Unravelling the atomistic mechanisms underpinning the morphological evolution of Al-alloyed hematite.

Hydrothermal synthesis based upon the use of Al3+ as the dopant and/or ethanol as the solvent is effective in promoting the growth of hematite into nanoplates rich in the (001) surface, which is highly active for a broad range of catalytic applications. However, the underpinning mechanism for the flattening of hematite crystals is still poorly comprehended. To close this knowledge gap, in this work, we have attempted intensive computational modelling to construct a binary phase diagram for Fe2O3-Al2O3 under typical hydrothermal conditions, as well as to quantify the surface energy of hematite crystal upon coverage with Al3+ and ethanol molecules. An innovative coupling of density functional theory calculation, cluster expansion and Monte Carlo simulations in analogy to machine learning and prediction was attempted. Upon successful validation by experimental observation, our simulation results suggest an optimum atomic dispersion of Al3+ within hematite in cases when its concentration is below 4 at% otherwise phase separation occurs, and discrete Al2O3 nano-clusters can be preferentially formed. Computations also revealed that the adsorption of ethanol molecules alone can reduce the specific surface energy of the hematite (001) surface from 1.33 to 0.31 J m-2. The segregation of Al3+ on the (001) surface can further reduce the specific surface energy to 0.18 J m-2. Consequently, the (001) surface growth is inhibited, and it becomes dominant after the disappearance of other surfaces upon their continual growth. This work provides atomistic insights into the synergistic effect between the aluminium textural promoter and the ethanol capping agent in determining the morphology of hematite nanoparticles. The established computation approach also applies to other oxide-based catalysts in controlling their surface growth and morphology, which are critical for their catalytic applications.

Characteristics of conserved microRNAome and their evolutionary adaptation to regulation of immune defense functions in the spleen of silver carp and bighead carp.

Immune defense functions of silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) have shown obvious evolutionary divergence. MiRNAs participate in the fine regulation of immune function. However, the evolutionary adaptation of miRNAs in the regulation of immune defense function is still poorly understood in silver carp and bighead carp. Here, small RNA libraries were constructed from the spleen tissue of one-year-old and three-year-old healthy silver carp and bighead carp, 424 and 422 known conserved miRNAs were respectively identified from the spleen of silver carp and bighead carp by bioinformatic analysis, which 398 were shared between the two species. These conserved miRNAs showed highly similar expression patterns between silver carp and bighead carp, but the abundance in spleen varied greatly in different species. Family analysis showed that miRNA families including mir-8, mir-7, mir-23, mir-338, mir-30, mir-27, mir-221, mir-19, mir-181, mir-17, mir-15, mir-148, mir-130, mir-10 and let-7 were the main miRNAs in the spleen of silver carp and bighead carp. 27 and 51 significant differentially expressed (SDE) miRNAs were identified from silver carp and bighead carp, respectively. Evolution analysis for the predicted target genes of SDE-miRNAs showed that ten biological processes such as blood coagulation, cell adhesion mediated by integrin and adaptive immune response were positively selected. In addition, immune genes including TLR3, NFATC3, MALT1, B2M, GILT and MHCII were positively selected only in silver carp, and they were specifically targeted by the SDE-miRNAs including miR-9-5p, miR-196a-5p, miR-375, miR-122, miR-722, miR-132-3p, miR-727-5p, miR-724, miR-19d-5p and miR-138-5p, respectively. PLA2G4 in Fc epsilon RI signaling pathway was positively selected only in bighead carp and was specifically targeted by the SDE-miRNAs including miR-222b, miR-22b-5p, miR-15c, miR-146a, miR-125c-3p, miR-221-5p, miR-2188-5p, miR-142a-3p, miR-212, miR-138-5p and miR-15b-5p. In particular, SDE-miRNAs such as miR-144-3p, miR-2188-3p, miR-731, miR-363-3p and miR-218b could simultaneously target multiple evolutionarily differentiated immune-related genes. These results indicated that in the spleen of silver carp and bighead carp, conserved miRNAs have obvious evolutionary adaptations in the regulation of immune defense function. The results of this study can provide valuable resources for further revealing themechanism of miRNA in the formation of resistance traits evolution between silver carp and bighead carp.

Weighted gene co-expression network analysis identified hub genes critical to fatty acid composition in Gushi chicken breast muscle.

