Aging dynamics of ferromagnetic and reentrant spin glass phases in stage-2 Cu0.80_{0.80}C0.20_{0.20}Cl2_{2} graphite intercalation compound

Aging dynamics of a reentrant ferromagnet stage-2 Cu$_{0.8}$Co$_{0.2}$Cl$_{2}$ graphite intercalation compound has been studied using DC magnetic susceptibility. This compound undergoes successive transitions at the transition temperatures $T_{c}$ ($\approx 8.7$ K) and $T_{RSG}$ ($\approx 3.3$ K). The relaxation rate $S_{ZFC}(t)$ exhibits a characteristic peak at $t_{cr}$ below $T_{c}$. The peak time $t_{cr}$ as a function of temperature $T$ shows a local maximum around 5.5 K, reflecting a frustrated nature of the ferromagnetic phase. It drastically increases with decreasing temperature below $T_{RSG}$. The spin configuration imprinted at the stop and wait process at a stop temperature $T_{s}$ ($<T_{c}$) during the field-cooled aging protocol, becomes frozen on further cooling. On reheating, the memory of the aging at $T_{s}$ is retrieved as an anomaly of the thermoremnant magnetization at $T_{s}$. These results indicate the occurrence of the aging phenomena in the ferromagnetic phase ($T_{RSG}<T<T_{c}$) as well as in the reentrant spin glass phase ($T<T_{RSG}$).Comment: 9 pages, 9 figures; submitted to Physical Review

Toward an Integrated Competence-based System Supporting Lifelong Learning and Employability: Concepts, Model, and Challenges

Miao, Y., Van der Klink, M., Boon, J., Sloep, P. B., & Koper, R. (2009). Toward an Integrated Competence-based System Supporting Lifelong Learning and Employability: Concepts, Model, and Challenges. In M. Spaniol, Q. Li, R. Klamma & R. W. H. Lau (Eds.), Proceedings of the 8th International Conference Advances in Web Based Learning - ICWL 2009 (pp. 265-276). August, 19-21, 2009, Aachen, Germany. Lecture Notes in Computer Science 5686; Berlin, Heidelberg: Springer-Verlag.Efficient and effective lifelong learning requires that people can make informed decisions about their continuous personal development in the different stages of their lives. In this paper we state that lifelong learners need to be characterized as decision-makers. In order to improve the quality of their decisions we propose the development of an integrated lifelong learning and employment support system, which traces learners’ competence development and provides a decision support environment. An abstract conceptual model has been developed and the main design ideas have been documented using Z notation. Moreover, we analyzed the main technical challenges for the realization of the target system: competence information fusion, decision analysis models, spatial indexing structures and browsing structures and visualization of competence related information objects.The work on this publication has been sponsored by the TENCompetence Integrated Project that is funded by the European Commission's 6th Framework Programme, priority IST/Technology Enhanced Learning. Contract 027087 [http://www.tencompetence.org

Determination of the basic timescale in kinetic Monte Carlo simulations by comparison with cyclic-voltammetry experiments

While kinetic Monte Carlo simulations can provide long-time simulations of the dynamics of physical and chemical systems, it is not yet possible in general to identify the inverse Monte Carlo attempt frequency with a physical timescale. Here we demonstrate such an identification by comparing simulations with experimental data. Using a dynamic lattice-gas model for the electrosorption of Br on Ag(100), we measure the scan-rate dependence of the separation between positive-and negative-going peaks in cyclic-voltammetry (CV) and compare simulated and experimental peak separations. By adjusting the Monte Carlo attempt frequency, good agreement between simulated and experimental peak separations is achieved. It is also found that the uniqueness of such a determination is dependent on the relative values of the adsorption/desorption and diffusion free-energy barriers.Comment: Accepted for publication in Surface Science Letters,8 pages, 4 figure

Landing and catalytic characterization of individual nanoparticles on electrode surfaces

