Construction of Single-Atom Catalysts for N, O Synergistic Coordination and Application to Electrocatalytic O2 Reduction.

Replacing expensive platinum oxygen reduction reaction (ORR) catalysts with atomically dispersed single-atom catalysts is an effective way to improve the energy conversion efficiency of fuel cells. Herein, a series of single-atom catalysts, TM-N2O2Cx (TM=Sc-Zn) with TM-N2O2 active units, were designed, and their catalytic performance for electrocatalytic O2 reduction was investigated based on density functional theory. The results show that TM-N2O2Cx exhibits excellent catalytic activity and stability in acidic media. The eight catalysts (TM=Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) are all 4e- reaction paths, among which Sc-N2O2Cx, Ti-N2O2Cx, and V-N2O2Cx follow dissociative mechanisms and the rest are consistent with associative mechanisms. In particular, Co-N2O2Cx and Ni-N2O2Cx enable a smooth reduction in O2 at small overpotentials (0.44 V and 0.49 V, respectively). Furthermore, a linear relationship between the adsorption free energies of the ORR oxygen-containing intermediates was evident, leading to the development of a volcano plot for the purpose of screening exceptional catalysts for ORR. This research will offer a novel strategy for the design and fabrication of exceptionally efficient non-precious metal catalysts on an atomic scale.

Downregulation of lncRNA PpL-T31511 and Pp-miRn182 Promotes Hydrogen Cyanamide-Induced Endodormancy Release through the PP2C-H2O2 Pathway in Pear (Pyrus pyrifolia).

Bud endodormancy is an important, complex process subject to both genetic and epigenetic control, the mechanism of which is still unclear. The endogenous hormone abscisic acid (ABA) and its signaling pathway play important roles in the endodormancy process, in which the type 2C protein phosphatases (PP2Cs) is key to the ABA signal pathway. Due to its excellent effect on endodormancy release, hydrogen cyanamide (HC) treatment is considered an effective measure to study the mechanism of endodormancy release. In this study, RNA-Seq analysis was conducted on endodormant floral buds of pear (Pyrus pyrifolia) with HC treatment, and the HC-induced PP2C gene PpPP2C1 was identified. Next, software prediction, expression tests and transient assays revealed that lncRNA PpL-T31511-derived Pp-miRn182 targets PpPP2C1. The expression analysis showed that HC treatment upregulated the expression of PpPP2C1 and downregulated the expression of PpL-T31511 and Pp-miRn182. Moreover, HC treatment inhibited the accumulation of ABA signaling pathway-related genes and hydrogen peroxide (H2O2). Furthermore, overexpression of Pp-miRn182 reduced the inhibitory effect of PpPP2C1 on the H2O2 content. In summary, our study suggests that downregulation of PpL-T31511-derived Pp-miRn182 promotes HC-induced endodormancy release in pear plants through the PP2C-H2O2 pathway.

A novel framework for three-dimensional electrical impedance tomography reconstruction of maize ear via feature reconfiguration and residual networks.

Electrical impedance tomography (EIT) provides an indirect measure of the physiological state and growth of the maize ear by reconstructing the distribution of electrical impedance. However, the two-dimensional (2D) EIT within the electrode plane finds it challenging to comprehensively represent the spatial distribution of conductivity of the intact maize ear, including the husk, kernels, and cob. Therefore, an effective method for 3D conductivity reconstruction is necessary. In practical applications, fluctuations in the contact impedance of the maize ear occur, particularly with the increase in the number of grids and computational workload during the reconstruction of 3D spatial conductivity. These fluctuations may accentuate the ill-conditioning and nonlinearity of the EIT. To address these challenges, we introduce RFNetEIT, a novel computational framework specifically tailored for the absolute imaging of the three-dimensional electrical impedance of maize ear. This strategy transforms the reconstruction of 3D electrical conductivity into a regression process. Initially, a feature map is extracted from measured boundary voltage via a data reconstruction module, thereby enhancing the correlation among different dimensions. Subsequently, a nonlinear mapping model of the 3D spatial distribution of the boundary voltage and conductivity is established, utilizing the residual network. The performance of the proposed framework is assessed through numerical simulation experiments, acrylic model experiments, and maize ear experiments. Our experimental results indicate that our method yields superior reconstruction performance in terms of root-mean-square error (RMSE), correlation coefficient (CC), structural similarity index (SSIM), and inverse problem-solving time (IPST). Furthermore, the reconstruction experiments on maize ears demonstrate that the method can effectively reconstruct the 3D conductivity distribution.

Densely populated tiny RuO2 crystallites supported by hierarchically porous carbon for full acidic water splitting.

