Attentional bias for rejection and sad words in Chinese left-behind children with depression.

BACKGROUND: This study aimed to examine attentional bias (AB) for sad and social rejection words in Chinese left-behind children (LBC) with depression. METHOD: We investigated both stimulus specificity and components of AB in different groups using a cross-sectional design. Data were drawn from a school assessment of depression and anxiety, from which we selected LBC with depression (n = 40), LBC without depression (n = 33), a control group with depression (n = 31), and a control group without depression (n = 37). AB was measured with a dot-probe task covering two stimulus types (sad and rejection). RESULTS: The analysis of AB scores revealed a significant three-way interaction (LBC × depression × word type), F(1, 137) = 4.00, p = 0.047, η2 = 0.028, with depressed non-LBC exhibiting a significant depression × word type interaction, F(1, 66) = 4.67, p = 0.034, η2 = 0.066, while the depression × word type interaction was not significant in LBC, F(1, 71) = 0.18, p = 0.675, η2 = 0.002. Depressed children living with their parents showed AB towards sad words but not rejection words, while depressed LBC showed greater AB towards both rejection and sad words. CONCLUSIONS: The findings provide evidence that an AB towards sad information is critically involved in the depressed LBC. Compared with non-LBC depressed individuals, an AB for rejection may be involved as a risk factor in the LBC. It sheds light on the effective intervention programmes for LBC's depression and have important practical significance for reducing depression and improving the mental health of LBC.

Efficacy and confounding factors of CT attenuation value differences in distinguishing acute and old vertebral compression fractures: a retrospective study.

PURPOSE: To evaluate the influence of various factors on CT attenuation values (HUs) of acute and old fracture vertebra, and to determine the efficacy of HU differences (△HUs) in the differentiation of the two type of fractures. MATERIALS AND METHODS: A total of 113 acute and 71 old fracture vertebrae confirmed by MRI were included. Four HUs measured at the mid-sagittal, upper 1/3 axial, mid-axial, and lower 1/3 axial planes of each vertebra were obtained. The △HUs between fracture vertebra and its control counterpart was calculated. Receiver operating characteristic (ROC) curve analysis was used and the areas under the ROC curve (AUC) were calculated to evaluate the efficacy of HUs and △HUs. To evaluate the effect of height reduction, region, age and gender on HUs and △HUs, one-way analysis of variance, Pearson correlation analysis and t-test were used. RESULTS: The HUs and △HUs at the upper 1/3 axial plane achieved the highest AUCs of 0.801 and 0.839, respectively. The HUs decreased gradually from Thoracic to Lumbar in control group of acute fracture. While no significant differences were found in the HUs among the 3 localizations in both fracture groups (all P > 0.05). The HUs were negatively correlated with age in all groups. The HUs of male were significantly higher than female patients in all groups (all P < 0.05). While △HU was not significantly different between males and females (all P > 0.05). CONCLUSION: The vertebral HUs at the upper 1/3 axial plane are more likely to identify acute fractures. △HUs were beneficial in eliminating interfering factors.

Boron Coordination Effect in Ni-Nx Doped Graphene Catalysts on the ORR Performance Based on DFT Calculations.

The coordination atoms of metal active site in transition metal N-doped carbon single atom electrocatalysts play a vital role in dominating the catalytic performance of oxygen reduction reaction (ORR) at the cathode of fuel cells or metal-air cells. In view of weak adsorption ability of Ni active site in NiN4 -C catalysts to oxygen intermediate states, herein we introduce boron atoms with smaller electronegativity than N and C atoms to modulate the local coordination environment and electronic structures of Ni site. First-principles density functional calculations reveal that both B substitution for N atoms (NiN2 B2 -C) and B coordinating with N and C (NiN4 B8 -C) can effectively optimize the Gibbs free energy of oxygen intermediate states and hence improve the catalytic activity of the materials. In addition, we propose that the trend change in catalytic activity is mainly governed by the filling of antibonding orbitals between Ni-3d and O-2p states near the Fermi level.

