Density Functional Theory Study on the Enhancement Mechanism of the Photocatalytic Properties of the g‑C₃N₄/BiOBr(001) Heterostructure

The van der Waals heterostructures fabricated in two semiconductors are currently attracting considerable attention in various research fields. Our study uses density functional theory calculations within the Heyd–Scuseria–Ernzerhof hybrid functional to analyze the geometric structure and electronic structure of the g-C3N4/BiOBr(001) heterojunction in order to gain a better understanding of its photocatalytic properties. The calculated band alignments show that g-C3N4/BiOBr can function as a type-II heterojunction. In this heterojunction, the electrons and holes can effectively be separated at the interface. Moreover, we find that the electronic structure and band alignment of g-C3N4/BiOBr(001) can be tuned using external electric fields. It is also noteworthy that the optical absorption peak in the visible region is enhanced under the action of the electric field. The electric field may even improve the optical properties of the g-C3N4/BiOBr(001) heterostructure. Given the results of our calculations, it seems that g-C3N4/BiOBr(001) may be significantly superior to visible light photocatalysis

Petrogenesis of Early Cretaceous mafic dikes in southeastern Jiaolai basin, Jiaodong Peninsula, China

<p>Mafic dikes of mainly Early Cretaceous age (130–110 Ma) are widely developed on the Jiaodong Peninsula, China. Previous studies of the dikes, which have focused mainly on occurrences in the Jiaobei uplift and in the Sulu orogenic belt, have thoroughly examined their petrogenesis and geodynamic setting. This study identified four previously unknown mafic dikes (dolerite and lamprophyre) in southeastern Jiaolai basin (near Haiyang city), Jiaodong Peninsula. Detailed geochemical and geochronological analyses were conducted to determine the petrogenesis of the dikes and to infer their geodynamic setting. Zircon U–Pb dating by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) indicates that the dikes were emplaced at ~126 Ma. The dikes are characterized by low SiO₂ contents (44.3–52.3 wt.%), high contents of MgO (7.28–10.13 wt.%), Cr (267–652 ppm), and Ni (93–335 ppm), and high Mg^# values (63–73); they are enriched in large ion lithophile elements (LILEs; Ba, K, and Sr), depleted in high field strength elements (HFSEs; Nb, Ta, P, and Ti), and are characterized by high (⁸⁷Sr/⁸⁶Sr)_i isotope ratios (0.707226–0.708222), low <i>ε</i>_Nd(<i>t</i>) values (−12.3 to −13.6), and zircon <i>ε</i>_Hf(<i>t</i>) values (−15.6 to −23.6). These features suggest that the dikes were derived from enriched subcontinent lithospheric mantle (SCLM). The wide range of Rb/Sr (0.04–0.18) and Ba/Rb (5–34) ratios, and the low and limited range of Dy/Yb (1.93–2.52) and K/Yb (5.71–11.99) ratios of the dikes indicate that the magmas originated from a low degree of partial melting of an amphibole- and phlogopite-bearing lherzolite in the spinel–garnet transition zone. The parental magma might have experienced fractionation of olivine and clinopyroxene during its ascent without significant crustal contamination. Evident depletion of Nb–Ta and Zr–Hf, low and limited range of Th/Yb ratios, elevated Ba/La ratios, constant chondritic Zr/Hf ratios, and a large range of Hf/Sm ratios further indicate that the mantle sources of the dikes were altered by carbonate-related metasomatism from subducted slab-derived fluids, which were most likely related to subduction of the Palaeo-Pacific plate during the Mesozoic. The mafic dikes in the southeastern Jiaolai basin resemble the arc-like mafic dikes in the Jiaobei terrain and the Sulu orogenic belt, and possibly indicate lithospheric thinning induced by slab rollback of the Palaeo-Pacific plate.</p

Sulfide-based MOF material modification of separators: enhancing performance of lithium-sulfur batteries by suppressing shuttle effect

Lithium-sulfur batteries (LSBs) are extensively studied owing to their high theoretical capacity and low cost. However, the shuttle effect of lithium-sulfur batteries hinders their development. In this study, we obtained a modified separator to inhibit the shuttle effect through physical and chemical adsorption. The CoS2 nanosheets (CSNS) derived from a cobalt-based metal-organic framework (Co-MOF) were synthesized by a simple two-step method involving hydrothermal sulfurization and thermal decomposition. The material was then coated onto a Polypropylene (PP) separator using vacuum filtration and assembled into a LSB for systematic testing and research of its electrochemical performance and mechanism. Thanks to the intrinsic polarity of the CSNs and more active sites brought by the Co-MOF material, the modified separator has strong chemical adsorption and catalytic effects on polysulfides, anchoring and accelerating their conversion. When using the CSNs-PP separator, the LSB achieved a high initial capacity of 1002.4 mAh g−1 at 1 C, with only a 0.099% decay per cycle after 500 cycles. The modified separator effectively alleviating the shuttle effect, reducing internal resistance, weakening reaction polarization, and improving the specific capacity, stability, and reversibility of the battery.</p

Controlled Crystallization of Carbon-blended Prussian Blue Analogs for Advanced Sodium-Ion Batteries