BACKGROUND: The composition and content of fatty acids in the breast muscle are important factors influencing meat quality. In this study, we investigated the fatty acid composition and content in the breast muscle of Gushi chickens at different developmental stages (14 weeks, 22 weeks, and 30 weeks). Additionally, we utilized transcriptomic data from the same tissue and employed WGCNA and module identification methods to identify key genes associated with the fatty acid composition in Gushi chicken breast muscle and elucidate their regulatory networks. RESULTS: Among them, six modules (blue, brown, green, light yellow, purple, and red modules) showed significant correlations with fatty acid content and metabolic characteristics. Enrichment analysis revealed that these modules were involved in multiple signaling pathways related to fatty acid metabolism, including fatty acid metabolism, PPAR signaling pathway, and fatty acid biosynthesis. Through analysis of key genes, we identified 136 genes significantly associated with fatty acid phenotypic traits. Protein-protein interaction network analysis revealed that nine of these genes were closely related to fatty acid metabolism. Additionally, through correlation analysis of transcriptome data, we identified 51 key ceRNA regulatory networks, including six central genes, 7 miRNAs, and 28 lncRNAs. CONCLUSION: This study successfully identified key genes closely associated with the fatty acid composition in Gushi chicken breast muscle, as well as their post-transcriptional regulatory networks. These findings provide new insights into the molecular regulatory mechanisms underlying the flavor characteristics of chicken meat and the composition of fatty acids in the breast muscle.

Transcriptome analysis reveals FABP5 as a key player in the development of chicken abdominal fat, regulated by miR-122-5p targeting.

BACKGROUND: The development of abdominal fat and meat quality are closely related and can impact economic efficiency. In this study, we conducted transcriptome sequencing of the abdominal fat tissue of Gushi chickens at 6, 14, 22, and 30 weeks, and selected key miRNA-mRNA regulatory networks related to abdominal fat development through correlation analysis. RESULTS: A total of 1893 differentially expressed genes were identified. Time series analysis indicated that at around 6 weeks, the development of chicken abdominal fat was extensively regulated by the TGF-ß signaling pathway, Wnt signaling pathway, and PPAR signaling pathway. However, at 30 weeks of age, the apoptosis signaling pathway was the most significant, and correlation analysis revealed several genes highly correlated with abdominal fat development, including Fatty Acid Binding Protein 5 (FABP5). Based on miRNA transcriptome data, it was discovered that miR-122-5p is a potential target miRNA for FABP5. Cell experiments showed that miR-122-5p can directly target FABP5 to promote the differentiation of preadipocytes. CONCLUSION: The present study confirms that the key gene FABP5 and its target gene miR-122-5p are critical regulatory factors in the development of chicken abdominal fat. These results provide new insights into the molecular regulatory mechanisms associated with the development of abdomen-al fat in chickens.

High production of furfural by flash pyrolysis of C6 sugars and lignocellulose by Pd-PdO/ZnSO4 catalyst.

Furfural (C5H4O2) is an important platform chemical for the synthesis of next-generation bio-fuels. Herein, we report a novel and reusable heterogeneous catalyst, Pd-PdO/ZnSO4 with 1.1 mol% palladium (Pd), for the production of furfural by flash pyrolysis of lignocelluloses at 400 °C. For both dry and wet C6 cellulose and its monomers, the furfural yields reach 74-82 mol%, relative to 96 mol% from C5 xylan and 23-33 wt% from sugarcane bagasse and corncob. The catalyst has a well-defined structure and bifunctional property, comprising a ZnSO4 support for the dehydration and isomerization of glucose, and a local core-shell configuration for metallic Pd0 encapsulated by an oxide (PdO) layer. The PdO layer is active for the Grob fragmentation of formaldehyde (HCHO) from glucose, which is subsequently in-situ steam reformed into syn-gas (i.e. H2 and CO), whereas the Pd0 core is active in promoting the last dehydration step for the formation of furfural.

Cu(II) removal from water by trimercapto-s-triazine trisodium salt modified alkaline lignin.

To overcome the poor removal ability of alkaline lignin (AL) toward heavy metals, trimercapto-s-triazine trisodium salt (TMT) was selected as the modifying agent to introduce reaction groups. The Fourier transform infrared (FT-IR) spectra and the scanning electron microscopy (SEM) suggested that -SNa, C-N, and C = N groups were successfully introduced. Copper (II) was applied to evaluate the uptake performance of the adsorbent (AL-TMT). Adsorbent dosage and solution pH were taken into account to study their effects in the batch experiments. The pseudo-second-order dynamics and Langmuir models better described the experimental data. Nitrogen (N) and carbon (C) functional groups in thiotriazinone carried by AL-TMT were determined to be the primary uptake sites through X-ray photoelectron spectroscopy (XPS), FT-IR, and electrostatic potential (ESP). The selective experiments of AL-TMT toward Cd(II), Cu(II), Pb(II), Zn(II), Co(II), and Mg(II) were performed. It showed that AL-TMT possessed better adsorption selectivity toward Cu(II) than others. Furthermore, the density functional theory (DFT) calculations of thiotriazinone in AL-TMT also exhibited the lowest binding energy toward Cu than toward others. This work may provide a theoretical basis to facilitate the extraction of specific heavy metals from water or wastewater by using such modified alkaline lignin.

