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High throughput screening using the recombinant human TRPV1 receptor was used to identify a series of pyridinylpiperazine ureas (3) as TRPV1 vanilloid receptor ligands. Exploration of the structure−activity relationships by parallel synthesis identified the essential pharmacophoric elements for antagonism that permitted further optimization via targeted synthesis to provide a potent orally bioavailable and selective TRPV1 modulator 41 active in several in vivo models.

A GaInN quantum-well structure with an average In-concentration of 16%, grown by metal organic chemical vapor deposition (MOCVD) on a SiC substrate, was studied by transmission electron microscopy (TEM) and photoluminescence spectroscopy (PL) before and after an one-hour annealing treatment at 980 °C. Due to the heat treatment, the formation of In-rich clusters with extensions between 10 nm and 100 nm and In-concentrations above 80% was observed. Nevertheless, the PL exhibits a blue shift in the PL-peak energy of about 90 meV compared to the as-grown sample and do not show a significant influence of the In-rich clusters on the emission wavelength.

GaInN/GaN islands have been grown by metalorganic vapor phase epitaxy (MOVPE) on SiC substrates. We report on the influence of different growth parameters, such as growth temperature, growth rate or the quantity of deposited material on the growth of such dots. The characterisation of these structures has been done by using atomic force microscopy (AFM) and transmission electron microscopy (TEM). Up to now, the maximum density obtained is 1010dots/cm2at 660 °C at a growth rate of 4 ML/min.

For group III nitride‐based lasers a new approach to realise DFB lasers and arrays is presented. Laterally coupled DFB (LC‐DFB) lasers are realised to minimise processing‐induced damage and to enable post‐processing adjustment of DFB laser parameters according to the material parameters achieved after epitaxial growth. These DFB laser arrays enable one to measure the threshold and the refractive index of electrically pumped DFB lasers over a wavelength emission range of 6 nm. DFB emission is demonstrated up to 70 °C and simultaneously a small temperature shift of the DFB mode. A significantly smaller tuning range is observed compared to optically pumped DFB lasers as well as a significantly red‐shifted gain region. Furthermore, the dispersion relation gradient determined, dneff/dλ, appears significantly steeper (by a factor of six) than in the optically pumped case. These effects are attributed to incompletely screened polarisation fields in electrically pumped InGaN/GaN lasers.

InGaN/GaN quantum dots are currently of major interest in basic research and for device application. If material of sufficient quality is available, light emission from blue to green is already possible in this system. We report here on our InGaN/GaN quantum dots grown by metalorganic vapour phase epitaxy (MOVPE). The dot formation was examined using atomic force microscopy (AFM). This work is focused on photoluminescence (PL) and cathodoluminescence (CL) measurements of these InGaN dots. To prove the existence of quantum dots in capped samples we have performed power-dependent PL and found evidence of state filling, which is typical for quantum dots. These results were confirmed with CL measurements on structured samples.

InGaN/GaN quantum dots are currently of major interest in basic research and for device application. If material of sufficient quality is available, light emission from blue to green is already possible in this system. We report here on our InGaN/GaN quantum dots grown by metalorganic vapour phase epitaxy (MOVPE). The dot formation was examined using atomic force microscopy (AFM). This work is focused on photoluminescence (PL) and cathodoluminescence (CL) measurements of these InGaN dots. To prove the existence of quantum dots in capped samples we have performed power-dependent PL and found evidence of state filling, which is typical for quantum dots. These results were confirmed with CL measurements on structured samples.

We design, as a possible device structure for optic–optic switching, an electronic three level system with distributed electronic wave function and localised hole function on the basis of the quantum mechanical tunnel effect between asymmetric coupled double quantum wells (ASC-DQWs). After strong optical excitation the ASC-DQW shows a strong dipole field which induces strong Stark shifts in the whole electronic structure. The dipole fields can be enhanced and used for coupling if the ASC-DQW is patterned in wire or dot structures. We demonstrate by periodic wire arrays light-induced Stark shifts of the electronic states and thus switching. Due to the short tunnelling times of the electrons in the three level system of the ASC-DQW time responses of the Stark shift in the ps range are possible.

We give conclusive experimental evidence that spin-dependent exciton–exciton interaction processes can be altered by directly modifying the spatial exciton structure applying an electric field. The previously observed energy splitting in spin-polarized, dense exciton gases can be varied by the electric field from a maximum of 4 meV to 0 meV. On the basis of an earlier developed theoretical model it is seen that inter-exciton scattering processes dominating at zero field are quenched and others are enhanced on increasing the field strength.

A comprehensive study of pp and np Bremsstrahlung based upon the potential model formalism was initiated to explore properties of two nucleon t-matrices. Underlying potentials of t-matrices either were generated by Gelfand-Levitan-Marchenko inversion of the latest NN phase shifts or are the Paris and Bonn-R potentials. The Bremsstrahlung amplitudes associated with external, internal and exchange currents, by exact treatment of the Coulomb potential in on- and half-off-shell t-matrices, and the relativistic spin corrections were all computed and for both coplanar and non coplanar geometries. The results are a successful analysis of ppγ TRIUMF data and allow us to set experimental boundaries for planned new experiments. They also give a perspective of the off-shell t-matrix information inherent in this reaction.

Charge-neutral excitons in semiconductor quantum dots (QDs) have a small finite energy separation caused by the anisotropic exchange splitting. Coherent excitation of neutral excitons will generally excite both exciton components, unless the excitation is parallel to one of the dipole axes. We present a polaron master equation model to describe two-exciton pumping using a coherent continuous wave pump field in the presence of a realistic anisotropic exchange splitting. We predict a five-peak incoherent spectrum, namely a Mollow quintuplet under general excitation conditions. We experimentally confirm such spectral quintuplets for In(Ga)As QDs and obtain very good agreement with theory.

The optical properties of metal-organic vapor phase epitaxy grown AlyInxGa1−x−yN quantum dot structures have been studied by time-resolved photoluminescence experiments. We investigated the recombination dynamics of the photo-exited carriers in dependence of the growth parameters such as aluminium flow and the duration of the growth interruption after the dot deposition. Our results confirm the presence of localized states, where the degree of localization is strongly dependent on the growth conditions. To describe this behavior, we propose a band structure with coupled potentials for these nanostructures. Finally, we demonstrate state filling to prove the zero-dimensional character of the strongly localized states in our quaternary quantum dots.

Within a research targeted toward the synthesis and biological evaluation of psoralen analogues for pharmaceutical applications, the 7‐hydroxycoumarins (I) and (IV) are condensed with alkylating agents such as (II) and (V) in acid media to give the title compounds (III) and (VI).

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.