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Lightweight, electrically insulating and high thermally conductive materials are highly desirable in electronic and power systems because they can effectively transfer heat and avoid temperature rise of the equipment and devices, thus guaranteeing normal operation. In this work, silica-coated spherical boron nitride (SiO2@s-BN) was successfully fabricated and prepared as a thermally conductive composite by blending with silicone rubber (SR). Due to the modulus matching, SiO2@BN could decrease the thermal resistance between the SR matrices and the thermally conductive fillers, thus achieving higher thermal conductivity compared with the original BN at the same filler loading. When the SR composite is filled with 40 wt% SiO2@BN, the thermal conductivity can reach 1.2 W m−1 K−1, which is 16.5% higher than that of the 40 wt% s-BN/SR composite. Simultaneously, the 40 wt% SiO2@BN/SR composite material not only exhibits excellent dielectric, thermal, and mechanical properties but also demonstrates outstanding processability, maintaining a low precursor viscosity of only 14.5 Pa·s. Overall, this work provides a novel strategy for developing high thermally conductive SR composites with good processability. [ABSTRACT FROM AUTHOR]

Hydrogenation–Disproportionation–Desorption–Recombination (HDDR) Nd2Fe14B particles have excellent magnetic properties, but the magnetic properties of powder are not uniform across different particle sizes. The remanence and maximum magnetic energy products of samples with a particle size of 120 μm are 14.0 kGs and 41.35 MGOe, while the products of samples with a particle size of 60 μm are only 13.3 kGs and 36.31 MGOe. The macroscopic morphology of HDDR Nd2Fe14B particles and the gradient distribution of microstructures in different micro-regions were observed. By modifying the macroscopic morphology of the particles, the poorly oriented clusters on the surface of the particles were precisely eliminated, and the remanence and maximum magnetic energy products of the particles increased to 14.5 kGs and 45 MGOe, respectively. Compared with the original particles, the samples after mechanical grinding had better grain arrangement. The effects of the nanocrystalline c-axis and field misalignment angle θ on the magnetic properties of HDDR Nd2Fe14B particles were investigated through micromagnetic simulation. The targeted removal of macroscopic defects on the particle surface contributed to a 3.6% increase in remanence and an 8.8% increase in the maximum magnetic energy product, offering a promising approach to enhance the microstructure of high-performance HDDR Nd2Fe14B particles. [ABSTRACT FROM AUTHOR]

Due to the lack of a method to efficiently represent the multimodal information of a protein, including its structure and sequence information, predicting compound-protein binding affinity (CPA) still suffers from low accuracy when applying machine-learning methods. To overcome this limitation, in a novel end-to-end architecture (named FeatNN), we develop a coevolutionary strategy to jointly represent the structure and sequence features of proteins and ultimately optimize the mathematical models for predicting CPA. Furthermore, from the perspective of data-driven approach, we proposed a rational method that can utilize both high- and low-quality databases to optimize the accuracy and generalization ability of FeatNN in CPA prediction tasks. Notably, we visually interpret the feature interaction process between sequence and structure in the rationally designed architecture. As a result, FeatNN considerably outperforms the state-of-the-art (SOTA) baseline in virtual drug evaluation tasks, indicating the feasibility of this approach for practical use. FeatNN provides an outstanding method for higher CPA prediction accuracy and better generalization ability by efficiently representing multimodal information of proteins via a coevolutionary strategy. [ABSTRACT FROM AUTHOR]

Forward-looking multi-channel synthetic aperture radar (FLMC-SAR) can realize two-dimension image formation in monostatic mode. This system must face the problem of left–right Doppler ambiguity. In the traditional methods, the spatial degrees of freedom of the FLMC-SAR system is expected to achieve Doppler ambiguity resolving by beamforming approaches. However, the influence of array error on beamforming cannot be ignored. In practice, the array error will lead to the mismatch of the space–time characteristic, which will reduce the performance of the Doppler ambiguity resolving method based on beamforming. This paper proposes a sparsity-based joint array calibration and ambiguity resolving method to enhance the robustness of FLMC-SAR imagery. For the FLMC-SAR system, the space–time characteristic of targets is first analyzed, based on which the observation model of FLMC-SAR Doppler ambiguity combined with array error is derived. Then, the Doppler ambiguity resolving and array error estimation are transformed into a sparse recovery problem. A modified quasi-Newton method is proposed to realize the array error estimation and Doppler ambiguity resolving of all targets in the local area. Finally, the results of the simulation and the real-data experiments verify that the proposed method can achieve FLMC-SAR Doppler ambiguity resolving and imaging. [ABSTRACT FROM AUTHOR]

