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Evaluation and feasibility of diagnostic heatflow imaging in patients with palpable breast lesions: a pilot study
No full textBackground Breast cancer is the most common cancer in women, with early detection significantly improving outcomes. Heat flow imaging (HFI) is a non-invasive dynamic thermography method with prior tissue cooling. It has shown its potential as an additional diagnostic tool. The aim of the present study was to evaluate the feasibility of diagnostic HFI in patients with palpable breast lesions during outpatient visits. Methods The patients presenting with palpable breast lesions at the Erlangen University Hospital were recruited between November 2023 and April 2024. Heat flow imaging was performed in addition to sonographic and mammographic imaging in routine care. Additionally, the patients completed a pain questionnaire to evaluate the comfort of the procedure. We used a two-phase study design. During the first phase, the imaging procedure was established and standardized. In the second phase, imaging footage was compared with conventional mammography, sonography, and histological findings. Results Thirty-nine patients were recruited and 18 patients underwent final evaluation. Heat flow imaging successfully detected 7 out of 11 palpable carcinomas. Factors contributing to missed lesions and impairing image quality were inadequate cooling or improper camera positioning. The mean pain score reported during the procedure was 0.7 on a visual analog scale from 0 to 10, indicating minimal discomfort. Conclusions Heat flow imaging is a feasible imaging method that may serve as a supplementary diagnostic tool for breast cancer detection in patients with palpable breast lesions. However, it is still considered an experimental method and its use should be limited in the context of clinical trials. Further research involving larger patient groups is required to validate these preliminary findings and to optimize image acquisition protocols.Open Access funding enabled and organized by Projekt DEAL.Universitätsklinikum Erlangen (8546
Entwicklung eines stabilen, effizienten und nachhaltigen thermochemischen Energiespeichers auf Basis von Mg(OH)2, CaCl2 und Zeolithen
No full textIn thermochemical energy storage, endothermic and exothermic processes like chemical reactions or sorption processes are combined to store thermal energy. Mostly one compound is a solid and the other one is a vapor or a gas.
This study focuses on thermochemical energy storage for temperatures above 150 °C. The target is to develop a material system with a high stability and a low temperature gab between the charging and the discharging step. Furthermore, a system with a low environmental impact should be identified with the help of the LCA methodology. Additionally, the influence of the life-time of the marterial on the ecological footprint is evaluated. In this study, three different material systems were evaluated and for each material system strategies were tested to enhance the stability and to reduce the temperature gab between the charging and the discharging step.
The system MgO/Mg(OH)2 is prone to sintering and agglomeration if pure powder is used. For this reason, the loading of Mg(OH)2 onto microporous activated carbon pellets is tested. A homogeneous distribution of magnesium hydroxide over the cross-section of the pellets was not reached. However, the prepared composite showed a good stability over several cycles. A maximum temperature rise ΔT of 48 °C was observed in the test-rig during the discharging of the storage. Furthermore, LiCl was added to Mg(OH)2 in order to reduce the charging temperature of the storage system. The presence of lithium chloride on the Mg(OH)2/activated carbon composite triggers a reduction of the dehydration temperature by 10 K and a 30 % higher conversion in the discharging step. This results in an enhanced exergetic efficiency of the composite material.
The material system CaCl2/H2O also appeared to be a promising candidate for heat storage above 150 °C. Similar to MgO/Mg(OH)2, also pure CaCl2 powder showed agglomerartion and sintering after few hydration / dehydration cycles. Therefore, in this study, CaCl2 was loaded onto porous alumina and zeolites in order to achieve long-term stability. The composites with alumina showed a stable performance over 20 cycles. Throughout the heat release step, a maximum temperature rise ΔT of 40 °C was detected in the test rig. The problems in using pure CaCl2 (agglomeration, sintering) were solved. However, it was found that the sorption capacity and the temperature increase of pure zeolite Y during the discharging of the storage is higher than for the CaCl2-loaded composite.
Therefore, unloaded zeolite pellets were studied in detail. For tailoring the properties of the zeolites in this temperature range, ion-exchange from Na+-ions to Ca2+- and Mg2+-ions is used. Compared to the sodium and calcium form, magnesium-exchanged zeolite Y showed a higher sorption capacity and a stronger heat release. A maximum ΔT of 100 °C during the discharging of the zeolite storage was detected. Zeolite Y showed a good stability over 60 cycles. Furthermore, with zeolite Y, the steps of heat storage and heat release can be realized on the same temperature level, which is favorable for achieving high exergetic efficiencies. Comparing the three materials systems, zeolite Y is the most promising material for heat storage applications above 150 °C due to its good stability, the absence of a temperature hysteresis and the high ΔT reached in the experiments.
