Strukturelle und optische Charakterisierung von verschiedenen Ga2O3-Polymorphen

Different polymorphs of Ga2O3 were investigated by means of Raman and photoluminescence (excitation) spectroskopie. The basics of the structural properties of the known polymorphs and their differences as well as the optical properties are presented and discussed in detail. Therefore high resolution polarization or angular dependent Raman spectroscopy as well as temperature dependent and polarization dependent photoluminescence spectroscopy was perfrmed.Verschiedene Polymorphe von Ga2O3 wurden mit Hilfe von Raman und Photolumineszenz (Anregungs-) Spektroskopie untersucht. Die grundlegenden strukturellen Eigenschaften der bekannten Polmorphe und deren unterschiede, sowie deren optische Eigenschaften werden präsentiert und detailliert diskutiert. Dafür wurde hochaufgelöste polarisations- oder winkelabhängige Raman-Spektroskopie, sowie temperatur- und polarisationsabhängige Photolumineszenzspektroskopie durchgeführt

MORG1—A Negative Modulator of Renal Lipid Metabolism in Murine Diabetes

Renal fatty acid (FA) metabolism is severely altered in type 1 and 2 diabetes mellitus (T1DM and T2DM). Increasing evidence suggests that altered lipid metabolism is linked to tubulointerstitial fibrosis (TIF). Our previous work has demonstrated that mice with reduced MORG1 expression, a scaffold protein in HIF and ERK signaling, are protected against TIF in the db/db mouse model. Renal TGF-ß1 expression and EMT-like changes were reduced in mice with single-allele deficiency of MORG1. Given the well-known role of HIF and ERK signaling in metabolic regulation, here we examined whether protection was also associated with a restoration of lipid metabolism. Despite similar features of TIF in T1DM and T2DM, diabetes-associated changes in renal lipid metabolism differ between both diseases. We found that de novo synthesis of FA/cholesterol and β-oxidation were more strongly disrupted in T1DM, whereas pathological fat uptake into tubular cells mediates lipotoxicity in T2DM. Thus, diminished MORG1 expression exerts renoprotection in the diabetic nephropathy by modulating important factors of TIF and lipid dysregulation to a variable extent in T1DM and T2DM. Prospectively, targeting MORG1 appears to be a promising strategy to reduce lipid metabolic alterations in diabetic nephropathy

Electronic excitations stabilized by a degenerate electron gas in semiconductors

Excitons in semiconductors and insulators consist of fermionic subsystems, electrons and holes, whose attractive interaction facilitates bound quasiparticles with quasi-bosonic character. In the presence of a degenerate electron gas, such excitons dissociate due to free carrier screening. Despite their absence, we found pronounced emission traces in the below-band-edge region of bulk, germanium-doped GaN up to a temperature of 100 K, mimicking sharp spectral features at high free electron concentrations (3.4E19–8.9E19 cm−3). Our interpretation of the data suggests that a degenerate, three-dimensional electron gas stabilizes a novel class of quasiparticles, which we name collexons. These many-particle complexes are formed by exchange of electrons with the Fermi gas. The potential observation of collexons and their stabilization with rising doping concentration is enabled by high crystal quality due to the almost ideal substitution of host atoms with dopants.DFG, 43659573, SFB 787: Semiconductor Nanophotonics: Materials, Models, Device