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We present scalable large area terahertz (THz) emitters based on a nanoscale multilayer InGaAs/InAlAs heterostructure and a microstructured electrode pattern. The emitters are designed for pump lasers working at the telecommunication wavelength of 1.55µm. Electric THz fields of more than 2.5 V/cm are reached with moderate pump powers of 80 mW, the corresponding spectrum extends up to 3 THz. The saturation characteristics have been investigated for different pump laser spot sizes. For small pump powers of less than 50 mW the emitted THz field is nearly independent of the spot size, for higher pump powers and small spot sizes a clear saturation of the generated THz pulse can be observed. Hence the usage of scalable emitters is especially promising for high power fibre laser systems. The spectral content of the generated radiation is nearly independent of the parameters spot size, pump power, and bias voltage, which allows for stable operation in spectroscopic applications.

The influence of localization and disorder in (GaIn)As/(AlIn)As heterostructures with spatially separated photoconductive and recombination regions designed as a material for THz antennas for telecom applications at 1.55µm is investigated by photoluminescence spectroscopy. The emission is studied as a function of lattice temperature for a series of samples with different growth temperatures. Strain-induced disorder is identified as the main contribution to carrier localization. In addition, inhomogeneous broadening as well as PL intensity is strongly influenced by the impurity density in the barrier material. The optimal configuration as THz antenna material is achieved at a growth temperature of 375 °C.

We present a scalable large-area terahertz (THz) emitter designed for excitation with 1.55 µm pump radiation. It is based on an InGaAs heterostructure combined with a microstructured electrode pattern. Electric fields of more than 2.5 V/cm in the THz focus are reached, the spectrum of the pulses extends up to 3 THz.

We report on scalable large-area terahertz emitters and detectors based on In0.53Ga0.47As/In0.52Al0.48As heterostructures for excitation with 1.55 mm radiation. Different geometries involving three different electrode gap sizes are compared with respect to terahertz (THz) emission, bias field distribution, and Joule heating. The field distribution becomes more favorable for THz emission as gap size increases, while Joule heating exhibits the opposite dependence. Devices with three different gap sizes, namely 3 mm, 5 mm, and 7.5 mm, have been investigated experimentally, the emitter with a gap size of 7.5 mm showed the best performance. The scalable devices are furthermore employed as detectors. The scalable electrode geometry enables spatially integrated detection, which is attractive for specific applications, e.g., where an unfocused THz beam has to be used.

Wnt/beta-catenin signalling controls adult heart remodelling in part via regulation of cardiac progenitor cell (CPC) differentiation. An enhanced understanding of mechanisms controlling CPC biology might facilitate the development of new therapeutic strategies in heart failure. We identified and characterized a novel cardiac interaction between Krueppel-like factor 15 and components of the Wnt/beta-catenin pathway leading to inhibition of transcription. In vitro mutation, reporter assays and co-localization analyses revealed that KLF15 requires both the C-terminus, necessary for nuclear localization, and a minimal N-terminal regulatory region to inhibit transcription. In line with this, functional Klf15 knock-out mice exhibited cardiac beta-catenin transcriptional activation along with functional cardiac deterioration in normal homeostasis and upon hypertrophy. We further provide in vivo and in vitro evidences for preferential endothelial lineage differentiation of CPCs upon KLF15 deletion. Via inhibition of beta-catenin transcription, KLF15 controls CPC homeostasis in the adult heart similar to embryonic cardiogenesis. This knowledge may provide a tool for reactivation of this apparently dormant CPC population in the adult heart and thus be an attractive approach to enhance endogenous cardiac repair.

Udgivelsesdato: July

Accumulating evidence indicates that Visinin-like protein-1 (VILIP-1), a member of the family of neuronal calcium sensor proteins (NCS), modulates a variety of processes in extra-neuronal tissues. In this study, we describe VILIP-1 expression in the human heart, rat cardiomyocytes, and H9c2 cells, and demonstrate that VILIP-1 regulates the cell surface localization of natriuretic peptide receptor B (NPR-B). In preparations from failing hearts, we observed VILIP-1 downregulation and reduced NPR-B signalling. In conclusion, VILIP-1 deficiency may be responsible for the reduced efficiency of the natriuretic peptide system in cardiac hypertrophy and heart failure and may therefore serve as pharmacological target.

In this pilot study, we report for the first time on persistent organic pollutants (POPs) measured in polar bear (Ursus maritimus) hair, in an effort to validate hair as a non-invasive matrix representative of concentrations and profiles in internal organs and blood plasma. Among the findings, only five PCB congeners (CB 99, 138, 153, 170 and 180), one PBDE congener (BDE 47), oxychlordane, trans-nonachlor and β-HCH could be quantified in hair samples, which was likely a function of low sample weights (30-140 mg). Statistical analysis showed that the PCB profile in hair was similar to that of internal tissues, although a gender difference was found for concentrations in hair relative to concentrations in internal tissues. Females (n = 6) were found to display strongly negative correlations (-0.78 ≤ r ≥ -0.55, 0.065 ≤ p ≥ 0.26 for sum PCBs) while males (n=5) showed weaker positive correlations (0.21 ≤ r ≥ 0.84, 0.077 ≤ p ≥ 0.74 for sum PCBs). Even though most correlations were strong they were not significant (p>0.05), but this was due to small sample sizes. Further research is thus necessary to draw more definitive conclusions.