Investigation of the biophysical basis for cell organelle morphology

It is known that fission yeast Schizosaccharomyces pombe maintains its nuclear envelope during mitosis and it undergoes an interesting shape change during cell division - from a spherical via an ellipsoidal and a peanut-like to a dumb-bell shape. However, the biomechanical system behind this amazing transformation is still not understood. What we know is, that the shape must change due to forces acting on the membrane surrounding the nucleus and the microtubule based mitotic spindle is thought to play a key role. To estimate the locations and directions of the forces, the shape of the nucleus was recorded by confocal light microscopy. But such data is often inhomogeneously labeled with gaps in the boundary, making classical segmentation impractical. In order to accurately determine the shape we developed a global parametric shape description method, based on a Fourier coordinate expansion. The method implicitly assumes a closed and smooth surface. We will calculate the geometrical properties of the 2-dimensional shape and extend it to 3-dimensional properties, assuming rotational symmetry. Using a mechanical model for the lipid bilayer and the so called Helfrich-Canham free energy we want to calculate the minimum energy shape while respecting system-specific constraints to the surface and the enclosed volume. Comparing it with the observed shape leads to the forces. This provides the needed research tools to study forces based on images

Concept for modelling the influence of electrode corrugation after calendering on stacking accuracy in battery cell production

Due to the complex process chain in battery cell production, effects of processes on subsequent processes must be evaluated. As challenge in calendering electrodes, corrugation can be observed depending on adjusted parameters. To evaluate the corrugation with regard to the subsequent stacking process accuracy, a concept for modelling the process chain calendering - separation - single sheet stacking is presented. First, an experimental approach for modelling the calendering impact on the electrode sheet geometry after separation is suggested. Finally, a FEM simulation approach for the single sheet stacking process is presented, which is suitable to model impacts from previous processes

Comparison of geranylgeranyl and phytyl substituted methylquinols in the tocopherol synthesis of spinach chloroplasts

Geranylgeranyl substituted methylquinols are shown to be precursors of tocopherol biosynthesis in spinach chloroplasts as well as phytyl substituted ones. The geranylgeranyl substituted quinols are methylated even to a greater extent than the phytyl substituted ones. The connection to the so far known biosynthetic origin of -tocopherol is probably -tocotrienol which is hydrogenated to γ-tocopherol and then further methylated to -tocopherol

Influence of electrode corrugation after calendering on the geometry of single electrode sheets in battery cell production

Calendering is an essential process step in battery cell production. By selective compaction of the material, the performance of the battery cell can be optimized. During processing, corrugations can occur in the machine direction, which are characterized in this article in relation to the material systems LiNi$_{0.8}$Mn$_{0.1}$Co$_{0.1}$O$_2$ (NMC811) and LiNi$_{0.6}$Mn$_{0.2}$Co$_{0.2}$O$_2$ (NMC622) as well as the rate of compaction and the web tension. It is shown that the corrugations are strongly dependent on the rate of compaction. The material system and the web tension show a weaker influence on the corrugation characteristics. Subsequently, single electrode sheets are cut from the coils and their geometry is investigated. It is shown that the corrugation hardly propagates further into the single electrodes, which is explained with the storage time of the electrodes. Rather, the coil bending strongly influences the electrode sheet geometry. It is shown that the position of the conductor tab also has an important influence

The perfect crime? : CCSVI not leaving a trace in MS

Background: Multiple sclerosis (MS) is a chronic, inflammatory demyelinating disease of the central nervous system, believed to be triggered by an autoimmune reaction to myelin. Recently, a fundamentally different pathomechanism termed ‘chronic cerebrospinal venous insufficiency’ (CCSVI) was proposed, provoking significant attention in the media and scientific community. Methods: Twenty MS patients (mean age 42.2±13.3 years; median Extended Disability Status Scale 3.0, range 0–6.5) were compared with 20 healthy controls. Extra- and intracranial venous flow direction was assessed by colour-coded duplex sonography, and extracranial venous cross-sectional area (VCSA) of the internal jugular and vertebral veins (IJV/VV) was measured in B-mode to assess the five previously proposed CCSVI criteria. IJV-VCSA≤0.3 cm2 indicated ‘stenosis,’ and IJV-VCSA decrease from supine to upright position ‘reverted postural control.’ The sonographer, data analyser and statistician were blinded to the patient/control status of the participants. Results: No participant showed retrograde flow of cervical or intracranial veins. IJV-VCSA≤0.3 cm2 was found in 13 MS patients versus 16 controls (p=0.48). A decrease in IJV-VCSA from supine to upright position was observed in all participants, but this denotes a physiological finding. No MS patient and one control had undetectable IJV flow despite deep inspiration (p=0.49). Only one healthy control and no MS patients fulfilled at least two criteria for CCSVI. Conclusions: This triple-blinded extra- and transcranial duplex sonographic assessment of cervical and cerebral veins does not provide supportive evidence for the presence of CCSVI in MS patients. The findings cast serious doubt on the concept of CCSVI in MS

