Enhancement of the luminance efficiency for top-emitting DB-PPV polymer light-emitting diodes with Ca/Ag cathode

The enhancement of the luminance efficiency of the top-emitting 2,3-dibutoxy-1,4-polyphenylene vinylene (DB-PPV) polymer light-emitting diodes (PLEDs) with Ca/Ag cathode has been investigated in this work. The luminance efficiency of 2.9 cd A⁻¹ (at 10 mA) for the thickness of Ca/Ag cathode of 10/15 nm is achieved by our devices. In this paper, partially oxidized CaO_x film is proposed to have the capability of hole-blocking as well as the buffer layer on condition of the suitable Ag thickness of Ca/Ag cathode. The tuning ability of colors by simply adjusting the thickness of the DB-PPV emitting layer is available for the devices.     

Urban Particle Capture in Bioretention Media. II: Theory and Model Development

As a novel stormwater best-management practice, using a soil/sand/mulch mixture to capture urban pollutants while promoting infiltration, the unique media composition renders bioretention significantly different from conventional sand filters. In this work, a three-layer model is presented to describe particulate capture in bioretention media employing parameter calibration and presensitivity analysis. Since the fine size of bioretention media strictly limits the particulate penetration distance, the media column is modeled as a pristine zone (bottom), a working zone (middle), and a cake zone (top). Mechanisms of both depth filtration and cake filtration are examined through mass balances, which show that both are significant. The developed resistance of each layer due to solid deposition was also estimated. Experimental data for different media/TSS-type combinations of selected experimental trials were used in parameter calibration. The calibrated model successfully predicted the effluent TSS and media hydraulic conductivity of subsequent trials with appropriate boundary and initial conditions as input. A weighted combination of calibrated parameters from different TSS types also agreed well with media behavior for treating a complex TSS mixture. The results of media replacement (top removal and refill) simulation also reasonably fit experimental data. Using proper assumptions, a long-term scenario analysis for permeability reduction was performed for a field bioretention facility. Based on modeling results, this study recommends a shallow bioretention media depth design, an annual or biannual field inspection schedule, and periodic media replacement maintenance.     

Effect of discharge power density on the properties of Al and F co-doped ZnO thin films prepared at room temperature

ZnO transparent conducting thin films co-doped with aluminium and fluorine (AZO:F) were prepared on glass substrates by RF magnetron sputtering at room temperature. The effect of discharge power density on the microstructure, surface morphology, electrical and optical properties was investigated. From XRD analysis, it was revealed that the intensity of (002) favoured orientation of ZnO films increased with power density from 2.6 to 6.1?W/cm² and then turned to a randomly orientated structure as power density continuously increased to 7.8?W/cm². The film prepared at 6.1?W/cm² showed a better crystallization and microstructure with larger, pyramid-like grains that were approximately 180?nm long and 90?nm wide. As a result, the electrical resistivity of the AZO:F films had a minimum of 4.1?×?10^?4???cm. The improvement in the electrical resistivity of AZO:F films was due to the increase in carrier concentration from 8.8?×?10²⁰ to 1.38?×?10²¹?cm^?3 and the mobility from 5.8 to 11.8?cm² V^?1 s^?1. The increase in carrier concentration with power density was also found to affect the optical property of the films due to the Moss-Burstein shift.     

Dual inhibitions of lemon balm (<Emphasis Type="Italic">Melissa officinalis</Emphasis>) ethanolic extract on melanogenesis in B16-F1 murine melanocytes: Inhibition of tyrosinase activity and its gene expression

The effects of wild type and UV-irradiated lemon balm (Melissa officinalis) ethanolic extracts (MOE and UMOE) on melanogenesis in vitro were examined. UMOE showed potent antioxidant activity and significantly inhibited the mushroom and melanocyte tyrosinase activity, and lowered cellular melanin content by 49% at 200 μg/mL in B16-F1 melanocytes. The key gene and protein expression of tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2 were reduced (−73% for TRP-1 protein at 200 μg/mL UMOE, p<0.05). MOE showed similar results to a slightly lesser degree. We found that myo-inositol, a major compound in lemon balm extracts, significantly reduced cellular melanin synthesis and its effect was greater than arbutin at 1 mM. These suggest that both MOE and UMOE have anti-melanogenic role by both direct inhibition of tyrosinase and down-regulation of gene expressions in melanogenesis. UV-irradiation slightly improved the anti-melanogenic activities. UMOE may be useful as natural anti-melanogenic biomaterials for functional foods and cosmetics.     

Wet-etch texturing of ZnO:Ga back layer on superstrate-type microcrystalline silicon solar cells

Surface wet etching is applied to the ZnO:Ga (GZO) back contact in μc-Si thin film solar cells. GZO transparency increases with increasing deposition substrate temperature. Texturing enhances reflective scattering, with etching around 5-6 s producing the best scattering, whereas etching around 5 s produces the best fabricated solar cells. Etching beyond these times produces suboptimal performance related to excessive erosion of the GZO. The best μc-Si solar cell achieves FF=68%, V_OC=471 mV and J_SC=21.48 mA/cm² (η=6.88%). Improvement is attributed to enhanced texture-induced scattering of light reflected back into the solar cell, increasing the efficiency of our lab-made single μc-Si solar cells from 6.54% to 6.88%. Improved external quantum efficiency is seen primarily in the longer wavelengths, i.e. 600-1100 nm. However, variation of the fabrication conditions offers opportunity for significant tuning of the optical absorption spectrum.     