The environmental impacts of thermochemical heat storage were studied in comparison with other heating options. In a first scenario, the use of magnesium oxide and zeolite in thermal energy storage was compared to commercially available latent and sensible storage systems. Due to their higher storage density, the thermochemical storage materials zeolite and magnesium hydroxide show the lowest ecological impacts.
Moreover, the heating with a thermochemical energy storage system based on zeolites is compared to heating with electricity from renewable sources, e.g. wind and solar power. The results show that a thermochemical storage system with zeolites must be used for up to 1000 cycles to guarantee lower environmental impacts than electrical heating with renewables. Therefore, these thermochemical storage systems are not suited for seasonal storage applications
Optimization and validation of the international metabolic prognostic index for CD19 CAR-T in large B-cell lymphoma
No full textWhile CD19-directed CAR T-cell therapy represents a transformative immunotherapy for relapsed/refractory large B-cell lymphoma (r/r LBCL), more than 50% of patients ultimately progress or relapse. Recently, the International Metabolic Prognostic Index (IMPI) – incorporating age, stage, and metabolic tumor volume (MTV) – was shown to improve prognostication for LBCL frontline treatment. Here, we examine its utility to predict toxicity and survival in CAR-T recipients. This multicenter observational study spanning six international sites included 504 patients with available 18 FDG-PET/CT imaging at last response assessment prior to lymphodepletion. Optimal CAR-adapted MTV thresholds were identified in a development cohort ( n = 256) and incorporated into a CAR-T-specific IMPI (“CAR-IMPI”). The prognostic performance of CAR-IMPI was validated in an independent cohort ( n = 248). CAR-IMPI risk categories, defined by the median (1.35) and terciles (1.07, 1.58), demonstrated significant discrimination for progression-free survival (PFS; p < 0.0001) and overall survival (OS; p < 0.0001) in both cohorts. Multivariate Cox regression confirmed CAR-IMPI as an independent predictor of survival, accounting for pre-lymphodepletion LDH and CRP, performance status, treatment center, and CAR-T product. Patients in the CAR-IMPI high-risk category experienced increased severity of CRS and ICANS, and higher rates of intensive care unit (ICU) admissions. In an exploratory analysis, combining CAR-IMPI with established indices of high-risk systemic inflammation (CAR-HEMATOTOX, InflaMix) further enhanced survival stratification. The CAR-IMPI may provide a potent and validated PET-based tool for risk stratification of clinical outcomes in patients with r/r LBCL receiving CD19 CAR-T therapy. Our data highlight the utility of combining clinical and radiological modalities, with implications for patient selection and the anticipated level-of-care for toxicity management.Else Kröner Forschungskolleg (EKFK) Bavarian Cancer Research Center (BZKF; BZKF-#TLG-22) Bruno and Helene Jöster Foundation MSKCC Core grant (P30 CA008748)Förderung für Forschung und Lehre (FöFoLe) LMU Munich (#1147) Bavarian Cancer Research Center (BZKF)MSKCC Core grant (P30 CA008748) NIH-NCI K-award (K08CA282987) Comedy vs. Cance
Tuning Electrocatalytic Energy Release in Norbornadiene Based Molecular Solar Thermal Systems Through Substituent Effects
No full textMolecular solar thermal (MOST) systems, such as the norbornadiene/quadricyclane (NBD/QC) pair, combine solar energy conversion, storage, and release in a simple one‐molecule process. The energy‐releasing reaction QC to NBD can be controlled electrochemically. In this study, we used in‐situ photoelectrochemical infrared spectroscopy (PEC‐IRRAS) together with density functional theory (DFT) calculations to investigate how electron donating (EDG) and electron withdrawing (EWG) groups in the push‐pull system of the MOST pair affect the electrocatalytic properties of the electrochemically triggered back‐conversion. Specifically, we investigated cyano, tosyl, and methyl ester groups as EWGs, and methoxy, dimethylamine, thioether, and diphenylamine groups located in the para ‐position of a phenyl group as EDGs. We characterized the onset potential, electrochemical stability window, and selectivity. We found that these properties strongly depend on the strength of electron donation of the EDG, as it exclusively locates the highest occupied molecular orbital (HOMO) and raises its energy level. We obtained the highest selectivity for compounds with p ‐methoxyphenyl functionality.We investigated how push–pull substituents influence the electrochemically driven energy release in norbornadiene‐based MOST systems. Electron‐donating groups proved to be decisive, with p‐methoxyphenyl derivatives achieving up to 99% selectivity. These insights offer valuable design guidelines for future MOST systems. imageEuropean Research Council 10.13039/501100000781Horizon 2020 10.13039/501100007601Deutsche Forschungsgemeinschaft 10.13039/50110000165
Approximate Message Passing in der Compressive Sensing Radarsignalverarbeitung
No full textRadar sensors transmit radio waves to gather information about a target scene by
processing the returning signals. The quality of the radar system’s reconstruction
depends on various factors, such as transmit power, available bandwidth, length of the
observation interval, aperture width of the antenna, or number of antenna elements
employed. Beyond these factors determined by hardware and system limitations,
reconstruction quality can be significantly enhanced by using sophisticated signal
processing methods.
