Developing anodic oxygen evolution reaction (OER) electrocatalysts with high catalytic activities is of great importance for effective water splitting. Compared with the water‐oxidation ...electrocatalysts that are commonly utilized in alkaline conditions, the ones operating efficiently under neutral or near neutral conditions are more environmentally friendly with less corrosion issues. This review starts with a brief introduction of OER, the importance of OER in mild‐pH media, as well as the fundamentals and performance parameters of OER electrocatalysts. Then, recent progress of the rational design of electrocatalysts for OER in mild‐pH conditions is discussed. The chemical structures or components, synthetic approaches, and catalytic performances of the OER catalysts will be reviewed. Some interesting insights into the catalytic mechanism are also included and discussed. It concludes with a brief outlook on the possible remaining challenges and future trends of neutral or near‐neutral OER electrocatalysts. It hopefully provides the readers with a distinct perspective of the history, present, and future of OER electrocatalysts at mild conditions.
Electrocatalytic water oxidation under environmentally‐friendly conditions has received considerable recent research attention. This paper reviews recent advances in the design and development of water oxidation electrocatalysts operating at mild pH, and current challenges and future research directions are also provided.
When tackling high dimensionality in data mining, online feature selection which deals with features flowing in one by one over time, presents more advantages than traditional feature selection ...methods. However, in real-world applications, such as fraud detection and medical diagnosis, the data is high-dimensional and highly class imbalanced, namely there are many more instances of some classes than others. In such cases of class imbalance, existing online feature selection algorithms usually ignore the small classes which can be important in these applications. It is hence a challenge to learn from high-dimensional and class imbalanced data in an online manner. Motivated by this, we first formalize the problem of online streaming feature selection for class imbalanced data, and then present an efficient online feature selection framework regarding the dependency between condition features and decision classes. Meanwhile, we propose a new algorithm of Online Feature Selection based on the Dependency in K nearest neighbors, called K-OFSD. In terms of Neighborhood Rough Set theory, K-OFSD uses the information of nearest neighbors to select relevant features which can get higher separability between the majority class and the minority class. Finally, experimental studies on seven high-dimensional and class imbalanced data sets show that our algorithm can achieve better performance than traditional feature selection methods with the same numbers of features and state-of-the-art online streaming feature selection algorithms in an online manner.
An electrochemiluminescence (ECL) sensor provides a sensitive and convenient method for early diagnosis of diseases; however, it is still a challenge to develop simple and sensitive sensing platforms ...based on efficient ECL signals and luminophore groups. Porphyrin-based metal–organic frameworks (MOFs) show great potential in ECL sensing; however, the mechanism and structure–activity relationship, as well as application, are rarely reported. Herein, hydrothermal reactions obtained porphyrin Zr-MOFs (PCN-222) with different specific surface areas, pore sizes, structures, and surface charge states by tuning the reaction time were developed, which served both as the ECL luminophore, coreaction promoter for S2O8 2–, and a connection in the ECL immunoassay. By progressively controlling the condition of the hydrothermal reaction, PCN-222 with large surface area-abundant micropores can be obtained, which has good conductivity and positively charged surfaces, obtaining excellent ECL performance. The ECL performance and the enhancement mechanism were investigated in detail. Using PCN-222-6h with the best ECL intensity as the immobilization matrix for the aptamer, a highly sensitive and selective assay for thrombin was developed. The decrease of the ECL signal was logarithmically linear with the concentration of thrombin in the range from 50 fg mL–1 to 100 pg mL–1 with a low detection limit of 2.48 fg/mL. This proposed strategy provides a brand new approach for tuning of the structures of MOFs as effective ECL signal probes, thus providing wider possibilities for effective ECL immunoassays in the detection of other biomarkers in diagnosis of diseases.
Recently, rapid improvements in technology and decrease in sequencing costs have made RNA-Seq a widely used technique to quantify gene expression levels. Various normalization approaches have been ...proposed, owing to the importance of normalization in the analysis of RNA-Seq data. A comparison of recently proposed normalization methods is required to generate suitable guidelines for the selection of the most appropriate approach for future experiments.
