摘要 : Background: Detecting DNA-binding proteins (DBPs) based on biological and chemical methods is time-consuming and expensive. Objective: In recent years, the rise of computational biology methods based on Machine Learning (ML) has greatly improved the detection efficiency of DBPs. Methods: In this study, the Multiple Kernel-based Fuzzy SVM Model with Support Vector Data Description (MK-FSVM-SVDD) is proposed to predict DBPs. Firstly, sex features are extracted from the protein sequence. Secondly, multiple kernels are constructed via these sequence features. Then, multiple kernels are integrated by Centered Kernel Alignment-based Multiple Kernel Learning (CKA-MKL). Next, fuzzy membership scores of training samples are calculated with Support Vector Data Description (SVDD). FSVM is trained and employed to detect new DBPs. Results: Our model is evaluated on several benchmark datasets. Compared with other methods, MKFSVM- SVDD achieves best Matthew's Correlation Coefficient (MCC) on PDB186 (0.7250) and PDB2272 (0.5476). Conclusion: We can conclude that MK-FSVM-SVDD is more suitable than common SVM, as the classifier for DNA-binding proteins identification.

摘要 : A biosensor was fabricated using graphene nano-sheets (GNSs) as the component for signal amplification and cetyltrimethylammonium bromide (CTAB) as the discriminating agent with the aim of achieving the selective and sensitive determination of dopamine (DA) in the presence of ascorbic acid (AA). The electrochemical behavior of DA was studied by cyclic voltammetry and differential pulse voltammetry (DPV). The results showed that DA and AA in coexisting solutions can be simultaneously oxidized in an electrochemical manner at significantly different potentials in the presence of CTAB. Therefore, DA can be selectively determined from a mixed solution even in the presence of interferents. The DPV current showed a linear dependence on DA concentrations ranging from 4 × 10−6 M to 5.2 × 10−5 M with a detection limit of 6.0 × 10−7 M. The proposed method was used to detect DA in real human blood serum using the standard addition method with satisfactory results. The reliability of the method was also examined with the fluorescence spectroscopy. The reaction mechanism was explored and a defect in micelles was highlighted to explain the high sensitivity and selectivity of the method.

摘要 : AbstractIncreasing the number of active sites is critical for developing N-doped carbon electrocatalysts towards oxygen reduction reaction (ORR) in fuel cells and metal-air batteries applications. Herein, we prepared N-doped carbon nanotubes (N-CNT) with enriched pyridinic N and abundant defects resulted from the etching of KMnO4 of the precursor (polypyrrole). It was observed that the content of pyridinic N could be well controlled by regulating the etching time. The resultant catalyst displayed a superior ORR activity compared commercial Pt/C in an alkaline solution, which was further confirmed by home-made Zn-air batteries. Density functional theory (DFT) computations showed that the superior catalytic activity originated from the second nearest carbon atom to the pyridinic-N at the edge. This work provides a simple etching approach to alter the N configuration and the amount of defects in N-doped CNT, which can be extended to many other energy conversion materials.

摘要 : The development of nonprecious metal catalysts with highly efficient and durable activities is of great importance for high performances of zinc–air batteries. Herein, the N-doped graphene wrapped Fe 3 C/Fe 2 O 3 heterostructure has been designed as a bifunctional oxygen catalyst for zinc–air batteries. In the synthesis process of the catalyst, graphene oxide (GO) can assemble with graphitic carbon nitride (g-C 3 N 4 ) and FeOOH nanorods by the π−π stacking and hydrogen bonds, respectively. The assembly of GO, g-C 3 N 4 and FeOOH nanorods results in nanostructure of carbon layers coated iron species and leads to outstanding durability in both alkaline and acidic media. The synergistic effect of nitrogen doping and Fe 3 C/Fe 2 O 3 heterostructure allows the catalyst (Fe 3 C/Fe 2 O 3 @NGNs) to display high oxygen reduction and evolution reaction activities. The liquid zinc–air battery assembled with the catalyst presented a remarkable peak power density (139.8 mW cm −2 ), large specific capacity (722 mAh g −1 ) and excellent charging–discharging cycling performance. The quasi-solid-state zinc–air battery with the catalyst exhibited an impressive open-circuit voltage and a peak power density. Therefore, the Fe 3 C/Fe 2 O 3 @NGNs catalyst is expected to have a bright future for practical applications in energy conversion devices.

摘要 : Electrochemical pseudocapacitors store energy via intercalation or electrosorption and faradaic charge transfer with redox reactions. MXenes represent the promising intercalation pseudocapacitive electrode materials for supercapacitors due to their ultrahigh theoretical capacitances. Achieving a high capacitance will greatly advance the large-scale applications as in power grids. However, a rational design concept has not been exploited to achieve the theoretical limit. Here, we show how interlayer engineering helps to achieve the limit. Interlayer engineering in this manner simultaneously creates a broadened yet uniform interlayer spacing – providing a “highway” for fast ion diffusion, and incorporates heteroatoms with lower electronegativity – offering “trucks” (redox active sites) on such a “highway” for speeding charge transfer, enabling high capacitance. Following the concept, through annealing the as-prepared Ti3C2Tx MXene under an ammonia atmosphere, the engineered MXene delivers much improved capacitance with excellent rate performance and cyclability. The overall performance of the engineered MXene outperforms that of all other pseudocapacitive electrode materials.

