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Photocontrol and structural analysis of amyloid fibril formation using azobenzene and novel spiropyran photoswitches
No full textThe self-organization of amyloidogenic peptides plays a crucial role in diseases and in physiological functions. Thus, the control of this process is a powerful tool to gain insights into its kinetics and the structural nature of the peptide assemblies. In this work different photoswitches were incorporated into PTH-derived peptides to establish a model system able to switch between a fibrillary and nonfibrillar state. As switches the azobenzene photoswitch 3-((4-(aminomethyl)phenyl)diazenyl)benzoic acid was chosen and the novel spiropyran building blocks were 5’-amino-1’,3’,3’-trimethylspiro[chromene-2,2’-indoline]-6-carboxylic acid and 6-amino-1’,3’,3’-trimethylspiro[chromene-2,2’-indoline]-5’-carboxylic acid were designed, which can be incorporated into the peptide backbone. The spiropyran building are the first report of spiropyrans introduced into the backbone of peptides. The azobenzene modified peptide were used to establish a switchable amyloid forming model system
MLUH-E-160_1, Circus aeruginosus aeruginosus (Linnaeus, 1758), eggshell
No full textInventory No.: MLUH-E-160_1, Object: eggshell, Species: Circus aeruginosus aeruginosus (Linnaeus, 1758), Preservation: good preservation, Locality_loc.: Brandenburg an der Havel, Locality today: Brandenburg an der Havel, Country: GermanyCollector_leg.: G. Benke, Date: 03/05/1918, Collection_coll.: M. Schönwetter, published in Handbuch der Oologie, Schönwetter, Max: Vol. I, p. 176, Identification by: M. Schönwetter, Aquisition: 1919, Aquired from: G. Benke, ex Collection: ex. Coll. G. Benk
MLUH-E-188_1, Accipiter nisus granti Sharpe, 1890, eggshell
No full textInventory No.: MLUH-E-188_1, Object: eggshell, Species: Accipiter nisus granti Sharpe, 1890, Preservation: complete preservation, Locality_loc.: Funchal Madeira, Locality today: Funchal, Country: SpainDate: ?, Collection_coll.: M. Schönwetter, published in Handbuch der Oologie, Schönwetter, Max: Vol. I, p. 161, Identification by: M. Schönwetter, Aquisition: 1939, Aquired from: Schl., ex Collection: ex.Coll. Schl; ex. Coll. O. Bamber
MLUH-E-11_2, Falco peregrinus Tunstall, 1771, eggshell
No full textInventory No.: MLUH-E-11_2, Object: eggshell, Species: Falco peregrinus Tunstall, 1771, Preservation: complete preservation, Locality_loc.: Lehmitz (Brandenburg), Locality today: Germany, Country: GermanyCollector_leg.: Frl. H. Ickert, Date: 06/04/1919, Collection_coll.: M. Schönwetter, published in Handbuch der Oologie, Schönwetter, Max: Vol. I, p. 189, Identification by: M. Schönwetter, Aquisition: 1919, Aquired from: Frl. H. Ickert, ex Collection: ex. Coll. Frl. H. Ickert, Additional Information: Lehmitz 28km away from Berli
Efficient simulation and optimization of simulated moving bed chromatography processes
No full textChromatography is a powerful separation technique that has been used on the preparative scale in a wide range of industries, including the chemical, pharmaceutical, and food industries. It allows the separation of molecules that are temperature sensitive and/or have similar physical properties such as stereoisomers or enantiomers and are therefore difficult to separate with other types of processes. For continuous process
operation, simulated moving bed (SMB) technology was introduced by Broughton et al. in 1961 [11]. The main advantages of SMB processes compared to the classical batch processes are increased productivity and reduced solvent consumption. Since SMB processes are relatively expensive, model-based design and optimization play an important role. For this purpose, triangle theory has been developed [81]. It is based on
an idealized model, which assumes isothermal operation, and constant flow rates, axial dispersion is neglected, and thermodynamic equilibrium is assumed between the liquid and the solid phase. Further, simulated moving bed operation is approximated by the assumption of a true moving bed operated under steady-state conditions, which is valid if the number of columns is high. Under these assumptions, an analytical solution to the design problem is possible for certain classes of equilibrium relations and binary separation problems with total separation. For a moderate number of columns, incomplete separation, and/or separation problems with more than two fractions usually a numerical approach is applied. Due to the presence of sharp concentration fronts, the numerical solution is often challenging and can be computationally expensive.
