual fostering of students. The results show a low level of cooperation between the groups, which is mainly limited to the direct exchange about individual students. Higher levels of cooperation are only found with regard to children with special educational needs. (DIPF/Orig.)

Der Diskurs über gemeinsame Ziele der Lehrerbildung in Deutschland ist spätestens durch die Qualitätsoffensive Lehrerbildung virulent und provoziert notwendigerweise Auseinandersetzungen um Deutungshoheit. Der Beitrag dokumentiert die Prozesse zweier Universitätsstandorte (Bielefeld und Duisburg-Essen), die sich auf den Weg gemacht haben, unnötigen Implementationshürden monoparadigmatischer Vereinseitigungen das Programm einer multiparadigmatischen Lehrerbildung entgegenzustellen. Es wird eine Heuristik präsentiert für weitere theoretisch-systematische Arbeit an einer gegenstandsorientierten Meta-Theoriebildung. Trotz der Hyperkomplexität des Anspruchs einer "kohärenten Theorie und Praxis der multiparadigmatischen Lehrerbildung" soll an ihr als regulativer Idee festgehalten werden, da dies angesichts der Risiken monoparadigmatischer Verengungen und hoher Transaktionskosten durch unproduktive Auseinandersetzungen um Deutungshoheit aus Sicht der Autor*innen alternativlos erscheint. (DIPF/Orig.), The discourse on common goals of teacher training in Germany has been particularly virulent since the "Qualitätsoffensive Lehrerbildung" (Quality Offensive in Teacher Training) and necessarily provoked systematic disputes about the sovereignty of interpretation. The article documents the processes of two university locations (Bielefeld and Duisburg-Essen), which have set out to counter unnecessary implementation hurdles of monoparadigmatic one-sidedness by the program of multiparadigmatic teacher education. The authors present a heuristic for further theoretical-systematic work on an object-oriented meta-theory formation. Despite the hyper-complexity of the claim of a "coherent theory and practice of multiparadigmatic teacher education," it is supposed to serve as a regulative idea. Given the risks of monoparadigmatic constrictions and high transaction costs due to unproductive conflicts over interpretive sovereignty, this seems to be without alternative from the perspective of the authors. (DIPF/Orig.)

The demand for accurate solar irradiance nowcast increases together with the rapidly growing share of solar energy within our electricity grids. Intra-hour variabilities, mainly caused by clouds, have a significant impact on solar power plant dispatch and thus on electricity grids. All sky imager (ASI) based nowcasting systems, with a high temporal and spatial resolution, can provide irradiance nowcasts that can help to optimize CSP plant operation, solar power plant dispatch and grid operation. The radiative effect of clouds is highly variable and depends on micro- and macrophysical cloud properties. Frequently, nowcasting systems have to measure/estimate the radiative effect during complex multi-layer conditions with strong variations of the optical properties between individual clouds. We present a novel approach determining cloud transmittance from measurements or from correlations of transmittance with cloud height information. The cloud transmittance is measured by a pyrheliometer when shaded, as the ratio of shaded direct normal irradiance (DNI) and clear sky DNI. However, for most clouds, direct transmittance measurements are not available, as these clouds are not shading the used pyrheliometers. These clouds receive an estimated transmittance value based on (1) their height, (2) results of a probability analysis with historical cloud height and transmittance measurements as well as (3) recent transmittance measurements and their corresponding cloud height. Cloud heights are measured by a stereoscopic approach utilizing two ASIs. We discuss site dependencies of the presented transmittance estimation method and the potential integration of automatic cloud classification approaches. We validated the cloud transmittance estimation over two years (2016 and 2017) and compare the probabilistic cloud transmittance estimation approach with four simple approaches. The overall mean-absolute deviation (MAD) and root-mean-square deviation (RMSD) are 0.11 and 0.16 respectively for transmittance. The deviations are significantly lower for optically thick or thin clouds and larger for clouds with moderate transmittance between 0.18 and 0.585. Furthermore we validated the overall DNI forecast quality of the entire nowcasting system, using this transmittance estimation method, over the same data set with three spatially distributed pyrheliometers. Overall deviations of 13% and 21% are reached for the relative MAD and RMSD with a lead time of 10 min. The effects of the chosen data set on the validation results are demonstrated by means of the skill score.