We demonstrate a novel and versatile pipet-based approach to study the landing of individual nanoparticles (NPs) on various electrode materials without any need for encapsulation or fabrication of complex substrate electrode structures, providing great flexibility with respect to electrode materials. Because of the small electrode area defined by the pipet dimensions, the background current is low, allowing for the detection of minute current signals with good time resolution. This approach was used to characterize the potential-dependent activity of Au NPs and to measure the catalytic activity of a single NP on a TEM grid, combining electrochemical and physical characterization at the single NP level for the first time. Such measurements open up the possibility of studying the relation between the size, structure and activity of catalyst particles unambiguously

Aryl hydrocarbon receptor activation during in vitro and in vivo digestion of raw and cooked broccoli (brassica oleracea var. Italica)

Broccoli is rich in glucosinolates, which can be converted upon chewing and processing into Aryl hydrocarbon Receptor (AhR) ligands. Activation of AhR plays an important role in overall gut homeostasis but the role of broccoli processing on the generation of AhR ligands is still largely unknown. In this study, the effects of temperature, cooking method (steaming versus boiling), gastric pH and further digestion of broccoli on AhR activation were investigated in vitro and in ileostomy subjects. For the in vitro study, raw, steamed (t = 3 min and t = 6 min) and boiled (t = 3 min and t = 6 min) broccoli were digested in vitro with different gastric pH. In the in vivo ileostomy study, 8 subjects received a broccoli soup or a broccoli soup plus an exogenous myrosinase source. AhR activation was measured in both in vitro and in vivo samples by using HepG2-Lucia™ AhR reporter cells. Cooking broccoli reduced the AhR activation measured after gastric digestion in vitro, but no effect of gastric pH was found. Indole AhR ligands were not detected or detected at very low levels both after intestinal in vitro digestion and in the ileostomy patient samples, which resulted in no AhR activation. This suggests that the evaluation of the relevance of glucosinolates for AhR modulation in the gut cannot prescind from the way broccoli is processed, and that broccoli consumption does not necessarily produce substantial amounts of AhR ligands in the large intestine

Electrocatalytic reduction of Nitrate on Copper single crystals in acidic and alkaline solutions

Catalysis and Surface Chemistr

Interconversions of nitrogen-containing species on Pt(100) and Pt(111) electrodes in acidic solutions containing nitrate

This work deals with the interconversions of various nitrogen-containing compounds on Pt(111) and Pt(100) electrodes in contact with acidic solutions of nitrate. Via its reduction, nitrate acts merely as the source of adsorbed nitrogen-containing intermediates, which then undergo complex oxidative or reductive transformations depending on the electrode potential. Nitrate reduction to ammonium is structure sensitive on Pt(111) and Pt(100) because it is mediated by *NO, the adsorption and reactivity of which is also structure sensitive. Accordingly, previous knowledge from *NO electrochemistry is useful to streamline nitrate reduction and elaborate a comprehensive picture of nitrogen-cycle electrocatalysis. Our overall conclusion for nitrate reduction is that the complete conversion to ammonium under prolonged electrolysis is possible only if the reduction of nitrate to nitric oxide, and the reduction of nitric oxide to ammonium are feasible at the applied potential. Among the two surfaces studied here, this condition is fulfilled by Pt(111) in a narrow potential region. (C) 2018 Elsevier Ltd. All rights reserved.Catalysis and Surface Chemistr

Ab initio calculations for bromine adlayers on the Ag(100) and Au(100) surfaces: the c(2x2) structure

Ab initio total-energy density-functional methods with supercell models have been employed to calculate the c(2x2) structure of the Br-adsorbed Ag(100) and Au(100) surfaces. The atomic geometries of the surfaces and the preferred bonding sites of the bromine have been determined. The bonding character of bromine with the substrates has also been studied by analyzing the electronic density of states and the charge transfer. The calculations show that while the four-fold hollow-site configuration is more stable than the two-fold bridge-site topology on the Ag(100) surface, bromine prefers the bridge site on the Au(100) surface. The one-fold on-top configuration is the least stable configuration on both surfaces. It is also observed that the second layer of the Ag substrate undergoes a small buckling as a consequence of the adsorption of Br. Our results provide a theoretical explanation for the experimental observations that the adsorption of bromine on the Ag(100) and Au(100) surfaces results in different bonding configurations.Comment: 10 pages, 4 figure, 5 tables, Phys. Rev. B, in pres