Aggregation and clogging phenomena of rigid microparticles in microfluidics

We developed a numerical tool to investigate the phenomena of aggregation and clogging of rigid microparticles suspended in a Newtonian fluid transported through a straight microchannel. In a first step, we implement a time-dependent one-way coupling Discrete Element Method (DEM) technique to simulate the movement and effect of adhesion on rigid microparticles in two- and three-dimensional computational domains. The Johnson–Kendall–Roberts (JKR) theory of adhesion is applied to investigate the contact mechanics of particle–particle and particle–wall interactions. Using the one-way coupled solver, the agglomeration, aggregation and deposition behavior of the microparticles is studied by varying the Reynolds number and the particle adhesion. In a second step, we apply a two-way coupling CFD–DEM approach, which solves the equation of motion for each particle, and transfers the force field corresponding to particle–fluid interactions to the CFD toolbox OpenFOAM. Results for the one-way (DEM) and two-way (CFD–DEM) coupling techniques are compared in terms of aggregate size, aggregate percentages, spatial and temporal evaluation of aggregates in 2D and 3D. We conclude that two-way coupling is the more realistic approach, which can accurately capture the particle–fluid dynamics in microfluidic applications.     

Engineering the Interlayer Spacing by Pre-Intercalation for High Performance Supercapacitor MXene Electrodes in Room Temperature Ionic Liquid

MXenes exhibit excellent capacitance at high scan rates in sulfuric acid aqueous electrolytes, but the narrow potential window of aqueous electrolytes limits the energy density. Organic electrolytes and room-temperature ionic liquids (RTILs) can provide higher potential windows, leading to higher energy density. The large cation size of RTIL hinders its intercalation in-between the layers of MXene limiting the specific capacitance in comparison to aqueous electrolytes. In this work, different chain lengths alkylammonium (AA) cations are intercalated into Ti₃C₂T_x, producing variation of MXene interlayer spacings (d-spacing). AA-cation-intercalated Ti₃C₂T_x (AA-Ti₃C₂), exhibits higher specific capacitances, and cycling stabilities than pristine Ti₃C₂T_x in 1 m 1-ethly-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMIMTFSI) in acetonitrile and neat EMIMTFSI RTIL electrolytes. Pre-intercalated MXene with an interlayer spacing of ≈2.2 nm, can deliver a large specific capacitance of 257 F g⁻¹ (1428 mF cm⁻² and 492 F cm⁻³) in neat EMIMTFSI electrolyte leading to high energy density. Quasi elastic neutron scattering and electrochemical impedance spectroscopy are used to study the dynamics of confined RTIL in pre-intercalated MXene. Molecular dynamics simulations suggest significant differences in the structures of RTIL ions and AA cations inside the Ti₃C₂T_x interlayer, providing insights into the differences in the observed electrochemical behavior.     

The Advantage of Nanowire Configuration in Band Structure Determination

Earth-abundant and environmentally friendly semiconductors offer a promising path toward low-cost mass production of solar cells. A critical aspect in exploring new semiconducting materials and demonstrating their enhanced functionality consists in disentangling them from the artifacts of defects. Nanowires are diameter-tailored filamentary structures that tend to be defect-free and thus ideal model systems for a given material. Here, an additional advantage is demostrated, which is the determination of the band structure, by performing high energy and spatial resolution electron energy-loss spectroscopy in aloof and inner beam geometry in a scanning transmission electron microscope. The experimental results are complemented by spectroscopic ellipsometry and are excellently correlated with first principles calculations. This study opens the path for characterizing the band structure of new compounds in a non-destructive and prompt manner, strengthening the route of new materials discovery.     

The Fractional CIO in SMEs: conceptualization and research agenda

We conceptualize the new phenomenon of the Fractional Chief Information Officer (CIO) as a part-time executive who usually works for more than one primarily small- to medium-sized enterprise (SME) and develop promising avenues for future research on Fractional CIOs. We conduct an empirical study by drawing on semi-structured interviews with 40 individuals from 10 different countries who occupy a Fractional CIO role. We derive a definition for the Fractional CIO, distinguish it from other forms of employment, and compare it with existing research on CIO roles. Further, we find four salient engagement types of Fractional CIOs offering value for SMEs in various situations: Strategic IT management, Restructuring, Rapid scaling, and Hands-on support. The results reveal similarities with existing CIO roles as well as novel insights concerning the different engagement types. Lastly, we propose a research agenda for the Fractional CIO field, based on four research themes derived from existing CIO research and insights from the interviews.

     

High-probability minimax probability machines

In this paper we focus on constructing binary classifiers that are built on the premise of minimising an upper bound on their future misclassification rate. We pay particular attention to the approach taken by the minimax probability machine (Lanckriet et al. in J Mach Learn Res 3:555–582, 2003), which directly minimises an upper bound on the future misclassification rate in a worst-case setting: that is, under all possible choices of class-conditional distributions with a given mean and covariance matrix. The validity of these bounds rests on the assumption that the means and covariance matrices are known in advance, however this is not always the case in practice and their empirical counterparts have to be used instead. This can result in erroneous upper bounds on the future misclassification rate and lead to the formulation of sub-optimal predictors. In this paper we address this oversight and study the influence that uncertainty in the moments, the mean and covariance matrix, has on the construction of predictors under the minimax principle. By using high-probability upper bounds on the deviation between true moments and their empirical counterparts, we can re-formulate the minimax optimisation to incorporate this uncertainty and find the predictor that minimises the high-probability, worst-case misclassification rate. The moment uncertainty introduces a natural regularisation component into the optimisation, where each class is regularised in proportion to the degree of moment uncertainty. Experimental results would support the view that in the case of with limited data availability, the incorporation of moment uncertainty can lead to the formation of better predictors.     

