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A new halogenated 4,4-difluoro-4-bora-3a,4a-diazas- indacene (BODIPY) derivative was designed as a singlet-oxygen photosensitizer (PS) for use as a photodynamic therapy (PDT) agent, and its photophysical properties were characterized. The PS, having two iodine atom substituents, exhibited a low fluorescence quantum yield (ΦFL) of 0.02 and high singlet-oxygen-generation quantum yield (ΦΔ) of 0.93. Furthermore, in vitro photodynamic activities were evaluated to assess the potential of using the PS for PDT. A propidium iodide (PI) fluorescence assay and live-cell imaging of Lewis lung carcinoma (LLC) cells demonstrated that the cellular damage is induced by the photosensitization of the BODIPY dye, which subsequently leads to cell death by necrosis. [ABSTRACT FROM AUTHOR]

Biodegradable triboelectric nanogenerators (TENGs) have been studied for powering biotransient electronics in past years. For stable powering, developing biodegradable materials which have high tribopositive properties as well as high biocompatibility is crucially required. Here, we investigate a nature-derived ϰ-carrageenan-agar (ϰC-Agar) composite as high-performing triboelectric friction material for biodegradable TENG. We found that the composite shows greatly enhanced electron-donating property. At an optimized ϰC concentration of 80 wt%, the surface potential at most 57.5% increases compared to bare materials. We validated that the enhancement was caused by increased charge trapping sites consisting of Ca2+ cations and sulfate ester groups in the composite. In addition, we found that the ϰC-Agar composite has high intrinsic biocompatibility as it shows high cell viability in MTT assay and subdermal implant causes little noticeable inflammation, contributed by the high hydrophilicity of the composite. We further demonstrate a fully biodegradable TENG using an optimized ϰC-Agar composite. Very thin (0.3 mm) and flexible our device generates high output root-mean-square (RMS) current of 0.45 mA·m−2 and output RMS power of 0.15 mW·m−2 at optimized impedance. Our work provides a basis for the development of high-performance biodegradable TENGs for self-powered transient electronics. We investigate a nature-derived ϰ-carrageenan-agar (ϰC-Agar) composite as a highly performing tribopositive friction material for the biodegradable triboelectric nanogenerator (TENG). The composite exhibits significantly increased surface potential and it is originated from abundant charge trapping sites. Confirming high biocompatibility through MTT assay and histologic study, a fully biodegradable TENG based on the optimized ϰC-Agar composite is demonstrated. Our work provides a basis for the development of high-performance biodegradable TENGs for self-powered transient electronics. [Display omitted] • We investigate a ϰC-Agar composite as a biodegradable, highly tribopositive material for biomechanical energy harvesting. • High electron-donating property of the composite by the abundant charge trapping sites is verified. • High biocompatibility of the composite is verified through MTT assay and histologic study. • A fully biodegradable TENG generates high output RMS current/power of 0.45 mA·m−2/0.15 mW·m−2 despite of very thin airgap. [ABSTRACT FROM AUTHOR]

The transient response of a proton exchange membrane fuel cell (PEMFC) is an important issue for transportation applications. The objective of this study is to investigate the effects of operating and controlling parameters on the transient response of a PEMFC for achieving more stable cell performance under load change conditions. The transient response of a PEMFC was measured and analyzed by varying air stoichiometry, air humidity, and air excess ratio (AER). The optimal air stoichiometry and AER were determined to minimize the voltage drop, undershoot, and voltage fluctuation under the load change, while maintaining high cell performance. Based on the present data, the optimal air stoichiometry was determined to be between 2.0 and 2.5, and the optimal AER was suggested to be between 1.65 and 2.0. [ABSTRACT FROM AUTHOR]

Highlights: [•] Effect of cathode channel size on the air-blowing PEMFC is analyzed. [•] Performance and EIS tests of air-blowing PEMFCs are conducted. [•] Test conditions include the operating temperature, fan voltage, and anode humidity. [•] Flooding is a limiting factor for decreasing channel size at low temperature. [•] Water management is investigated by analyzing ohmic resistance. [Copyright &y& Elsevier]

In neural network models, obtaining a high-quality dataset is critical because they are generally reliant on training data. A common problem that occurs is class imbalance, in which models tend to be biased to the majority class when the training data is not balanced. To overcome this problem, we propose a novel regularization method that provides a penalty to the loss function, using two facets of the distribution of the model's output p (y ̂ | x) : (1) skewed mean and (2) variance divergence between p (y ̂ | x ∈ D +) and p (y ̂ | x ∈ D −). The experimental results demonstrate that our methods consistently improve the performance on imbalanced datasets. Moreover, the combination of two regularization methods provides a substantial performance improvement on five sentence classification datasets and also an image classification dataset; notably, state-of-the-art performances are achieved on the WikiQA and SelQA datasets. • Class imbalance problems cause performance decline by making the model skewed. • Regularization methods using the aspects of the output of the network are proposed. • Proposed methods can improve performance when the training data is not balanced. • The combination of proposed regularization methods can achieve further improvements. [ABSTRACT FROM AUTHOR]

Controlling the aggregation behaviorof organic dyes is importantfor understanding and exploring supramolecular assembly utilizingthe specific characteristics of aggregation. Regulating J-aggregationby electrostatic interactions between anionic polyelectrolytes andcationic dyes has gained growing interest. Here, we report the formationof J-aggregates of a water-soluble cationic squaraine dye, 4-(pyridinium-1-yl)butylbenzothiazoliumsquaraine (SQ), using poly(acrylic acid) sodium salt(PAA-Na) as a template. Electrostatic interactions between the PAA-Napolyelectrolyte and the cationic SQdye enhanced J-aggregation;the absorbance of the resulting J-band with the polyelectrolyte templatewas much sharper than the absorbance of the J-aggregate formed usinga high concentration of NaCl. Significantly, removal of the polyelectrolytePPA-Na template by the introduction of calcium ions, which can formstronger ionic binding with carboxylate groups, dissociated J-aggregates,freeing the SQmolecules back to unaggregated or loweraggregate forms. To demonstrate the reversibility of the J-aggregateformation cycle, an in situ experiment was conducted that showed 60%reversibility of the second cycle. In addition, an enhancement byca. 23 times per repeat unit of the two-photon absorption (2PA) crosssection was observed at 920 nm for the polyelectrolyte template-SQJ-aggregate compared to unaggregated or lower aggregate SQ. These results suggest a prominent role of polyelectrolytetemplated SQJ-aggregation in the enhancement of 2PAefficiency and provide a means of modulating supramolecular assembly. [ABSTRACT FROM AUTHOR]