A polymeric hydrogel electrocatalyst for direct water oxidation.

Metal-free electrocatalysts represent a main branch of active materials for oxygen evolution reaction (OER), but they excessively rely on functionalized conjugated carbon materials, which substantially restricts the screening of potential efficient carbonaceous electrocatalysts. Herein, we demonstrate that a mesostructured polyacrylate hydrogel can afford an unexpected and exceptional OER activity - on par with that of benchmark IrO2 catalyst in alkaline electrolyte, together with a high durability and good adaptability in various pH environments. Combined theoretical and electrokinetic studies reveal that the positively charged carbon atoms within the carboxylate units are intrinsically active toward OER, and spectroscopic operando characterizations also identify the fingerprint superoxide intermediate generated on the polymeric hydrogel backbone. This work expands the scope of metal-free materials for OER by providing a new class of polymeric hydrogel electrocatalysts with huge extension potentials.

Lithium stabilizes square-two-dimensional metal sheets: a computational exploration.

Based on the M4-square-containing M4Li2 (M = Al, Ga, In, Tl, Ge, Sn, Pb, Sb, Bi, Cu, Ag, Au, and Hg) clusters, we computationally designed two-dimensional (2D) M2Li sheets consisting of M4-square motifs. The four M2Li-I (M = Sb, Bi, Ag, and Au) monolayers with Li square sublayer sandwiched between two M square sublayers (P4/mmm space group) were confirmed to be stable (high cohesive energies, positive vibrational frequencies, moderate Young's moduli, and structural integrity during first-principles molecular dynamics simulations at 500 K), and the particle swarm optimization (PSO) method identified these constructed monolayers as the global minima in the 2D space. The three M2Li-I (M = Sb, Bi, and Ag) monolayers demonstrated a half-auxetic behavior. Ag2Li-I could well activate CO2 and convert it into HCOOH by following the path * → *CO2 → *OCHO → *HCOOH → *+HCOOH. Particularly, Ag2Li-I shows great promise as an electrocatalyst for CO2 reduction as its limiting potential is as low as 0.40 (0.27) V without (with) considering the solvent effect. Our theoretical explorations reveal that lithium can stabilize the square metal monolayers, and the stable square binary metal sheets exhibit diverse mechanical and electrochemical properties, which can be used in the fields of mechanics and electrochemical catalysis.

Silica-assisted pyro-hydrolysis of CaCl2 waste for the recovery of hydrochloric acid (HCl): Reaction pathways with the evolution of Ca(OH)Cl intermediate by experimental investigation and DFT modelling.

The chlorine evolution mechanism remains unclear during the thermal treatment of CaCl2/Ca(OH)Cl-containing solid waste. In this paper, we have conducted both experimental investigation and density functional theory (DFT) calculation to elucidate the mechanism of pyro-hydrolysis of CaCl2 with and without SiO2 in the temperature ranges of 400-900 °C. It was determined that pyro-hydrolysis of CaCl2 alone generated a maximum of 12% HCl by decomposition into Ca(OH)Cl, which is a stable intermediate that can be reverted to CaCl2 at 800 °C. Upon the addition of SiO2 at an equimolar ratio to CaCl2, the HCl release extent was accelerated to 50% at 900 °C. Both experiments and DFT calculations prove that the added SiO2 can promote the dissociation of water molecules which provides hydroxyl ions that enable the conversion of CaCl2 into Ca(OH)Cl at low temperatures. The resulting Ca(OH)Cl can also quickly react with SiO2 to form Cl-bearing silicates such as Ca2SiO3Cl2 and Ca3SiO4Cl2 with weakened CaCl bond that are relatively easy to cleave into Cl-free CaSiO3 and HCl(g) from 800 °C.

MX Anti-MXenes from Non-van der Waals Bulks for Electrochemical Applications: The Merit of Metallicity and Active Basal Plane.

