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Parawasserstoff Induzierte Hyperpolarisation an Peptiden und Miniproteinen
Get PDFDie Kernspinmagnetresonanzspektroskopie (NMR-Spektroskopie) ist eine bedeutende Technik in der modernen Analytik, vor allem in der Chemie. Darüber hinaus besitzt die NMR eine medizinische Relevanz in Form der Magnetresonanztomographie (MRT). Beide Techniken besitzen allerdings nur eine geringe Sensitivität bedingt durch die niedrigen Energieunterschiede der Kernspinniveaus und der daraus resultierenden geringen Polarisation. Verschiedene Hyperpolarisationstechniken ermöglichen die Verstärkung von NMR-Signalen in der Spektroskopie und der MRT. Die Parawasserstoffinduzierte Polarisation (PHIP) ist eine besonders einfach anwendbare, schnelle und vergleichsweise günstige Methode der Hyperpolarisation. Die Anwendung von PHIP an biologischen Molekülen ermöglicht einfachere und schnellere Untersuchungen von biologischen Prozessen und die Entwicklung neuartiger Kontrastmittel für die Medizin. Während bisher vor allem kleine Moleküle des Stoffwechsels hierfür untersucht wurden, widmet sich diese Arbeit größeren Molekülen wie Peptiden und Miniproteinen. In dieser Arbeit wird PHIP an dem Octapeptid Octreotid und dem Miniprotein MCoTI angewendet. Es wird zunächst die Synthese und der Einbau der speziellen Marker in die Biomoleküle durchgeführt und optimiert. Anschließend wird der Einfluss unterschiedlicher Positionen der Marker in den Biomolekülen auf die Effektivität von PHIP untersucht, diskutiert und ein Bezug zur biologischen Aktivität hergestellt
Beyond antibody engineering: directed evolution of alternative binding scaffolds and enzymes using yeast surface display
Get PDFPioneered exactly 20 years ago, yeast surface display (YSD) continues to take a major role in protein engineering among the high-throughput display methodologies that have been developed to date. The classical yeast display technology relies on tethering an engineered protein to the cell wall by genetic fusion to one subunit of a dimeric yeast-mating agglutination receptor complex. This method enables an efficient genotype–phenotype linkage while exploiting the benefits of a eukaryotic expression machinery. Over the past two decades, a plethora of protein engineering efforts encompassing conventional antibody Fab and scFv fragments have been reported. In this review, we will focus on the versatility of YSD beyond conventional antibody engineering and, instead, place the focus on alternative scaffold proteins and enzymes which have successfully been tailored for purpose with regard to improving binding, activity or specificity
Extrem neutronenreicher Sauerstoffkern: Erstmalige Erzeugung von ²⁸O
Get PDFEinem internationalen Forschungsteam ist es gelungen, den neutronenreichsten Sauerstoff Kern ²⁸O mit 20 Neutronen an der Forschungsanlage RIKEN in Japan zu erzeugen. Dies gibt entscheidende Einblicke in die starke Wechselwirkung unter den neutronenreichsten Bedingungen, die im Labor erreicht werden können. Diese wichtigen Tests der starken Wechselwirkung erlauben es, verlässliche Vorhersagen für neutronenreiche Materie in Neutronensternen zu entwickeln
Boosting Coercivity of 3D Printed Hard Magnets through Nano‐Modification of the Powder Feedstock
Get PDFThe demand for strong, compact permanent magnets essential for the energy transition drives innovation in magnet manufacturing. Additive manufacturing, particularly Powder Bed Fusion of metals using a laser beam (PBF‐LB/M), offers potential for near‐net‐shaped Nd‐Fe‐B permanent magnets but often falls short compared to conventional methods. A less explored strategy to enhance these magnets is feedstock modification with nanoparticles. It is demonstrated that modifying a Nd‐Fe‐B‐based feedstock with 1 wt.% Ag nanoparticles boost the coercivity of the magnets to a record value of 935 ± 6 kA m⁻¹ without further post‐processing or heat treatments. Suitable volumetric energy densities for the PBF‐LB/M process are determined using finite element simulations predicting melt pool behavior and part density. Microstructural analyses reveal finer grain sizes and more equiaxed nanocrystalline structures due to the modification. Atom probe tomography identifies three phases in the Ag‐modified samples, with Ag forming nanophase regions with rare‐earth elements near the amorphous Zr‐Ti‐B‐rich intergranular phase, potentially decoupling the Nd2Fe14B primary phase. The study shows that superior magnetic properties primarily result from microstructure modification rather than part density. These findings highlight inventive material design approaches via feedstock surface modification to achieve superior magnetic performance in additively manufactured Nd‐Fe‐B magnets
