Objective: Artifact subspace reconstruction (ASR) is an automatic, online-capable, component-based method that can effectively remove transient or large-amplitude artifacts contaminating ...electroencephalographic (EEG) data. However, the effectiveness of ASR and the optimal choice of its parameter have not been systematically evaluated and reported, especially on actual EEG data. Methods: This paper systematically evaluates ASR on 20 EEG recordings taken during simulated driving experiments. Independent component analysis (ICA) and an independent component classifier are applied to separate artifacts from brain signals to quantitatively assess the effectiveness of the ASR. Results: ASR removes more eye and muscle components than brain components. Even though some eye and muscle components retain after ASR cleaning, the power of their temporal activities is reduced. Study results also showed that ASR cleaning improved the quality of a subsequent ICA decomposition. Conclusions: Empirical results show that the optimal ASR parameter is between 20 and 30, balancing between removing non-brain signals and retaining brain activities. Significance: With an appropriate choice of parameter, ASR can be a powerful and automatic artifact removal approach for offline data analysis or online real-time EEG applications such as clinical monitoring and brain-computer interfaces.
Frequent subgraph mining is a core graph operation used in many domains, such as graph data management and knowledge exploration, bioinformatics, and security. Most existing techniques target static ...graphs. However, modern applications, such as social networks, utilize large evolving graphs. Mining these graphs using existing techniques is infeasible, due to the high computational cost. In this paper, we propose IncGM+, a fast incremental approach for continuous frequent subgraph mining on a single large evolving graph. We adapt the notion of "fringe" to the graph context, that is the set of subgraphs on the border between frequent and infrequent subgraphs. IncGM+ maintains fringe subgraphs and exploits them to prune the search space. To boost the efficiency, we propose an efficient index structure to maintain selected embeddings with minimal memory overhead. These embeddings are utilized to avoid redundant expensive subgraph isomorphism operations. Moreover, the proposed system supports batch updates. Using large real-world graphs, we experimentally verify that IncGM+ outperforms existing methods by up to three orders of magnitude, scales to much larger graphs and consumes less memory.
•PT-based CPs w/ tetraethylene glycol-bridged carbonyl ester side chains for OECTs.•P2-based OMIEC exhibits enhanced electronic/ion transport and film adhesion.•P2-based OMIEC reduces film swelling ...during electrochemical operation.•P2-based OMIEC exhibits significant protein repulsion properties against BSA.•Interdigitated P2-based OECT exhibits improved device performance and stability.
Organic mixed ionic-electronic conductors (OMIECs) hold great promise in the fields of bioelectronics, optoelectronics, and energy storage devices, and are characterized by unique microregions that facilitate electron and ion transport during electrochemical operations in electrolytes. In particular, conjugated polymers (CPs) can serve as interfaces for OMIECs to facilitate reversible reactions during electrochemically-driven ion implantation. In applications involving organic electrochemical transistors (OECTs), this mechanism greatly enhances the amplification of electrical signals, while the ion transport properties vary depending on the design of the polymer side chains. In this study, we strategically designed the side chains in the synthesis of polythiophene (PT)-based CPs and systematically investigated their effects on the electrochemical properties as well as the modulation of the charge entry and exit characteristics of the films. To gain insight into the material properties and stacking states of the poly(ethylene glycol) (PEG) side chains on the CP backbone, X-ray photoelectron spectroscopy (XPS) and theoretical calculations of the CP surface energy were performed. In addition, we evaluated their hydrophilicity and protein-repelling properties by wettability tests and electrochemical dissipative quartz crystal microbalance measurements, respectively. The films of P1 (with branched alkyl-bridged carbonyl ester side chains), P2 (with tetraethylene glycol-bridged carbonyl ester side chains), and P3 (with tetraethylene glycol side chains) have distinctly different ion/electron transport properties. Unlike P1 and P3, P2 reduced film swelling during electrochemical operation in an aqueous NaCl electrolyte and showed a greater ability to repel proteins, especially bovine serum albumin. Subsequently, we integrated these CP films into the comb-like active-layer channels of OECTs. Our results show that the P2 film improves the ion/electron transport properties and adhesion on the electrodes without affecting the carrier mobility (μ) and clearly exhibits fully reversible electrochromic behavior at low operating voltages (<1 V). Furthermore, P2 exhibits superior long-term stability during OECT operation compared to P3. Our findings establish material design principles for bridged carbonyl ester PEG side-chain PTs, which are essential for fine-tuning their suitability for biomedical applications in OECTs.