Two-dimensional transition-metal compounds (2DTMCs) are promising materials for electrochemical applications, but 2DTMCs with metallicity and active basal planes are rare. In this work, we proposed a simple and effective strategy to extract 2DTMCs from non-van der Waals bulk materials and established a material library of 79 2DTMCs, which we named as anti-MXenes since they are composed of one M atomic layer sandwiched by two X atomic layers. By means of density functional theory computations, 24 anti-MXenes were confirmed to be thermodynamically, dynamically, mechanically, and thermally stable. The metallicity and active basal plane endow these anti-MXenes with potential as excellent electrode materials, for example, as electrocatalysts for hydrogen evolution reactions (HER). Among the noble-metal free anti-MXenes with favorable H-binding, CuS can boost HER at the whole range of H coverages, while CoSi, FeB, CoB, and CoP show promise for HER at some specific H coverages. The active sites are the tetra-coordinating nonmetal atoms at the basal planes, thus rendering a very high density of active sites for these materials. CoB is also a promising anode material for lithium-ion batteries, showing low Li diffusion energy barriers, a very high capacity, and a suitable open circuit voltage. This work promotes the "computational exfoliation" of 2D materials from non-van der Waals bulks and exemplifies the applications of anti-MXenes in various electrochemical processes.

A super stable assembled P nanowire with variant structural and magnetic/electronic properties via transition metal adsorption.

By means of first-principles calculations, we systematically investigated the structure, stability and magnetic and electronic properties of one-dimensional P nanowire (1D-P10 NW) assembled by Pn subunits (n = 2, 8) and transition metal doped 1D-P10 NW. Our calculations showed that the assembled 1D-P10 NW is super stable in thermodynamic, dynamic, thermal and chemical perspectives. Moreover, when the assembled 1D-P10 NW is decorated with transition metals (TM = Ti ∼ Zn, Zr ∼ Mo), structural transformation occurs (to sandwich or quasi-sandwich chains), and various magnetic and electronic characteristics are introduced to the nanowire. Particularly, the sandwich chains 1D-Mn2@P10 and 1D-V1@P5 are a ferromagnetic semiconductor and a ferromagnetic half-metal, respectively, and the magnetic anisotropy energies are both ∼0.3 meV per Mn/V atom. Our theoretical studies proposed a super stable 1D P nanowire and also offer a feasible approach to reach P5-TM-P5-TM chains with diverse magnetic and electronic properties, as well as ferromagnetic vdW-type 2D systems, which are promising in nanoelectronic devices and spintronics.

Metallic FeSe monolayer as an anode material for Li and non-Li ion batteries: a DFT study.

By means of density functional theory computations, we explored the electrochemical performance of an FeSe monolayer as an anode material for lithium and non-lithium ion batteries (LIBs and NLIBs). The electronic structure, adsorption, diffusion, and storage behavior of different metal atoms (M) in FeSe were systematically investigated. Our computations revealed that M adsorbed FeSe (M = Li, Na and K) systems show metallic characteristics that give rise to good electrical conductivity and mobility with low activation energies for diffusion (0.16, 0.13 and 0.11 eV for Li, Na, and K, respectively) of electrons and metal atoms in the materials, indicative of a fast charge/discharge rate. In addition, the theoretical capacities of the FeSe monolayer for Li, Na and K can reach up to 658, 473, and 315 mA h g-1, respectively, higher than that of commercial graphite (372 mA h g-1 for Li, 284 mA h g-1 for Na, and 273 mA h g-1 for K), and the average open-circuit voltage is moderate (0.38-0.88 V for Li, Na and K). All these characteristics suggest that the FeSe monolayer is a potential anode material for alkali-metal rechargeable batteries.

Polymorphism of low dimensional boron nanomaterials driven by electrostatic gating: a computational discovery.

The successful synthesis of two-dimensional (2D) boron sheets typically relies on the utilization of a silver surface, which acts as a gated substrate compensating for the electron-deficiency of boron. However, how the structures of one-dimensional (1D) boron are affected by the gating effect remains unclear. By means of an unbiased global minimum structure search and density functional theory (DFT) computations, we discovered the coexistence of 2D boron sheets and 1D ribbons triggered by electrostatic gating. Specifically, at a low excess charge density level (<0.1 e per atom), 2D boron sheets dominate the low energy configurations. As the charge density increases (>0.3 e per atom), more 1D boron ribbons emerge, while the number of 2D layers is reduced. Additionally, a number of low-lying 1D boron ribbons were discovered, among which a flat borophene-like ribbon (FBR) was predicted to be stable and possess high mechanical strength. Moreover, the electride Ca2N was identified as an ideal substrate for the fabrication of the FBR because of its ability to supply a strong electrostatic field. This work bridges the gap between 2D and 1D boron structures, reveals the polymorphism of 1D boron ribbons under the electrostatic gating effect, and in general provides broad implications for future synthesis and applications of low-dimensional boron materials.

