Red Domino

https://digitalcommons.library.umaine.edu/mmb-vp/6108/thumbnail.jp

Effects of excitonic diffusion on stimulated emission in nanocrystalline ZnO

We present optically-pumped emission data for ZnO, showing that high excitation effects and stimulated emission / lasing are observed in nanocrystalline ZnO thin films at room temperature, although such effects are not seen in bulk material of better optical quality. A simple model of exciton density profiles is developed which explains our results and those of other authors. Inhibition of exciton diffusion in nanocrystalline samples compared to bulk significantly increases exciton densities in the former, leading, via the nonlinear dependence of emission in the exciton bands on the pump intensity, to large increases in emission and to stimulated emission

Exciton-polariton behaviour in bulk and polycrystalline ZnO

We report detailed reflectance studies of the exciton–polariton structure of thin film polycrystalline ZnO and comparison with bulk crystal behaviour. Near-normal incidence reflectance spectra of these samples are fitted using a two-band dielectric response function. Our data show that the reflectance data in polycrystalline ZnO differ substantially from the bulk material, with Fabry–Perot oscillations at energies below the transverse A exciton and above the longitudinal B exciton in the films. In the strong interaction regime between these energies no evidence is seen of the normally rapid oscillations associated with the anomalous waves. We demonstrate that the strong interaction of the damped exciton with the photon leads to polaritons in this region with substantial damping such that the Fabry–Perot modes are eliminated. Good qualitative agreement is achieved between the model and data. The importance of the polariton model in understanding the reflectance data of polycrystalline material is clearly see

Evaluation of vermifiltration of cassava effluent using earthworm

The objective of this study was to evaluate the vermifiltration of different cassava effluent concentrations using of earthworms by applying standard methods. Results for physiochemical parameters before treatment ranges from 3. 91 to 5.94, 28.6to 28.7(μS/cm), 12480 to 13999 (mg/l), 7900 to 9511(mg/l), 168 to 207(mg/l), 8068 to 9718(mg/l), 225 to 284(mg/l), 114 to 132(mg/l), 1040 to 1680(mg/l), 400 to 540(mg/l), 52 to 72(mg/l), 24 to 40(mg/l), 20 to 30(mg/l), 33 to 65(mg/l) for pH, Temperature, EC, TDS, TSS, TS, COD, BOD, Hardness, chlorine, calcium, magnesium, sodium and potassium, respectively, while after treatment ranges from 6.45 to 10.1, 28.6 to 29, 12021 to 12621(μS/cm), 8100 to 9846(mg/l), 199 to 211(mg/l), 8299 to 10057(mg/l), 260 to 291(mg/l), 140 to 120(mg/l), 760 to 1160(mg/l), 260 to 440(mg/l), 48 to 62(mg/l), 22 to 39(mg/l), 19 to 28(mg/l), 31 to 60(mg/l) for pH, Temperature, Electrical Conductivity (EC), TDS, TSS, TS, COD, BOD, Hardness, Chlorine, Calcium, Magnesium, Sodium and Potassium, respectively, across the different concentrations (100%, 75%, 50% and 25%) of cassava effluent. It was therefore, observed that the use of earthworm in the treatment of cassava effluent was effective, though, it could not treat the cassava effluent to the acceptable World Health Organization (WHO) Standards for irrigation use.Keywords: physiochemical characteristics, cassava, effluent concentrations, vermifiltratio

Evidence of hypoxic foraging forays by yellow perch ( Perca flavescens ) and potential consequences for prey consumption

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91146/1/FWB_2753_sm_fS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/91146/2/j.1365-2427.2012.02753.x.pd