Crystallinity and crystal orientation have a predominant impact on a materials’ semiconducting properties, thus it is essential to manipulate the microstructure arrangements for desired ...semiconducting device performance. Here, ultra‐uniform hole‐transporting material (HTM) by self‐assembling COOH‐functionalized P3HT (P3HT‐COOH) is fabricated, on which near single crystal quality perovskite thin film can be grown. In particular, the self‐assembly approach facilitates the P3HT‐COOH molecules to form an ordered and homogeneous monolayer on top of the indium tin oxide (ITO) electrode facilitate the perovskite crystalline film growth with high quality and preferred orientations. After detailed spectroscopy and device characterizations, it is found that the carboxylic acid anchoring groups can down‐shift the work function and passivate the ITO surface, retarding the interface carrier recombination. As a result, the device made with the self‐assembled HTM show high open‐circuit voltage over 1.10 V and extend the lifetime over 4,300 h when storing at 30% relative humidity. Moreover, the cell works efficiently under much reduced light power, making it useful as power source under dim‐light conditions. The demonstration suggests a new facile way of fabricating monolayer HTM for high efficiency perovskite devices, as well as the interconnecting layer needed for tandem cell.
Self‐assembled P3HT‐COOH is an excellent hole extraction layer to fabricate robust, high‐performance, and extremely reproducible perovskite solar cells. The well‐aligned self‐assembled P3HT‐COOH generates a dipole layer between indium tin oxide and perovskite, substantially retarding interface charge recombination and producing highly sensitive devices to dim light. The enhanced crystallinity and preferred out‐of‐plane orientation play a key role to suppress the device degradation process.
MoS2 quantum dots (QDs)‐based white‐light‐emitting diodes (QD‐WLEDs) are designed, fabricated, and demonstrated. The highly luminescent, histidine‐doped MoS2 QDs synthesized by microwave induced ...fragmentation of 2D MoS2 nanoflakes possess a wide distribution of available electronic states as inferred from the pronounced excitation‐wavelength‐dependent emission properties. Notably, the histidine‐doped MoS2 QDs show a very strong emission intensity, which exceeds seven times of magnitude larger than that of pristine MoS2 QDs. The strongly enhanced emission is mainly attributed to nitrogen acceptor bound excitons and passivation of defects by histidine‐doping, which can enhance the radiative recombination drastically. The enabled electroluminescence (EL) spectra of the QD‐WLEDs with the main peak around 500 nm are found to be consistent with the photoluminescence spectra of the histidine‐doped MoS2 QDs. The enhanced intensity of EL spectra with the current increase shows the stability of histidine‐doped MoS2 based QD‐WLEDs. The typical EL spectrum of the novel QD‐WLEDs has a Commission Internationale de l'Eclairage chromaticity coordinate of (0.30, 0.36) exhibiting an intrinsic broadband white‐light emission. The unprecedented and low‐toxicity QD‐WLEDs based on a single light‐emitting material can serve as an excellent alternative for using transition metal dichalcogenides QDs as next generation optoelectronic devices.
A “single light‐emitting material,” “low‐toxicity,” and “economical fabrication process” white‐light‐emitting diode based on histidine‐doped MoS2 quantum dots is successfully designed, fabricated, and demonstrated. This work overcomes the low‐luminescence problem for traditional 2D transition metal dichalcogenides and achieves high performance white‐light‐emitting diodes with an intrinsic broadband white‐light electroluminescence and a Commission Internationale de l'Eclairage chromaticity coordinate of (0.30, 0.36).
Autotransplantation is a beneficial treatment with a high success rate for young patients. However, most adult patients require root canal treatment (RCT) of the donor teeth after the ...autotransplantation procedure, which causes a prolonged treatment time and additional expenses and increases the rate of future tooth fracture. Rapid prototyping (RP)-assisted autotransplantation shortens the extra-alveolar time and enables a superior clinical outcome. However, no cohort studies of the application of this method on adult populations have been reported.
This study is a retrospective cohort study. All patients underwent autotransplantation from 2012 to 2020 in the Kaohsiung and Chia-Yi branches of Chang Gung Memorial Hospital, and the procedure and clinical outcomes were analysed. Differences in clinical outcomes, age, sex, extra-alveolar time, fixation method, and RCT rate were compared between the two groups.
We enrolled 21 patients, 13 treated using the conventional method and 8 treated using the RP-based technique. The RCT rates of the conventional group and RP group were 92.3% and 59%, respectively. The mean age of the two groups was significantly different (28.8 ± 10 vs. 21.6 ± 2.1); after performing subgroup analysis by excluding all of the patients aged > 40 years, we found that the RCT rates were still significantly different (91.0% vs. 50%). The mean extra-alveolar time was 43 s in the RP group, and the autotransplantation survival rate in both groups was 100%.
Rapid prototyping-assisted autotransplantation was successfully adopted for all patients in our study population. By shortening the extra-alveolar time, only 50% of the patients required a root canal treatment with a 100% autotransplantation survival rate.