Tackling the Activity and Selectivity Challenges of Electrocatalysts toward the Nitrogen Reduction Reaction via Atomically Dispersed Biatom Catalysts.

Developing efficient catalysts for nitrogen fixation is becoming increasingly important but is still challenging due to the lack of robust design criteria for tackling the activity and selectivity problems, especially for electrochemical nitrogen reduction reaction (NRR). Herein, by means of large-scale density functional theory (DFT) computations, we reported a descriptor-based design principle to explore the large composition space of two-dimensional (2D) biatom catalysts (BACs), namely, metal dimers supported on 2D expanded phthalocyanine (M2-Pc or MM'-Pc), toward the NRR at the acid conditions. We sampled both homonuclear (M2-Pc) and heteronuclear (MM'-Pc) BACs and constructed the activity map of BACs by using N2H* adsorption energy as the activity descriptor, which reduces the number of promising catalyst candidates from over 900 to less than 100. This strategy allowed us to readily identify 3 homonuclear and 28 heteronuclear BACs, which could break the metal-based activity benchmark toward the efficient NRR. Particularly, using the free energy difference of H* and N2H* as a selectivity descriptor, we screened out five systems, including Ti2-Pc, V2-Pc, TiV-Pc, VCr-Pc, and VTa-Pc, which exhibit a strong capability of suppressing the competitive hydrogen evolution reaction (HER) with favorable limiting potential of -0.75, -0.39, -0.74, -0.85, and -0.47 V, respectively. This work not only broadens the possibility of discovering more efficient BACs toward N2 fixation but also provides a feasible strategy for rational design of NRR electrocatalysts and helps pave the way to fast screening and design of efficient BACs for the NRR and other electrochemical reactions.

Semiconducting SN2 monolayer with three-dimensional auxetic properties: a global minimum with tetracoordinated sulfurs.

Designing new two-dimensional (2D) materials, exploring their unique properties and diverse potential applications are of paramount importance to condensed matter physics and materials science. In this work, we predicted a novel 2D SN2 monolayer (S-SN2) by means of density functional theory (DFT) computations. In the S-SN2 monolayer, each S atom is tetracoordinated with four N atoms, and each N atom bridges two S atoms, thus forming a tri-sublayer structure with square lattice. The monolayer exhibits good stability, as demonstrated by the moderate cohesive energy, all positive phonon modes, and the structural integrity maintained through 10 ps molecular dynamics simulations up to 1000 K. It is an indirect-bandgap semiconductor with high hole mobility, and the bandgap can be tuned by changing the thickness and external strains (the indirect-bandgap to direct-bandgap transition occurs when the biaxial tensile strain reaches 4%). Significantly, it has large Young's modulus and three-dimensional auxetic properties (both in-plane and out-of-plane negative Poisson's ratios). Therefore, the S-SN2 monolayer holds great potential applications in electronics, photoelectronics and mechanics.

Spindle nodal chain in three-dimensional α' boron.

Topological metals/semimetals (TMs) have emerged as a new frontier in the field of quantum materials. A few two-dimensional (2D) boron sheets have been suggested as Dirac materials, however, to date TMs made of three-dimensional (3D) boron structures have not been found. Herein, by means of systematic first principles computations, we discovered that a rather stable 3D boron allotrope, namely 3D-α' boron, is a nodal-chain semimetal. In momentum space, six nodal lines and rings contact each other and form a novel spindle nodal chain. This 3D-α' boron can be formed by stacking 2D wiggle α' boron sheets, which are also nodal-ring semimetals. In addition, our chemical bond analysis revealed that the topological properties of the 3D and 2D boron structures are related to the π bonds between boron atoms, however, the bonding characteristics are different from those in the 2D and 3D carbon structures.

Electrochemiluminescence signal amplification combined with a conformation-switched hairpin DNA probe for determining the methylation level and position in the Hsp53 tumor suppressor gene.

We report a new strategy for detection of the methylation level and position in the Hsp53 tumor suppressor gene based on the electrochemiluminescence signal amplification combined with a conformation-switched hairpin DNA probe for improving selectivity.