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  1. In recent years, there has been a growing interest in using tandem foils to mimic and study fish swimming, and to inform underwater vehicle design. Though much effort has been put to understanding the propulsion mechanisms of a tandem-foil system, the stability of such a system and the mechanisms for maintaining it remain an open question. In this study, a 3-foil system in an in-line configuration is used towards understanding the hydrodynamics of lateral stability. The foils actively pitch with varying phase. To quantify lateral force oscillation, the standard deviation of the lateral force, 𝝈𝝈𝒀𝒀, calculated over one typical flapping cycle is used, to account for the amount of variation in the lateral force experienced by the system of 3 foils. The higher the standard deviation, the more the spread in the lateral force cycle data, the more lateral momentum exchanged between the flow and the foils, and the less stable the system is. Through phase variations, it is found that the lateral force is minimized when the phases of the three foils are approximately, though not exactly, evenly distributed. The least stable system is found to be the one with the foils all in phase. Systems that are more laterally stable are found to tend to have narrower envelopes of regions around the foils with high momentum. Near-wake of the foils, the envelopes of stable systems are also found to have pronounced convergent sections, whereas the envelope of the less stable systems are found to diverge without much interruption. In the far wake, coherent, singular thrust jets, along with orderly 2-S vortices are found to form in the two best performing cases. In less stable cases, the thrust jets are found to be branched. Corresponding to the width of the high-momentum envelopes, lateral jets are found to exist in the gaps between neighboring foils, the strengths of which vary based on stability, with the lateral jets being more pronounced in the less stable cases (cases with high amount of lateral force oscillation). Peak lateral forces are found to coincide with moments of pressure gradient build-up across the foils. The pressure-driven flow near the trailing edge of the foils then creates trailing-edge vortices, and correspondingly, lateral gap flows. Moments of peak and plateau lateral force on an individual foil in the system are found to coincide with the initiation and shedding of trailing-edge vortices, respectively. The formation of trailing-edge vortices, lateral jets and cross-stream flows in gaps are closely intertwined, and all are 1. Indicative of large lateral momentum oscillation, and 2. The results of pressure gradient build-up across foils. 
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    Free, publicly-accessible full text available January 19, 2024
  2. Free, publicly-accessible full text available May 5, 2024
  3. Free, publicly-accessible full text available January 1, 2024
  4. Recent technology development of logic devices based on 2-D semiconductors such as MoS2, WS2, and WSe2 has triggered great excitement, paving the way to practical applications. Making low-resistance p-type contacts to 2-D semiconductors remains a critical challenge. The key to addressing this challenge is to find high-work function metallic materials which also introduce minimal metal-induced gap states (MIGSs) at the metal/semiconductor interface. In this work, we perform a systematic computational screening of novel metallic materials and their heterojunctions with monolayer WSe2 based on ab initio density functional theory and quantum device simulations. Two contact strategies, van der Waals (vdW) metallic contact and bulk semimetallic contact, are identified as promising solutions to achieving Schottky-barrier-free and low-contact-resistance p-type contacts for WSe2 p-type field-effect transistor (pFETs). Good candidates of p-type contact materials are found based on our screening criteria, including 1H-NbS2, 1H-TaS2, and 1T-TiS2 in the vdW metal category, as well as Co3Sn2S2 and TaP in the bulk semimetal category. Simulations of these new p-type contact materials suggest reduced MIGS, less Fermi-level pinning effect, negligible Schottky barrier height and small contact resistance (down to 20 Ωμm ) 
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    Free, publicly-accessible full text available January 1, 2024
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  6. Free, publicly-accessible full text available August 1, 2024
  7. A new species, Gamasodes pachysetis Yao & Jin sp. nov., is described based on deutonymphs and adults from Jiangsu and Taiwan provinces, China. A nominal species, Gamasodes spiniger Trägårdh, 1910, new to China, is redescribed also based on deutonymph and adults from Guizhou Province. A key to Gamasodes species of China is presented. 
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  8. Lee, G.M. ; Kildegaard, H. Faustrup ; Lee, S.Y. (Ed.)
    Host cell protein (HCP) impurities, endogenous proteins expressed from host cells, can challenge biopharmaceutical manufacturing. Certain HCPs can persist even after downstream purification, leading to adverse impacts on drug stability and potentially, patient safety. Thus, the quantification and control of HCPs is critical. Although many improvements have been made in HCP quantification and control methods, HCP-associated risks cannot be completely eliminated. A better biophysical understanding of Chinese hamster ovary (CHO) HCPs and advancement of monitoring assays will lead to better controlled biopharmaceutical manufacturing. This chapter will discuss (i) current HCP removal processes for various product types, (ii) the impact of residual HCPs on drug efficacy and safety, (iii) HCP quantification and monitoring methods such as proteomics approaches and enzyme-linked immunosorbent assays (ELISA) using anti-HCP antiserum, (iv) HCP control approaches in both upstream and downstream processes, and (v) future directions for effective HCP risk management strategies. 
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  9. We study a heterogeneous two-tier wireless sensor network in which N heterogeneous access points (APs) collect sensing data from densely distributed sensors and then forward the data to M heterogeneous fusion centers (FCs). This heterogeneous node deployment problem is modeled as a quantization problem with distortion defined as the total power consumption of the network. The necessary conditions of the optimal AP and FC node deployment are explored in this paper. We provide a variation of Voronoi diagrams as the optimal cell partition for this network, and show that each AP should be placed between its connected FC and the geometric center of its cell partition. In addition, we propose a heterogeneous two-tier Lloyd-like algorithm to optimize the node deployment. Simulation results show that our proposed algorithm outperforms the existing methods like Minimum Energy Routing, Agglomerative Clustering, and Divisive Clustering, on average. 
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