Boosting hot electron flux and catalytic activity at metal-oxide interfaces of PtCo bimetallic nanoparticles

Despite numerous studies, the origin of the enhanced catalytic performance of bimetallic nanoparticles (NPs) remains elusive because of the ever-changing surface structures, compositions, and oxidation states of NPs under reaction conditions. An effective strategy for obtaining critical clues for the phenomenon is real-time quantitative detection of hot electrons induced by a chemical reaction on the catalysts. Here, we investigate hot electrons excited on PtCo bimetallic NPs during H-2 oxidation by measuring the chemicurrent on a catalytic nanodiode while changing the Pt composition of the NPs. We reveal that the presence of a CoO/Pt interface enables efficient transport of electrons and higher catalytic activity for PtCo NPs. These results are consistent with theoretical calculations suggesting that lower activation energy and higher exothermicity are required for the reaction at the CoO/Pt interface

Comparing Petri Net and Activity Diagram Variants for Workflow Modelling:A Quest for Reactive Petri Nets

Petri net variants are widely used as a workflow modelling technique. Recently, UMLa ctivity diagrams have been used for the same purpose, even though the syntax and semantics of activity diagrams has not been yet fully worked out. Nevertheless, activity diagrams seem very similar to Petri nets and on the surface, one may think that they are variants of each other. To substantiate or deny this claim, we need to formalise the intended semantics of activity diagrams and then compare this with various Petri net semantics. In previous papers we have defined two formal semantics for UMLact ivity diagrams that are intended for workflow modelling. In this paper, we discuss the design choices that underlie these two semantics and investigate whether these design choices can be met in low-level and high-level Petri net semantics. We argue that the main difference between the Petri net semantics and our semantics of UML act ivity diagrams is that the Petri net semantics models resource usage of closed, active systems that are non-reactive, whereas our semantics of UMLact ivity diagrams models open, reactive systems. Since workflow systems are open, reactive systems, we conclude that Petri nets cannot model workflows accurately, unless they are extended with a syntax and semantics for reactivity

Learners in a Changing Learning Landscape: Reflections from an Instructional Design Perspective

Van Merriënboer, J. J. G., & Stoyanov, S. (2008). Learners in a changing learning landscape: Reflections from an instructional design perspective. In J. Visser & M. Visser-Valfrey (Eds.), Learners in a changing learning landscape: Reflections from a dialogue on new roles and expectations (pp. 69-90). Dordrecht, The Netherlands: Springer.Both learners and teachers find themselves in a learning landscape that is rapidly changing, along with fast societal and technological developments. This paper discusses the new learning landscape from an instructional design perspective. First, with regard to what is learned, people more than ever need flexible problem-solving and reasoning skills allowing them to deal with new, unfamiliar problem situations in their professional and everyday life. Second, with regard to the context in which learning takes place, learning in technology-rich, informal and professional 24/7 settings is becoming general practice. And third, with regard to the learners themselves, they can more often be characterized as lifelong learners who are mature, bring relevant prior knowledge, and have very heterogeneous expectations and perceptions of learning. High-quality instructional design research should focus on the question which instructional methods and media-method combinations are effective, efficient and appealing in this new learning landscape. Some innovative instructional methods that meet this requirement are discussed

Lipid remodelling in the reef-building honeycomb worm, Sabellaria alveolata, reflects acclimation and local adaptation to temperature

Acclimation and adaptation, which are key to species survival in a changing climate, can be observed in terms of membrane lipid composition. Remodelling membrane lipids, via homeoviscous adaptation (HVA), counteracts membrane dysfunction due to temperature in poikilotherms. In order to assess the potential for acclimation and adaptation in the honeycomb worm, Sabellaria alveolata, a reefbuilding polychaete that supports high biodiversity, we carried out common-garden experiments using individuals from along its latitudinal range. Individuals were exposed to a stepwise temperature increase from 15 °C to 25 °C and membrane lipid composition assessed. Our results suggest that S. alveolata was able to acclimate to higher temperatures, as observed by a decrease in unsaturation index and 20:5n-3. However, over the long-term at 25 °C, lipid composition patterns are not consistent with HVA expectations and suggest a stress response. Furthermore, unsaturation index of individuals from the two coldest sites were higher than those from the two warmest sites, with individuals from the thermally intermediate site being in-between, likely reflecting local adaptation to temperature. Therefore, lipid remodelling appears limited at the highest temperatures in S. alveolata, suggesting that individuals inhabiting warm environments may be close to their upper thermal tolerance limits and at risk in a changing climate