A high activity zinc transporter OsZIP9 mediates zinc uptake in rice.

Zinc (Zn) is an essential micronutrient for most organisms including humans, and Zn deficiency is widespread in human populations, particularly in underdeveloped regions. Cereals such as rice (Oryza sativa) are the major dietary source of Zn for most people. However, the molecular mechanism underlying Zn uptake in rice is still not fully understood. Here, we report that a member of the ZIP (ZRT, IRT-like protein) family, OsZIP9, contributes to Zn uptake in rice. It was expressed in the epidermal and exodermal cells of lateral roots, localized in the plasma membrane and induced during Zn deficiency. Yeast-expressed OsZIP9 showed much higher Zn influx transport activity than other rice ZIP proteins in a wide range of Zn concentrations. OsZIP9 knockout rice plants showed a significant reduction in growth at low Zn concentrations, but could be rescued by a high Zn supply. Compared with the wild type, accumulation of Zn in root, shoot and grain was much lower in knockout lines, particularly with a low supply of Zn under both hydroponic and paddy soil conditions. OsZIP9 also showed Co uptake activity. Natural variation of OsZIP9 expression level is highly associated with Zn content in milled grain among rice varieties in the germplasm collection. Taken together, these results show that OsZIP9 is an important influx transporter responsible for the take up of Zn and Co from external media into root cells.

Engineering Bimetallic NiFe-Based Hydroxides/Selenides Heterostructure Nanosheet Arrays for Highly-Efficient Oxygen Evolution Reaction.

Developing cost-effective and high-efficiency electrocatalysts toward alkaline oxygen evolution reaction (OER) is crucial for water splitting. Amorphous bimetallic NiFe-based (oxy)hydroxides have excellent OER activity under alkaline media, but their poorly electrical conductivity impedes the further improvement of their catalytic performance. Herein, a bimetallic NiFe-based heterostructure electrocatalyst that is composed of amorphous NiFe(OH)x and crystalline pyrite (Ni, Fe)Se2 nanosheet arrays is designed and constructed. The catalyst exhibits an outstanding OER performance, only requiring low overpotentials of 180, 220, and 230 mV at the current density of 10, 100, and 300 mA cm-2 and a low Tafel slope of 42 mV dec-1 in 1 m KOH, which is among the state-of-the-art OER catalysts. Based on the experimental and theoretical results, the electronic coupling at the interface that leads to the increased electrical conductivity and the optimized adsorption free energies of the oxygen-contained intermediates plays a crucial role in enhancing the OER activities. This work focusing on improving the OER performance via engineering amorphous-crystalline bimetallic heterostructure may provide some inspiration for reasonably designing advanced electrocatalysts.

Genome-Wide Association Studies Reveal the Genetic Basis of Ionomic Variation in Rice.

Rice (Oryza sativa) is an important dietary source of both essential micronutrients and toxic trace elements for humans. The genetic basis underlying the variations in the mineral composition, the ionome, in rice remains largely unknown. Here, we describe a comprehensive study of the genetic architecture of the variation in the rice ionome performed using genome-wide association studies (GWAS) of the concentrations of 17 mineral elements in rice grain from a diverse panel of 529 accessions, each genotyped at ∼6.4 million single nucleotide polymorphism loci. We identified 72 loci associated with natural ionomic variations, 32 that are common across locations and 40 that are common within a single location. We identified candidate genes for 42 loci and provide evidence for the causal nature of three genes, the sodium transporter gene Os-HKT1;5 for sodium, Os-MOLYBDATE TRANSPORTER1;1 for molybdenum, and Grain number, plant height, and heading date7 for nitrogen. Comparison of GWAS data from rice versus Arabidopsis (Arabidopsis thaliana) also identified well-known as well as new candidates with potential for further characterization. Our study provides crucial insights into the genetic basis of ionomic variations in rice and serves as an important foundation for further studies on the genetic and molecular mechanisms controlling the rice ionome.