Prominent examples of signal processing methods used to improve radar signal reconstructions
are the so-called Compressive Sensing (CS) algorithms. CS allows for
the reconstruction of signals from an undersampled set of linear measurements. This
is made possible by recovering the signal not only from the measurements but also
from known structures in the signals of interest. CS thereby can increase a sensing
system’s performance or reduce the system’s sensor requirements while preserving a
high reconstruction quality.
However, recovering a signal from a compressed set of measurements is a non-trivial
problem and typically comes at the price of significant computational cost. Various CS
reconstruction schemes exist in the literature. While classical reconstruction methods
are mostly based on convex optimization, more modern approaches are based on
message-passing and arise from modelling the reconstruction problem as a factor
graph. This family of reconstruction algorithms is known as Approximate Message
Passing (AMP). Although CS methods have been widely applied in radar systems,
AMP reconstruction schemes have rarely been used. The central goal of this thesis is
therefore to investigate these types of algorithms in radar signal processing. To this
end, we develop a series of AMP-based reconstruction algorithms for various radar
scenarios and evaluate their performance.
We start by introducing an AMP-based super-resolution algorithm that can cope with
different radar scenarios. It is based on the so-called Vector Approximate Message
Passing (VAMP) algorithm and achieves a reconstruction accuracy that far exceeds the natural resolution of the respective radar system. By comparing the VAMP-based
super-resolution algorithm with a 1-minimization-based approach from literature, we
demonstrate the advantages of the proposed method, particularly in terms of the
number of targets it can reliably handle.
We then develop a related VAMP-based reconstruction method for a 3D near-field
MIMO radar imaging scenario. This method is based on an innovative signal transform,
which projects a 3D compact object into a 2D plane. The algorithm can achieve high
lateral resolution and very high accuracy in depth while simultaneously reducing the
required measurement time. This is of particular importance for moving objects, which
also require a high temporal resolution.
In another scenario, we investigate the reconstruction of moving point-like targets
in the array far-field of a co-located MIMO radar. More specifically, we recover a
sparse target scene of constant-velocity objects from multiple snapshots. The strong
correlation between snapshots invites a joint reconstruction, which leads to a significant
reduction in the number of required antenna elements. In this setting, we develop an
AMP and a more advanced VAMP-based reconstruction algorithm and demonstrate
their performance in a series of numerical experiments.
Finally, in the context of MIMO radar, we also address the question of antenna
placement, which is of great importance for AMP algorithms. In co-located MIMO
radar, the exact placements of the antenna elements largely define the resulting
measurement matrix. Proper design of the measurement matrix is critical for any CS
reconstruction scheme but is of particular importance for AMP-based algorithms. We
therefore introduce a convex relaxation-based optimization method, which alternatively
optimizes the radar’s transmit and receive array, with respect to the coherence of the
resulting measurement matrix. In a numerical investigation, we demonstrate that the
developed placement scheme can find matrices with lower coherence, while using less
computation time, compared to benchmark algorithms from the literature.Radarsensoren senden Radiowellen aus, um Informationen über eine Zielszene zu gewinnen,
indem sie die rückgestreuten Signale verarbeiten. Die Qualität der Rekonstruktion
eines Radarsystems wird dabei von einer Vielzahl von Faktoren bestimmt, wie etwa der
Sendeleistung, der nutzbaren Bandbreite, der Dauer des Beobachtungsintervalls, der
Aperturweite der Antenne oder der Anzahl der eingesetzten Antennenelemente. Über
diese durch Hardware- und Systembeschränkungen bestimmten Faktoren hinaus kann
die Rekonstruktionsqualität durch den Einsatz moderner Signalverarbeitungsmethoden
erheblich gesteigert werden.
Ein prominentes Beispiel für Signalverarbeitungsmethoden zur Verbesserung von
Radarsignalrekonstruktionen sind sogenannte Compressive Sensing (CS) Algorithmen.
