Investigation of the energy transfer mechanism in OLEDs based on a new terbium β-diketonate complex

This study is focused on the contribution of radiative and non-radiative processes to the electroluminescence emission of OLEDs based on a new terbium(III) complex: {Tris(acetylacetonate)[1,2,5]thiadiazole[3,4-f][1,10]phenanthroline}terbium(III) or [Tb(ACAC)₃TDZP]. The effects of the energy transfer mechanism are discussed based on photoluminescence and electroluminescence measurements. The terbium complex showed an intense photoluminescence with high color purity in the green region, characteristics of the Tb(III) ion narrow line transitions. However, when used in a double-layer OLED its electroluminescence showed an orange broad band emission which can be attributed to the electrophosphorescence of the ligands and to an inefficient energy transfer from the organic ligand to the Tb(III) ion. Alternatively, devices with a Tb(III) complex acting as a dopant (7.6%) in a matrix of CBP used as the active layer showed an improvement in the energy transfer process, resulting in the appearance of the characteristic emission lines of the Tb(III) ion.     

Frequency locking in double-pumped dye laser

A jet-stream dye laser was pumped simultaneously by a CW argon laser and a high-power xenon ion laser. The frequency and bandwidth of the pulsed radiation obtained were locked to the CW radiation inside the folded cavity.     

Nondestructive burnup measurements by gamma-ray spectroscopy on spent fuel elements of the RP-10 research reactor

Gamma-ray spectroscopy is an important nondestructive method for the qualification of irradiated nuclear fuels. Regarding research reactors, the main parameter required in the scope of such qualification is the average burnup of spent fuel elements. This work describes the measurement, using nondestructive gamma-ray spectroscopy, of the average burnup attained by Material Testing Reactor (MTR) fuel elements irradiated in the RP-10 research reactor. Measurements were performed at the reactor storage pool area using ¹³⁷Cs as the only burnup monitor, even for spent fuel elements with cooling times much shorter than two years. The experimental apparatus was previously calibrated in efficiency to obtain absolute average burnup values, which were compared against corresponding ones furnished by reactor physics calculations. The mean deviation between both values amounts to 6%.     

Influence of the Processing Route on the Carbon Nanotubes Dispersion and Creep Resistance of 3YTZP/SWCNTs Nanocomposites

3YTZP matrix composites containing 2.5 vol% of single‐walled carbon nanotubes (SWCNT) were fabricated by Spark Plasma Sintering (SPS) at 1250°C, following different processing routines with the aim of optimizing the SWCNTs dispersion throughout the ceramic matrix. Microstructural characterization of the as‐fabricated samples has been performed by means of scanning electron microscopy (SEM). The specimens have been crept at 1200°C to correlate creep resistance and SWCNTs distribution. There are no creep experimental results on these nanocomposites reported in literature. Mechanical results show that the incorporation of SWCNTs into a 3YTZP matrix produces an increase in the strain rate at high temperature with respect to monolithic zirconia. The creep resistance of these nanocomposites decreases with the improvement of the SWCNTs dispersion, where a smaller SWCNTs agglomerate size and consequently a higher concentration of carbon nanotubes surrounding the 3YTZP grain boundaries is found. This fact indicates that SWCNTs act as a lubricant making grain‐boundary sliding easier during deformation of these composites.     

Physical characteristics of polymer complexes in suspension obtained from cellulosic latexes with ondansetron

Ondansetron is a carbazol with antiemetic properties. It is used primarily to control nausea and vomiting caused by cytotoxic chemotherapy and radiotherapy, as well as in postoperative vomiting in gynecological surgery. Ondansetron has a half-life of approximately 4 h, hence it is a matter of great interest to determine the ideal conditions for the formation of a drug-polymer complex in order to prolong the duration of the therapeutic action. A stability study of the active drug was first carried out on each of the polymers (Aquateric and Aquacoat). The adsorption of ondansetron on the lattices was determined with respect to time, pH and concentration. The results obtained suggest that both polymers are suitable as drug carriers for the controlled-release formulations obtained. We conclude that an acid pH is evidently fundamental in the adsorption process of this drug in the latexes. Moreover, the Aquateric latex would seem to be the best-suited polymer to use as a vehicle for drug delivery.     

Kinetics of thermal degradation of thiamine and surface colour in canned tuna

Summary The kinetics of thermal degradation of thiamine and surface colour (lightness measured as Hunter L-value) in canned white tuna were determined using an unsteady-state experimental procedure. Kinetic parameters were calculated by weighted non-linear regression considering a first-order kinetic model with a dependence of the kinetic coefficient (D) with temperature of the Thermal Death Time (TDT) type. Mass-average retentions of thiamine were calculated using a mathematical model which takes into account the non-uniform and unsteady distribution of temperature inside the container during thermal processing. The high correlation obtained between the predicted and the observed retention values and the small confidence intervals found for the kinetic parameters indicate a high statistical reliability. The kinetic model thus determined permits the simulation and optimization of the process resulting in a better quality of the final product.

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Kinetik des Abbaus von Thiamin und der Oberflächenfarbe von Dosenthunfisch

Zusammenfassung Die Kriterien der Wärmedegradation von Thiamin und der Oberflächenfarbe (Messung der Helligkeit mit dem Hunter-Wert L) in Konserven mit weißem Thunfisch werden mittels eines experimentellen Vorgehens von nicht-stationärem Typ bestimmt. Die kinetischen Parameter werden mit nicht-linearer, beschwerter Regression kalkuliert, wobei man einen kinetischen Koeffizienten D mit der Temperatur des Typs TDT bedenken muß. Für die Berechnung der durchschnittlichen Massenerhaltung von Thiamin benutzt man ein mathematisches Modell, das die nicht-uniforme und nichtbeständige Verteilung der Temperatur im Behälter während des Prozesses berücksichtigt. Die erhaltene starke Wechselbeziehung zwischen den vorhergesagten und den beobachteten Werten und zwischen den geringen Konfidenz-Intervallen, die für die kinetischen Parameter gefunden wurden, belegt eine hohe statistische Zuverlässigkeit. Das so bestimmte kinetische Modell erlaubt es, den Prozeß zu simulieren und zu optimieren, mit dem Ziel, die endgültige Qualität des Produktes zu verbessern.

     

Quantum statistical properties of an FEL amplifier

We discuss the problem of photon quantum statistics of a single particle free-electron laser (FEL) amplifier in the small-signal cold beam regime to first order in the electron quantum recoil. The initial radiation wave is an arbitrary coherent state. We show that Glauber coherence is not preserved by the FEL interaction if the initial coherent state is not the vacuum, even if we neglect the electron quantum recoil (absence of gain). We evaluate the first two moments of the final photon distribution and find sub- (super)-Poissonian photon statistics for a negative (positive) resonance parameter.     

Analysis of fish and squid myofibrillar proteins by capillary sodium dodecyl sulfate gel electrophoresis: actin and myosin quantification

 A capillary electrophoretic method for the separation and quantification of fish and squid myofibrillar proteins was developed. The method uses sodium dodecyl sulfate and β-mercaptoethanol for solubilization and analysis of myofibrillar protein subunits. The separation of the different polypeptides is achieved by the sieving effect of the gel inside the capillary. A calibration curve for myosin heavy chain and actin UV absorbance quantification of these proteins was developed. Received: 2 November 1999 / Revised version: 16 February 2000