Insights into salvianolic acid B biosynthesis from chromosome-scale assembly of the Salvia bowleyana genome.

Salvia bowleyana is a traditional Chinese medicinal plant that is a source of nutritional supplements rich in salvianolic acid B and a potential experimental system for the exploration of salvianolic acid B biosynthesis in the Labiatae. Here, we report a high-quality chromosome-scale genome assembly of S. bowleyana covering 462.44 Mb, with a scaffold N50 value of 57.96 Mb and 44,044 annotated protein-coding genes. Evolutionary analysis revealed an estimated divergence time between S. bowleyana and its close relative S. miltiorrhiza of ~3.94 million years. We also observed evidence of a whole-genome duplication in the S. bowleyana genome. Transcriptome analysis showed that SbPAL1 (PHENYLALANINE AMMONIA-LYASE1) is highly expressed in roots relative to stem and leaves, paralleling the location of salvianolic acid B accumulation. The laccase gene family in S. bowleyana outnumbered their counterparts in both S. miltiorrhiza and Arabidopsis thaliana, suggesting that the gene family has undergone expansion in S. bowleyana. Several laccase genes were also highly expressed in roots, where their encoded proteins may catalyze the oxidative reaction from rosmarinic acid to salvianolic acid B. These findings provide an invaluable genomic resource for understanding salvianolic acid B biosynthesis and its regulation, and will be useful for exploring the evolution of the Labiatae.

Diabetes downregulates peptide transporter 1 in the rat jejunum: possible involvement of cholate-induced FXR activation.

Peptide transporter 1 (PepT1), highly expressed on the apical membrane of enterocytes, is involved in energy balance and mediates intestinal absorption of peptidomimetic drugs. In this study, we investigated whether and how diabetes affected the function and expression of intestinal PepT1. Diabetes was induced in rats by combination of high-fat diet and low dose streptozocin injection. Pharmacokinetics study demonstrated that diabetes significantly decreased plasma exposures of cephalexin and acyclovir following oral administration of cephalexin and valacyclovir, respectively. Single-pass intestinal perfusion analysis showed that diabetes remarkably decreased cephalexin absorption, which was associated with decreased expression of intestinal PepT1 protein. We assessed the levels of bile acids in intestine of diabetic rats, and found that diabetic rats exhibited significantly higher levels of chenodeoxycholic acid (CDCA), cholic acid (CA) and glycocholic acid (GCA), and lower levels of lithocholic acid (LCA) and hyodeoxycholic acid (HDCA) than control rats; intestinal deoxycholic acid (DCA) levels were unaltered. In Caco-2 cells, the 6 bile acids remarkably decreased expression of PepT1 protein with CDCA causing the strongest inhibition, whereas TNF-α, LPS and insulin little affected expression of PepT1 protein; short-chain fatty acids induced rather than decreased expression of PepT1 protein. Farnesoid X receptor (FXR) inhibitor glycine-ß-muricholic acid or FXR knockdown reversed the downregulation of PepT1 expression by CDCA and GW4064 (another FXR agonist). In diabetic rats, the expression of intestinal FXR protein was markedly increased. Oral administration of CDCA (90, 180 mg·kg-1·d-1, for 3 weeks) dose-dependently decreased the expression and function of intestinal PepT1 in rats. In conclusion, diabetes impairs the expression and function of intestinal PepT1 partly via CDCA-mediated FXR activation.

Open Surgery Versus Closed Treatment of Unilateral Mandibular Condyle Fractures.