CS ermöglicht die Rekonstruktion von Signalen aus einer unterabgetasteten
Menge linearer Messungen. Dies wird möglich, indem das Signal nicht nur aus den
Messungen selbst, sondern auch aus strukturellen Eigenschaften der betrachteten
Signale wiederhergestellt wird. Hierdurch ist CS in der Lage, die Leistungsfähigkeit
von Sensorsystemen zu erhöhen oder die Anforderungen an die Sensorhardware zu
reduzieren, während eine hohe Rekonstruktionsqualität erhalten bleibt.
Die Rekonstruktion eines Signals aus einem komprimierten Satz von Messungen ist
jedoch ein anspruchsvolles Problem, das in der Regel mit erheblichem Rechenaufwand
verbunden ist. In der Literatur existieren verschiedene Rekonstruktionsverfahren für
CS. Während klassische Rekonstruktionsmethoden überwiegend auf konvexer Optimierung
beruhen, basieren moderne Ansätze auf Message Passing und resultieren
aus der Modellierung des Rekonstruktionsproblems als Faktorgraph. Diese Familie
von Rekonstruktionsalgorithmen wird unter dem Begriff Approximate Message Passing
(AMP) zusammengefasst. Obwohl CS-Methoden in der Radartechnik bereits
vielfach angewendet wurden, ist der Einsatz von AMP-Rekonstruktionsverfahren bislang
nur selten untersucht worden. Ziel dieser Arbeit ist es daher, das Potenzial dieser
Algorithmen in der Radarsignalverarbeitung zu erforschen. Zu diesem Zweck entwickeln
wir eine Reihe von AMP-basierten Rekonstruktionsalgorithmen für verschiedene
Radarszenarien und evaluieren deren Leistungsfähigkeit.
Zunächst entwickeln wir einen AMP-basierten Super-Resolution Algorithmus, der auf
dem so genannten Vector Approximate Message Passing (VAMP) Algorithmus beruht
und in unterschiedlichen Radarszenarien eingesetzt werden kann. Der Algorithmus
erreicht eine Rekonstruktionsgenauigkeit, die die natürliche Auflösung des jeweiligen
Radarsystems deutlich übertrifft. Im Vergleich mit einem auf 1-Minimisierung basierenden
Ansatz aus der Literatur, demonstrieren wir diverse Vorteile der vorgeschlagenen
Methode, insbesondere hinsichtlich der maximalen Anzahl von Zielen, die zuverlässig
rekonstruiert werden kann.
Darauf aufbauend entwickeln wir eine verwandte VAMP-basierte Rekonstruktionsmethode
für ein 3D-Nahfeld-MIMO-Radarszenario. Diese Methode beruht auf einer
innovativen Signaltransformation, die ein kompaktes 3D-Objekt in eine 2D-Ebene
projiziert. Der vorgestellte Algorithmus ermöglicht eine hohe laterale Auflösung und
eine sehr hohe Genauigkeit in der Tiefe, während gleichzeitig die erforderliche Messzeit
signifikant reduziert wird. Dies ist insbesondere bei bewegten Objekten von großer
Bedeutung, die eine hohe zeitliche Auflösung erfordern.
In einem weiteren Szenario untersuchen wir die Rekonstruktion von bewegten punktförmigen
Zielen im Antennen-Fernfeld eines kolokalisierten MIMO-Radars. Konkret
betrachten wir eine spärliche Zielszene aus Objekten mit konstanter Geschwindigkeit,
die anhand mehrerer zeitlich aufeinanderfolgender Radaraufnahmen rekonstruiert wird.
Die starke Korrelation zwischen diesen Aufnahmen legt eine gemeinsame Rekonstruktion
nahe, wodurch sich die Anzahl der benötigten Antennenelemente signifikant
reduzieren lässt. Für dieses Szenario entwickeln wir sowohl einen AMP- als auch einen
weiterentwickelten VAMP-basierten Rekonstruktionsalgorithmus und demonstrieren
deren Leistungsfähigkeit in numerischen Simulationen.
Abschließend widmen wir uns im Kontext von MIMO-Radaren der Frage der Antennenplatzierung,
die für AMP-basierte Rekonstruktionsverfahren von zentraler Bedeutung
ist. In kolokalisierten MIMO-Radar Szenarien wird die resultierende Messmatrix maßgeblich
durch die exakte Positionierung der Sende- und Empfangselemente bestimmt.
