Preparation of nano and Angstrom sized cobalt ensembles and their performance in the Fischer-Tropsch synthesis

Includes bibliographical references.In Fischer-Tropsch synthesis carbon monoxide and hydrogen are converted in a surface polymerisation reaction over a heterogeneous catalyst to mainly long chain hydrocarbons and water. Although all group VIII metals are reported to show activity in this process, only iron and cobalt are used on an industrial scale due to availability and costs. In order to minimise the costs of these catalysts it is generally important to increase the mass specific active surface area by dispersing the active material on an inert carrier. Recent studies on nano sized iron, cobalt, ruthenium and rhodium crystallites indicate that below a certain crystallite size they display a decrease in surface specific activity. This work aims to study the crystallite size effect of cobalt, supported on an industrially relevant carrier material, on activity and selectivity in the Fischer-Tropsch synthesis

Four-quark states with charm quarks in a two-body Bethe-Salpeter approach

We study the internal structure of a range of four-quark states with charm quark contributions using a two-body Bethe-Salpeter equation. Thereby, we examine charmonium-like states with hidden charm and quark content $c\bar{c}q\bar{q}$, open-charm states with quark content $cc\bar{q}\bar{q}$ and all-charm states with $cc\bar{c}\bar{c}$. In particular we study the internal competition between meson-meson components and diquark-antidiquark components in the wave functions of these states. Our results indicate that the $\chi_{c1}(3872)$ and the $Z_c(3900)$ are predominantly $D\bar D^*$ states and that the recently discovered open-charm state $T_{cc}^+$ is dominated by an internal $DD^*$ component. In both cases the diquark components are negligible. For the all-charm state $X(6900)$ with as yet unknown quantum numbers we identify candidates in the excitation spectra of $0^+$ and $1^+$ states. Furthermore, our framework serves to provide predictions for further, yet undiscovered open and hidden charm four-quark states.Comment: 9 pages, 4 figures; v2: minor changes, version accepted for EPJ

Datafication of Knowledge Work: A Framework and Research Agenda

Datafication is moving into the center of value creation in the knowledge intensive organization. Datafication describes the transformation of qualitative behavior and tacit knowledge into quantified actions and codified data. While traditional assumptions on knowledge work highlights individual autonomy in shaping job tasks and fitting abilities for productive work, the consequences of datafication for knowledge work are not yet well understood. We build on the contingency theory of performance as theoretical lens to derive a framework that addresses relevant future research questions in the evolving field of datafication in knowledge work. The proposed multi-level framework considers assumptions and elements from traditional productive knowledge work in combination with determinants of digital workplaces and organizational factors along the lines of data-based value creation and (semi-)automated decision making. For the future, we suggest viewing datafied knowledge work as a socio-technical phenomenon, thereby constituted of human-dominated knowledge work in convergence with technological-dominated algorithmic thinking

Lyndon Words Accelerate Suffix Sorting

Suffix sorting is arguably the most fundamental building block in string algorithmics, like regular sorting in the broader field of algorithms. It is thus not surprising that the literature is full of algorithms for suffix sorting, in particular focusing on their practicality. However, the advances on practical suffix sorting stalled with the emergence of the DivSufSort algorithm more than 10 years ago, which, up to date, has remained the fastest suffix sorter. This article shows how properties of Lyndon words can be exploited algorithmically to accelerate suffix sorting again. Our new algorithm is 6-19% faster than DivSufSort on real-world texts, and up to three times as fast on artificial repetitive texts. It can also be parallelized, where similar speedups can be observed. Thus, we make the first advances in practical suffix sorting after more than a decade of standstill

Artificial Intelligence and Digital Work: The Sociotechnical Reversal

A well-designed information system (IS) in the classical view comprises two interrelated yet different subsystems; one that represents the technological dimension of work; and one that represents the social dimension. When these subsystems are heralded as equally important, they constitute a sociotechnical whole, producing economic outcomes such as profit and efficiency, plus humanistic outcomes, such as engagement and well-being. We see, increasingly, this classical view becoming obliviated. In this conceptual paper, we reflect upon the role of humans and technology in these changing work environments. While technical aspects from Artificial Intelligence and digital technologies are dominating the social side of work, we suggest a sociotechnical reversal to happen. Whereas this technosocial reality might be well motivated by advances in efficiency and productivity, the effects on well-being and engagement are less well understood. Consequently, we provide a set of theoretically derived principles to guide these changes in the digital workplace

Highlights from Faraday Discussion: Designing New Heterogeneous Catalysts, London, UK, April 2016

The Faraday Discussion on the design of new heterogeneous catalysts took place from 4–6 April 2016 in London, United Kingdom.</p

Austrian Outbound Foreign Direct Investment in Europe: A spatial econometric study

This paper focuses on Austrian outbound foreign direct investment (FDI, measured by sales of Austrian affiliates abroad) in Europe over the period 2009-2013, using a spatial Durbin panel data model specification with fixed effects, and a spatial weight matrix based on the first-order contiguity relationship of the countries and normalised by its largest eigenvalue. Third-country effects essentially enter the empirical analysis in two major ways: first, by the endogenous spatial lag on FDI (measured by FDI into markets nearby the host country), and, second, by including an exogenous market potential variable that measures the size of markets nearby the FDI host country in terms of gross domestic product. The question whether the empirical result is compatible with horizontal, vertical, export-platform or complex vertical FDI then depends on the sign and significance levels of both the coefficient of the spatial lag on FDI and the direct impact estimate of the market potential variable. The paper yields robust results that provide significant empirical evidence for horizontal FDI as the main driver of Austrian outbound FDI in Europe. This result is strengthened by the indirect impact estimate of the market potential variable indicating that spatial spillovers do not matter.Series: Working Papers in Regional Scienc

The role of symmetry in driven propulsion at low Reynolds number

We theoretically and experimentally investigate low-Reynolds-number propulsion of geometrically achiral planar objects that possess a dipole moment and that are driven by a rotating magnetic field. Symmetry considerations (involving parity, $\widehat{P}$, and charge conjugation, $\widehat{C}$) establish correspondence between propulsive states depending on orientation of the dipolar moment. Although basic symmetry arguments do not forbid individual symmetric objects to efficiently propel due to spontaneous symmetry breaking, they suggest that the average ensemble velocity vanishes. Some additional arguments show, however, that highly symmetrical ($\widehat{P}$-even) objects exhibit no net propulsion while individual less symmetrical ($\widehat{C}\widehat{P}$-even) propellers do propel. Particular magnetization orientation, rendering the shape $\widehat{C}\widehat{P}$-odd, yields unidirectional motion typically associated with chiral structures, such as helices. If instead of a structure with a permanent dipole we consider a polarizable object, some of the arguments have to be modified. For instance, we demonstrate a truly achiral ($\widehat{P}$- and $\widehat{C}\widehat{P}$-even) planar shape with an induced electric dipole that can propel by electro-rotation. We thereby show that chirality is not essential for propulsion due to rotation-translation coupling at low Reynolds number.Comment: 5 pages, 5 figure