PURPOSE: The aim of this meta-analysis was to evaluate the efficacy of open surgery and closed treatment for unilateral moderately displaced mandibular condyle fractures. METHODS: PubMed, Embase, and Cochrane Library databases were searched according to PRISMA guidelines from inception to October, 2018. Inclusion criteria were based on humans randomized controlled trials in the English literature. Pertinent data were collected and the incidence of the complications was calculated. RESULTS: A total of 6 studies with 227 patients were included in the meta-analysis. The results showed that there were no significant differences in incidence of malocclusion (odds ratio [OR], 0.33; 95% confidence interval [CI]: 0.07-1.46; P = 0.14). However, open surgery group had a better maximal mouth opening (WMD = 3.82, 95% CI: 1.93-5.71, P < 0.01), protrusion (WMD = 1.16, 95% CI: 0.42-1.89, P < 0.01) and sum of both laterotrusions (WMD: 2.50, 95% CI: 1.77-3.22, P < 0.01). And the incidence of temporomandibular joint pain was lower than closed treatment group (OR: 0.15, 95% CI: 0.06-0.37, P < 0.01). CONCLUSIONS: Compared with closed treatment, open surgery has significant advantages in improving mouth opening and mandibular movement, and reducing the incidence of temporomandibular joint pain, provided that open surgery was a promising application in treatment of unilateral moderately displaced mandibular condyle fractures.

A nonsurgical and nonpharmacological care bundle for preventing upper urinary tract damage in patients with spinal cord injury and neurogenic bladder.

AIM: To establish a care bundle in spinal cord injury patients with neurogenic bladder to avoid upper urinary tract damage and to provide guidance for health care staff in use of nonsurgical and nonpharmacological adjunctive strategies to improve patients' clinical outcomes. BACKGROUND: Prevention of upper urinary tract damage is critical in the management of spinal cord injury patients with a neurogenic bladder, but there are no authoritative guidelines or high-quality randomized controlled trials. DESIGN: The study was conducted on the basis of Fulbrook and Mooney's seven-step method for care bundle development. DATA SOURCES: The databases PubMed, Embase, Science Citation Index, the Cumulative Index to Nursing and Allied Health Literature, the National Guideline Clearinghouse, the Cochrane Library, China Biology Medicine, China National Knowledge Infrastructure, and China Dissertation Database were searched from the date of each database's inception to April 2017. REVIEW METHODS: We evaluated the literature according to the Joanna Briggs Institute evidence pre-ranking and grade recommendation system (2014 version). The results were examined using a self-designed data extraction. RESULTS: A three-element cluster including clean intermittent catheterization, bladder function training, and transcutaneous low-frequency pulsed electrical stimulation was formed. CONCLUSION: The development of this bundle can provide a scientific basis for effective prevention of neurogenic upper urinary tract damage in clinical practice.

Prediction of Atorvastatin Pharmacokinetics in High-Fat Diet and Low-Dose Streptozotocin-Induced Diabetic Rats Using a Semiphysiologically Based Pharmacokinetic Model Involving Both Enzymes and Transporters.

Atorvastatin is a substrate of cytochrome P450 3a (CYP3a), organic anion-transporting polypeptides (OATPs), breast cancer-resistance protein (BCRP), and P-glycoprotein (P-gp). We aimed to develop a semiphysiologically based pharmacokinetic (semi-PBPK) model involving both enzyme and transporters for predicting the contributions of altered function and expression of CYP3a and transporters to atorvastatin transport in diabetic rats by combining high-fat diet feeding and low-dose streptozotocin injection. Atorvastatin metabolism and transport parameters comes from in situ intestinal perfusion, primary hepatocytes, and intestinal or hepatic microsomes. We estimated the expressions and functions of these proteins and their contributions. Diabetes increased the expression of hepatic CYP3a, OATP1b2, and P-gp but decreased the expression of intestinal CYP3a, OATP1a5, and P-gp. The expression and function of intestinal BCRP were significantly decreased in 10-day diabetic rats but increased in 22-day diabetic rats. Based on alterations in CYP3a and transporters by diabetes, the developed semi-PBPK model was successfully used to predict atorvastatin pharmacokinetics after oral and intravenous doses to rats. Contributions to oral atorvastatin PK were intestinal OATP1a5 < intestinal P-gp < intestinal CYP3a < hepatic CYP3a < hepatic OATP1b2 < intestinal BRCP. Contributions of decreased expression and function of intestinal CYP3a and P-gp by diabetes to oral atorvastatin plasma exposure were almost attenuated by increased expression and function of hepatic CYP3a and OATP1b2. Opposite alterations in oral plasma atorvastatin exposure in 10- and 22-day diabetic rats may be explained by altered intestinal BCRP. In conclusion, the altered atorvastatin pharmacokinetics by diabetes was the synergistic effects of altered intestinal or hepatic CYP3a and transporters and could be predicted using the developed semi-PBPK.