Water Quality Improvement through Reductions of Pollutant Loads Using Bioretention

As an increasingly adopted storm-water best management practice (BMP) to remedy hydrology and water quality impairment from urban development, bioretention facilities need rigorous investigation to quantify performance benefits and to allow design improvements. This study examines water quality improvements [total arsenic, total cadmium, chloride, total chromium, total and dissolved copper, E. coli, fecal coliform, lead, mercury, nitrogen species, oil and grease, phosphorus, total organic carbon (TOC), total suspended solids, and total zinc] via monitoring for a 15-month period at two bioretention cells in Maryland. Both bioretention cells effectively removed suspended solids, lead, and zinc from runoff through concentration reduction. Runoff volume reduction promotes pollutant mass removal and links BMP water quality benefits with hydrologic performance. From a load perspective (kg/ha?year), all but TOC at one cell showed pollutant reduction. Bioretention effluents exhibited good water quality for all significant pollutants except for nitrate, copper, and phosphorus in one cell, the latter two of which may be attributed to media organic matter dissolution. Copper dissolved/particulate analyses showed that significant changes in copper speciation behavior result from transport through the bioretention media.     

Continuously tunable photopumped 1.3-μm fiber Fabry-Perotsurface-emitting lasers

Continuously tunable, single-frequency, optically pumped semiconductor-fiber lasers are demonstrated that embody a half-cavity, vertical-cavity surface-emitting laser within a fiber Fabry-Perot cavity. Continuous wavelength tuning over 40 nm at 1300-nm wavelength region is obtained under continuous-wave operation     

Near 10 μm intervalence subband optical transitions in p-type In0.49Ga0.51P-GaAs quantum well structures

In this paper, the intervalence subband optical transitions in p-doped In_0.49Ga_0.51P-GaAs quantum well structures are theoretically investigated. The intervalence subband optical transitions are modelled by the multiband effective mass equations incorporating the unitary transformation numerical method. The present formalism is based on the k&oarr;·P&oarr; perturbation theory as done to date but contains two significant improvements: 1) a more efficient treatment of band structures, optical matrix elements, and absorption coefficients; and 2) the avoidance of zero-order Bloch function approximation for calculating the intervalence subband optical matrix elements and absorption spectra in favour of correcting the first-order perturbation theory in order to take the remote band effects into account. Both of the requirements, especially the latter, play a very important role in gaining qualitative insight and obtaining quantitative calculation of optical selection rules. A systematical study of the subband structures, intervalence subband optical matrix elements, and absorption spectra is made for p-doped In_0.49Ga _0.51P-GaAs quantum wells, and a design guideline for near 10 μm infrared absorption is also discussed     

Dihydrolipoic Acid Induces Cytotoxicity in Mouse Blastocysts through Apoptosis Processes

α-Lipoic acid (LA) is a thiol with antioxidant properties that protects against oxidative stress-induced apoptosis. LA is absorbed from the diet, taken up by cells and tissues, and subsequently reduced to dihydrolipoic acid (DHLA). In view of the recent application of DHLA as a hydrophilic nanomaterial preparation, determination of its biosafety profile is essential. In the current study, we examined the cytotoxic effects of DHLA on mouse embryos at the blastocyst stage, subsequent embryonic attachment and outgrowth in vitro, in vivo implantation by embryo transfer, and early embryonic development in an animal model. Blastocysts treated with 50 μM DHLA exhibited significantly increased apoptosis and a corresponding decrease in total cell number. Notably, the implantation success rates of blastocysts pretreated with DHLA were lower than that of their control counterparts. Moreover, in vitro treatment with 50 μM DHLA was associated with increased resorption of post-implantation embryos and decreased fetal weight. Data obtained using an in vivo mouse model further disclosed that consumption of drinking water containing 100 μM DHLA led to decreased early embryo development, specifically, inhibition of development to the blastocyst stage. However, it appears that concentrations of DHLA lower than 50 μM do not exert a hazardous effect on embryonic development. Our results collectively indicate that in vitro and in vivo exposure to concentrations of DHLA higher than 50 μM DHLA induces apoptosis and retards early pre- and post-implantation development, and support the potential of DHLA to induce embryonic cytotoxicity.     

Simple, low-cost, subsystem fabrication

We have successfully developed a simple and low-cost 1.9-GHz, 25-W power amplifier by using only one prematched 50-mm PHEMT with external matching circuits on a FR-4 PCB. As the output stage integrated with other driver stages and dc control circuits, a completed four-stage power-amplifier subsystem is also demonstrated. When operating at 38.5-dBm output power with /spl pi//4-DQPSK signal, the proposed power amplifier subsystem shows low distortion, with better than 75-dBc ACPR (adjacent-channel leakage power ratio) at 600 kHz and 79-dBc ACPR at 900 kHz offset from the center frequency, and is suitable for PHS 500-mW base-station applications.