Prussian blue analogs (PBAs) are a potential choice for cathodes in sodium-ion batteries. However, their electrochemical performance is hindered by intrinsic structural vacancies and weak electronic conductivity, resulting in a reduced reversible capacity, multiplicative ability, and cycle stability. Herein, the carbon-blended Na2CoFe(CN)6 (COHCF@C) prepared by a controlled crystallization method displays improved electrochemical characteristics. With 70% residual capacity after 200 cycles, the reversible specific capacity of the COHCF@C is 123 mAh g–1 at 1 C. Furthermore, the COHCF@C also exhibits higher structural stability in aqueous electrolytes. Based on experimental results, this enhancement can be attributed to the introduction of carbon, slowing down the crystallization process and resulting in higher crystallinity. Additionally, the reduced water content leads to fewer defects, which improves the utilization of active sites. Overall, the finding provides an experimental basis and theoretical guidance for the application of PBA cells

DNMT 1 maintains hypermethylation of CAG promoter specific region and prevents expression of exogenous gene in fat-1 transgenic sheep

<div><p>Methylation is an important issue in gene expression regulation and also in the fields of genetics and reproduction. In this study, we created fat-1 transgenic sheep, investigated the fine-mapping and the modulatory mechanisms of promoter methylation. Sheep fetal fibroblasts were transfected by pCAG-fat1-IRES-EGFP. Monoclonal cell line was screened as nuclear donor and carried out nuclear transfer (441 transgenic cloned embryos, 52 synchronism recipient sheep). Six offsprings were obtained. Expressions of exogenous genes fat-1 and EGFP were detectable in 10 examined tissues and upregulated omega-3 fatty acid content. Interestingly, more or less EGFP negative cells were detectable in the positive transgenic fetal skin cells. EGFP negative and positive cells were sorted by flow cytometry, and their methylation status in the whole promoter region (1701 nt) were investigated by bisulphate sequencing. The fine-mapping of methylation in CAG promoter were proposed. The results suggested that exogenous gene expression was determined by the methylation status from 721–1346 nt and modulated by methylation levels at 101, 108 and 115 nt sites in CAG promoter. To clarify the regulatory mechanism of methylation, examination of four DNA methyltransferases (DNMTs) demonstrated that hypermethylation of CAG promoter is mainly maintained by DNMT 1 in EGFP negative cells. Furthermore, investigation of the cell surface antigen CD34, CD45 and CD166 indicated that EGFP positive and negative cells belong to different types. The present study systematically clarified methylation status of CAG promoter in transgenic sheep and regulatory mechanism, which will provide research strategies for gene expression regulation in transgenic animals.</p></div

Fine-mapping of DNA methylation in the whole CAG promoter by bisulfite sequencing.

<p><b>(A)</b> DNA methylation status in the whole CAG promoter region in EGFP-positive and negative skin cells from 3 100-day fetuses. The full-length region was scanned by 7 pairs of primers. All the PCR products were ligated into T-vector. At least 12 successful sequencings were obtained for data analysis. DNA methylation rate represents ratio of methylated counts in successful sequencings in corresponding site. DNA methylation (%) shown in the upper and middle figures is the average of three samples. Horizontal axis indicates the 176 CpG sites. The bottom figure shows core promoter regions predicted by online software and alignment with methylation distribution. <b>(B)</b> Methylation levels at CpG site 101, 108, and 115. Each sample carried out 15 successful sequencing. Hollow and solid circles stand for unmethylated and methylated cytosines, respectively. The histogram exhibits the percentage of methylation at the 3 selected CpG sites. <b>(C)</b> Schematic diagram of structural regions and DNA methylation status of CAG promoter. The CAG promoter is made up of four regions: CMV enhancer (1–263 nt), chicken β-actin promoter (264–643 nt), chicken β-actin intron (644–1607 nt) and rabbit globin intron (1607–1701 nt). The CAG promoter methylation patterns include: regulatory region (108–116 nt, 3 CpG dinucleotides), hypermethylation region (516–720 nt, 37 CpG dinucleotides), main methylation different region (721–1346 bp, 85 CpG dinucleotides), common research region (1374–1600 nt, 30 CpG dinucleotides) and irregular complex methylation region (1347–1664 nt, 33 CpG dinucleotides).</p

Primer information for scanning methylation status in CAG promoter region.

<p>Primer information for scanning methylation status in CAG promoter region.</p

Primer sequences and their designated application in this study.

<p>Primer sequences and their designated application in this study.</p

The omega-3 and omega-6 fatty acid content patterns in two tissues.

<p><b>(A)</b> The percentages of omega-3, omega-6 and other fatty acids in liver from DSH1, DSH2, DSH3 and control individuals. <b>(B)</b> The percentages of omega-3, omega-6 and other fatty acids in brain. <b>(C)</b> Omega-3/omega-6 ratio. fat-1 gene increases the ratio of omega-3/omega-6 fatty acids.</p

Cell type was analyzed through cell surface antigen markers CD34, CD45 and CD166 by flow cytometry.

<p>Marker CD34 was barely detectable. Marker CD45 and CD166 occupied 7.9% and 16.7% in EGPF-positive cells, 18.3% and 26.8% in EGFP-negative ones, respectively. The experiment was carried out triplicately. The positive cells of surface antigen share the B1 and B2 areas.</p