Elastohydrodynamic Simulation of Pneumatic Sealing Friction Considering 3D Surface Topography

This contribution presents an elastohydrodynamic lubrication (EHL) model for pneumatic spool valves. For an accurate estimation of the transient friction of this tribological sealing system, the surface topography of the cylindrical sealing counterfaces of the valve housings are measured and analyzed with an optical surface measurement instrument. Based on the surface topography data, tribological properties and flow factors of the system are derived. It has been found that the consideration of the surface topography has a significant influence on the simulation results of the EHL model, lowering the calculated friction force by up to 20 %.     

Engineered Platelet-Derived Growth Factor-Releasing Hydrogels Promote Fetal Membrane Healing In Vivo

Fetoscopic interventions to treat fetal anomalies are currently performed for a variety of conditions. Depending on the procedure, preterm rupture of the fetal membranes (FMs) happens in around 30% of the cases, potentially leading to preterm birth and fetal morbidity and mortality. Here, the capacity of modular transglutaminase crosslinked poly(ethylene glycol) (TG-PEG) hydrogels that release platelet-derived growth factor (PDGF)-BB to promote FM healing is described. In vitro, such growth factor-loaded hydrogels are able to stimulate amniotic cell migration and proliferation. When applied in vivo, these TG-PEG hydrogels tightly seal the FM and uterus defects created by a fetoscope and remain stable for 10 days. The migration of healing-related cells into such hydrogels in the myometrium, endometrium, and FM areas is only possible in soft TG-PEG hydrogels. Importantly, bioengineered hydrogels releasing PDGF-BB promote recruitment of host cells from the myometrium and the endometrium, and to a lesser extent from FM areas. In such hydrogels, the potent proliferation and matrix production of the recruited cells at the site of treatment into the biomaterial initiates a robust early healing response. PDGF-BB-loaded TG-PEG hydrogels hold great promise for the treatment of fetoscopy-induced FM defects and for the prevention of preterm birth.     

Myxococcus xanthus as Host for the Production of Benzoxazoles

Benzoxazoles are important structural motifs in pharmaceutical drugs. Here, we present the heterologous production of 3-hydroxyanthranilate-derived benzoxazoles in the host bacterium Myxococcus xanthus following the expression of two genes from the nataxazole biosynthetic gene cluster of Streptomyces sp. Tü 6176. The M. xanthus expression strain achieved a benzoxazole titer of 114.6±7.4 mg L⁻¹ upon precursor supplementation, which is superior to other bacterial production systems. Crosstalk between the heterologously expressed benzoxazole pathway and the endogenous myxochelin pathway led to the combinatorial biosynthesis of benzoxazoles featuring a 2,3-dihydroxybenzoic acid (2,3-DHBA) building block. Subsequent in vitro studies confirmed that this crosstalk is not only due to the availability of 2,3-DHBA in M. xanthus, rather, it is promoted by the adenylating enzyme MxcE from the myxochelin pathway, which contributes to the activation of aryl carboxylic acids and delivers them to benzoxazole biosynthesis.     

Nanoscale Control of the Surface Functionality of Polymeric 2D Materials

Typically, 2D nanosheets have a homogeneous surface, making them a major challenge to structure. This study proposes a novel concept of 2D organic nanosheets with a heterogeneously functionalized surface. This work achieves this by consecutively crystallizing two precisely synthesized polymers with different functional groups in the polymer backbone in a two-step process. First, the core platelet is formed and then the second polymer is crystallized around it. As a result, the central area of the platelets has a different surface functionality than the periphery. This concept offers two advantages: the resulting polymeric 2D platelets are stable in dispersion, which simplifies further processing and makes both crystal surfaces accessible for subsequent functionalization. Additionally, a wide variety of polymers can be used, making the process and the choice of surface functionalization very flexible.     

Dynamic Friction Model for the Investigation of Stick-Slip Oscillations

The optimization of lubricated sealing systems with respect to the stick-slip effect requires a friction model that describes the complex friction behavior in the lubricated contact area. This paper presents an efficient dynamic friction model based on the Stribeck curve, which allows to investigate the influencing parameters through finite element (FE) simulations. The simulation of a tribometer test using this friction model proofs that the model correlates well with the tribometer test results. It is shown that the system stiffness has a significant influence on the stick-slip tendency of the system.     