Self-decorating cells via surface-initiated enzymatic controlled radical polymerization
Get PDFThrough the innovative use of surface-displayed horseradish peroxidase, this work explores the enzymatic catalysis of both bioRAFT polymerization and bioATRP to prompt polymer synthesis on the surface of Saccharomyces cerevisiae cells, with bioATRP outperforming bioRAFT polymerization. The resulting surface modification of living yeast cells with synthetic polymers allows for a significant change in yeast phenotype, including growth profile, aggregation characteristics, and conjugation of non-native enzymes to the clickable polymers on the cell surface, opening new avenues in bioorthogonal cell-surface engineering
Character Shifts in Harry Potter Fanfiction
Get PDFIn fanfictions, authors can explore the fictitious universe of a fandom without restricting themselves to its canonical rules and orders. These explorations are often linked to diverging character conceptualizations based on readers’ response to omissions and indeterminacies in the source material. Following a three part structure, we examine these character shifts in German Harry Potter fanfictions by (1) comparing basic frequency distributions of character names, (2) analyzing character co-occurrences in order to identify central character pairings as well as collocations surrounding these characters, and (3) using a word embedding-based approach to sentiment analysis to quantify the emotional charging of characters. We identified certain character types predestined for re-conceptualization, such as minor characters or figures from pre- or sequels who generate interest among fanfiction writers, as well as villainous characters whose redesign follows typical fanfiction tropes such as »Enemies to Lovers«
Automation architecture for harnessing the demand response potential of aqueous parts cleaning machines
Get PDFTo reduce global greenhouse gas emissions, numerous new renewable power plants are installed and integrated in the power grid. Due to the volatile generation of renewable power plants large storage capacity has to be installed and electrical consumer must adapt to periods with more or less electrical generation. Industry, as one of the largest global consumers of electrical energy, can help by adjusting its electricity consumption to renewable production (demand response). Industrial aqueous parts cleaning machines offer a great potential for demand response as they often have inherent energy storage potential and their process can be adapted for energy-flexible operation. Therefore, this paper presents a method for implementing demand response measures to aqueous parts cleaning machines. We first determine the potential for shifting electrical consumption. Then, we adapt the automation program of the machine so that submodules and process steps with high potential can be energy-flexibly controlled. We apply the method to an aqueous parts cleaning machine in batch process at the ETA Research Factory
Determination of alpha factors for monitoring of aeration systems with the ex situ off-gas method: experience from practical application and estimation of measurement uncertainty
Get PDFPerformance of aeration systems in wastewater treatment plants (WWTP) under process conditions can be monitored with off-gas tests. The ex situ off-gas method transfers activated sludge from an adjacent aeration tank into aerated columns to determine oxygen transfer parameters (e.g., the α-factor). This method is an alternative to in situ off-gas testing with hoods at the tank surface; however, its application and measurement uncertainty have not been examined yet. We outline our experience from long-term off-gas testing with two pilot-scale test reactors (8.3 m³ volume). Global variance-based sensitivity analysis using Sobol’ indices revealed oxygen concentration in off-gas and dissolved oxygen as the most important input quantities to determine α-factors accurately. Measurement uncertainty of other instruments was negligible. These findings are transferable to in situ off-gas hoods because the methods are similar. Random measurement error of α-factors was estimated with uncertainty analysis and comparison measurements to a relative standard deviation of about ± 2.8% for our ex situ pilot setup. Diffuser fouling, biofilm growth, or sensor drift caused systematic errors avoidable by maintenance. Additional mixing of bubble column due to sludge inflow into ex situ tanks led to a systematic overestimation of α-factors at lower airflow rates. Hence, the ex situ off-gas method is not suitable to determine α-factors for the design of aeration systems but offers unique possibilities for research of oxygen transfer dynamics and development of aeration equipment because ex situ columns can be operated independently from a full-scale activated sludge tank