In this paper, we compared eight non-abundance (RC, UQ, Med, TMM, DESeq, Q, RPKM, and ERPKM) and two abundance estimation normalization methods (RSEM and Sailfish). The experiments were based on real Illumina high-throughput RNA-Seq of 35- and 76-nucleotide sequences produced in the MAQC project and simulation reads. Reads were mapped with human genome obtained from UCSC Genome Browser Database. For precise evaluation, we investigated Spearman correlation between the normalization results from RNA-Seq and MAQC qRT-PCR values for 996 genes. Based on this work, we showed that out of the eight non-abundance estimation normalization methods, RC, UQ, Med, TMM, DESeq, and Q gave similar normalization results for all data sets. For RNA-Seq of a 35-nucleotide sequence, RPKM showed the highest correlation results, but for RNA-Seq of a 76-nucleotide sequence, least correlation was observed than the other methods. ERPKM did not improve results than RPKM. Between two abundance estimation normalization methods, for RNA-Seq of a 35-nucleotide sequence, higher correlation was obtained with Sailfish than that with RSEM, which was better than without using abundance estimation methods. However, for RNA-Seq of a 76-nucleotide sequence, the results achieved by RSEM were similar to without applying abundance estimation methods, and were much better than with Sailfish. Furthermore, we found that adding a poly-A tail increased alignment numbers, but did not improve normalization results.
Spearman correlation analysis revealed that RC, UQ, Med, TMM, DESeq, and Q did not noticeably improve gene expression normalization, regardless of read length. Other normalization methods were more efficient when alignment accuracy was low; Sailfish with RPKM gave the best normalization results. When alignment accuracy was high, RC was sufficient for gene expression calculation. And we suggest ignoring poly-A tail during differential gene expression analysis.
Scant attention has been paid to how risk perceptions of public health crises may affect people's mental health.
: The aims of this study are to (1) construct a conceptual framework for risk ...perception and depression of people in public health crises, (2) examine how the mental health of people in the crisis of Coronavirus Disease 2019 (COVID-19) is affected by risk perception and its associated factors, including distance perception of the crisis and support of prevention and control policies, and (3) propose policy recommendations on how to deal with psychological problems in the current COVID-19 crisis.
: Online questionnaire survey was implemented. A total of 6373 people visited the questionnaire online, 1115 people completed the questionnaire, and the number of valid questionnaires was 1081. Structural equation modeling was employed for data analysis.
: Risk perception and its associated factors significantly affect the mental health of people in public health crises. Specifically, (1) distance perception of public health crises is negatively associated with depression among people, (2) affective risk perception is positively associated with depression of people in public health crises, (3) cognitive risk perception is negatively associated with depression of people in public health crises, and (4) support of prevention and control policies is negatively associated with depression of people in public health crises.
: The findings of this study suggest that risk perception plays an important role in affecting the mental health of people in a public health crisis. Therefore, health policies aiming to improve the psychological wellbeing of the people in a public health crisis should take risk perception into consideration.
Herein, we report a nongenetic and real-time approach for imaging protein dimerization on living cell surfaces by aptamer recognition and proximity-induced DNA assembly. We use the aptamer specific ...for the receptor monomer as a recognition probe. When receptor dimerization occurs, the dimeric receptors bring two aptamer probes into close proximity, thereby triggering dynamic DNA assembly. The proposed approach was successfully applied to visualize dimerization of Met receptor and transforming growth factor-β type II receptor. This approach allows us to image the two states (monomer/dimer) of a receptor protein on living cell surfaces in real time, opening a universal method for further investigation of protein dimerization and the corresponding activation processes in signal transduction.
Age synthesis is a challenging task due to the complicated and non-linear transformation in the human aging process. Aging information is usually reflected in local facial parts, such as wrinkles at ...the eye corners. However, these local facial parts contribute less in previous GAN-based methods for age synthesis. To address this issue, we propose a wavelet-domain global and local consistent age generative adversarial network (WaveletGLCA-GAN), in which one global specific network and three local specific networks are integrated together to capture both global topology information and local texture details of human faces. Different from the most existing methods that modeling age synthesis in image domain, we adopt wavelet transform to depict the textual information in frequency domain. Moreover, five types of losses are adopted: 1) adversarial loss aims to generate realistic wavelets; 2) identity preserving loss aims to better preserve identity information; 3) age preserving loss aims to enhance the accuracy of age synthesis; 4) pixel-wise loss aims to preserve the background information of the input face; and 5) the total variation regularization aims to remove ghosting artifacts. Our method is evaluated on three face aging datasets, including CACD2000, Morph, and FG-NET. Qualitative and quantitative experiments show the superiority of the proposed method over other state-of-the-arts.