Investigations on the allergenicity of gluten and hydrolyzed wheat proteins in wheat-dependent exercise-induced anaphylaxis

In the spectrum of wheat-related disorders, WDEIA is defined as immediate type-1 allergy. It is rare, but potentially life-threatening and caused by the exposition to wheat proteins and the presence of one or more cofactors. Patients suffer from anaphylactic reactions affecting the gastrointestinal and respiratory tracts, the skin and the cardiovascolar system with different severity. GPT, the storage proteins of wheat, are the most commonly reported WDEIA allergens. Thereby, the ω5-gliadins are known as major allergens and the HMW-GS as minor allergens. Reactions to other GPT and HWP are also reported. The golden standard to diagnose WDEIA is still an OFC, which puts patients at risk of anaphylaxis. The aim of this work was to further investigate the allergenicity of gluten and HWP in the context of WDEIA to contribute to a better understanding of the underlying mechanisms and expand diagnostic possibilities. First gluten and HWP were comparatively characterized (SDS-PAGE, content of free ammonium and RP-/GP-HPLC). Based on the results, products were selected from which ATS were prepared in order to investigate the BAT-FACS as a possible alternative diagnostic tool. Thereby, anti- CCR3-PE-mAb (BG identification marker) and anti-CD63-FITC-mAb (BG activation marker) were used. Second, patient studies with control subjects were carried out. The results showed that the BAT-FACS is very promising to supplement WDEIA routine diagnosis, as especially the ATS from ω5-gladins and sHWP showed very good test sensitivity and specificity. Individual senzitization profiles of the patients were generated after isolation of single GPT and their application as ATS in the BAT-FACS study. Gluten from a wheat/rye translocation line (G-ω5, 89% reduced content of ω5-gliadins in comparison to representative gluten G) was also applied in the BAT-FACS study to evaluate whether this could possibly be used as a hypoallergenic food. However, allergenic basophil activations in patients were documented, consequently this product is not recommended as hypoallergenic food for WDEIA patients. Our findings still leave a wheat-free diet and/or avoidance of cofactors as the only safe option for WDEIA patients. Further on, fast and easily preparable ATS, usable in clinical routine diagnosis where elaborate preparations are unwanted, were generated and sucessfully tested on patients and controls. Thereby, a detailed characterization of the contained proteins in the ATS was performed (SDS-PAGE, RP-/GP-HPLC and proteomics-based untargeted high-resolution UPLC-TripleTOF-MS). These results together with the determined BAT results indicated that non-gluten proteins are also relevant allergens in the context of WDEIA since high percentages of ATIs were determined in the ATS (G, G-ω5, sHWP). In addition, yet unidentified allergenic epitopes need to be present in the fast preparable ATS (G, G-ω5, sHWP, eHWP) because the identified proteins were searched for known WDEIA epitopes and only one epitope was found. Consequently, the known epitopes cannot explain the allergenic basophil activations triggered by these ATS in WDEIA patients. Innerhalb des Spektrums der weizenbedingten Erkrankungen wird die WDEIA als unmittelbare Typ-1- Allergie definiert. Sie ist selten, aber potenziell lebensbedrohlich und wird durch die Exposition gegenüber Weizenproteinen und das Vorhandensein eines oder mehrerer Kofaktoren verursacht. Die Patienten leiden unter anaphylaktischen Reaktionen, die den Magen-Darm-Trakt, die Atemwege, die Haut und das kardiovaskuläre System in unterschiedlichem Ausmaß betreffen. Glutenprotein Typen (GPT), die Speicherproteine des Weizens, sind die am häufigsten beschriebenen WDEIA-Allergene. Dabei sind die ω5-Gliadine als Hauptallergene und die HMW-GS als Nebenallergene bekannt. Es wird auch über Reaktionen auf andere GPT und hydrolysiertes Weizenprotein (HWP) berichtet. Der goldene Standard für die WDEIA Diagnose ist nach wie vor eine orale Provokationstestung mit dem verursachenden Lebensmittel oder Gluten, die die Patienten dem Risiko einer Anaphylaxie aussetzt. Ziel dieser Arbeit war es, die Allergenität von Gluten und HWP im Kontext der WDEIA zu untersuchen, um zu einem besseren Verständnis der zugrunde liegenden Mechanismen und Erweiterung der diagnostischen Möglichkeiten beizutragen. Zum einen wurden Gluten und HWP vergleichend charakterisiert (SDS-PAGE, Gehalt an freiem Ammonium und RP-/GP-HPLC). Auf dieser Grundlage wurden Produkte ausgewählt, aus denen allergene Testlösungen (ATS) hergestellt wurden, um den basophilen Aktivierungstest kombiniert mit fluoreszenz-aktivierter Zellsortierung (BATFACS) als alternative Diagnosemöglichkeit für WDEIA zu untersuchen. Dabei wurden Anti-CCR3-phycoerythrin- monoklonale Antikörper (Identifikationsmarker für Basophile Granulozyten) und Anti-CD63- Fluoresceinisothiocyanat-monoklonale Antikörper (Aktivierungsmarker für Basophile Granulozyten) verwendet. Es wurden anschließend Patientenstudien mit Kontrollpersonen durchgeführt. Die Ergebnisse zeigten, dass der BAT-FACS eine vielversprechende Ergänzung zur Routinediagnostik der WDEIA darstellt, da insbesondere die ATS aus ω5-Gladinen und je sHWP je eine sehr gute Testsensitivität und -spezifität aufwiesen. Durch die Isolierung einzelner GPT und deren Verwendung als ATS in der BAT-FACS-Studie wurden individuelle Sensibilisierungsprofile der Patienten erstellt. Gluten aus einer Weizen/Roggen-Translokationslinie (G-ω5, 89% reduzierter Gehalt an ω5-Gliadinen im Vergleich zu repräsentativem Gluten G) wurde ebenfalls in der BAT-FACS-Studie eingesetzt, um zu evaluieren, ob dies möglicherweise als hypoallergenes Lebensmittel verwendet werden könnte. Es wurden jedoch allergene basophile Aktivierungen bei Patienten dokumentiert, so dass dieses Produkt nicht als hypoallergenes Lebensmittel für WDEIA-Patienten zu empfehlen ist. Unsere Ergebnisse zeigen, dass eine weizenfreie Ernährung und/oder die Vermeidung von Kofaktoren die einzige sichere Option für WDEIA-Patienten ist. Weiterhin wurden schnelle und einfach zuzubereitende ATS generiert, die in der klinischen Routinediagnostik eingesetzt werden können, wo aufwendige Zubereitungen unerwünscht sind. Diese ATS wurden erfolgreich an Patienten und Kontrollen getestet. Dabei wurde eine detaillierte Charakterisierung der in den ATS enthaltenen Proteine durchgeführt (SDS-PAGE, RP- /GP-HPLC und Proteom-basierte nicht-zielgerichtete hochauflösende UPLC-TripleTOF-MS). Diese Ergebnisse deuten zusammen mit den ermittelten BAT-FACS Ergebnissen darauf hin, dass auch NichtGluten-Proteine relevante Allergene im Rahmen der WDEIA sind, da hohe Mengen an α-Amylase- Trypsin-Inhibitoren in den ATS bestimmt wurden (G, G-ω5, sHWP). Darüber hinaus zeigte sich, dass in den einfach-herstellbaren ATS (G, G-ω5, sHWP, eHWP) nicht identifizierte allergene Epitope vorhanden sein müssen, da die identifizierten Proteine auf bekannte WDEIA-Epitopen analysiert wurden und lediglich eines der bekannten Epitope gefunden wurde. Folglich können die allergenen basophilen Aktivierungen bei den WDEIA-Patienten nicht durch das Vorhandensein bekannter WDEIA- Epitope erklärt werden.     

