Cascade Performance of Nitroarenes with Alcohols Boosted by a Hollow Flying Saucer-Shaped Ni-Al2O3 Catalyst via a MOF-Templated Strategy Induced by the Kirkendall Effect.

Catalysts with an open hollow structure can enhance the mass transfer capability of the catalyst during the reaction process, thereby further improving the catalytic performance. In this work, uniform and monodisperse flying-squircher-shaped Al-MOFs were synthesized via a solvothermal method. Furthermore, a hollow structure Al2O3-supported metallic Ni catalyst (termed Ni-Al2O3-HFA) was synthesized via the Kirkendall effect for the hydrogenation-alkylation cascade reaction by employing as-synthesized Al-MOFs as a carrier for impregnation of Ni(NO3)2·6H2O through further calcination and reduction. Various characterizations (e.g., XRD, HADDF-STEM, H2-TPR) were conducted to reveal the superior performance of the developed Ni-Al2O3-HFA catalyst compared to Ni/Al2O3-IWI (Al2O3 obtained from calcination of Al-MOFs) in cascade reaction between nitroarenes and alcohols. We hope to use the MOF template method via the Kirkendall effect to prepare hollow structure nanocatalysts, which can provide a guideline for the preparation of other hollow materials.

Mechanistic Insights into a Co(II)-Coordinated "Free" Metal Site of 2D Zinc-Based MOFs for ß-Alkylation of Secondary Alcohols with Primary Alcohols.

Through in-depth study of the properties and reaction mechanisms of catalysts, it is possible to better optimize catalytic systems and improve reaction efficiency and selectivity. This remains one of the challenges in the field of catalysis. Therefore, the research and design of catalysts play crucial roles in understanding and optimizing catalytic reaction mechanisms. A robust 2D zinc-based MOFs (Zn-HA) supported Co(II) ion catalyst (Zn-HA@Co) has been designed and synthesized via a coordination-assisted strategy for ß-alkylation of secondary alcohols with primary alcohols. The characterization demonstrated that the anchoring of Co(II) on Zn-HA via coordination could efficiently enhance the Co(II) ion dispersity and interaction between Co(II) and Zn-HA MOFs. Importantly, the density functional theory results have provided mechanistic insights into the energy of the HOMO and LUMO of the Zn-HA@Co catalyst as well as the energy change of the entire process after interacting with the reactants and the specific energy changes of each orbital. The synthesized Zn-HA@Co MOFs effectively lower the energy barrier of the catalytic reaction process. We expect that our research and design of catalysts will serve as valuable guideline for understanding and optimizing catalytic reaction mechanisms.

Ultrafine FeF3·0.33H2O Nanocrystal-Doped Graphene Aerogel Cathode Materials for Advanced Lithium-Ion Batteries.

FeF3 has been extensively studied as an alternative positive material owing to its superior specific capacity and low cost, but the low conductivity, large volume variation, and slow kinetics seriously hinder its commercialization. Here, we propose the in situ growth of ultrafine FeF3·0.33H2O NPs on a three-dimensional reduced graphene oxide (3D RGO) aerogel with abundant pores by a facile freeze drying process followed by thermal annealing and fluorination. Within the FeF3·0.33H2O/RGO composites, the three-dimensional (3D) RGO aerogel and hierarchical porous structure ensure rapid diffusion of electrons/ions within the cathode, enabling good reversibility of FeF3. Benefiting from these advantages, a superior cycle behavior of 232 mAh g-1 under 0.1C over 100 cycles as well as outstanding rate performance is achieved. These results provide a promising approach for advanced cathode materials for Li-ion batteries.

Recent Advances in Solid-Electrolyte Interphase for Li Metal Anode.

Lithium metal batteries (LMBs) are considered to be a substitute for lithium-ion batteries (LIBs) and the next-generation battery with high energy density. However, the commercialization of LMBs is seriously impeded by the uncontrollable growth of dangerous lithium dendrites during long-term cycling. The generation and growth of lithium dendrites are mainly derived from the unstable solid-electrolyte interphase (SEI) layer on the metallic lithium anode. The SEI layer is a key by-product formed on the surface of the lithium metal anode during the electrochemical reactions and has been the barrier to development in this area. An ideal SEI layer should possess electrical insulating, superior mechanical modulus, high electrochemical stability, and excellent Li-ion conductivity, which could improve the structural stability of the electrode upon a long cycling time. This mini-review carefully summarizes the recent developments in the SEI layer for LMBs, and the relationship between SEI layer optimization and electrochemical property is discussed. In addition, further development direction of a stable SEI layer is proposed.

Rational design of nano-Fe3O4encapsulated in 3D honeycomb biochar for enhanced lithium storage performance.

Developing green materials applied in lithium-ion batteries is of significant importance for the present-day society. Herein, a feasible strategy to construct Fe3O4nanoparticles (NPs) embedded in three-dimensional (3D) honeycomb biochar derived from pleurotus eryngii was proposed. The obtained material consists of Fe3O4NPs (35-85 nm) encapsulated in 3D honeycomb biochar possesses a high specific capacity of 723 mAh g-1at 1.5 A g-1after 1000 cycles. The effectively enhanced cycling life of Fe3O4@C nanocomposites can be ascribed to the small Fe3O4NPs provide lower degree of cracking and high specific capacity, while the honeycomb biochar function like a cage to inhibit huge volume change of Fe3O4NPs during the charge-discharge process.