Eine geeignete Gestaltung dieser Messmatrix ist für jedes CS-Verfahren essenziell, für
AMP-basierte Algorithmen jedoch von besonderer Bedeutung. Hierzu stellen wir ein
Optimierungsverfahren vor, das auf konvexer Relaxation basiert und alternierend das
Sende- und Empfangsarray im Hinblick auf die Kohärenz der resultierenden Messmatrix
optimiert. Anhand numerischer Experimente zeigen wir, dass das vorgeschlagene
Platzierungsschema Messmatrizen mit geringerer Kohärenz identifizieren kann und
dabei weniger Rechenzeit benötigt als Referenzverfahren aus der Literatur
Optische Untersuchung der Gasphasensynthese metalloxidischer und kohlenstoffhaltiger Nanopartikel
No full textDie Sprühflammensynthese (SFS) ist eine vielversprechende Methode für die Herstellung metalloxidischer Nanopartikel (MONP). Bei diesem Verfahren wird eine Lösung aus einem Lösungsmittel und einer Vorläufersubstanz in eine Flamme eingesprüht und durch einen Gasstrom in kleine Tropfen zerstäubt. Durch verschiedene Prozesse kommt es dann zur Partikelbildung, die aufgrund ihrer Komplexität jedoch nicht im Detail verstanden sind. Um diese Wissenslücken in einem systematischen und ganzheitlichen Ansatz zu schließen, wurden im Rahmen des Schwerpunktprogrammes (SPP) 1980: „Nanopartikelsynthese in Sprayflammen - SpraySyn: Messung, Simulation, Prozesse“ der Deutschen Forschungsgemeinschaft (DFG) die standardisierten Sprühflammenbrenner SpraySyn 1.0 und SpraySyn 2.0 entwickelt, um Experimente sowie Simulationen an ihnen durchzuführen. Der SpraySyn 2.0-Brenner stellt eine Weiterentwicklung der Version 1.0 dar, da diese eine stark instabile Flamme aufweist und inhomogene Partikelgrößen produziert. Diese Arbeit beschäftigt sich schwerpunktmäßig mit der Untersuchung verschiedener Aspekte der Entstehung von Eisenoxid- (EONP) und Titandioxidnanopartikeln (TDNP) im SpraySyn 2.0-Brenner unter Nutzung optischer Messtechniken. Diese erlauben eine berührungslose Untersuchung der Vorgänge im Brenner und sind daher ein essentielles Werkzeug, um die Partikelbildung in der SFS besser zu verstehen.
Um die Entwicklung der Größe der untersuchten MONP entlang der Höhe über der Brenneroberfläche (HüB) der SFS zu messen, wurde im Rahmen dieser Arbeit für beide Partikelarten die Weitwinkel-Lichtstreuung (engl.: wide-angle light scattering, WALS) genutzt. Ergänzend kam für die EONP zudem erstmals in einer SFS die laserinduzierte Inkandeszenz (engl.: laser-induced incandescence, LII) zum Einsatz. LII bietet den Vorteil, dass auch in niedrigen HüB das Partikelwachstum verfolgt werden kann, trotz der dort noch vorliegenden Tropfen. Deren Streusignale sorgen bei streulichtbasierten Messtechniken wie WALS für eine Überlagerung mit den Streusignalen der Partikel, wodurch Aussagen über Partikelgrößen kaum möglich sind.
Zur Auswertung von Partikelgrößen aus LII-Messdaten werden allerdings Modellparameter benötigt, deren Datenlage für die EONP jedoch sehr eingeschränkt ist. Aus diesem Grund wurde im Rahmen dieser Arbeit vor der Untersuchung der Partikelsynthese im SpraySyn 2.0-Brenner eine neue Methode zur in situ Bestimmung von LII-Modellparametern entwickelt. Diese beruht auf der zeitlich aufgelösten Messung und Auswertung breiter Spektren des LII-Signals und wurde umfassend in situ an gut charakterisierten Rußpartikeln in der Flamme eines Standardbrenners getestet.
Das Verfahren wurde anschließend genutzt, um den in dieser Arbeit erstmals experimentell ermittelten thermischen Akkommodationskoeffizienten (TAK) von EONP, einen wichtigen LII-Modellparameter, innerhalb der SFS zu validieren. Nach erfolgreicher Validierung wurde die LII dann zur Untersuchung der Größenentwicklung der EONP von 10 mm bis 50 mm HüB im SpraySyn 2.0-Brenner eingesetzt. Aus diesen Messungen wurde ein über alle HüB hinweg relativ konstanter effektiver Partikeldurchmesser von etwa 300 nm ermittelt. Aufgrund des hohen Wertes in sehr niedrigen HüB ist die Partikelbildung vermutlich auf eine sehr früh im Brenner einsetzende Tropfen-zu-Partikel-Syntheseroute zurückzuführen.
