Erratum to: Electrochemical dissolution of metallic platinum in ionic liquids

The electrochemical dissolution of Pt in several ionic liquids (ILs) was studied. Different ILs were tested assessing their potential to dissolve Pt. Dissolution rate and current efficiency were evaluated. The main focus was on Cl containing ILs: first generation, eutectic-based ILs and second generation ILs with discrete anions. Pt dissolution only occurred in type 1 eutectic-based ILs with a max. dissolution rate of 192.2 g m^?2 h^?1 and a max. current efficiency of 99 % for the ZnCl₂–1-ethyl-3-methylimidazolium chloride IL, and 9.090 g m^?2 h^?1 and 96 % for the 1:1 ZnCl₂–choline chloride IL. The dissolution occurred through the formation of [PtCl_x]^y? complexes. To form these complexes, addition of a metal chloride was necessary. Furthermore, an IL with an electrochemical window of 1.5 V, preferably 2.0 V was required to achieve Pt dissolution. The added metal salt needed to have a higher decomposition potential than 1.5 V or should be a Pt salt.     

Exopolysaccharide Carbohydrate Structure and Biofilm Formation by Rhizobium leguminosarum bv. trifolii Strains Inhabiting Nodules of Trifolium repens Growing on an Old Zn–Pb–Cd-Polluted Waste Heap Area

Heavy metals polluting the 100-year-old waste heap in Bolesław (Poland) are acting as a natural selection factor and may contribute to adaptations of organisms living in this area, including Trifolium repens and its root nodule microsymbionts—rhizobia. Exopolysaccharides (EPS), exuded extracellularly and associated with bacterial cell walls, possess variable structures depending on environmental conditions; they can bind metals and are involved in biofilm formation. In order to examine the effects of long-term exposure to metal pollution on EPS structure and biofilm formation of rhizobia, Rhizobium leguminosarum bv. trifolii strains originating from the waste heap area and a non-polluted reference site were investigated for the characteristics of the sugar fraction of their EPS using gas chromatography mass-spectrometry and also for biofilm formation and structural characteristics using confocal laser scanning microscopy under control conditions as well as when exposed to toxic concentrations of zinc, lead, and cadmium. Significant differences in EPS structure, biofilm thickness, and ratio of living/dead bacteria in the biofilm were found between strains originating from the waste heap and from the reference site, both without exposure to metals and under metal exposure. Received results indicate that studied rhizobia can be assumed as potentially useful in remediation processes.     

Analysis of convective heat and mass transfer coefficients for convective drying of a porous flat plate by conjugate modelling

Convective drying of an unsaturated porous flat plate at low Reynolds numbers (10³) is analysed by means of conjugate modelling of heat and mass transport in the air flow and the porous material. Conjugate modelling does not require knowledge of convective transfer coefficients (CTCs) but allows determining the CTCs a posteriori, hence identifying their spatial and temporal variability, which is the main focus of this study. Comparison is made with porous-material modelling using spatially and/or temporally constant CTCs. Both spatial and temporal variations of the convective boundary conditions are found to have a distinct impact on the drying behaviour: the spatial CTC variation results in two-dimensional drying of the porous material due to leading-edge effects; the temporal CTC variation identifies distinct maxima in the drying rates at the surface right before the surface dries out locally. The CTCs obtained with conjugate modelling remain approximately constant during the constant and decreasing drying rate period (CDRP and DDRP, respectively), but a distinct variation is noticed at the transition of CDRP to DDRP. The heat and mass transfer analogy is found to be valid during the CDRP and to a lesser extent during the DDRP but large discrepancies are found during the transition of CDRP to DDRP. The advantages of conjugate modelling are indicated in this study but the need for detailed modelling of convective boundary conditions is however strongly dependent on the drying behaviour of the porous material and is not always required.     

Modelling Cooling of Packaged Fruit Using 3D Shape Models

This study presents a novel methodology to model the cooling processes of horticultural produce using realistic product shapes rather than commonly used simplified 3D shapes, such as spheres. Variable 3D apple and pear models were created by means of a validated geometric model generator based on X-ray computed tomography images. The fruit were randomly stacked into a geometrical model of a corrugated fibreboard box using the Discrete Element Method. A forced-air cooling process was simulated for three such apple filling patterns using CFD and the results were compared to those obtained with fruit represented by equivalent spheres. No significant difference in average aerodynamic resistance between the real apple shape and its spherical representation was found. The main contributor to the overall pressure drop was the package design rather than product shape. However, large differences in local air velocity and convective heat transfer coefficients were found between the two representations. The degree of cooling uniformity between individual fruit was overestimated when using simplified product shapes: real apple fruit shapes cooled less uniform. This difference between real and simplified product shapes was even larger for a box filled with pear fruit that are more different from a spherical shape. These results demonstrate that improved computer-aided design approaches help in simulating more accurate convective cooling processes. In a next step, such simulations will be used for multi-objective optimization of packaging in terms of cold chain efficiency and cooling uniformity.     