Circularly polarized organic light-emitting diodes (CP-OLEDs) that demonstrate both state-of-the-art efficiency and strongly circularly polarized (CP) electroluminescence have proved a considerable technical challenge. Furthermore, multiple factors – from film thickness to device structure – have been shown to influence the sign of the emitted CP light, independent of the handedness (absolute stereochemistry) of the chiral emitter. Here we report CP-OLEDs using a blend of poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2) and a chiral small molecule additive (1-aza[6]helicene, aza[6]H). We demonstrate CP-OLEDs with an impressive electroluminescence dissymmetry (gEL) > 0.3 and a current efficiency of 0.53 cd A−1 and brightness of 3023 cd m−2. While at low aza[6]H loadings, F8T2 blends are consistent with previous observations of CP dissymetric inversion as a function of film thickness/excitation mode, a higher loading of aza[6]H (∼40 wt%) removes such dependencies while retaining excellent g-factors. The materials disclosed will allow for further mechanistic studies of chiral polymeric materials and provide new opportunities for chiroptical optimisation in films and devices. [ABSTRACT FROM AUTHOR]

Mitochondria, key organelles which keep in tune with energy demands for eukaryotic cells, are firmly associated with neurological conditions and post-traumatic rehabilitation. In vivo fluorescence imaging of mitochondria, especially with deep tissue penetration, would open a window to investigate the actual context of the brain. However, the depth of traditional two-photon mitochondrial fluorescence imaging is still limited due to the poor biological compatibility or low two-photon absorption cross-sections. A biocompatible mitochondria-targeted two-photon fluorescent dye (FO2) with an excellent two-photon absorption cross-section (the maximum of 1184 GM at 790 nm) and low cellular toxicity was designed and synthesized to overcome this problem. With this dye, we reached an imaging depth of ca. 640 μm during mitochondrial imaging of cortical cells in live animals. FO2 could be an excellent mitochondrial probe for live animal neural imaging to investigate the function and dysfunction of mitochondria in the brain. [ABSTRACT FROM AUTHOR]

Exciton behavior is crucial for improving the optoelectronic property of a light‐emitting conjugated polymer. Herein, the photoexcitation dynamics of exciton migration and energy transfer in a self‐doped β‐conformation film of the polydiarylfluorenes (poly[4‐(octyloxy)‐9,9‐diphenylfluoren‐2,7‐diyl]‐co‐[5‐(octyloxy)‐9,9‐ diphenylfluoren‐2,7‐diyl], PODPF) are demonstrated. Compared to the first generation of the β‐conformation polyfluorene, poly(9,9‐dioctylfluorene) (PFO), energy transfer occurs in PODPF β‐conformation films in a time period of ≈150 ps, much longer than those of the PFO ones (<5 ps), associated with the effective intrachain energy transfer (few hundred picoseconds), rather than interchain Förster energy transfer (a few picoseconds). Similar to PFO, the PODPF β‐conformation also displays well‐resolved vibronic emission peaks at 20 K, attributed to the planar and rigid conformation. Interestingly, a residual 0‐0 band emission of nonplanar conformation chain segments (435 nm, 2.85 eV) at 20 K also further confirms the exciton migration from the amorphous state to the β‐conformation domain in PODPF films. Therefore, the stable dual amplified spontaneous emission (ASE) behavior of the PODPF self‐doped films at 461 nm (2.69 eV) and 483 nm (2.57 eV), originates from the individual amorphous and β‐conformation domains. [ABSTRACT FROM AUTHOR]

We report on solution processed, highly light sensitive thin film transistors (TFTs) based on poly(9,9-dioctylfluorene-co-bithiophene) (F8T2). Transistors without heat treatment showed the highest saturation mobility, while devices annealed at 280 °C showed the highest drain current. The latter annealed transistors were found to give highly stable and reproducible performance over many light cycles. Measurements were carried out using an inorganic light emitting diode (LED) light source with a peak wavelength of 465 nm and 19 nm bandwidth from 0 to 400 μW/cm2 light intensity on TFTs with an F8T2 film thickness of 30 nm. The TFT OFF current was found to increase both with light intensity and gate bias. The bulk photogenerated carrier density was calculated to change from 5×1011 to 1×1013 cm-3 over the measured light intensity range. The TFT saturation mobility did not change with light intensity, remaining constant at 1.2×10-4 cm2/V s. The TFT ON current instead increased due to a shift in the turn-on voltage VT. This changed from -27 to -20 V over the measured light intensity range, initially changing rapidly but then saturating at higher intensity values. Contact resistance RC measurements showed large values in the dark. RC rapidly decreases with increasing light intensity, again saturating at higher values. From these results, we propose a phototransistor model in which illumination varies the device performance by effecting injection. By considering this shift in RC as photoassisted barrier lowering which additionally varies the width of the region depleted of carriers between the injecting interface and the channel, it is possible to explain the observed shift in VT as a change in the fraction of the gate bias dropped across the contact capacitance CC. By operating the phototransistor at a value of Vg=-5 V (below VT), it was possible to achieve a highly linear response of the photocurrent with light intensity. Alternatively, by operating at a value of Vg=-40 V (above VT), it was possible to maximize the photoresponsivity within the measured range. A photoresponsivity of 18.5 A/W at 5 μW/cm2 light intensity was achieved. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and characterization of copper (I) selenocyanate (CuSeCN) and its application as a solution‐processable hole‐transport layer (HTL) material in transistors, organic light‐emitting diodes, and solar cells are reported. Density‐functional theory calculations combined with X‐ray photoelectron spectroscopy are used to elucidate the electronic band structure, density of states, and microstructure of CuSeCN. Solution‐processed layers are found to be nanocrystalline and optically transparent (>94%), due to the large bandgap of ≥3.1 eV, with a valence band maximum located at −5.1 eV. Hole‐transport analysis performed using field‐effect measurements confirms the p‐type character of CuSeCN yielding a hole mobility of 0.002 cm2 V−1 s−1. When CuSeCN is incorporated as the HTL material in organic light‐emitting diodes and organic solar cells, the resulting devices exhibit comparable or improved performance to control devices based on commercially available poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate as the HTL. This is the first report on the semiconducting character of CuSeCN and it highlights the tremendous potential for further developments in the area of metal pseudohalides. [ABSTRACT FROM AUTHOR]