The exploitation of highly active bifunctional electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acidic media has been a subject receiving immense interest. However, the existing catalysts usually suffer from low catalytic efficiency and poor corrosion resistance under acidic conditions. Herein, we report a facile molten salt method to fabricate ruthenium dioxide nanoparticles supported by hierarchically porous carbon (RuO2/PC) as a bifunctional electrocatalyst for full water splitting under strong acidic conditions. The formation of a densely populated nanocrystalline RuO2/carbon heterostructure helps expose catalytic sites, accelerates the mass transfer rate, and further enhances the acid resistance of RuO2 nanoparticles. The as-synthesized RuO2/PC consequently exhibits superior catalytic performance for the OER with an overpotential of 181 mV upon 10 mA cm-2 compared to that of the commercial RuO2 (343 mV) and a comparable performance to Pt/C for the HER (47.5 mV upon 10 mA cm-2) in 0.5 M H2SO4. The RuO2/PC shows promising stability with little degradation over ∼24 h. Impressively, the water electrolyzer based on RuO2/PC shows an overpotential of 326 mV at 10 mA cm-2, much lower than that of the electrolyzer based on the combination of Pt/C and RuO2 (400 mV), indicating its great potential towards practical application.

The relationship between COVID-19-related restrictions and fear of missing out, problematic smartphone use, and mental health in college students: The moderated moderation effect of resilience and social support.

As one of the groups most affected by the epidemic, the mental health of college students during the epidemic is a focus of attention in multiple fields. Based on resource conservation theory, this study investigates the impact of COVID-19-related restrictions on college students' problematic smartphone use and mental health from two perspectives, students' individual factors and external environmental factors, and specifically explores the role of fear of missing out (FoMO), resilience and social support in this context. This study used a questionnaire method, and to control for common method bias, a multitemporal data collection strategy was used. The study used online questionnaire distribution, the final sample included 975 Chinese college students (497 males and 478 females), and of these, 10.3% were freshmen, 31.9% were sophomores, 31.6% were juniors, 12.3% were seniors, and 13.9% were postgraduates. The results of this study showed the following: (1) Perceived COVID-19-related strain was positively correlated with perceived FoMO, problematic smartphone use and mental health problems (depression, anxiety, stress) among college students. (2) FoMO partially mediated the relationship between perceived COVID-19-related restrictions and problematic smartphone use, and it fully mediated the relationship between perceived COVID-19-related restrictions and mental health problems. (3) Resilience and social support co-moderated the relationship between FoMO and problematic smartphone use or mental health problems (depression, anxiety, stress).

Genome-Wide Identification of MAPKK and MAPKKK Gene Family Members and Transcriptional Profiling Analysis during Bud Dormancy in Pear (Pyrus x bretschneideri).

The mitogen-activated protein kinase (MAPK) cascade consisting of three types of reversibly major signal transduction module (MAPKKK, MAPKK, and MAPK) is distributed in eukaryotes. MAPK cascades participate in various aspects of plant development, including hormone responses, cell division and plant dormancy. Pear is one of the most economically important species worldwide, and its yield is directly affected by dormancy. In this study, genome-wide identification of MAPKK and MAPKKK gene family members in Pyrus x bretschneideri and transcriptional expression analysis of MAPK cascades during pear dormancy were performed. We identified 8 MAPKKs (PbrMKKs) and 100 MAPKKKs (PbrMAPKKKs) in Pyrus using recent genomic information. PbrMAPKKs were classified into four subgroups based on phylogenetic analysis, whereas PbrMAPKKKs were grouped into 3 subfamilies (MEKK, Raf, and ZIK). Most PbrMAPKKKs and PbrMAPKKs in the same subfamily had similar gene structures and conserved motifs. The genes were found on all 17 chromosomes. The comprehensive transcriptome analysis and quantitative real-time polymerase chain reaction (qRT-PCR) results showed that numerous MAPK cascade genes participated in pear bud dormancy. The interaction network and co-expression analyses indicated the crucial roles of the MAPK member-mediated network in pear bud dormancy. Overall, this study advances our understanding of the intricate transcriptional control of MAPKKK-MAPKK-MAPK genes and provides useful information on the functions of dormancy in perennial fruit trees.

Facile Chemical Vapor Modification Strategy to Construct Surface Cyano-Rich Polymer Carbon Nitrides for Highly Efficient Photocatalytic H2 Evolution.

The surface grafting of electro-negative cyano groups on polymer carbon nitrides (PCNs) is an effective way to tail their electronic structure. Despite the significant progress in the synthesis of cyano group-enriched PCN, developing a simple and efficient method remains challenging. Here, a facile strategy was developed for fabricating surface cyano-rich PCN (PCN-DM) with a porous structure via chemical vapor modification using diaminomaleonitrile. The cyano groups of diaminomaleonitrile substituted the amino groups on PCN surface via a deamination. The hydrogen production rate of the PCN-DM was approximately 17 times higher than that of pristine PCN. This significant increase in photocatalytic performance could be assigned to the fusion of cyano groups in the surface of PCN, forming new gap states that broadened the visible-light harvesting and accelerated charge separation for photoredox reactions. This study unveils a promising approach for incorporating functional units in the design of novel photocatalysts for efficient hydrogen production.

Bipolar fluorinated covalent triazine framework cathode with high lithium storage and long cycling capability.