In einem weiteren Schritt wurde LII zudem eingesetzt, um erstmals in situ in einer Eisenoxid-SFS die Lage der Partikelbildungszone zu lokalisieren. Diese Messungen zeigen einen nahezu linearen Anstieg der produzierten relativen Partikelmasse bis ca. 30 mm HüB, gefolgt von einem Bereich konstanter Masse bis ca. 50 mm HüB.
WALS als komplementäre Größenmesstechnik zu LII wurde aufgrund der Tropfen im SpraySyn 2.0-Brenner während der Herstellung von EONP und TDNP erst ab ca. 30 mm HüB eingesetzt. Für beide Materialien zeigen die WALS-Messungen ein Anwachsen der Partikelgröße bis ca. 80 mm HüB. Dieser vermeintliche Widerspruch zu den Ergebnissen der LII-Messungen an den EONP wird in dieser Arbeit in einem simulationsbasierten Ansatz auf Unterschiede in der Sensitivität beider Messtechniken zurückgeführt.
Neben den Partikeln wurde im Rahmen dieser Arbeit auch die Entwicklung der Tropfengröße entlang der HüB mit WALS untersucht, da diese Einfluss auf den Partikelentstehungsprozess hat. Die Auswertung dieser Messungen zeigen deutlich kleinere Tropfen als im SpraySyn 1.0-Brenner, was letztlich insgesamt zu einem schnelleren Verdampfen und damit dem Beginn der Partikelproduktion in niedrigeren HüB führt.
Auch die Fluktuationen der Flamme des Brenners wurden im Rahmen dieser Arbeit untersucht, da ihr Einfluss auf die Partikelbildung bislang ungeklärt war. Daher wurde erstmals eine gekoppelte berührungslose Untersuchung der Fluktuationen und der Partikelgröße durchgeführt. Hierbei wurde kein Zusammenhang zwischen beiden festgestellt.Spray flame synthesis (SFS) is a promising method for the production of metal-oxide nanoparticles (MONP). In this process, a solution of a solvent and a precursor is sprayed into a flame and is atomised into small droplets by a gas stream. Various processes then lead to particle formation, which are, however, not understood in detail due to their complexity.
In order to close these gaps in knowledge in a systematic and holistic approach, the standardised spray flame burners SpraySyn 1.0 and SpraySyn 2.0 were developed as part of the Priority Programme 1980: “Nanoparticle Synthesis in Spray Flames - SpraySyn: Measurement, Simulation, Processes” of the German Research Foundation (DFG) in order to carry out experiments and simulations on them. The SpraySyn 2.0-burner represents a modification of the 1.0 version, as the latter shows a highly unstable flame and produces inhomogeneous particle sizes. This work focuses mainly on the investigation of various aspects of the formation of iron oxide (IONP) and titanium dioxide nanoparticles (TDNP) in the SpraySyn 2.0-burner using optical measurement techniques. These allow a non-invasive investigation of the processes in the burner and are therefore an essential tool to better understand particle formation in the SFS.
To measure the development of the particle sizes of the investigated MONP along the height above the burner surface (HAB) of the SFS, wide-angle light scattering (WALS) was used for both particle types in this work. Additionally, laser-induced incandescence (LII) was used for the first time in an iron oxide SFS-process to determine particle sizes. LII offers the advantage that particle growth can also be tracked at low HAB, despite the droplets still being present there. In light scattering-based measurement techniques such as WALS, the scattering signals of the droplets are superimposed on the scattering signals of the particles, making it almost impossible to make statements about particle sizes.
However, in order to analyse particle sizes from LII measurement data, model parameters are required whose availability for the IONP is very limited. For this reason, a new method for the in situ determination of LII model parameters was developed as part of this work prior to the investigation of particle synthesis in the SpraySyn 2.0-burner. This method is based on the time-resolved measurement and evaluation of broad spectra of the LII-signal and has been extensively tested in situ on well-characterised soot particles in the flame of a standard burner.
The method was then used to validate an important LII model parameter, the thermal accommodation coefficient (TAC) of IONP, which was determined experimentally for the first time in this work in prior investigations outside the burner. After successful validation of the TAK within the SFS, LII was then used to investigate the size development of the IONP from 10 mm to 50 mm HAB in the SpraySyn 2.0-burner. From these measurements, a relatively constant effective particle diameter of around 300 nm was determined throughout all HAB. Due to this high value at very low HAB, the particle formation is probably due to a droplet-to-particle synthesis route that starts in very low HAB in the burner.
