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We simulated a pulsed direct current (DC) planar magnetron discharge using fluid model, solving for species continuity, momentum, and energy transfer equations, coupled with Poisson equation and Lorentz force for electromagnetism. Based on a validated DC magnetron model, an asymmetric bipolar potential waveform is applied at the cathode at 50-200 kHz frequency and 50-80% duty cycle. Our results show that pulsing leads to increased electron density and electron temperature, but decreased deposition rate over non-pulsed DC magnetron, trends consistent with those reported by experimental studies. Increasing pulse frequency increases electron temperature but reduces the electron density and deposition rate, whereas increasing duty cycle decreases both electron temperature and density but increases deposition rate. We found that the time-averaged electron density scales inversely with the frequency, and time-averaged discharge voltage magnitude scales with the duty cycle. Our results are readily applicable to modulated pulse power magnetron sputtering and can be extended to alternating current (AC) reactive sputtering processes.

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Ancylostoma ceylanicum is recognized as the only zoonotic hookworm species that is able to mature into adult stage in the human intestine. While human infections caused by this hookworm species have been reported from neighboring countries and this hookworm is prevalent in dogs in Vietnam, human infection has never been reported in Vietnam. The present study, therefore, aimed to identify human infections with A. ceylanicum in Vietnam. A total of 526 fecal samples from the residents in Long An Province were collected and the presence of hookworm eggs was detected by the Kato-Katz method. The results indicated that the overall prevalence of human hookworm infection was 85/526 (16.2%). After filter paper culture, 3rd stage larvae were successfully obtained from 48 egg-positive samples. The larvae were identified for their species using semi-nested PCR-RLFP on the cox1 gene. As a result, two hookworm species were confirmed; single species infections with Necator americanus or A. ceylanicum, and mixed infections with both species were found in 47.9%, 31.3%, and 20.8% of the samples, respectively.

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The hydrodynamic interaction between two nonspherical capsules suspended in a simple shear flow is studied numerically using a front-tracking method. The capsules are enclosed by thin shells which develop in-plane tensions and bending moments due to a preferred three-dimensional unstressed configuration. Computations are performed for capsules with spherical, oblate spheroidal, and biconcave unstressed shapes for a wide range of dimensionless shear rates and initial separation distances between the two capsules. The bending modulus and viscosity ratio between the internal and surrounding fluids are chosen to be those of healthy red blood cells. Depending on the initial separation distance, we find that two spherical capsules in shear flow either cross over each other or undergo spiraling motion. In addition, the long-time interaction behavior of capsules also depends strongly on the unstressed shapes. More oblate or biconcave capsules exhibit two additional type of interactions, namely swapping and continuous rotation, which occur only when each capsule undergoes tumbling motion.

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Using numerical simulations, we study the separation of deformable bodies, such as capsules, vesicles, and cells, in deterministic lateral displacement devices, also known as bump arrays. These arrays comprise regular rows of obstacles such as micropillars whose arrangements are shifted between adjacent rows by a fixed amount. We show that, in addition to the zigzag and laterally displaced trajectories that have been observed experimentally, there exists a third type of trajectory which we call dispersive, characterized by seemingly random bumpings off the micropillars. These dispersive trajectories are observed only for large and rigid particles whose diameters are approximately more than half the gap size between micropillars and whose stiffness exceeds approximately 500 MPa. We then map out the regions in phase space, spanned by the row shift, row separation, particle diameter, and particle deformability, in which the different types of trajectories are expected. We also show that, in this phase space, it is possible to transition from zigzag to dispersive trajectories, bypassing lateral displacement. Experimentally, this is undesirable because it limits the ability of the device to sort particles according to size. Finally, we discuss how our numerical simulations may be of use in device prototyping and optimization.

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Shear-induced deformation of liquid capsule enclosed by thin shell causes the development of in-plane tensions and bending moments due to the shell thickness or to a preferred three-dimensional unstressed configuration. This paper considers the effect of bending stiffness due to a preferred three-dimensional structure on the deformation and motion of the liquid capsule. To perform the numerical simulations, an improved formulation for computing the forces generated on the capsule surface during deformation is proposed. This formulation takes full account of large deformation kinematics and the development of in-plane tensions and bending moments. The deformation and orientation dynamics of capsules with different reference shapes are studied under various shear rates, viscosity ratios, and bending modulus. The numerical results show that the bending stiffness not only restricts the deformation but also affects the motion mode of the capsules. In addition, raising bending stiffness amplifies the shape deformation oscillations in tank-treading mode but reduces the oscillations in tumbling mode.

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We present a coupled immersed interface method-boundary element method (IIM-BEM) numerical technique that predicts the behaviour of deformable cells under the effect of both hydrodynamic and electrical forces. This technique is applied to the study of a hybrid electrical-mechanical trap for single-cell trapping. We report on the effect of different combinations of electrode positions and mechanical properties of the trap on the maximum loading and unloading Reynolds numbers. We also report on the effect that cells moving with the flow have on cells which have been already trapped in a cavity.

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