Embedding short-range correlations in relativistic density functionals through quasi-deuterons
Get PDFThe formation of clusters at sub-saturation densities, as a result of many-body correlations, constitutes an essential feature for a reliable modelization of the nuclear matter equation of state (EoS). Phenomenological models that make use of energy density functionals (EDFs) offer a convenient approach to account for the presence of these bound states of nucleons when introduced as additional degrees of freedom. However, in these models clusters dissolve, by construction, when the nuclear saturation density is approached from below, revealing inconsistencies with recent findings that evidence the existence of short-range correlations (SRCs) even at larger densities. The idea of this work is to incorporate SRCs in established models for the EoS, in light of the importance of these features for the description of heavy-ion collisions, nuclear structure and in the astrophysical context. Our aim is to describe SRCs at supra-saturation densities by using effective quasi-clusters immersed in dense matter as a surrogate for correlations, in a regime where cluster dissolution is usually predicted in phenomenological models. Within the EDF framework, we explore a novel approach to embed SRCs within a relativistic mean-field model with density dependent couplings through the introduction of suitable in-medium modifications of the cluster properties, in particular their binding energy shifts, which are responsible for describing the cluster dissolution. As a first exploratory step, the example of a quasi-deuteron within the generalized relativistic density functional approach is investigated. The zero temperature case is examined, where the deuteron fraction is given by the density of a boson condensate. For the first time, suitable parameterizations of the cluster mass shift at zero temperature are derived for all baryon densities. They are constrained by experimental results for the effective deuteron fraction in nuclear matter near saturation and by microscopic many-body calculations in the low-density limit. A proper description of well-constrained nuclear matter quantities at saturation is kept through a refit of the nucleon meson coupling strengths. The proposed parameterizations allow to also determine the density dependence of the quasi-deuteron mass fraction at arbitrary isospin asymmetries. The strength of the deuteron-meson couplings is assessed to be of crucial importance. Novel effects on some thermodynamic quantities, such as the matter incompressibility, the symmetry energy and its slope, are finally discerned and discussed. The findings of the present study represent a first step to improve the description of nuclear matter and its EoS at supra-saturation densities in EDFs by considering correlations in an effective way. In a next step, the single-particle momentum distributions in nuclear matter can be explored using proper wave functions of the quasi-deuteron in the medium. The momentum distributions are expected to exhibit a high-momentum tail, as observed in the experimental study of SRCs by nucleon knockout with high-energy electrons. This will be studied in a forthcoming publication with an extensive presentation of the theoretical method and the results
Work from Home Success: Agile work characteristics and the Mediating Effect of supportive HRM
Get PDFWork from home or teleworking, continues to expand not least due to the COVID-19-crisis and poses challenges for employees and companies. In uncertain and dynamic times, organisations wonder what skills make employees successful when working from home and which measures support employees. By performing in-depth research that addresses employee agility as skills and capabilities, a research framework is proposed. Based on an international survey of employees working from home during the COVID-19-crisis (N = 1,016), the impact of agile work characteristics on work from home success and the mediating effect (accounting for 48% of the total effect) of tailored support measures by HRM were investigated. The results of the mediation analysis show that agile work characteristics have a direct, positive and significant effect on the success of working from home. Part of the effect is explained by HRM measures as a mediator. The findings contribute to the research stream of dynamic capabilities by applying the theory to working from home. The comparatively simple research model provides companies with information on how they can best support employees in the dynamics of a crisis and the expansion of work from home and, therefore, has high relevance for practitioners