In this thesis, the analytical approach is extended to the dynamic simulated moving bed model. Like the corresponding steady-state solution, It is based on the method of characteristics and first applied to processes with linear adsorption isotherms in chapter 3 of this thesis. The method is based on a discretization of the concentration coordinate instead of a discretization of the spatial coordinate, which is applied in the classical method of line approaches. Inside the columns, concentration values are propagated with characteristic velocity and new positions in space are calculated cyclically at selected time points. This method is exact for linear isotherms, the discretization of concentrations is only used for the representation of the solution and for evaluating the coupling conditions between the columns. Application is demonstrated for a binary separation in a 4-zone process and a center-cut separation in an 8-zone Simulated Moving Bed chromatography (SMB) process. In the center-cut separation, an intermediate component is isolated from a multi-component mixture. It is shown, that the computational effort can be reduced by more than a factor of 100 compared to the classical cell model which represents a first-order finite volume discretization scheme in space. In the fourth chapter, an extension to nonlinear isotherms is discussed. In the first step, a non-linear non-competitive Langmuir isotherm is considered. It is shown that the solution effort increases due to possible shock formation for non-linear isotherms. As a result of the shock formation, the method is no longer exact anymore but depends on the discretization of the concentration coordinate. Different strategies for capturing the shock formation are proposed and compared with each other in terms of accuracy and efficiency. Due to the limited applicability of the analytical approach to nonlinear isotherms, a different approach is then proposed in Chapter 5 for the optimization of SMB processes with competitive isotherms based on surrogate models. The approach is demonstrated for a binary separation process with competitive Langmuir isotherms. The method is iterative. In each iteration, artificial neural networks are fitted to the reference model based on randomly distributed sampling points around the optimal solution of the previous iteration based on the previous iteration’s results. Maximum productivity under a certain purity requirement is obtained at the end of the process. The method is particularly attractive for processes with a high number of stages but reduced product purities, where classical triangle theory cannot be applied. Such situations may arise for a given plant with highly efficient columns for applications with moderate purity requirements, where product purities can be relaxed to increase productivity. In these cases, the proposed approach is also much faster than the numerical optimization of the full model. In this thesis, the focus is on local optimization. Even higher potential for improvement by surrogate-based optimization can be expected for deterministic global optimization, which is therefore becoming more and more attractive for the optimization of complex chemical processes like SMB processes.Die Chromatographie ist ein leistungsfähiges Trennverfahren, das im präparativen Maßstab in einer Vielzahl von Industriezweigen eingesetzt wird, unter anderem in der Chemie-, Pharma- und Lebensmittelindustrie.
Sie ermöglicht die Trennung von Molekülen, die temperaturempfindlich sind und/oder ähnliche physikalische Eigenschaften haben, wie z. B. Stereoisomere oder Enantiomere, und die daher mit anderen Verfahren nur schwer zu trennen sind. Für den kontinuierlichen Prozessbetrieb wurde 1961 von Broughton et al. die Simulated-Moving-Bed-Technologie (SMB) eingeführt [11]. Die Hauptvorteile von SMB-Prozessen im Vergleich zu den klassischen Batch-Prozessen sind die höhere Produktivität und der geringere Lösungsmittelverbrauch. Da SMB-Prozesse relativ teuer sind, spielen die modellbasierte Prozessgestaltung und Optimierung eine wichtige Rolle. Zu diesem Zweck wurde die Dreiecks-Theorie entwickelt [81]. Sie basiert auf einem idealisierten Modell, das von einem isothermen Betrieb und konstanten Durchflussraten ausgeht, die axiale Dispersion vernachlässigt und thermodynamisches