Summary The increasing population and large scale growth with the development of modern science and technology has indicated very high stress on water sector in Rajasthan in India. Availability of water and uniformity of rainfall distribution is changing day by day due to shifting of monsoon in Rajasthan. The spatial and temporal variations in the rainfall in different river basins in Rajasthan are drastic due to which flood situation arises in the tributaries of Chambal river basin every year. Simultaneously on the other hand drought situation arises in the other different places in the most of the river basins which are also under dark zone. In totality natural water resources are also limited in Rajasthan so there is an urgent need for its proper planning, development and management of the available water duly taking care of environmental, ecological, socio-economic aspects and their inter-relationships. Annual surplus water of about 1437 MCM in the river Chambal is going waste and ultimately reaches to sea after creating flood situations in various places in India including Rajasthan, while on the other hand 1077 MCM water is a requirement in the four other basins in Rajasthan i.e. Banas, Banganga, Gambhir and Parbati at 75% dependability. Interlinking and water transfer from Chambal to these four river basins is the prime solution for which 372 km link channel including 9 km tunnel of design capacity of 300 cumec with 64 m lift is required.

Summary In the present study, the microstructure and mechanical properties of similar and dissimilar friction stir welded joints of aluminium alloy (AlA) and pure copper (Cu) were evaluated at variable tool rotational speeds from 150 to 900 rpm in steps of 150 rpm at 60 mm/min travel speed and constant tilt angle 2°. The interfacial microstructures of the joints were characterised by optical and scanning electron microscopy. The Al 4 Cu 9 , AlCu, Al 2 Cu and Al 2 Cu 3 intermetallic compounds have been observed at the interface and stir zone region of dissimilar Al/Cu FSWed joints. Variation in the grain size was observed in the stir zone depending upon the heat input value. Axial force, traverse force and torque value were analysed with variation in tool rotational speed. Residual stresses were measured at the stir zone by X-ray diffraction technique. Maximum ultimate tensile strength of ∼75% of AlA strength for AlA–AlA joints has been obtained at 750 rpm and for Cu–Cu joint tensile strength of ∼100% of tensile strength of Cu was obtained at 300 rpm. However, for Cu–AlA joint when processed at 600 rpm tool rotational speed achieved maximum ultimate tensile strength of ∼77% of AlA.

Summary Alarming situation of toxic substances such as benzene and its analogs in the environment and workplaces, making it important to monitor these chemicals and their metabolites in order to evaluate risk hazards and potential problems caused by exposure to toxic compounds. Benzene is omnipresent in usage across industries. International Agency for Research on Cancer (IARC) which is a part of World Health Organization (WHO) has classified Benzene as a human carcinogen. trans-trans Muconic acid (ttMA) is the most important biomarker of benzene for biomonitoring of its low level exposure. In this paper the sensing ability of polyaniline (PANI) to ttMA is investigated for development of cheap, portable and effective electrochemical biosensor. To take this ahead for biosensor device application, successful self-assembling of PANI nanofibers of 40–70 nm range on SS 304 working electrode was achieved. Fourier transform infrared spectroscopy and X-ray diffraction was used to characterize the chemical structure of PANI. Morphology of sample was observed by field emission gun scanning electron microscopy (FEG-SEM). The detection potential of ttMA in phosphate buffer solution of pH 5.8 acting as a supporting electrolyte was found to be at 0.26 V by linear sweep voltammetry.

Summary This paper focuses on corrosion characteristics of cast and forged aluminium 6061 based composites reinforced with TiB 2 particles. Composites were synthesised by in situ technique using potassium hexafluorotitanate salt (K 2 TiF 6 ) and potassium tetrafluroborate (KBF 4 ) halide salts by stir casting route at a temperature of 850 °C. Cast aluminium alloy and its in situ composites were subjected to open die drop forging at a temperature of 500 °C. Both cast and forged alloy 6061 and in situ composites were then subjected to microstructure studies, salt spray test. Salt spray test was conducted as per ASTM B117 standard test procedure using 5% sodium chloride test solution. Result reveals that, forged alloy and its in situ composites exhibited improved corrosion resistance compared to cast ones.

Summary The friction at the piston ring cylinder liner assembly (PRLA) is a major contributor in the total friction losses in the I.C. engine. New materials, coatings and high-tech machining processes that previously were considered to be too expensive and therefore only used in complex applications are today becoming more affordable. A significant amount of the total power loss in a modern automotive engine is due to the Friction interaction between the top compression ring and the cylinder liner, especially at the TDC and BDC where boundary lubrication exists. The change in piston speed is accompanied with change the lubrication regime in the cylinder, which results change in friction between the ring and the liner during the entire stroke of the piston. Theoretical modelling of friction force from the various sources of friction will be compared to experimental results for analysing the tribological characteristics. The appropriate sample of piston ring and cylinder liner pair is developed for studying the different tribological parameters on Reciprocating Tribometer. The variable parameters are engine speed, oil viscosity, and load. The experimental results and observations are studied under different operating conditions in speed ranges from 300 rpm to 1500 rpm with constant load of 60 N. It can be seen that as speed increases, the friction force and friction coefficient also decreases.