Impairment of Intestinal Monocarboxylate Transporter 6 Function and Expression in Diabetic Rats Induced by Combination of High-Fat Diet and Low Dose of Streptozocin: Involvement of Butyrate-Peroxisome Proliferator-Activated Receptor-γ Activation.

Generally, diabetes remarkably alters the expression and function of intestinal drug transporters. Nateglinide and bumetanide are substrates of monocarboxylate transporter 6 (MCT6). We investigated whether diabetes down-regulated the function and expression of intestinal MCT6 and the possible mechanism in diabetic rats induced by a combination of high-fat diet and low-dose streptozocin. Our results indicated that diabetes significantly decreased the oral plasma exposure of nateglinide. The plasma peak concentration and area under curve in diabetic rats were 16.9% and 28.2% of control rats, respectively. Diabetes significantly decreased the protein and mRNA expressions of intestinal MCT6 and oligopeptide transporter 1 (PEPT1) but up-regulated peroxisome proliferator-activated receptor γ (PPARγ) protein level. Single-pass intestinal perfusion demonstrated that diabetes prominently decreased the absorption of nateglinide and bumetanide. The MCT6 inhibitor bumetanide, but not PEPT1 inhibitor glycylsarcosine, significantly inhibited intestinal absorption of nateglinide in rats. Coadministration with bumetanide remarkably decreased the oral plasma exposure of nateglinide in rats. High concentrations of butyrate were detected in the intestine of diabetic rats. In Caco-2 cells (a human colorectal adenocarcinoma cell line), bumetanide and MCT6 knockdown remarkably inhibited the uptake of nateglinide. Butyrate down-regulated the function and expression of MCT6 in a concentration-dependent manner but increased PPARγ expression. The decreased expressions of MCT6 by PPARγ agonist troglitazone or butyrate were reversed by both PPARγ knockdown and PPARγ antagonist 2-chloro-5-nitro-N-phenylbenzamide (GW9662). Four weeks of butyrate treatment significantly decreased the oral plasma concentrations of nateglinide in rats, accompanied by significantly higher intestinal PPARγ and lower MCT6 protein levels. In conclusion, diabetes impaired the expression and function of intestinal MCT6 partly via butyrate-mediated PPARγ activation, decreasing the oral plasma exposure of nateglinide.

Comprehensive analysis of variation of cadmium accumulation in rice and detection of a new weak allele of OsHMA3.

Excessive cadmium (Cd) accumulation in rice poses a potential threat to human health. Rice varieties vary in their Cd content, which depends mainly on root-to-shoot translocation of Cd. However, cultivars accumulating high Cd in the natural population have not been completely investigated. In this study, we analyzed the variation in Cd accumulation in a diverse panel of 529 rice cultivars. Only a small proportion (11 of 529) showed extremely high root-to-shoot Cd transfer rates, and in seven of these cultivars this was caused by two known OsHMA3 alleles. Using quantitative trait loci mapping, we identified a new OsHMA3 allele that was associated with high Cd accumulation in three of the remaining cultivars. Using heterologous expression in yeast and comparative analysis among different rice cultivars, we observed that this new allele was weak at both the transcriptional and protein levels compared with the functional OsHMA3 genotypes. The weak Cd transport activity was further demonstrated to be caused by a Gly to Arg substitution at position 512. Our study comprehensively analyzed the variation in root-to-shoot Cd translocation rates in cultivated rice and identified a new OsHMA3 allele that caused high Cd accumulation in a few rice cultivars.