Retrospectively registered.
A self-assembled polar monolayer (SAPM) is proposed to serve as the hole-transport layer (HTL) in optoelectronic devices. To illustrate our working principle, a superior performance of ...organic-inorganic halide perovskite (OIHP) photodetectors and solar cells is reported. A monolayer of poly3-(6-carboxyhexyl)thiophene-2,5-diyl (P3HT-COOH) was prepared on an ITO anode through a self-assembled process as HTL. It was found that the self-assembled P3HT-COOH monolayer exhibited a preferential dipole orientation on the ITO and possessed an electric field pointing toward the ITO side, which produced a positive shift of lowest-dark-current-density bias and a reduced work function relative to the spin-coated film. The presence of this internal electric field in OIHP photodetectors facilitates charge collection and assists carrier transport. Additionally, the higher LUMO level of SAPM could effectively block electron injection and lower the dark current density in comparison with that made from spin-coated P3HT-COOH. As a result, an OIHP photodetector with SAPM as the HTL demonstrated a detectivity of more than 3.03 × 10
13
cm Hz
1/2
W
−1
, a response time of 95 ns, a responsivity of 0.479 AW
−1
, and a stable responsivity over 11 decades. Moreover, solar cells based on SAPM exhibit much better power conversion efficiency than conventional PEDOT:PSS-based devices. All these outstanding results can be extended to many other material systems, which ensure that our approach represents a key step toward the advancement in the development of cost-effective and high-performance semiconductor optoelectronic devices.
Perovskite photodetectors adopting a self-assembled polar hole-transport monolayer demonstrate a superior detectivity, responsivity, LDR values, and response time, which outperform previous reports.
Artifact Subspace Reconstruction (ASR) is a machine learning technique widely used to remove non-brain signals (referred to as "artifacts") from electroencephalograms (EEGs). The ASR algorithm can, ...however, be constrained by the limited memory available on portable devices. To address this challenge, we propose a Hardware-Oriented Memory-Limited Online ASR (HMO-ASR) algorithm. The proposed HMO-ASR algorithm consists of (1) two-level window-based preprocessing including PCA-based and z-score-based preprocessing to clean the data in each window, (2) iterative mean, standard deviation, and covariance update using a parallel algorithm to achieve window-based processing, and (3) early eigenvector matrix determination to save the computation. With the three schemes, the HMO-ASR method can be implemented on mobile devices, application-specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs) with limited memory. The study results showed that the proposed HMO-ASR algorithm can achieve comparable performance to those obtained by the offline ASR algorithm with a 98.64% reduction in memory size. An FPGA implementation is used for silicon proof of the proposed HMO-ASR algorithm.
One of the greatest challenges that hinder the decoding and application of electroencephalography (EEG) is that EEG recordings almost always contain artifacts - non-brain signals. Among existing ...automatic artifact-removal methods, artifact subspace reconstruction (ASR) is an online and real-time capable, component-based method that can effectively remove transient or large-amplitude artifacts. However, the effectiveness of ASR and the optimal choice of its parameter have not been evaluated and reported, especially on real EEG data. This study systematically validates ASR on ten EEG recordings in a simulated driving experiment. Independent component analysis (ICA) is applied to separate artifacts from brain signals to allow a quantitative assessment of ASR's effectiveness in removing various types of artifacts and preserving brain activities. Empirical results show that the optimal ASR parameter is between 10 and 100, which is small enough to remove activities from artifacts and eye-related components and large enough to retain signals from brain-related components. With the appropriate choice of the parameter, ASR can be a powerful and automatic artifact removal approach for offline data analysis or online real-time EEG applications such as clinical monitoring and brain-computer interfaces.
Chitosan (CS) shows in vitro and in vivo efficacy for siRNA delivery but with contradictory findings for incompletely characterized systems. For understanding which parameters produce effective ...delivery, a library of precisely characterized chitosans was produced at different degrees of deacetylation (DDAs) and average molecular weights (M n). Encapsulation and transfection efficiencies were characterized in vitro. Formulations were selected to examine the influence of M n and N:P ratio on nanoparticle uptake, metabolic activity, genotoxicity, and in vitro transfection. Hemocompatibility and in vivo biodistribution were then investigated for different M n, N:P ratios, and doses. Nanoparticle uptake and gene silencing correlated with increased surface charge, which was obtained at high DDA and high M n. A minimum polymer length of ∼60–70 monomers (∼10 kDa) was required for stability and knockdown. In vitro knockdown was equivalent to lipid control with no metabolic or genotoxicity. An inhibitory effect of serum on biological performance was dependent on DDA, M n, and N:P. In vivo biodistribution in mice show accumulation of nanoparticles in kidney with 40–50% functional knockdown.
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