We present a novel mechanism of particle manipulation in alternating-current (ac)-driven electro-osmotic micropumps, utilizing the tunable ratio of viscous drag, inertial and dielectrophoretic forces. The latter are induced by three-dimensional (3D) stepped electrode arrays in the channel, which are driven by ac voltages enabling so-called 3D-ac-electro-osmotic pumping, as has been proposed recently. Due to size-and density-dependent differences in polarizability, targeted particles in the fluid stream can be slowed down or even pinned above the electrode structures solely by adjusting the operation parameters of the pump. Hence the presented device, fabricated in SU-8/glass technology, enables simultaneous pumping and manipulation of particles in suspension.

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One of the biggest challenges of communication networks is the video transmission in real time. It requires high demands on the available network capacity and transport mechanisms. Availability of smart mobile devices with batteries, which keep the terminal working for several hours, caused an increased interest in the research of the deployment of video transmission in wireless transmission systems. The presented paper deals with the transmission of video encoded with H.264/AVC (Advanced Video Coding) video coding standard through wireless local area network (WLAN) using the programming environment OPNET Modeller (OM). The test network studied in this work was prepared by combining real and simulated networks, which allows interesting possibilities when working with the OM tools. Such an approach to working with OM allows a detailed video streaming analysis, because the video output was noticeably not only in the form of statistics, but we can see the real impact of transmission failures. Using the OM simulation environment allows to design the transmission systems, which would be difficult to establish in laboratory conditions.

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The formation of two-dimensional carrier gases in gated GaN/AlGaN/GaN heterostructures is investigated theoretically. It is shown that under certain conditions a two-dimensional hole gas at the upper GaN/AlGaN interface can be formed in addition to the two-dimensional electron gas at the lower AlGaN/GaN interface. For the calculations, a Schrdinger-Poisson solver and a simple analytical model developed in the present work are used. Conditions for the formation of a two-dimensional hole gas are elaborated. It is shown that once a two-dimensional hole gas is created, it shields the coexisting two-dimensional electron gas which will result in a diminishing effect of the gate voltage on the two-dimensional electron gas