Summary Emergence of silt conscious designs of hydro power plants is an great challenge which calls for pooling the experiences of concerned. It also under lines the desirability of silt consciousness during investigations, design, operation, maintenance, refurbishment and upgrading. Due to inherent weak geology, rock instability, population explosions and deforestation, all rivers emanating from Himalayas carry enormous quantity of silt during heavy runoff of monsoon from June to September. Hydro Power stations located in Himalayan region face heavy silt problems during high inflow periods. Siul River carries heavy silt concentration of the order of 30,000 PPM (Part Per Million) (4) affecting generation, eroding turbines and cooling water system, requiring heavy cost towards maintenance of Baira Siul project. Similarly Chenab River on which Salal Project is located also carries enormous quantity of silt affecting shut down, damage to glacis to the tune of 15 cm to 20 cm, and severe damages to turbines and cooling water system of the project. Remedial measures have been taken like replacing the metallurgy of stainless steel for runner, guide vanes by 13 Cr Ni4 and hydro siphoning from the reservoir to maintain the generation. A series of other experiments were also tried on these projects by using modern technology. Some of them are successful to some extent.

Summary A cellular neural network (CNN) is a massively parallel analog array processor capable of solving various complex processing problems by using specific templates that characterize the synaptic connections. The hardware implementation and applications of CNN have attracted a great deal of attention. Recently, memristors with nanometer-scale and variable gradual conductance have been exploited to make compact and programmable electric synapses. This paper proposes and studies a novel memristive CNN (Mt-CNN) with time-variant templates realized by memristor crossbar synaptic circuits. The template parameters are estimated analytically. The Mt-CNN provides a promising solution to hardware realization of real-time template updating processes, which can be used to effectively deal with various complicated problems of cascaded processing. Its effectiveness and advantages are demonstrated by practical examples of edge detection on noisy images.

ISSN:1521-3757 ISSN:0044-8249

We report on circuit simulation, modeling, and characterization of field-effect transistor based terahertz (THz) detectors (TeraFETs) with integrated patch antennas for discrete frequencies from 1.3 to 5.7 THz. The devices have been fabricated using a standard 90-nm CMOS technology. Here, we focus in particular on a device showing the highest sensitivity to 4.75-THz radiation and its prospect to be employed for power monitoring of a THz quantum cascade laser used in a heterodyne spectrometer GREAT (German REceiver for Astronomy at Terahertz frequencies). We show that a distributed transmission line based detector model can predict the detector's performance better than a device model provided by the manufacturer. The integrated patch antenna of the TeraFET designed for 4.75 THz has an area of $13\times 13$ $\mathrm{\mu }$ m $^2$ and a distance of 2.2 $\mu$ m to the ground plane. The modeled radiation efficiency at the target frequency is 76% with a maximum directivity of 5.5, resulting in an effective area of 1750 $\mu$ m $^2$ . The detector exhibits an area-normalized minimal noise-equivalent power of 404 pW/ $\sqrt{\mathrm{Hz}}$ and a maximum responsivity of 75 V/W. These values represent the state of the art for electronic detectors operating at room-temperature and in this frequency range.

Triplet–triplet annihilation photon upconversion (TTA-UC) is a photophysical process in which the energy of two photons are combined into a single photon of higher energy. While this strategy has been recognized in applications ranging from bioimaging to solar energy conversion, its uses in synthetic organic chemistry have not been extensively developed. Here, we present a short tutorial on the theoretical underpinnings and the design principles of TTA-UC systems. Selected applications are then discussed to highlight key features of the TTA mechanism, along with a prospective discussion of the potential of these mechanisms to enable innovation in photocatalysis, methods development, and synthetic organic chemistry.

Crack deflection is studied for the aluminum alloys AA2024-T351 and AA5028-H116 under biaxial fatigue loading. With cruciform specimens that have a testing area of about 420 × 420 mm2 a fatigue crack was subjected to nominal biaxiality ratios between 1.0 and 3.0. Consequently, the crack is subjected to different magnitudes of T-stress. Finite element simulations of the growing crack revealed that the crack path is not significantly influenced by the T-stress but the T-stress predicts whether the crack path remains stable. If at least two crack paths are basically possible the crack will kink for positive T-stresses and remain stable for negative T-stresses. Furthermore, small spikes with strain concentrations along the crack path are identified with digital image correlation which might cause crack deflection in this case.