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ZnO thin-film transistors (TFTs) were built on glass substrates. The device with a top gate configuration operates in the depletion mode. The ZnO channel was grown by metalorganic chemical vapor deposition (MOCVD) on glass at low temperature. SiO 2 was used as the gate dielectric. The TFT has an on/off ratio of $4.0 · 10 4 and a channel field-effect mobility of $4.0 cm 2 /V s. The average transmittance of the ZnO film in the visible wavelength is $80%. To compare the characteristics of the TFTs prepared by using a poly-ZnO and epitaxial-ZnO channel, an epi-ZnO TFT with the same configuration and dimensions was made on an r-Al 2 O 3 substrate. The epi-ZnO TFT shows higher field-effect mobility of $35 cm 2 /V s and on/off ratio of $10 8 .

In this paper, the authors investigate the use of an applied AC electric field and microchannel surface heterogeneities to carry out the microfluidic mixing of two-dimensional, time-dependent electroosmotic flows. The time-dependent flow fields within the microchannel are simulated using the backwards-Euler time-stepping numerical method. The mixing efficiencies obtained in microchannels with two different patchwise surface heterogeneity patterns are investigated. In general, the results show that the application of an AC electric field significantly reduces the required mixing length compared with the use of a DC electric field. Furthermore, the presence of oppositely charged surface heterogeneities on the microchannel walls results in the formation of localized flow circulation regions within the bulk flow. These circulation regions grow and decay periodically in accordance with the periodic variation of the AC electric field intensity and provide an effective means of enhancing species mixing in the microchannel. Consequently, the use of an AC electric field together with patchwise surface heterogeneities permits a significant reduction in both the mixing channel length and the retention time required to attain a homogeneous solution.

This study numerically investigated the influences of ventilation designs on pollutant removal in a large space with multiple pollutant sources. The types of ventilation include general displacement and local exhaust ventilation with either partitioned or non-partitioned working field. The study demonstrated that the outlet positions and outlet flow rate distribution for local exhaust ventilation are more important than those of the general displacement type. It would be more effective to design local exhaust by placing the outlets on the midstream and downstream of the machines rather than on all the machines. The results also demonstrated that the effect of local exhaust type would not be more superior to the general displacement type due to the large space in plant and multiple pollutant sources such as oil gas pollutant source, mist of metalworking fluid, etc.

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