Die Politische Ökonomie Beruflicher Weiterbildung: Der Einfluss von Tarifverträgen auf Arbeitgeberinvestitionen und Teilnahmequoten

Warum sind aber Arbeitgeber in einigen Ländern bereit, sich an Weiterbildungsmaßnahmen ihrer Mitarbeiter zu beteiligen, während dies in anderen Ländern nicht der Fall ist? In diesem Artikel wird die tarifvertragliche Abdeckung als zentraler Mechanismus hierfür herausgearbeitet: Einerseits intendiert, durch vertraglich geregelte Weiterbildungsmaßnahmen, und anderseits unintendiert, durch die Angleichung von Löhnen zwischen Firmen. Mithilfe von Mehrebenenregressionsanalysen auf Basis von Daten des European Social Survey kann gezeigt werden, dass Tarifverträge einen postiven Effekt auf die Finanzierungsbeteiligung von Arbeitgebern haben, sowie auf individuelle Teilnahmen. Diese Ergebnisse legen nahe, dass institutionelle Faktoren gewichtige Einflussgrößen in Erklärungen von Firmeninvestitionen und Weiterbildungsbeteiligung sind. In einer abschließenden Diskussion werden diese Funde im Kontext der internationalen Debatte um die Dezentralisierung korporatistischer Arrangements besprochen.Why are employers in some countries willing to pay for further training of their employees, but not in other countries. In this article, it is argued that the central mechanism for this is collective bargaining coverage. On the one hand, intentionally through contractual regulations regarding further training. On the other hand, unintentionally through equalization of wages between companies. Using multilevel-regression based on data from the European Social Survey, results indicate a positive effect of collective bargaining coverage on employer’s willingness to pay for further training, as well as on participation in further training. These results suggest institutions are significant factors in explanations of firm investments into skills and further training. In a concluding discussion, findings are reviewed in the context of the international debate about decentralization of corporatist arrangements

Rotational analysis of the origin and the inversion bands in the S1 (A2) ¬ S 0 (A1) electronic spectrum of acetaldehyde

Fully rotationally resolved spectra of the two lowest-frequency bands ~the origin (00 0 ) and the inversion (140 1) band! of the S1(n p*)ÃS0 transition of jet-cooled (Trot'6 K) acetaldehyde, CH3CHO, have been recorded with a resolution of '0.01 cm21 using a pulsed dye amplified continuous wave ~cw! laser. In modeling the spectra a nonperturbative solution of the rotational– torsional coupling problem was used, but the torsion–inversion and the rotation–inversion couplings were neglected. All the lines of the origin band were reproduced with a model using the same rotational–torsional Hamiltonian for the ground- and excited electronic state. The inversion band could not be described with this model, since the ordering of the torsional levels in the excited state is reversed. The measured spectrum was reproduced by using a rigid asymmetric rotor Hamiltonian for the two torsional levels in the excited state. Some rotational levels of 00 and 141 states were found to be shifted from their predicted energy values. These shifts were explained by an accidental resonance between the excited singlet level and some higher rovibronic triplet level. The relative intensities of the ab-type and c-type torsional subbands and the Herzberg–Teller– induced transition dipole moment direction, characterizing the ab-type subband, were determined by an intensity fit

Closing the gap between experiment and theory: Reactive scattering of HCl from Au(111)

Accurate simulation of molecules reacting on metal surfaces, which can help in improving heterogeneous catalysts, remains out of reach for several reactions. For example, a large disagreement between theory and experiment for HCl reacting on Au(111) still remains, despite many efforts. In this work, the dissociative chemisorption of HCl on Au(111) is investigated with a recently developed MGGA density functional (MS-RPBEl) and a high-dimensional neural network potential. Additionally, previous experimental sticking probabilities are re-examined. A considerably improved agreement between experiment and theory is obtained, although theory still overestimates experimental sticking probabilities by a factor of 2–7 at the highest incidence energy. Computed and measured vibrational transition probabilities are also in improved agreement. Several dynamical effects such as angular steering and energy transfer from the molecule to the surface are found to play an important role