Overexpression of acetyl-CoA carboxylase increases fatty acid production in the green alga Chlamydomonas reinhardtii.

Chlamydomonas reinhardtii is a photosynthetic unicellular model algae with multiple biotechnological advantages, and its fatty acids can be used to produce biofuels. Numerous studies suggest that acetyl-coA carboxylase (ACCa) catalyzes the first committed and rate-limiting step of fatty acid biosynthesis, thereby playing a central role in oil accumulation. Here, we cloned and overexpressed ACCa in C. reinhardtii to directly evaluate its effect on fatty acid synthesis. GC-MS analysis found that the unsaturated FAs contents of the CW15-24 and CW15-85 strains were 55.45% and 56.15%, which were significantly enriched compared to the wild type CW15 (48.39%). Under the optimized conditions, the content of lipid by overexpressed the ACCa gene in the mutant CW15-85 (0.46 g/l) was 1.16-fold greater than control through optimization of N and P sources. Altogether, our data clearly demonstrate that ACCa overexpression in C. reinhardtii can directly increase the synthesis of fatty acids.

Trans-Oral Robotic Surgery of Submandibular Gland Removal With Preservation of Sublingual Gland and Wharton's Duct.

In surgical removal of a submandibular gland, trans-cervical approach has esthetic problem and existing trans-oral approaches are extensively invasive. The authors have used trans-oral robotic surgery to remove the submandibular gland with preservation of the sublingual gland and the Wharton's duct, and hereby report the case and discuss our preliminary experiences.

Computer-Aided Freehand Maxillary Repositioning.

The authors aimed to test the hypothesis that in orthognathic surgery the maxilla could be repositioned using spatial distances from Glabella to 3 maxillary dental landmarks as references. An asymmetric skeletal Class 3 malocclusion patient was involved and bimaxillary orthognathic surgery was planned. Virtual surgery was simulated and spatial distances from Glabella to midpoint of the upper dentition (U0) and bilateral medial-buccal cusp of the first molar (6L and 6R) were measured. These distances were used as the repositioning references and were imported intraoperatively into a digital caliper after the maxilla was mobilized, the repositioning of maxilla was manipulated till all the true spatial distances reached the references. Postoperative computed tomography head model were superimposed onto the planned head model, the maxillary repositioning error was assessed using spatial distances between the pre- and postoperative dental landmarks. The asymmetric skeletal Class 3 malocclusion was corrected through bimaxillary surgery and the errors at U0, 6R and 6L was 1.37, 1.79, and 1.45 mm. The maxilla could be repositioned using spatial distances from Glabella to 3 maxillary dental landmarks as references.

Does Property Return Affect Seller Behavior? An Empirical Study of China's Real Estate Market.

This paper examines the relationship between property return and seller behavior and aims to test the disposition effect in China's real estate market. Using transaction data in Beijing, we find that loss properties have a lower sell propensity relative to gain properties, confirming the existence of the disposition effect. We also find that the disposition effect is more pronounced in samples with shorter holding periods. Sellers with financial constraints and popular projects are more likely to show the disposition effect. Furthermore, we find that sellers exhibit loss aversion; specifically, sellers with loss properties are likely to set a higher listing price, which provides indirect evidence for the disposition effect.

Quality evaluation index development for nutritional management in patients with nasopharyngeal carcinoma during peri-radiotherapy.