Epigenetic control of enhancers alters neuronal functions and may be involved in Alzheimer's disease (AD). Here, we identify enhancers in neurons contributing to AD by comprehensive fine-mapping of ...DNA methylation at enhancers, genome-wide. We examine 1.2 million CpG and CpH sites in enhancers in prefrontal cortex neurons of individuals with no/mild, moderate, and severe AD pathology (n = 101). We identify 1224 differentially methylated enhancer regions; most of which are hypomethylated at CpH sites in AD neurons. CpH methylation losses occur in normal aging neurons, but are accelerated in AD. Integration of epigenetic and transcriptomic data demonstrates a pro-apoptotic reactivation of the cell cycle in post-mitotic AD neurons. Furthermore, AD neurons have a large cluster of significantly hypomethylated enhancers in the DSCAML1 gene that targets BACE1. Hypomethylation of these enhancers in AD is associated with an upregulation of BACE1 transcripts and an increase in amyloid plaques, neurofibrillary tangles, and cognitive decline.
A magnetic adsorbent based on a C-nanofiber (Fe3O4@C–NFs) nanocomposite was synthesized using a simple one-pot co-precipitation method. The characterized results showed that the obtained ...C–nanofiber–coated magnetic nanoparticles had many attractive features such as a large specific surface area and a highly interwoven and branched mesoporous structure, as well as distinguished magnetism. The nanocomposite was then used as an adsorbent in the magnetic solid phase extraction (MSPE) of four typical tetracyclines (oxytetracycline, tetracycline, chlortetracycline, and doxycycline) in aquatic products. The TCs in the extract were determined using ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS). Experimental variables of MSPE, including the sorbent amount, pH condition, adsorption and desorption time, and desorption solvent, were investigated and optimized systematically. The method validation indicated that the developed method showed good linearity (R2 > 0.995) in the range of 1.0–200 ng/mL. The average recoveries at the spiked levels ranged from 90.7% to 102.7% with intra-day and inter-day relative standard deviations (RSDs, n = 6) ranging from 3.72% to 8.17% and 4.20% to 9.69%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) for the four kinds of TCs were 0.7 μg/kg and 2.0 μg/kg, respectively. Finally, MSPE based on C-nanofiber-coated magnetic nanoparticles was successfully applied to TC analysis in real aquatic products (grass carp, large yellow croaker, snakehead, mandarin fish, Penaeus vannamei, swimming crab, etc.). Compared with traditional extraction methods, the proposed method for TC analysis in aquatic products is more sensitive, effective, recyclable, and environmentally friendly.
A novel catalyst of FeCo nanoparticles (FeCo NPs) incorporated porous nanocages (FeCo NPs@PNC) was first synthesized by encapsulating of FeCo alloy into ZIF-8 and further carbonation of the ...composite. The FeCo NPs@PNC displays enhanced intrinsic oxidase-like activity compared to the individual FeCo NPs and porous nanocages (PNC). The FeCo NPs@PNC can catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to oxidized TMB (oxTMB) without H2O2, producing a blue color with a maximum absorption peak at 652 nm. The catalytic mechanism was investigated and it found that the intermediate (O2·-) produced from the catalytic process in the system of TMB-O2-FeCo NPs@PNC can accelerate the oxidation of TMB to oxTMB. However, ascorbic acid (AA) can reduce the oxTMB and result in a conspicuous blue color fading. Therefore, a novel colorimetric platform was constructed to quantify AA with the linear range of 0.5–28 μM and detection limit of 0.38 μM (at 3σ/m). Owing to the alkaline phosphatase (ALP) can catalyze the hydrolysis of AA 2-phosphate (AAP) into AA, ALP can also be quantified by the above method. And the linear range for ALP is 0.6–10 U L−1 and the limit of detection is 0.49 U L−1. The FeCo NPs@PNC also shows excellent stability and reproducibility. This study provides a new alternative oxidase mimetic on the basis of easily obtained metal-organic frameworks derivatives to replace the expensive natural enzymes and noble metal based nanoenzymes, which will show great potential in biological assays.
(A) The synthesis process of FeCo NPs@PNC. (B) The obtained FeCo NPs@PNC have the intrinsic oxidase-like activity which can catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) without H2O2 producing typical color reaction. Ascorbic acid (AA) can reduce the oxTMB and result in a conspicuous blue color fading. The alkaline phosphatase (ALP) can catalyze the hydrolysis of AA-2-phosphate (AAP) into AA. Therefore, novel colorimetric biosensing platform was constructed based on FeCo NPs@PNC-TMB system to quantify AA and ALP. Display omitted
•FeCo NPs@PNC was first synthesized with enhanced intrinsic oxidase-like activity.•FeCo NPs@PNC can catalytically TMB oxidization in the absence of H2O2.•The oxidase-like activity stems from the synergistic effect of FeCo NPs and PNC.•The incorporation of FeCo NPs into MOFs solved the instability of FeCo NPs.•FeCo NPs@PNC-based novel colorimetric platform was built for AA and ALP detection.
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