Development of a qualitative test method for the cleanability of polymer woven filter media

In this paper a new method for cleaning of filter media is presented, and the cleanability with different textures and surface finishes is compared. With the method described, it is possible to evaluate the quality of the cleaning process. According to the German VDMA standard cleaning test, riboflavin and malt extract are applied as model contaminants for evaluation of the cleaning results. To compare the cleanability of filter media with different properties and geometries the results are adapted to the law of mass transfer and to the Sherwood number, a dimensionless parameter describing the quality of a cleaning process.     

Digitising Teaching and Learning – Additional Perspectives for Chemistry Education

Chemistry requires and combines both observable and mental representations. Still we know that learners often struggle in combining these perspectives successfully, especially when experimental observations contradict the model‐based explanations, e. g. in interpreting the chemical equilibrium as dynamic processes while observing a static system without any visible changes. Digital media offer potentials that might not have been accessible to this degree until now. However, we do not know enough with regard to the degree and effects these media tools have in supporting learning processes but perhaps also in hindering them. This article presents four approaches on how to potentially make use of digital media in learning processes based on theoretical considerations and empirical investigations. The projects will explore applications of media as visualization, learning and investigation tools in chemistry education, embracing techniques from virtual realities to eye‐tracking.     

Preparative Protein Crystallization

Preparative protein crystallization can possibly replace one or more chromatographic steps in downstream processing. The development of such crystallization processes is demanding: first, promising principal crystallization conditions must be identified; second, details about the process must be defined; and third, the crystals have to be separated from the mother liquor without putting harm of their crystalline integrity. State‐of‐the‐art about these three steps is developing fast by (i) employing new screening methods which are based on fundamental understanding of the interaction of the protein molecules, (ii) application of existing concepts of technical bulk crystallization of small molecules to preparative protein crystallization, and (iii) making available specific gentle separation machinery.     

Cervid Prion Protein Polymorphisms: Role in Chronic Wasting Disease Pathogenesis

Chronic wasting disease (CWD) is a prion disease found in both free-ranging and farmed cervids. Susceptibility of these animals to CWD is governed by various exogenous and endogenous factors. Past studies have demonstrated that polymorphisms within the prion protein (PrP) sequence itself affect an animal’s susceptibility to CWD. PrP polymorphisms can modulate CWD pathogenesis in two ways: the ability of the endogenous prion protein (PrP^C) to convert into infectious prions (PrP^Sc) or it can give rise to novel prion strains. In vivo studies in susceptible cervids, complemented by studies in transgenic mice expressing the corresponding cervid PrP sequence, show that each polymorphism has distinct effects on both PrP^C and PrP^Sc. It is not entirely clear how these polymorphisms are responsible for these effects, but in vitro studies suggest they play a role in modifying PrP epitopes crucial for PrP^C to PrP^Sc conversion and determining PrP^C stability. PrP polymorphisms are unique to one or two cervid species and most confer a certain degree of reduced susceptibility to CWD. However, to date, there are no reports of polymorphic cervid PrP alleles providing absolute resistance to CWD. Studies on polymorphisms have focused on those found in CWD-endemic areas, with the hope that understanding the role of an animal’s genetics in CWD can help to predict, contain, or prevent transmission of CWD.     

Evaluation of real-time PCR results at the limit of detection

Real-time polymerase chain reaction (real-time PCR) facilitates to detect DNA fragments at very low copy numbers. Positive results, e.g. for unauthorized genetically modified organism (GMO) contamination or for allergens, may raise safety concerns and have far-reaching consequences. However, in case of very low concentrations of DNA samples, results for the same product lot or even for identical samples from different laboratories may differ. Therefore, an approach for a standardized interpretation and reporting of results obtained by real-time PCR at the limit of detection (LOD) is proposed. A quality control DNA sample containing the target at the LOD (95?%) is analysed in parallel with the real DNA sample and the respective C _T values are compared. In addition, practical approaches for in house and precision-based estimation of the LOD are presented. The proposed approach may also contribute to the current discussion on implementing a technical solution to handle DNA traces in specimen, e.g. for the detection of unauthorized GMO.     

High-tensile bolts without heat treatment

According to DIN-ISO 898-1 high tensile bolts of class 8.8 must have a quenched and tempered structure. Therefore either quenched and tempered wire rod is used for cold heading or the bolts are quenched and tempered after the bolt forming process. This paper presents a new wire rod, which offers the chance to get comparable or even better final properties and lower production costs: a low-carbon MnSi wire rod is used as basic material. The final tensile strength is produced by drawing and cold forming. The conventional final quenching and tempering is omitted and for many cases also baking can be avoided. An increased fatigue resistance and the elimination of final straightening of the bolts are additional advantages of the new process.     

Einlaufverhalten nasslaufender Lamellenkupplungen im Schlupfbetrieb

Forschung im Ingenieurwesen - Nasslaufende Lamellenkupplungen weisen zu Betriebsbeginn eine Phase des Einlaufens auf, in der sich das Reibungsverhalten durch Anpassung der Reibflächen...     

Microflow-based control of near-wall fluctuations for large viscous drag reduction

The stabilizing effect of microgroove surface morphology on viscous drag reduction was studied experimentally in the inlet region of a plane channel flow. The stabilization is thought to be due to the ability of a microgrooved surface pattern to suppress the velocity fluctuations in the spanwise direction on a restricted portion of the wetted surface, which prevents vorticity development at the wall and consequently across the entire flow field. This smart microflow control strategy, which works successfully only under very particular circumstances, was implemented in a microgroove-modified channel flow in which the front part has a microgrooved surface topology. The results of pressure drop measurements indicate that microgrooved surfaces can effectively stabilize laminar boundary layer development, leading to a significant reduction in the viscous drag. In the rear flat part of the microgroove-modified channel test section, a maximum drag reduction of DR @ 35%{\rm DR\simeq 35\%} was measured. This corresponds to an overall drag reduction of DR @ 16%{\rm DR\simeq 16\%} at a length Reynolds number of Re_x @ 10⁶.Re_x\simeq 10^6. The drag reduction effect persisted in a narrow range of flow velocities and for the reported experimental conditions corresponds to microgroove dimensions between 1.5 and 2.5 viscous length-scales.