摘要 : Recently, various titanium dioxide (TiO2) nanostructures have received increasing attention in the fields of energy conversion and storage owing to their electrochemical properties. However, these particulate nanomaterials exclusively exist in the powder form, which may cause health risks and environmental hazards. Herein we report a novel, highly elastic bulk form of TiO2 for safe use and easy recycling. Specifically, TiO2 nanofibrous aerogels (NAs) consisting of resiliently bonded, flexible TiO2 nanofibers are constructed, which have an ultralow bulk density, ultrahigh porosity, and excellent elasticity. To promote charge transfer, they are subjected to lithium reduction to generate abundant oxygen vacancies, which can modulate the electronic structure of TiO2, resulting in a conductivity up to 38.2 mS cm−1. As a proof‐of‐concept demonstration, the conductive and elastic TiO2 NAs serve as a new type of self‐supported electrocatalyst for ambient nitrogen fixation, achieving an ammonia yield of 4.19×10−10 mol s−1 cm−2 and a Faradaic efficiency of 20.3 %. The origin of the electrocatalytic activity is revealed by DFT calculations.

摘要 : Mo is an essential trace element for both plants and animals in low concentrations (<5 ppm). However, provoked by uncontrolled industrial waste releases in freshwater or seawater, it is plausible that excessive availability of soluble Mo(VI) would be potentially toxic. In the environment, soluble Mo(VI) is mainly present in anionic forms of molybdate (MoO 4 2? ) and/or tetrathiomolybdate (MoS 4 2? ). The fate and transport of soluble Mo(VI) anions in surface and subsurface aquatic environments is typically controlled by adsorption in acidic soils and sediment. As such, the ability of soils/bed sediments to retain Mo(VI) is a key to determine its general mobility in the aquatic environment. This article reviews the sources and distribution of Mo speciation in solution and Mo(VI) anions adsorption mechanisms in soils and bed sediments, and evaluates the surface adsorption complexation models at the solid-water interface to estimate Mo(VI) anions adsorption in these chemical systems. Mo(VI) anions adsorption mechanisms included MoO 4 2? and MoS 4 2? adsorption by several prevailing adsorbent contents (including clay, Fe, Al oxides, iron sulfide, manganese oxides, and organic matter) of soils and bed sediments, and the influence of the competitive adsorption of other anions (e.g., sulfate, selenate, phosphate, arsenate, silicate, or tungstate). Models to estimate Mo(VI) anions adsorption include the triple layer model (TLM), the diffuse layer model (DLM), the constant capacitance surface complexation model (CCM), and charge distribution multisite complexation model (CD-MUSIC).

摘要 : Novel attapulgite (ATP)/Ce1−xZrxO2 nanocomposite was prepared by a facile homogeneous deposition method using hexamethylenetetramine as precipitator. The catalytic activity of ATP/Ce1−xZrxO2 was investigated by oxygenating methylene blue dye wastewater using O3 as oxidant. HRTEM, XRD, FT-IR, Raman and H2-TPR data reveal significant interactions between CeZrO oxides and ATP support, the evolution of textural, structural and oxidation state as a function of the composition, and the formation of more oxygen vacancies in Ce1−xZrxO2. The molar fraction of Zr4+ demonstrates considerable influence on the degradation rate of the methylene blue. Compared with pure ATP and ATP/CeO2, the ATP/Ce1−xZrxO2 composite remarkably enhances catalytic activity, and a maximum degradation rate of methylene blue at 99% is achieved when the molar fraction x is 0.2.

摘要 : Identifying accurate associations between miRNAs and diseases is beneficial for diagnosis and treatment of human diseases. It is especially important to develop an efficient method to detect the association between miRNA and disease. Traditional experimental method has high precision, but its process is complicated and time-consuming. Various computational methods have been developed to uncover potential associations based on an assumption that similar miRNAs are always related to similar diseases. In this paper, we propose an accurate method, MDA-SKF, to uncover potential miRNA-disease associations. We first extract three miRNA similarity kernels (miRNA functional similarity, miRNA sequence similarity, Hamming profile similarity for miRNA) and three disease similarity kernels (disease semantic similarity, disease functional similarity, Hamming profile similarity for disease) in two subspaces, respectively. Then, due to limitations that some initial information may be lost in the process and some noises may be exist in integrated similarity kernel, we propose a novel Similarity Kernel Fusion (SKF) method to integrate multiple similarity kernels. Finally, we utilize the Laplacian Regularized Least Squares (LapRLS) method on the integrated kernel to find potential associations. MDA-SKF is evaluated by three evaluation methods, including global leave-one-out cross validation (LOOCV) and local LOOCV and 5-fold cross validation (CV), and achieves AUCs of 0.9576, 0.8356, and 0.9557, respectively. Compared with existing seven methods, MDA-SKF has outstanding performance on global LOOCV and 5-fold. We also test case studies to further analyze the performance of MDA-SKF on 32 diseases. Furthermore, 3200 candidate associations are obtained and a majority of them can be confirmed. It demonstrates that MDA-SKF is an accurate and efficient computational tool for guiding traditional experiments.

摘要 : Graphene fiber-based supercapacitors (SCs) are rising as having the greatest potential for portable/wearable energy storage devices. However, their rate performance is not well pleasing, which greatly impedes their broad practical applications. Herein, three-dimensional porous carbon nanotube/reduced graphene oxide fibers were prepared by a nonsolvent-induced rapid phase separation method followed by hydrazine vapor reduction. Benefitting from their three-dimensional porous structure, large specific surface area, and high conductivity, the fabricated SC exhibits a high volume capacitance of 54.9 F cm–3 and high energy and power densities (4.9 mW h cm–3 and 15.5 W cm–3, respectively). Remarkably, the SC works well at a high scan rate of 50 V s–1 and shows a fast frequency response with a short time constant of 78 ms. Furthermore, the fiber-shaped SC also exhibits very stable electrochemical performances when it is subjected to mechanical bending and succeeding straightening process, indicating its great potential application in flexible electronic devices.