It is known that the stark disparities between soft tissues and rigid electronics generally introduce difficulties toward seamless interfaces between the two realms. [4] Ultraflexible (opto)electronics and sensors, defined with a thickness down to 10 µm or below, have arisen as an important device configuration that presents extreme mechanical compliance and foresees remarkable application potentials toward imperceptible and wearable system. [5][6][7][8] Particularly for health monitoring applications, intimate contact between sensing components and the human skin would effectively reduce skin-contact impedance, minimize motion artifact, enhance measurement accuracy, and simplify subsequent data possessing algorithm. Despite the significant progress in reducing the device thickness and maintaining high electrical performance, documented thin-film devices have certain limitations: lack of sufficient gas permeability and relatively high Young's modulus compared to that of human tissue. Besides, commonly used flexible substrates for electronics, e.g., parylene, polyethylene terephthalate (PET), polyethylene naphthalate, polyimide, On-skin electronics that offer revolutionary capabilities in personalized diagnosis, therapeutics, and human-machine interfaces require seamless integration between the skin and electronics. A common question remains whether an ideal interface can be introduced to directly bridge thin-film electronics with the soft skin, allowing the skin to breathe freely and the skin-integrated electronics to function stably. Here, an ever-thinnest hydrogel is reported that is compliant to the glyphic lines and subtle minutiae on the skin without forming air gaps, produced by a facile cold-lamination method. The hydrogels exhibit high water-vapor permeability, allowing nearly unimpeded transepidermal water loss and free breathing of the skin underneath. Hydrogel-interfaced flexible (opto)electronics without causing skin irritation or accelerated device performance deterioration are demonstrated. The long-term applicability is recorded for over one week. With combined features of extreme mechanical compliance, high permeability, and biocompatibility, the ultrathin hydrogel interface promotes the general applicability of skin-integrated electronics.

BACKGROUND: Rhodosporidium toruloides can transform carbohydrates from lignocellulosic hydrolyzate into long-chain fatty acids that contribute to biodiesel production. However R. toruloides cannot survive in lignocellulosic hydrolyzate due to the inhibitory effects of the byproducts co-produced by hydrolysis.

Abstract-Caching and multicasting are two promising methods to support massive content delivery in multi-tier wireless networks. In this paper, we consider a random caching and multicasting scheme with caching distributions in the two tiers as design parameters, to achieve efficient content dissemination in a two-tier large-scale cache-enabled wireless multicasting network. First, we derive tractable expressions for the successful transmission probabilities in the general region as well as the high SNR and high user density region, respectively, utilizing tools from stochastic geometry. Then, for the case of a single operator for the two tiers, we formulate the optimal joint caching design problem to maximize the successful transmission probability in the asymptotic region, which is nonconvex in general. By using the block successive approximate optimization technique, we develop an iterative algorithm, which is shown to coverage to a stationary point. Next, for the case of two different operators, one for each tier, we formulate the competitive caching design game where each tier maximizes its successful transmission probability in the asymptotic region. We show that the game has a unique Nash equilibrium (NE) and develop an iterative algorithm, which is shown to converge to the NE under a mild condition. Finally, by numerical simulations, we show that the proposed designs achieve significant gains over existing schemes.

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