TY - THES A1 - Gerhard, Sven T1 - AlGaInP-Quantenpunkte für optoelektronische Anwendungen im sichtbaren Spektralbereich T1 - AlGaInP Quantum Dots for Optoelectronic Applications in the Visible Spectral Range N2 - Die Arbeit beschäftigt sich mit der Herstellung und Charakterisierung von AlGaInP Quantenpunkten auf GaP und GaAs-Substrat. Auf Basis dieser Quantenpunkte wurden Halbleiterlaser auf GaAs hergestellt, welche bei Raumtemperatur zwischen 660 nm und 730 nm emittierten. Die Untersuchung von Breitstreifenlasern, welche aus diesen Strukturen gefertigt wurden, legen nahe, dass man mithilfe eines höheren Aluminiumanteils in größeren Quantenpunkten bei vergleichbarer Wellenlänge Laser mit besseren Eigenschaften realisieren kann. Weiterhin wurden in dieser Arbeit Quantenpunkten auf GaP-Substrat untersucht, welche in AlGaP eingebettet wurden. Da diese Quantenpunkte in Barrieren eingebettet sind, welche eine indirekte Bandlücke besitzen, ergibt sich ein nicht-trivialer Bandverlauf innerhalb dieser Strukturen. In dieser Arbeit wurden numerische 3D-Simulationen verwendet, um den Bandverlauf zu berechnen, wobei Verspannung und interne Felder berücksichtigt wurden und auch die Grundzustandswellenfunktionen ermittelt wurden. Ein eingehender Vergleich mit dem Experiment setzt die gemessenen Emissionswellenlängen und -intensitäten mit berechneten Übergangsenergien und Überlappintegralen in Verbindung. N2 - The scope of this work is the fabrication and characterization of AlGaInP quantum dots on GaP an GaAs substrates. Based on such quantum dots, semiconductor lasers have been realized, emitting between 660 nm and 730 nm at room temperature. The examination of broad-area lasers processed on these structures suggests that active layers of larger quantum dots with higher aluminium contents lead to lasers with better performance at similar emission wavelength. Additionally, quantum dots grown on GaP substrates have been characterized, that were embedded in AlGaP barriers. Since these barriers exhibit an indirect bandgap, a non-trivial band alignment within these structures is expected. In this work, numerical 3D-simulations are employed to calculate the band alignment including strain and internal fields. Also, ground state wavefunctions of charge carriers have been determined. A thorough comparison between theory and experiment connects the measured emission wavelength and luminescence intensities with calculated transition energies and wavefunction overlaps. KW - Quantenpunkt KW - Drei-Fünf-Halbleiter KW - Optoelektronik KW - AlGaInP KW - AlGaInP KW - quantum dot KW - gallium phosphide KW - Galliumphosphid KW - Laser Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-76174 ER - TY - JOUR A1 - Irmer, Henriette A1 - Tarazona, Sonia A1 - Sasse, Christoph A1 - Olbermann, Patrick A1 - Loeffler, Jürgen A1 - Krappmann, Sven A1 - Conesa, Ana A1 - Braus, Gerhard H. T1 - RNAseq analysis of Aspergillus fumigatus in blood reveals a just wait and see resting stage behavior JF - BMC Genomics N2 - Background: Invasive aspergillosis is started after germination of Aspergillus fumigatus conidia that are inhaled by susceptible individuals. Fungal hyphae can grow in the lung through the epithelial tissue and disseminate hematogenously to invade into other organs. Low fungaemia indicates that fungal elements do not reside in the bloodstream for long. Results: We analyzed whether blood represents a hostile environment to which the physiology of A. fumigatus has to adapt. An in vitro model of A. fumigatus infection was established by incubating mycelium in blood. Our model allowed to discern the changes of the gene expression profile of A. fumigatus at various stages of the infection. The majority of described virulence factors that are connected to pulmonary infections appeared not to be activated during the blood phase. Three active processes were identified that presumably help the fungus to survive the blood environment in an advanced phase of the infection: iron homeostasis, secondary metabolism, and the formation of detoxifying enzymes. Conclusions: We propose that A. fumigatus is hardly able to propagate in blood. After an early stage of sensing the environment, virtually all uptake mechanisms and energy-consuming metabolic pathways are shut-down. The fungus appears to adapt by trans-differentiation into a resting mycelial stage. This might reflect the harsh conditions in blood where A. fumigatus cannot take up sufficient nutrients to establish self-defense mechanisms combined with significant growth. KW - Saccharomyces cerevisiae KW - cerebral aspergillosis KW - gene expression KW - Aspergillus fumigatus KW - iron homeostasis KW - invasive pulmonary aspergillosis KW - Candida albicans KW - cell wall KW - lysine biosynthesis KW - human pathogen KW - murine model KW - virulence KW - mRNA-Seq KW - transcriptome KW - human pathogenic fungi KW - secondary metabolite gene cluster KW - detoxification Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-151390 VL - 16 IS - 640 ER - TY - JOUR A1 - Gerhard-Hartmann, Elena A1 - Goergen, Helen A1 - Bröckelmann, Paul J. A1 - Mottok, Anja A1 - Steinmüller, Tabea A1 - Grund, Johanna A1 - Zamò, Alberto A1 - Ben-Neriah, Susana A1 - Sasse, Stephanie A1 - Borchmann, Sven A1 - Fuchs, Michael A1 - Borchmann, Peter A1 - Reinke, Sarah A1 - Engert, Andreas A1 - Veldman, Johanna A1 - Diepstra, Arjan A1 - Klapper, Wolfram A1 - Rosenwald, Andreas T1 - 9p24.1 alterations and programmed cell death 1 ligand 1 expression in early stage unfavourable classical Hodgkin lymphoma: an analysis from the German Hodgkin Study Group NIVAHL trial JF - British Journal of Haematology N2 - High programmed cell death 1 ligand 1 (PD-L1) protein expression and copy number alterations (CNAs) of the corresponding genomic locus 9p24.1 in Hodgkin- and Reed–Sternberg cells (HRSC) have been shown to be associated with favourable response to anti-PD-1 checkpoint inhibition in relapsed/refractory (r/r) classical Hodgkin lymphoma (cHL). In the present study, we investigated baseline 9p24.1 status as well as PD-L1 and major histocompatibility complex (MHC) class I and II protein expression in 82 biopsies from patients with early stage unfavourable cHL treated with anti-PD-1-based first-line treatment in the German Hodgkin Study Group (GHSG) NIVAHL trial (ClinicalTrials.gov Identifier: NCT03004833). All evaluated specimens showed 9p24.1 CNA in HRSC to some extent, but with high intratumoral heterogeneity and an overall smaller range of alterations than reported in advanced-stage or r/r cHL. All but two cases (97%) showed PD-L1 expression by the tumour cells in variable amounts. While MHC-I was rarely expressed in >50% of HRSC, MHC-II expression in >50% of HRSC was found more frequently. No obvious impact of 9p24.1 CNA or PD-L1 and MHC-I/II expression on early response to the highly effective anti-PD-1-based NIVAHL first-line treatment was observed. Further studies evaluating an expanded panel of potential biomarkers are needed to optimally stratify anti-PD-1 first-line cHL treatment. KW - fluorescence in situ hybridisation KW - major histocompatibility complex KW - immune checkpoint blockade KW - classical Hodgkin lymphoma KW - CD274 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-258358 VL - 196 IS - 1 ER -