Elastic, electronic and optical properties of new 2D and 3D boron nitrides.

The current work investigates a novel three-dimensional boron nitride called bulk B4N4 and its corresponding two-dimensional monolayer B4N4 based on the first-principles of density functional theory. The phonon spectra prove that bulk B4N4 and monolayer B4N4 are dynamically stable. The molecular dynamics simulations verify that bulk B4N4 and monolayer B4N4 have excellent thermal stability of withstanding temperature up to 1000 K. The calculated elastic constants state that bulk B4N4 and monolayer B4N4 are mechanically stable, and bulk B4N4 has strong anisotropy. The theoretically obtained electronic structures reveal that bulk B4N4 is an indirect band-gap semiconductor with a band gap of 5.4 eV, while monolayer B4N4 has a direct band gap of 6.1 eV. The valence band maximum is mainly contributed from B-2p and N-2p orbits, and the conduction band minimum mainly derives from B-2p orbits. The electron transitions from occupied N-2p states to empty B-2p states play important roles in the dielectric functions of bulk B4N4 and monolayer B4N4. The newly proposed monolayer B4N4 is a potential candidate for designing optoelectronic devices such as transparent electrodes due to its high transmissivity.

Electronic structures and physical properties of double perovskite A2CoNbO6 (A = Sr, Ba) crystals.

The crystal structures, mechanical properties, lattice dynamics, electronic structures and optical properties of Sr2CoNbO6 and Ba2CoNbO6 have been studied by the first principles of density functional theory. The theoretically obtained crystal parameters of Sr2CoNbO6 and Ba2CoNbO6 are consistent with their experimental ones. Both Sr2CoNbO6 and Ba2CoNbO6 belong to the [Formula: see text] space group at the low-temperature limit and have very weak elastic anisotropy. The former is slightly brittle while the latter is more brittle. Their electronic structures are similar to each other, and Co-3d and O-2p  orbitals constitute the top valence bands while Co-3d orbitals form the bottom conduction bands. Sr2CoNbO6 and Ba2CoNbO6 are indirect band gap semiconductors, and their band gaps are respectively 2.916 and 3.050 eV. The close band gaps are mainly dominated by the similar [Formula: see text] octahedrons in their crystal structures. The electron transitions from O-2p  orbitals in the valence bands to Co-3d orbitals in the conduction bands play important roles in the optical properties of Sr2CoNbO6 and Ba2CoNbO6. Due to the same point group, Sr2CoNbO6 and Ba2CoNbO6 have the same five active lattice vibration modes of [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] and one static lattice vibration mode of [Formula: see text], and the typical displacement patterns are also analyzed in detail.

Comparative analysis of the microRNA transcriptome between yak and cattle provides insight into high-altitude adaptation.

Extensive and in-depth investigations of high-altitude adaptation have been carried out at the level of morphology, anatomy, physiology and genomics, but few investigations focused on the roles of microRNA (miRNA) in high-altitude adaptation. We examined the differences in the miRNA transcriptomes of two representative hypoxia-sensitive tissues (heart and lung) between yak and cattle, two closely related species that live in high and low altitudes, respectively. In this study, we identified a total of 808 mature miRNAs, which corresponded to 715 pre-miRNAs in the two species. The further analysis revealed that both tissues showed relatively high correlation coefficient between yak and cattle, but a greater differentiation was present in lung than heart between the two species. In addition, miRNAs with significantly differentiated patterns of expression in two tissues exhibited co-operation effect in high altitude adaptation based on miRNA family and cluster. Functional analysis revealed that differentially expressed miRNAs were enriched in hypoxia-related pathways, such as the HIF-1α signaling pathway, the insulin signaling pathway, the PI3K-Akt signaling pathway, nucleotide excision repair, cell cycle, apoptosis and fatty acid metabolism, which indicated the important roles of miRNAs in high altitude adaptation. These results suggested the diverse degrees of miRNA transcriptome variation in different tissues between yak and cattle, and suggested extensive roles of miRNAs in high altitude adaptation.

Exosomal microRNAs in giant panda (Ailuropoda melanoleuca) breast milk: potential maternal regulators for the development of newborn cubs.

The physiological role of miRNAs is widely understood to include fine-tuning the post-transcriptional regulation of a wide array of biological processes. Extensive studies have indicated that exosomal miRNAs in the bodily fluids of various organisms can be transferred between living cells for the delivery of gene silencing signals. Here, we illustrated the expression characteristics of exosomal miRNAs in giant panda breast milk during distinct lactation periods and highlighted the enrichment of immune- and development-related endogenous miRNAs in colostral and mature giant panda milk. These miRNAs are stable, even under certain harsh conditions, via the protection of extracellular vesicles. These findings indicate that breast milk may facilitate the dietary intake of maternal miRNAs by infants for the regulation of postnatal development. We also detected exogenous plant miRNAs from the primary food source of the giant panda (bamboo) in the exosomes of giant panda breast milk that were associated with regulatory roles in basic metabolism and neuron development. This result suggested that dietary plant miRNAs are absorbed by host cells and subsequently secreted into bodily fluids as potential cross-kingdom regulators. In conclusion, exosomal miRNAs in giant panda breast milk may be crucial maternal regulators for the development of intrinsic 'slink' newborn cubs.