In a subsequent step, LII was also used to localise the region of the particle formation zone for the first time in situ in an iron oxide SFS-process. These measurements show an almost linear increase in the produced relative particle mass up to approx. 30 mm HAB, followed by a range of constant mass up to approx. 50 mm HAB.
WALS as a complementary particle sizing technique to LII was used during production of IONP and TDNP only from approx. 30 mm HAB due to the droplets in the SpraySyn 2.0-burner. For both materials, the WALS measurements show an increase in particle size up to approx. 80 mm HAB. This apparent discrepancy with the results of the LII measurements on the IONP is attributed in this work to differences in the sensitivity of the two measurement techniques using a simulation-based approach.
In addition to the particles, the development of the droplets in terms of their size along the HAB was also investigated with WALS as this has an influence on the particle formation process. The evaluation of these measurements shows significantly smaller droplets than in the SpraySyn 1.0-burner, which ultimately leads to faster evaporation and thus the start of particle production in lower HAB.
The fluctuations of the burner were also investigated as part of this work, as their influence on particle formation was previously unclear. Therefore, a coupled non-invasive investigation of the fluctuations and the particle size was carried out for the first time within this work. No correlation between the two was found
The microbial metabolite desaminotyrosine protects against graft-versus-host disease via mTORC1 and STING-dependent intestinal regeneration
No full textChanges in the intestinal microbiome and microbiota-derived metabolites predict clinical outcomes after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Here, we report that desaminotyrosine (DAT), a product of bacterial flavonoid metabolism, correlates with improved overall survival and reduced relapse rates in patients receiving allo-HSCT. In preclinical mouse models, treatment with synthetic DAT prevents graft-versus-host disease by protecting the intestinal barrier and promoting intestinal regeneration and contributes to graft-vs.-leukemia responses. DAT´s beneficial effects on intestinal regeneration remain effective despite broad-spectrum antibiotics-induced dysbiosis, also when administered by fecal microbiota transfer with flavonoid-degrading F. plautii . Mechanistically, DAT promotes mTORC1-dependent activation and proliferation of intestinal stem cells, with concomitant engagement of the innate immune receptor STING required to mitigate metabolic stress and maintain an undifferentiated stem cell state independently of type-I interferon responses. Additionally, DAT can skew T cells towards an effector phenotype to modulate graft-versus-leukemia responses. Our data uncover DAT’s dual, tissue- and immune-modulating properties and underscore its potential in precision microbiome-based therapies to improve tissue regeneration and minimize immune-mediated side effects.The success of allogeneic hematopoietic stem cell transplantation for the treatment of haematological cancers is limited by the morbidity and mortality associated with graft-versus-host disease (GVHD). Here the authors show that the microbial metabolite desaminotyrosine contributes to graft-versus-leukemia responses while protecting against GVHD and promoting mTORC1 and STING-dependent intestinal regeneration.Deutsche Forschungsgemeinschaft (German Research Foundation)https://doi.org/10.13039/501100001659The Else- Kröner-Fresenius-Stiftung Deutsches Konsortium fuür Translationale Krebsforschun
Compatibility of family and clinical–scientific career for German gynecologists in different workplaces: a sub-analysis of the systematic trinational FARBEN survey
No full textIntroduction The trinational survey project conducted by the young forums of the German, Austrian, and Swiss societies for gynecology and obstetrics aims to evaluate the preferences of prospective and practicing gynecologists regarding various working time models, training systems, career pathways, and the reconciliation of professional and family life. Materials and methods Between October 2023 and May 2024, 1364 participants completed the FARBEN survey. The questionnaire comprised 62 items addressing aspects such as general workplace conditions, working time models, training priorities, team structures, and professional aspirations. Participation was voluntary and anonymous. The present analysis constitutes a national sub-analysis focusing on the preferences of German respondents, stratified by their current workplace setting (university hospitals, non-university hospitals, or outpatient care facilities). Results Among the 1008 German respondents, 26.3% were employed in university hospitals, 55.4% in non-university hospitals, and 10.8% in outpatient care. Respondents working in university hospitals were significantly more likely to pursue an academic career (68.0% held a