Long nanopore reads are advantageous in de novo genome assembly. However, nanopore reads usually have broad error distribution and high-error-rate subsequences. Existing error correction tools cannot ...correct nanopore reads efficiently and effectively. Most methods trim high-error-rate subsequences during error correction, which reduces both the length of the reads and contiguity of the final assembly. Here, we develop an error correction, and de novo assembly tool designed to overcome complex errors in nanopore reads. We propose an adaptive read selection and two-step progressive method to quickly correct nanopore reads to high accuracy. We introduce a two-stage assembler to utilize the full length of nanopore reads. Our tool achieves superior performance in both error correction and de novo assembling nanopore reads. It requires only 8122 hours to assemble a 35X coverage human genome and achieves a 2.47-fold improvement in NG50. Furthermore, our assembly of the human WERI cell line shows an NG50 of 22 Mbp. The high-quality assembly of nanopore reads can significantly reduce false positives in structure variation detection.
Electrochemical synthesis of hydrogen peroxide (H2O2) through 2e– oxygen reduction reaction is an effective approach to replace anthraquinone process. However, most reported electrocatalysts work ...effectively in alkaline medium in which H2O2 will easily decompose into water. It is still of great challenge to develop cost‐effective electrocatalysts with high activity and selectivity for electrocatalytic H2O2 production in acidic media. Herein, it is first theoretically demonstrated that the adsorption energy of OOH* intermediate on carbon can be optimized by embedding Co nanoparticles (Co NPs) and tuning oxygen‐containing functional groups, ensuring high activity and selectivity. Guided by density functional theory calculations, highly porous open carbon nanocages with embedded Co NPs are designed and synthesized by template‐engaged method. The pyrolysis temperature can effectively modulate the electronic and pore structure of carbon nanocages. Impressively, the optimized carbon nanocages synthesized at 700 °C (P‐Co@C‐700) with highest percentage of –C–O–C group and defects, largest specific surface area (1351 m2 g–1), and mesoporous structure exhibit high selectivity up to 94% toward H2O2 production in 0.1 m HClO4. Furthermore, the P‐Co@C‐700 nanocages display promising application for efficient electro‐Fenton degradation of model organic pollutant.
The density functional theory calculations predict that the adsorption energy of OOH* on carbon can be optimized by embedding Co nanoparticles and tuning oxygen‐containing functional groups for the electrosynthesis of H2O2. Guided by calculations, open carbon nanocages with optimized electronic and pore structures are synthesized, manifesting high selectivity up to 94% for H2O2 synthesis in 0.1 m HClO4.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Many-objective optimization has posed a great challenge to the classical Pareto dominance-based multiobjective evolutionary algorithms (MOEAs). In this paper, an evolutionary algorithm based on a new ...dominance relation is proposed for many-objective optimization. The proposed evolutionary algorithm aims to enhance the convergence of the recently suggested nondominated sorting genetic algorithm III by exploiting the fitness evaluation scheme in the MOEA based on decomposition, but still inherit the strength of the former in diversity maintenance. In the proposed algorithm, the nondominated sorting scheme based on the introduced new dominance relation is employed to rank solutions in the environmental selection phase, ensuring both convergence and diversity. The proposed algorithm is evaluated on a number of well-known benchmark problems having 3-15 objectives and compared against eight state-of-the-art algorithms. The extensive experimental results show that the proposed algorithm can work well on almost all the test functions considered in this paper, and it is compared favorably with the other many-objective optimizers. Additionally, a parametric study is provided to investigate the influence of a key parameter in the proposed algorithm.
Molybdenum disulfide (MoS2) has received considerable interest for electrochemical energy storage and conversion. In this work, we have designed and synthesized a unique hybrid hollow structure by ...growing ultrathin MoS2 nanosheets on N‐doped carbon shells (denoted as C@MoS2 nanoboxes). The N‐doped carbon shells can greatly improve the conductivity of the hybrid structure and effectively prevent the aggregation of MoS2 nanosheets. The ultrathin MoS2 nanosheets could provide more active sites for electrochemical reactions. When evaluated as an anode material for lithium‐ion batteries, these C@MoS2 nanoboxes show high specific capacity of around 1000 mAh g−1, excellent cycling stability up to 200 cycles, and superior rate performance. Moreover, they also show enhanced electrocatalytic activity for the electrochemical hydrogen evolution.
Nanosheets‐on‐Box: A hybrid structure composed of thin MoS2 nanosheets supported on N‐doped carbon nanoboxes has been synthesized. Because of the structural advantages, these well‐defined C@MoS2 nanoboxes exhibit superior electrochemical performance as electrode materials for both lithium‐ion batteries and the hydrogen evolution reaction.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
As an emerging research topic, online class imbalance learning often combines the challenges of both class imbalance and concept drift. It deals with data streams having very skewed class ...distributions, where concept drift may occur. It has recently received increased research attention; however, very little work addresses the combined problem where both class imbalance and concept drift coexist. As the first systematic study of handling concept drift in class-imbalanced data streams, this paper first provides a comprehensive review of current research progress in this field, including current research focuses and open challenges. Then, an in-depth experimental study is performed, with the goal of understanding how to best overcome concept drift in online learning with class imbalance.