Van der Waals Heteroepitaxy of GaSe and InSe,Quantum Wells,and Superlattices

Bandgap engineering and quantum confinement in semiconductor heterostructures provide the means to fine-tune material response to electromagnetic fields and light in a wide range of the spectrum. Nonetheless, forming semiconductor heterostructures on lattice-mismatched substrates is a challenge for several decades, leading to restrictions for device integration and the lack of efficient devices in important wavelength bands. Here, it is shown that the van der Waals epitaxy of 2D GaSe and InSe heterostructures occur on substrates with substantially different lattice parameters, namely silicon and sapphire. The GaSe/InSe heteroepitaxy is applied in the growth of quantum wells and superlattices presenting photoluminescence and absorption related to interband transitions.     

Downstream Processing of Nucleoside‐Diphospho‐Sugars from Sucrose Synthase Reaction Mixtures at Decreased Solvent Consumption

Nucleoside‐diphospho‐sugars (NDP‐sugars) are highly demanded as specialty chemicals and as substrates for enzymatic glycosylations. Biocatalysis is efficient for their synthesis; however, downstream processing (DSP) is a bottleneck of the overall production. We describe two scalable DSP routes for recovery of NDP‐glucose (NDP‐glc) from sucrose synthase (SuSy) reaction mixtures. In both routes product precipitation with ethanol replaced size exclusion chromatography (SEC) which, due to high solvent consumption, constitutes the main limiting step of current DSP protocols. We also show that selective phosphomonoester hydrolysis by alkaline phosphatase, characterized in that it did not degrade the phosphodiester linkage in NDP‐glc, was a useful alternative to anion‐exchange chromatography (AEC) for capture and initial purification of the product. Based on comprehensive route optimization, we show uridine 5′‐diphosphate glucose (UDP‐glc) recovery at the ≥0.5 g scale in a yield of about 80% and in a purity of 86% (phosphatase route) and 95% (AEC route). Solvent savings of up to 38‐fold compared to the conventional AEC‐SEC route were achieved. There is a clear demand for both new routes, as requirements on DSP regarding purity and costs vary with the field of application. Both DSP routes seem to be applicable to other NDP‐sugars and different methods of their synthesis.