Mass Spectrometric Analysis of Cerebrospinal Fluid Ubiquitin in Alzheimer's Disease and Parkinsonian Disorders

1 Purpose

Dysfunctional proteostasis, with decreased protein degradation and an accumulation of ubiquitin into aggregated protein inclusions, is a feature of neurodegenerative diseases. Identifying new potential biomarkers in cerebrospinal fluid (CSF) reflecting this process could contribute important information on pathophysiology.

2 Experimental design

A developed method combining SPE and PRM‐MS is employed to monitor the concentration of ubiquitin in CSF from subjects with Alzheimer's disease (AD), Parkinson's disease (PD), and progressive supranuclear palsy (PSP). Four independent cross‐sectional studies are conducted, studies 1–4, including controls (n = 86) and participants with AD (n = 60), PD (n = 15), and PSP (n = 11).

3 Results

The method shows a repeatability and intermediate precision not exceeding 6.1 and 7.9%, respectively. The determined LOD is 0.1 nm and the LOQ range between 0.625 and 80 nm . The CSF ubiquitin concentration is 1.2–1.5‐fold higher in AD patients compared with controls in the three independent AD‐control studies (Study 1, p < 0.001; Study 2, p < 0.001; and Study 3, p = 0.003). In the fourth study, there is no difference in PD or PSP, compared to controls.

4 Conclusion and clinical relevance

CSF ubiquitin may reflect dysfunctional proteostasis in AD. The described method can be used for further exploration of ubiquitin as a potential biomarker in neurodegenerative diseases.     

Evidence for the mitochondrial biosynthesis of 3R-hydroxy-5Z,8Z,11Z,14Z-eicosatetraenoic acid in the yeast Dipodascopsis uninucleata

The biosynthesis of 3R-hydroxy-5Z,8Z,11Z,14Z-eicosatetraenoic acid (3R-HETE) from arachidonic acid (20∶4n−6) by the hyphal-forming yeast, Dipodascopsis uninucleata, in cell-free enzyme extracts required CoASH, ATP, NAD⁺ and Mg²⁺; 3R-HETE was present as the CoA derivative in enzyme extracts and its biosynthesis was associated with mitochondria. Its synthesis was high from arachidonoyl-CoA (15% conversion of the substrate; 22 nmol mg protein⁻¹·h), but significantly higher from trans-2-arachidonoyl-CoA (53 nmol mg protein⁻¹·min). Aspirin, an inhibitor of prostaglandin endoperoxide synthase synthase (cyclooxygenase), did not significantly inhibit 3R-HETE biosynthesis in enzyme extracts, as opposed to antimycin A (46% inhibition). The chirality of 3-HETE was 95% R and 5% S. 3R-HETE has the same chirality as the products of peroxisomal enoyl-CoA hydratases of Neurospora crassa and Saccharomyces cerevisiae; the difference appears to be that in D. uninucleata the R-enantiomers are synthesized in mitochondria. Exogenously supplied eicosapentaenoic acid was converted to 3-hydroxy 5Z,11Z,14Z,17Z-eicosapentaenoic acid by cell-free enzyme extracts though there was no requirement for a 5Z,8Z-diene structure for the biosynthesis of 3-hydroxylated fatty acids as 3-hydroxy-8Z,11Z,14Z, and 3-hydroxy-11Z,14Z,17Z-eicosatrienoic acids were synthesized from the corresponding fatty acids. We found no evidence for the synthesis of the prostaglandins F_2α and F₂.     

Die diskontinuierliche Zentrifuge als Betriebssystem in der Chemischen Industrie

Discontinuous centrifuges as operating systems in the chemical industry . Centrifuges are machines with rotors as working spaces in which the relative concentrations in mixtures of substances can be modified. Batch operating centrifuges are particularly suitable for this purpose when high demand on quality are made with regard to separation and purity of the substances separated or when the material parameters are subject to variation. The construction permits optimum adaptation to all operating parameters. The structural components for basic and additional functions have achieved a high standard of technical maturity and some have be specified in proven DIN standards. Centrifuges are particularly suitable for use as components of combined mechanical-thermal demoisturing plants. The technology of the drive systems of centrifuges and the control systems for conducting the process and for safety purposes utilize advanced hydraulics, pneumatics and electronics. Numerous materials of construction are available, including highly corrosion-resistant metals and alloys and those bearing a corrosion-resistant protective layer. The choice and utilization of a particular structural form are determined by the specific operational behaviour on filling, washing of the filter cake residual moisture content attainable, output of solids, demoisturizing capacity, industrial hygiene aspects of sealing during demoisturization and on output, optimum arrangement of the centrifuge in the overall plant, as well as costs of acquisition, installation and operation. Safety features are of particular importance in view of the large amount of energy stored and the possibility of operating with flammable liquids. On the basis of systematic analyses of the sources of danger, constructive measures and systems have been developed for the avoidance of explosion and fire which ensure safe operation of centrifuges.     

Selbsttätige Messung und Registrierung von Kälteleistungen im Ammoniak-Kreislauf einer Ammoniak-Kälteanlage

Ohne Zusammenfassung DRP. 605690.