Comparing open-source DEM frameworks for simulations of common bulk processes

Multiple software frameworks based on the Discrete Element Method (DEM) are available for simulating granular materials. All of them employ the same principles of explicit time integration, with each time step consisting of three main steps: contact detection, calculation of interactions, and integration of the equations of motion. However, there exist significant algorithmic differences, such as the choice of contact models, particle and wall shapes, and data analysis methods. Further differences can be observed in the practical implementation, including data structures, architecture, parallelization and domain decomposition techniques, user interaction, and the documentation of resources.This study compares, verifies, and benchmarks nine widely-used software frameworks. Only open-source packages were considered, as these are freely available and their underlying algorithms can be reviewed, edited, and tested. The benchmark consists of three common bulk processes: silo emptying, drum mixing, and particle impact. To keep it simple and comparable, only standard features were used, such as spherical particles and the Hertz-Mindlin model for dry contacts. Scripts for running the benchmarks in each software are provided as a dataset

Visualization of characteristics of the contact network between spheres in 3D assembly

Analysis of geometrical features of 3D granular assemblies poses difficulties in visualization of the effects taking place within the volume of the sample. This work presents the method for visualization of spatial distribution of the contact points in a monodisperse; frictional assembly composed of spheres and generated using three filling methods for a cuboidal or cylindrical container. The visualization is based on the projection of the contact points between particles on a hypothetical sphere followed by their representation on the plane. The proposed method was found to adequately visualize differences in the spatial structure of assemblies generated using various filling methods

Visualization of characteristics of the contact network between spheres in 3D assembly

Analysis of geometrical features of 3D granular assemblies poses difficulties in visualization of the effects taking place within the volume of the sample. This work presents the method for visualization of spatial distribution of the contact points in a monodisperse; frictional assembly composed of spheres and generated using three filling methods for a cuboidal or cylindrical container. The visualization is based on the projection of the contact points between particles on a hypothetical sphere followed by their representation on the plane. The proposed method was found to adequately visualize differences in the spatial structure of assemblies generated using various filling methods

AcrB: a mean, keen, drug efflux machine

Gram‐negative bacteria are intrinsically resistant against cytotoxic substances by means of their outer membrane and a network of multidrug efflux systems, acting in synergy. Efflux pumps from various superfamilies with broad substrate preferences sequester and pump drugs across the inner membrane to supply the highly polyspecific and powerful tripartite resistance–nodulation–cell division (RND) efflux pumps with compounds to be extruded across the outer membrane barrier. In Escherichia coli, the tripartite efflux system AcrAB–TolC is the archetype RND multiple drug efflux pump complex. The homotrimeric inner membrane component acriflavine resistance B (AcrB) is the drug specificity and energy transduction center for the drug/proton antiport process. Drugs are bound and expelled via a cycle of mainly three consecutive states in every protomer, constituting a flexible alternating access channel system. This review recapitulates the molecular basis of drug and inhibitor binding, including mechanistic insights into drug efflux by AcrB. It also summarizes 17 years of mutational analysis of the gene acrB, reporting the effect of every substitution on the ability of E. coli to confer resistance toward antibiotics (http://goethe.link/AcrBsubstitutions). We emphasize the functional robustness of AcrB toward single‐site substitutions and highlight regions that are more sensitive to perturbation

DATA CENTERS IN THE SCIENTIFIC INFORMATION INFRASTRUCTURE

There is a multiple increase of the volume of scientific data obtained in the course of research each year. Due to this there is a need for continuous improvement, such as data transmission channels and systems for handling and storage of scientific data. For example, data centers show current centers and storage of scientific data and advanced technology in this area, in particular the "cloud" technology. Particular attention is paid to the information infrastructure for data centers storing scientific information

Temperature Dependence of CsI:Tl Scintillation Pulse Shapes from -183°C to +90°C Measured with a SiPM Readout

A custom designed cryostat was constructed to measure the response of a CsI:Tl scintillator in temperature range from -183°C up to +90°C. The light readout was realized using a SiPM developed by FBK in near ultraviolet high density (NUV-HD) technology. The crystal and the SiPM were installed on separated copper frames. The crystal was cooled down by liquid nitrogen, while the SiPM was kept at temperature close to room temperature. A separation of 1 mm was kept between the crystal and the photodetector to ensure thermal isolation. The temperature of the crystal could be varied by heaters on the scintillator frame and was continuously monitored using a coil shaped resistance thermometer. The CsI:Tl scintillation decay profiles were recorded in the entire temperature range provided by the cryostat

Scintillation response to gamma-rays measured at wide temperature range for Tl doped CsI with SiPM readout

A custom design cryostat was constructed to study the temperature dependence of relative light yield and non-proportionality trends of scintillators between −182 °C and ＋152 °C. CsI:Tl crystal response to γ-rays and X-rays was investigated between 14 keV and 662 keV. Scintillation light was detected by a SiPM device, which was installed on a copper frame separated from the crystal and the cooling rod to enable operating the device at room temperature. The scintillation efficiency of CsI:Tl is peaked at about room temperature. The light yield of CsI:Tl at temperature close to liquid nitrogen boiling point is reduced by a factor of 15 in comparison to room temperature conditions. The non-proportionality of CsI:Tl scintillation response is high at low temperatures and is getting more proportional with increasing temperature