Temperature-dependence of exciton radiative recombination in (Al,Ga)N/GaN quantum wells grown on a-plane GaN substrates

This article presents the dynamics of excitons in a-plane (Al,Ga)N/GaN single quantum wells of various thicknesses grown on bulk GaN substrates. For all quantum well samples, recombination is observed to be predominantly radiative in the low-temperature range. At higher temperatures, the escape of charge carriers from the quantum well to the (Al,Ga)N barriers is accompanied by a reduction in internal quantum efficiency. Based on the temperature-dependence of time-resolved photoluminescence experiments, we also show how the local disorder affects the exciton radiative lifetime at low temperature and the exciton non-radiative lifetime at high temperature.We acknowledge financial support from the Swiss National Science Foundation through Project No. 129715 and from the Polish National Science Center (Project DEC-2011/ 03/B/ST3/02647). The work was partially supported by the European Union within European Regional Development Fund through Innovative Economy Grant No. POIG.01.01.02-00-008/08. P.C. also acknowledges financing from the European Union Seventh Framework Program under grant agreement No. 265073

Finite Fault Analysis and Near Field Dynamic Strains and Rotations due to the 11/05/2011 (Mw5.2) Lorca Earthquake, South-Eastern Spain

The 11/5/2011 Lorca, Spain earthquake (Mw5.2) and related seismicity produced extensive damage in the town of Lorca and vicinity. During these earthquakes, evidence of rotations and permanent deformations in structures were observed. To analyze these aspects and study the source properties from the near field, the displacement time histories were obtained including the static component at Lorca station. Displacement time histories were computed by an appropriate double time integration procedure of accelerograms. Using these data, the foreshock and mainshock slip distributions were calculated by means of a complete waveform kinematic inversion. To study the dynamic deformations, the 3D tensor of displacement gradients at Lorca station was first estimated by a single station method. Using the finite fault inversion results and by means of a first order finite difference approach, the dynamic deformations tensor at surface was calculated at the recording site. In order to estimate the distribution of the peak dynamic deformations, the calculation was extended to the close neighboring area of the town. The possible influence of the near-field deformations on the surface structures was analyzed.Comment: 29 pages, 8 figure

Interface forces measurement in laminated composites

In laminated composites, interfaces are the transfer spots of mechanical charges, mechanical over-stresses adaptations and energy dissipations. We have realised an experiment in order to observe the visco-elastic interface behaviour of a laminated composite. Between two composite plies of a multilayer cantilever beam, piezoelectric PVDF thin films are bonded. The voltage signals generated by the piezoelectric elements are dependant of the expected interlaminar stresses. The data acquisition system program of the signals is written with LabVIEW^{\fontsize{6}{8}\selectfont{\hbox{\textregistered}}}. The results of the experiment validate the parameters of finite element simulations realised on the dynamic behaviour of the cantilever beam

Observations of Electromagnetic Radiation in the Central Apennines Seismic Region

In recent years, continuous radio-noise recording is in use at many geophysical observatories, in order to detect possible earthquake precursors and/or coseismic signals. The recordings obtained indicate that electromagnetic radiation (e.g., in the range of 10-40 kH) can indeed be treated as seismic precursor. We present here the examples of successful prediction observation, which we have obtained in the Central Apennines region at the l'Aquila Observatory (Polish-Italian cooperation). A short discussion on relation between the evolution of stresses (dislocation dynamics) and electromagnetic emission supplements this paper.Published43-532.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attiveN/A or not JCRreserve

INFLUENCE OF THE MULTIDRUG TRANSPORTER INHIBITORS ON THE ACTIVITY OF KV1.3 VOLTAGE-GATED POTASSIUM CHANNELS

Using the whole-cell patch-clamp technique, the influence of selected multidrug resistance modulators, both plant-derived compounds and derivatives on the activity of voltage-gated potassium channels Kv1.3 was investigated. Twelve compounds with phenolic and terpenic structures were tested: the stilbenes piceatannol (1) and its tetramethoxy (2) and tetracetoxy (3) derivatives, the flavonoids naringenin (4) and its methylated derivatives: naringenin-4',7-dimethylether (5) and naringenin-7-methylether (6), and aromadendrin (7), the coumarins esculetin (13) and scopoletin (9) and ent-abietane diterpenes, helioscopinolide B (10) and its 3 beta-acetoxy derivative (11) and helioscopinolide E (12). The studies were performed on a model system with Kv1.3 channels endogenously expressed in human T lymphocytes. Obtained data provide evidence that compounds 2, 5 and 6 applied at 30 mu M inhibited the amplitude of recorded currents to 31%, 4% and 29% of its control value, respectively. On the other hand, compounds 3, 4, 7-12 (at 30 mu M) and compound 1 (at 40 mu M) did not affect significantly the channel activity. These results indicate that some methoxy-derivatives of the tested compounds are effective inhibitors of Kv1.3 channels. Since the inhibition of Kv1.3 channels may inhibit the proliferation of prostate, breast and colon cancer cells expressing these channels, the channel inhibitors may exert an anti proliferative action. This action combined with a simultaneous modulation of the multidrug resistance may be significant for a potential application of these compounds in cancer chemotherapy.. - Polish Ministry of Research and University Education [N 301 2549 33]; Science and Technology Foundation (FCT), Portugal. - The Authors would like to express best thanks to the colleague from the Biophysics Department of Wroclaw Medical University - Dr. Andrzej Pola, for a kind help in providing blood samples for isolation of T lymphocytes. This work was supported by the Polish Ministry of Research and University Education (Ministerstwo Nauki i Szkolnictwa Wyzszego) Grant no N 301 2549 33 (A.T. and K.M.) and by the Science and Technology Foundation (FCT), Portugal (N.D. and M-J.U.F.)