Gleichgewicht zwischen der festen und der flüssigen Phase annimmt. Außerdem wird an Stelle eines simulierten Gegenstromes ein echter Gegenstrom der festen Phase angenommen, was aber nur bei einer relativ hohen Anzahl von Trennsäulen eine gute Näherung darstellt. Unter diesen Annahmen ist eine analytische Lösung des Auslegungsproblems für bestimmte Klassen von Gleichgewichtsbeziehungen und binären Trennproblemen mit vollständiger Trennung möglich. Bei einer mäßigen Anzahl von Trennsäulen, unvollständiger Trennung und/oder Trennproblemen mit mehr als zwei Fraktionen wird in der Regel ein numerischer Ansatz verwendet. Aufgrund des Auftretens steiler Konzentrationsfronten ist die numerische Lösung oft eine Herausforderung und kann rechenintensiv sein. In dieser Arbeit wird der analytische Ansatz auf das dynamische Prozessmodell mit simuliertem Gegenstrom erweitert. Wie die entsprechende stationäre Lösung des idealisierten Modells mit echtem Gegenstrom basiert er auf der Methode der Charakteristiken und wird zuerst in Kapitel 3 dieser Arbeit auf Prozesse mit linearen Adsorptionsisothermen angewandt. Die Methode basiert auf einer Diskretisierung der Konzentrationskoordinate anstelle einer Diskretisierung der Raumkoordinate, wie sie bei den klassischen Linienmethoden angewendet wird. Innerhalb der Säulen wandern die Konzentrationswerte mit charakteristischer Geschwindigkeit. Zu ausgewählten Zeitpunkten werden zyklisch neue Positionen in den Säulen berechnet. Diese Methode ist exakt für lineare Isothermen. Die Diskretisierung der Konzentrationen wird nur für die graphische Darstellung der Lösung und für die Auswertung der Kopplungsbedingungen zwischen den Säulen verwendet. Die Anwendung wird für eine binäre Trennung in einem 4-Zonen-Prozess und eine so genannte Center-Cut-Trennung in einem 8-Zonen SMB-Prozess demonstriert. Bei der Center-Cut-Trennung wird eine Zwischenkomponente aus einem Mehrkomponentengemisch isoliert. Es wird gezeigt, dass der Rechenaufwand im Vergleich zum klassischen Zellenmodell, das ein Diskretisierungsschema erster Ordnung im Ort darstellt, um mehr als einen Faktor 100 reduziert werden kann. Im vierten Kapitel wird eine Erweiterung auf nichtlineare Isothermen diskutiert. In einem ersten Schritt werden nicht-lineare, nicht-kompetitive Langmuir-Isothermen betrachtet. Es wird gezeigt, dass der Lösungsaufwand aufgrund einer möglichen Schockbildung bei nichtlinearen Isothermen zunimmt. Als Folge der Schockbildung ist die Methode nicht mehr exakt, sondern hängt von der Diskretisierung der Konzentrationskoordinate ab. Es werden verschiedene Strategien zur Erfassung der Schockbildung vorgeschlagen und in Bezug auf Genauigkeit und Effizienz miteinander verglichen. Aufgrund der begrenzten Anwendbarkeit des analytischen Ansatzes auf nichtlineare Isothermen wird dann in Kapitel 5 ein alternativer Ansatz für die Optimierung von SMB-Prozessen mit konkurrierenden Isothermen auf der Grundlage von Ersatzmodellen vorgeschlagen. Der Ansatz wird für einen binären Trennungsprozess mit konkurrierenden Langmuir-Isothermen demonstriert. Die Methode ist iterativ. In jeder Iteration werden künstliche neuronale Netze an das Referenzmodell auf der Grundlage zufällig verteilter Stichprobenpunkte um die optimale Lösung der vorherigen Iteration herum angepasst. Am Ende des Verfahrens wird so die maximale Produktivität unter vorgegebenen Reinheitsanforderungen erreicht. Die Methode ist besonders attraktiv für Prozesse mit einer hohen Anzahl von Stufen, aber geringeren Produktreinheiten, bei denen die klassische Dreieckstheorie nicht angewendet werden kann. Solche Situationen können bei einer vorhandenen Anlage mit hocheffizienten Kolonnen für Anwendungen auftreten, bei denen die Produktreinheiten gelockert werden können, um die Produktivität zu erhöhen. In diesen Fällen ist der vorgeschlagene Ansatz auch viel schneller als die numerische Optimierung des vollständigen Modells. In dieser Arbeit liegt der Schwerpunkt auf der lokalen Optimierung. Ein noch höheres Verbesserungspotenzial durch surrogatbasierte Optimierung ist für die deterministische globale Optimierung zu erwarten, die daher für die Optimierung komplexer chemischer Prozesse wie SMB-Prozesse immer attraktiver wird.Literaturverzeichnis: Seite [107]-11
Leaving school : a healthy transition in late adolescence?