Forgetting and the Ageing of Scientific Publications

In this paper, I will argue that the process of ageing in scientific publications on the one hand, and the process of obsolescence and forgetting to which all kinds of phenomena, people and events are exposed on the other, develop with the same speed. Whereas in the literature on the subject it is stated that the speed of the ageing of scientific literature is exponential, it is shown that the decay from 'age 4' is best described by an inverse function, as was already brought to light in reference to forgetting of people and events as measured by the frequencies of calendar years in large text corpora. The empirical bases are SCI data as presented by Nakamoto and various files of reference data collected by the author. It is shown that the decay curve of the reference frequencies from 'age 4' backwards is independent of time.     

GaAs/AlGaAs nanowire heterostructures studied by scanning tunneling microscopy

We directly image the interior of GaAs/AlGaAs axial and radial nanowire heterostructures with atomic-scale resolution using scanning tunneling microscopy. We show that formation of monolayer sharp and smooth axial interfaces are possible even by vapor-phase epitaxy. However, we also find that instability of the ternary alloys formed in the Au seed fundamentally limits axial heterostructure control, inducing large segment asymmetries. We study radial core-shell nanowires, imaging even ultrathin submonolayer shells. We demonstrate how large twinning-induced morphological defects at the wire surfaces can be removed, ensuring the formation of wires with atomically flat sides.     

CFD analysis of convective heat transfer at the surfaces of a cube immersed in a turbulent boundary layer

Steady Reynolds-Averaged Navier–Stokes (RANS) CFD is used to evaluate the forced convective heat transfer at the surfaces of a cube immersed in a turbulent boundary layer, for applications in atmospheric boundary layer (ABL) wind flow around surface-mounted obstacles such as buildings. Two specific configurations are analysed. First, a cube placed in turbulent channel flow at a Reynolds number of 4.6 × 10³ is considered to validate the numerical predictions by comparison with wind-tunnel measurements. The results obtained with low-Reynolds number modelling (LRNM) show a satisfactory agreement with the experimental data for the windward surface. Secondly, a cube exposed to high-Reynolds number ABL flow is considered. The heat transfer in the boundary layer is analysed in detail. The dimensionless parameter y¹, which takes into account turbulence, is found to be more appropriate for evaluating heat transfer than the commonly used y⁺ value. Standard wall functions, which are frequently used for high-Reynolds number flows, overestimate the convective heat transfer coefficient (CHTC) significantly (±50%) compared to LRNM. The distribution of the CHTC–U₁₀ correlation over the windward surface is reported for Reynolds numbers of 3.5 × 10⁴ to 3.5 × 10⁶ based on the cube height and U₁₀, where U₁₀ is the wind speed in the undisturbed flow at a height of 10 m.     

Modeling the phase equilibria of asymmetric hydrocarbon mixtures using molecular simulation and equations of state

Monte Carlo simulation (MC) is combined with equations of state (EoS) to develop a methodology for the calculation of the vapor–liquid equilibrium (VLE) of multicomponent hydrocarbon mixtures with high asymmetry. MC simulations are used for the calculation of the VLE of binary methane mixtures with long n-alkanes, for a wide range of temperatures and pressures, to obtain sufficient VLE data for the consistent fitting of binary interaction parameters (BIPs) for the EoS. The Soave-Redlich-Kwong (SRK), Peng-Robinson (PR), and Perturbed Chain - Statistical Associating Fluid Theory (PC-SAFT) EoS are considered. The ability of each EoS to correlate the VLE data is assessed and the selected ones are used to predict the VLE of multicomponent gas condensate mixtures. MC simulations proved to be very accurate in predicting the VLE in all conditions and mixtures considered. The BIPs regressed from the simulation dataset lead to equally accurate modeling results for multicomponent mixtures, compared to those regressed from experimental data. © 2018 American Institute of Chemical Engineers AIChE J, 65: 792–803, 2019     

Subfield-specific normalized relative indicators and a new generation of relational charts: Methodological foundations illustrated on the assessment of institutional research performance

A common problem in comparative bibliometric studies at the meso and micro level is the differentiation and specialisation of research profiles of the objects of analysis at lower levels of aggregation. Already the institutional level requires the application of more sophisticated techniques than customary in evaluation of national research performance. In this study institutional profile clusters are used to examine which level of the hierarchical subject-classification should preferably be used to build subject-normalised citation indicators. It is shown that a set of properly normalised indicators can serve as a basis of comparative assessment within and even among different clusters, provided that their profiles still overlap and such comparison is thus meaningful. On the basis of 24 selected European universities, a new version of relational charts is presented for the comparative assessment of citation impact.     

Pharao: pharmacophore alignment and optimization

Within the context of early drug discovery, a new pharmacophore-based tool to score and align small molecules (Pharao) is described. The tool is built on the idea to model pharmacophoric features by Gaussian 3D volumes instead of the more common point or sphere representations. The smooth nature of these continuous functions has a beneficent effect on the optimization problem introduced during alignment. The usefulness of Pharao is illustrated by means of three examples: a virtual screening of trypsin-binding ligands, a virtual screening of phosphodiesterase 5-binding ligands, and an investigation of the biological relevance of an unsupervised clustering of small ligands based on Pharao.