Wie arbeiten Schüler in den naturwissenschaftlichen Fächern ? : Lernforschung in der Schule und im Schülerlabor Biologie als Grundlage zukünftiger Schulentwicklung

Wissenschaftsmethodische Kompetenzen und ein wissenschaftstheoretisches Verständnis der Naturwissenschaften sind Teil einer naturwissenschaftlichen Bildung. Ob Schülerinnen und Schüler diese Kompetenzen bis zum Ende ihrer Schullaufbahn überhaupt entwickeln ist aber weitgehend unbekannt. Am Institut für Biologiedidaktik arbeitet seit 2001 die Arbeitsgruppe „Wissenschaftliche Arbeitsweisen im Biologieunterricht“ an dem Ziel, aus der Sicht der Fachdidaktik Biologie grundlegende Variablen des naturwissenschaftlichen Arbeitsprozesses bei Schülern zu identifizieren, modellhaft abzubilden und theoretisch zu fassen. Ein wichtiges Instrument war dabei – neben der Feldforschung – die Einrichtung eines Schüler-Labors zur Erforschung von Schülergruppen unter standardisierten Bedingungen

Biodiversitätsforschung als Zukunftsdisziplin : Ein Beitrag der Biologiedidaktik

Die biologische Vielfalt ist ein Charakteristikum der belebten Natur. Unter dem Begriff der Biodiversität erfährt sie derzeit innerhalb der Biologie, der Ökonomie und der Politik eine zunehmende Wertschätzung. So wurde ihre Erhaltung und nachhaltige Nutzung in der Rio-Konvention zum ‘Schutz der Biodiversität’ international festgelegt. Zur Umsetzung dieser Konvention sind Initiativen des Staates, der Wirtschaft, der Forschung und der Bildung gefordert. Die Beteiligung der Humanwissenschaften ist dabei unabdingbar, denn die Interaktion des Menschen mit seiner Umwelt ist einerseits die Quelle der Umweltprobleme, andererseits der Schlüssel zu ihrer Lösung. Im Fokus der Biologiedidaktik steht dabei die Frage, wie Kinder und Jugendliche durch Lehr-Lernprozesse befähigt und motiviert werden können, ihre Verantwortung im Bereich individuellen un

2-Methyl-6-phytylquinol and 2,3-dimethyl-5-phytylquinol as precursors of tocopherol synthesis in spinach chloroplasts

The incorporation of [Me-14C] from SAM-[Me-14C] into precursors indicates the following sequence of tocopherol synthesis in spinach: 2-methyl-6-phytylquinol (6-phytyltoluquinol) (1a) → 2,3-dimethyl-5-phytylquinol (phytylplastoquinol) (2a)→,γ-tocopherol (5a)→-tocopherol (6). 1a is particularly preferred to 2-methyl-5-phytylquinol (1b) and 2-methyl-3-phytylquinol (1c). 1a only forms 2a. 2a is converted to 6 via 5a and, to a lesser extent, 2,5-dimethyl-6-phylquinol (2b) to 6 via β-tocopherol (5b). Trimethylphytylquinol (3) is not an intermediate in the formation of 6. All reactions are independent of light

Using bacterial biomarkers to identify early indicators of cystic fibrosis pulmonary exacerbation onset

Acute periods of pulmonary exacerbation are the single most important cause of morbidity in cystic fibrosis patients, and may be associated with a loss of lung function. Intervening prior to the onset of a substantially increased inflammatory response may limit the associated damage to the airways. While a number of biomarker assays based on inflammatory markers have been developed, providing useful and important measures of disease during these periods, such factors are typically only elevated once the process of exacerbation has been initiated. Identifying biomarkers that can predict the onset of pulmonary exacerbation at an early stage would provide an opportunity to intervene before the establishment of a substantial immune response, with major implications for the advancement of cystic fibrosis care. The precise triggers of pulmonary exacerbation remain to be determined; however, the majority of models relate to the activity of microbes present in the patient's lower airways of cystic fibrosis. Advances in diagnostic microbiology now allow for the examination of these complex systems at a level likely to identify factors on which biomarker assays can be based. In this article, we discuss key considerations in the design and testing of assays that could predict pulmonary exacerbations

Model‐Based Optimization of Web Tension Control for the Flexible Cell Stack Assembly of Lithium‐Ion Battery Cells

The transformation toward electromobility presents a significant challenge to the battery cell production processes. It is, therefore, necessary to establish efficient and robust operations and machines to meet the forecasted demand for manufactured cell capacity. Currently, the development and ramp-up phases of production machines, especially for cell stack assembly, are characterized by high material scrap rates and large personnel expenses. Aspects such as the web tension of electrodes or separator materials during separation and stack assembly have a significant influence on the subsequent intermediate product properties, and therefore present a key challenge. Herein, the optimal methodology for the web tension control of electrode materials is determined via a model-based approach by the means of a digital twin. The focus is hereby set on a production machine for the flexible cell stack assembly. Appropriate control methods are implemented and validated on the real system, thus reducing material scrap rates and overall costs. The control of the web tension by means of an unwinder and material storage was found to be optimal on the basis of the model and confirmed experimentally