Heavily Doped, Charge-Balanced Fluorescent Organic Light-Emitting Diodes from Direct Charge Trapping of Dopants in Emission Layer.

We studied the effect of direct charge trapping at different doping concentrations on the device performance in tris(8-hydroxyquinoline) aluminum (Alq3):10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-(1)-benzopyropyrano(6,7-8-i,j)quinolizin-11-one (C545T) as a host-dopant system of a fluorescent organic light-emitting diode. With increasing C545T doping concentration, trap sites could lead to the promotion of hole injection and the suppression of electron injection due to the electron-transport character of Alq3 host for each carriers, as confirmed by hole- and electron-only devices. Direct charge injection of hole carriers from the hole transport layer into C545T dopants and the charge trapping of electron carriers are the dominant processes to improve the charge balance and the corresponding efficiency. The shift of the electroluminescence (EL) spectra from 519 nm to 530 nm was confirmed the exciton formation route from Förster energy transfer of host-dopant system to direct charge trapping of dopant-only emitting systems. Variation in the doping concentration dictates the role of the dopant in the fluorescent host-dopant system. Even though concentration quenching in fluorescent dopants is unavoidable, relatively heavy doping is necessary to improve the charge balance and efficiency and to investigate the relationship between direct charge trapping and device performance. Heavy doping at a doping ratio of 6% also generates heavy exciton quenching and excimer exciton, because of the excitons being close enough and dipole-dipole interactions. The optimum device performance was achieved with a 4%-doped device, retaining the high efficiency of 12.5 cd/A from 100 cd/m(2) up to 15,000 cd/m(2).

Analysis of cell growth and gene expression of porcine adipose tissue-derived mesenchymal stem cells as nuclear donor cell.

In several laboratory animals and humans, adipose tissue-derived mesenchymal stem cells (ASC) are of considerable interest because they are easy to harvest and can generate a huge proliferation of cells from a small quantity of fat. In this study, we investigated: (i) the expression patterns of reprogramming-related genes in porcine ASC; and (ii) whether ASC can be a suitable donor cell type for generating cloned pigs. For these experiments, ASC, adult skin fibroblasts (AF) and fetal fibroblasts (FF) were derived from a 4-year-old female miniature pig. The ASC expressed cell-surface markers characteristic of stem cells, and underwent in vitro differentiation when exposed to specific differentiation-inducing conditions. Expression of DNA methyltransferase (DNMT)1 in ASC was similar to that in AF, but the highest expression of the DNMT3B gene was observed in ASC. The expression of OCT4 was significantly higher in FF and ASC than in AF (P < 0.05), and SOX2 showed significantly higher expression in ASC than in the other two cell types (P < 0.05). After somatic cell nuclear transfer (SCNT), the development rate of cloned embryos derived from ASC was comparable to the development of those derived using FF. Total cell numbers of blastocysts derived using ASC and FF were significantly higher than in embryos made with AF. The results demonstrated that ASC used for SCNT have a potential comparable to those of AF and FF in terms of embryo in vitro development and blastocyst formation.

The group velocity variation of Lamb wave in fiber reinforced composite plate.

Experimentally measured Lamb wave group velocities in composite materials with anisotropic characteristics are not the same as the theoretical group velocities which is calculated with the Lamb wave dispersion equation. This discrepancy arises from the fact that the angle between the group velocity direction and the phase velocity direction in anisotropic materials exists. Wave propagation in a composite material with anisotropic characteristics should be considered with respect to magnitude correction in addition to direction correction. In this study, S0 mode phase velocity dispersion curves are depicted with the variation of degree with respect to the fiber direction using a Lamb wave dispersion relation in the unidirectional, bidirectional, and quasi-isotropic composite plates. Slowness surface is sketched by the reciprocal value of the phase velocity curves. The magnitude and direction of the group velocity could be calculated from the slowness surface. The recalculated group velocities with consideration of the magnitude and direction from the slowness surface are compared with experimentally measured group velocities. The proposed method shows good agreements with theoretical and experimental results.

Predictors of outcome in geriatric patients with urinary tract infections.

A study was conducted to determine the prognosis of geriatric patients with urinary tract infections (UTIs) and identify clinical factors associated with adverse outcomes. This retrospective, cohort study identified elderly patients (age > or =65 years) presenting to an academic, urban Emergency Department (ED) during a 16-week period with UTI, suggested by urinalysis and pertinent symptoms. There were 37 demographic and clinical variables analyzed as potential predictors of outcome. Morbidity was defined as in-hospital death, Intensive Care Unit (ICU) admission, hospital length of stay (LOS) >2 days, or hospital intravenous (i.v.) antibiotics >2 days. Factors identified by univariate analysis were combined using multiple logistic regression to identify independent predictors of morbidity. There were 284 patients who met selection criteria. Thirteen patients (4.6%) died during hospitalization and 27 (9.5%) had ICU admission, 139 (48.9%) had LOS >2 days, and 75 (26.4%) had i.v. antibiotics >2 days. Multivariate analysis identified the following variables as independent predictors of adverse outcomes: mental status change, frequent UTIs, other nonurinary infections, abnormal temperature, tachycardia, hypotension, elevated BUN, hyperglycemia, elevated WBC, and relative neutrophilia. Regression models for adverse outcomes had sensitivities from 74.8% to 96.2% and specificities from 31.1% to 69.0%. In conclusion, this study defines high rates of morbidity for geriatric patients with UTIs and describes predictive variables that may help identify low-risk patients. These data may lay the foundation for determining specific guidelines for disposition of this high-risk patient population.