Differential expression of genes related to glucose metabolism in domesticated pigs and wild boar.

Glucose metabolism is a basic biological process that shows substantial variation within and between species. Using pig as a model organism, we investigated differences in glucose metabolic genes in seven tissues from domesticated pigs (Rongchang pig and Tibetan pig, meanwhile, the Tibetan pig just as a special case of the domesticated pig under plateau condition) and wild boar. We found large differences in the expression of genes involved in multiple aspects of glucose metabolism, including genes associated with glucose transport, gluconeogenesis, and glycolysis. In addition, we identified microRNAs (miRNAs) that may be involved in the divergence of glucose metabolism in pig. A combined analysis of mRNA and miRNA expression indicated that some miRNA:mRNA pairs showed ab facto function in it. Our results provide a valuable resource for further determination of miRNA regulatory roles in pig glucose metabolism and reveal the divergence of glucose metabolism in pigs under domestication.

One-Pot Synthesis of Pomegranate-Structured Fe3 O4 /Carbon Nanospheres-Doped Graphene Aerogel for High-Rate Lithium Ion Batteries.

A unique hierarchically nanostructured composite of iron oxide/carbon (Fe3O4/C) nanospheres-doped three-dimensional (3D) graphene aerogel has been fabricated by a one-pot hydrothermal strategy. In this novel nanostructured composite aerogel, uniform Fe3O4 nanocrystals (5-10 nm) are individually embedded in carbon nanospheres (ca. 50 nm) forming a pomegranate-like structure. The carbon matrix suppresses the aggregation of Fe3O4 nanocrystals, avoids direct exposure of the encapsulated Fe3O4 to the electrolyte, and buffers the volume expansion. Meanwhile, the interconnected 3D graphene aerogel further serves to reinforce the structure of the Fe3O4/C nanospheres and enhances the electrical conductivity of the overall electrode. Therefore, the carbon matrix and the interconnected graphene network entrap the Fe3O4 nanocrystals such that their electrochemical function is retained even after fracture. This novel hierarchical aerogel structure delivers a long-term stability of 634 mA h g(-1) over 1000 cycles at a high current density of 6 A g(-1) (7 C), and an excellent rate capability of 413 mA h g(-1) at 10 A g(-1) (11 C), thus exhibiting great potential as an anode composite structure for durable high-rate lithium-ion batteries.

Synthesis of Hierarchical Nanoporous Microstructures via the Kirkendall Effect in Chemical Reduction Process.

A series of novel hierarchical nanoporous microstructures have been synthesized through one-step chemical reduction of micron size Cu2O and Co3O4 particles. By controlling the reduction time, non-porous Cu2O microcubes sequentially transform to nanoporous Cu/Cu2O/Cu dented cubic composites and hollow eightling-like Cu microparticles. The mechanism involved in the complex structural evolution is explained based on oxygen diffusion and Kirkendall effect. The nanoporous Cu/Cu2O/Cu dented cubic composites exhibit superior electrochemical performance as compared to solid Cu2O microcubes. The reduction of nonporous Co3O4 also exhibits a uniform sequential reduction process from nonporous Co3O4 to porous Co3O4/CoO composites, porous CoO, porous CoO/Co composites, and porous foam-like Co particles. Nanoscale channels originate from the particle surface and eventually develop inside the entire product, resulting in porous foam-like Co microparticles. The Kirkendall effect is believed to facilitate the formation of porous structures in both processes.

Low temperature crystallization of transparent, highly ordered nanoporous SnO2 thin films: application to room-temperature hydrogen sensing.

High surface area highly ordered nanoporous thin films are the current gold standard for gas sensor use, however the nanostructure of such films is prone to collapse at annealing temperatures as low as 250 °C resulting in formation of a dense layer of limited utility. We report on a templating method used to deposit highly ordered nanoporous platinum (Pt)-doped tin dioxide (SnO(2)) thin films that are crystallized by a 100 °C water vapor hydrothermal treatment, with the low temperature process being compatible with a large variety of substrates including plastic. The resulting highly ordered nanoporous, transparent Pt-SnO(2) thin films are mechanically stable and can be annealed, as desired, at temperatures up to 800 °C for removal of the templating materials and tailoring of gas sensitivities without damage to the nanoporous structure. The synthesis method is general, offering a promising strategy for preparing high performance nanoporous metal oxide crystalline films for applications including gas sensing, photocatalysis, and 3(rd) generation photovoltaics. In our example application of the synthesized materials, we find that these Pt-SnO(2) films exhibit exceptional hydrogen gas sensing behavior, rapidly detecting low-level hydrogen concentrations at room temperature; for example, an eight order of magnitude change in electrical resistance is seen in response to 10 000 ppm H(2), with only minimal sensitivity to humidity.