No full textBackground: Adolescents’ subjective well-being (SWB) is a key indicator of quality of life. While its development during schooling has been widely studied, few studies have examined changes in SWB after leaving school due to the need for longitudinal data. This study investigates changes in SWB among adolescents in Germany over the two years before and after leaving school, focusing on school type, socioeconomic position, gender, and family structure. Methods: We use data from the ninth-grade cohort of the German National Educational Panel Study, first surveyed in 2010 and followed annually. Growth modeling (specifically, a multilevel discontinuity model) is applied to analyze SWB trajectories and potential moderation by background characteristics. The final sample includes 19,767 observations from 6599 individuals. Results: SWB increases notably after leaving school and remains stable before and after the transition. The increase is smaller for adolescents completing higher secondary education, living in nuclear families, or identifying as male. These groups report higher SWB prior to the transition, so post-school changes reduce group differences. Conclusion: The findings suggest that schools may lack adequate resources to support adolescents in mastering key developmental challenges. While school is a critical environment, it may also impose pressures that are associated with lower well-being
Transient ligand contacts of the intrinsically disordered N-terminus of neuropeptide Y2 receptor regulate arrestin-3 recruitment
No full textPrevious efforts in delineating molecular mechanisms of G protein-coupled receptor (GPCR) activation have focused on transmembrane regions and ligand-receptor contacts of the extracellular loops. The role of the highly flexible N-termini of rhodopsin-like GPCRs have not been well characterized to date. We hypothesize that transient contacts between the peptide ligand and the intrinsically disordered N-terminus (NT) of the neuropeptide Y (NPY) receptor Y2 (Y2R) will affect receptor signaling. We employ cross-linking mass spectrometry to capture ligand-receptor contacts including transient binding modes. A photo-reactive NPY analogue allows mapping the interaction between NPY and Y2R NT resulting in a total number of 40 cross-links. The cross-links provide distance constraints for deriving structural models of the interaction. Molecular dynamics simulations highlight the structural flexibility and rapid interconversion of ligand-receptor contacts. Mutagenesis of Y2R and functional characterization suggest that the cross-linking hotspots in the NT electrostatically control its conformational ensemble. The NT engages in transient contacts to the peptide and prolongs ligand residence time, which is required for efficient interaction of Y2R with arrestin-3, but not Gi. We delineate structure-function relationships for the intrinsically disordered Y2R NT and propose a functional role for transient binding modes involving the NT of a peptide-binding receptor
MLUH-E-428_1, Elanus caeruleus caeruleus (Desfontaines,1789), eggshell
No full textInventory No.: MLUH-E-428_1, Object: eggshell, Species: Elanus caeruleus caeruleus (Desfontaines,1789), Preservation: complete preservation, Locality_loc.: Balgowen Natal, Locality today: Balgowan, Country: South AfricaCollector_leg.: J. A. Cottrell, Date: 01/02/1920, Collection_coll.: M. Schönwetter, published in Handbuch der Oologie, Schönwetter, Max: Vol. I, p. 154, Identification by: M. Schönwetter, Aquisition: 1930, Aquired from: Gowland, ex Collection: ex. Coll. J. A. Cottrell; ex. Coll. Gowland; ex. Coll. Wm. T. Cottrel
MLUH-E-174_5, Accipiter gentilis gentilis (Linnaeus, 1758), eggshell
No full textInventory No.: MLUH-E-174_5, Object: eggshell, Species: Accipiter gentilis gentilis (Linnaeus, 1758), Preservation: complete preservation, Locality_loc.: Burgtonnaer Holz bei Gotha, Locality today: Burgtonna, Country: GermanyCollector_leg.: O. Martin, Date: 20/04/1912, Collection_coll.: M. Schönwetter, published in Handbuch der Oologie, Schönwetter, Max: Vol. I, p. 157, Identification by: M. Schönwetter, Aquisition: 1912, Aquired from: O. Martin, ex Collection: ex. Coll. O. Marti
Extracellular RNA drives TNF-α/TNF-receptor-1 mediated cardiac ischemia/reperfusion injury : mechanistic insights and therapeutic potential of RNase1
No full textMyocardial ischemia/reperfusion (I/R) injury causes cardiomyocyte death and exacerbates inflammation. Emerging evidence implicates extracellular RNA (eRNA) and tumor necrosis factor-α (TNF-α) as key mediators. We hypothesize that eRNA released from ischemic cardiomyocytes amplifies I/R injury via TNF-α/TNF-receptor-1 (TNF-R1) signaling, and that hydrolysis of eRNA by RNase1 can attenuate I/R injury by disrupting this pathway. Here, we investigated the mechanistic role of eRNA and its interplay with TNF-α signaling in cardiac I/R injury, and evaluated the therapeutic potential of RNase1 and cyclosporine-A (CsA). In ST-segment elevation myocardial infarction patients, plasma eRNA levels were significantly elevated 2 h post-percutaneous coronary intervention (PCI), correlating positively with Creatine Kinase (CK). In murine I/R and hypoxia/reoxygenation models, eRNA released from stressed cardiomyocytes acted as a damage-associated molecular pattern, triggering TNF-α shedding via TACE/ADAM17 and activating TNF-R1-mediated inflammation, mPTP opening, and cell death. Genetic deletion of TNF-α or TNF-R1 abrogated eRNA-induced cytotoxicity, while TNF-receptor- 2 (TNF-R2) deficiency exacerbated injury. Pharmacological inhibition of TACE with TAPI suppressed TNF-α release and preserved cell viability. RNase1 effectively degraded eRNA, blocking upstream pro-inflammatory signaling, whereas CsA preserved mitochondrial integrity by preventing mPTP opening. Notably, RNase1 and CsA showed synergistic protection in vivo when administered at reperfusion, significantly reducing myocardial infarct size. These findings identify eRNA as both a biomarker and pathogenic mediator of myocardial I/R injury, and support a dual-targeted strategy using RNase1 and CsA to interrupt the TNF-α/TNF-R1-driven inflammatory and mitochondrial death pathways. Targeting both upstream inflammatory and downstream mitochondrial mechanisms represents a promising cardioprotective intervention for acute myocardial infarction