OBJECTIVES: It is necessary to construct an evaluation index for patients with nasopharyngeal carcinoma during peri-radiotherapy to provide a reference for the evaluation of the quality of nutritional management of patients with nasopharyngeal carcinoma during peri-radiotherapy. The aim of this study was to construct a set of scientific, comprehensive, and feasible indicators for evaluating the quality of nutrition management in patients with nasopharyngeal carcinoma during peri-radiotherapy to provide a unified reference basis for objective nutritional evaluation of these patients during the peri-radiotherapy period and to provide insights to the clinical treatment and care of these patients. METHODS: A multidisciplinary research team was set up from December 2021 to April 2022. We took the three-dimensional quality structure model as the theoretical framework; based on the literature review, the first draft of the nutrition management quality evaluation index for patients with nasopharyngeal carcinoma during peri-radiotherapy was formed by a semi-structured interview. The Delphi correspondence method was used to survey 18 experts from 12 cities in China. The multidimensional analytical hierarchy process was used to determine the evaluation index and weight of nutrition management quality of patients with nasopharyngeal carcinoma during peri-radiotherapy. RESULTS: The effective questionnaire recovery rates of the two rounds of letters were 90.005% and 100%, respectively, and the expert authority coefficients were 0.906 and 0.918, respectively. The Kendall harmony coefficients of the two rounds of letters were 0.271 to 0.313 and 0.309 to 0.349, respectively. The nutrition management quality evaluation index of patients with nasopharyngeal carcinoma during peri-radiotherapy was constructed and included 3 first-level indexes, 10 second-level indexes, and 71 third-level indexes. CONCLUSION: The evaluation index of the nutrition management quality of patients with nasopharyngeal carcinoma during peri-radiotherapy is scientific and reliable, and it may have a certain guiding significance for nurses to evaluate the quality of nutrition management of these patients during this period.

Engineering cation vacancies in high-entropy layered double hydroxides for boosting the oxygen evolution reaction.

High-entropy layered double hydroxides (HE-LDHs) are emerging as promising electrocatalysts towards the OER due to their high-entropy effect and the cocktail effect. However, the catalytic activity and stability of HE-LDHs is, as yet, unsatisfactory. Herein, we designed FeCoNiCuZn LDHs with rich cation vacancies, which need only low overpotentials of 227, 275 and 293 mV to reach 10, 100 and 200 mA cm-2, respectively, and show almost no decay up to 200 h at 200 mA cm-2. DFT calculations validate that the cation vacancies can boost the intrinsic activity of HE-LDHs through optimizing the adsorption energy of OER intermediates.

In-situ surface reconstruction of single-crystal (NiFe)3Se4 nano-pyramid arrays for efficient oxygen evolution.

Transition metal-based selenides (TMSe) are considered as efficient pre-electrocatalysts towards oxygen evolution reaction (OER). However, the key factor in determining the surface reconstruction of TMSe under OER condition is not yet clear. Herein, we uncover that the crystallinity of TMSe will obviously impact the conversion degree from TMSe to transition metal oxyhydroxides (TMOOH) during OER. A novel single-crystal (NiFe)3Se4 nano-pyramid array grown on NiFe foam is fabricated by a facile one-step polyol process, which exhibits an excellent OER activity and stability, only requiring 170 mV to reach a current density of 10 mA cm-2 and can sustain for more than 300 h. In situ Raman spectrum studies reveals that the single-crystal (NiFe)3Se4 is partially oxidized on its surface during OER, generating a dense heterostructure of (NiFe)OOH/(NiFe)3Se4. Benefiting from the in situ formed heterointerface, the adsorption of OER intermediates on Ni active sites calculated by density functional theory (DFT) analysis is optimized, leading to the reduced energy barrier, which accounts for the enhanced intrinsic activity. This work not only reports a novel single-crystal (NiFe)3Se4 nano-pyramid array electrocatalyst with high-efficient OER performance, but also gains a deep insight into the role of the crystallinity of TMSe on the surface reconstruction during OER.