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Zinc oxide (ZnO) and aluminum-doped zinc oxide (ZnO:Al) thin films were deposited onto glass and silicon substrates by RF magnetron sputtering using a zinc-aluminum target. Both films were deposited at a growth rate of 12.5 nm/min to a thickness of around 750 nm. In the visible region, the films exhibit optical transmittances which are greater than 80%. The optical energy gap of ZnO films increased from 3.28 eV to 3.36 eV upon doping with Al. This increase is related to the increase in carrier density from 5.9 × 1018 cm-3 to 2.6 × 1019 cm-3. The RMS surface roughness of ZnO films grown on glass increased from 14 to 28 nm even with only 0.9% at Al content. XRD analysis revealed that the ZnO films are polycrystalline with preferential growth parallel to the (002) plane, which corresponds to the wurtzite structure of ZnO.
The knowledge of
liminology can be applied in studies of trophic state indexes and morfoedaphic
indexes as factors for determining the inference fish production in reservoirs.
This work is based on the hypothesis of the trophic cascade relations,
particularly related to bottom-up and top-down effect in Itaipu Reservoir
(Brazil). Using the data available by Itaipu, from 1999 to 2004, analyzes of
multiple regressions were accomplished to determine the relationships of the
dependent and independent variables. We applied the trophic state indices (TSI)
based on readings Secchi disk, total phosphorus and chlorophyll-a density for obtaining TSI medium.
Morfoedaphic index was calculated based on the reading of the concentration of
dissolved solids and the inference of fishing yield, from this index. The
average results of the trophic state indices indicate an oligotrophic status
for the entire reservoir as well as for the riverine, transition and lacustrine
zones separately. The fish was yieldn Estimated by the relation with
cyanobacteria concentration, and this was the best variable que explained this
prediction. The use of the morfoedaphic index (MEI), with the recorded catch
data, predictive models can generate que estimate the fishing yield in the
Itaipu Reservoir. The relations of MEI with chlorophyll-a and water
transparency que Indicate this index may be a good predicting factor for future