ABSTRACT We investigate the influence of particle plasmons on exciton and charge generation and recombination processes in the blend of poly (9-(1-octylnonyl)-9H-carbazole-benzothiadiazole-4,7-diyl-2,5-thiophenediyl) (PCDTBT) and [6,6]-phenyl-C70butyric acid methyl ester (PC70BM). The particle plasmons are generated from gold nanoparticles, which are embedded into PCDTBT:PC70BM blend. For the blend with gold nanoparticles, we observe enhance light harvesting. Despite the enhanced light collection, we find that the quasi-steady-state charge generation has not been influenced by the particle plasmons. However, the generation and recombination of long-lived (sub-millisecond) polaron paris have been significantly enhanced: from untrapped state in the pristine blend to the trapped state in the gold nanoparticle-embedded blend. This result implies that the plasmon-influenced polarons are trapped at the broadband geminate polaron pair (GPP) state. This state acts as an intermediate state, which either leads to the formation of charge transfer excitons (CTXs) or free charge carriers. In our case, the particle plasmon-influenced polarons are trapped in the GPP state, which leads to the formation of CTXs. For this reason, we do not observe the enhanced charge generation in PCDTBT:PC70BM blend with particle plasmon resonance. Finally, we revealed that the long-lived polarons mainly resulted from the localization by particle plasmons. The macroscopic modification in the blend film made negligible contributions to this influence. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 940-947 [ABSTRACT FROM AUTHOR]

The unique electronic structures of heteroatomic conjugated polymers (HCPs) offer an attractive platform to tune optoelectronic properties via a supramolecular coordination strategy. This study reports on an sp2 nitrogen heteroatom containing fluorene-based copolymer namely poly(9,9-dioctylfluorene- co-9,9-dioctyldiazafluoren-2,7-yl) (PF8- co-DAF8), with ≈20% DAF8 units. Tuning the optoelectronic properties of PF8- co-DAF8 via supramolecular coordination with a Lewis acid (B(C6F5)3 or AlCl3) is explored. Formation of either the PF8- co-DAF8-B(C6F5)3 or PF8- co-DAF8-AlCl3 adducts reduces the optical gap and causes an attendant redshift of the photoluminescence spectra. Controlling the degree and strength of the coordination allows the emission color to be tuned from blue through to green and yellow. This strategy is successfully implemented for polymer light-emitting diodes, confirming the large degree of spectral tuning whilst maintaining good device performance. Maximum luminous efficiencies, η ≈ 1.55 cd A−1@ 2120 cd m−2, 1.32 cd A−1@ 1424 cd m−2, and 2.56 cd A−1@ 910 cd m−2 are, respectively, recorded for the blue-emitting diodes with Commission Internationale de L'Eclairage (CIE) (x, y) coordinates = (0.16, 0.16), the white-emitting diodes with CIE (x, y) = (0.28, 0.38) and the green-emitting diodes with CIE (x, y) = (0.33, 0.52). The results highlight the versatility of the supramolecular coordination strategy in modifying the electronic structure of HCPs. [ABSTRACT FROM AUTHOR]

Wang, X.; Fang, D.; Wan, S., and Cheng, Y., 2019. Intelligent noise elimination algorithm for marine communication based on cluster collaboration In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 753–761. Coconut Creek (Florida), ISSN 0749-0208. In order to overcome the large amount of noise in marine communication and further improve the quality of communication under low SNR, an intelligent noise elimination algorithm based on cluster cooperation is proposed. Firstly, a finite perception congestion model is established, and a noise control strategy based on denoising operator for consistency algorithm is proposed. It is pointed out that when ε (t) is a high order infinite, the consistency algorithm after denoising can control the noise, make the Agent to converge to the original convergence state, and make the center to distribute normally. By frequency modulation, the noisy signal in communication is modulated into the instantaneous frequency of the analytic signal. In view of the non-linear characteristics of the marine communication signal, the cluster collaboration algorithm is realized by using the windowed Wigner-Ville distribution. For the high noise situation, the iterative algorithm can be used until the noise is completely eliminated. Experiments show that the algorithm can effectively eliminate communication noise and has high real-time performance. [ABSTRACT FROM AUTHOR]