To facilitate software testing, and save testing costs, a wide range of machine learning methods have been studied to predict defects in software modules. Unfortunately, the imbalanced nature of this ...type of data increases the learning difficulty of such a task. Class imbalance learning specializes in tackling classification problems with imbalanced distributions, which could be helpful for defect prediction, but has not been investigated in depth so far. In this paper, we study the issue of if and how class imbalance learning methods can benefit software defect prediction with the aim of finding better solutions. We investigate different types of class imbalance learning methods, including resampling techniques, threshold moving, and ensemble algorithms. Among those methods we studied, AdaBoost.NC shows the best overall performance in terms of the measures including balance, G-mean, and Area Under the Curve (AUC). To further improve the performance of the algorithm, and facilitate its use in software defect prediction, we propose a dynamic version of AdaBoost.NC, which adjusts its parameter automatically during training. Without the need to pre-define any parameters, it is shown to be more effective and efficient than the original AdaBoost.NC.
Aggregation induced-emission (AIE) and antenna effects are important luminescence behaviors. Thus, investigating their emission mechanisms and revealing their behaviors have become critical but ...challenging. Here we design and prepare metal–organic frameworks (MOFs) with an AIE ligand (i.e., tetrakis(4-carboxyphenyl)pyrazine (L1)) and Ln3+ ions (including Eu3+, Tb3+, and Gd3+). The emission from L1 is gradually enhanced during the formation of the MOFs because coordination restricts the intramolecular rotation. Thus, the emission is called as coordination-induced emission (CIE) with the same restriction of intramolecular rotation mechanism as AIE. Meanwhile, benzene rings twist to adapt to the MOFs’ rigid structure, so the emission blueshifts gradually, as an additional evidence of CIE. Both AIE and CIE are “rotation-restricted emission (RRE)”. Eu3+ ions exhibit the strongest emission with gradually enhanced intensity during the formation of L1-Eu MOF. Combined with emission properties from Tb3+ and Gd3+ ions, the antenna effect is verified. We also validate the conditions for the efficient sensitization of Ln3+ ions experimentally and refresh the threshold value of the energy gap between triplet state of a ligand and excited state of Ln3+ ions to 3000 cm–1. Thus, RRE and antenna effects are revealed and validated simultaneously. Because CIE of L1 and antenna effect emission from Eu3+ ions are enhanced simultaneously as strong dual emissions, ratiometric fluorescence detection is realized with the detection of arginine as a model. Our results incorporate AIE and CIE into RRE, which provides explicit information for the construction and application of emission systems with AIE ligands as building blocks. MOFs are also extended to explore the emission mechanism and the energy transfer between ligands and metal ions.
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IJS, KILJ, NUK, PNG, UL, UM
Achieving the activation of drugs within cellular systems may provide targeted therapies. Here we construct a tumour-selective cascade activatable self-detained system (TCASS) and incorporate imaging ...probes and therapeutics. We show in different mouse models that the TCASS system accumulates in solid tumours. The molecules show enhanced accumulation in tumour regions via the effect of recognition induced self-assembly. Analysis of the molecular penetration in tumour tissue shows that in vivo self-assembly increases the penetration capability compared to typical soft or hard nanomaterials. Importantly, the in vivo self-assembled molecules exhibit a comparable clearance pathway to that of small molecules, which are excreted from organs of the reticuloendothelial system (liver and kidney), while are relatively slowly eliminated from tumour tissues. Finally, this system, combined with the NIR probe, shows high specificity and sensitivity for detecting bladder cancer in isolated intact patient bladders.
Developing efficient oxygen evolution reaction (OER) electrocatalysts for seawater electrolysis is still a big challenge. Herein, a facile one‐pot approach is reported to synthesize RuO2‐incorporated ...NiFe‐metal organic framework (RuO2/NiFe‐MOF) with unique nanobrick‐nanosheet heterostructure as precatalyst. Driven by electric field, the RuO2/NiFe‐MOF dynamically reconstructs into RuO2 nanoparticles‐anchored NiFe oxy/hydroxide nanosheets (RuO2/NiFeOOH) with coherent interface, during which the dissolution and redeposition of RuO2 are witnessed. Owing to the synergistic interaction between RuO2 and NiFeOOH, the as‐reconstructed RuO2/NiFeOOH exhibits outstanding alkaline OER activity with an ultralow overpotential of 187.6 mV at 10 mA cm−2 and a small Tafel slope of 31.9 mV dec−1 and excellent durability at high current densities of 840 and 1040 mA cm−2 in 1 m potassium hydroxide (KOH). When evaluated for seawater oxidation, the RuO2/NiFeOOH only needs a low overpotential of 326.2 mV to achieve 500 mA cm−2 and can continuously catalyze OER at 500 mA cm−2 for 100 h with negligible activity degradation. Density function theory calculations reveal that the presence of strong interaction and enhanced charge transfer along the coherent interface between RuO2 and NiFeOOH ensures improved OER activity and stability.
RuO2 nanoparticles‐anchored NiFe oxy/hydroxide nanosheets (RuO2/NiFeOOH) with coherent interface are dynamically reconstructed from unique nanobrick‐nanosheet heterostructured RuO2/NiFe‐metal organic framework. The as‐reconstructed RuO2/NiFeOOH exhibits outstanding oxygen evolution reaction (OER) activity and stability for seawater oxidation. Density function theory calculations reveal that strong interaction and enhanced charge transfer along the coherent interface between RuO2 and NiFeOOH ensure improved OER activity and stability.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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