doctoral degree, and 7.5% held a habilitation—the highest academic qualification in German-speaking countries—or a professorship; 38.5% aspired to a habilitation, compared to 6.6% in non-university hospitals). Female respondents employed in university hospitals tended to have children at a later stage and returned to work earlier following parental leave. Institutional childcare was reported to be more accessible and flexible at university hospitals (20.4%) compared to non-university hospitals (9.6%) and outpatient care (8.4%). Furthermore, 34.1% of university hospital respondents indicated that their department head was female, in contrast to 19.2% in non-university hospitals ( p < 0.001). Conclusions Work–life balance and the compatibility of family life with a medical career are essential for most gynecologists in training, irrespective of their workplace setting. Respondents employed in academic institutions were more inclined to pursue scientific careers and reported greater flexibility and better childcare support. In light of the growing shortage of medical professionals, employment policies should prioritize these aspects. Initiatives such as the guideline “Safe Surgery During Pregnancy” can support the alignment of clinical training with family planning and help prevent career disadvantages related to parenthood.Open Access funding enabled and organized by Projekt DEAL.Universitätsklinikum Erlangen (8546
Deciphering brain organoid heterogeneity by identifying key quality determinants
No full textBrain organoids derived from human pluripotent stem cells (hPSCs) hold immense potential for modeling neurodevelopmental processes and disorders. However, their experimental variability and undefined organoid selection criteria for analysis hinder reproducibility. As part of the Bavarian ForInter consortium, we generated 72 brain organoids from distinct hPSC lines. We conducted a comprehensive analysis of their morphological and cellular characteristics at an early stage of their development. In our assessment, the Feret diameter emerged as a reliable, single parameter that characterizes brain organoid quality. Transcriptomic analysis of our organoid identified the abundance of unintended mesodermal differentiation as a major confounder of unguided brain organoid differentiation, correlating with Feret diameter. High-quality organoids consistently displayed a lower presence of mesenchymal cells. These findings provide a framework for enhancing brain organoid standardization and reproducibility, underscoring the need for morphological quality controls and considering the influence of mesenchymal cells on organoid-based modeling.Analyzing Feret diameter is a straightforward way to assess the quality of unguided brain organoids. Low-quality brain organoids show a high Feret diameter, accompanied by a higher proportion of unintended mesenchymal cells.Else Kröner-Fresenius-Stiftung (Else Kroner-Fresenius Foundation)https://doi.org/10.13039/501100003042Friedrich Alexander University of Erlangen Nuremberg | Medizinische Fakultät, Friedrich-Alexander-Universität Erlangen-Nürnberg (Faculty of Medicine, Friedrich Alexander University of Erlangen Nuremberg)https://doi.org/10.13039/501100009508Bundesministerium für Bildung und Forschung (Federal Ministry of Education and Research)https://doi.org/10.13039/501100002347Deutsche Forschungsgemeinschaft (German Research Foundation)https://doi.org/10.13039/50110000165
2D:4D-Fingerlängenverhältnis und akademischer Erfolg, gemessen am Erreichen des akademischen Grads ,,Habilitation‘‘
No full textDas 2D:4D Fingerlängenverhältnis beschreibt das Fingerlängenverhältnis des Zeigefingers-
(2D) zum Ringfinger (4D) und dient seit einigen Jahren als Biomarker für die pränatale und
frühkindliche Androgenkonzentration.
Das Fingerlängenwachstum und -verhältnis soll durch die pränatalen und frühkindlichen
Androgene reguliert werden. Weiterhin wird vermutet, dass die pränatale Androgenexposition
organisierende Effekte auf die Gehirnentwicklung und somit Auswirkungen auf das spätere
Verhalten hat. So konnten Zusammenhänge zwischen dem 2D:4D-Fingerlängenverhältnis und
bestimmten Persönlichkeits- und Verhaltensmerkmalen nachgewiesen werden.
Basierend auf diesen Ergebnissen soll in der vorliegenden Studie ein möglicher Zusammenhang
zwischen dem 2D:4D Fingerlängenverhältnis und dem akademischen Erfolg im Bereich der
Medizin dargestellt werden. Es stellt sich die Frage, ob ein hohes (niedrige pränatale
Androgenspiegel) oder ein niedriges (hohe pränatale Androgenspiegel) 2D:4D
Fingerlängenverhältnis verbunden mit gewissen Eigenschaften vorteilhaft für die akademische
Laufbahn in der Medizin ist. Weiterhin werden der Unterschied zwischen dem akademischen
Erfolg von Männern und Frauen und potenzielle Einflussfaktoren diskutiert. Ergebnisse dieser
Studie wurden bereits in der zugehörigen Publikation ,,Digit ratio (2D:4D) and academic
success as measured by achievement in the academic degree "Habilitation"‘‘ von Tektas et al.
2019 veröffentlicht (Tektas et al. 2019)