Time-Resolved Electroluminescence of AlGaN-Based Light-Emitting Diodes with Emission at 285 nm

We present a study on the time evolution of the electroluminescence(EL)spectra of AlGaN-based deep ultraviolet light-emitting diodes(LEDs) under pulsed current pumping. The ELspectra peaks at 285 nm and 330 nm are found to result from recombination involving band-to-band and free carriers to deep acceptor level transitions. The 330 nm long-wavelength transitions to deep acceptor levels in the p-AlGaN layer as well as the nonradiative processes significantly influence the LED internal quantum efficiency

Chemical composition study of vanadium pentoxide xerogels doped by bovine albumin

Metal–bioorganic compounds of vanadium pentoxide and bovine serum albumin (BSA) (Fraction V) were obtained by using sol–gel method. Series of the samples (BSA)xV2O5 nH2O, where x ¼ 0, 0.01 and 0.001, were originally produced by the synthesis of vanadium pentoxide xerogels and subsequent blending with water-dissolved BSA in appropriate molar ratios. It was evident that the gelation process does not occur for x > 0:01. For the X-ray photoelectron spectroscopy (XPS) studies, the thin layers of these materials were prepared by drying the gel onto the glass and mica substrates. The surface morphology of the samples was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. It follows from the analysis of experimental XPS spectra of (BSA)xV2O5 nH2O that the nitrogen ions in pure albumin and in (BSA)0:01V2O5 nH2O are present in imine, amine and protonated amine groups. The additional protonated amine arises when the concentration of albumin in (BSA)xV2O5 nH2O is low (x ¼ 0:001). Increasing the amount of albumin results in decrease of the number of oxygen ions bonded to vanadium. At the same time (with increase of albumin), the component of oxygen bounded to carbon and nitrogen is increasing. In the samples with greater amount of albumin, the reduction of vanadium ions occurs. This means that the trivalent and tetravalent vanadium ions are present together with pentavalent onesVytauto Didžiojo universitetasŠvietimo akademij

Ancillary study to the PREFER trial: A descriptive study of participants' patterns of self-monitoring - Rationale, design and preliminary experiences

Background: The treatment of obesity, marked by a high rate of recidivism, lacks strategies that sustain the improved lifestyle behaviors that led to the weight loss. Self-monitoring, a behavioral strategy to increase awareness of one's behavior, is the cornerstone of behavioral treatment in weight loss management. However, adherence to self-monitoring is less than ideal. The actual patterns of self-monitoring of eating behaviors in weight loss treatment programs have not been studied previously; if done, these data could provide information on how self-monitoring patterns affect weight loss and if interventions can be developed that address deficits in self-monitoring. Technology now permits an instrumented paper-and-pencil diary to record the real time of individuals' self-monitoring behaviors (invivodata, inc.), thus providing more information about self-reported behaviors. This technology differs from PDA based products (ex. e-diary, e-trials, logpad, PICS) because, to the user, it is no different from a standard paper-and-pencil diary. Methods: The purposes of this ancillary study are: (1) to describe the electronically recorded patterns of self-monitoring of eating behaviors by weight-loss study participants; (2) compare reported vs. electronically recorded self-monitoring; and (3) examine the relationship between the electronically validated adherence to self-monitoring goals and success in weight loss in a sub-sample of participants in the PREFER study. This paper describes the design, methods and preliminary 6-month results. Results: Preliminary results reveal that participants frequently report recording their eating behavior during times when the binder was not opened. Two examples of data are shown that demonstrate the lack of concordance between the self-reported and the electronically recorded data. Conclusions: These unobtrusively collected electronic data can lead to the development of strategies that can promote improved adherence to self-monitoring. © 2005 Elsevier Inc. All rights reserved