Organic materials with adjustable structures and wide sources are expected to become potential candidates for commercial cathodes of lithium-ion batteries (LIBs). However, most organic materials have unstable structures, poor conductivity, and are easily soluble in electrolytes, resulting in unsatisfactory lithium storage performance. Covalent-organic frameworks have attracted extensive attention due to their stable frame structures, adjustable pore structures and functionalized official groups. Herein, a fluorinated covalent triazine framework (FCTF) is synthesized by a simple ion-thermal method. Compared with the fluorine-free covalent triazine frameworks (CTFs), the introduction of fluorine improves the lithium storage performance of CTF. When used as a cathode for lithium ion batteries, FCTF can retain a reversible capacity of 125.6 mA h g-1 after 200 cycles at a current density of 100 mA g-1. Besides, it also delivers 106.3 mA h g-1 after 400 cycles at a current density of 200 mA g-1 with 0.03% decrease per cycle (from 40 to 400 cycles).

Genome-wide analysis of long noncoding RNAs affecting floral bud dormancy in pears in response to cold stress.

The versatile role of long noncoding RNAs (lncRNAs) in plant growth and development has been established, but a systematic identification and analysis of lncRNAs in the pear has not been reported. Bud dormancy is a crucial and complicated protective mechanism for plants in winter. The roles of lncRNAs in the dormancy process remain largely unclear. In this study, we induced pear floral buds to enter into different dormant statuses by simulating four different chilling accumulation conditions. Then, a time series of RNA-seq analysis was performed and we identified 7594 lncRNAs in Pyrus pyrifolia (Burm. F.) Nakai that have not been identified. The sequence and expression of the lncRNAs were confirmed by PCR analysis. In total, 6253 lncRNAs were predicted to target protein-coding genes including 692 cis-regulated pairs (596 lncRNAs) and 13,158 trans-regulated pairs (6181 lncRNAs). Gene Ontology analysis revealed that most of lncRNAs' target genes were involved in catalytic activity, metabolic processes and cellular processes. In the trend analysis, 124 long-term cold response lncRNAs and 80 short-term cold response lncRNAs were predicted. Regarding the lncRNA-miRNA regulatory networks, 59 lncRNAs were identified as potential precursors for miRNA members of 20 families, 586 lncRNAs were targets of 261 pear miRNAs and 53 lncRNAs were endogenous target mimics for 26 miRNAs. In addition, three cold response lncRNAs, two miRNAs and their target genes were selected for expression confirmed. The trend of their expression was consistent with the predicted relationships among them and suggested possible roles of lncRNAs in ABA metabolic pathway. Our findings not only suggest the potential roles of lncRNAs in regulating the dormancy of pear floral buds but also provide new insights into the lncRNA-miRNA-mRNA regulatory network in plants.

Efficient electrocatalytic reduction of carbon dioxide by metal-doped ß12-borophene monolayers.

Electrochemical reduction of CO2 to value-added chemicals and fuels shows great promise in contributing to reducing the energy crisis and environment problems. This progress has been slowed by a lack of stable, efficient and selective catalysts. In this paper, density functional theory (DFT) was used to study the catalytic performance of the first transition metal series anchored TM-Bß12 monolayers as catalysts for electrochemical reduction of CO2. The results show that the TM-Bß12 monolayer structure has excellent catalytic stability and electrocatalytic selectivity. The primary reduction product of Sc-Bß12 is CO and the overpotential is 0.45 V. The primary reduction product of the remaining metals (Ti-Zn) is CH4, where Fe-Bß12 has the minimum overpotential of 0.45 V. Therefore, these new catalytic materials are exciting. Furthermore, the underlying reaction mechanisms of CO2 reduction via the TM-Bß12 monolayers have been revealed. This work will shed insights on both experimental and theoretical studies of electroreduction of CO2.

Electrochemical behavior and voltammetric determination of paracetamol on Nafion/TiO2-graphene modified glassy carbon electrode.

The TiO(2)-graphene (TiO(2)-GR) nanocomposite for paracetamol electrochemical sensing is described. The electrochemical behavior of paracetamol at the Nafion/TiO(2)-GR composite film modified glassy carbon electrode (GCE) was investigated by cyclic voltammetry. The results showed that the incorporation of TiO(2) nanoparticles with graphene significantly enhanced the electrochemical reactivity and voltammetric response of paracetamol. In addition, Nafion acts as an effective solubilizing agent and antifouling coating in the fabrication of the modified electrode. This electrochemical sensor exhibits excellent analytical performance for paracetamol detection at physiological pH with detection limit of 2.1×10(-7) M, linear range of 1-100 µM and reproducibility of 3.6% relative standard deviation.

Hydrothermal preparation and electrochemical sensing properties of TiO(2)-graphene nanocomposite.

A facile hydrothermal method has been developed and shown to be effective for the preparation of TiO(2)-graphene nanocomposite. The as-prepared nanocomposite was characterized using FT-IR spectroscopy, powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The TiO(2)-graphene modified glassy carbon electrode (GCE) exhibited remarkable electron transfer kinetics and electrocatalytic activity toward the oxidation of dopamine (DA). Furthermore, the oxidation of common interfering agent such as ascorbic acid (AA) was significantly suppressed at this modified electrode, which resulted in good selectivity and sensitivity for electrochemical sensing of DA. These results demonstrate that the TiO(2)-graphene hybrid material has promising potential applications in electrochemical sensors and biosensors design.